JP2011232428A - Inclined retardation film and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inclined retardation film having high uniformity, and a liquid crystal display device which is superior in a view angle and color shift characteristics.SOLUTION: In the inclined retardation film, wavelength dispersion L40 observed from the direction with 40° inclination from a normal direction of a film surface is 0.9 or more and 1.09 or less, an average inclination angle β1 is 50°or more and 85°or less, refractive index ellipsoid in-plane retardation Ro' satisfies 0≤Ro'≤80 nm, and refractive index ellipsoid thickness retardation Rth' satisfies -200≤Rth'≤-30 nm.

Description

  The present invention relates to a retardation film used for liquid crystal display and the like and a liquid crystal display device using the retardation film.

  When a biaxial retardation film is used for general-purpose optical compensation in a TN type liquid crystal display device (TN type LCD), the upper and lower viewing angles are not sufficiently widened, and improvement as a monitor for a personal computer or the like is necessary.

  On the other hand, in Patent Document 1, the polycarbonate film is sheared by a metal roll or a metal belt, and the upper and lower visual fields are obtained by using a retardation film that develops an inclined retardation by tilting the optical axis in the film thickness direction. It is shown that the corners widen.

  Similarly, production of a retardation film having an inclined optical axis has been attempted for cellulose ester films, polyimide films, and the like (Patent Documents 2 and 3), and it has been shown that the viewing angle is also improved.

  In Patent Document 4, a technique using a thermoplastic norbornene resin (a type of polycycloolefin film) instead of a polycarbonate, polyester or cellulose ester film in which the uniformity of retardation is unstable due to a large intrinsic birefringence. It is disclosed.

  TN LCDs using retardation films produced by these manufacturing methods have the effect of improving the upper and lower viewing angles that are lacking when biaxial retardation films are used. Is a problem.

  The cause of the non-uniformity is considered to be due to the non-uniformity of how the metal roller or metal belt contacts the film itself in the shearing process.

  In the metal roller method that performs shearing processing in a short time, the contact time between the film and the metal roller is very short, but the tilt orientation processing must be performed within that time, and the processing method itself is uneven. It is an easy method.

  In addition, in order to increase the width and increase the production speed, it is necessary to increase the pressure during the treatment, which is a method of increasing the burden on the equipment. Even when a metal belt is used, if the production speed is increased, it is necessary to increase the pressure at the time of processing, and the same problem occurs.

  On the other hand, an optical compensation film is known in which liquid crystal molecules are applied to the surface of a base material and are tilted or hybrid-oriented (Patent Document 5). Although there is some improvement in black display unevenness by using this optical compensation film, there are problems such as complicated manufacturing processes, coating failures and orientation defects, and poor yield. It cannot be called a certain manufacturing method.

  In addition, the display device includes an optical compensation film including a layer in which liquid crystal molecules are inclined or hybrid-aligned as described above, and the white display portion is yellowish or reddish when viewed from an oblique direction when tilted from the vertical direction. There is a problem that the color shift appears to deteriorate and the display quality is remarkably deteriorated.

JP 2003-25414 A JP 2003-315557 A JP 2005-17328 A JP 2007-38646 A JP 2009-98645 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a retardation film and a liquid crystal display device with improved viewing angle and color shift when viewed from an oblique direction in a TN type LCD.

  The object of the present invention has been achieved by the following means.

  1. The chromatic dispersion L40 observed from the direction inclined by 40 ° from the normal direction of the film surface is 0.9 to 1.09, the average inclination angle β1 is 50 ° to 85 °, and the refractive index ellipsoid in-plane retardation Ro. An inclined retardation film, wherein “is 0 ≦ Ro ′ ≦ 80 nm and refractive index ellipsoid thickness retardation Rth ′ is −200 ≦ Rth ′ ≦ −30 nm.

  Here, when the short direction of the inclined retardation film is a ′, the long direction is b ′, and the thickness direction axis is c ′, the average inclination angle β1 is the long direction b ′ of the inclined retardation film and the thickness direction. It is an average value in the thickness direction of the angle formed by the major axis of the ellipsoid and the longitudinal direction b ′ in the cross section of the refractive index ellipsoid of the inclined retardation film on the b′c ′ plane of the axis c ′. .

  The wavelength dispersion L40 is a ratio of retardation values observed from a direction inclined by 40 ° in any direction from the normal direction of the film surface, R40 ′ (480) / R40 ′ (630). The values in parentheses represent the measurement light wavelength (nm).

Ro ′ = (nx′−ny ′) × d1
Rth ′ = {(nx ′ + ny ′) / 2−nz ′} × d1
Further, in the cross section of the refractive index ellipsoid of the tilted phase difference film in the b′c ′ plane of the tilted phase difference film, of the major axis and the minor axis of the ellipsoidal section, the thickness direction axis c ′ of the film The axis with the smaller angle is the z ′ axis, the refractive index in that direction is nz ′, the plane having the maximum refractive index among the planes orthogonal to the z ′ axis is the x ′ axis, and the refractive index in that direction is nx. Of the plane orthogonal to the z ′ direction of the refractive index ellipsoid, the direction in which the refractive index is minimum is the y ′ axis, the refractive index in that direction is ny ′, and the thickness of the tilted retardation film is d1 (nm) To express. The measurement wavelength is 590 nm.

  2. 2. The inclined retardation film as described in 1 above, wherein the inclined retardation film is an inclined retardation film 1 and contains a compound having negative intrinsic birefringence.

  3. The chromatic dispersion L40 observed from the direction inclined by 40 ° from the normal direction of the film surface is 0.9 to 1.09, the average inclination angle β1 is 50 ° to 85 °, and the refractive index ellipsoid in-plane retardation Ro. Inclined retardation film 1 in which “is 0 ≦ Ro ′ ≦ 80 nm and refractive index ellipsoidal thickness retardation Rth ′ is −200 ≦ Rth ′ ≦ −30 nm, 10 ≦ Ro ≦ 100 nm, 20 ≦ Rth ≦ 230 nm and the surface A liquid crystal display device having a laminated retardation film configuration with a retardation film 2 having a wavelength dispersion L of an inner retardation of 0.9 or more and less than 1.0.

Ro ′ = (nx′−ny ′) × d1
Rth ′ = {(nx ′ + ny ′) / 2−nz ′} × d1
Here, when the short direction of the inclined retardation film 1 is a ′, the long direction is b ′, and the thickness direction axis is c ′, the average inclination angle β1 is the long direction b ′ of the inclined retardation film 1. The average in the thickness direction of the angle formed by the major axis of the ellipsoid and the longitudinal direction b ′ in the cross section of the refractive index ellipsoid of the inclined retardation film 1 on the b′c ′ plane of the thickness direction axis c ′. Value.

  The wavelength dispersion L40 is a ratio of retardation values observed from a direction inclined by 40 ° in any direction from the normal direction of the film surface, R40 ′ (480) / R40 ′ (630). The values in parentheses represent the measurement light wavelength (nm).

  The wavelength dispersion L40 is a ratio of retardation values observed from a direction inclined by 40 ° in any direction from the normal direction of the film surface, R40 ′ (480) / R40 ′ (630). The values in parentheses represent the measurement light wavelength (nm).

Ro = (nx−ny) × d2
Rth = {(nx + ny) / 2−nz} × d2
Here, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the retardation film 2, and ny is in the direction y orthogonal to the direction x in the in-plane direction of the retardation film 2. The refractive index is represented, nz represents the refractive index in the thickness direction z of the retardation film 2, and d2 (nm) represents the thickness of the retardation film 2.

  The chromatic dispersion L is Ro (480) / Ro (630). The values in parentheses represent the measurement light wavelength (nm).

  4). Ro ″, Rth ″ of the refractive index ellipsoid of the laminated retardation film configuration is 20 ≦ Ro ″ ≦ 100 nm, 70 ≦ Rth ″ ≦ 200 nm, and the average inclination angle βo is 10 ≦ βo ≦ 45 °. 4. The liquid crystal display device according to 3 above.

  Here, when the in-plane slow axis of the laminated retardation film is a, the in-plane fast axis is b, and the thickness direction axis is c, the average inclination angle βo is the in-plane fast axis of the laminated retardation film. This is the average value in the thickness direction of the angle formed by the major axis of the ellipsoid and the in-plane fast axis b in the cross section of the refractive index ellipsoid of the laminated retardation film on the bc plane of the thickness direction axis c. .

  In the cross section of the refractive index ellipsoid of the laminated phase difference film in the bc plane of the laminated phase difference film, Ro ″ and Rth ″ of the refractive index ellipsoid are the laminating positions of the major axis and the short axis of the ellipsoidal cross section. The axis having the smaller angle with respect to the thickness direction axis c of the retardation film is defined as the z ″ axis, the refractive index in that direction is nz ″, and the direction in which the refractive index is maximum among the planes orthogonal to the z ″ axis direction is x “Axis, the refractive index in that direction is nx”, and the z ”axis direction of the refractive index ellipsoid is the direction in which the refractive index is the smallest in the y” axis, and the refractive index in that direction is ny ”, It is expressed as follows. The measurement wavelength is 590 nm.

Ro ″ = (nx ″ −ny ″) × (d1 + d2)
Rth ″ = {(nx ″ + ny ″) / 2−nz ″} × (d1 + d2)

  According to the present invention, a retardation film having an improved color shift when viewed from a viewing angle and an oblique direction in a TN type LCD can be obtained.

It is a perspective view of the inclination retardation film 1 of this invention. It is sectional drawing of the inclination retardation film 1 of this invention. It is a schematic diagram of a TN type liquid crystal display device of the present invention. It is the schematic of the whole inclination orientation processing apparatus of this invention.

