JP2011248042A - Liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device having superior viewing angle and brightness, in which display unevenness due to environmental change, and variations in the viewing angle between lots generated in bonding in a "roll to panel" manufacturing method are reduced, and to provide a method of manufacturing the liquid crystal display device.SOLUTION: The liquid crystal display device includes a first optical compensation layer, a vertical aligned liquid crystal cell, and a second optical compensation layer which are installed therein in this order. The first optical compensation layer is a positive A plate layer, the second optical compensation layer is a negative C plate layer, and prescribed formulas are satisfied by the wavelength dispersion DSP (LC) of liquid crystal, the wavelength dispersion DSP (CELL) of a crystal cell, the wavelength dispersion DSP (I) of the first optical compensation layer and the wavelength dispersion DSP (II) of the second optical compensation layer.

Description

  The present invention relates to a liquid crystal display device and a manufacturing method thereof. More specifically, the present invention relates to a liquid crystal display device that is excellent in viewing angle and brightness, has reduced display unevenness due to environmental changes, and variation in viewing angle between lots that occurs during bonding in a “roll to panel” manufacturing method, and a manufacturing method thereof.

  The liquid crystal display device is advantageous in that it is thinner and lighter than a CRT (Cathode Ray Tube), can be driven at a low voltage, and consumes less power. Therefore, liquid crystal display devices are used in various electronic devices such as televisions, notebook PCs (personal computers), desktop PCs, PDAs (mobile terminals), and mobile phones.

  In recent years, VA (Vertical Alignment) type liquid crystal display devices using vertical alignment type liquid crystals (liquid crystals having negative dielectric anisotropy) have better viewing angle characteristics than conventional TN type liquid crystal display devices. , Became widely used.

  In general, a liquid crystal cell of a liquid crystal display device includes two liquid crystal cell substrates, a spacer interposed between the two liquid crystal cell substrates, and a liquid crystal material injected into a gap between the two liquid crystal cell substrates. The thickness (cell gap) of the liquid crystal layer into which the liquid crystal material is injected is kept constant by the spacer.

  The liquid crystal layer into which such a liquid crystal material is injected has birefringence per se and produces a phase difference. In order to improve the viewing angle characteristics due to the phase difference, the liquid crystal cell is provided with an optical compensation layer (plate) that cancels the phase difference of the liquid crystal layer.

  Conventionally, as an optical compensation layer (plate) of a VA liquid crystal display device, when the refractive indexes in the X direction, the Y direction, and the Z direction are nx, ny, and nz, respectively, a positive that satisfies the relationship of nx> ny = nz A plate (also referred to as “positive A plate” or “positive A plate”) and a negative C plate satisfying the relationship of nx = ny> nz (also referred to as “negative C plate” or “negative C plate”). ) Has been disclosed on both sides of the cell to realize a wide viewing angle (see, for example, Patent Documents 1 and 2).

  However, the above technique does not consider the white color change from the oblique direction peculiar to the vertical alignment type liquid crystal, and a technique for adjusting the wavelength dispersion of the cell is proposed for the improvement (Patent Document 3). reference). In the above technique, the chromatic dispersion of the cell thickness direction phase difference is set to be reverse chromatic dispersion. However, when such a liquid crystal cell is used to display a high-speed moving image necessary for a television or the like, there is a difference in driving speed of the liquid crystal between RGB and there is a problem such as color shift.

  Therefore, in an actual liquid crystal panel, a cell is used in which chromatic dispersion is substantially flat (the phase difference of the cell does not change with respect to the wavelength). When such a panel is used, the panel having the structure disclosed in Patent Documents 1 and 2 has problems such as insufficient viewing angle and generation of display unevenness due to environmental changes.

  On the other hand, in recent years, in the manufacturing process of liquid crystal panels, a “roll-to-panel manufacturing method” in which a roll-shaped polarizing plate is directly bonded to a liquid crystal panel has begun to be adopted. Since extra stress is generated by feeding from the roll, and minute orientation variations are likely to occur during bonding, variation between lots is a problem.

Japanese Patent No. 3648240 JP 2008-242258 A JP 2008-170514 A

  The present invention has been made in view of the above-mentioned problems and situations, and the problem to be solved is that the viewing angle and brightness are excellent, and display unevenness due to environmental fluctuations and a viewing angle that occurs at the time of pasting in a “roll to panel” manufacturing method. It is an object to provide a liquid crystal display device with reduced lot-to-lot variation and a manufacturing method thereof.

  The above-mentioned problem according to the present invention is solved by the following means.

1. A liquid crystal display device in which a first optical compensation layer, a vertical alignment type liquid crystal cell, and a second optical compensation layer are disposed in this order, wherein the first optical compensation layer is a positive A plate layer, and the second optical compensation layer The compensation layer is a negative C plate layer, and the wavelength dispersion DSP (LC) of the liquid crystal, the wavelength dispersion DSP (CELL) of the liquid crystal cell, the wavelength dispersion DSP (I) of the first optical compensation layer, and the second optical compensation layer. A chromatic dispersion DSP (II) satisfying the following formulas (1) to (5):
Formula (1): 0.01 ≦ DSP (LC) −DSP (CELL) ≦ 0.10
Formula (2): DSP (CELL)> 1.0
Formula (3): 0.6 ≦ DSP (I) ≦ 0.8
Formula (4): DSP (II) ≦ −3.7x [DSP (LC) −DSP (CELL)] + 1.41 Formula (5): DSP (II) ≧ −1.1x [DSP (LC) −DSP ( CELL)] + 1.15 where
DSP (CELL) is the ratio of the value at a wavelength of 450 nm to the value at a wavelength of 650 nm of the thickness direction retardation of the liquid crystal cell,
DSP (LC) is a ratio of a value at a wavelength of 450 nm to a value at a wavelength of 650 nm of Δn · d where Δn is the difference between the ordinary light refractive index and the extraordinary light refractive index when the liquid crystal is vertically aligned and the thickness is d. And
DSP (I) is a ratio of a value at a wavelength of 450 nm to a value at a wavelength of 650 nm of the in-plane retardation of the first optical compensation layer,
DSP (II) is a ratio of a value at a wavelength of 450 nm to a value at a wavelength of 650 nm of the thickness direction retardation of the second optical compensation layer.

2. A first optical compensation layer disposed on the viewing side of the liquid crystal cell, a second optical compensation layer disposed on the backlight side, and an in-plane retardation Ro ₅₅₀ (I) at a wavelength of 550 nm of the first optical compensation layer; 2. The liquid crystal display device according to item 1, wherein the thickness direction retardation Rt ₅₅₀ (II) at a wavelength of 550 nm of the second optical compensation layer satisfies the following formulas (R1) and (R2).
Formula (R1): 100 nm ≦ Ro ₅₅₀ (I) ≦ 200 nm
Formula (R2): 150 nm ≦ Rt ₅₅₀ (II) ≦ 250 nm
3. 3. The liquid crystal display device according to item 1 or 2, wherein an alignment variation coefficient X of the second optical compensation layer satisfies the following formula (X).
Formula (X): 0.00000001 ≦ X ≦ 0.000001
4). The first optical compensation layer contains a polycarbonate-based resin, and the second optical compensation layer contains a cellulose-based resin. The method according to any one of the first to third items, wherein the first optical compensation layer contains a cellulose-based resin. Liquid crystal display device.

  5. A manufacturing method of a liquid crystal display device for manufacturing the liquid crystal display device according to any one of items 1 to 4, wherein a long roll-shaped polarizing plate having the first optical compensation layer is prepared. A method for manufacturing a liquid crystal display device, wherein the liquid crystal cell is bonded by a roll-to-panel manufacturing method.

  By the above means of the present invention, a liquid crystal display device having excellent viewing angle and brightness, reduced display unevenness due to environmental fluctuations and reduced lot-to-lot variation in viewing angle occurring at the time of bonding in a “roll to panel” manufacturing method, and a manufacturing method thereof Can be provided.

Conceptual diagram showing an example of a configuration of a vertical alignment type (VA type) liquid crystal display device Graph showing the range of the examples Conceptual diagram showing the roll-to-panel manufacturing method

  The liquid crystal display device of the present invention is a liquid crystal display device in which a first optical compensation layer, a vertical alignment type liquid crystal cell, and a second optical compensation layer are arranged in this order, and the first optical compensation layer is a positive A plate. The second optical compensation layer is a negative C plate layer, and the wavelength dispersion DSP (LC) of the liquid crystal, the wavelength dispersion DSP (CELL) of the cell, and the wavelength dispersion DSP (I) of the first optical compensation layer. And the wavelength dispersion DSP (II) of the second optical compensation layer satisfies the formulas (1) to (5). This feature is a technical feature common to the inventions according to claims 1 to 5.

As an embodiment of the present invention, from the viewpoint of manifesting the effect of the present invention, a first optical compensation layer is disposed on the viewing side of the cell, a second optical compensation layer is disposed on the backlight side, and the first optical compensation is performed. The in-plane retardation Ro ₅₅₀ (I) at the wavelength 550 nm of the layer and the thickness direction retardation Rt ₅₅₀ (II) at the wavelength 550 nm of the second optical compensation layer satisfy the above formulas (R1) and (R2). preferable. Moreover, it is preferable that the orientation variation coefficient X of the second optical compensation layer is within a range satisfying the formula (X). Furthermore, it is preferable that the first optical compensation layer contains a polycarbonate-based resin and the second optical compensation layer contains a cellulose-based resin.

  As a manufacturing method of the liquid crystal display device of this invention, it is a manufacturing method of the aspect which prepares the elongate roll-shaped polarizing plate which has a said 1st optical compensation layer, and is bonded with the roll to panel manufacturing method with respect to the said liquid crystal cell. It is preferable.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail.

