JP2008026881A - Optical film, method for producing optical film, optical compensation film, polarizing plate and liquid crystal display device. - Google Patents

Abstract

An optical film having a high contrast ratio over a wide range and capable of suppressing color shift, a method for producing the optical film, an optical compensation film using the optical film, a polarizing plate, and a liquid crystal display device are provided.
The optical film of the present invention satisfies the following formulas (1) to (6).
(1) 150 ≦ Re (550) ≦ 400
(2) −100 ≦ Rth (550) ≦ 100
(3) 0.1 <Re (450) / Re (550) <0.95
(4) 1.03 <Re (650) / Re (550) <1.93
(5) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.95
(6) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90
(In formulas (1) to (6), Re (450), Re (550), and Re (650) are in-plane retardation values (unit: nm) measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively. Rth (450), Rth (550), and Rth (650) are retardation values (unit: nm) in the thickness direction measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
[Selection figure] None

Description

  The present invention relates to an optical film having a high contrast ratio over a wide range and capable of suppressing color shift, an optical film manufacturing method, an optical compensation film using the optical film, a polarizing plate, and a liquid crystal display device.

Liquid crystal display devices are widely used in monitors for personal computers and portable devices, and for television applications because of their various advantages, such as low voltage and low power consumption, enabling miniaturization and thinning. Various modes have been proposed for such a liquid crystal display device depending on the alignment state of the liquid crystal molecules in the liquid crystal cell. Conventionally, the liquid crystal display device is in an alignment state twisted by about 90 ° from the lower substrate to the upper substrate of the liquid crystal cell. The TN mode was mainstream.
In general, a liquid crystal display device includes a liquid crystal cell, an optical compensation sheet, and a polarizer. The optical compensation sheet is used for eliminating image coloring or expanding the viewing angle, and a stretched birefringent film or a film obtained by applying a liquid crystal to a transparent film is used. However, liquid crystal display devices for televisions that are expected to be viewed from various angles on a large screen have strict demands for viewing angle dependency, and from the demand for further improvement of viewing angle characteristics, IPS (In-Plane Switching) mode, OCB Liquid crystal display devices different from the TN mode, such as (Optically Compensatory Bend) mode and VA (Vertically Aligned) mode, have been studied. In particular, the IPS mode is attracting attention as a liquid crystal display device for TV because it has a high contrast and good viewing angle characteristics, and thus has a relatively high manufacturing yield.

  In the IPS mode, a slight light leakage in the diagonally oblique incidence direction during black display has become apparent as a cause of a decrease in display quality. As one means for improving the color tone and the viewing angle of black display, the arrangement of an optical compensation material having birefringence characteristics between the liquid crystal layer and the polarizing plate is also studied in the IPS mode. For example, based on the deviation from the orthogonality of the polarization axis crossing angle when the orthogonal polarizing plate is viewed obliquely by using a retardation film having an Nz of 0.4 to 0.6 and an in-plane retardation of 200 to 350 nm. An invention for suppressing light leakage is disclosed (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2004-4642

  However, these methods only reduce light leakage for a certain wavelength range (for example, green light near 550 nm), and light for other wavelength ranges (for example, blue light near 450 nm, red light near 650 nm). Leakage is not considered. For this reason, for example, when black is displayed and observed from an oblique direction, the so-called color shift problem of coloring blue or red has not been solved.

  The present invention has been made in view of such circumstances, and has an optical film having a high contrast ratio over a wide range and capable of suppressing color shift, an optical film manufacturing method, an optical film manufactured by the manufacturing method, An object of the present invention is to provide an optical compensation film, a polarizing plate, and a liquid crystal display device using them.

These objects were achieved by the following means [1] to [12].
[1]
An optical film characterized by satisfying the following formulas (1) to (6).
(1) 150 ≦ Re (550) ≦ 400
(2) −100 ≦ Rth (550) ≦ 100
(3) 0.1 <Re (450) / Re (550) <0.95
(4) 1.03 <Re (650) / Re (550) <1.93
(5) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.95
(6) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90
(In formulas (1) to (6), Re (450), Re (550), and Re (650) are in-plane retardation values (unit: nm) measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively. Rth (450), Rth (550), and Rth (650) are retardation values (unit: nm) in the thickness direction measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
[2]
The optical film according to [1], wherein the optical film contains cellulose acylate.
[3]
The optical film according to [1] or [2], wherein the optical film has a thickness of 10 to 300 μm.
[4]
A stretching process for stretching one of the longitudinal direction and the width direction of the film, and a shrinking process for contracting the other direction, and the film is compared with the film thickness before the stretching process and / or the shrinking process. A method for producing an optical film, wherein the thickness is increased.
[5]
The method for producing an optical film as described in [4], wherein the film thickness is increased by contraction by heating.
[6]
It includes a shrinking step of gripping and transporting a film by a tenter clip and shrinking by narrowing an interval in the transporting direction of the tenter clip, and a stretching step of stretching the film in a direction substantially perpendicular thereto. 4] or the method for producing an optical film according to [5].
[7]
The film includes a stretching step of gripping and transporting the film with a tenter clip and stretching the film by widening an interval in the transport direction of the tenter clip, and a step of contracting the film in a direction substantially perpendicular to the tenter clip [4 ] Or the manufacturing method of the optical film as described in [5].
[8]
An optical film produced by the production method according to any one of [4] to [7].
[9]
[1]-[3] or [8] An optical compensation film, wherein an optical anisotropic layer satisfying the following formula (7) is further formed on the optical film described in any one of [8].
(7) Re (550) = 0 to 200 (nm) and | Rth (550) | = 0 to 300 (nm)
[10]
A polarizing plate comprising at least one of the optical film according to any one of [1] to [3] or [8] and the optical compensation film according to [9].
[11]
It includes any one of the optical film according to any one of [1] to [3] or [8], the optical compensation film according to [9], and the polarizing plate according to [10]. A liquid crystal display device.
[12]
[11] The liquid crystal display device according to [11], wherein the liquid crystal cell is in an IPS mode.
[13]
A liquid crystal display device comprising: the polarizing plate according to [10]; a polarizing plate having an optical film satisfying the following formula (8) as a protective film for the polarizing plate; and an IPS cell.
(8) | Re (550) | = 0 to 10 (nm) and | Rth (550) | = 0 to 25 (nm)

  The present invention was completed based on the knowledge obtained as a result of intensive studies by the present inventors, and independently controls the wavelength dispersion of in-plane retardation and retardation in the thickness direction of an optical film. The optical optimum value is obtained, and the viewing angle compensation of the black state of the liquid crystal cell, in particular, the liquid crystal cell of the IPS mode is made possible at almost all wavelengths. As a result, in the liquid crystal display device of the present invention, light leakage in an oblique direction during black display is reduced, and the viewing angle contrast is remarkably improved. In addition, the liquid crystal display device of the present invention can suppress light leakage in an oblique direction during black display in almost all visible light wavelength regions. Has been greatly improved.

  In the present invention, “45 °”, “substantially parallel” or “substantially orthogonal” means that the angle is within a range of strictly less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °. Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction. Further, the “slow axis” means a direction in which the refractive index is maximized. The “visible light region” means 380 nm to 780 nm. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.

  In the present specification, unless otherwise specified, the `` polarizing plate '' is cut into a size to be incorporated into a long polarizing plate and a liquid crystal display device (in the present specification, `` cutting '' includes `` punching '' and `` It is also used to include both of the polarizing plates. In this specification, “polarizing film” and “polarizing plate” are distinguished from each other, and “polarizing plate” is a laminate having a transparent protective film for protecting the polarizing film on at least one side of the “polarizing film”. Shall mean.

  Next, with respect to the optical film of the present invention, optical characteristics, raw materials, production methods and the like will be described in more detail.

[Optical film]
The present invention relates to an optical film characterized by satisfying the following formulas (1) to (6).

(1) 150 ≦ Re (550) ≦ 400
(2) −100 ≦ Rth (550) ≦ 100
(3) 0.1 <Re (450) / Re (550) <0.95
(4) 1.03 <Re (650) / Re (550) <1.93
(5) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.95
(6) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90

  (In formulas (1) to (6), Re (450), Re (550), and Re (650) are in-plane retardation values (unit: nm) measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively. Rth (450), Rth (550), and Rth (650) are retardation values (unit: nm) in the thickness direction measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively.

  In the present invention, the film has optical characteristics in which the wavelength dispersion of the retardation is different between the normal direction and an oblique direction inclined with respect to the normal direction, for example, the polar angle direction of 60 degrees, and it is actively used for optical compensation. It is characterized by being used for. The scope of the present invention is not limited by the display mode of the liquid crystal layer, and can be used for a liquid crystal display device having a liquid crystal layer of any display mode such as VA mode, IPS mode, ECB mode, TN mode, and OCB mode. Can be preferably used particularly in the IPS mode.

  The optical film of the present invention can be effectively used as a retardation film having an optical compensation capability for a liquid crystal display device, and in particular, an increase in viewing angle contrast of a liquid crystal display device in IPS mode and a color shift depending on the viewing angle. Contributes to the reduction of The optical film of the present invention may be disposed between the observer-side polarizing plate and the liquid crystal cell, may be disposed between the back-side polarizing plate and the liquid crystal cell, or may be disposed on both. Good. For example, it can be incorporated into the liquid crystal display device as an independent member, or it can function as a retardation film having an optical compensation capability by adding the optical characteristics to a protective film for protecting the polarizing film. As a member of the plate, it can be incorporated in the liquid crystal display device.

  The above formulas (3) and (4) represent the wavelength dispersion of Re, and represent that Re increases as the wavelength increases (reverse dispersion). In addition, the above formulas (5) and (6) show the relationship between Re and Rth at each wavelength B (450 nm), G (550 nm), and R (650 nm). The shorter the wavelength, the larger the wavelength. In order to optically compensate the liquid crystal in the cell having a wavelength dispersibility such that the phase difference becomes smaller according to the above, the reverse dispersion of Re (Equations 3 and 4) is required, and this Re is in B, G, R This indicates that the degree of increase in Rth chromatic dispersion is smaller than the degree of increase. It has been found that by having the optical characteristics, it is possible to suppress a change in the color of the viewing angle on the liquid crystal display, and the effect of the present invention can be obtained.

As described above, the optical film of the present invention needs to satisfy the following formulas (1) and (2).
(1) 150 ≦ Re (550) ≦ 400
(2) −100 ≦ Rth (550) ≦ 100
Preferably,
(1-2) 200 ≦ Re (550) ≦ 350
(2-2) −70 ≦ Rth (550) ≦ 70
And more preferably
(1-3) 230 ≦ Re (550) ≦ 320
(2-3) -30 ≦ Rth (550) ≦ 30
It is.

Moreover, the optical film of this invention needs to satisfy | fill following formula (3)-(6).
(3) 0.1 <Re (450) / Re (550) <0.95
(4) 1.03 <Re (650) / Re (550) <1.93
(5) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.95
(6) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90
Meet the relationship.
Preferably,
(3-2) 0.2 <Re (450) / Re (550) <0.9,
(4-2) 1.05 <Re (650) / Re (550) <1.9,
(5-2) 0.5 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.9
(6-2) 1.1 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.8
It is.

  (In the above formulas (1) to (6), (1-2), (2-2), (1-3), (2-3), (3-2) to (6-2), Re ( 450), Re (550), and Re (650) are in-plane retardation values (unit: nm) measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively, and Rth (450), Rth (550), and Rth. (650) is the retardation value (unit: nm) in the thickness direction measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively.

(Retardation measurement)
In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured using KOBRA 21ADH or WR {manufactured by Oji Scientific Instruments Co., Ltd.) by making light having a wavelength of λ nm incident in the normal direction of the film.

When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) has an in-plane slow axis (determined by KOBRA 21ADH or WR) as a tilt axis (rotary axis) (in the absence of a slow axis, any direction in the film plane is the rotational axis) ), In a 10 ° step from the normal direction to 50 ° on one side with respect to the film normal direction, light of wavelength λ nm is incident from each inclined direction, and the retardation values at all six points are measured, KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.

  In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.

In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (when there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following formulas (1) and (2).
Formula (1):

  The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In Equation (1), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. To express.

  Formula (2):

  In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optic axis, Rth (λ) is calculated by the following method.

  Rth (λ) is an in-plane slow axis (determined by KOBRA 21ADH or WR) with an inclination axis (rotation axis) in 10 ° steps from −50 ° to + 50 ° with respect to the film normal direction. The retardation value at 11 points is measured by making light of wavelength λ nm incident from the inclined direction, and KOBRA is measured based on the measured retardation value, the assumed average refractive index, and the input film thickness value. 21ADH or WR is calculated.

  In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer.

Examples of the average refractive index values of main optical films are given below:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. From this calculated nx, ny, nz, Nz = (nx−nz) / (nx−ny) is further calculated.

  The thickness of the optical film is not particularly limited, but is 10 to 300 μm or less, preferably 40 to 250 μm, more preferably 60 to 250 μm, and particularly preferably 80 to 200 μm.

  The polymer material mainly constituting the optical film of the present invention that satisfies the above characteristics will be specifically described below.

[Material of optical film]
As the material for forming the optical film of the present invention, a polymer excellent in optical transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, and the like is preferable, and the wavelength dispersion of Re and the wavelength of Rth described above are preferable. Any material may be used as long as the dispersion satisfies the above formulas (3) to (6). Examples include polycarbonate polymers, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, acrylic polymers such as polymethyl methacrylate, and styrene polymers such as polystyrene and acrylonitrile / styrene copolymer (AS resin). Polyolefins such as polyethylene and polypropylene, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers , Polyether ether ketone polymers, polyphenylene sulfide polymers, vinylidene chloride polymers, vinyl alcohol polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or polymers mixed with the above polymers Take an example. The optical film of the present invention can also be formed as a cured layer of an ultraviolet-curable or thermosetting resin such as acrylic, urethane, acrylic urethane, epoxy, or silicone.

