JP2007114762A - Polarizing plate having optical compensation layer, liquid crystal panel using the polarizing plate having optical compensation layer, liquid crystal display device and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate having optical compensation layer, capable of contributing the thinning, improving visual angle characteristics, realizing high contrast, preventing interference irregularities and thermal irregularities, suppressing color shifts, exhibiting proper color reproducibility and effectively preventing light leak in the black display, and to provide a liquid crystal panel, a liquid crystal display device and an image display device that uses such a polarizing plate, having an optical compensation layer. <P>SOLUTION: The polarizing plate having optical compensation layer has a polarizer, a first optical compensation layer and a second optical compensation layer, in this order. The first optical compensation layer has a refractivity distribution of nx>ny=nz, and exhibits wavelength distribution characteristics such that the in-plane phase difference Re<SB>1</SB>becomes smaller, the shorter the wavelength becomes, wherein the in-plane phase difference Re<SB>1</SB>is 90 to 160 nm. The second optical compensation layer is a film layer, having a refractivity distribution of nx=ny>nz, an in-plane phase difference Re<SB>2</SB>of 0 to 20 nm and a phase difference in the thickness direction Rth<SB>2</SB>of 30 to 300 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polarizing plate with an optical compensation layer, a liquid crystal panel using the polarizing plate with an optical compensation layer, a liquid crystal display device, and an image display device. More specifically, the present invention contributes to thinning, prevents thermal unevenness, and can satisfactorily prevent light leakage in black display, and such a polarizing plate with an optical compensation layer. The present invention relates to a liquid crystal panel, a liquid crystal display device, and an image display device using the above.

  As a VA mode liquid crystal display device, a transflective liquid crystal display device has been proposed in addition to a transmissive liquid crystal display device and a reflective liquid crystal display device (see, for example, Patent Documents 1 and 2). The transflective liquid crystal display device uses external light in a bright place in the same manner as the reflective liquid crystal display device, and allows display to be visually recognized by an internal light source such as a backlight in a dark place. In other words, the transflective liquid crystal display device employs a display method having both a reflective type and a transmissive type, and switches to either the reflective mode or the transmissive mode depending on the surrounding brightness. As a result, the transflective reflective liquid crystal display device can be clearly displayed even in a dark place while reducing power consumption, and is therefore preferably used for, for example, a display unit of a portable device.

  As a specific example of such a transflective reflective liquid crystal display device, for example, a reflective film in which a window for light transmission is formed on a metal film such as aluminum is provided on the inner side of the lower substrate, and this reflective film is semitransparent A liquid crystal display device that functions as a reflecting plate can be given. In such a liquid crystal display device, in the reflection mode, external light incident from the upper substrate side passes through the liquid crystal layer, is reflected by the reflective film inside the lower substrate, and passes through the liquid crystal layer again. The light is emitted from the upper substrate side and contributes to display. On the other hand, in the transmissive mode, light from the backlight incident from the lower substrate side passes through the liquid crystal layer through the window portion of the reflective film, and then is emitted from the upper substrate side to contribute to display. Therefore, in the reflective film formation region, the region where the window is formed becomes the transmissive display region, and the other region becomes the reflective display region. However, in the conventional reflective or transflective VA mode liquid crystal display device, there is a problem in that light leakage occurs in black display and the contrast is lowered, which has not been solved for a long time.

As an attempt to solve such a problem, a laminated retardation layer obtained by laminating a retardation film having a wavelength dispersion characteristic that a retardation value becomes smaller as the wavelength is shorter, and a retardation layer made of a liquid crystal coating layer Has been proposed (see, for example, Patent Document 3). However, in such a laminated retardation layer, since the liquid crystal monomer is directly coated on the retardation film by dissolving it in an organic solvent, the organic solvent erodes the retardation film, resulting in damage to the retardation film and retardation. There arises a problem that the film becomes cloudy. In addition, when the retardation layer composed of a liquid crystal layer is formed by coating, the retardation in the thickness direction is controlled by the coating film thickness after drying, so the coating film thickness must be accurately controlled. In addition, there are many troublesome work in quality control in the work process, such as the need to pay attention to bubbles and foreign matters mixed in the coating film, and there is a problem that the production yield is lowered.
Japanese Patent Laid-Open No. 11-242226 Japanese Patent Laid-Open No. 2001-209065 JP 2004-326089 A

  The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to contribute to the reduction in thickness and to improve the viewing angle characteristics while realizing high contrast, and to achieve interference unevenness and heat unevenness. Used, a polarizing plate with an optical compensation layer capable of preventing color leakage, suppressing good color reproducibility, and preventing light leakage in black display, and such a polarizing plate with an optical compensation layer A liquid crystal panel, a liquid crystal display device, and an image display device are provided.