(Outline of configuration of liquid crystal display device)
A typical example of the configuration of the liquid crystal display device of the present invention will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram illustrating an example of a configuration of a vertical alignment type (VA type) liquid crystal display device. In the liquid crystal display device shown in FIG. 1, a first optical compensation layer, a liquid crystal cell, and a second optical compensation layer are disposed in this order between a pair of polarizers whose absorption axes are orthogonal to each other. The absorption axis of the polarizer adjacent to the slow axis of the first retardation layer is orthogonal. The position of the backlight (BL) may be on either the first optical compensation layer side or the second optical compensation layer side. However, as shown in FIG. 1A, the backlight (BL) may be disposed on the second optical compensation layer side. More preferably, it is arranged on the first optical compensation layer side as shown in b).

  The liquid crystal display device shown in FIG. 1 (a) will be described in more detail. The liquid crystal display device includes an upper polarizer 1 (viewing side) and a lower polarizer 5 (backlight) arranged with the liquid crystal cell 3 interposed therebetween. The first optical compensation layer 2 according to the present invention is positioned between the upper polarizer and the liquid crystal cell, and the second optical compensation layer 4 is positioned between the lower polarizer 5 and the liquid crystal cell.

  Hereinafter, each component of the liquid crystal display device will be described in detail.

(Vertical alignment type liquid crystal cell)
The liquid crystal display device of the present invention has a vertical alignment type liquid crystal cell, but the liquid crystal cell according to the present invention needs to satisfy the following formulas (1) and (2).
Formula (1): 0.01 ≦ DSP (LC) −DSP (CELL) ≦ 0.10
Formula (2): DSP (CELL)> 1.0
Here, DSP (CELL) is the ratio (Rt ₄₅₀ / Rt ₆₅₀ ) of the value Rt _{450 at} the wavelength 450 nm to the value Rt _{650 at} the wavelength 650 nm of the retardation in the thickness direction of the cell (Rt ₄₅₀ / Rt ₆₅₀ ), and DSP (LC) is DSP (LC ) Is a ratio of a value at a wavelength of 450 nm to a value at a wavelength of 650 nm of Δn · d where Δn is the difference between the ordinary light refractive index and the extraordinary light refractive index when the liquid crystal is vertically aligned, and the thickness is d.

  In order to form a liquid crystal cell that satisfies the above formula, the thickness of the color filter formed on the glass substrate is changed for each of R (red), G (green), and B (blue). Is increased in the order of R <G <B.), The thickness of the substantial liquid crystal layer changes for each of R, G, and B, and a liquid crystal cell satisfying the above formula can be manufactured (for example, Japanese Patent Laid-Open No. 2008-2008). -134587).

  It can also be achieved by giving the color filter itself a thickness direction phase difference different in R, G, and B (see, for example, Japanese Patent Laid-Open No. 2009-180783). The color filter can be formed on the glass substrate on the viewing side, but can also be formed on the pixel electrode formed on the glass substrate on the backlight side.

  A liquid crystal cell is formed by sealing nematic liquid crystal having negative dielectric anisotropy between such glass substrates. As the nematic liquid crystal having negative dielectric anisotropy, conventionally known ones described in JP-A-2004-204133, JP-A-2004-250668, JP-A-2005-047980, etc. should be used. Can do.

  The wavelength dispersion DSP (LC) of the liquid crystal can be measured using a multi-wavelength Abbe refractometer DR-M2 manufactured by Atago Co., Ltd.

  The wavelength dispersion DSP (CELL) of the liquid crystal cell can be obtained in an environment of 23 ° C. and 55% RH using an Axo scan manufactured by AXOMETRICS.

  In the present invention, a nematic liquid crystal material having a negative dielectric anisotropy between Δn = 0.0815 and Δε = −4.5 can be used for the liquid crystal cell in the present invention.

  The thickness d of the liquid crystal layer is not particularly limited, but can be set to about 3.5 μm when the liquid crystal having the characteristics in the above range is used.

  Since the brightness at the time of white display changes depending on the magnitude of the product Δn · d of the thickness d and the refractive index anisotropy Δn, Δn · d is 0.2 to 0.0 in order to obtain the maximum brightness. It is preferable to set it in the range of 5 μm.

  Note that in a vertical alignment type (VA type) liquid crystal display device, the addition of a chiral material generally used in a TN mode liquid crystal display device is rarely used to degrade dynamic response characteristics, but alignment failure It may be added to reduce the amount.

  In addition, the multi-domain structure is advantageous for adjusting the alignment of the liquid crystal molecules in the boundary region between the domains.

  Note that the “multi-domain structure” refers to a structure in which one pixel of a liquid crystal display device is divided into a plurality of regions. For example, in a vertical alignment type (VA type) liquid crystal display device, the liquid crystal molecules are tilted during white display, so the birefringence of the liquid crystal molecules when viewed from an oblique direction differs between the tilt direction and the opposite direction. Although a difference occurs in luminance and color tone, a multi-domain structure is preferable because viewing angle characteristics of luminance and color tone are improved.

  Specifically, each pixel is composed of two or more regions having different initial alignment states of liquid crystal molecules and averaged, whereby luminance and color tone bias depending on the viewing angle can be reduced. Further, the same effect can be obtained even if each pixel is constituted by two or more different regions where the alignment direction of liquid crystal molecules continuously changes in a voltage application state.

  To form multiple regions with different alignment directions of liquid crystal molecules within one pixel, for example, use methods such as providing slits on electrodes, providing protrusions, changing the electric field direction, or biasing the electric field density. can do.

  In order to obtain a uniform viewing angle in all directions, the number of divisions may be increased. However, a substantially uniform viewing angle can be obtained by using four or more divisions. In particular, it is preferable that the polarizing plate absorption axis can be set at an arbitrary angle when dividing into eight.

  At the region boundary of each domain, the liquid crystal molecules tend to be difficult to respond. In the normally black mode such as the vertical alignment type (VA mode), since black display is maintained, a reduction in luminance becomes a problem. Therefore, it is possible to reduce the boundary region between domains by adding a chiral agent to the liquid crystal material.

  On the other hand, since the white display state is maintained in the normally white mode, the front contrast is lowered. Therefore, a light shielding layer such as a black matrix covering the region may be provided.

(Optical compensation layer)
The liquid crystal display device of the present invention is a liquid crystal display device in which a first optical compensation layer, a vertical alignment type liquid crystal cell, and a second optical compensation layer are arranged in this order, and the first optical compensation layer is a positive A plate. And the second optical compensation layer is a negative C plate layer.

  In the present application, the “positive A plate” refers to a birefringent layer that satisfies 0.9 ≦ Nz ≦ 1.1, and preferably satisfies 0.95 ≦ Nz ≦ 1.05. However, Nz is defined by the following formula.

Nz = (nx-ny) / (nz-ny)
Here, nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, and nz represents the refractive index in the thickness direction.

  On the other hand, the “negative C plate layer” refers to a retardation layer that satisfies nx = ny> nz. However, = means a substantially close value and does not need to be exactly equal.

  Preferably, 0 ≦ Ro ≦ 10, more preferably 0 ≦ Ro ≦ 5, and still more preferably 0 ≦ Ro ≦ 2.

  Here, the definition of the phase difference (Ro, Rt) is expressed by the following formula, and the above phase difference (retardation) values are all values measured at a wavelength of 550 nm.

Ro = (nx−ny) × d
Rt = {(nx + ny) / 2−nz} × d
In the present invention, the refractive index was determined in an environment of 23 ° C. and 55% RH using an Axoscan manufactured by Axometrcs.

  Similarly to the measurement of the refractive index, by measuring at 450 nm and 650 nm, the wavelength dispersion DSP (I) of the in-plane phase difference of the first optical compensation layer and the thickness direction position of the second optical compensation layer are measured. The wavelength dispersion DSP (II) of the phase difference was calculated.

  The form of the optical compensation layer is not limited, but is preferably a film from the viewpoint of handling.

<First optical compensation layer>
The first optical compensation layer according to the present invention is a positive A plate layer and needs to satisfy the following formula (3), and its form is not limited but is a film from the viewpoint of handling. Is preferred.
Formula (3): 0.6 ≦ DSP (I) ≦ 0.8
Here, DSP (I) is the ratio of the value Ro _{450 at} the wavelength 450 nm (Ro ₄₅₀ / Ro ₆₅₀ ) to the value Ro _{650 at} the wavelength 650 nm of the in-plane direction retardation of the first optical compensation layer.

  Examples of the film having such optical characteristics include a film mainly composed of a polymer having both a positive birefringent component and a negative birefringent component, for example, a polycarbonate (positive) copolymer having a fluorene skeleton (negative). A polymer stretched film mainly composed of a polymer (JP 2002-221622 A), a polymer stretched film mainly composed of styrene (negative) and polycarbonate (positive) (JP 2003-294492 A), Examples thereof include a stretched polymer film mainly composed of cycloolefin (positive) and styrene (negative). Moreover, the stretched film (for example, refer Unexamined-Japanese-Patent No. 2001-091743) of the polymer film which has a cellulose ester as a main component is mentioned. Specifically, Teijin Kasei Co., Ltd. pure ace etc. can be used. Details of the resin will be described later.

<Second optical compensation layer>
The second optical compensation layer according to the present invention is required to be a negative C plate layer satisfying the following formulas (4) and (5), and the form thereof is not limited, but is a film from the viewpoint of handling. Preferably there is.
Formula (4): DSP (II) ≦ −3.7x [DSP (LC) −DSP (CELL)] + 1.41
Formula (5): DSP (II) ≧ −1.1 × [DSP (LC) −DSP (CELL)] + 1.15
Here, DSP (II) is a ratio (Rt ₄₅₀ / Rt ₆₅₀ ) of the value Rt _{450 at} the wavelength 450 nm to the value Rt _{650 at} the wavelength 650 nm of the thickness direction retardation of the second optical compensation layer.

  The range that the above equation satisfies is shown in FIG. As is apparent from FIG. 2, within the range satisfying the above-mentioned formula (1), DSP (II) is always 1.04 ≦ DSP (II) ≦ regardless of [DSP (LC) −DSP (CELL)]. It is necessary to satisfy 1.37.