  Moreover, as a material for forming the optical film of the present invention, a thermoplastic norbornene resin can be preferably used. Examples of the thermoplastic norbornene-based resin include ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., and ARTON manufactured by JSR Corporation.

  Furthermore, as a material for forming the optical film of the present invention, a cellulose polymer (hereinafter referred to as cellulose acylate) represented by triacetyl cellulose, which has been conventionally used as a transparent protective film for polarizing plates, is preferably used. I can do it. Details of the cellulose acylate will be described below.

[Cellulose acylate raw material cotton]
Cellulose acylate raw material cellulose used in the optical film of the present invention includes cotton linter and wood pulp (hardwood pulp, conifer pulp), and any cellulose acylate obtained from any raw material cellulose can be used. May be used. Detailed descriptions of these raw material celluloses can be found in, for example, Plastic Materials Course (17) Fibrous Resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8) can be used, and the cellulose acylate film is not particularly limited.

[Substitution degree of cellulose acylate]
Next, the cellulose acylate produced from the above cellulose will be described. Cellulose acylate is obtained by acylating a hydroxyl group of cellulose, and the substituent can be any acetyl group having 2 carbon atoms in the acyl group to those having 22 carbon atoms. In cellulose acylate, the degree of substitution of cellulose with a hydroxyl group is not particularly limited, but the degree of substitution of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted with a hydroxyl group of cellulose is measured, and the degree of substitution is obtained by calculation. be able to. As a measuring method, it can carry out according to ASTM D-817-91.

  As described above, in the cellulose acylate, the substitution degree of the hydroxyl group of cellulose is not particularly limited, but the acyl substitution degree of the cellulose hydroxyl group is preferably 2.50 to 3.00. Furthermore, the substitution degree is more preferably 2.56 to 3.00, and particularly preferably 2.75 to 3.00.

  Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 3 to 22 carbon atoms is not particularly limited and may be an aliphatic group or an allyl group. A mixture of the above may also be used. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. These preferred acyl groups include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, Examples include oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl groups. Among these, acetyl, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are preferable, and acetyl, propionyl and butanoyl are more preferable.

  As a result of intensive studies by the inventor of the present invention, in the case where the acyl substituent substituted on the hydroxyl group of cellulose is at least two kinds substantially selected from an acetyl group, a propionyl group, and a butanoyl group, the total substitution thereof It was found that the optical anisotropy of the cellulose acylate film can be lowered when the degree is 2.50 to 3.00. The degree of acyl substitution is more preferably 2.60 to 3.00, still more preferably 2.65 to 3.00.

[Degree of polymerization of cellulose acylate]
The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average polymerization degree, and in cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. . When the degree of polymerization is too high, the viscosity of the cellulose acylate dope solution becomes high, and film production becomes difficult due to casting. If the degree of polymerization is too low, the strength of the produced film will decrease. The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). This is described in detail in JP-A-9-95538. In particular, when the transparent film of the present invention is produced using a cellulose acylate having an acyl substituent substantially consisting of only an acetyl group and having an average degree of polymerization of 180 to 550, good performance can be exhibited.

  Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. It is preferably 2.0 to 4.0, more preferably 2.0 to 3.5, and most preferably 2.3 to 3.3.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is in the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of cellulose acylate, its moisture content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less. Cellulose acylate. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In order to obtain the moisture content of the cellulose acylate in the present invention, it is necessary to dry, and the method is not particularly limited as long as the desired moisture content is obtained. These cellulose acylates of the present invention are described in detail on pages 7 to 12 in the raw material cotton and the synthesis method in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in.

  The cellulose acylate preferably has a substituent, a substitution degree, a polymerization degree, a molecular weight distribution, etc. within the above-mentioned ranges, and a single or two or more different types of cellulose acylates can be mixed and used.

[Additives to optical films]
In the optical film solution of the present invention, various additives according to the use in each preparation step (for example, retardation developing agent, retardation reducing agent, wavelength dispersion adjusting agent, ultraviolet ray preventing agent, plasticizer, deterioration preventing agent, Fine particles, optical property modifiers, etc.) can be added and these are described below. Further, the addition may be performed at any time in the dope preparation process, but may be performed by adding an additive to the final preparation process of the dope preparation process.

  In the optical film of the present invention, a retardation developer composed of a discotic compound or a rod-shaped compound can be preferably used as a compound that increases retardation.

(Retardation expression agent)
The optical film of the present invention may contain one or more retardation enhancers composed of a disk-like compound or a rod-like compound in order to increase the short wavelength side of the Rth wavelength dispersion and to perform forward dispersion. With the retardation enhancer, the in-plane retardation Re and the retardation Rth in the film thickness direction are brought close to desired values, and the wavelength dispersion characteristics satisfying the expressions (3) to (6) at Re and Rth at each wavelength are good. It becomes. In particular, in the present invention, since the wavelength dispersion of Re can be brought into a desired range by the above-described stretching operation of the optical film, the retardation developing agent not only helps the Re expression, but mainly the wavelength of Rth. It helps to bring the variance closer to the desired range of values. To bring the Rth wavelength dispersion closer to the desired range, the Rth in the short wave region is relatively higher than that on the long wave side because the discotic compound or rod-like compound having absorption in the short wave region is oriented substantially horizontally in the film. Can be considered.

  In order to raise the Rth of the upper shortwave region relative to the longer wave side, both a discotic compound and a rod-like compound can be preferably used. From the viewpoint of the ability to orient in a film substantially horizontally, the discotic compound is used. More preferably, it is used.

The retardation developing agent means that Re and Rth are added by adding 1 part by mass with respect to 100 parts by mass of a polymer component (hereinafter sometimes referred to as “polymer component”) such as cellulose acylate contained in the optical film of the present invention. Is increased by 0.11 or more per micron film thickness. More preferably, the retardation is increased by 0.2 or more per micron of film thickness, more preferably 0.3 or more per micron of film thickness.
Examples of the retardation enhancer that can be used in the present invention include those composed of rod-like or discotic compounds. As the disk-like or rod-like compound, a compound having at least two aromatic rings can be used.
The discotic retardation enhancer is preferably used in the range of 0.05 to 30 parts by mass, more preferably in the range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the polymer component. Preferably, it is used in the range of 0.2 to 15 parts by weight, more preferably in the range of 0.5 to 10 parts by weight.
The addition amount of the retardation enhancer composed of the rod-shaped compound is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component.
Since the discotic compound is superior to the rod-like compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required.
Two or more retardation developing agents may be used in combination.
It is preferable that the retardation developer composed of a rod-like or discotic compound has substantially no absorption in the visible region.

(Discotic compound)
Specific examples of the retardation developing agent comprising a discotic compound preferably used in the present invention are shown below, but are not limited thereto.
In the present invention, a compound represented by the following general formula (1) can be preferably used as a retardation developer comprising a discotic compound. The compound represented by the general formula (1) is preferable because the molecular structure has rotational symmetry with the triazine ring as the center, and thus has high retardation and can be produced at low cost.
General formula (1)

In the above general formula (1):
Each R ¹ independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho position, meta position and para position.
X ¹ each independently represents a single bond or —NR ³ —. Here, each R ³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ¹ is preferably phenyl or naphthyl, and particularly preferably phenyl.
The aromatic ring represented by R ¹ may have at least one substituent at any substitution position. Examples of the substituent include a halogen atom, hydroxyl, cyano, nitro, carboxyl, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, alkenyloxycarbonyl group , Aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide group, alkylthio group , An alkenylthio group, an arylthio group, and an acyl group.

The heterocyclic group represented by R ¹ preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.
When X ¹ is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. In addition, the heterocyclic group may have a hetero atom other than the nitrogen atom (eg, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below.

In general formula (1), X ¹ represents a single bond or —NR ³ —. R ³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, alkenyl group, aryl group or heterocyclic group.
The alkyl group represented by R ³ may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, further preferably 1-10, still more preferably 1-8, and 1-6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy, ethoxy) and an acyloxy group (for example, acryloyloxy, methacryloyloxy).

The alkenyl group represented by R ³ may be a cyclic alkenyl group or a chain alkenyl group, but is preferably a chain alkenyl group and is more preferably a linear alkenyl group than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.
The aromatic ring group and heterocyclic group represented by R ³ are the same as the aromatic ring and heterocyclic ring represented by R ¹ , and the preferred range is also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of R ¹ .

The molecular weight of the retardation developer composed of the discotic compound represented by the general formula (1) is preferably 300 to 800.
In addition, a UV absorber may be used in combination with a retardation developer composed of a discotic compound represented by the general formula (1). The amount of the UV absorber used is preferably 10 parts by mass or less, and more preferably 3 parts by mass or less, with respect to 100 parts by mass of the retardation developer composed of the discotic compound represented by the general formula (1).

  Specific examples of the retardation enhancer comprising the discotic compound represented by the general formula (1) used in the present invention are shown below. Several R shown in each example means the same group. The definition of R is shown after the formula together with the specific example number.

(1) phenyl (2) 3-ethoxycarbonylphenyl (3) 3-butoxyphenyl (4) m-biphenylyl (5) 3-phenylthiophenyl (6) 3-chlorophenyl (7) 3-benzoylphenyl (8) 3 -Acetoxyphenyl (9) 3-Benzoyloxyphenyl (10) 3-phenoxycarbonylphenyl (11) 3-methoxyphenyl (12) 3-anilinophenyl (13) 3-isobutyrylaminophenyl (14) 3-phenoxy Carbonylaminophenyl (15) 3- (3-ethylureido) phenyl (16) 3- (3,3-diethylureido) phenyl (17) 3-methylphenyl (18) 3-phenoxyphenyl (19) 3-hydroxyphenyl

(20) 4-ethoxycarbonylphenyl (21) 4-butoxyphenyl (22) p-biphenylyl (23) 4-phenylthiophenyl (24) 4-chlorophenyl (25) 4-benzoylphenyl (26) 4-acetoxyphenyl ( 27) 4-benzoyloxyphenyl (28) 4-phenoxycarbonylphenyl (29) 4-methoxyphenyl (30) 4-anilinophenyl (31) 4-isobutyrylaminophenyl (32) 4-phenoxycarbonylaminophenyl ( 33) 4- (3-ethylureido) phenyl (34) 4- (3,3-diethylureido) phenyl (35) 4-methylphenyl (36) 4-phenoxyphenyl (37) 4-hydroxyphenyl

(38) 3,4-diethoxycarbonylphenyl (39) 3,4-dibutoxyphenyl (40) 3,4-diphenylphenyl (41) 3,4-diphenylthiophenyl (42) 3,4-dichlorophenyl (43 ) 3,4-dibenzoylphenyl (44) 3,4-diacetoxyphenyl (45) 3,4-dibenzoyloxyphenyl (46) 3,4-diphenoxycarbonylphenyl (47) 3,4-dimethoxyphenyl ( 48) 3,4-dianilinophenyl (49) 3,4-dimethylphenyl (50) 3,4-diphenoxyphenyl (51) 3,4-dihydroxyphenyl (52) 2-naphthyl

(53) 3,4,5-triethoxycarbonylphenyl (54) 3,4,5-tributoxyphenyl (55) 3,4,5-triphenylphenyl (56) 3,4,5-triphenylthiophenyl (57) 3,4,5-trichlorophenyl (58) 3,4,5-tribenzoylphenyl (59) 3,4,5-triacetoxyphenyl (60) 3,4,5-tribenzoyloxyphenyl (61 ) 3,4,5-triphenoxycarbonylphenyl (62) 3,4,5-trimethoxyphenyl (63) 3,4,5-trianilinophenyl (64) 3,4,5-trimethylphenyl (65) 3,4,5-triphenoxyphenyl (66) 3,4,5-trihydroxyphenyl

(67) phenyl (68) 3-ethoxycarbonylphenyl (69) 3-butoxyphenyl (70) m-biphenylyl (71) 3-phenylthiophenyl (72) 3-chlorophenyl (73) 3-benzoylphenyl (74) 3 -Acetoxyphenyl (75) 3-benzoyloxyphenyl (76) 3-phenoxycarbonylphenyl (77) 3-methoxyphenyl (78) 3-anilinophenyl (79) 3-isobutyrylaminophenyl (80) 3-phenoxy Carbonylaminophenyl (81) 3- (3-ethylureido) phenyl (82) 3- (3,3-diethylureido) phenyl (83) 3-methylphenyl (84) 3-phenoxyphenyl (85) 3-hydroxyphenyl

(86) 4-ethoxycarbonylphenyl (87) 4-butoxyphenyl (88) p-biphenylyl (89) 4-phenylthiophenyl (90) 4-chlorophenyl (91) 4-benzoylphenyl (92) 4-acetoxyphenyl ( 93) 4-Benzoyloxyphenyl (94) 4-phenoxycarbonylphenyl (95) 4-methoxyphenyl (96) 4-anilinophenyl (97) 4-isobutyrylaminophenyl (98) 4-phenoxycarbonylaminophenyl ( 99) 4- (3-Ethylureido) phenyl (100) 4- (3,3-diethylureido) phenyl (101) 4-methylphenyl (102) 4-phenoxyphenyl (103) 4-hydroxyphenyl

(104) 3,4-diethoxycarbonylphenyl (105) 3,4-dibutoxyphenyl (106) 3,4-diphenylphenyl (107) 3,4-diphenylthiophenyl (108) 3,4-dichlorophenyl (109) ) 3,4-dibenzoylphenyl (110) 3,4-diacetoxyphenyl (111) 3,4-dibenzoyloxyphenyl (112) 3,4-diphenoxycarbonylphenyl (113) 3,4-dimethoxyphenyl ( 114) 3,4-dianilinophenyl (115) 3,4-dimethylphenyl (116) 3,4-diphenoxyphenyl (117) 3,4-dihydroxyphenyl (118) 2-naphthyl