The polarizing plate with an optical compensation layer of the present invention has a polarizer, a first optical compensation layer, and a second optical compensation layer in this order, and the first optical compensation layer has nx> ny = nz. The in-plane retardation Re ₁ is smaller as the wavelength is shorter, the in-plane retardation Re ₁ is 90 to 160 nm, and the second optical compensation layer Is a film layer, has a refractive index distribution of nx = ny> nz, an in-plane retardation Re ₂ of 0 to ₂₀ nm, and a thickness direction retardation Rth ₂ of 30 to 300 nm. .

  In a preferred embodiment, the first optical compensation layer is a stretched film layer and includes a polycarbonate having a fluorene skeleton.

  In a preferred embodiment, the first optical compensation layer is a stretched film layer and contains cellulose acetate.

  In a preferred embodiment, the first optical compensation layer is a stretched film layer and includes two or more aromatic polyester polymers having different wavelength dispersion characteristics.

  In a preferred embodiment, the first optical compensation layer is a stretched film layer and includes a copolymer having two or more types of monomer units derived from monomers that form polymers having different wavelength dispersion characteristics.

  In a preferred embodiment, the first optical compensation layer is a composite film layer in which two or more kinds of stretched film layers having different wavelength dispersion characteristics are laminated.

  In a preferred embodiment, the second optical compensation layer contains a cyclic olefin resin and / or a cellulose resin.

In a preferred embodiment, the second optical compensation layer has a cholesteric alignment solidified layer having a selective reflection wavelength region of 350 nm or less, a refractive index distribution of nx = ny> nz, and an absolute value of a photoelastic coefficient. ^Has a layer made of a film containing a resin of 2 × 10 ⁻¹¹ m ² / N or less.

  According to another aspect of the present invention, a liquid crystal panel is provided. The liquid crystal panel includes the polarizing plate with an optical compensation layer and a liquid crystal cell.

  In a preferred embodiment, the liquid crystal cell is a reflective or transflective VA mode.

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

  According to still another aspect of the present invention, an image display device is provided. The image display device includes the polarizing plate with an optical compensation layer.

  As described above, according to the present invention, it contributes to thinning, improves viewing angle characteristics, realizes high contrast, prevents interference unevenness and thermal unevenness, suppresses color shift, and achieves good color reproduction. The present invention provides a polarizing plate with an optical compensation layer that can prevent the light leakage in black display, and a liquid crystal panel, a liquid crystal display device, and an image display device using such a polarizing plate with an optical compensation layer. Can do.

Such an effect is obtained by having a polarizer, a first optical compensation layer, and a second optical compensation layer in this order as a polarizing plate with an optical compensation layer, and the first optical compensation layer has nx > Ny = nz, having a chromatic dispersion characteristic in which the phase difference value, which is the optical path difference between extraordinary light and ordinary light, becomes smaller toward the shorter wavelength side, and the in-plane retardation Re ₁ is set to a predetermined value. The second optical compensation layer is a film layer, has a refractive index distribution of nx = ny> nz, and has an in-plane retardation Re ₂ and a thickness direction retardation Rth ₂ of a predetermined value. It can be expressed by being within the range.

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows:
(1) “nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction perpendicular to the slow axis in the plane (ie, fast phase) (Nz direction), and “nz” is the refractive index in the thickness direction. For example, “nx = ny” includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. In this specification, “substantially equal” is intended to include the case where nx and ny are different within a range that does not practically affect the overall polarization characteristics of the polarizing plate with an optical compensation layer.

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

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

  (4) The subscript “1” attached to the terms and symbols described in this specification represents the first optical compensation layer, and the subscript “2” represents the second optical compensation layer.