  Examples of the film satisfying such optical characteristics include stretched polymer films mainly composed of polycarbonate, cellulose, polyethylene, and polypropylene resins. Particularly preferred are cellulosic resins. Details of the resin base material will be described later.

In the present invention, the first optical compensation layer is disposed on the viewing side of the cell, the second optical compensation layer is disposed on the backlight side, and the in-plane retardation Ro at the wavelength of 550 nm of the first optical compensation layer. ₅₅₀ (I) and the thickness direction retardation Rt ₅₅₀ (II) at a wavelength of 550 nm of the second optical compensation layer is a liquid crystal display device in an embodiment satisfying the following formulas (R1) and (R2). It is preferable from the viewpoint of effect expression.
Formula (R1): 100 nm ≦ Ro ₅₅₀ (I) ≦ 200 nm
Formula (R2): 150 nm ≦ Rt ₅₅₀ (II) ≦ 250 nm
The relationship between [DSP (LC) -DSP (CELL)] and DSP (II) is within the range shown in FIG. 2, so that the polarization state in the oblique direction is compensated for all wavelengths, and light leakage in the oblique direction during black display is achieved. And a wide viewing angle can be achieved.

<Orientation variation coefficient>
In the present invention, the orientation variation coefficient X of the second optical compensation layer preferably satisfies the following formula.
Formula (X): 0.00000001 ≦ X ≦ 0.000001
In order to produce an optical compensation layer exhibiting such a variation coefficient, it is preferable to use a film-like optical compensation layer. The optical compensation film is produced, particularly 1.01 to 1 in the direction perpendicular to the conveying direction after peeling the web from the belt. It is preferable that the film is stretched by a factor of 1 and held without being relaxed after further stretching.

  The orientation variation coefficient according to the present invention can be calculated by measuring the phase difference R and the orientation angle θ at each point using a phase difference measuring device having a small spot diameter. For example, a birefringence measuring machine manufactured by Mizoji Optical Corporation can be used. A film is set, the in-plane retardation and the orientation direction are measured at a 1 mm pitch within the specified range, and the orientation unevenness X can be calculated from the following definition formula.

(Resin film substrate used for optical compensation layer)
As a material constituting the optical compensation layer according to the present invention, it is preferable to use a film-like resin substrate.

  As the resin film substrate according to the present invention, it is preferable to use a thermoplastic resin. Here, the “thermoplastic resin” refers to a resin that becomes soft when heated to the glass transition temperature or melting point and can be molded into a desired shape.

  General thermoplastic resins include cellulose esters, polyethylene (PE), high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene. (PS), polyvinyl acetate (PVAc), Teflon (registered trademark) (polytetrafluoroethylene, PTFE), ABS resin (acrylonitrile butadiene styrene resin), AS resin, acrylic resin (PMMA), etc., soluble in solvents It is preferable to dissolve the material appropriately and treat it by the method of the present invention.

  When strength and resistance to breakage are particularly required, polyamide (PA), nylon, polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE, modified PPE, PPO), polybutylene terephthalate (PBT) ), Polyethylene terephthalate (PET), glass fiber reinforced polyethylene terephthalate (GF-PET), cyclic polyolefin (COP), and the like.

  If higher heat distortion temperature and long-term use characteristics are required, polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone, polyethersulfone, amorphous polyarylate, liquid crystal polymer, polyetherether A ketone, thermoplastic polyimide (PI), polyamideimide (PAI), or the like can be used.

  In addition, it is possible to perform the kind of resin and the combination of molecular weight according to the use of this invention.

  The thickness of the optical compensation layer is preferably selected as appropriate according to the application. The upper limit of the thickness is not particularly limited, but in the case of forming a film by a solution casting method, the upper limit is about 150 μm from the viewpoint of applicability, foaming, solvent drying, and the like.

  The resin substrate preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.

  Hereinafter, a particularly preferred resin in the present invention will be described in detail.

<Cellulose ester resin>
The cellulose ester resin that can be used in the present invention is selected from cellulose (di, tri) acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose phthalate. It is preferable that there is at least one.

  Among these, particularly preferable cellulose esters include cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

  As a substitution degree of the mixed fatty acid ester, when having an acyl group having 2 to 4 carbon atoms as a substituent, when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group or butyryl group is Y, A cellulose resin containing a cellulose ester that simultaneously satisfies the following formulas (I) and (II) is preferable.

Formula (I) 2.0 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 2.5
Furthermore, the cellulose ester used in the present invention preferably has a weight average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 5.5, particularly preferably 2.0 to 5.0, Preferably it is 2.5-5.0, More preferably, the cellulose ester of 3.0-5.0 is used preferably.

  The cellulose ester raw material cellulose used in the present invention may be wood pulp or cotton linter, and the wood pulp may be softwood or hardwood, but softwood is more preferred. A cotton linter is preferably used from the viewpoint of peelability during film formation. The cellulose ester made from these can be mixed suitably or can be used independently.

  For example, the ratio of cellulose ester derived from cellulose linter: cellulose ester derived from wood pulp (coniferous): cellulose ester derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50: 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30.

  In the present invention, 1 g of cellulose ester resin is added to 20 ml of pure water (electric conductivity 0.1 μS / cm or less, pH 6.8), and the pH is 6 when stirred in a nitrogen atmosphere at 25 ° C. for 1 hr. It is preferable that the electric conductivity is 1 to 100 μS / cm.

《Sugar ester compound》
In the present invention, it is also preferable that the cellulose ester resin contains an ester compound having at least one pyranose structure or at least one furanose structure and having all or part of the OH groups in the structure esterified.

  The proportion of esterification is preferably 70% or more of the OH groups present in the pyranose structure or furanose structure.

  Examples of the ester compound according to the present invention include the following, but the present invention is not limited thereto.

  Glucose, galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable.

  Examples include sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, and more preferably sucrose.

  The monocarboxylic acid used for esterifying all or part of the OH groups in the pyranose structure or furanose structure of the present invention is not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, An aromatic monocarboxylic acid or the like can be used. The carboxylic acid used may be one type or a mixture of two or more types.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, Examples include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferable alicyclic monocarboxylic acids include acetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, and naphthalene. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralin carboxylic acid, or derivatives thereof. More specifically, xylyl acid, hemelic acid, mesitylene acid, prenylic acid, γ-isoduric acid, jurylic acid, mesitic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid , Creosote acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyroca Succinic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratromic acid, o-veratrumic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratrumic acid, o-homoveratrumic acid, phthalonic acid, p- Although coumaric acid can be mentioned, benzoic acid is particularly preferable.

  The oligosaccharide ester compound can be applied as a compound having 1 to 12 at least one of the pyranose structure or furanose structure according to the present invention.

  Oligosaccharides are produced by allowing an enzyme such as amylase to act on starch, sucrose, etc. Examples of oligosaccharides that can be applied to the present invention include maltooligosaccharides, isomaltoligosaccharides, fructooligosaccharides, galactooligosaccharides, xylooligos. Sugar.

Moreover, the said ester compound is a compound which condensed 1 or more and 12 or less of at least 1 sort (s) of the pyranose structure or furanose structure represented with the following general formula (A). However, R < ₁₁ > -R < ₁₅ >, R < ₂₁ > -R < ₂₅ > represents a C2-C22 acyl group or a hydrogen atom, m and n represent the integer of 0-12 respectively, and m + n represents the integer of 1-12.

R _{11 to} R ₁₅ and R _{21 to} R ₂₅ are preferably a benzoyl group or a hydrogen atom. The benzoyl group may further have a substituent R ₂₆ (p is 0 to 5), and examples thereof include an alkyl group, an alkenyl group, an alkoxyl group, and a phenyl group, and further, these alkyl groups, alkenyl groups, and phenyl groups. May have a substituent. Oligosaccharides can also be produced in the same manner as the ester compound according to the present invention.

  Although the specific example of the ester compound which concerns on this invention is given to the following, this invention is not limited to this.

  The cellulose ester film according to the present invention contains the sugar ester compound according to the present invention in an amount of 0.5 to 30% by mass of the cellulose ester film in order to suppress the fluctuation of the retardation value and stabilize the display quality. It is preferable to contain 5-30 mass% especially.

<acrylic resin>
The acrylic resin that can be used in the present invention includes a methacrylic resin. Although it does not restrict | limit especially as resin, What consists of 50-99 mass% of methyl methacrylate units and 1-50 mass% of other monomer units copolymerizable with this is preferable.

  Other monomers that can be copolymerized include alkyl methacrylates having 2 to 18 carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, acrylic acid, methacrylic acid, and the like. Saturated acids, maleic acids, fumaric acids, unsaturated divalent carboxylic acids such as itaconic acid, aromatic vinyl compounds such as styrene, α-methylstyrene, and nucleus-substituted styrene, α, β- such as acrylonitrile, methacrylonitrile, etc. Examples thereof include unsaturated nitrile, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, and the like. These may be used alone or in combination of two or more.

  Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable, and methyl acrylate and n-butyl acrylate are particularly preferably used.

  A commercially available thing can also be used as an acrylic resin. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Denki Kagaku Kogyo Co., Ltd.) and the like can be mentioned. .

<Cyclic olefin resin>
In the present invention, it is also preferable to use a cyclic olefin resin. Examples of the cyclic olefin resin include norbornene resins, monocyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, and hydrides thereof. Among these, norbornene-based resins can be suitably used because of their good transparency and moldability.

  Examples of the norbornene-based resin include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, and a norbornene structure. An addition polymer of a monomer having a monomer, an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof.

  Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Can be used.

Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene) and tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene. (Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0. 1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. In addition, these substituents may be the same or different and a plurality may be bonded to the ring. Monomers having a norbornene structure can be used singly or in combination of two or more.

  Examples of the polar group include a hetero atom or an atomic group having a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfone group.

  Other monomers capable of ring-opening copolymerization with monomers having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof, cyclic conjugated dienes such as cyclohexadiene, cycloheptadiene, and the like. And derivatives thereof.

  A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer of a monomer having a norbornene structure and another monomer copolymerizable with the monomer have a known ring-opening polymerization catalyst. It can be obtained by (co) polymerization in the presence.