(119) 3,4,5-triethoxycarbonylphenyl (120) 3,4,5-tributoxyphenyl (121) 3,4,5-triphenylphenyl (122) 3,4,5-triphenylthiophenyl (123) 3,4,5-trichlorophenyl (124) 3,4,5-tribenzoylphenyl (125) 3,4,5-triacetoxyphenyl (126) 3,4,5-tribenzoyloxyphenyl (127 ) 3,4,5-triphenoxycarbonylphenyl (128) 3,4,5-trimethoxyphenyl (129) 3,4,5-trianilinophenyl (130) 3,4,5-trimethylphenyl (131) 3,4,5-triphenoxyphenyl (132) 3,4,5-trihydroxyphenyl

(133) phenyl (134) 4-butylphenyl (135) 4- (2-methoxy-2-ethoxyethyl) phenyl (136) 4- (5-nonenyl) phenyl (137) p-biphenylyl (138) 4-ethoxy Carbonylphenyl (139) 4-butoxyphenyl (140) 4-methylphenyl (141) 4-chlorophenyl (142) 4-phenylthiophenyl (143) 4-benzoylphenyl (144) 4-acetoxyphenyl (145) 4-benzoyl Oxyphenyl (146) 4-phenoxycarbonylphenyl (147) 4-methoxyphenyl (148) 4-anilinophenyl (149) 4-isobutyrylaminophenyl (150) 4-phenoxycarbonylaminophenyl (151) 4- ( 3-ethylureido Phenyl (152) 4- (3,3-diethyl-ureido) phenyl (153) 4-phenoxyphenyl (154) 4-hydroxyphenyl

(155) 3-butylphenyl (156) 3- (2-methoxy-2-ethoxyethyl) phenyl (157) 3- (5-nonenyl) phenyl (158) m-biphenylyl (159) 3-ethoxycarbonylphenyl (160 ) 3-butoxyphenyl (161) 3-methylphenyl (162) 3-chlorophenyl (163) 3-phenylthiophenyl (164) 3-benzoylphenyl (165) 3-acetoxyphenyl (166) 3-benzoyloxyphenyl (167) ) 3-phenoxycarbonylphenyl (168) 3-methoxyphenyl (169) 3-anilinophenyl (170) 3-isobutyrylaminophenyl (171) 3-phenoxycarbonylaminophenyl (172) 3- (3-ethylureido ) Phenyl (173 3- (3,3-diethyl-ureido) phenyl (174) 3-phenoxyphenyl 175 3-hydroxyphenyl

(176) 2-butylphenyl (177) 2- (2-methoxy-2-ethoxyethyl) phenyl (178) 2- (5-nonenyl) phenyl (179) o-biphenylyl (180) 2-ethoxycarbonylphenyl (181) ) 2-butoxyphenyl (182) 2-methylphenyl (183) 2-chlorophenyl (184) 2-phenylthiophenyl (185) 2-benzoylphenyl (186) 2-acetoxyphenyl (187) 2-benzoyloxyphenyl (188) ) 2-phenoxycarbonylphenyl (189) 2-methoxyphenyl (190) 2-anilinophenyl (191) 2-isobutyrylaminophenyl (192) 2-phenoxycarbonylaminophenyl (193) 2- (3-ethylureido ) Phenyl (194 2- (3,3-diethyl-ureido) phenyl (195) 2-phenoxyphenyl (196) 2-hydroxyphenyl

(197) 3,4-dibutylphenyl (198) 3,4-di (2-methoxy-2-ethoxyethyl) phenyl (199) 3,4-diphenylphenyl (200) 3,4-diethoxycarbonylphenyl (201 ) 3,4-didodecyloxyphenyl (202) 3,4-dimethylphenyl (203) 3,4-dichlorophenyl (204) 3,4-dibenzoylphenyl (205) 3,4-diacetoxyphenyl (206) 3 , 4-dimethoxyphenyl (207) 3,4-di-N-methylaminophenyl (208) 3,4-diisobutyrylaminophenyl (209) 3,4-diphenoxyphenyl (210) 3,4-dihydroxyphenyl

(211) 3,5-dibutylphenyl (212) 3,5-di (2-methoxy-2-ethoxyethyl) phenyl (213) 3,5-diphenylphenyl (21
4) 3,5-diethoxycarbonylphenyl (215) 3,5-didodecyloxyphenyl (216) 3,5-dimethylphenyl (217) 3,5-dichlorophenyl (218) 3,5-dibenzoylphenyl (219) ) 3,5-diacetoxyphenyl (220) 3,5-dimethoxyphenyl (221) 3,5-di-N-methylaminophenyl (222) 3,5-diisobutyrylaminophenyl (223) 3,5- Diphenoxyphenyl (224) 3,5-dihydroxyphenyl

(225) 2,4-dibutylphenyl (226) 2,4-di (2-methoxy-2-ethoxyethyl) phenyl (227) 2,4-diphenylphenyl (228) 2,4-diethoxycarbonylphenyl (229) ) 2,4-didodecyloxyphenyl (230) 2,4-dimethylphenyl (231) 2,4-dichlorophenyl (232) 2,4-dibenzoylphenyl (233) 2,4-diacetoxyphenyl (234) 2 , 4-dimethoxyphenyl (235) 2,4-di-N-methylaminophenyl (236) 2,4-diisobutyrylaminophenyl (237) 2,4-diphenoxyphenyl (238) 2,4-dihydroxyphenyl

(239) 2,3-dibutylphenyl (240) 2,3-di (2-methoxy-2-ethoxyethyl) phenyl (241) 2,3-diphenylphenyl (242) 2,3-diethoxycarbonylphenyl (243 ) 2,3-didodecyloxyphenyl (244) 2,3-dimethylphenyl (245) 2,3-dichlorophenyl (246) 2,3-dibenzoylphenyl (247) 2,3-diacetoxyphenyl (248) 2 , 3-dimethoxyphenyl (249) 2,3-di-N-methylaminophenyl (250) 2,3-diisobutyrylaminophenyl (251) 2,3-diphenoxyphenyl (252) 2,3-dihydroxyphenyl

(253) 2,6-dibutylphenyl (254) 2,6-di (2-methoxy-2-ethoxyethyl) phenyl (255) 2,6-diphenylphenyl (256) 2,6-diethoxycarbonylphenyl (257 ) 2,6-didodecyloxyphenyl (258) 2,6-dimethylphenyl (259) 2,6-dichlorophenyl (260) 2,6-dibenzoylphenyl (261) 2,6-diacetoxyphenyl (262) 2 , 6-dimethoxyphenyl (263) 2,6-di-N-methylaminophenyl (264) 2,6-diisobutyrylaminophenyl (265) 2,6-diphenoxyphenyl (266) 2,6-dihydroxyphenyl

(267) 3,4,5-tributylphenyl (268) 3,4,5-tri (2-methoxy-2-ethoxyethyl) phenyl (269) 3,4,5-triphenylphenyl (270) 3,4 , 5-triethoxycarbonylphenyl (271) 3,4,5-tridodecyloxyphenyl (272) 3,4,5-trimethylphenyl (273) 3,4,5-trichlorophenyl (274) 3,4,5 -Tribenzoylphenyl (275) 3,4,5-triacetoxyphenyl (276) 3,4,5-trimethoxyphenyl (277) 3,4,5-tri-N-methylaminophenyl (278) 3,4 , 5-Triisobutyrylaminophenyl (279) 3,4,5-triphenoxyphenyl (280) 3,4,5-trihydroxyphenyl

(281) 2,4,6-tributylphenyl (282) 2,4,6-tri (2-methoxy-2-ethoxyethyl) phenyl (283) 2,4,6-triphenylphenyl (284) 2,4 , 6-triethoxycarbonylphenyl (285) 2,4,6-tridodecyloxyphenyl (286) 2,4,6-trimethylphenyl (287) 2,4,6-trichlorophenyl (288) 2,4,6 -Tribenzoylphenyl (289) 2,4,6-triacetoxyphenyl (290) 2,4,6-trimethoxyphenyl (291) 2,4,6-tri-N-methylaminophenyl (292) 2,4 , 6-Triisobutyrylaminophenyl (293) 2,4,6-triphenoxyphenyl (294) 2,4,6-trihydroxyphenyl

(295) pentafluorophenyl (296) pentachlorophenyl (297) pentamethoxyphenyl (298) 6-N-methylsulfamoyl-8-methoxy-2-naphthyl (299) 5-N-methylsulfamoyl-2- Naphthyl (300) 6-N-phenylsulfamoyl-2-naphthyl (301) 5-Ethoxy-7-N-methylsulfamoyl-2-naphthyl (302) 3-methoxy-2-naphthyl (303) 1- Ethoxy-2-naphthyl (304) 6-N-phenylsulfamoyl-8-methoxy-2-naphthyl (305) 5-methoxy-7-N-phenylsulfamoyl-2-naphthyl (306) 1- (4 -Methylphenyl) -2-naphthyl (307) 6,8-di-N-methylsulfamoyl-2-naphthyl (308 ) 6-N-2-acetoxyethylsulfamoyl-8-methoxy-2-naphthyl (309) 5-acetoxy-7-N-phenylsulfamoyl-2-naphthyl (310) 3-benzoyloxy-2-naphthyl

(311) 5-acetylamino-1-naphthyl (312) 2-methoxy-1-naphthyl (313) 4-phenoxy-1-naphthyl (314) 5-N-methylsulfamoyl-1-naphthyl (315) 3 -N-methylcarbamoyl-4-hydroxy-1-naphthyl (316) 5-methoxy-6-N-ethylsulfamoyl-1-naphthyl (317) 7-tetradecyloxy-1-naphthyl (318) 4- ( 4-methylphenoxy) -1-naphthyl (319) 6-N-methylsulfamoyl-1-naphthyl (320) 3-N, N-dimethylcarbamoyl-4-methoxy-1-naphthyl (321) 5-methoxy- 6-N-benzylsulfamoyl-1-naphthyl (322) 3,6-di-N-phenylsulfamoyl-1-naphthyl

(323) methyl (324) ethyl (325) butyl (326) octyl (327) dodecyl (328) 2-butoxy-2-ethoxyethyl (329) benzyl (330) 4-methoxybenzyl

(331) Methyl (332) Phenyl (333) Butyl

  The retardation developing agent represented by the general formula (1) is used in an amount of 0.01 to 20 parts by mass, preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the polymer raw material. By using a retardation developer within this range, the retardation of the film can be appropriately controlled. When the amount is less than 0.01 parts by mass, the retardation is not increased and the retardation cannot be controlled. When the amount exceeds 20 parts by mass, the retardation developer is not compatible with the polymer raw material and crystallizes in the film.

(Bar compound)
In the present invention, in addition to the aforementioned discotic compound, a rod-shaped compound having a linear molecular structure can also be preferably used. The linear molecular structure means that the molecular structure of the rod-shaped compound is linear in the thermodynamically most stable structure.

  In the present invention, a rod-shaped compound having an absorption maximum on the shorter wavelength side than 250 nm is used as an advantageous compound for forward dispersion of Rth. On the other hand, in-plane retardation Re is advantageously expressed from the properties of the rod-shaped compound. It is also preferable to use it as a retardation developer. From the viewpoint of the function of the retardation enhancer, the rod-like compound preferably has at least one aromatic ring, and more preferably has at least two aromatic rings.

  The rod-like compound preferably has a linear molecular structure. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation can be performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited) to determine the molecular structure that minimizes the heat of formation of the compound. The molecular structure being linear means that the angle of the molecular structure is 140 degrees or more in the thermodynamically most stable structure obtained by calculation as described above.

  As the rod-like compound, a compound represented by the following formula (I) is preferable.

(I) Ar ¹ -L ¹ -Ar ²

In formula (I), Ar ¹ and Ar ² are each independently an aromatic group. In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group. An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. 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 a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more 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 Rings, pyridazine rings, pyrimidine rings, pyrazine rings, and 1,3,5-triazine rings are included. As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include halogen atom (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, alkylamino group (eg, methylamino, ethylamino) , Butylamino, dimethylamino), nitro, sulfo, carbamoyl, alkylcarbamoyl groups (eg, N-methylcarbamoyl, N-ethylcarbamoyl, N, N-dimethylcarbamoyl), sulfamoyl, alkylsulfamoyl groups (eg, N- Methylsulfamoyl, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), ureido, alkylureido groups (eg, N-methylureido, N, N-dimethylureido, N, N, N′-trimethyl) Ureido), alkyl groups (eg, methyl, ethyl, propyl, butyl, pentyl, Heptyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, cyclopentyl), alkenyl groups (eg, vinyl, allyl, hexenyl), alkynyl groups (eg, ethynyl, butynyl), acyl groups (eg, formyl, acetyl, Butyryl, hexanoyl, lauryl), acyloxy groups (eg, acetoxy, butyryloxy, hexanoyloxy, lauryloxy), alkoxy groups (eg, methoxy, ethoxy, propoxy, butoxy, pentyloxy, heptyloxy, octyloxy), aryloxy groups (Eg, phenoxy), alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, heptyloxycarbonyl), aryloxycarbo Group (eg, phenoxycarbonyl), alkoxycarbonylamino group (eg, butoxycarbonylamino, hexyloxycarbonylamino), alkylthio group (eg, methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio, octylthio), arylthio group (eg, , Phenylthio), alkylsulfonyl groups (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl), amide groups (eg, acetamido, butyramide, hexylamide, laurylamide) and non- Aromatic heterocyclic groups (eg, morpholyl, pyrazinyl) are included.