  (5) “λ / 2 plate” refers to converting linearly polarized light having a specific vibration direction into linearly polarized light having a vibration direction orthogonal to the vibration direction of the linearly polarized light, or converting right circularly polarized light to the left circle It has a function of converting into polarized light (or converting left circularly polarized light into right circularly polarized light). The λ / 2 plate has an in-plane retardation value of about ½ for a predetermined wavelength of light (usually in the visible light region).

  (6) “λ / 4 plate” means a plate having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The λ / 4 plate has an in-plane retardation value of about ¼ for a predetermined wavelength of light (usually in the visible light region).

A. Polarizing plate with optical compensation layer A-1. 1 is a schematic sectional view of a polarizing plate with an optical compensation layer according to a preferred embodiment of the present invention. As shown in FIG. 1, the polarizing plate with an optical compensation layer 10 includes a polarizer 11, a first optical compensation layer 12, and a second optical compensation layer 13 in this order.

  Each layer of the polarizing plate with an optical compensation layer is laminated via any appropriate pressure-sensitive adhesive layer or adhesive layer (not shown). Practically, any appropriate protective layer (not shown) is laminated on the side of the polarizer 11 where the optical compensation layer is not formed. Furthermore, a protective layer is provided between the polarizer 11 and the first optical compensation layer 12 as necessary.

  The total thickness of the polarizing plate with an optical compensation layer of the present invention is preferably 150 to 400 μm, more preferably 200 to 350 μm, and further preferably 230 to 330 μm. Therefore, the present invention can greatly contribute to thinning of an image display device (for example, a liquid crystal display device).

A-2. First optical compensation layer The first optical compensation layer has a refractive index of nx> ny = nz for use as a circular polarization mode in a transflective liquid crystal display device, particularly in a VA mode (vertical alignment mode). Positive A plate with distribution.

  The first optical compensation layer has a refractive index distribution of nx> ny = nz, and the luminance of the liquid crystal display device is improved by having the above refractive index distribution.

The first optical compensation layer exhibits a wavelength dispersion characteristic that the in-plane retardation Re ₁ becomes smaller as the wavelength becomes shorter. For example, in the first optical compensation layer, Re [650] / Re [550] is preferably 1.01 to 1.30, more preferably 1.02 to 1.22. Further, for example, in the first optical compensation layer, Re [450] / Re [550] is preferably 0.80 to 0.99, and more preferably 0.82 to 0.93.

  The first optical compensation layer is, for example, a stretched film layer and includes a polycarbonate having a fluorene skeleton (for example, described in JP-A-2002-48919), a stretched film layer, and cellulose acetate. (For example, described in JP-A No. 2000-137116), a stretched film layer, and two or more types of aromatic polyester polymers having different wavelength dispersion characteristics (for example, JP-A No. 2002-14234) Described in the publication), a stretched film layer and containing a copolymer having two or more types of monomer units derived from monomers that form polymers having different wavelength dispersion characteristics (described in WO00 / 26705), different Composite film layer in which two or more kinds of stretched film layers having wavelength dispersion characteristics are laminated Described in 2-120804 JP) are preferably used.

  The material for forming the first optical compensation layer may be, for example, a homopolymer (copolymer), a copolymer (copolymer), or a blend of a plurality of polymers. In the case of a blend, since it is necessary to be optically transparent, it is preferable that the compatible blend and the refractive indexes of the respective polymers are substantially equal. As a material for forming the first optical compensation layer, for example, a polymer described in JP-A No. 2004-309617 can be preferably used.

  Specific combinations of the blends include, for example, poly (methyl methacrylate) as a polymer having negative optical anisotropy, and poly (vinylidene fluoride), poly as a polymer having positive optical anisotropy. (Ethylene oxide), a combination with vinylidene fluoride / trifluoroethylene copolymer, etc .; as a polymer having negative optical anisotropy, polystyrene, styrene / lauroyl maleimide copolymer, styrene / cyclohexyl maleimide copolymer, styrene / Phenylmaleimide copolymer and the like, and a combination of poly (phenylene oxide) as a polymer having a positive optical anisotropy; and a styrene / maleic anhydride copolymer as a polymer having a negative optical anisotropy As a polymer having positive optical anisotropy, As a polymer having positive optical anisotropy, and an acrylonitrile / styrene copolymer, as a polymer having negative optical anisotropy, a combination of acrylonitrile / butadiene copolymer; a combination of a carbonate and the like. Among these, from the viewpoint of transparency, a combination of polystyrene as a polymer having negative optical anisotropy and poly (phenylene oxide) as a polymer having positive optical anisotropy is preferable. Examples of poly (phenylene oxide) include poly (2,6-dimethyl-1,4-phenylene oxide).