  Examples of other monomers that can be addition copolymerized with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, Cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and the like. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferable and ethylene is more preferable.

  An addition polymer of a monomer having a norbornene structure and an addition copolymer of another monomer copolymerizable with a monomer having a norbornene structure can be used in the presence of a known addition polymerization catalyst. It can be obtained by polymerization.

  A hydrogenated product of a ring-opening polymer of a monomer having a norbornene structure, a hydrogenated product of a ring-opening copolymer of a monomer having a norbornene structure and another monomer capable of ring-opening copolymerization thereof, Hydrogenated products of addition polymers of monomers having a norbornene structure, and hydrogenated products of addition copolymers of monomers having a norbornene structure and other monomers capable of addition copolymerization with these A known hydrogenation catalyst containing a transition metal such as nickel or palladium is added to the polymer solution, and the carbon-carbon unsaturated bond is preferably hydrogenated by 90% or more.

Among norbornene-based resins, as repeating units, X: bicyclo [3.3.0] octane-2,4-diyl-ethylene structure and Y: tricyclo [4.3.0.1 ^2,5 ] decane-7 , 9-diyl-ethylene structure, the content of these repeating units is 90% by mass or more based on the entire repeating units of the norbornene resin, and the content ratio of X and the content ratio of Y The ratio of X: Y is preferably 100: 0 to 40:60. By using such a resin, it is possible to obtain an optical film that has no dimensional change in the long term and is excellent in stability of optical characteristics.

  The molecular weight of the cyclic olefin resin used in the present invention is appropriately selected according to the purpose of use. Polyisoprene or polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography using cyclohexane (toluene if the polymer resin does not dissolve) as a solvent, usually 20,000 to 150,000. . Preferably it is 25,000-100,000, More preferably, it is 30,000-80,000. When the weight average molecular weight is in such a range, the mechanical strength and molding processability of the film are highly balanced and suitable.

  The glass transition temperature of the cyclic olefin resin may be appropriately selected according to the purpose of use. From the viewpoint of durability and stretchability, it is preferably in the range of 130 to 160 ° C, more preferably 135 to 150 ° C.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the cyclic olefin resin is 1.2 to 3.5, preferably 1.5 to 3.0, from the viewpoint of relaxation time, productivity, and the like. More preferably, it is 1.8 to 2.7.

The cyclic olefin resin used in the present invention preferably has an absolute value of photoelastic coefficient of 10 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 7 × 10 ⁻¹² Pa ⁻¹ or less, and more preferably 4 × 10. It is particularly preferably ⁻¹² Pa ⁻¹ or less. The photoelastic coefficient C is a value represented by C = Δn / σ where birefringence is Δn and stress is σ.

  In the present invention, it is preferable that the cyclic olefin resin does not substantially contain particles. Here, “substantially free of particles” means that even if particles are added to a film made of a cyclic olefin resin, the amount of increase in haze from the non-added state is allowed to be in the range of 0.05% or less. Means you can. In particular, the alicyclic polyolefin resin lacks affinity with many organic particles and inorganic particles. Therefore, when a cyclic olefin resin film to which particles exceeding the above range are added is stretched, voids are easily generated, and as a result, There is a risk that a significant decrease in haze occurs.

<Polycarbonate resin>
In the present invention, various known polycarbonate resins can also be used. In the present invention, it is particularly preferable to use an aromatic polycarbonate. There is no restriction | limiting in particular about the said aromatic polycarbonate, and there will be no restriction | limiting in particular if it is an aromatic polycarbonate from which the various characteristics of a desired film are acquired.

  In general, a polymer material collectively referred to as polycarbonate is a generic term for a polymer material in which a polycondensation reaction is used in its synthesis method and the main chain is linked by a carbonic acid bond. , Phosgene, diphenyl carbonate and the like obtained by polycondensation. Usually, an aromatic polycarbonate represented by a repeating unit having 2,2-bis (4-hydroxyphenyl) propane called bisphenol-A as a bisphenol component is preferably selected, and various bisphenol derivatives should be appropriately selected. Thus, an aromatic polycarbonate copolymer can be constituted.

  In addition to this bisphenol-A, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 1,1 -Bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxyphenyl) -2-phenyl Ethane, 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) sulfide, bis ( 4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) -3,3,5-tri Mention may be made of a chill cyclohexane, and the like.

  It is also possible to use an aromatic polyester carbonate partially containing terephthalic acid and / or isophthalic acid components. By using such a structural unit as a part of the structural component of the aromatic polycarbonate composed of bisphenol-A, the properties of the aromatic polycarbonate, such as heat resistance and solubility, can be improved. The present invention is also effective for coalescence.

  If the aromatic polycarbonate used here has a viscosity average molecular weight of 10,000 or more and 200,000 or less, it is suitably used. A viscosity average molecular weight of 20,000 to 120,000 is particularly preferred. If a resin having a viscosity average molecular weight lower than 10,000 is used, the mechanical strength of the resulting film may be insufficient, and if it has a high molecular weight of 400000 or more, the viscosity of the dope becomes too large, causing problems in handling. The viscosity average molecular weight can be measured by commercially available high performance liquid chromatography.

  The glass transition temperature of the aromatic polycarbonate according to the present invention is preferably 200 ° C. or higher in order to obtain a highly heat-resistant film, and more preferably 230 ° C. or higher. These can be obtained by appropriately selecting the copolymerization component. The glass transition temperature can be measured with a DSC apparatus (differential scanning calorimetric analyzer). For example, the baseline is unevenly determined by a temperature rising condition of 10 ° C./min with RDC220 manufactured by Seiko Instruments Inc. It is the temperature that begins to do.

  In the present invention, the solvent used for the dope composition containing the aromatic polycarbonate is a mixed solvent containing 4 to 14 parts by mass of methylene chloride and a linear or branched aliphatic alcohol having 1 to 6 carbon atoms. It is preferable.

  The mixing amount of the linear or branched aliphatic alcohol having 1 to 6 carbon atoms is preferably 4 to 12 parts by mass. By using such a mixed solvent, the web is peeled off at a higher residual solvent concentration than before, thereby suppressing the generation of strong static electricity when the web is peeled off, thereby causing damage to the belt, film streaks, unevenness, Scratches can be prevented from occurring.

  The type of alcohol added is limited by the solvent used. It is a necessary condition that the alcohol and the solvent are compatible. These may be added alone or in combination of two or more. The alcohol in the present invention is preferably a linear or branched aliphatic alcohol having 1 to 6, preferably 1 to 4, more preferably 2 to 4 carbon atoms. Specific examples include methanol, ethanol, isopropanol, and tert-butanol. Of these, ethanol, isopropanol, and tertiary-butanol can achieve almost the same effect, but methanol has a slightly lower effect. Although the reason is not clear, it is presumed that the boiling point of the solvent, that is, the ease of flying during drying is related. Higher alcohols higher than that are not preferred because they have a high boiling point and are likely to remain after film formation.

  The amount of alcohol added must be carefully selected. These alcohols are completely poor in solubility in aromatic polycarbonate and are completely poor solvents. Therefore, it cannot be added too much, and should be the minimum amount that provides satisfactory peelability. As mentioned above, it is 4-14 mass parts with respect to a methylene chloride, Preferably it is 4-12 mass parts. When the addition amount is in the range of 4 to 14 parts by mass with respect to the amount of methylene chloride, the solubility of the solvent in the polymer and the dope stability are improved, and the effect of improving the peelability is increased.

  The present invention comprises the above methylene chloride and aliphatic alcohol in the dope composition, but other solvents can also be used. The remaining solvent is not particularly limited as long as it dissolves the aromatic polycarbonate at a high concentration and is compatible with alcohol, and is a low-boiling solvent. For example, as a solvent having a solubility in an aromatic polycarbonate, in addition to methylene chloride, halogen solvents such as chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene, 1,3-dioxolane, 1, Examples include cyclic ether solvents such as 4-dioxane and tetrahydrofuran, and ketone solvents such as cyclohexanone.

  When using other solvent, there is no limitation in particular and it may use it in consideration of an effect. The effects here include mixing the solvent without sacrificing solubility and stability, for example, improving the surface properties of the film formed by the solution casting method (leveling effect), evaporation rate and system These include viscosity adjustment and crystallization suppression effects. What is necessary is just to determine the kind and addition amount of the solvent to mix by the degree of these effects, and you may use 1 type, or 2 or more types as a solvent to mix.

  Other solvents preferably used include halogen solvents such as chloroform and 1,2-dichloroethane, hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone, and ethyl acetate and butyl acetate. Examples include ester solvents, ether solvents such as ethylene glycol dimethyl ether and methoxyethyl acetate.

  The dope composition according to the present invention may be prepared by any method as long as a transparent solution having a low haze is obtained as a result. A predetermined amount of alcohol may be added to the aromatic polycarbonate solution dissolved in a certain solvent in advance, or the aromatic polycarbonate may be dissolved in a mixed solvent containing alcohol. However, as described above, since alcohol is a poor solvent, the method of adding the latter after the former may cause clouding of the dope due to the precipitation of the polymer. Therefore, the method of dissolving in the latter mixed solvent is preferable.

<Polyester resin>
The polyester resin that can be used in the present invention is obtained by polymerizing a dicarboxylic acid and a diol, and 70% or more of dicarboxylic acid structural units (constituent units derived from dicarboxylic acid) are derived from aromatic dicarboxylic acid, and 70% or more of the diol constituent units (constituent units derived from the diol) are derived from the aliphatic diol.

  The proportion of the structural unit derived from the aromatic dicarboxylic acid is 70% or more, preferably 80% or more, more preferably 90% or more.

  The proportion of the structural unit derived from the aliphatic diol is 70% or more, preferably 80% or more, and more preferably 90% or more. Two or more polyester resins may be used in combination.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, naphthalenedicarboxylic acid such as 2,7-naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid. 3,4'-biphenyldicarboxylic acid and the like and ester-forming derivatives thereof.