  Substituents of substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms, cyano, carboxyl, hydroxyl, amino, alkyl-substituted amino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthios. And groups and alkyl groups are preferred. The alkyl part and alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl, carboxyl, cyano, amino, alkylamino group, nitro, sulfo, carbamoyl, alkylcarbamoyl group, sulfamoyl, alkylsulfamoyl group, ureido, alkylureido Group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, alkylsulfonyl group, amide group and non-aromatic An aromatic heterocyclic group is included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, hydroxyl, amino, alkylamino group, acyl group, acyloxy group, acylamino group, alkoxycarbonyl group and alkoxy group are preferable.

In the formula (I), L ¹ is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and combinations thereof. The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group. The alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, still more preferably 1 to 10 carbon atoms, still more preferably 1 to 8 carbon atoms. 6 is most preferred.

  The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure. The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4. Most preferred is 2 (vinylene or ethynylene).

The example of the bivalent coupling group which consists of a combination is shown.
L-1: —O—CO-alkylene group —CO—O—
L-2: -CO-O-alkylene group -O-CO-
L-3: —O—CO—alkenylene group —CO—O—
L-4: -CO-O-alkenylene group -O-CO-
L-5: -O-CO-alkynylene group -CO-O-
L-6: -CO-O-alkynylene group -O-CO-

In the molecular structure of the formula (I), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more. As the rod-like compound, a compound represented by the following formula (II) is more preferable.

(II) Ar ¹ -L ² -XL ³ -Ar ²

In the formula (II), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those for Ar ¹ and Ar ^{2 in} the formula (I).

In the formula (II), L ² and L ³ are each independently a divalent linking group selected from the group consisting of an alkylene group, —O—, —CO—, and combinations thereof. The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure. The number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, still more preferably 1 to 4, and 1 or Most preferred is 2 (methylene or ethylene). L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the formula (II), X is 1,4-cyclohexylene, vinylene or ethynylene. Specific examples of the compound represented by formula (I) are shown below.

  Specific examples (1) to (34), (41), and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41), and (42) have a symmetrical meso type molecular structure, there are no optical isomers (optical activity), and geometric isomers (trans Type and cis type). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

  As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type. Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate. In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

  Other preferred compounds are shown below.

  Two or more rod-shaped compounds whose maximum absorption wavelength (λmax) is shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination. The rod-like compound can be synthesized with reference to methods described in literature. References include Mol. Cryst. Liq. Cryst., 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 Page (1989), J. Am. Chem. Soc., 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970), J. Org Chem., 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

(Spectrum measurement of a specific example)
The ultraviolet-visible region (UV-vis) spectrum of the retardation control agent (10-trans) was measured. The retardation control agent (10-trans) was dissolved in tetrahydrofuran (without stabilizer (BHT)) and adjusted to a concentration of 10 ⁻⁵ mol / dm ³ . When the solution prepared in this way was measured with a measuring instrument (manufactured by Hitachi, Ltd.), the wavelength (λmax) giving an absorption maximum was 220 nm, and the extinction coefficient (ε) at that time was 15000. Similarly, in the retardation control agent (29-trans), the wavelength (λmax) giving the absorption maximum was 240 nm, and the extinction coefficient (ε) at that time was 20000. Similarly, in the retardation control agent (41-trans), the wavelength (λmax) giving the absorption maximum was 230 nm, and the extinction coefficient (ε) at that time was 16000.

  Two or more rod-shaped compounds whose maximum absorption wavelength (λmax) is shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.

(Other retardation agents)
In addition to the above, the in-plane retardation Re and the retardation Rth in the film thickness direction are brought close to desired values, and the Re and Rth at each wavelength have chromatic dispersion characteristics satisfying the expressions (3) to (6). As long as it is possible, it can be added to the optical film of the present invention without limitation.

[Other additives]
(Fine particles)
Next, the fine particles preferably used in the present invention will be described.
In the present invention, the fine particles are also referred to as a matting agent. In order to improve the slipperiness of the film surface, it is effective to give unevenness to the film surface, and by adding fine particles of organic and / or inorganic substances to increase the roughness of the film surface, so-called matting By doing so, a method of reducing blocking between films is known. Further, in the present invention, it may be present in the optical film. For example, fine particles may be present on at least one surface of the optical film. Due to the presence of the fine particles, the adhesion between the polarizer and the optical film during polarizing plate processing is significantly improved. From these viewpoints, it is preferable to add and use fine particles in the present invention.

  When using an optical film as a transparent optical film for polarizing plate protective film, the average particle size and content can be reduced because the haze can be suppressed and the transparency can be maintained so as to suppress matting for a rough surface. The following ranges are suitable.

  In the case of inorganic fine particles, the matting agent used in the present invention is preferably fine particles having an average particle diameter in the film of 0.05 μm to 3.0 μm, more preferably 0.05 μm to 1.0 μm, still more preferably 0.08 μm. ˜0.50 μm, particularly preferably 0.10 μm to 0.30 μm. As the average particle diameter of the inorganic fine particles in the film, a desired average particle diameter in the film can be selected by the average primary particle diameter of the fine particles and the dispersion treatment described later. When the matting agent used in the present invention is inorganic fine particles, the average primary particle size of the fine particles is preferably 0.005 μm to 0.5 μm, and more preferably 0.01 μm to 0.2 μm.

  The polymer fine particles are preferable because a desired refractive index can be obtained by selecting a polymer species. Furthermore, since the polymer fine particles have high compatibility with cellulose acylate and can suppress haze, refraction and scattering when a film is formed using the polymer fine particles, when using the polymer fine particles as a matting agent, It is preferable to select a grade having a larger size than using inorganic fine particles as a matting agent.

  In the case of a polymer, the matting agent used in the present invention is preferably fine particles having an average particle size of 0.1 μm to 3.0 μm, more preferably 0.15 μm to 2.0 μm, and further preferably 0.2 μm to 1.0 μm. is there.

  The average particle size of the matting agent described in the present invention is the average size in the film (including the matting agent present on the film surface), regardless of whether the matting agent is aggregated or non-aggregated. This particle size is an average of equivalent circle diameters of 100 particles obtained by SEM observation and / or TEM observation of the film surface and the slice. The equivalent circle diameter can be obtained by converting the projected area of the particles obtained by photographing into the diameter of a circle having the same area.

  The average particle size of the matting agent means the average size (average secondary particle size) of the aggregate if it is agglomerated particles, and the dispersion formulation described later if manufactured by the solution casting film forming method. Can be controlled as the particle size in the dispersion. In the case of non-aggregating particles, it means an average value obtained by measuring the size of one particle.

  The content is, for example, 0.03 to 1.0% by mass in the solid content of the optical film regardless of the type of spherical, indeterminate, inorganic fine particles, and polymer matting agent, and more preferably 0.05 to 1.0% by mass. It is 0.6 mass%, More preferably, it is 0.08-0.4 mass%.

  The preferable haze range of the optical film containing the matting agent in the present invention is 4.0% or less, more preferably 2.0% or less, and particularly preferably 1.0% or less. In order to reduce the haze, the added fine particles are sufficiently dispersed to reduce the number of aggregated particles, or the fine particles are used only in the skin layer in order to reduce the addition amount. The haze can be measured using a 1001DP type haze meter manufactured by Nippon Denshoku Industries Co., Ltd.

  The dispersion method is not particularly limited, and a conventional method can be used. For example, examples of the media disperser include an attritor, a ball mill, a sand mill, and a dyno mill. Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. It is preferable to use the above-described dispersing device for dispersion, but it is not necessary to use it.

  The method for incorporating the matting agent into the film is not particularly limited, and examples include a method in which a solution containing the polymer and the matting agent is cast to form a film, and a method in which the matting agent dispersion is applied to the formed film. . From the viewpoint that the distribution of the matting agent on the film surface can be easily controlled, a method of applying a matting agent dispersion to the formed film is preferable. In terms of cost, a solution containing the polymer and the matting agent is cast to form a film. The method is preferred. A method of casting a film in the multi-layer casting method described later can also be preferably used as a film forming method capable of controlling the distribution of the matting agent on the film surface.

  In the case of casting a solution containing a polymer and a matting agent, the matting agent may be dispersed when preparing the polymer solution, or the matting agent dispersion may be added immediately before casting the polymer solution. You may mix. In order to disperse the matting agent in the polymer solution, a small amount of a surfactant or polymer may be added as a dispersion aid. In addition to the above method, a matting agent layer may be applied after film formation. In this case, it is preferable to use a binder for forming the matting agent layer. The binder for the layer containing the matting agent of the present invention is not particularly limited, and may be a lipophilic binder or a hydrophilic binder. As the lipophilic binder, known thermoplastic resins, thermosetting resins, radiation curable resins, reactive resins, and mixtures thereof can be used. The Tg of the resin is preferably 80 ° C to 400 ° C, more preferably 120 ° C to 350 ° C. The weight average molecular weight of the resin is preferably 10,000 to 1,000,000, more preferably 10,000 to 500,000.

  Examples of the thermoplastic resin include vinyl chloride / vinyl acetate copolymers, vinyl chloride, copolymers of vinyl acetate and vinyl alcohol, maleic acid and / or acrylic acid, vinyl chloride / vinylidene chloride copolymers, vinyl chloride / Acrylonitrile copolymer, vinyl copolymer such as ethylene / vinyl acetate copolymer, cellulose derivatives such as nitrocellulose, cellulose acetate propionate, cellulose acetate butyrate resin, cyclic polyolefin resin, acrylic resin, polyvinyl acetal resin, Polyvinyl butyral resin, polyester polyurethane resin, polyether polyurethane, polycarbonate polyurethane resin, polyester resin, polyether resin, polyamide resin, amino resin, styrene butadiene resin, butadiene resin Rubber-based resins such as Rironitoriru resins, silicone resins, and fluorine resins.

  When a matting agent is incorporated into an optical film by coating, a conventionally known coating method [eg, die coater (extrusion coater, slide coater), roll coater (forward roll coater, reverse roll coater, gravure coater), rod Coater, blade coater, etc.] can be preferably used. In order to carry out at the temperature which does not produce the deformation | transformation of the film used as the support body of application | coating, the quality change of a coating liquid, etc., it is preferable to apply in the temperature range of 10 to 100 degreeC, and 20 to 80 degreeC is still more preferable. The coating speed is determined by appropriately adjusting depending on the viscosity of the coating solution and the coating temperature, but it is preferably performed at 10 m / min to 100 m / min, more preferably 20 m / min to 80 m / min.

  The coating layer containing the matting agent can be formed by applying a coating solution obtained by dissolving the matting agent in a suitable organic solvent to a film containing a polymer such as cellulose acylate and drying it. The matting agent can also be added to the coating liquid in the form of a dispersion. Solvents used include water, chlorinated solvents (methylene chloride, chloroform, etc.), alcohols (methanol, ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, cyclohexanone, etc.), esters (acetic acid, formic acid, Acid, maleic acid, succinic acid such as methyl, ethyl, propyl, butyl ester, etc.), aromatic hydrocarbon (benzene, toluene, xylene, etc.), amide (dimethylformamide, dimethylacetamide, n-methylpyrrolidone, etc.) preferable.

  The matting agent contained in the optical film to be produced, both in the method of casting the solution containing the polymer and the matting agent, and in the method of applying the matting agent dispersion to the formed film If the average particle size of the fine particles is an aggregating matting agent, the average primary particle size of the matting agent fine particles, the addition amount of the matting agent fine particles, the type of solvent to be dispersed, the addition amount of the solvent to be dispersed, the dispersion method, Known types such as type, size of disperser, dispersion time, energy per unit time that the disperser gives to the dispersion, mixing method, type of binder, amount of binder added, order of addition, and amount of dispersion charged It can be controlled by changing the dispersion conditions.

  Even when a non-aggregating matting agent is used, it is preferable to prevent unexpected aggregation by controlling the dispersion conditions as in the case of the aggregating matting agent.

  The preferable dynamic friction coefficient of the optical film to which the fine particles are added is 0.8 or less, and particularly preferably 0.5 or less. When winding in optical film formation and processing, creases and wrinkles are less likely to occur, the winding shape is not impaired, uneven tension due to creases and wrinkles does not apply to the optical film, and unintended unevenness on the film surface The dynamic friction coefficient is preferably 0.8 or less from the viewpoint that optical characteristics can be suppressed. The dynamic friction coefficient can be measured using a steel ball in accordance with a method defined by JIS or ASTM.

  In the composition of the fine particles used, an inorganic compound or a polymer compound is used, but there is no particular limitation, and two or more kinds of these fine particles can be used in combination. Examples of inorganic compounds include silicon-containing compounds, silicon dioxide, silicone, barium sulfate, manganese colloid, strontium barium sulfate, titanium oxide, zinc oxide, aluminum oxide, barium oxide, zirconium oxide, strontium oxide, antimony oxide, tin oxide. , Tin oxide / antimony, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, etc. Examples thereof include silicon dioxide such as synthetic silica obtained by chemical conversion, and titanium dioxide (rutile type and anatase type) produced by titanium slug and sulfuric acid. It can also be obtained by pulverizing from an inorganic substance having a relatively large particle size, for example, 20 μm or more, and then classifying (vibration filtration, wind classification, etc.). Among the above-mentioned inorganic compounds, the fine particles added to the optical film of the present invention are preferably compounds containing silicon or zirconium oxide, but those containing silicon can lower the turbidity and reduce the haze of the film. Further preferred. Many silicon dioxide fine particles are surface-treated with organic substances and are commercially available, but such ones are particularly preferred because they can reduce the surface haze of the film. Preferable organic substances used for the surface treatment of the silicon dioxide fine particles include halosilanes, alkoxysilanes, silazanes, siloxanes and the like. In particular, the silicone fine particles preferably have a three-dimensional network structure, and more preferably those having an alkyl group such as a methyl group bonded thereto by surface treatment.