<Inclined retardation film 1 of the present invention>
The tilt retardation film 1 of the present invention has a wavelength dispersion L40 of 0.9 to 1.09 and an average tilt angle β1 of 50 ° to 85 ° observed from a direction inclined by 40 ° from the normal direction of the film surface. The refractive index ellipsoid in-plane retardation Ro ′ is 0 ≦ Ro ′ ≦ 80 nm, and the refractive index ellipsoid thickness retardation Rth ′ is −200 ≦ Rth ′ ≦ −30 nm.

  Here, when the short direction of the inclined retardation film 1 is a ′, the long direction is b ′, and the thickness direction axis is c ′, the average inclination angle β1 is the long direction b ′ of the inclined retardation film 1. The average in the thickness direction of the angle formed by the major axis of the ellipsoid and the longitudinal direction b ′ in the cross section of the refractive index ellipsoid of the inclined retardation film 1 on the b′c ′ plane of the thickness direction axis c ′. Value.

  The wavelength dispersion L40 is a ratio of retardation values observed from a direction inclined by 40 ° in any direction from the normal direction of the film surface, R40 ′ (480) / R40 ′ (630). The values in parentheses represent the measurement light wavelength (nm).

Ro ′ = (nx′−ny ′) × d1
Rth ′ = {(nx ′ + ny ′) / 2−nz ′} × d1
Further, in the cross section of the refractive index ellipsoid of the inclined retardation film 1 in the b′c ′ plane of the inclined retardation film 1, the film thickness direction axis c ′ of the major axis and the minor axis of the ellipsoidal section. The axis with the smaller angle is z′-axis, the refractive index in that direction is nz ′, and the plane having the maximum refractive index among the planes orthogonal to the z′-axis is the x′-axis, and the refractive index in that direction Nx ′, among the planes orthogonal to the z ′ direction of the refractive index ellipsoid, the direction in which the refractive index is minimum is the y ′ axis, the refractive index in that direction is ny ′, and the thickness of the tilted retardation film 1 is d1 ( nm). The measurement wavelength is 590 nm.

  FIG. 1 is a perspective view in which a refractive index ellipsoid is superimposed on the inclined retardation film 1 of the present invention. When the short direction of the inclined retardation film 1 is a ′, the long direction is b ′, and the thickness direction axis is c ′, the slow axis x ′ or y ′ overlaps with the short direction a ′ of the inclined retardation film 1. Z ′ is the axis with the smaller angle between c ′ and the major axis and minor axis of the refractive index ellipsoid of the inclined retardation film 1 on the b′c ′ plane.

  Which of the slow axis x 'and the fast axis y' overlaps with a 'varies depending on the shape of the refractive index ellipsoid of the inclined retardation film 1 of the present invention and β1. In FIG. 1, since the angle θ2 formed between the short axis and the c ′ axis is smaller than the angle θ1 formed between the long axis and the c ′ axis, the long axis is the z ′ axis.

  FIG. 2 is a cross-sectional view of the refractive index ellipsoid in the b′c ′ plane of the inclined retardation film 1. β1 is an angle formed by the major axis and the b ′ axis.

  The inclined retardation film 1 contains a compound having negative intrinsic birefringence.

  In the liquid crystal display device of the present invention, the wavelength dispersion L40 observed from a direction inclined by 40 ° from the normal direction of the film surface is 0.9 or more and 1.09 or less, and the average inclination angle β1 is 50 ° or more and 85 ° or less, An inclined retardation film 1 having a refractive index ellipsoid in-plane retardation Ro ′ of 0 ≦ Ro ′ ≦ 80 nm and a refractive index ellipsoid thickness retardation Rth ′ of −200 ≦ Rth ′ ≦ −30 nm, and 10 ≦ Ro ≦ 100 nm. 20 ≦ Rth ≦ 230 nm, and a retardation retardation film 2 and a retardation retardation film 2 having a wavelength dispersion L of in-plane retardation of 0.9 or more and less than 1.0,

Ro = (nx−ny) × d2
Rth = {(nx + ny) / 2−nz} × d2
Here, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the retardation film 2, and ny is in the direction y orthogonal to the direction x in the in-plane direction of the retardation film 2. The refractive index is represented, nz represents the refractive index in the thickness direction z of the retardation film 2, and d2 (nm) represents the thickness of the retardation film 2. The chromatic dispersion L of the in-plane retardation of the retardation film 2 is Ro (480) / Ro (630). The values in parentheses represent the measurement light wavelength (nm).

  The tilt retardation film in the liquid crystal display device of the present invention is the tilt retardation film 1 described above.

  The laminated retardation film structure in the liquid crystal display device of the present invention is such that Ro ″ and Rth ″ of the refractive index ellipsoid as the entire laminated retardation film structure are 10 ≦ Ro ″ ≦ 100 nm, 70 ≦ Rth ″ ≦ 200 nm, average inclination The angle βo is 10 ° ≦ βo ≦ 45 °.

  Ro ″ and Rth ″ of the refractive index ellipsoid represent the in-plane slow axis of the laminated phase difference film as a, the in-plane fast axis as b, and the thickness direction axis as c in the bc plane of the laminated phase difference film. In the cross section of the refractive index ellipsoid of the laminated phase difference film, the axis that is smaller in angle with the thickness direction axis c of the laminated phase difference film out of the major axis and the minor axis of the ellipsoidal cross section is the z "axis. Of the planes perpendicular to the z ″ axis direction, the refractive index in that direction is the x ″ axis, the refractive index in that direction is nx ″, and the z ″ axis of the refractive index ellipsoid Of the planes orthogonal to the direction, the direction in which the refractive index is minimum is the y ″ axis, and the refractive index in that direction is ny ″, and is expressed as follows. The measurement wavelength is 590 nm.

  Here, βo is the longitudinal axis and in-plane of the ellipsoid in the cross section of the refractive index ellipsoid of the laminated phase difference film on the bc plane of the in-plane phase axis b and the thickness direction axis c of the laminated phase difference film. It is the average value in the thickness direction of the angle formed with the fast axis direction b.

Ro ″ = (nx ″ −ny ″) × (d1 + d2)
Rth ″ = {(nx ″ + ny ″) / 2−nz ″} × (d1 + d2)
The laminated phase difference film configuration of the present invention is the one in which the tilted phase difference film 1 that is the component is tilted and oriented, and when the tilted orientation treatment is performed, the hardness of one side and the other side of the film is It is characterized by being manufactured by performing a tilt alignment process (hereinafter also referred to as a tilt alignment process) in different states. Hardness can be represented by the elastic modulus of each surface of the retardation film when processing.

  In order to satisfy the tilt alignment treatment of the present invention, it is necessary to develop birefringence, which effectively exhibits the phase difference developability with respect to the stress applied to the film in the temperature range where the tilt alignment treatment is performed. In addition, the absolute value of the phase difference needs to be a desired value.

  In addition to the tension in the film conveying direction, the tilt orientation treatment of the present invention is characterized by changing the hardness of the film in the conveying direction. It is effective to have

  Furthermore, in the tilt orientation treatment of the film, it is preferable to keep the width by suppressing the dimensional change in the width direction of the film.

  The present invention stably and efficiently aligns the axis of the film having birefringence by performing the hardness of the film front and back, the tension in the transport direction, the high temperature gradient in the transport direction, and the width in the width direction. It is possible to incline.

Details of the present invention will be described below.
<Inclined retardation film 1>
The tilt retardation film 1 of the present invention has a wavelength dispersion L40 of 0.9 to 1.09 and an average tilt angle β of 50 ° to 85 ° observed from a direction inclined by 40 ° from the normal direction of the film surface. The refractive index ellipsoid in-plane retardation Ro ′ is 0 ≦ Ro ′ ≦ 80 nm, and the refractive index ellipsoid thickness retardation Rth ′ is −200 ≦ Rth ′ ≦ −30 nm.
<Calculation method of Ro 'of refractive index ellipsoid>
The phase difference is measured at a tilt point of −40 to 40 ° at the measurement point. In that case, the data which measured the width direction of the inclination retardation film 1 as the rotation center of measurement are taken, and the graph which plotted the phase difference (vertical axis) with respect to the inclination angle (horizontal axis) is drawn.

In the graph, the phase difference value of the tilt angle φ taking the extreme value is read, and the phase difference value becomes Ro ′ of the refractive index ellipsoid of the inclined phase difference film 1.
<Calculation method of Rth 'of refractive index ellipsoid>
In the graph that is not symmetrical about the 0 ° center (the graph measured with the width direction as the rotation center) used in the calculation of β and Ro ′, the phase difference value of φ + 40 ° or φ−40 ° is expressed as a refractive index ellipse. It is defined as R40 ′ of the body.

  Of the value of Ro ′, the value of R40 ′, the film thickness d (nm), the average refractive index value of the film, and the plane perpendicular to the z ′ direction of the refractive index ellipsoid by commercially available calculation software “N-Calc”, The refractive index (nx) in the direction (x ′) in which the refractive index is maximum, the direction (y ′) in which the refractive index is minimum among the planes orthogonal to the z ′ direction of the refractive index ellipsoid, and the thickness direction (z ′) ', Ny', nz '). From the values of nx ′, ny ′, and nz ′ obtained, the thickness direction retardation value Rth ′ of the refractive index ellipsoid was calculated according to the above formula.

Note that Ro ″ and Rth ″ of the laminated retardation film of the present invention are also calculated by the same method.
<Wavelength dispersion L40>
In the tilted retardation film 1 of the present invention, the wavelength dispersion L40 is a ratio of retardation values observed from a direction inclined by 40 ° in any direction from the normal direction of the film surface, R40 ′ (480) / R40 ′ (630). It is characterized by being. The values in parentheses represent the measurement light wavelength (nm). This value is preferably 0.95 to 1.08, more preferably 0.99 to 1.07.
<Average inclination angle β1>
In the inclined retardation film 1 of the present invention, the average inclination angle β1 is the refraction of the inclined retardation film 1 on the b′c ′ plane of the in-plane advance phase axis b ′ and the thickness direction axis c ′ of the inclined retardation film 1. It is the average value in the thickness direction of the angle formed by the long axis of the ellipsoid and the in-plane fast axis b ′ in the cross section of the elliptical ellipsoid.