  As the polyester resin, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, and monocarboxylic acids such as benzoic acid, propionic acid, and butyric acid can be used without departing from the object of the present invention.

  Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, and the like, and ester-forming derivatives thereof.

  As the polyester resin, monoalcohols such as butyl alcohol, hexyl alcohol, and octyl alcohol, and polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol can be used as long as the object of the present invention is not impaired.

  A known esterification method or transesterification method can be applied to the production of the polyester resin. Examples of the polycondensation catalyst used in the production of the polyester resin include known antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. Although it can, it is not limited to these.

  Preferred polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalene dicarboxylate resin, polyethylene-2, 6-naphthalene dicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4'-biphenyldicarboxylate resin, poly-1,3-propylene-terephthalate resin, polybutylene terephthalate resin, polybutylene-2,6-naphthalene There are dicarboxylate resins and the like.

  More preferable polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin, and polyethylene-2,6-naphthalene dicarboxylate. Resin.

  The intrinsic viscosity of the polyester resin (phenol / 1,1,2,2-tetrachloroethane = value measured at 25 ° C. in a 60/40 mass ratio mixed solvent) is preferably 0.7 to 2.0 dl / g, more Preferably it is 0.8-1.5 dl / g. Since the molecular weight of the polyester resin is sufficiently high when the intrinsic viscosity is 0.7 or more, the molded product comprising the polyester resin composition obtained by using the polyester resin has mechanical properties necessary for the molded product and is transparent. Property is improved. When the intrinsic viscosity is 2.0 or less, the moldability is good.

(Other additives)
The thermoplastic resin substrate according to the present invention can contain various compounds as additives depending on the purpose. For example, a plasticizer, an antioxidant, an acid scavenger, a light stabilizer, an ultraviolet absorber, an optical anisotropy control agent, a matting agent, an antistatic agent, a release agent, and the like can be contained.

  Among the additives, it is an optical anisotropy control agent that effectively contributes to the present invention, and in particular, the retardation increasing agent makes it easy to optically exhibit birefringence obliquely from the plane of the present application. Therefore, it is preferable. The retardation increasing agent is preferably an aromatic compound having at least two aromatic rings. The aromatic compound is preferably used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the resin. And it is preferable to use in 0.05-15 mass parts, and it is still more preferable to use in 0.1-10 mass parts. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. Details of these are described in JP-A No. 2004-109410, JP-A No. 2003-344655, JP-A No. 2000-275434, JP-A No. 2000-1111914, JP-A No. 12-275434, and the like.

(Matting agent)
The thermoplastic resin substrate according to the present invention may be added with fine particles as a matting agent in order to prevent scratching or deterioration of transportability when the produced film is handled. preferable.

  As fine particles, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples thereof include magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable. The content of these fine particles in the film is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass. In the case of an optical film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

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

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

  Examples of the resin include a silicone resin, a fluororesin, and an acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the haze of the optical film low. In the optical film according to the present invention, the dynamic friction coefficient of at least one surface is preferably 0.2 to 1.0.

(Manufacturing method of optical film constituting optical compensation layer)
As a method for producing the resin film substrate according to the present invention as a film, production methods such as a normal inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, and a hot press method can be used. However, the solution casting method and the melt casting method by a casting method are preferable from the viewpoints of suppressing coloring, suppressing defects of foreign matters, and suppressing optical defects such as die lines.

  Hereinafter, the manufacturing method in the case of producing the optical film which concerns on this invention is explained in full detail.

<Method for producing optical film by solution casting method>
《Organic solvent》
When the optical film according to the present invention is produced by a solution casting method, an organic solvent useful for forming a dope can be used without limitation as long as it dissolves a thermoplastic resin such as a cellulose ester resin.

  For example, as the chlorinated organic solvent, methylene chloride, as the non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, ethyl lactate, lactic acid , Diacetone alcohol and the like, methylene chloride, methyl acetate, ethyl acetate, acetone, ethyl lactate and the like are preferably used. That.

  In addition to the organic solvent, the dope may contain 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels, facilitating peeling from the metal support, and when the proportion of alcohol is small, the dissolution of the thermoplastic resin in a non-chlorine organic solvent system is promoted. There is also a role.

  In particular, the thermoplastic resin should be a dope composition in which at least a total of 10 to 45 mass% is dissolved in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. preferable.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

  Hereinafter, a preferable method for forming an optical film according to the present invention (hereinafter also simply referred to as “film”) will be described.

1) Dissolution Step In this step, a thermoplastic resin and other additives are dissolved in an organic solvent mainly composed of a good solvent for the thermoplastic resin while stirring to form a dope.

  For the dissolution of the thermoplastic resin, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557 Alternatively, various dissolution methods such as a cooling dissolution method as described in JP-A-9-95538 and a high-pressure method as described in JP-A-11-21379 can be used. The method of pressurizing at a boiling point or higher is preferred.

  Recycled material is a finely pulverized film, which is generated when the film is formed, cut off on both sides of the film, or the original film that has been speculated out due to scratches, etc. Reused.

2) Casting process An endless metal belt, such as a stainless steel belt or a rotating metal drum, which supports the dope is fed to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump) and supported infinitely. This is a step of casting a dope from a pressure die slit to a casting position on the body.

  A pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.

3) Solvent evaporation step In this step, the web (the dope is cast on the casting support and the formed dope film is called a web) is heated on the casting support to evaporate the solvent.

  To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the support by a liquid, a method of transferring heat from the front and back by radiant heat, etc. High efficiency and preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or to heat by means such as infrared rays.

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

4) Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process.

  The temperature at the peeling position on the metal support is preferably 10 to 40 ° C, more preferably 11 to 30 ° C.

  In addition, it is preferable that the residual solvent amount at the time of peeling of the web on the metal support at the time of peeling is peeled in the range of 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like. If the web is peeled off at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling will be lost, and slippage and vertical stripes are likely to occur due to the peeling tension. The amount of solvent is determined.

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

Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension at the time of peeling the metal support and the film is usually 196 to 245 N / m. However, when wrinkles easily occur at the time of peeling, it is preferable to peel with a tension of 190 N / m or less. It is preferable to peel at a minimum tension that can be peeled to 166.6 N / m, and then peel at a minimum tension to 137.2 N / m, and particularly preferably peel at a minimum tension to 100 N / m.

  In the present invention, the temperature at the peeling position on the metal support is preferably -50 to 40 ° C, more preferably 10 to 40 ° C, and most preferably 15 to 30 ° C.

5) Drying and stretching step After peeling, using a drying device that alternately passes the web through rolls arranged in the drying device and / or a tenter stretching device that clips and transports both ends of the web with clips. Dry the web.

  Generally, the drying means blows hot air on both sides of the web, but there is also a means for heating by applying microwaves instead of the wind. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout the drying is generally carried out at 40-250 ° C. It is particularly preferable to dry at 40 to 160 ° C.

  When using a tenter stretching apparatus, it is preferable to use an apparatus that can independently control the film gripping length (distance from the start of gripping to the end of gripping) left and right by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create sections having different temperatures in order to improve planarity.

  It is also preferable to provide a neutral zone between different temperature zones so that the zones do not interfere with each other.

  In addition, extending | stretching operation may be divided | segmented and implemented in multiple steps, and it is also preferable to implement biaxial stretching in a casting direction and a width direction. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise.

  In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible. That is, for example, the following stretching steps are possible.

-Stretch in the casting direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction-Stretch in the width direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferable draw ratio of simultaneous biaxial stretching can be taken in the range of x1.01 times to x1.5 times in both the width direction and the longitudinal direction.

  When the tenter is used, the residual solvent amount of the web is preferably 20 to 100% by mass at the start of the tenter, and it is preferable to perform drying while applying the tenter until the residual solvent amount of the web becomes 10% by mass or less. More preferably, it is 5% by mass or less.

  30-160 degreeC is preferable, as for the drying temperature in the case of performing a tenter, 50-150 degreeC is more preferable, and 70-140 degreeC is the most preferable.

  In the tenter process, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the film. The temperature distribution in the width direction in the tenter process is preferably within ± 5 ° C, and within ± 2 ° C Is more preferable, and within ± 1 ° C. is most preferable.

6) Winding step This is a step of winding the film as a film by a winder after the amount of residual solvent in the web is 2% by mass or less. By reducing the amount of residual solvent to 0.4% by mass or less, dimensional stability can be improved. A good film can be obtained. It is particularly preferable to wind up at 0.00 to 0.10% by mass.

  As a winding method, a generally used method may be used. There are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

  The film according to the present invention is preferably a long film. Specifically, the film has a thickness of about 100 m to 5000 m and is usually provided in a roll shape. Moreover, it is preferable that the width | variety of a film is 1.3-4m, and it is more preferable that it is 1.4-2m.

  Although there is no restriction | limiting in particular in the film thickness of the film concerning this invention, It is preferable that it is 20-200 micrometers, It is more preferable that it is 25-150 micrometers, It is especially preferable that it is 30-120 micrometers.

<Method for producing optical film by melt casting method>
A method for producing the resin film substrate according to the present invention as an optical film by a melt casting film forming method will be described.

<Melted pellet manufacturing process>
The composition constituting the thermoplastic resin film used for melt extrusion is usually preferably kneaded in advance and pelletized.

  Pelletization may be performed by a known method. For example, a dry thermoplastic resin and an additive depending on the purpose are supplied to an extruder with a feeder, and kneaded using a single-screw or twin-screw extruder. Extruded into a shape, water-cooled or air-cooled and cut.

  It is important to dry the raw material before extruding to prevent decomposition of the raw material. In particular, since the cellulose ester easily absorbs moisture, it is preferable to dry it at 70 to 140 ° C. for 3 hours or more with a dehumidifying hot air dryer or a vacuum dryer to keep the moisture content at 200 ppm or less, and further 100 ppm or less.

  Additives may be fed into the extruder and fed into the extruder, or may be fed by individual feeders. In order to mix a small amount of additives such as an antioxidant uniformly, it is preferable to mix them in advance.