  Examples of the silicon dioxide fine particles include, for example, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.), Excelica SE-5, SE-8, SE-15, SE Commercial products having trade names such as −5V, SE-8V, SE-15K, UF-320, UF-310, and UF-305 (manufactured by Tokuyama Co., Ltd.) can be used.

  As an example of silicone, the commercial item which has brand names, such as XC99-A8808, Tospearl 120,130,145,2000B (above GE Toshiba Silicone Co., Ltd. product), can be used, for example.

  Polymer compounds (polymer fine particles) include fluororesins such as polytetrafluoroethylene and tetrafluoroethylene perfluoroalkyl vinyl copolymers, cellulose acetate, polystyrene, polypropylene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, There are polyamide, chlorinated polyether, starch and the like, and pulverized and classified products thereof. Alternatively, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray dry method or a dispersion method, or an inorganic compound can be used.

  Moreover, the polymer compound which is a polymer of one kind or two or more kinds of monomer compounds described below may be formed into particles by various means. Specific examples of the monomer compound of the polymer compound include acrylic acid ester, methacrylic acid ester, itaconic acid diester, crotonic acid ester, maleic acid diester, and phthalic acid diester. Examples of ester residues include methyl, Ethyl, propyl, isopropyl, butyl, hexyl, 2-ethylhexyl, 2-chloroethyl, cyanoethyl, 2-acetoxyethyl, dimethylaminoethyl, benzyl, cyclohexyl, furfuryl, phenyl, 2-hydroxyethyl, 2-ethoxyethyl, glycidyl, ω -Methoxypolyethylene glycol (addition mole number 9) etc. are mentioned.

  Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl chloroacetate, vinyl methoxy acetate, vinyl phenyl acetate, vinyl benzoate, vinyl salicylate, etc. Can be mentioned. Examples of olefins include dicyclopentadiene, ethylene, propylene, 1-butene, 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, and 2,3-dimethylbutadiene.

  Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, trifluoromethyl styrene, vinyl. And benzoic acid methyl ester.

  Acrylamides include acrylamide, methyl acrylamide, ethyl acrylamide, propyl acrylamide, butyl acrylamide, tert-butyl acrylamide, phenyl acrylamide, dimethyl acrylamide, etc .; methacrylamides such as methacrylamide, methyl methacrylamide, ethyl methacrylamide, propyl methacryl Amides, tert-butylmethacrylamide, etc .; allyl compounds such as allyl acetate, allyl caproate, allyl laurate, allyl benzoate, etc .; vinyl ethers such as methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxyethyl vinyl ether, dimethyl Aminoethyl vinyl ether and the like; vinyl ketones such as methyl vinyl ketone , Phenyl vinyl ketone, methoxyethyl vinyl ketone, etc .; vinyl heterocycles such as vinyl pyridine, N-vinyl imidazole, N-vinyl oxazolidone, N-vinyl triazole, N-vinyl pyrrolidone, etc .; unsaturated nitriles such as Acrylonitrile, methacrylonitrile, etc .; polyfunctional monomers such as divinylbenzene, methylenebisacrylamide, ethylene glycol dimethacrylate, etc.

  In addition, acrylic acid, methacrylic acid, itaconic acid, maleic acid, monoalkyl itaconate (for example, monoethyl itaconate, etc.); monoalkyl maleate (for example, monomethyl maleate; styrene sulfonic acid, vinyl benzyl sulfonic acid, vinyl Sulfonic acid, acryloyloxyalkyl sulfonic acid (for example, acryloyloxymethyl sulfonic acid); methacryloyloxyalkyl sulfonic acid (for example, methacryloyloxyethyl sulfonic acid); acrylamide alkyl sulfonic acid (for example, 2-acrylamido-2-methylethane) Sulfonic acid, etc.); methacrylamide alkyl sulfonic acid (eg, 2-methacrylamide-2-methylethanesulfonic acid, etc.); acryloyloxyalkyl phosphate (eg, These acids may be alkali metal (eg, Na, K, etc.) or ammonium ion salts, and other monomeric compounds include those described in US Pat. 459,790, 3,438,708, 3,554,987, 4,215,195, 4,247,673, JP-A-57-205735 The crosslinkable monomer described in the document can be preferably used, and specific examples of such a crosslinkable monomer include N- (2-acetoacetoxyethyl) acrylamide, N- (2- (2 -Acetoacetoxyethoxy) ethyl) acrylamide and the like.

  These monomer compounds may be used alone as polymer particles, or may be used as copolymer particles obtained by combining a plurality of monomers. Of these monomer compounds, acrylic acid esters, methacrylic acid esters, vinyl esters, styrenes, and olefins are preferably used. In the present invention, particles having fluorine atoms or silicon atoms as described in JP-A Nos. 62-14647, 62-17744, and 62-17743 may be used.

  The particle composition preferably used in these polymer compounds is polystyrene, polymethyl (meth) acrylate, polyethyl acrylate, poly (methyl methacrylate / methacrylic acid = 95/5 (molar ratio), poly (styrene / styrene sulfonic acid = 95). / 5 (molar ratio), polyacrylonitrile, poly (methyl methacrylate / ethyl acrylate / methacrylic acid = 50/40/10), and the like.

  As the fine particles of the present invention, particles having reactive (particularly gelatin) groups described in JP-A No. 64-77052 and European Patent No. 307855 can also be used. Further, a large amount of an alkaline or acidic group capable of dissolving can be contained.

  Of the above-mentioned polymer compounds, the fine particles added to the optical film of the present invention are preferably fluororesins such as polytetrafluoroethylene and tetrafluoroethylene perfluoroalkyl vinyl copolymer, polyamide, polypropylene and chlorinated polyether.

  As an example of polytetrafluoroethylene, for example, commercially available products having trade names such as Lubron L-2, L-5, L-5F (manufactured by Daikin Industries, Ltd.) can be used. As an example of polyamide, for example, a commercial product having a trade name such as SP-500 (manufactured by Toray Industries, Inc.) can be used.

  The fine particles used in the present invention are preferably silicon dioxide, silicone and titanium dioxide as the inorganic compound, and the polymer compound is preferably a fluororesin such as polytetrafluoroethylene, polyamide, polypropylene and chlorinated polyether, more preferably. Is a fluororesin such as silicon dioxide, silicone and polytetrafluoroethylene, particularly preferably silicon dioxide and silicone which have been surface-treated with an organic substance.

  In the present invention, when a fine particle dispersion is used at the time of adding fine particles, it is desirable to filter the fine particle dispersion. After filtration, the fine particle dispersion does not stagnate in a stock tank or the like, and does not pass through a liquid feed pump. More preferably, the cellulose acylate solution is transferred by a conduit and mixed with an in-line mixer. Thereby, there is no stagnation of both liquids and generation of new aggregates due to the liquid feed pump, which is preferable. It is preferable to perform said filtration with the filter arrange | positioned just before an in-line mixer. Filter media include particle packed beds, wire mesh (especially tatami folding), woven fabric, filter paper, perforated plates (including micropores), etc., as long as they can be used for a long time with a certain absolute filtration accuracy. Although there is no particular limitation, metallicity is preferable from the viewpoint of solvent resistance and durability, and stainless steel is more preferable. From the viewpoint of clogging, the absolute filtration accuracy is preferably 10 to 100 μm, more preferably 30 to 60 μm, which enables long-term use with constant absolute filtration accuracy.

(Deterioration inhibitor)
The optical film of the present invention has a known deterioration (oxidation) inhibitor such as 2,6-di-t-butyl, 4-methylphenol, 4,4′-thiobis- (6-t-butyl-3-methyl). Phenol), 1,1′-bis (4-hydroxyphenyl) cyclohexane, 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, pentaerythrityl- A phenolic or hydroquinone antioxidant such as tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate can be added. Further, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, bis (2,6-di-t It is preferable to use a phosphorus-based antioxidant such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite.
The addition amount of the antioxidant is preferably 0.05 to 5.0 parts by mass with respect to 100 parts by mass of cellulose acylate.

(UV absorber)
In the optical film of the present invention, an ultraviolet absorber is preferably used from the viewpoint of preventing deterioration of a polarizing plate or liquid crystal. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having a small absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specific examples of ultraviolet absorbers preferably used in the present invention include, for example, hindered phenol compounds, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds Etc. Examples of hindered phenol compounds include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert) -Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. Examples of benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6 (2H-benzotriazol-2-yl) phenol), (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5- Triazine, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4- Hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, (2 (2'-hydroxy-3', 5'-di-tert-amylphenyl) -5-chloro And benzotriazole, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like. The addition amount of the ultraviolet light inhibitor is preferably 0.0001 to 1.0 part by mass, more preferably 0.001 to 0.1 part by mass with respect to 100 parts by mass of the cellulose acylate.

(Peeling accelerator)
As additives for reducing the peel resistance of optical films, many surfactants having a remarkable effect are found. As preferred release agents, phosphate ester surfactants, carboxylic acid or carboxylate surfactants, sulfonic acid or sulfonate surfactants, and sulfate ester surfactants are effective. A fluorine-based surfactant in which part of the hydrogen atoms bonded to the hydrocarbon chain of the surfactant is substituted with fluorine atoms is also effective. Examples of the release agent are given below.

RZ-1 C ₈ H ₁₇ O—P (═O) — (OH) ₂
RZ-2 C ₁₂ H ₂₅ O—P (═O) — (OK) ₂
RZ-3 C ₁₂ H ₂₅ OCH ₂ CH ₂ O—P (═O) — (OK) ₂
RZ-4 C ₁₅ H ₃₁ (OCH ₂ CH ₂ ) ₅ O—P (═O) — (OK) _{2
RZ-5 {C 12 H 25} O (CH 2 CH 2 O) 5} 2 -P (= O) -OH
_{RZ-6 {C 18 H 35} (OCH 2 CH 2) 8 O} 2 -P (= O) -ONH 4
_{RZ-7 (t-C 4} H 9) 3 -C 6 H 2 -OCH 2 CH 2 O-P (= O) - (OK) 2
_{RZ-8 (iso-C 9} H 19 -C 6 H 4 -O- (CH 2 CH 2 O) 5 -P (= O) - (OK) (OH)
RZ-9 C ₁₂ H ₂₅ SO ₃ Na
RZ-10 C ₁₂ H ₂₅ OSO ₃ Na
RZ-11 C ₁₇ H ₃₃ COOH
RZ-12 C ₁₇ H ₃₃ COOH · N (CH ₂ CH ₂ OH) _{3
RZ-13 iso-C 8 H} 17 -C 6 H 4 -O- (CH 2 CH 2 O) 3 - (CH 2) 2 SO 3 Na
_{RZ-14 (iso-C 9} H 19) 2 -C 6 H 3 -O- (CH 2 CH 2 O) 3 - (CH 2) 4 SO 3 Na
RZ-15 sodium triisopropyl naphthalene sulfonate RZ-16 sodium tri-t-butyl naphthalene sulfonate RZ-17 C ₁₇ H ₃₃ CON (CH ₃ ) CH ₂ CH ₂ SO ₃ Na
RZ-18 C ₁₂ H ₂₅ -C ₆ H ₄ SO ₃ .NH ₄

  The addition amount of the release agent is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 2 parts by mass, and most preferably 0.1 to 0.5 parts by mass with respect to 100 parts by mass of cellulose acylate.

  The optical film of the present invention may further contain an ultraviolet absorber such as phenyl salicylic acid, 2-hydroxybenzophenone, triphenyl phosphate, a bluing agent for changing the color, an antioxidant, and the like. Good.

  In the optical film of the present invention, a known plasticizer such as phthalic acid esters such as dimethyl phthalate, diethyl phthalate, and dibutyl phthalate, tributyl phosphate is used for the purpose of improving stretchability when the film described later is stretched. May contain phosphate ester, aliphatic dibasic ester, glycerin derivative, glycol derivative and the like.

[Film forming method]
When producing the optical film of the present invention, the production method is not particularly limited as long as an optical film satisfying the above-mentioned formulas (1) to (6) can be obtained. It is preferable to manufacture the optical film using the method for manufacturing an optical film according to the present invention, which includes a step of increasing the film thickness. A known film forming method can be used as a method for adjusting the material before the stretching step, a method for forming a polymer raw material into a film, a drying method, a winding method, and the like. The raw material may be heated to form a melt, or the raw material may be dissolved in a solvent to form a solution.

[Melting]
The optical film of the present invention may be manufactured by melt film formation. The raw materials such as raw materials such as polymers and additives may be heated and melted, and then extruded to form a film by injection molding. Alternatively, the raw materials are sandwiched between two heated plates and pressed to form a film. You may do it.

  The temperature for heating and melting is not particularly limited as long as the raw polymer is melted uniformly. Specifically, it is heated to a temperature equal to or higher than the melting point or softening point. In order to obtain a uniform film, the polymer raw material is melted by heating to a temperature higher than the melting point of the polymer raw material, preferably 5 to 40 ° C. higher than the melting point, particularly preferably 8 to 30 ° C. higher than the melting point. preferable.

[Solution casting]
The optical film of the present invention is also particularly preferably produced by dissolving a polymer raw material and additives in a solvent and forming a solution. In particular, solution film formation can be used as an excellent film formation method from the viewpoint of improving the surface shape of the film. As a specific method for solution casting, there is no particular limitation as long as it is a method of casting on a support substrate having a smooth surface such as a metal plate, the dope solution is directly developed on the support substrate to form a film. Alternatively, a casting method using Giesa or various coating methods using a blade can be used as appropriate. The solvent can be dried by room temperature or heat drying depending on the boiling point of the solvent used. Heating and drying can be performed in a temperature range of 30 to 200 ° C., for about 5 minutes to 2 hours, in a stationary or blasted manner according to a predetermined drying state.