  In the present invention, β1 is 50 ° ≦ β1 ≦ 85 °, and preferably 55 ° ≦ β1 ≦ 70 °.

  β1 is a measurement wavelength of 590 nm with respect to the film surface, measurement spot diameter: 100 μm or less (preferably 20, 25 μm), measurement pitch: 0.5 mm, measurement point: width direction (TD direction) at the same position, Measure 500 points in the transport direction (MD direction), and tilt at −40 to 40 ° in 5 ° increments with the in-film slow axis and in-film fast axis as the tilt axes at each spot. Measure the phase difference at the angle.

Take two pieces of data, and read the value of the abscissa of the graph that is asymmetric about 0 ° (with β2),
i) When the graph is convex upward: the difference between that value and 90 ° (β1 = 90 ° −β2) is β1.
ii) When the graph is convex downward: β2 = β1.
<Phase difference (retardation) Ro ', Rth'>
Ro ′ of the tilted retardation film 1 of the present invention is 0 ≦ Ro ′ ≦ 80 nm, preferably 10 ≦ Ro ′ ≦ 70 nm. Rth ′ is −200 ≦ Rth ′ ≦ −30 nm, and preferably −100 ≦ Rth ′ ≦ −40 nm.

Ro ′ and Rth ′ can be measured using an automatic birefringence meter. At that time, in an environment of 23 ° C. and 55% RH, the measurement wavelength is 590 nm with respect to the film surface, the measurement spot diameter is 100 μm or less, the measurement pitch is 0.5 mm, and the measurement point is the same position as the width. It is preferable to use an apparatus capable of measuring θ under the condition of 500 points in the direction and measuring the birefringence and retardation value. For example, there is a micro-region birefringence measuring device manufactured by Mizoji Optical Industry Co., Ltd.
<Inclined retardation film 1 material>
The tilted phase difference film 1 is made of a material having negative intrinsic birefringence.

  As the resin having a negative intrinsic birefringence, a resin that has a negative intrinsic birefringence and can be extruded into a film can be used.

  Examples of the resin having a negative intrinsic birefringence include a polystyrene resin, a resin made of a copolymer of a styrene derivative and a maleimide derivative (for example, a copolymer of styrene and N-phenylmaleimide), a styrene derivative and an acrylic acid derivative ( Examples thereof include vinyl resins such as a resin made of a copolymer of styrene and acrylic acid) and an acrylic acid ester polymer (for example, polymethyl methacrylate).

  Specifically, a copolymer of a styrene derivative is preferable. Examples of styrene derivatives include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, p-trifluoromethylstyrene, p-methoxystyrene, p-hydroxystyrene, p-chlorostyrene, p-nitrostyrene, p -Aminostyrene, p-carboxystyrene, p-phenylstyrene, p-tertbutoxystyrene, 2,4,6-trimethylstyrene and the like. Any of these monomers may be used alone, or two or more of these monomers may be used in combination. Of these monomers, styrene, α-methylstyrene, and p-hydroxystyrene are preferably used alone / in combination.

  Examples of maleimide derivatives include N-substituted maleimides such as maleic anhydride, maleimide and N-phenylmaleimide, maleic acid and derivatives thereof, fumaric acid and derivatives thereof, and the like. Any of these monomers may be used alone, or two or more of these monomers may be used in combination. Of these monomers, maleic anhydride and N-phenylmaleimide are preferably used in terms of heat resistance and adhesion to the cyclic olefin resin layer.

  Acrylic acid esters include methacrylic acid esters such as (meth) acrylic acid, (meth) acrylic acid alkyl esters such as methyl (meth) acrylate, and (meth) acrylic acid amides. Any of these monomers may be used alone, or two or more of these monomers may be used in combination.

  Among these materials having negative intrinsic birefringence, a methyl methacrylate-styrene copolymer is preferable. In the present invention, TX-320XL (MS resin manufactured by Denki Kagaku Kogyo Co., Ltd.) was used.

  As a polymerization method, a known method can be appropriately employed. The weight average molecular weight can be appropriately selected from 10,000 to 1,000,000. The average molecular weight is based on GPC in terms of polystyrene.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used.

As the resin of the present invention, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), TX-100S, 400S, KT75 (Electricity) Chemical Industry Co., Ltd.), Sebian-MAS series (Daicel Polymer Co., Ltd.), Estyrene MS Series (manufactured by Nippon Steel Chemical Co., Ltd.), Dairaku D332, Dairaku D232 (manufactured by Nova Chemicals Co., Ltd.), Rurex Commercially available resins such as A14, Lurex A15 (manufactured by DIC Corporation), and PN-177 (manufactured by CHIMEI Corporation) can also be preferably used as the vinyl resin of the present invention.
<Other constituent materials of the inclined retardation film 1>
(Phase difference, wavelength dispersion adjusting agent)
Specific examples of the retardation and wavelength dispersion adjusting agent preferably used in the present invention include compounds described in JP-A No. 2005-99191 and JP-A No. 2008-64941, for example, benzotriazole compounds, benzophenone compounds, Examples include triazine compounds, cyanoacrylate compounds, salicylic acid ester compounds, nickel complex compounds, and the like, but the present invention is not limited to these compounds.

(Other additives)
The gradient retardation film 1 of the present invention contains general additives such as ultraviolet absorbers, antioxidants and fine particles as described in Table 1 of JP-A-2008-64941. Can do.
<The manufacturing method of the inclination retardation film 1>
<Adjustment of front and back elastic modulus>
The retardation film of the present invention is a production method that preferably has a difference in hardness between the front and back surfaces, specifically, the elastic modulus during the tilt orientation treatment. Specific methods include a method of creating a temperature difference between the front and back of the film during the tilt orientation treatment, a method of laminating films having different elastic moduli, and a method of adjusting the amount of residual solvent when forming a film by solution casting. Etc.

  As a method of laminating films having different elastic moduli, a method of laminating layers with different resins, additives, etc. can be selected. Lamination methods include co-casting, co-extrusion, double casting, bonding, etc. This method can be used. When laminating with the retardation film 2 later, the inclined retardation film 1 from which the layers having different elastic moduli are peeled may be laminated on the retardation film 2 or may be laminated on the retardation film 2 without peeling. Also good.

  Moreover, a good solvent can be apply | coated and the film surface can be dissolved and bonded, and it can also bond in the residual solvent state at the time of film forming of retardation film. Moreover, the coating liquid containing resin and an additive can also be coated on the single side | surface or both surfaces of the already formed film.

  When using these means, the adhesive layer at the interface between the films is preferably as thin as possible. For example, any of the adhesive layers formed by the above means is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less.

    In the present invention, when the difference in elastic modulus between the front and back surfaces necessary for the tilt alignment treatment is provided by lamination, the difference in elastic modulus can be substantially provided by utilizing the difference in glass transition temperature. In that case, it is preferable to laminate two or more layers having a glass transition temperature difference of 5 ° C. or more, preferably 20 ° C. or more and 150 ° C. or less.

  For the glass transition point, the DSC method (JIS C 6481) is used to raise the temperature of the test piece from room temperature at a rate of 20 ° C./min, the calorific value is measured with a differential scanning calorimeter, and the endothermic curve obtained as a result. Two extension lines are drawn on the (exothermic curve), and Tg is obtained from the intersection of the 1/2 straight line between the extension lines and the endothermic curve.

  In the case of carrying out with a single film, a method based on the temperature difference between the front and back of the film during the tilt orientation treatment and a method of adjusting the amount of residual solvent when the solution is cast into a film can be employed. A temperature difference can be made by applying winds with different temperatures on the front and back of the film or bringing rolls with different temperatures into contact with each other. The temperature difference between the front and back of the film is preferably in the range of 20 to 150 ° C.

  In the case of the solution casting film forming method, in addition to the method of changing the residual solvent amount by changing the drying speed of the front and back of the film, use the method of changing the plasticizer content in the thickness direction by controlling the drying speed You can also.

  The residual solvent amount difference between the front and back of the film is preferably in the range of 1 to 150% by mass. As means for controlling the difference in residual solvent amount, there are means for changing the temperature and air volume of the drying air on the front and back, or laminating components having different solvent amounts.

  In addition, a coating solution containing a resin and an additive can be coated on one side or both sides of a film that has already been formed, or a plurality of solutions containing resins and additives with different amounts of solvent can be used for double casting or co-casting. There is also means for laminating by a casting film forming method.

  The amount of residual solvent on the front and back sides is the same as the amount of residual solvent in each single layer in the case of a laminate, and the drying conditions for each condition in the front and back sides are fixed to the respective conditions. And measure the amount of residual solvent.

  The amount of residual solvent is defined as follows.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass at the time of starting the inclined alignment treatment of the web, and N is the mass when the mass M is dried at 110 ° C. for 3 hours.

The elastic modulus adjusted by the above method can be measured by the following method. In addition, the elasticity modulus in this invention means a tensile elasticity modulus.
1) Method of making temperature difference between film front and back Measure the elastic modulus of the original film. First, Tg is measured by DSC, and then the elastic modulus is calculated by the same method as 1) at (Tg + 5) ° C. and (Tg−30) ° C.
2) A method of changing the amount of residual solvent by changing the drying speed of the front and back of the film. Next, sample 2 is produced by drying both surfaces of the film under the drying conditions from the back side of the film. The Tg1 and Tg2 of each of the samples 1 and 2 (Tg1> Tg2) are measured by DSC. The elastic modulus of each film is calculated in the same manner as in 1) at a temperature of (Tg2 + 5) ° C.
3) Method of laminating films having different elastic moduli The glass transition temperatures of the single-layer film for each of the first and second layers are measured to obtain Tg1 and Tg2 (Tg1> Tg2). The sample was allowed to stand for 24 hours or more under the conditions of 23 ° C. and 50 ± 5% RH, and then cut into a width of 10 mm × a length of 200 mm so that the film transport direction (running direction = longitudinal direction) would be the longitudinal direction (Tg2 + 5 ) Set each sample at a temperature of 0 ° C., chucking pressure: 0.25 MPa, distance between marked lines: 100 ± 10 mm, and pull at a pulling speed of 100 ± 10 mm / min.