  The antioxidant may be mixed with each other, and if necessary, the antioxidant may be dissolved in a solvent, impregnated with a thermoplastic resin and mixed, or mixed by spraying. May be.

A vacuum nauter mixer or the like is preferable because drying and mixing can be performed simultaneously. Further, if the contact with air, such as the exit from the feeder unit or die, it is preferable that the atmosphere such as dehumidified air and dehumidified N ₂ gas.

  The extruder is preferably processed at as low a temperature as possible so that the shearing force is suppressed and the resin can be pelletized so as not to deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. It is also possible to feed the raw material powder directly to the extruder with a feeder and form a film as it is without pelletization.

<Process for extruding molten mixture from die to cooling roll>
First, using a single-screw or twin-screw type extruder, the melt temperature Tm when extruding the pellet is about 200 to 300 ° C., filtered through a leaf disk type filter or the like to remove foreign matters, The film is coextruded into a film, solidified on a cooling roll, and cast while pressing with an elastic touch roll.

  When introducing into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition and the like under vacuum, reduced pressure, or inert gas atmosphere. Tm is the temperature of the die exit portion of the extruder.

  When foreign matter such as scratches or plasticizer aggregates adheres to the die, streak-like defects may occur. Such defects are also referred to as die lines, but in order to reduce surface defects such as die lines, it is preferable to have a structure in which the resin retention portion is minimized in the piping from the extruder to the die. . It is preferable to use a die that has as few scratches as possible inside the lip.

  The inner surface that contacts the molten resin such as an extruder or a die is preferably subjected to surface treatment that makes it difficult for the molten resin to adhere to the surface by reducing the surface roughness or using a material having a low surface energy. Specifically, a hard chrome plated or ceramic sprayed material is polished so that the surface roughness is 0.2 S or less.

  In the present invention, there is no particular limitation on the cooling roll, but it is a roll having a structure in which a heat medium or a coolant that can be controlled in temperature flows with a highly rigid metal roll, and the size is not limited. It is sufficient that the film is large enough to cool the film, and the diameter of the cooling roll is usually about 100 mm to 1 m.

  Examples of the surface material of the cooling roll include carbon steel, stainless steel, aluminum, and titanium. Further, in order to increase the hardness of the surface or improve the releasability from the resin, it is preferable to perform a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, or ceramic spraying.

  The surface roughness of the chill roll surface is preferably 0.1 μm or less in terms of Ra, and more preferably 0.05 μm or less. The smoother the roll surface, the smoother the surface of the resulting film. Of course, it is preferable that the surface processed is further polished to have the above-described surface roughness.

  In the present invention, examples of the elastic touch roll include JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, WO97-028950, JP-A-11-235747, A silicon rubber roll coated with a thin film metal sleeve can be used as described in Japanese Unexamined Patent Application Publication No. 2002-36332, Japanese Patent Application Laid-Open No. 2005-172940 and Japanese Patent Application Laid-Open No. 2005-280217.

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

<Extension process>
In the present invention, the film obtained as described above can be further stretched 1.01 to 3.0 times in at least one direction after passing through the step of contacting the cooling roll.

  Preferably, the film is stretched 1.1 to 2.0 times in both the longitudinal (film transport direction) and lateral (width direction) directions.

  As a method of stretching, a known roll stretching machine or tenter can be preferably used. In particular, when the optical film also serves as a polarizing plate protective film, it is preferable to stack the polarizing film in a roll form by setting the stretching direction to the width direction.

  By stretching in the width direction, the slow axis of the optical film becomes the width direction.

  Usually, the draw ratio is 1.1 to 3.0 times, preferably 1.2 to 1.5 times, and the draw temperature is usually Tg to Tg + 50 ° C. of the resin constituting the film, preferably Tg to Tg + 50 ° C. In the temperature range.

  The stretching is preferably performed under a uniform temperature distribution controlled in the longitudinal direction or the width direction. The temperature is preferably within ± 2 ° C, more preferably within ± 1 ° C, and particularly preferably within ± 0.5 ° C.

  When the film-shaped resin film produced by the above method is used as an optical film, the film may be contracted in the longitudinal direction or the width direction for the purpose of reducing the retardation of the optical film and reducing the dimensional change rate.

  In order to shrink in the longitudinal direction, for example, there is a method in which the film is shrunk by temporarily clipping out the width stretching and relaxing in the longitudinal direction, or by gradually narrowing the interval between adjacent clips of the transverse stretching machine.

  The uniformity in the slow axis direction is also important, and the angle is preferably −5 to + 5 ° with respect to the film width direction, more preferably in the range of −1 to + 1 °, and particularly −0. It is preferably in the range of 5 to + 0.5 °, particularly preferably in the range of −0.1 to + 0.1 °. These variations can be achieved by optimizing the stretching conditions.

  The optical film of the present invention is preferably a long film. Specifically, the optical film has a thickness of about 100 m to 5000 m and is usually provided in a roll shape. Moreover, it is preferable that the width | variety of a film is 1.3-4m, and it is more preferable that it is 1.4-2m.

  There is no restriction | limiting in particular in the film thickness of the film-form resin film which concerns on this invention, It is preferable to change according to the objective. For example, when using for a polarizing plate protective film, it is preferable that it is 20-200 micrometers, It is more preferable that it is 25-150 micrometers, It is especially preferable that it is 30-120 micrometers.

(Polarizer)
When using the optical film which concerns on this invention as a protective film for polarizing plates, a polarizing plate can be produced by a general method. It is preferable that an adhesive layer is provided on the back side of the optical film according to the present invention, and is bonded to at least one surface of a polarizer produced by immersing and stretching in an iodine solution.

  On the other surface, the optical film of the present invention may be used, or another polarizing plate protective film may be used. For example, a commercially available cellulose ester film (for example, Konica Minoltack KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KC4R-4, KC4FR-3, KC4FR-3, KC4FR-3, KC4FR-3, KC4FR-3, KC4FR-3, -1, KC8UY-HA, KC8UX-RHA, manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used.

  A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed.

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

As the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer, a pressure-sensitive adhesive having a storage elastic modulus at 25 ° C. in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ⁹ Pa in at least a part of the pressure-sensitive adhesive layer is used. Preferably, a curable pressure-sensitive adhesive that forms a high molecular weight body or a crosslinked structure by various chemical reactions after the pressure-sensitive adhesive is applied and bonded is suitably used.

  Specific examples include, for example, urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, curable adhesives such as thermosetting acrylic adhesives, moisture-curing urethane adhesives, polyether methacrylate types, Examples include anaerobic pressure-sensitive adhesives such as ester-based methacrylate type and oxidized polyether methacrylate, cyanoacrylate-based instantaneous pressure-sensitive adhesives, and acrylate-peroxide-based two-component instantaneous pressure-sensitive adhesives.

  The pressure-sensitive adhesive may be a one-component type or a type in which two or more components are mixed before use.

  The pressure-sensitive adhesive may be a solvent system using an organic solvent as a medium, or may be an aqueous system such as an emulsion type, a colloidal dispersion type, or an aqueous solution type that is a medium containing water as a main component. It may be a solventless type. The density | concentration of the said adhesive liquid should just be suitably determined with the film thickness after adhesion, the coating method, the coating conditions, etc., and is 0.1-50 mass% normally.

(Manufacturing method of liquid crystal display device)
The film having a defined alignment variation coefficient is particularly preferably used for a liquid crystal display device manufactured by a roll-to-panel manufacturing method.

In this application, the “roll-to-panel manufacturing method” means that a roll-shaped long polarizing plate is not cut into a liquid crystal cell size in advance, and the polarizing plate is fed directly from the roll and bonded to the liquid crystal cell, and then a laser cutter. In this method, the liquid crystal cell size is cut (see FIG. 3). In this case, a bonding roll is pressed when the polarizing plate is bonded to the liquid crystal cell. However, since it is a long polarizing plate, an unreasonable force is easily applied at the time of bonding, and unevenness is likely to occur in the polarizing plate. Therefore, in the case of this manufacturing method, it is preferable to use a film having an orientation variation defined in the present invention.
[Example]
Hereinafter, although an example is given and the present invention is explained, the present invention is not limited to these.

<< Production of optical compensation film >>
<Optical compensation film A1>
The product name “Pure Ace” manufactured by Teijin Kasei Co., Ltd. was stretched by heating. The thickness was 50 μm, Ro was 135 nm, Nz = 1.0, and DSP (I) = 0.70.

  The refractive index, the retardation value, and the wavelength dispersion DSP (I) were measured using an Axoscan manufactured by Axometers under an environment of 23 ° C. and 55% RH at measurement light wavelengths of 450 nm and 650 nm. It measured similarly about the following films.

<Optical compensation film A2>
Produced by heating and stretching a commercial name "Pure Ace" manufactured by Teijin Chemicals Limited. The thickness was 35 μm, Ro was 90 nm, Nz = 1.0, and DSP (I) = 0.70.

<Optical compensation film A3-5>
Films were produced in accordance with the production of optical films B1, 2, and 3 described in JP-A-2008-242258, and designated as optical compensation films A3, 4, and 5.

Production of Optical Compensation Film A3 Polymer film mainly composed of cycloolefin resin obtained by hydrogenating a ring-opening polymer of norbornene monomer [trade name “Zeonor ZF14-100” manufactured by Nippon Zeon Co., Ltd.] (average refractive index = 1 .51, Ro [590] = 2.0 nm, Rt [590] = 8.0 nm); Biaxially stretched polypropylene film [manufactured by Toray Industries, Inc., trade name “Trefan E60-high shrinkage” on both sides of thickness 100 μm] “Type” (thickness 60 μm)] was bonded through an acrylic pressure-sensitive adhesive layer (thickness 15 μm). Then, the longitudinal direction of the film was held with a roll stretching machine, and the film was stretched 1.40 times in an air circulation drying oven at 148 ° C. ± 1 ° C. (temperature measured at a distance of 3 cm from the film back surface). Then, the optical film B1 was produced by cutting out a film, hold | gripping four sides, and extending | stretching 1.25 times in the direction orthogonal to the extending | stretching direction of a roll extending machine.