  When the optical film of the present invention is formed into a solution, the film can be produced using a solution (dope) in which polymer raw materials and additives are uniformly dissolved in an organic solvent. The organic solvent preferably used as the main solvent of the optical film of the present invention is preferably a solvent selected from esters, ketones, ethers having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 7 carbon atoms. The ester, ketone and ether may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent, such as an alcoholic hydroxyl group. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

[Dissolution process]
Preparation of the solution (dope) of the optical film of the present invention is not particularly limited, and it may be performed at room temperature or further by a cooling dissolution method or a high temperature dissolution method, or a combination thereof. In the present invention, preparation of the optical film solution, and further steps such as solution concentration and filtration accompanying the dissolving step can be performed in accordance with a known film dissolving method.

[Casting process and peeling process]
Next, a film production method for producing the optical film of the present invention by solution casting will be described. As the method and equipment for producing the optical film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are preferably used.
In the casting process, first, the dope (solution containing polymer raw materials and additives) prepared from the dissolving machine (kettle) is temporarily stored in the storage kettle, and bubbles contained in the dope are defoamed. To make the final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. It is carried out by casting uniformly on a metal support.
In the peeling process, after casting, the raw dry dope film (also referred to as a web) is peeled off from the metal support at a peeling point where the metal support has substantially gone around.

[Drying process, winding process]
The drying step is performed by sandwiching both ends of the obtained web with clips, transporting them with a tenter while maintaining the width, and then drying.
In the winding process, the film is subsequently transported by a roll group of a drying apparatus, dried, and wound to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose.

[Residual solvent amount of film]
When the optical film of the present invention is obtained by solution casting, it is preferable to dry under conditions where the final residual solvent amount is in the range of 0.01 to 1.5% by mass. More preferably, it is 0.01-1.0 mass%. The residual solvent amount can be expressed by the following formula.

  Residual solvent amount (% by mass) = {(MN) / N} × 100

  Here, M is the mass of the web at any point, and N is the mass when M is dried at 110 ° C. for 3 hours.

  Next, the manufacturing method of the optical film of this invention is demonstrated in detail.

[Method for producing optical film]
The method for producing an optical film of the present invention includes a stretching step for stretching one of the longitudinal direction and the width direction of the film, and a shrinking step for shrinking the other direction, and the stretching step and / or shrinking. It is necessary to increase the film thickness compared to the film thickness before the process.

[Stretching process, shrinking process]
In the method for producing an optical film of the present invention, it is necessary to increase the film thickness by balancing the direction in which the film is stretched and the direction in which the film is contracted when performing the stretching process and the shrinking process.
Stretching and shrinking can be performed by a known method such as a zone method, a roll method, or a tenter method. You may carry out by the extending | stretching method between clips. The inter-clip stretching method is a method of stretching a film by fixing both ends of a rectangular film with a fixing member such as a clip so as not to slip. Roll method stretching is also preferred. Roll stretching may be one stage or multiple stages. A parallel arrangement or a cross arrangement may be used. The roll is not particularly limited, but a jacket roll and an expander roll are preferably used.

The method for increasing the film thickness is preferably by shrinking the film by heating. The increase in film thickness is accompanied by a film shrinking process. The shrinking step according to the production method of the present invention includes both shrinkage due to an increase in film thickness and shrinkage due to film stretching. Moreover, as a film which concerns on the manufacturing method of this invention, a cellulose acylate film is preferable.
As a heating method for increasing the film thickness by heating, a method of applying air heated in the stretching or shrinking zone to the film during stretching or shrinking is preferably used. The heat treatment temperature is not particularly limited and is appropriately selected depending on the type of resin of the film to be used and a desired shrinkage rate. When a cellulose acylate film is used as the film, for example, 160 to 200 degreeC is preferable, 165-195 degreeC is more preferable, and 170-190 degreeC is still more preferable.
In addition, the heat treatment time is not particularly limited and is appropriately selected depending on the type of resin of the film to be used, the desired shrinkage rate, and the heat treatment temperature. For example, when the heat treatment temperature is within the above range, Is preferably 5 to 60 seconds, more preferably 10 to 50 seconds, and still more preferably 15 to 45 seconds.
Heating may be performed before stretching (and / or shrinkage associated with stretching), may be performed simultaneously with stretching (and / or shrinking associated with stretching), or may be performed separately (or shrinkage associated with stretching). It may be done later. Hereinafter, the shrinkage of the film by heating may be referred to as “a step of increasing the film thickness”.

  In the method for producing an optical film of the present invention, there is no particular limitation on the pulling method when the optical film is stretched or shrunk as described above. However, desired optical performance of Re and Rth and their wavelength dependence The following method can be used as an appropriate method to make the image ideal.

(Longitudinal shrinkage / width stretching)
That is, it includes a shrinking step in which the optical film is gripped and transported by the tenter clip and contracted by narrowing an interval in the transporting direction of the tenter clip, and a stretching step in which the optical film is stretched in a direction substantially perpendicular thereto. preferable. At this time, in stretching a continuous long film, it is preferable to contract in the longitudinal direction using a tenter having a structure in which the interval in the longitudinal direction of the tenter clip is narrowed while gripping and transporting, and stretch in the width direction. .

(Longitudinal stretching / width shrinkage)
Further, it is preferable to include a stretching step in which the optical film is gripped and transported by the tenter clip and stretched by widening the interval in the transport direction of the tenter clip, and a step of contracting the optical film in a direction substantially orthogonal thereto. . At this time, in stretching a continuous long film, it is preferable that the tenter clip is stretched in the longitudinal direction using a tenter having a structure in which the interval in the longitudinal direction is widened while gripping and transporting, and the width direction is contracted. .

  In the method for producing an optical film of the present invention, the heating step of heating and softening the film at a temperature near the glass transition temperature (Tg) or higher may be combined with the stretching operation. In order to lower the above Tg, a film containing an appropriate solvent (including an organic solvent or water) or a vapor of the solvent may be stretched.

  In the method for producing an optical film of the present invention, continuous stretching is preferable from the viewpoint of productivity to continuously stretch a film formed into a continuous film from the viewpoint of productivity, but it is not necessary to be continuous stretching. That is, the film-formed film may be conveyed and stretched directly by a stretching apparatus that is attached later, or the film-formed film may be wound up once and sent to a stretching apparatus again to be stretched.

  In addition, the extending | stretching which performs the extending | stretching process which extends | stretches any one of the longitudinal direction or the width direction of the above films, the shrinkage | contraction process which shrinks the other direction, and the process which increases the film thickness of a film specifically -As a shrinking device, a FITZ machine manufactured by Ichikin Kogyo Co., Ltd. can be preferably used. This apparatus is described in (Japanese Patent Laid-Open No. 2001-38802).

(Preferable draw ratio)
As described above, in the method for producing an optical film of the present invention, in order to make the Re and Rth wavelength dispersion of the optical film in a desired state, the tenter stretching step in the film width direction and the film longitudinal direction (machine transport direction) A method of undergoing a shrinking step and a step of increasing the film thickness is preferable. Alternatively, a method of undergoing a step of freely stretching in the film machine transport direction (longitudinal direction) by changing the longitudinal direction and the width direction, a step of necking in the stretching and vertical direction (lateral direction), and a step of increasing the film thickness Is also preferable.

According to such a method, Rth (550) can be lowered by increasing the refractive index in the film thickness direction while orienting the polymer chain to the side having a higher draw ratio, and desired optical performance can be achieved.
In the following description, the stretching / shrinking ratio and the change rate of the film thickness are values for the film before the stretching process and / or the shrinking process.
The magnification of the preferable extending | stretching direction (longitudinal or width direction) in this method is 1.05-5.0 times, More preferably, it is 1.1-4.0 times.

  The draw ratio in the direction (lateral direction) perpendicular to the draw direction at this time is 0.3 to 1.0 times, more preferably 0.35 to 0.95 times. (Because of shrinkage, the magnification is smaller than 1.)

  Furthermore, the change rate of the film thickness to be increased is 1.02 to 2.0 times, more preferably 1.04 to 1.8 times. (A change rate greater than 1 indicates that the film thickness has increased.)

[Aspect ratio of stretched / shrinked film]
When the distance between the fixing members that fix the film at the time of stretching and shrinking is L, the direction perpendicular to the fixing member is W, and the aspect ratio of the film shape at the time of stretching is L / W, the aspect ratio is 0.1. It is preferably 10 or less and more preferably 0.1 or more and 8.0 or less.

(Heat treatment after stretching and shrinking)
In the method for producing an optical film of the present invention, the optical film may be subjected to a heat treatment at a temperature 10 to 50 ° C. higher than the stretching and shrinking temperature after stretching and shrinking. This is a process called heat setting which is generally performed in plastics, and can increase the degree of orientation of polymer chains locally disturbed by stretching. At this time, crystal growth of a so-called polymer film can be promoted, and it can be preferably used for producing desired optical performance of the optical film of the present invention. The temperature of the heat treatment is more preferably 10 to 45 ° C. higher than the stretching and shrinking temperature, and more preferably 10 to 40 ° C. higher than the stretching and shrinking temperature. If the difference between the stretching / shrinking temperature and the temperature of the heat treatment is less than 10 ° C., the effect is small. There is also an influence and it is not preferable.

[Film thickness]
In the method for producing an optical film of the present invention, the thickness of the optical film before stretching is preferably from 10 μm to 300 μm, more preferably from 20 μm to 280 μm, and even more preferably from 40 μm to 250 μm.
The method of increasing the film thickness after stretching and shrinking is not particularly limited, but it is preferable to increase the film thickness by shrinking by heating, for example.
Moreover, the film which shrinks | contracts a film thickness by heating to the at least one surface of the optical film of this invention, and the method of increasing the film thickness of the optical film of this invention by these may be used.

[Film width]
In the method for producing an optical film of the present invention, the preferred film width before stretching and shrinking of the optical film is from 5 cm to 3 m, more preferably from 8 cm to 2.5 m, still more preferably from 10 cm to 2 m.

[Haze of film after stretching and shrinking]
The optical film is preferably transparent. In particular, the optical film after being stretched and shrunk needs to be careful because the haze tends to increase. The haze value is 0% or more and 2% or less, preferably 0% or more and 1.6% or less, and more preferably 0% or more and 1.2% or less. The total light transmittance is preferably 85% or more. The haze can be measured according to JIS K-6714 with a haze meter (HGM-2DP, Suga Test Machine).

The optical film of the present invention is preferably produced using the above-described method for producing an optical film of the present invention.
By the said manufacturing method, it becomes possible to manufacture the optical film of this invention which satisfy | fills Formula (1)-Formula (6), and it has a high contrast ratio over a wide range, and the optical film which can suppress a color shift is obtained.

[Optical compensation film]
The optical compensation film of the present invention is formed by further forming an optically anisotropic layer satisfying the following formula (7) on the above optical film of the present invention.

  (7) Re (550) = 0 to 200 (nm) and | Rth (550) | = 0 to 300 (nm)

The optically anisotropic layer is preferably composed of a liquid crystalline compound or a polymer film.
The optically anisotropic layer is not limited to a single layer structure, and may have a laminated structure in which a plurality of layers are laminated. The material of each layer may not be the same, for example, an optically anisotropic layer using a rod-like liquid crystal or an optically anisotropic layer using a discotic liquid crystal may be used alone or in combination. Moreover, the laminated body of the optically anisotropic layer which consists of a polymer film and a liquid crystalline compound may be sufficient. In consideration of the thickness, the optically anisotropic layer is preferably a layer formed by coating rather than a laminate of polymer stretched films.

(Optical compensation film including a layer in which the optically anisotropic layer is formed of a liquid crystalline compound)
When a liquid crystal compound is used for the production of the optical compensation film, since the liquid crystal compound has various alignment forms, the optical anisotropic layer prepared by fixing the liquid crystal compound in a specific alignment state is Desired optical properties are exhibited by a single layer or a laminate of a plurality of layers. That is, the optical compensation film may be an embodiment comprising a support made of the optical film of the present invention and one or more optically anisotropic layers formed on the support. The retardation of the entire optical compensation film of this aspect can be adjusted by the optical anisotropy of the optical anisotropic layer. The liquid crystal compounds can be classified into discotic liquid crystal molecules and rod-like liquid crystal molecules from the shape of the molecules, and the compounds having these molecules can be classified into discotic liquid crystal compounds and rod-like liquid crystal compounds, respectively. Furthermore, there are low molecular weight and high molecular weight types, respectively, and both can be used. When a liquid crystal compound is used for producing the optical compensation film, it is preferable to use a rod-like liquid crystal compound or a discotic liquid crystal compound, and a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal having a polymerizable group. More preferably, the compound is used.

(Optically anisotropic layer made of polymer film)
As described above, the optically anisotropic layer may be formed from a polymer film. The polymer film is formed from a polymer that can exhibit optical anisotropy. Examples of such polymers include polyolefins (eg, polyethylene, polypropylene, norbornene polymers), polycarbonate, polyarylate, polysulfone, polyvinyl alcohol, polymethacrylic acid ester, polyacrylic acid ester and cellulose ester (eg, cellulose triacetate). Tate, cellulose diacetate). Moreover, a copolymer or a polymer mixture of these polymers may be used.

  The optical anisotropy of the polymer film is preferably obtained by stretching. The stretching is preferably uniaxial stretching or biaxial stretching. Specifically, longitudinal uniaxial stretching using a difference in peripheral speed between two or more rolls, tenter stretching for grasping both sides of the polymer film and stretching in the width direction, or biaxial stretching in combination of these is preferable. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 500 μm, and most preferably 40 to 100 μm.

  Further, as the polymer film forming the optically anisotropic layer, at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide, and polyaryletherketone is used. A method in which a solution in which is dissolved in a solvent is applied to a substrate and the solvent is dried to form a film can also be preferably used. At this time, a method of stretching the polymer film and the base material to develop optical anisotropy and using it as an optical anisotropic layer can be preferably used, and the transparent film of the present invention is preferably used as the base material. Can do. Alternatively, the polymer film may be prepared on another substrate, and the polymer film may be peeled off from the substrate and then bonded to the transparent film of the present invention, and used as an optically anisotropic layer. preferable. In this method, the thickness of the polymer film can be reduced, and is preferably 50 μm or less, and more preferably 1 to 20 μm.