  From the obtained tensile stress-strain curve, the elastic modulus calculation start point is 10 N, the end point is 30 N, and the tangent line drawn between them is extrapolated to calculate the elastic modulus of each film.

<Original film>
In the present invention, the film immediately before the tilt alignment treatment is called a raw film.

The raw film for producing the inclined retardation film 1 of the present invention may be a laminate of a plurality of films, and the laminate may be bonded using a substrate-less adhesive film.
(Application and lamination of multiple optical layers)
The raw film for producing the retardation film of the present invention may be a laminate of a plurality of optical layers, and there is a method of applying a coating solution for the optical layer to a support film. As a method of coating the coating solution, spin coating method, roll coating method, printing method, dip pulling method, die coating method, casting method, bar coating method, blade coating method, spray coating method, gravure coating method, reverse coating method Ink jet method or extrusion coating method.

  Alternatively, the film may be saponified and bonded using polyvinyl alcohol. Moreover, a good solvent may be apply | coated and the film surface may be dissolved and bonded, and you may bond in the residual solvent state at the time of film forming of retardation film.

When using these bonding means, the adhesive layer at the interface between the film and the film is preferably as thin as possible. For example, any of the adhesive layers formed by the above means is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. Further, as described in paragraph (0246) of JP2009-25604A, the adhesive layer can be applied without saponification treatment by atmospheric pressure plasma treatment.
<Phase difference of the raw film>
The retardation of the raw film of the present invention is, for example, a refractive index ellipsoidal film satisfying 0 ≦ Ro ≦ 100 nm and 0 ≦ Rth ≦ 180 nm. By performing, the inclined retardation film 1 in which the refractive index ellipsoid of the retardation plate is inclined with respect to the film surface of the retardation plate can be obtained.

<Phase difference expression>
The retardation expression of the present invention refers to the degree of retardation that can be expressed with a thickness per 1 μm of the tilted retardation film, and is in the range of 0.3 to 20 nm / μm, and 0.5 to 5 nm / μm. Is preferred.

  The expression of the phase difference can be achieved by applying a force (for example, simple film formation, stretching treatment, conveyance tension, etc.) to the material forming the raw film.

  You may improve retardation development with an additive.

  For example, the retardation development property can be improved by adding a retardation increasing agent described in JP-A Nos. 2000-1111914 and 2002-62430. Or it is also possible to give high phase difference expression property by making process temperature low within a predetermined range. Furthermore, the phase difference can be controlled by the post-stretching temperature. In this case, the phase difference can be increased by lowering the temperature.

  The phase difference developability can be measured by the following method.

  In the case where the raw film is a laminated film, the single layer films are respectively produced.

  Each Tg is measured by DSC, and the film having the lower Tg is determined as film A. In an environment of 23 ° C. and 55% RH, the film A is allowed to stand for 24 hours, and Ro at a measurement wavelength of 590 nm is measured as Ro (1). Further, the film thickness is measured and set to d (1).

  Using a tensile tester (TG-2KN, manufactured by Minebea Co., Ltd.), the above samples were set at a chucking pressure of 0.25 MPa and a distance between marked lines of 100 ± 10 mm, and the film temperature (Tg ± 5) ° C. Under the condition of 50 ± 5% RH, the film was stretched at a stretching ratio of 1.4 times in the longitudinal direction at a pulling speed of 100 ± 10 mm / min, and the film thickness d (2) and Ro (2) of the sample was stretched. Measure.

  In addition, what added the absolute value of the dimensional change rate of the direction orthogonal to the direction of extending | stretching the dimensional change rate of a film direction and a film center part is defined as an actual draw ratio, and an actual draw ratio will be 1.4 times. Adjust as follows.

  And it defines as phase difference expression property = Ro (2) / d (2) -Ro (1) / d (1).

<Inclined orientation treatment>
The tilted retardation film 1 of the present invention can be produced by subjecting the raw film to a tilt orientation treatment.

  The inclined alignment processing apparatus has a preheating zone, an inclined alignment zone, and a cooling zone as basic zones (processes) (FIG. 4).

  In the present invention, it is possible to obtain the inclined retardation film 1 of the present invention simply by passing the preheating zone, the inclined orientation zone, and the cooling zone while applying tension in the transport direction and maintaining the widthwise dimension. Features.

  The preheating zone of the present invention is a zone for preheating a raw film, and is a zone for heating the temperature of the film to a set temperature that is equal to or lower than the set temperature T2 ° C. of the inclined alignment zone. In the preheating zone, the maximum temperature in the preheating zone is adjusted near the exit of the zone. The maximum temperature varies depending on the material of the original film that is tilted and oriented, but is preferably (Tg + 30) ° C. or lower of the original film. The preheating zone preferably passes in 0.5 to 10 seconds.

  The inclined orientation zone of the present invention is a zone for actually orienting the original film. By providing the temperature gradient of the present invention in this zone, the retardation of the raw film can be inclined.

  The cooling zone of the present invention is for fixing the tilted orientation state in the tilted orientation zone and controlling the tension of the film. The temperature in the cooling zone is T2-5 ° C. or lower, more preferably Tg or lower, when the set temperature of the inclined alignment treatment zone is T2 ° C.

In the present invention, the temperature gradient in the tilted alignment zone is as defined below.
1) In the case of temperature increase: non-contact type radiation at a position 50 cm from the end point of the preheating zone, every 50 cm from the start point to the end point of the inclined alignment treatment zone, and every 50 cm from the start point to the end point of the cooling zone Install a thermometer and measure the surface temperature on both sides of the film.

  The film set temperature at the end point of the preheating zone is T1 ° C. Further, the film setting temperature in the inclined alignment treatment zone is T2 ° C., and the time from T1 ° C. to T2 ° C. is t1 seconds. Then, (T2−T1) / t1 [° C./second] is defined as a temperature gradient in the case of a temperature rise. T1 and T2 are temperatures set appropriately from Tg1 and Tg2.

Here, the film set temperature refers to a film surface temperature set in advance so as to be the temperature. The film surface temperature is the surface temperature of the lower elastic modulus.
2) In the case of temperature drop: The film set temperature at the end point of the inclined orientation treatment zone is the same as T2. The film set temperature in the cooling zone is T3 ° C., and the time from T2 to T3 ° C. is t2 seconds. Then, (T3−T2) / t2 [° C./second] is defined as a temperature gradient in the case of a temperature decrease.

  Further, (T3−T1) ° C. is defined as a temperature difference between the entry side and the exit side.

  The temperature gradient of the present invention is 20 ° C./second to 500 ° C./second in the case of a temperature rise, and −20 ° C./second to −500 ° C./second in the case of a fall. Preferably, the temperature is 20 ° C./sec to 250 ° C./sec in the case of temperature rise. More preferably, it is 20 degreeC / second-100 degreeC / second. In the case of a temperature decrease, it is −20 ° C./second to −250 ° C./second. More preferably, it is −20 ° C./further −100 ° C./second.

  The tilted alignment zone is preferably passed for 0.01 to 10 seconds, more preferably 0.5 to 10 seconds.

  In the tilt alignment treatment step, it is preferable to apply tension to the film conveyance direction (MD direction) and to regulate the width in the width direction (TD direction).

  In the manufacturing apparatus of the present invention, there is a means for partitioning between adjacent zones using a wind shield, and the wind shield may be partitioned with a gap left. Moreover, it is also preferable to nip and partition with a roll. As a means for partitioning adjacent zones, a preferred form is a form of partitioning with a wind shield plate, but it is possible to partition using both a wind shield plate and a roll, or partition with a roll alone.

  The temperature can be controlled by installing a thermometer (for example, a non-contact thermometer) capable of online measurement display in each partitioned zone.

  As a heating / cooling method for each zone, there are a method of changing the temperature and air volume of the wind, and a method of using a heat roll and a cooling roll. In the present invention, a known method can be used.

  The method of using a roll tends to have a higher effect of improving the front contrast as compared with the case of using only wind. Although the cause of this is not well understood, it is estimated that the roll can be heated or lowered more efficiently than the temperature control by wind, so the uniformity of the film is improved and the generation of minute haze is suppressed. .

(Tension in the transport direction)
In order to perform the tilt alignment treatment of the present invention, it is necessary to apply a tension in the MD direction. However, if the tension is excessively increased, the film is stretched in the long direction and the tilt angle becomes small. Therefore, it is preferable to adjust the conveyance tension so that the dimensional change in the longitudinal direction is within 5% (0.95 to 1.05 times) before entering the inclined alignment processing apparatus and after leaving. .

  As a tension control means, there is a means for controlling the tension by providing two or more pairs of nip rolls in the vicinity of the inlet of the preheating zone and the outlet of the cooling zone with the preheating zone, the inclined orientation zone, and the cooling zone in between (see FIG. 4). . It is also preferable to provide a spare nip roll in the preheating zone. Tension can be applied while transporting with a tenter. Alternatively, the tension can be controlled by compressing with a pair of nip rolls. In that case, the roll is preferably made of rubber.

  There is also a means for applying tension to the film by utilizing the shrinkage and expansion of the film used in the present invention. In that case, tension in the transport direction may be applied by a tenter as long as it is a means that facilitates displacement in the transport direction.