  In addition, the shrinkage rate at 140 ° C. of the biaxially stretched polypropylene film used for producing the optical film B1 was 6.4% in the MD direction and 12.8% in the TD direction. The acrylic pressure-sensitive adhesive uses isononyl acrylate (weight average molecular weight = 550,000) synthesized by solution polymerization as a base polymer, and 100 parts by mass of the polymer, a polyisocyanate compound crosslinking agent [Nippon Polyurethane ( Co., Ltd. product name “Coronate L”] 3 parts by mass and catalyst [Tokyo Fine Chemicals Co., Ltd. product name “OL-1”] 10 parts by mass were used.

Production of Optical Compensation Film A4 With reference to the method described in Examples of Japanese Patent Application Laid-Open No. 2006-188671, resin P2 described in the publication was produced.

  This resin P2 was formed into a film by a methylene chloride cast method to obtain a colorless and transparent cast film having a thickness of 100 μm and a residual solvent amount of 0.2% or less. This film was heated to 195 ° C., stretched 2.0 times at a stretching rate of 220% / min, then cooled and taken out to produce an optical compensation film A4.

Production of Optical Compensation Film A5 A modified polycarbonate trade name “WRF” (manufactured by Teijin Limited) was biaxially stretched to produce an optical compensation film A5.

<Optical compensation film A6>
A commercial name “KA film” manufactured by Kaneka Corporation was used. The thickness was 100 μm, Ro was 140 nm, Nz = 1.0, and DSP (I) = 0.97.

<Optical compensation film A7>
<Fine particle dispersion>
Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
Cellulose ester was added to a dissolution tank containing methylene chloride, and heated to completely dissolve, then, this was added to Azumi filter paper No. 3 manufactured by Azumi Filter Paper Co., Ltd. Filtered using 244.

  The fine particle dispersion was slowly added thereto while sufficiently stirring the filtered cellulose ester solution. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by weight Cellulose ester (acetyl group substitution degree 1.6, propionyl group substitution degree 0.9, total acyl group substitution degree 2.7) 4 parts by weight Fine particle dispersion 11 parts by weight Prepare a main dope solution having the following composition did. First, methylene chloride and ethanol were added to the pressure dissolution tank. The cellulose ester was added to the pressure dissolution tank containing the solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of main dope solution 1>
Methylene chloride 380 parts by mass Ethanol 70 parts by mass Cellulose ester (acetyl group substitution degree 1.6, propionyl group substitution degree 0.9, total acyl group substitution degree 2.7) 100 parts by mass (meth) acrylic polymer A3. 0 parts by mass Sugar ester compound A (Exemplary Compound 3) 5.5 parts by mass The above is put into a sealed container, heated and stirred to dissolve completely, and Azumi Filter Paper No. No. 24 was used for filtration to prepare a dope solution.

  The dope solution was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. in the film production line. In the in-line additive solution line, the fine particle additive solution 1 was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. 2 parts by mass of the filtered fine particle additive 1 is added to 100 parts by mass of the filtered dope solution and sufficiently mixed with an in-line mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ), and then a belt casting apparatus. Was cast uniformly onto a stainless steel band support at a temperature of 35 ° C. and a width of 2 m. With the stainless steel band support, the solvent was evaporated until the residual solvent amount became 120%, and then peeled off from the stainless steel band support. The peeled cellulose ester web was evaporated at 50 ° C., slit to a width of 1.65 m, and then contracted in the MD direction (longitudinal direction) with a tenter at the same time in the TD direction (film length). The film was stretched 1.5 times (50%) at 180 ° C. in a direction perpendicular to the conveying direction. Drying was completed while transporting the 120 ° C. drying zone with many rolls, slitting to a width of 2000 mm, and knurling with a width of 15 mm and an average height of 10 μm was applied to both ends of the film to produce a film A7. The film width was 1.5 m, the winding length was 5000 m, the film thickness was 60 μm, Ro = 135 nm, and Nz = 1.0.

  The following are the materials used in the examples.

  (Meth) acrylic polymer A: Bulk polymerization was carried out by the polymerization method described in JP-A No. 2000-128911. That is, methyl acrylate was introduced as a monomer into a flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, an inlet, and a reflux condenser, and nitrogen gas was introduced and the inside of the flask was replaced with nitrogen gas while stirring. Added.

  After the addition of thioglycerol, polymerization was carried out for 4 hours, the contents were returned to room temperature, and 20 parts by mass of a 5% by mass benzoquinone tetrahydrofuran solution was added thereto to stop the polymerization. The contents were transferred to an evaporator, and tetrahydrofuran, residual monomer and residual thioglycerol were removed under reduced pressure at 80 ° C. to obtain a (meth) acrylic polymer A having a molecular weight of 1000.

Sugar ester compound A: Sugar ester compound exemplified compound 3
<Optical compensation film B1>
<Composition of main dope solution B>
10. Methylene chloride 380 parts by mass Ethanol 70 parts by mass Cellulose ester (acetyl group substitution degree 2.80) 100 parts by mass Triazine compound 5.3 parts by mass Sugar ester compound A (Exemplary compound 3) 5.5 parts by mass Fine particle dispersion 11. 2 parts by mass or more were put into a sealed container, heated and stirred, and completely dissolved. Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. No. 24 was used for filtration to prepare a dope solution.

  The dope solution was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. in the film production line. Next, using a belt casting apparatus, the belt was uniformly cast on a stainless steel band support at a temperature of 35 ° C. and a width of 2 m. With the stainless steel band support, the solvent was evaporated until the residual solvent amount became 30%, and the stainless steel band support was peeled off. Then, it extended | stretched to 1.04 (4%) at 125 to the TD direction (direction orthogonal to the conveyance direction of a film). Drying was terminated while transporting the 125 ° C. drying zone with a number of rolls, slitting to a width of 2000 mm, and knurling with a width of 15 mm and an average height of 10 μm was applied to both ends of the film to produce a film B1. The film width was 1.5 m, the winding length was 3000 m, the thickness was 80 μm, Ro was 0 nm, Rt = 190 nm, and DSP (II) = 1.19.

<Optical compensation film B2-4>
In the production of the optical compensation film B1, optical compensation films B2 to B4 were produced in the same manner except that the stretching conditions and the film thickness were changed as shown in Table 1.

<Optical compensation film B5-6>
Films were produced according to the production of optical films A1 and A2 described in JP-A-2008-242258, and optical compensation films B5 and 6 were obtained.

Preparation of Optical Compensation Film B5 A cellulose acylate film (TAC-TD80U manufactured by FUJIFILM Corporation) was prepared.

  Separately, polyimide having the following structure (λmax: range of 260 to 350 nm; weight average molecular weight (Mw) 120,000) was dissolved in cyclohexanone to prepare a 9.5% cyclohexanone solution.

  This solution was applied to the surface of a cellulose acylate film and dried at 100 ° C. for 5 minutes to form a polyimide layer. The thickness of the polyimide layer was 1.6 μm.

Production of Optical Compensation Film B6 Each component shown in the following table was mixed to prepare a cellulose acylate composition. This was extruded from a die at a screw rotation speed of 300 rpm, a kneading time of 40 seconds, and an extrusion rate of 200 kg / hr, solidified in water at 60 ° C., and then cut, 2 mm in diameter and 3 mm in length. Columnar pellets were obtained. Thereafter, using the pellets, a melt film was formed in the same manner as in Example 1 of JP2007-2216A to obtain an 80 μm film. This film was biaxially stretched at 150 ° C. to obtain a cellulose acylate film. A polyimide layer was formed in the same manner except that this cellulose acylate film was used instead of TAC-TD80U, and an optical compensation film B6 was produced. The thickness of the polyimide layer was 1.6 μm.

<Optical compensation film B7>
Commercially available JSR Co., Ltd. product name “ARTON film” was dry stretched 1.15 times at 175 ° C. in the longitudinal direction, and then 1.335 times dry stretched at 175 ° C. in the width direction (direction perpendicular to the longitudinal direction). The two films prepared by relaxing the length in the longitudinal direction to be 0.975 times the length in the width direction after the stretching treatment were bonded via an adhesive to obtain an optical compensation film B7. . The thickness was 75 μm, R0 = 0 nm, Rt = 180 nm, and DSP (II) = 1.01.

<Optical compensation film B8-14>
In the production of the optical compensation film B1, as described in Table 2, except that the amount of the cellulose acetate species and the additive (triazine compound) was changed, the film thickness and the stretching temperature were appropriately adjusted to adjust the film thickness and the stretching temperature as appropriate. 14 was produced. The film thickness and chromatic dispersion were as shown in Table 2, and all the phase differences were Ro = 0 nm and Rt = 190 nm.

<Preparation of polarizing plates PA4, PA6, PA7, PB1-15>
A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. consisting of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

  Next, according to the following steps 1 to 5, optical compensation films A4, A6, A7, B1 to 15 are provided on the front side of the polarizer, and Konica Minolta Tack KC4UY (cellulose ester film manufactured by Konica Minolta Opto Co., Ltd.) is provided on the back side. ) Were each bonded as a polarizing plate protective film to prepare polarizing plates PA4, PA6, PA7, and PB1-15. However, the optical compensation films B5 and B6 were bonded to the polarizer such that the cellulose ester film side was the polarizer side (the liquid crystal layer side was the opposite side of the polarizer).

  Step 1: A film (optical compensation film, cellulose ester film) immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to saponify the side to be bonded to the polarizer. Got.

  Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was lightly wiped off, and this was sandwiched and laminated between the optical compensation film treated in Step 1 and the cellulose ester film.

Step 4: pressure 20-30 N / cm ² to laminate obtained by laminating at Step 3, was stuck at about 2m / min conveyor speed.

  Step 5: The sample bonded in Step 4 in a dryer at 80 ° C. was dried for 2 minutes to produce polarizing plates PA4, PA6, PA7, and PB1-14.