[Polarizer]
The polarizing plate of the present invention includes at least one of the optical film of the present invention or the optical compensation film of the present invention.
In addition, when the optical film of the present invention is used as a retardation film having optical compensation ability, the optical compensation ability can be obtained via a pressure-sensitive adhesive on a polarizing plate that has already been prepared by bonding both surfaces of a polarizing film with a protective film. A retardation film having the same may be bonded. Furthermore, the optical film of the present invention may be directly bonded to a polarizing film as a protective film for a polarizing plate. In these cases, for example, a method for producing a polyvinyl alcohol-based polarizing plate is not particularly limited, and can be produced by a general method. For example, there is a method in which the surface of an optical film is modified by alkali saponification treatment, plasma treatment, corona discharge treatment, etc., and a polyvinyl alcohol film (PVA) is dipped in an iodine solution and bonded to both surfaces of a polarizing film produced. .

In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates. However, a polarizing plate to which the optical film of the present invention is applied may be disposed in any part.
The structure of the polarizing plate of the present invention and one form of usage of the polarizing plate of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing a cross-sectional structure of an example of the polarizing plate of the present invention (for the sake of explanation, glass for a liquid crystal cell is also shown). In FIG. 1, protective films 72 and 73 are provided on both surfaces of a polarizer 71, and at least one of them is the optical film of the present invention. The polarizing plate 70 is attached to the liquid crystal cell glass 75 through the adhesive layer 74. Moreover, FIG. 2 is a figure which shows typically the cross-sectional structure of another example of the polarizing plate of this invention. The polarizing plate of the form shown in FIG. 2 is a form in which a functional layer 81 as described later is further provided on the polarizing plate 70 shown in FIG.

[Functional layer]
When the optical film of the present invention is used as a protective film for a polarizing plate and used in a liquid crystal display device, various functional layers (functional layer 81 in FIG. 2) may be provided on the surface. These are, for example, a cured resin layer (transparent hard coat layer), an antiglare layer, an antireflection layer, an easy adhesion layer, an optical compensation layer, an alignment layer, a liquid crystal layer antistatic layer, and the like. These functional layers and materials for which the optical film of the present invention can be used include surfactants, slip agents, matting agents, antistatic layers, hard coat layers, and the like. No. 2001-1745, issued on March 15, 2001, Invention Association), and are described in detail on pages 32 to 45, and can be preferably used in the present invention.

[Liquid Crystal Display]
The liquid crystal display device of the present invention includes at least one of the optical film of the present invention, the optical compensation film of the present invention, and the polarizing plate of the present invention.
In the liquid crystal display device of the present invention, the optical film, the optical compensation film, the liquid crystal cell, and the polarizing plate are preferably in close contact with each other, and a known pressure-sensitive adhesive or adhesive can be used for the close contact.

  Moreover, you may use various optical films, such as a prism sheet and a diffusion film, between members, such as said optical film, a liquid crystal cell, and a polarizing plate, in the liquid crystal display device of this invention.

  The optical film of the present invention, and the optical compensation film and polarizing plate using the optical film can be applied to liquid crystal display devices in various display modes. Typical display modes include: VA (Vertical Aligned), OCB (Optically Compensatory Bend), IPS (In-Plane Qualited), TN (Twisted Nematic), STN (Super Twisted EC), STN (Super Twisted EC). Various display modes have been proposed such as Ferroelectric Liquid Crystal (AFLC), Anti-Ferroelectric Liquid Crystal (AFLC), and Hybrid Aligned Nematic (HAN). In addition, a display mode in which the above display mode is oriented and divided has been proposed. The effect of using the film having improved physical properties of the present invention is particularly remarkable in a large screen liquid crystal display device, and in that respect, it is used in a VA mode, OCB mode, and IPS mode liquid crystal display device used for a large TV. It is particularly preferred.

  In particular, when the optical film of the present invention is used in an IPS mode liquid crystal display device, both in-plane retardation and retardation in the thickness direction are almost zero in order from the backlight side to the viewing side of the liquid crystal display device. When a certain optical film, an IPS liquid crystal cell, and the optical film of the present invention are used in combination, more preferable display performance can be obtained.

The preferred values for the in-plane retardation and the thickness direction retardation of the optical film vary slightly depending on the retardation value in the thickness direction of the liquid crystal and the average refractive index n of the liquid crystal and the optical film, but are optimized according to the purpose. It is preferable to do.
FIG. 3 shows a configuration example of the liquid crystal display device of the present invention.
In FIG. 3, protective films 72 and 73 are provided on both surfaces of a polarizer 71, and at least one of them has the optical film of the present invention. The optical film of the present invention is preferably provided on the liquid crystal cell side. A functional layer 81 is provided on the protective film 72 (observer side). The polarizing plate 70 is pasted on the liquid crystal cell glass 92 through the adhesive layer 74. The liquid crystal cell 90 is formed by sandwiching a liquid crystal layer 91 between liquid crystal cell glasses 92 and 93, and a polarizing plate 70 ′ is bonded to the light source side liquid crystal cell glass 93 via an adhesive layer 74 ′. Yes. The polarizing plate 70 ′ is formed by providing protective films 72 ′ and 73 ′ on both surfaces of the polarizer 71 ′. In this invention, what is necessary is just to have the optical film of this invention in either the polarizing plate 70 or polarizing plate 70 ', or both.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.
In the following description, the stretching / shrinking ratio and the change rate of the film thickness are values for the film before the stretching process and / or the shrinking process and before the film shrinks by heating.

[Example 1-1]
(Preparation of cellulose acylate solution CA-1)
The following composition was placed in a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution CA-1. Note that Ac = acetyl group.

――――――――――――――――――――――――――――――――――――――
(Cellulose acylate solution CA-1 composition)
――――――――――――――――――――――――――――――――――――――
Cellulose acetate with an Ac substitution degree of 2.81 100.0 parts by mass TPP (triphenyl phosphate) 7.8 parts by mass BDP (biphenyl diphenyl phosphate) 3.9 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass ――――――――――――――――――――――――――――――――――――――

(Preparation of matting agent solution MT-1)
20 parts by mass of silica particles having an average particle diameter of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were thoroughly mixed for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution MT-1.

――――――――――――――――――――――――――――――――――――――
(Matting agent solution MT-1 composition)
――――――――――――――――――――――――――――――――――――――
Silica particle dispersion with an average particle size of 16 nm 10.0 parts by mass Methylene chloride (first solvent) 76.3 parts by mass Methanol (second solvent) 3.4 parts by mass Cellulose acylate solution CA-1 10.3 parts by mass ―――――――――――――――――――――――――――――――――――――

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare an additive solution AD-1. Furthermore, the retardation developing agent (compound X) shown below was used.

――――――――――――――――――――――――――――――――――――――
(Additive solution AD-1 composition)
――――――――――――――――――――――――――――――――――――――
The following retardation developer (Compound X) 7.6 parts by mass Methylene chloride (first solvent) 58.4 parts by mass Methanol (second solvent) 8.7 parts by mass Cellulose acylate solution CA-1 12.8 parts by mass ――――――――――――――――――――――――――――――――――――――

  Compound X

(Preparation of cellulose acylate film sample 101)
The cellulose acylate solution CA-1 was mixed with 94.6 parts by mass, the matting agent solution MT-1 was 1.3 parts by mass, and the additive solution AD-1 was 2.3 parts by mass. It was cast using a machine. With the above composition, the mass ratio of the retardation developer to cellulose acylate was 1.0%. The film was peeled from the band with a residual solvent amount of 30% and dried at 140 ° C. for 40 minutes to produce a cellulose acylate film. The finished cellulose acylate film 101 had a residual solvent amount of 0.2% and a film thickness of 100 μm.

(Preparation of optical film 111)
The cellulose acylate film 101 obtained above has a step of stretching in the width direction using a tenter having a structure in which a continuous long film is narrowed while the length of the tenter clip is held and conveyed in the longitudinal direction. The film temperature is set to 180 ° C and the film temperature is set to 180 ° C. After 30 seconds, the film is passed through the heating zone and then stretched. The film lengthwise shrinks 0.85 times, and the tenter clip stretches the width direction 1.25 times. And the optical film 111 with a film thickness of 125 micrometers after extending | stretching was obtained.

[Example 1-2]

(Preparation of optical film 112)
The cellulose acylate film 101 obtained above is fed to the same stretching apparatus as in Example 1-1, stretching is started after passing through the heating zone 30 seconds after setting the film temperature to 190 ° C., the film longitudinal direction is The film was shrunk 0.85 times and stretched 1.25 times in the width direction by a tenter clip, to obtain an optical film 112 having a thickness of 135 μm after stretching.

[Example 1-3]

(Preparation of optical film 113)
The cellulose acylate film 101 obtained above was sent to the same stretching apparatus as in Example 1-1, and the film temperature was set to 175 ° C., and after 30 seconds, the film was passed through the heating zone. The film was shrunk 0.85 times and stretched 1.25 times in the width direction by a tenter clip, to obtain an optical film 113 having a film thickness of 115 μm after stretching.

[Example 1-4]

(Preparation of optical film 114)
The cellulose acylate film 101 obtained above is fed to the same stretching apparatus as in Example 1-1, stretching is started after passing through the heating zone after 30 seconds with the film temperature set to 170 ° C. The film was shrunk 0.85 times, and the width direction was stretched 1.25 times with a tenter clip to obtain an optical film 114 having a film thickness of 110 μm after stretching.

  After the film obtained in the above example was conditioned for 2 hours or more in an environment of 25 ° C. and 60% RH, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), a wavelength of 450 nm, The three-dimensional birefringence measurement was performed at 550 nm and 650 nm, and the in-plane retardation Re and the retardation Rth in the film thickness direction obtained by measuring Re by changing the tilt angle were obtained. The optical performance shown in Table 1 was obtained. I found out. The film samples described in the following examples and comparative examples were also evaluated in the same manner.

[Example 2]

(Preparation of optical film 211)
A step of stretching the cellulose acylate film 101 obtained in Example 1 in the longitudinal direction using a tenter having a structure that becomes wide while a continuous long film is held and conveyed in the longitudinal direction of the tenter clip. The film is sent to a stretching device, and the film temperature is set to 180 ° C., and after 30 seconds, the film starts to be stretched after passing through the heating zone. The film was shrunk 0.72 times to obtain an optical film 211 having a film thickness of 130 μm after stretching and the optical performance shown in Table 1.

[Example 3]
(Preparation of cellulose acylate solution CA-2)
The following composition was placed in a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution CA-2. Note that Ac = acetyl group and Pro = propionyl group.

――――――――――――――――――――――――――――――――――――――
(Cellulose acylate solution CA-2 composition)
――――――――――――――――――――――――――――――――――――――
Cellulose acylate Ac substitution degree 2.06 + Pro substitution degree 0.79 100.0 parts by mass TPP (triphenyl phosphate) 7.8 parts by mass BDP (biphenyl diphenyl phosphate) 3.9 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass ――――――――――――――――――――――――――――――――― ――――

(Preparation of matting agent solution MT-2)
20 parts by mass of silica particles having an average particle diameter of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were thoroughly mixed for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution MT-2.

――――――――――――――――――――――――――――――――――――――
(Matting agent solution MT-2 composition)
――――――――――――――――――――――――――――――――――――――
Silica particle dispersion with an average particle size of 16 nm 10.0 parts by mass Methylene chloride (first solvent) 76.3 parts by mass Methanol (second solvent) 3.4 parts by mass Cellulose acylate solution CA-2 10.3 parts by mass ―――――――――――――――――――――――――――――――――――――

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare an additive solution AD-2. Furthermore, the retardation developing agent (compound X; discotic compound (446)) shown below was used.

――――――――――――――――――――――――――――――――――――――
(Additive solution AD-2 composition)
――――――――――――――――――――――――――――――――――――――
The following retardation developer (Compound X) 7.6 parts by mass Methylene chloride (first solvent) 58.4 parts by mass Methanol (second solvent) 8.7 parts by mass Cellulose acylate solution CA-2 12.8 parts by mass ――――――――――――――――――――――――――――――――――――――

  Compound X

(Preparation of Cellulose Acylate Film Sample 301)
94.6 parts by mass of the cellulose acylate solution CA-2, 1.3 parts by mass of the matting agent solution MT-2, and 2.3 parts by mass of the additive solution AD-2 were mixed after filtration, and the band was cast. It was cast using a machine. With the above composition, the mass ratio of the retardation developer to cellulose acylate was 1.0%. The film was peeled from the band with a residual solvent amount of 30% and dried at 140 ° C. for 40 minutes to produce a cellulose acylate film. The finished cellulose acylate film had a residual solvent amount of 0.2% and a film thickness of 100 μm.

(Preparation of optical film 311)
The cellulose acylate film 301 obtained above is sent out to the same stretching apparatus as in Example 1-1, the film temperature is set to 160 ° C., and after 30 seconds, the film is passed through the heating zone. The film was shrunk 0.84 times, and the width direction was stretched 1.25 times with a tenter clip to obtain an optical film 311 having a film thickness of 125 μm after stretching and optical performance shown in Table 1.

[Example 4]
(Preparation of cellulose acylate solution CA-3)
The following composition was placed in a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution CA-3. Note that Ac = acetyl group.

――――――――――――――――――――――――――――――――――――――
(Cellulose acylate solution CA-3 composition)
――――――――――――――――――――――――――――――――――――――
Cellulose acetate having an Ac substitution degree of 2.92 100.0 parts by mass TPP (triphenyl phosphate) 7.8 parts by mass BDP (biphenyl diphenyl phosphate) 3.9 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass ――――――――――――――――――――――――――――――――――――――

(Preparation of matting agent solution MT-3)
20 parts by mass of silica particles having an average particle diameter of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were thoroughly mixed for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution MT-3.