(Width direction regulation)
In the tilted orientation zone of the present invention, it is necessary to regulate the width of the film in the width direction, and the degree of change should be within -5% (0.95 to 1.05 times the dimensional change). preferable.

  By setting this range, the uniformity of the tilt angle can be improved, and the uniformity can be improved in the tilt direction as well as in the in-plane axial direction. It is presumed that by causing shrinkage in the width direction, there is a place where the contraction stress applied in the width direction is released, so that the uniformity is impaired.

  Examples of the film width dimension regulating method in the present invention include a tenter and a roll. In the case of regulating the width with a tenter, there is a method of performing desired processing while holding both ends of the obtained raw film with clips and transporting it with a tenter while maintaining the width.

  When the width is restricted with a roll, a desired process is performed while one or both sides of the film are in contact with the roll. As the material of the roll, metal, rubber, or the like can be used, but it is preferable that the frictional force in the width direction is as large as possible.

(Stretching process)
In the present invention, a stretching step may be provided either before or after the tilt alignment treatment. This stretching process is exclusively for stretching in the TD direction and is provided for adjusting the phase difference (Ro, Rth) as the tilted phase difference film 1, but the tilted phase difference film 1 is stretched. Instead, the retardation of the final laminated retardation film may be adjusted by laminating the retardation film 2.

The draw ratio is 1.06 to 1.30 times, preferably 1.06 to 1.15 times. The stretching treatment is preferably performed within a range that does not affect the tilt alignment treatment.
<Other optical properties>
(Haze)
Haze measures haze according to JIS-K7136 using Nippon Denshoku Co., Ltd. haze meter NDH2000. The smaller the haze, the better the display quality of the liquid crystal display device, particularly the front CR. The haze value of the retardation film of the present invention is not particularly limited, but is preferably 0.1% or less, more preferably 0.05% or less.

  The raw film of the retardation film used in the present invention can be preferably used regardless of whether it is a film produced by a normal solution casting method or a film produced by a melt casting method.

The thickness of the gradient retardation film 1 of the present invention is in the range of 5 to 500 μm, preferably in the range of 10 to 200 μm, and particularly preferably in the range of 15 to 150 μm.
<Other functional layers>
The gradient retardation film 1 of the present invention can be provided with a back coat layer, a hard coat layer, and an antireflection layer as described in JP-A-10-319536 and JP-A-2007-159330, if necessary.
<Phase difference film 2>
The retardation film 2 of the present invention has a biaxial position characterized by 10 ≦ Ro ≦ 100 nm, 20 ≦ Rth ≦ 230 nm and the in-plane retardation wavelength dispersion L is 0.9 or more and less than 1.0. It is a phase difference film.

Ro = (nx + ny) / 2 × d2
Rth = {(nx + ny) / 2−nz} × d2
Here, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the retardation film 2, and ny is in the direction y orthogonal to the direction x in the in-plane direction of the retardation film 2. The refractive index is represented, nz represents the refractive index in the thickness direction z of the retardation film 2, and d2 (nm) represents the thickness of the retardation film 2.

  The retardation film 2 of the present invention is preferably a film obtained by adding sugar ester compound C and polyester D to cellulose ester.

<Cellulose ester>
The cellulose ester used in the retardation film 2 of the present invention is a carboxylic acid ester having about 2 to 22 carbon atoms, and may be an aromatic carboxylic acid ester, particularly a lower fatty acid ester having 6 or less carbon atoms. Is preferred.

  The acyl group bonded to the hydroxyl group may be linear or branched or may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms is large, and therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose ester preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  Specifically, the cellulose ester includes cellulose acetate propionate, cellulose acetate butyrate, or a mixed fatty acid ester of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate butyrate. Can be used.

  The butyryl group forming butyrate may be linear or branched. As the cellulose ester preferably used in the present invention, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate phthalate are particularly preferably used.

  Preferred cellulose esters other than cellulose acetate phthalate for the present invention preferably satisfy the following formulas (1) and (2).

Formula (1) 2.0 <= X + Y <= 3.0
Formula (2) 0 ≦ Y ≦ 1.5
In the formula, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or butyryl group, or a mixture thereof.

  Of these, cellulose acetate propionate is particularly preferably used. In cellulose acetate propionate, 1.0 ≦ X ≦ 2.5, preferably 0.1 ≦ Y ≦ 1.5, and 2.0 ≦ X + Y ≦ 3.0. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The number average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000 because the mechanical strength of the resulting film is strong. Furthermore, the thing of 70000-200000 is used preferably.

  The weight average molecular weight Mw and number average molecular weight Mn of the cellulose ester were measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

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

  The cellulose used as a raw material of the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

  The cellulose ester such as cellulose acetate phthalate of the present invention can be produced by a known method. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

<Sugar ester compound C>
The retardation film 2 of the present invention contains an ester compound C in which at least one of a pyranose structure or a furanose structure is 1 or more and 12 or less and all or part of the OH groups of the structure are esterified. preferable.

  The proportion of esterification is preferably 60% or more, more preferably 75% or more of the OH group present in the pyranose structure or furanose structure.

  Examples of sugars preferably used in the present invention include the following, but the present invention is not limited to these.

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

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

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

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

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

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

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

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

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

The sugar ester compound of the present invention is a compound obtained by condensing 1 or more and 12 or less of at least one pyranose structure or furanose structure represented by the following general formula (A). However, R < ₁₁ > -R < ₁₅ >, R < ₂₁ > -R < ₂₅ > represents a C2-C22 acyl group or a hydrogen atom, m and n represent the integer of 0-12 respectively, and m + n represents the integer of 1-12.

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

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

<Polyester D>
The retardation film 2 of the present invention preferably contains the polyester D represented by the general formula (1).
General formula (1) B- (GA) n-GB
(In the formula, B is an arylcarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A Represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (1), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the arylcarboxylic acid component of the polyester D used in the present invention include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, There are aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of polyester D that can be preferably used for the retardation film 2 used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2 -Butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1, 3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3) 3-dimethylolheptane), 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2 4-trimethyl 1,3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol These glycols are used as one or a mixture of two or more.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  In addition, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The polyester D used for the retardation film 2 has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

  Although the specific compound of the aromatic terminal ester plasticizer of the structure shown to the general formula (c) which can be used for this invention below is shown, this invention is not limited to this.

<Other additives>
(Plasticizer)
The retardation film 2 of the present invention includes a phosphate ester plasticizer, a phthalate ester plasticizer, a trimellitic acid ester plasticizer, a pyromellitic acid plasticizer, a glycolate plasticizer, and a citrate ester plasticizer. Agents, polyester plasticizers, and plasticizers of phosphate ester plasticizers can also be preferably used.

  Examples of other carboxylic acid esters include trimethylolpropane tribenzoate, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. As the polyester plasticizer, a copolymer of a dibasic acid and a glycol such as an aliphatic dibasic acid, an alicyclic dibasic acid, or an aromatic dibasic acid can be used.

  The aliphatic dibasic acid is not particularly limited, and adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyl dicarboxylic acid, and the like can be used. As glycol, ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol and the like can be used.

  These dibasic acids and glycols may be used alone or in combination of two or more.

  The amount of these plasticizers used is preferably 1% by mass to 20% by mass and particularly preferably 3% by mass to 13% by mass with respect to the cellulose ester in terms of film performance, processability and the like.

(Metal salt)
Such a cellulose acetate usually has a heat resistance stabilizer such as an alkali metal (lithium, potassium, sodium, etc.) or a salt or compound thereof, an alkaline earth metal (calcium, magnesium, strontium, Barium etc.) or a salt thereof or a compound thereof. The alkaline earth metal such as calcium contained in normal cellulose acetate is about 30 to 200 ppm per gram of cellulose acetate.

In addition, content of the metal salt in a cellulose acetate can be quantified with the following method.
<Measurement of metal salt (calcium) content>
(Pretreatment and measurement)
About 500 mg of the sample is cut, put into a decomposition tube of a sealed microwave sample decomposition apparatus, 8 ml of nitric acid (ultra high purity reagent) manufactured by Kanto Chemical Co., Ltd. is added, a wet decomposed sample is prepared, and the sample is transferred to a polypropylene container Then, it can be finished to 50 ml with ultrapure water, and Ca can be quantified with an inductively coupled plasma emission spectrometer (ICP-AES).

(Usage equipment and conditions)
Decomposition Equipment Milestone General Co., Ltd. ETHOS-1
SII Nano Technology Co., Ltd. SPS3520UV
Measurement wavelength 3933.4769nm
Calibration curve reagent Kanto Chemical Co., Ltd. Calcium standard solution for chemical analysis (UV absorber)
For the retardation film 2 of the present invention, an ultraviolet absorber is preferably used. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little 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 the ultraviolet absorber preferably used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. However, it is not limited to these.

  As the ultraviolet absorber preferably used in the present invention, a benzotriazole-based ultraviolet absorber and a benzophenone-based ultraviolet absorber that are highly transparent and excellent in preventing the deterioration of the polarizing plate and the liquid crystal are preferable, and unnecessary coloring is less. A benzotriazole-based ultraviolet absorber is particularly preferably used.

  Moreover, the ultraviolet absorber whose distribution coefficient described in Unexamined-Japanese-Patent No. 2001-187825 is 9.2 or more improves the surface quality of a long film, and is excellent also in applicability | paintability. In particular, it is preferable to use an ultraviolet absorber having a distribution coefficient of 10.1 or more.

  Further, the polymer ultraviolet absorber described in the general formula (1) or general formula (2) described in JP-A-6-148430 and the general formulas (3), (6), and (7) described in Japanese Patent Application No. 2000-156039 (Or UV-absorbing polymer) is also preferably used. As a polymer ultraviolet absorber, PUVA-30M (manufactured by Otsuka Chemical Co., Ltd.) and the like are commercially available.