  Examples of the copolymer (copolymer) include a butadiene / styrene copolymer, an ethylene / styrene copolymer, an acrylonitrile / butadiene copolymer, an acrylonitrile / butadiene / styrene copolymer, a polycarbonate-based copolymer, and a polyester-based copolymer. Examples include copolymers, polyester carbonate copolymers, polyarylate copolymers, and the like. In particular, since a segment having a fluorene skeleton can have negative optical anisotropy, a polycarbonate having a fluorene skeleton, a polycarbonate copolymer having a fluorene skeleton, a polyester having a fluorene skeleton, a polyester copolymer having a fluorene skeleton, A polyester carbonate having a fluorene skeleton, a polyester carbonate copolymer having a fluorene skeleton, a polyarylate having a fluorene skeleton, a polyarylate copolymer having a fluorene skeleton, and the like are preferable.

The first optical compensation layer can function as a λ / 4 plate. The in-plane retardation Re ₁ of the first optical compensation layer is 90 to 160 nm, preferably 100 to 150 nm, and more preferably 110 to 140 nm.

The thickness of the first optical compensation layer can be set so that it can function appropriately as a λ / 4 plate. The thickness can be set such that a desired in-plane retardation Re ₁ is obtained. Specifically, the thickness of the first optical compensation layer is preferably 40 to 90 μm, more preferably 45 to 85 μm, and still more preferably 50 to 80 μm.

The in-plane retardation Re ₁ of the first optical compensation layer can be controlled by changing the stretching ratio and stretching temperature of the resin film exhibiting the above-described wavelength dispersion characteristics (reverse wavelength dispersion characteristics).

  The stretching method can be selected according to the type of resin used. For example, a longitudinal uniaxial stretching method, a lateral uniaxial stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, or the like can be used.

The draw ratio is the in-plane retardation Re ₁ desired for the first optical compensation layer, the desired thickness for the first optical compensation layer, the type of resin used, the thickness of the film used, the stretching temperature, etc. Depending on the case, it can be changed appropriately. Specifically, the draw ratio is preferably 1.6 to 2.24 times, more preferably 1.6 to 2.22 times, and still more preferably 1.7 to 2.20 times. By performing stretching at such a stretching ratio, the first optical compensation layer having an in-plane retardation Re ₁ that can sufficiently exhibit the effects of the present invention and having a refractive index distribution of nx> ny = nz is obtained. Can be obtained.

The stretching temperature is the in-plane retardation Re ₁ desired for the first optical compensation layer, the desired thickness for the first optical compensation layer, the type of resin used, the thickness of the film used, the draw ratio, etc. Depending on the case, it can be changed appropriately. Specifically, the stretching temperature is preferably 150 to 250 ° C, more preferably 170 to 240 ° C, and still more preferably 190 to 240 ° C. By performing stretching at such a stretching temperature, the first optical compensation layer having an in-plane retardation Re ₁ that can sufficiently exhibit the effects of the present invention and having a refractive index distribution of nx> ny = nz is obtained. Can be obtained.

  The method for forming the first optical compensation layer is not particularly limited, and any appropriate method can be adopted. For example, a solution in which the above-described forming material is dissolved in a solvent is prepared, and this is applied in the form of a film on a base film having a smooth surface or a metal endless belt, and then the solvent is removed by evaporation. And a method of forming the optical compensation layer.

  The solvent that can be used for the coating is not particularly limited, and any appropriate method can be adopted. For example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene and orthodichlorobenzene; phenols such as phenol and parachlorophenol; benzene, toluene, xylene, methoxybenzene, Aromatic hydrocarbons such as 1,2-dimethoxybenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N-methyl-2-pyrrolidone; ethyl acetate, butyl acetate Ester solvents such as t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol Alcohol solvents such as methyl ether, propylene glycol, dipropylene glycol and 2-methyl-2,4-pentanediol; Amide solvents such as dimethylformamide and dimethylacetamide; Nitrile solvents such as acetonitrile and butyronitrile; Diethyl ether and Di And ether solvents such as butyl ether and tetrahydrofuran; carbon disulfide; and cellosolves such as ethyl cellosolve and butyl cellosolve. These solvents may be used alone or in combination of two or more.