――――――――――――――――――――――――――――――――――――――
(Matting agent solution MT-3 composition)
――――――――――――――――――――――――――――――――――――――
Silica particle dispersion liquid having an average particle size of 16 nm 10.0 parts by mass Methylene chloride (first solvent) 76.3 parts by mass Methanol (second solvent) 3.4 parts by mass Cellulose acylate solution CA-3 10.3 parts by mass ―――――――――――――――――――――――――――――――――――――

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare an additive solution AD-3. Furthermore, the retardation developing agent (compound Y; rod-shaped compound (41)) shown below was used.

――――――――――――――――――――――――――――――――――――――
(Additive solution AD-3 composition)
――――――――――――――――――――――――――――――――――――――
Retardation expression agent (Compound Y) 7.6 parts by mass Methylene chloride (first solvent) 58.4 parts by mass Methanol (second solvent) 8.7 parts by mass Cellulose acylate solution CA-3 12.8 parts by mass ――――――――――――――――――――――――――――――――――――――

  Compound Y

(Preparation of Cellulose Acylate Film Sample 401)
94.6 parts by mass of the cellulose acylate solution CA-3, 1.3 parts by mass of the matting agent solution MT-3, and 2.3 parts by mass of the additive solution AD-3 were mixed after filtration, and the band was cast. It was cast using a machine. In the above composition, the mass ratio of retardation developer Y to cellulose acylate was 1.0%. The film was peeled from the band with a residual solvent amount of 30% and dried at 140 ° C. for 40 minutes to produce a cellulose acylate film. The finished cellulose acylate film had a residual solvent amount of 0.2% and a film thickness of 100 μm.

(Preparation of optical film 411)
The cellulose acylate film 401 obtained above is sent out to the same stretching apparatus as in Example 1-1, stretching is started after passing through the heating zone 30 seconds after setting the film temperature to 180 ° C., and the longitudinal direction of the film is The film has a thickness of 140 μm after stretching and the optical performance shown in Table 1, except that the film is contracted 0.70 times and the width direction is stretched 1.32 times with a tenter clip. An optical film 411 was obtained.

[Comparative Example 1]

(Preparation of comparative sample 001)
The cellulose acylate film 101 obtained in Example 1-1 was fixed uniaxially stretched. Stretching was started after passing through the heating zone 30 seconds after setting the temperature of the film 101 to 180 ° C., the film longitudinal direction was fixed and held at 1.00 times, and the width direction was stretched 1.25 times by a tenter clip, A comparative sample film 001 having a film thickness of 92 μm after stretching and the optical performance shown in Table 1 was obtained.

[Comparative Example 2]

(Preparation of comparative sample 002)
The cellulose acylate film 101 obtained in Example 1-1 was fixed uniaxially stretched. Stretching was started after passing through the heating zone 30 seconds after setting the temperature to 180 ° C., the film longitudinal direction was fixed and held at 1.00 times, and the width direction was stretched 1.10 times by a tenter clip. A comparative sample film 002 having a film thickness of 95 μm after stretching and optical performance shown in Table 1 was obtained.

[Comparative Example 3]

(Preparation of comparative sample 003)
The cellulose acylate film 401 obtained in Example 4 was fixed uniaxially stretched. Stretching was started after passing through the heating zone 30 seconds after setting the temperature at 180 ° C., the film longitudinal direction was fixed and held at 1.00 times, and the width direction was stretched 1.35 times by a tenter clip. A comparative sample film 003 having a film thickness of 72 μm after stretching and the optical performance shown in Table 1 was obtained.

  Table 1 shows the composition of the optical film of the present invention, the film forming method, the optical characteristics, and the performance when mounted on a liquid crystal display device.

(Polarizing plate processing)
The optical film sample of the present invention obtained in the above examples and the sample obtained in the comparative example were bonded together using a commercially available polarizing plate (HLC2-5618, manufactured by Sanlitz Co., Ltd.) and an adhesive, and a retardation film. It was processed into an integrated polarizing plate.

[Example 5]
(Evaluation of mounting on IPS panel)
A polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film. Next, the surface of the optical film 111 produced in Example 1 was immersed in an aqueous 1.5 N sodium hydroxide solution at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing tub, and neutralized using 0.1 N sulfuric acid at 30 degreeC. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. In this way, the surface of the cellulose acylate film was saponified. This alkali saponified optical film 111 was attached to one side of a polarizer using a polyvinyl alcohol-based adhesive. At this time, the slow axis of the optical film 111 and the transmission axis of the polarizer were arranged in parallel. As a protective film, a commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was similarly saponified, and using a polyvinyl alcohol adhesive, the opposite side of the polarizer (no optical film was attached). Affixed to the side). In this way, a polarizing plate integrated retardation film was produced. A polarizing plate integrated retardation film was prepared for Example Sample 114 and Comparative Samples 001 to 003 by the same operation.

  A polarizing plate integrated retardation film produced as described above, an IPS type liquid crystal cell, and a commercially available polarizing plate (HLC2-5618, manufactured by Sanlitz Co., Ltd.) are stacked in order from above and attached using an adhesive. In addition, a display device having the layer structure of FIG. At this time, the transmission axes of the upper and lower polarizing plates are orthogonal to each other, and the transmission axis of the upper polarizing plate is parallel to the molecular long axis direction of the liquid crystal cell (that is, the slow axis of the optical compensation layer and the molecular long axis direction of the liquid crystal cell are orthogonal). ). As the liquid crystal cell, electrode and substrate, those conventionally used as IPS can be used as they are. The alignment of the liquid crystal cell is horizontal alignment, and the liquid crystal has a positive dielectric anisotropy, and those developed and marketed for IPS liquid crystals can be used. The physical properties of the liquid crystal cell were as follows: Δn of liquid crystal: 0.099, cell gap of liquid crystal layer: 3.0 μm, pretilt angle: 5 degrees, rubbing direction: 75 degrees on both upper and lower sides of the substrate. In FIG. 4, the protective tack means a protective film.

(Panel color viewing angle evaluation)
With respect to each sample mounted on the liquid crystal display device with the layer configuration shown in FIG. 4, the color change in the oblique direction from the azimuth angle of 45 degrees and the polar angle of 60 degrees when the screen was displayed in black was evaluated. In the color evaluation, in the color evaluation, ○ indicates no change in color (yellowness or redness), Δ indicates a change in color at a polar angle of 60 degrees, but the polar angle is 60 degrees When the angle is returned from 30 degrees to 30 degrees, the color change disappears, and x indicates a clear color change at any polar angle. None of the samples using the optical films 111 and 114 of the present invention produced in the examples had any coloration (change in color) even when viewed obliquely, and no light leakage was observed. On the other hand, when the samples 001 to 003 of the comparative example were viewed from an oblique direction, light leakage was remarkable, and coloring of the leaking light (slightly reddish) could be confirmed. Further, the measurement was performed when the screen was displayed in white, and the contrast ratio with the black display was determined. As a result, it was found that all of the optical films of the present invention had an excellent contrast ratio.

[Example 6]
(Evaluation of mounting on IPS panel)
A polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film. Next, the surface of the optical film 111 produced in Example 1 was immersed in an aqueous 1.5 N sodium hydroxide solution at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing tub, and neutralized using 0.1 N sulfuric acid at 30 degreeC. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. In this way, the surface of the cellulose acylate film was saponified. This alkali saponified optical film 111 was attached to one side of a polarizer using a polyvinyl alcohol-based adhesive. At this time, the slow axis of the optical film 111 and the transmission axis of the polarizer were arranged in parallel. As a protective film, a commercially available cellulose triacetate film (ZRF80S, manufactured by FUJIFILM Corporation) having Re (550) = 0 nm and Rth (550) = 0 nm was similarly saponified, and a polyvinyl alcohol adhesive was used. Then, it was pasted on the opposite side of the polarizer (the side on which the optical film was not pasted). In this way, a polarizing plate integrated retardation film was produced. A polarizing plate integrated retardation film was prepared for Example Sample 114 and Comparative Samples 001 to 003 by the same operation.

  A polarizing plate integrated retardation film produced as described above, an IPS type liquid crystal cell, and a commercially available polarizing plate (HLC2-5618, manufactured by Sanlitz Co., Ltd.) are stacked in order from above and attached using an adhesive. In addition, a display device having the layer structure of FIG. At this time, the transmission axes of the upper and lower polarizing plates are orthogonal to each other, and the transmission axis of the upper polarizing plate is parallel to the molecular long axis direction of the liquid crystal cell (that is, the slow axis of the optical compensation layer and the molecular long axis direction of the liquid crystal cell are orthogonal). ). As the liquid crystal cell, electrode and substrate, those conventionally used as IPS can be used as they are. The alignment of the liquid crystal cell is horizontal alignment, and the liquid crystal has a positive dielectric anisotropy, and those developed and marketed for IPS liquid crystals can be used. The physical properties of the liquid crystal cell were as follows: Δn of liquid crystal: 0.099, cell gap of liquid crystal layer: 3.0 μm, pretilt angle: 5 degrees, rubbing direction: 75 degrees on both upper and lower sides of the substrate. In FIG. 4, the protective tack means a protective film.

(Panel color viewing angle evaluation)
With respect to each sample mounted on the liquid crystal display device with the layer configuration shown in FIG. 4, the color change in the oblique direction from the azimuth angle of 45 degrees and the polar angle of 60 degrees when the screen was displayed in black was evaluated. In the color evaluation, in the color evaluation, ○ indicates no change in color (yellowness or redness), Δ indicates a change in color at a polar angle of 60 degrees, but the polar angle is 60 degrees When the angle is returned from 30 degrees to 30 degrees, the color change disappears, and x indicates a clear color change at any polar angle. None of the samples using the optical films 111 and 114 of the present invention produced in the examples had any coloration (change in color) even when viewed obliquely, and no light leakage was observed. On the other hand, when the samples 001 to 003 of the comparative example were viewed from an oblique direction, light leakage was remarkable, and coloring of the leaking light (slightly reddish) could be confirmed. Further, the measurement was performed when the screen was displayed in white, and the contrast ratio with the black display was determined. As a result, it was found that all of the optical films of the present invention had an excellent contrast ratio.

  As described above, the optical film having the desired performances of Re and Rth of the present invention has a high contrast ratio over a wide range and produces a film that also functions as a retardation film capable of suppressing color change. It was possible to provide a polarizing plate using these and a liquid crystal display device.

It is a figure which shows typically the cross-sectional structure of an example of the polarizing plate of this invention. It is a figure which shows typically the cross-sectional structure of another example of the polarizing plate of this invention. It is a figure which shows the structural example of the liquid crystal display device of this invention. It is a figure for demonstrating the layer structure of the liquid crystal panel employ | adopted in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 70 Polarizing plate 71 Polarizer 72, 73 Protective film 74 Adhesive layer 75 Glass for liquid crystal cell 81 Functional layer

Claims (13)

An optical film characterized by satisfying the following formulas (1) to (6).
(1) 150 ≦ Re (550) ≦ 400
(2) −100 ≦ Rth (550) ≦ 100
(3) 0.1 <Re (450) / Re (550) <0.95
(4) 1.03 <Re (650) / Re (550) <1.93
(5) 0.4 <(Re (450) / Rth (450)) / (Re (550) / Rth (550)) <0.95
(6) 1.05 <(Re (650) / Rth (650)) / (Re (550) / Rth (550)) <1.90
(In formulas (1) to (6), Re (450), Re (550), and Re (650) are in-plane retardation values (unit: nm) measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively. Rth (450), Rth (550), and Rth (650) are retardation values (unit: nm) in the thickness direction measured with light having wavelengths of 450 nm, 550 nm, and 650 nm, respectively.   The optical film according to claim 1, wherein the optical film contains cellulose acylate.   The optical film according to claim 1, wherein the optical film has a thickness of 10 to 300 μm.   A stretching process for stretching one of the longitudinal direction and the width direction of the film, and a shrinking process for contracting the other direction, and the film is compared with the film thickness before the stretching process and / or the shrinking process. A method for producing an optical film, wherein the thickness is increased.   The method for producing an optical film according to claim 4, wherein the film thickness is increased by contraction by heating.   A shrinking step of gripping and transporting the film with a tenter clip and shrinking by narrowing an interval in the transporting direction of the tenter clip, and a stretching step of stretching the film in a direction substantially perpendicular thereto. Item 6. The method for producing an optical film according to Item 4 or 5.   A stretching step of gripping and transporting a film by a tenter clip and stretching by widening an interval in a transport direction of the tenter clip, and a step of contracting the film in a direction substantially perpendicular thereto. 6. A method for producing an optical film according to 4 or 5.   An optical film produced by the production method according to any one of claims 4 to 7. An optical compensation film obtained by further forming an optically anisotropic layer satisfying the following formula (7) on the optical film according to claim 1.
(7) Re (550) = 0 to 200 (nm) and | Rth (550) | = 0 to 300 (nm)   A polarizing plate comprising at least one of the optical film according to claim 1, or the optical compensation film according to claim 9.   It includes any one of the optical film according to any one of claims 1 to 3 or claim 8, the optical compensation film according to claim 9, and the polarizing plate according to claim 10. Liquid crystal display device.   The liquid crystal display device according to claim 11, wherein the liquid crystal cell is in an IPS mode. A liquid crystal display device comprising: the polarizing plate according to claim 10; a polarizing plate having an optical film satisfying the following formula (8) as a protective film for the polarizing plate; and an IPS cell.
(8) | Re (550) | = 0 to 10 (nm) and | Rth (550) | = 0 to 25 (nm)

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