(Fine particles)
In order to impart slipperiness to the retardation film 2 of the present invention, it is preferable to add fine particles.

  The primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm.

  These fine particles preferably form secondary particles having a particle diameter of 0.1 to 5 μm and are contained in the retardation film 2. The preferable average particle diameter is 0.1 to 2 μm, and more preferably 0.2. ~ 0.6 μm. Thereby, the unevenness | corrugation about 0.1-1.0 micrometer high can be formed in the film surface, and this can give appropriate slipperiness to the film surface.

  The primary average particle diameter of the fine particles used in the present invention is measured by observing the particles with a transmission electron microscope (magnification 500,000 to 2,000,000 times), observing 100 particles, measuring the particle diameter, and measuring the average. The value was taken as the primary average particle size.

  The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter. A larger apparent specific gravity makes it possible to make a high-concentration dispersion, which improves haze and agglomerates, and is preferable when preparing a dope having a high solid content concentration as in the present invention. Are particularly preferably used.

  Silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, a mixture of vaporized silicon tetrachloride and hydrogen burned in air at 1000 to 1200 ° C. Can be obtained. For example, it is marketed with the brand name of Aerosil 200V and Aerosil R972V (above, Nippon Aerosil Co., Ltd. product), and can use them.

The apparent specific gravity described above is calculated by the following equation by taking a certain amount of silicon dioxide fine particles in a graduated cylinder, measuring the weight at this time.
Apparent specific gravity (g / liter) = silicon dioxide mass (g) / volume of silicon dioxide (liter)
<Method for producing retardation film 2>
Next, the manufacturing method of the retardation film 2 of this invention is demonstrated in detail.

  The retardation film 2 of the present invention can be preferably used regardless of whether it is a film produced by a solution casting method or a film produced by a melt casting method.

  Production of the retardation film 2 of the present invention includes a step of preparing a dope by dissolving cellulose acetate and an additive in a solvent, a step of casting a dope on an endless metal support, and a cast dope. Is performed by a step of drying as a web, a step of peeling from a metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished film.

  The process for preparing the dope will be described. The concentration of cellulose acetate in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose acetate is too high, the load during filtration increases and the filtration accuracy is poor. Become. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used in the dope may be used alone or in combination of two or more. However, it is preferable to use a mixture of a good solvent and a poor solvent of cellulose acetate in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of solubility of cellulose acetate.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose acetate to be used independently is defined as a good solvent, and what does not swell or dissolve independently is defined as a poor solvent.

  Therefore, in general, depending on the average acetylation degree (acetyl group substitution degree) of cellulose acetate, the good solvent and the poor solvent change. For example, when acetone is used as a solvent, cellulose acetate (acetyl group substitution degree 2.4) It becomes a good solvent, and cellulose acetate (acetyl group substitution degree 2.9) becomes a poor solvent.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope.

  Moreover, the solvent used for melt | dissolution of a cellulose acetate collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again.

  The recovery solvent may contain trace amounts of additives added to cellulose acetate, such as plasticizers, UV absorbers, polymers, monomer components, etc., but these are preferably reused even if they are included. Can be purified and reused if necessary.

  As a method for dissolving cellulose acetate when preparing the dope described above, a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure.

  It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos.

  A method in which a cellulose ester is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.

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

  The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates.

  A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  Alternatively, a cooling dissolution method is also preferably used, whereby cellulose acetate can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose acetate solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small.

  For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable.

  It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose acetate by filtration.

A bright spot foreign material is arranged with two polarizing plates placed in a crossed Nicol state, a retardation film 2 or the like is placed between them, light is applied from one polarizing plate, and observation is performed from the other polarizing plate. It is a point (foreign matter) where light from the opposite side appears to leak, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less.

More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / m < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable.

  A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

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

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface. As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used.

  The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate.

  The preferred support temperature is 0-60 ° C, more preferably 25-55 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

  In order for the cellulose ester film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

  In the present invention, the amount of residual solvent is defined by the following formula.

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

  Further, in the drying step of the cellulose ester film, the web is peeled off from the metal support, and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, Especially preferably, it is 0-0.01 mass%.

  In the film drying step, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

  In order to produce the retardation film 2 of the present invention, it is particularly preferable to stretch in the width direction (lateral direction) by a tenter method in which both ends of the web are gripped by clips or the like. Peeling is preferably performed at a peeling tension of 300 N / m or less.

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

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

  The retardation film 2 of the present invention preferably has a width of 1 to 4 m. In particular, those having a width of 1.3 to 4 m are preferably used, and particularly preferably 1.3 to 3 m.

  Retardation values Ro and Rth targeted by the retardation film 2 of the present invention can be adjusted by the amount of sugar ester C and polyester D to be added and the stretching ratio (control of tenter stretching and transport tension) during film production. it can.

  Biaxial stretching or uniaxial stretching can be performed sequentially or simultaneously with respect to the longitudinal direction (film forming direction) of the film and the direction orthogonal to the longitudinal direction of the film, that is, the width direction.

  The draw ratios in the biaxial directions perpendicular to each other are preferably in the range of 0.8 to 1.5 times in the casting direction and 1.1 to 2.5 times in the width direction, respectively. It is preferable to carry out in the range of 0.8 to 1.0 times in the direction and 1.3 to 1.5 times in the width direction.

  The stretching temperature is preferably 120 ° C. to 200 ° C., more preferably 140 ° C. to 200 ° C., more preferably 140 ° C. to 180 ° C. or less.

  The residual solvent in the film is preferably 20 to 0%, more preferably 15 to 5%.

  There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction between the rolls. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination.

  In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

  These width maintenance or lateral stretching in the film forming step is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

  When the slow axis or the fast axis of the retardation film 2 of the present invention is present in the film plane and the angle formed with the film forming direction is θ3, θ3 is preferably −1 ° or more and + 1 ° or less, − More preferably, it is 0.3 ° or more and + 0.3 ° or less.

This θ3 can be defined as an orientation angle, and θ3 can be measured in an atmosphere of 23 ° C. and 55% RH using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). Each of θ3 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and can contribute to obtaining faithful color reproduction in a color liquid crystal display device.
<Liquid crystal display device>
By using the tilted phase difference film 1 and the phase difference film 2 of the present invention in a TN type liquid crystal display device, the TN type liquid crystal display device of the present invention excellent in viewing angle and color shift from an oblique direction can be produced.

  The inclined retardation film 1 and the retardation film 2 of the present invention preferably have a laminated retardation film configuration.

The liquid crystal display device has a configuration in which the liquid crystal cell is sandwiched between two polarizing plates arranged in crossed Nicols, but the laminated retardation film configuration of the present invention is arranged on the liquid crystal cell side with respect to the polarizer of the polarizing plate. The
<Laminated retardation film configuration>
As a method of laminating the inclined retardation film 1 and the retardation film 2 of the present invention, a method of laminating only the inclined retardation films 1 and 2 with an adhesive, it became a part of a polarizing plate as a polarizing plate protective film. The method etc. which bond the inclination retardation film 1 to the retardation film 2 with an adhesive are mentioned.

In addition, it can also laminate | stack by the extrusion method after the inclination orientation process of the inclination retardation film 1. FIG.
<Laminated retardation film>
The laminated retardation film structure of the present invention is such that Ro ″, Rth ″ of the refractive index ellipsoid of the laminated retardation film is 10 ≦ Ro ″ ≦ 100 nm, 70 ≦ Rth ″ ≦ 200 nm, and the average inclination angle βo is 10 ≦ βo ≦. It is characterized by 45 °.

  Here, when the in-plane slow axis of the laminated retardation film is a, the in-plane fast axis is b, and the thickness direction axis is c, the average inclination angle βo is the in-plane fast axis of the laminated retardation film. This is the average value in the thickness direction of the angle formed by the major axis of the ellipsoid and the in-plane fast axis b in the cross section of the refractive index ellipsoid of the laminated retardation film on the bc plane of the thickness direction axis c. . It is preferable that a is a ', b is b' and c is the same axis as c '.

  In the cross section of the refractive index ellipsoid of the laminated phase difference film in the bc plane of the laminated phase difference film, Ro ″ and Rth ″ of the refractive index ellipsoid are the laminating positions of the major axis and the short axis of the ellipsoidal cross section. The axis with the smaller angle formed with the thickness direction c of the retardation film is defined as the z ″ axis, the refractive index in that direction is nz ″, and the direction in which the refractive index is maximum among the planes orthogonal to the z ″ axis direction is x ″. The axis, the refractive index in that direction is nx ″, the direction in which the refractive index is minimum among the planes orthogonal to the z ″ axis direction of the refractive index ellipsoid is the y ″ axis, and the refractive index in that direction is ny ″. It expresses like this. The measurement wavelength is 590 nm.

Ro ″ = (nx ″ + ny ″) / 2 × (d1 + d2)
Rth ″ = {(nx ″ + ny ″) / 2−nz ″} × (d1 + d2)
Preferably, Ro ″ is 20 nm to 60 nm, Rth ″ is 90 nm to 160 nm, and βo is 15 ° to 30 °.

Ro ″, Rth ″ and βo of the laminated retardation film of the present invention can be measured in the same manner as the inclined retardation film 1.
<Polarizing plate>
The polarizing plate which used the retardation film 2 of this invention as the polarizing plate protective film, and it can be used for the liquid crystal display device of this invention using it.

  A general polarizing plate has a configuration in which a polarizer obtained by stretching polyvinyl alcohol is sandwiched between two polarizing plate protective films, and the retardation film 2 of the present invention can be used as one of the polarizing plate protective films. it can.

  The polarizing plate of the present invention can be produced by a general method.

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

  For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound. The film thickness of the polarizer is preferably 5 to 30 μm, particularly preferably 10 to 20 μm.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol%. Ethylene-modified polyvinyl alcohol is also preferably used.

  Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used.

  Specifically, for example, a PVA adhesive is preferable from the viewpoint of the stability of the adhesive treatment. These adhesives and pressure-sensitive adhesives may be applied to the surface of the polarizer or the transparent protective layer as they are, for example, or a layer such as a tape or sheet composed of the adhesive or pressure-sensitive adhesive is disposed on the surface. May be. For example, when prepared as an aqueous solution, other additives and catalysts such as acids may be blended as necessary. In the aqueous solution, for example, other additives and a catalyst such as an acid can be blended as necessary. Among these, as the adhesive, a PVA adhesive is preferable from the viewpoint of excellent adhesiveness with a PVA film.

  In the cellulose ester film, the polarizer side is preferably bonded to at least one surface of a polarizer prepared by alkali saponification treatment and immersion drawing in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution.

  The polarizing plate of the present invention is characterized by being a polarizing plate bonded to at least one surface of a polarizer using the retardation film 2 of the present invention as a polarizing plate protective film.

  The cellulose ester film may be used on the other surface, or another polarizing plate protective film may be bonded. For example, commercially available cellulose ester films (for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC8UX-RHA, KC8UX-RHA, KC8UX KC4UXW-RHA-NC, manufactured by Konica Minolta Opto, Inc.) is also preferably used.

  When laminating the inclined retardation film 1 of the present invention and a polarizing plate, it is preferable to arrange the slow axis of the retardation film and the transmission axis of the polarizer so as to overlap each other within ± 3 °, and within ± 2 °. More preferably, it is arranged.

  In addition to the antiglare layer or the clear hard coat layer, the polarizing plate protective film used on the viewing side of the display device preferably has an antireflection layer, an antistatic layer, an antifouling layer, and a backcoat layer.

<Preparation of the inclined retardation film 103: Preparation of the raw film 101>
<Fine particle dispersion 1>
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose ester A was added to a pressurized dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The dope 1 was prepared by filtering using 244.

<Composition of dope 1>
Methylene chloride 210 parts by mass Ethanol 23 parts by mass Methyl methacrylate-styrene copolymer TX320XL
(MS resin made by Denki Kagaku Kogyo)
(Weight average molecular weight 100000, molar ratio 50:50) 100 parts by mass Particulate additive solution 1 1 part by mass The above was put into a sealed container and dissolved while stirring to prepare a dope solution. The adjusted dope was co-cast using an apparatus described in FIG. 1 of JP-A-2007-86254 on an endless stainless steel belt having an infinite traveling length of 2 m. The temperature of the stainless steel belt was 35 ° C.

  The solvent was evaporated on the stainless steel belt, and the web was peeled off from the stainless steel belt. The peeled web was cut to 1.5 m width with a slitter, the web was introduced into a tenter dryer, both ends were gripped with clips and dried at 135 ° C. while stretching 1.3 times in the width direction, Drying was completed while alternately passing a large number of rolls arranged vertically in a roll dryer having each drying zone at 125 ° C., and a raw film 101 having a dope 1 layer of 80 μm and a width of 1500 mm was produced. .

  The raw film 101 had Ro = 4 nm, Rth = 9 nm, and β = 0 °. Tg was 100 ° C.

<Manufacture of laminated raw film with different elastic modulus>
A polyimide adhesive tape (360A, manufactured by Nitto Denko) was bonded to the original film 101 at room temperature using a laminator. The tape had a thickness of 53 μm and a tensile elastic modulus of 1700 MPa.
<Inclined orientation treatment>
The laminated original film was allowed to pass through each zone as shown in FIG. 4 in a state in which a transport tension of 0.38 N / cm was applied in the MD direction by a pair of nip rolls of inclined orientation zones.

  At that time, a rubber roll having a diameter of 100 mm was installed so that the distance between the centers of the rolls was 250 mm, and the shrinkage in the TD direction (width regulation roll) was regulated.

  The atmospheric temperature of each zone was set so that the temperature would be the following set temperature, and the laminated original film was passed through. Processing time refers to the total time passing through the tilted alignment zone.

At this time, the film set temperatures in each zone were as follows.
T1 = 124 ° C., T2 = 170 ° C., T3 = 83 ° C., t1 = 0.19 seconds, t2 = 0.35 seconds Therefore, the temperature gradient at the time of temperature rise is 242 ° C./second (= (170-124) / 0 19), the temperature gradient at the time of temperature decrease was −247 ° C./second (= (83-170) /0.35).

  The temperature control of each zone was performed by the following method.

  Preheating zone: Hot air was blown onto the front and back of the film being transported to preheat. Two rolls and wind shields were installed between the preheating zone and the inclined orientation zone so that the temperature of each zone could be controlled independently.

  Inclined orientation zone: The film was passed between two heated rolls in contact. Thereafter, hot air was blown onto the front and back of the film being conveyed.

  Two rolls and wind shields were also installed between the inclined orientation zone and the cooling zone so that the temperature of each zone could be controlled independently.

  Cooling zone: Immediately after passing through the two rolls, cooling was performed by blowing cold air on the front and back of the film.

  The film width upon exiting the cooling zone contracted by 2% compared to the film width immediately before entering the preheating zone.

  Subsequently, the film subjected to the tilt alignment treatment was stretched by 10% (1.10 times) in the TD direction at 160 ° C. using a tenter to obtain the tilted retardation film 103 of the present invention.

  Only the MD tension was changed, and the other conditions were the same as the preparation of the inclined retardation film 103, and the inclined retardation films 101 and 102 were prepared.

  Further, in the production of the gradient retardation film 103, instead of methyl methacrylate-styrene copolymer, styrene-maleic anhydride copolymer (manufactured by Nova Chemical Co., Ltd., trade name: Dilark D332) (weight average molecular weight 80000, A gradient retardation film 104 was prepared using a molar ratio of 45:45:10). The optical evaluation is shown in Table 1.

<Preparation of retardation film 2>
A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose ester C was added to a pressurized dissolution tank containing a solvent while stirring. This was heated and stirred to dissolve completely, and then an additive and an ultraviolet absorber were added and dissolved. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

  In addition to adding 100 parts by mass of the main dope solution and 5 parts by mass of the fine particle additive solution, mix thoroughly with an in-line mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ), and then use a belt casting device to It was cast uniformly on a 2 m stainless steel band support.

  On the stainless steel band support, the solvent was evaporated until the residual solvent amount became 110%, and the stainless steel band support was peeled off. When peeling, the film is stretched so that the longitudinal (MD) stretch ratio is 1.1 times, and then both ends of the web are held by a tenter, and the stretch ratio in the width (TD) direction is 1.3. It extended | stretched so that it might become double.

After stretching, hold for several seconds while maintaining its width, release the width holding after relaxing the tension in the width direction, further carry for 30 minutes in the third drying zone set at 125 ° C., and perform drying, A retardation film 201 having a film thickness of 50 μm having a width of 1.5 m, a knurling having a width of 1 cm at the end and a height of 8 μm was produced.
<Composition of main dope solution>
Methylene chloride 390 parts by weight Ethanol 80 parts by weight Cellulose ester (acetyl group substitution degree 1.5 propionyl group substitution degree 0.9)
100 parts by mass Sugar ester compound Compound 3 6.0 parts by mass Polyester D 1 6.0 parts by mass Next, retardation films 202 to 204 shown in Table 2 were produced by changing the stretching conditions.

<Evaluation>
Ro ′, Rth ′, β1, L40, Ro, Rth, L were measured at 23 ° C. using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments) and a micro-area birefringence measurement device manufactured by Mizoji Optical Industry Co., Ltd. The measurement was performed under an atmosphere of 55% RH. The sample used was stored for 24 hours under the same conditions.
<Preparation of polarizing plate>
A polarizing plate was prepared using the retardation film 2 (201 to 204) as a polarizing plate protective film.

On the viewing side, a commercially available cellulose ester film (manufactured by Konica Minolta Tac KC-8UY, manufactured by Konica Minolta Opto Co., Ltd.) was used to produce a polarizing plate according to the following steps 1-5.
Step 1: It was immersed in a 2 mol% sodium hydroxide solution at 50 ° C. for 90 seconds, then washed with water and dried to saponify the side to be bonded to the polarizer.
Step 2: A polarizer was prepared by adsorbing iodine to a stretched polyvinyl alcohol film, and the polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.
Step 3: Excess adhesive adhered to the polarizer in Step 2 was gently wiped, and this was placed on the retardation film 2 treated in Step 1 and a commercially available cellulose ester film.
Process 4: The retardation film 2, the polarizer and the commercially available cellulose ester film laminated in the process 3 were bonded at a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.
Step 5: A sample in which the polarizer prepared in Step 4 was bonded to the retardation film 2 and a commercially available cellulose ester film was dried in a dryer at 80 ° C. for 5 minutes to prepare a polarizing plate.

  Similarly, polarizing plates 2 to 4 were produced. And the retardation phase film 1 (101-104) was bonded with the adhesive so that it might become the structure of Table 3 to the phase difference film 2 side of the polarizing plates 1-4, and the laminated phase difference film structure was produced. At this time, it is preferable that the in-plane slow axis of the laminated retardation film and the absorption axis of the polarizing plate are orthogonally bonded.

  A retardation film described in Example 1 of JP2009-98645A was used as a comparative polarizing plate protective film, and a comparative polarizing plate 1 was produced in the same manner as the polarizing plate 1.

Table 3 shows the laminated retardation film configuration and its optical evaluation.
<Production of liquid crystal display device>
Using the laminated retardation film configuration and the comparative polarizing plate, a liquid crystal panel was prepared as follows, and the characteristics as a liquid crystal display device were evaluated.

  The polarizing plates on both sides that had been bonded in advance to the 17-inch display SyncMaster 743BM manufactured by Samsunung Co., Ltd. were peeled off, and the prepared polarizing plates 1 to 4 were bonded to the glass surfaces of the liquid crystal cells, respectively.