  The coating method is not particularly limited, and any appropriate method can be adopted. For example, a spin coating method, a roll coating method, a flow coating method, a printing method, a dip coating method, a casting film forming method, a bar coating method, a gravure printing method and the like can be mentioned. Moreover, in the case of coating, the superposition | polymerization method of a polymer layer is also employable as needed.

  The material for forming the base film is not particularly limited, and any appropriate material can be adopted. For example, a polymer excellent in transparency is preferably mentioned, and a thermoplastic resin is preferred because it is suitable for stretching treatment and shrinkage treatment.

  The thickness of the base film is preferably 10 to 1000 μm, more preferably 20 to 500 μm, and still more preferably 30 to 100 μm.

A-3. Second Optical Compensation Layer The second optical compensation layer is a film layer, has a refractive index profile of nx = ny> nz, and can function as a so-called negative C plate. Since the second optical compensation layer has such a refractive index distribution, the birefringence of the liquid crystal layer of the VA mode liquid crystal cell can be particularly favorably compensated. That is, the second optical compensation layer causes deterioration in viewing angle characteristics due to the loss of isotropic property due to the influence of liquid crystal molecules when viewed from an oblique direction in a VA mode (vertical alignment mode) liquid crystal display device. It is for removing. As a result, a liquid crystal display device with significantly improved viewing angle characteristics can be obtained.

In the present specification, “nx = ny” includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. Therefore, the second optical compensation layer has an in-plane retardation Re _2. And may have a slow axis. The in-plane retardation Re _{2 that} is practically acceptable for the negative C plate is 0 to 20 nm, preferably 0 to 10 nm, and more preferably 0 to 5 nm.

The thickness direction retardation Rth2 of the _second optical compensation layer is 30 nm or more, preferably 40 nm or more, more preferably 60 nm or more, still more preferably 80 nm or more, and even more preferably 100 nm or more. Further, the phase difference Rth ₂ is 300 nm or less, preferably 180 nm or less, more preferably 150 nm or less, and further preferably 120 nm or less. The thickness of the second optical compensation layer from which such a thickness direction retardation Rth ₂ can be obtained can be changed depending on the material used, the use, and the like.

  The thickness of the second optical compensation layer is preferably 20 to 80 μm, more preferably 35 to 75 μm, and still more preferably 40 to 70 μm.

  The second optical compensation layer can be obtained, for example, by biaxially stretching a plastic film.

The second optical compensation layer is a film layer, and is particularly preferably a film layer containing a resin having an absolute value of a photoelastic coefficient of 2 × 10 ⁻¹¹ m ² / N or less. In the present invention, since the second optical compensation layer is a film layer, an adjacent layer (first optical compensation layer) is formed by performing heat drying or the like for fixing the liquid crystal alignment as in the case of forming a coating layer. ) Can be avoided. In addition, when the second optical compensation layer is formed by coating, the thickness direction retardation is controlled by the coating film thickness after drying, so the coating film thickness must be accurately controlled, There are many troublesome work in quality control in the work process, such as it is necessary to pay attention to bubbles and foreign matters mixed in the coating film, and there is a problem that the production yield decreases, but such a problem is avoided if it is a film layer it can. Examples of the resin that can form such a film layer (plastic film layer) include a cyclic olefin resin and a cellulose resin. These may be used alone or in combination of two or more. Among these, a cyclic olefin resin is particularly preferable.

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

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

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

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

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

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

  Any appropriate cellulosic resin can be adopted as the cellulosic resin. A typical example is an ester of cellulose and an acid. Preferred is an ester of cellulose and a fatty acid.

Specific examples of the cellulose resin include cellulose triacetate (triacetyl cellulose: TAC), cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Among these, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferable. This is because it has low birefringence and high transmittance. Many products are commercially available, and TAC is advantageous in terms of availability and cost. TAC is a film that becomes a so-called negative C plate in which the refractive index ellipsoid has a relationship of nx = ny> nz without stretching. For example, by biaxially stretching TAC, the thickness direction retardation (Rth ₂ ) can be controlled, and a desired negative C plate can be obtained.