<Preparation of polarizing plates PA1 to PA3, PA5>
An aqueous emulsion of a polyester ionomer type urethane resin (trade name “Hydran AP-20” manufactured by DIC Corporation, solid content concentration 30%, viscosity 30 mPa · sec) was added to 100 parts of a polyisocyanate compound (manufactured by DIC Corporation). A product name "Hydran Assist C1") is added so that 3 parts of the optical compensation films A1 to 3 and A5 in the MD direction (film transport direction, longitudinal direction) and the polarizer stretching direction coincide with each other. In addition, polarizing plates PA1 to PA3 and PA5 were produced.

<Production of liquid crystal cells C1 to C7>
An active matrix TFT and a pixel electrode are formed on a glass substrate with an ITO transparent electrode by an ordinary method to obtain an active matrix substrate. On the other hand, a color filter of three colors, a blue filter, a green filter, and a red filter, and a black matrix are formed on another glass substrate using a flexographic printing method. Further, a counter electrode made of an indium tin oxide film (ITO film) is formed thereon to form a color filter substrate. Next, a polyimide resin is applied to the counter electrode of the color filter substrate and the pixel electrode of the active matrix substrate using a spin coating method, respectively, and then a rubbing process is performed to form an alignment film. The color filter substrate and the active matrix substrate were bonded via a spacer so that the respective alignment films were opposed to each other, and liquid crystals having the wavelength dispersion described in Table 3 were injected between the substrates to produce a VA liquid crystal layer. Liquid crystal cells C1 to C7 having cell DSPs as shown in Table 3 were produced by appropriately changing the thicknesses of the three color filters of the blue filter, the green filter, and the red filter in the color filter substrate. The wavelength dispersion DSP (cell) of the liquid crystal cell was measured using an Axoscan manufactured by Axometrics.

<Production of liquid crystal display device>
The polarizing plates PA1 to 6 and PB1 to 14 prepared as described above are selected so as to have the combinations shown in Tables 4 to 7, and are attached via adhesive so as to be PA / color filter / liquid crystal / active matrix substrate / PB from the viewing side. Then, a backlight was arranged on the PB side to prepare liquid crystal display devices 1-0 to 1-8, 2-1 to 2-15, and 4-1. At that time, the polarizing plate is bonded so that the optical compensation film side (the side opposite to Konica Minolta Tack KC4UY) is on the liquid crystal cell side, and the absorption axes of PA and PB are orthogonal. Arranged.

  A liquid crystal display device 3-1 was produced in the same manner except that PB was placed on the viewing side and PA was placed on the backlight side.

  The following evaluation was performed using the liquid crystal display device produced as described above.

<< Evaluation of Liquid Crystal Display >>
<Evaluation of viewing angle>
The backlight of each liquid crystal display device was lit continuously for one week in an environment of 23 ° C. and 55% RH, and then the viewing angle was measured. For measurement, EZ-Contrast 160D manufactured by ELDIM was used to measure the luminance ratio A between black display and white display in directions of azimuth angles of 45 °, 135 °, 225 °, 315 °, and tilt angle of 70 °. The average value was adopted. When the measurement results were evaluated according to the following criteria, the results were as shown in Tables 4-6. In this evaluation standard, “Δ” means that it is practically within the allowable range, and “X” means that it is practically outside the allowable range.
A: 10000 <A ≦ 16000
○: 5000 <A ≦ 10000
Δ: 500 <A ≦ 5000
×: A ≦ 500
<Evaluation of front brightness>
The backlight of each liquid crystal display device was turned on in an environment of 23 ° C. and 55% RH, humidity was adjusted for 50 hours, and the luminance from the normal direction of the display screen during white display was measured. For measurement, CS-2000 manufactured by Konica Minolta Sensing Co., Ltd. was used. Note that when the white luminance exceeds 500 cd / m ² , the liquid crystal display device is excellent. In this evaluation standard, “◯” means that it is practically within the allowable range, and “×” means that it is practically outside the allowable range.
A: 500 <white luminance ○: 400 <white luminance ≦ 500
×: White luminance ≦ 400
<Evaluation of unevenness>
The manufactured liquid crystal display device was lit with a backlight in an environment of 23 ° C. and 10% RH and conditioned for 50 hours, and then the screen unevenness during black display was visually evaluated. In this evaluation standard, “◯” means that it is practically within the allowable range, and “×” means that it is practically outside the allowable range.
◎: 0 to 5 out of 20 felt unevenness ○: 5 to 10 out of 20 felt unevenness ×: 11 or more out of 20 felt unevenness <Measurement of orientation variation>
Alignment variation of the optical compensation film B was measured at each point using a birefringence measuring machine manufactured by Mizoji Optics Co., Ltd., and the alignment unevenness X was calculated from the following formula. did. Measurement range: 100 mm × 100 mm, measurement pitch: 1 mm.

<Variation evaluation of liquid crystal display devices>
The optical compensation film B1 was prepared, and a film having an orientation variation X having a measurement value described in Table 8 was selected to prepare polarizing plates PB1-2 to PB1-4. The polarizing plates PB and PA1 were fed out in a roll shape, and bonded to the liquid crystal cell C1 by a roll-to-panel manufacturing method to prepare 100 sets of liquid crystal display devices 5-1 to 5-3. Table 8 shows the results of evaluating these viewing angles by the above-described method and evaluating lot variations in viewing angles.

◎: 80 or more sets out of 100 sets have a viewing angle of 10,000 or more. ○: 50 to 79 sets in 100 sets have a viewing angle of 10,000 or more. X: 49 sets or less in 100 sets have a viewing angle of 10,000 or more <Overall evaluation>
The contents and evaluation results of the various liquid crystal display devices are summarized in Tables 4 to 8.

  From the above results, in the liquid crystal display devices 1-0 to 1-4 and 2-1 to 2-5 as examples of the present invention, the liquid crystal display devices 1-5 to 1-8 and 2-6 as comparative examples are shown. It can be seen that, unlike ˜2-16, a remarkable enlargement of the viewing angle is achieved and it is excellent. In addition, the range of an Example is shown with the graph in FIG.

  Further, by comparing the liquid crystal display devices 1-0 and 3-1, an optical compensation film that is a positive A plate layer (pA layer) is provided on the viewing side, and a negative C plate layer (nC layer) is provided on the backlight side. It was found that white luminance was improved by arranging an optical compensation film.

  Moreover, by comparing the liquid crystal display devices 1-0 and 4-1, it was found that display unevenness due to environmental fluctuations was reduced by reducing the thickness of the second optical compensation film.

  In addition, by comparing the liquid crystal display devices 5-1, 5-2 and 5-3 with the orientation variation of the second optical compensation film satisfying the formula (X), a lot of viewing angles generated when the roll-to-panel is bonded. It can be seen that the variation is reduced.

DESCRIPTION OF SYMBOLS 1, 5 Polarizer 2 1st optical compensation layer 3 Liquid crystal cell 4 2nd optical compensation layer 6, 8 Absorption axis 7 Slow axis 10 Polarizing roll 11 Bonding roll

Claims (5)

A liquid crystal display device in which a first optical compensation layer, a vertical alignment type liquid crystal cell, and a second optical compensation layer are disposed in this order, wherein the first optical compensation layer is a positive A plate layer, and the second optical compensation layer The compensation layer is a negative C plate layer, and the wavelength dispersion DSP (LC) of the liquid crystal, the wavelength dispersion DSP (CELL) of the liquid crystal cell, the wavelength dispersion DSP (I) of the first optical compensation layer, and the second optical compensation layer. A chromatic dispersion DSP (II) satisfying the following formulas (1) to (5):
Formula (1): 0.01 ≦ DSP (LC) −DSP (CELL) ≦ 0.10
Formula (2): DSP (CELL)> 1.0
Formula (3): 0.6 ≦ DSP (I) ≦ 0.8
Formula (4): DSP (II) ≦ −3.7x [DSP (LC) −DSP (CELL)] + 1.41
Formula (5): DSP (II) ≧ −1.1 × [DSP (LC) −DSP (CELL)] + 1.15
However,
DSP (CELL) is the ratio of the value at a wavelength of 450 nm to the value at a wavelength of 650 nm of the thickness direction retardation of the liquid crystal cell,
DSP (LC) is a ratio of a value at a wavelength of 450 nm to a value at a wavelength of 650 nm of Δn · d where Δn is the difference between the ordinary light refractive index and the extraordinary light refractive index when the liquid crystal is vertically aligned and the thickness is d. And
DSP (I) is a ratio of a value at a wavelength of 450 nm to a value at a wavelength of 650 nm of the in-plane retardation of the first optical compensation layer,
DSP (II) is a ratio of a value at a wavelength of 450 nm to a value at a wavelength of 650 nm of the thickness direction retardation of the second optical compensation layer. A first optical compensation layer disposed on the viewing side of the liquid crystal cell, a second optical compensation layer disposed on the backlight side, and an in-plane retardation Ro ₅₅₀ (I) at a wavelength of 550 nm of the first optical compensation layer; 2. The liquid crystal display device according to claim 1, wherein a thickness direction retardation Rt ₅₅₀ (II) at a wavelength of 550 nm of the second optical compensation layer satisfies the following formulas (R1) and (R2).
Formula (R1): 100 nm ≦ Ro ₅₅₀ (I) ≦ 200 nm
Formula (R2): 150 nm ≦ Rt ₅₅₀ (II) ≦ 250 nm The liquid crystal display device according to claim 1, wherein an alignment variation coefficient X of the second optical compensation layer satisfies the following formula (X).
Formula (X): 0.00000001 ≦ X ≦ 0.000001   4. The liquid crystal according to claim 1, wherein the first optical compensation layer contains a polycarbonate-based resin and the second optical compensation layer contains a cellulose-based resin. 5. Display device.   It is a manufacturing method of the liquid crystal display device which manufactures the liquid crystal display device according to any one of claims 1 to 4, and prepares a long roll-shaped polarizing plate having the first optical compensation layer, A manufacturing method of a liquid crystal display device, wherein the liquid crystal cell is bonded by a roll-to-panel manufacturing method.

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