  At that time, the polarizing plate is bonded so that the inclined retardation film 1 of the present invention is on the liquid crystal cell side and the absorption axis is directed in the same direction as the previously bonded polarizing plate. The liquid crystal display devices 1 to 4 and the comparative liquid crystal display device 1 were manufactured as shown in Table 3 so as to have the configuration of FIG.

<Evaluation of viewing angle: A. >
The measurement was performed after the backlight of each liquid crystal display device was lit continuously for one week in an environment of 23 ° C. and 55% RH. For the measurement, EZ-Contrast 160D manufactured by ELDIM was used to measure the luminance in the direction tilted up and down or left and right from the normal direction of the display screen of white display and black display on the liquid crystal display device, and the ratio (60 ° contrast) ) Is 10 as the viewing angle in the tilted direction, the vertical viewing angle is the sum of the upward and downward viewing angles, and the left and right viewing angles are the sum of the left and right viewing angles.

[Evaluation criteria for viewing angle]
Vertical viewing angle ◎: 110 ° or more ○: 90 ° or more and less than 110 ° △: 80 ° or more and less than 90 ×: Less than 80 ° left and right viewing angle ◎: 180 °
○: 130 ° or more and less than 180 ° Δ: 100 ° or more and less than 130 ° ×: less than 100 ° <Evaluation of color shift>
About each produced said liquid crystal display device, it measured about the color shift using the measuring machine (EZ-Contrast160D, ELDIM company make). In the CIE1931, xy chromaticity diagram, the neutral color (x, y) = (0.313, 0.34) when the neutral color is assumed to be a D65 light source, the tilt angle θ = 60 °, the azimuth angle The maximum color variation width Δxy in the vertical direction of the color at φ = 45 ° was compared.

[Evaluation criteria for color shift]
◎ Δxy is less than 0.05 ○ Δxy is from 0.05 to less than 0.07 Δ Δxy is from 0.07 to less than 0.09 × Δxy is 0.09 or more

  From Table 3, it was found that the polarizing plate of the present invention and the liquid crystal display device had excellent viewing angle and color shift characteristics.

a ′ slow axis of the tilted phase difference film b ′ fast axis of the tilted phase difference film c ′ thickness direction axis of the tilted phase difference film β1 average tilt angle θ1, θ2 axis c ′ and the major axis or short axis of the refractive index ellipsoid Angle formed with axis 1 First protective film 2 First polarizer 3 First retardation film 4 First polarizing plate 4
DESCRIPTION OF SYMBOLS 5 Twist nematic type liquid crystal cell 6 2nd phase difference film 7 2nd polarizer 8 2nd protective film 9 2nd polarizing plate 10 Backlight unit A Preheating zone B Inclination orientation zone C Cooling zone 100 MD tension addition roll (R1, R2, R3, R4 nip roll)
DESCRIPTION OF SYMBOLS 101 Width control roll 102 Non-contact thermometer 103,104 TD stretching apparatus 105 Film unwinding apparatus 106 Film winding apparatus 107 Partition plate 108 Partition roll a Width direction axis (TD direction) of inclined retardation film
b Longitudinal axis of tilted retardation film (MD direction)
c Thickness direction axis of tilted retardation film x Direction axis with maximum refractive index in the film plane (in-plane slow axis)
y Direction axis that minimizes the refractive index in the film plane z Film thickness direction axis β Average tilt angle θ Angle formed by the in-plane slow axis of the film and the longitudinal direction x ′ perpendicular to z ′ of the refractive index ellipsoid Direction axis where the refractive index is the largest among the planes to be produced y ′ direction axis where the refractive index is the smallest among the planes orthogonal to z ′ of the refractive index ellipsoid z ′ the thickness direction axis of the refractive index ellipsoid nx ′ x ′ direction Refractive index of ny 'y' direction refractive index nz 'z' direction refractive index

Claims (4)

The chromatic dispersion L40 observed from the direction inclined by 40 ° from the normal direction of the film surface is 0.9 to 1.09, the average inclination angle β1 is 50 ° to 85 °, and the refractive index ellipsoid in-plane retardation Ro. An inclined retardation film, wherein “is 0 ≦ Ro ′ ≦ 80 nm and refractive index ellipsoid thickness retardation Rth ′ is −200 ≦ Rth ′ ≦ −30 nm.
Here, when the short direction of the inclined retardation film is a ′, the long direction is b ′, and the thickness direction axis is c ′, the average inclination angle β1 is the long direction b ′ of the inclined retardation film and the thickness direction. It is an average value in the thickness direction of the angle formed by the major axis of the ellipsoid and the longitudinal direction b ′ in the cross section of the refractive index ellipsoid of the inclined retardation film on the b′c ′ plane of the axis c ′. .
The wavelength dispersion L40 is a ratio of retardation values observed from a direction inclined by 40 ° in any direction from the normal direction of the film surface, and is R40 ′ (480) / R40 ′ (630). The values in parentheses represent the measurement light wavelength (nm).
Ro ′ = (nx′−ny ′) × d1
Rth ′ = {(nx ′ + ny ′) / 2−nz ′} × d1
Further, in the cross section of the refractive index ellipsoid of the tilted phase difference film in the b′c ′ plane of the tilted phase difference film, of the major axis and the minor axis of the ellipsoidal section, the thickness direction axis c ′ of the film The axis with the smaller angle is the z ′ axis, the refractive index in that direction is nz ′, the plane having the maximum refractive index among the planes orthogonal to the z ′ axis is the x ′ axis, and the refractive index in that direction is nx. Of the plane orthogonal to the z ′ direction of the refractive index ellipsoid, the direction in which the refractive index is minimum is the y ′ axis, the refractive index in that direction is ny ′, and the thickness of the tilted retardation film is d1 (nm) To express. The measurement wavelength is 590 nm.   The inclined retardation film according to claim 1, wherein the inclined retardation film is an inclined retardation film 1 and contains a compound having negative intrinsic birefringence. The chromatic dispersion L40 observed from the direction inclined by 40 ° from the normal direction of the film surface is 0.9 to 1.09, the average inclination angle β1 is 50 ° to 85 °, and the refractive index ellipsoid in-plane retardation Ro. Inclined retardation film 1 in which “is 0 ≦ Ro ′ ≦ 80 nm and refractive index ellipsoidal thickness retardation Rth ′ is −200 ≦ Rth ′ ≦ −30 nm, 10 ≦ Ro ≦ 100 nm, 20 ≦ Rth ≦ 230 nm and the surface A liquid crystal display device having a laminated retardation film configuration with a retardation film 2 having a wavelength dispersion L of an inner retardation of 0.9 or more and less than 1.0.
Ro ′ = (nx′−ny ′) × d1
Rth ′ = {(nx ′ + ny ′) / 2−nz ′} × d1
Here, when the short direction of the inclined retardation film 1 is a ′, the long direction is b ′, and the thickness direction axis is c ′, the average inclination angle β1 is the long direction b ′ of the inclined retardation film 1. The average in the thickness direction of the angle formed by the major axis of the ellipsoid and the longitudinal direction b ′ in the cross section of the refractive index ellipsoid of the inclined retardation film 1 on the b′c ′ plane of the thickness direction axis c ′. Value.
The wavelength dispersion L40 is a ratio of retardation values observed from a direction inclined by 40 ° in any direction from the normal direction of the film surface, and is R40 ′ (480) / R40 ′ (630). The values in parentheses represent the measurement light wavelength (nm).
The wavelength dispersion L40 is a ratio of retardation values observed from a direction inclined by 40 ° in any direction from the normal direction of the film surface, and is R40 ′ (480) / R40 ′ (630). The values in parentheses represent the measurement light wavelength (nm).
Ro = (nx−ny) × d2
Rth = {(nx + ny) / 2−nz} × d2
Here, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the retardation film 2, and ny is in the direction y orthogonal to the direction x in the in-plane direction of the retardation film 2. The refractive index is represented, nz represents the refractive index in the thickness direction z of the retardation film 2, and d2 (nm) represents the thickness of the retardation film 2.
The chromatic dispersion L is Ro (480) / Ro (630). The values in parentheses represent the measurement light wavelength (nm). Ro ″, Rth ″ of the refractive index ellipsoid of the laminated retardation film configuration is 20 ≦ Ro ″ ≦ 100 nm, 70 ≦ Rth ″ ≦ 200 nm, and the average inclination angle βo is 10 ≦ βo ≦ 45 °. The liquid crystal display device according to claim 3.
Here, when the in-plane slow axis of the laminated retardation film is a, the in-plane fast axis is b, and the thickness direction axis is c, the average inclination angle βo is the in-plane fast axis of the laminated retardation film. This is the average value in the thickness direction of the angle formed by the major axis of the ellipsoid and the in-plane fast axis b in the cross section of the refractive index ellipsoid of the laminated retardation film on the bc plane of the thickness direction axis c. .
In the cross section of the refractive index ellipsoid of the laminated phase difference film in the bc plane of the laminated phase difference film, Ro ″ and Rth ″ of the refractive index ellipsoid are the laminating positions of the major axis and the short axis of the ellipsoidal cross section. The axis having the smaller angle with respect to the thickness direction axis c of the retardation film is defined as the z ″ axis, the refractive index in that direction is nz ″, and the direction in which the refractive index is maximum among the planes orthogonal to the z ″ axis direction is x “Axis, the refractive index in that direction is nx”, and the z ”axis direction of the refractive index ellipsoid is the direction in which the refractive index is the smallest in the y” axis, and the refractive index in that direction is ny ”, It is expressed as follows. The measurement wavelength is 590 nm.
Ro ″ = (nx ″ −ny ″) × (d1 + d2)
Rth ″ = {(nx ″ + ny ″) / 2−nz ″} × (d1 + d2)

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