  Specific examples of TAC commercial products are trade names “UV-50”, “UV-80”, “SH-50”, “SH-80”, “TD-80U”, “TD” manufactured by Fuji Photo Film Co., Ltd. -TAC "," UZ-TAC "; trade name" KC series "manufactured by Konica; trade name" cellulose triacetate 80 [mu] m series "manufactured by Lonza Japan; Among these, “TD-80U” is preferable. This is because the transmittance and durability are excellent. “TD-80U” has excellent compatibility particularly in a TFT type liquid crystal display device.

  A 2nd optical compensation layer is obtained by extending | stretching the film formed from the said cyclic olefin resin or the said cellulose resin. As a method for forming a film from a cyclic olefin-based resin or a cellulose-based resin, any appropriate forming method can be adopted. Specific examples include compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method, casting method (casting) method and the like. An extrusion method or a casting method is preferred. This is because the smoothness of the resulting film can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, the characteristics desired for the second optical compensation layer, and the like. In addition, since many film products are marketed, the said cyclic olefin resin and the said cellulose resin may use the said commercial film as it is for a extending | stretching process.

  The method for stretching the film may be selected according to the type of resin used. For example, a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, or the like can be used, and a sequential biaxial stretching method or the like can be preferably used.

  The stretching ratio of the film can vary depending on the in-plane retardation value and thickness desired for the second optical compensation layer, the type of resin used, the thickness of the film used, the stretching temperature, and the like. Specifically, the draw ratio is preferably 1.17 to 1.47 times, more preferably 1.22 to 1.42 times, and most preferably 1.27 to 1.37 times. By stretching at such a magnification, a second optical compensation layer having an in-plane retardation capable of appropriately exhibiting the effects of the present invention can be obtained.

  The stretching temperature of the film can vary depending on the in-plane retardation value and thickness desired for the second optical compensation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, for example, when a film made of a cyclic olefin resin is used, the stretching temperature is preferably 165 to 185 ° C, more preferably 170 to 180 ° C, and most preferably 173 to 178 ° C. By stretching at such a temperature, a second optical compensation layer having an in-plane retardation capable of appropriately exhibiting the effects of the present invention can be obtained.

The second optical compensation layer has a relationship of nx = ny> nz with the liquid crystal layer, specifically, the cholesteric alignment solidified layer, and the absolute value of the photoelastic coefficient is 2 × 10 ⁻¹¹ m ² / N. A laminated body with a layer made of a film containing the following resin (also referred to as a resin film layer in the present invention) may be used.

Examples of the material for forming the resin film layer include a cyclic olefin resin and a cellulose resin. The cyclic olefin resin and the cellulose resin are as described in the above section A-3. The method for forming the resin film layer is also as described in the above section A-3. The absolute value of the photoelastic coefficient of these resins is preferably 2 × 10 ⁻¹¹ m ² / N or less.

  In the second optical compensation layer, the cholesteric alignment fixed layer is formed from a liquid crystal composition. Any appropriate liquid crystal material can be used as the liquid crystal material contained in the liquid crystal composition. For example, a liquid crystal material (nematic liquid crystal) whose liquid crystal phase is a nematic phase is preferable. Moreover, a liquid crystal polymer and a liquid crystal monomer can also be used.

  The liquid crystal material may exhibit a liquid crystallinity mechanism either lyotropic or thermotropic. The alignment state of the liquid crystal is preferably homogeneous alignment.

  The content of the liquid crystal material in the liquid crystal composition is preferably 75 to 95% by weight, more preferably 80 to 90% by weight. When the content of the liquid crystal material is less than 75% by weight, the composition cannot sufficiently exhibit a liquid crystal state, and a desired cholesteric alignment may not be obtained. On the other hand, when the content of the liquid crystal material exceeds 95% by weight, the proportion of the chiral agent to be described later in the liquid crystal composition decreases, so that it becomes insufficient to impart twist to the alignment of the liquid crystal, and the desired cholesteric is also achieved. Obtaining orientation may be difficult.

  The liquid crystal material is preferably a liquid crystal monomer (for example, a polymerizable monomer or a crosslinkable monomer). This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking the liquid crystal monomer. After aligning the liquid crystal monomer, the alignment state of the liquid crystal monomer can be fixed, for example, by polymerizing or cross-linking the liquid crystal monomers. Here, a polymer is formed by polymerization, or a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, the cholesteric alignment solidified layer in the formed second optical compensation layer does not undergo a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change unique to the liquid crystal compound, for example. As a result, the cholesteric alignment solidified layer in the second optical compensation layer becomes an extremely stable optical compensation layer that is not affected by temperature change.

  For example, any appropriate liquid crystal monomer is used as the liquid crystal monomer. For example, JP-T 2002-533742 (WO00 / 37585), European Patent No. 358208 (US Patent No. 5211877), European Patent No. 66137 (US Patent No. 4388453), WO93 / 22397, European Patent No. 0261712, Germany Polymerizable mesogenic compounds described in Japanese Patent No. 19504224, German Patent No. 4408171, British Patent 2280445, and the like can be used. Specific examples of the polymerizable mesogen compound described in these publications include trade name LC242 from BASF, trade name E7 from Merck, trade name LC-Silicon 3767 from Wacker-Chem.

  The liquid crystal composition forming the cholesteric alignment fixed layer also contains a chiral agent. The content of the chiral agent in the liquid crystal composition is, for example, 5 to 23% by weight, and preferably 10 to 20% by weight. For example, when the content of the chiral agent is less than 5% by weight, it becomes difficult to sufficiently impart twist to the alignment of the liquid crystal, and there is a possibility that cholesteric alignment cannot be obtained. This makes it difficult to control the wavelength range of selective reflection of the cholesteric alignment solidified layer to a desired band (on the low wavelength side). On the other hand, when the content of the chiral agent is more than 23% by weight, the temperature range in which the liquid crystal material exhibits a liquid crystal state becomes narrow, and it is necessary to precisely control the temperature when forming the cholesteric alignment solidified layer. This makes it difficult to produce a cholesteric alignment solidified layer, which may lead to a decrease in yield.

  You may use a chiral agent in combination of 1 type or 2 types or more. In addition, it is preferable to use a polymerizable chiral agent as the chiral agent. Further, for example, chiral compounds described in RE-A 4342280, German Patent Application No. 19520660.6, German Patent Application No. 192074.1 can be used.

As the chiral agent, for example, any appropriate agent that can impart a desired cholesteric alignment to the liquid crystal material is used. The torsional force of the chiral agent that can be used is, for example, 1 × 10 ⁻⁶ nm ⁻¹ · (wt%) ⁻¹ or more, preferably 1 × 10 ⁻⁵ nm ⁻¹ · (wt%) ⁻¹ to 1 ×. 10 ⁻² nm ⁻¹ · (wt%) ⁻¹ , more preferably 1 × 10 ⁻⁴ nm ⁻¹ · (wt%) ⁻¹ to 1 × 10 ⁻³ nm ⁻¹ · (wt%) ^−1. It is. By using a chiral agent having a twisting force in the above range, the helical pitch of the cholesteric alignment solidified layer can be controlled in a desired range. For example, when a chiral agent having the same torsional force is used, the wavelength range of selective reflection of the formed optical compensation layer becomes lower as the content of the chiral agent in the liquid crystal composition is larger. For example, when the content of the chiral agent in the liquid crystal composition is the same, the greater the torsional force of the chiral agent, the lower the wavelength range of selective reflection of the formed optical compensation layer.

Specifically, for example, when the wavelength range of selective reflection of the cholesteric alignment solidified layer to be formed is in the range of 200 to 220 nm, a chiral agent having a twisting force of 5 × 10 ⁻⁴ nm ⁻¹ · (wt%) ⁻¹ is used. What is necessary is just to make it contain in the ratio of 11-13 weight% in a liquid-crystal composition. For example, when the wavelength range of selective reflection of the cholesteric alignment solidified layer to be formed is set to a range of 290 to 310 nm, a chiral agent having a twisting force of 5 × 10 ⁻⁴ nm ⁻¹ · (wt%) ⁻¹ is included in the liquid crystal composition. What is necessary is just to make it contain in the ratio of 7-9 weight%.

  The wavelength range of selective reflection of the cholesteric alignment fixed layer to be formed is preferably 380 nm or less, more preferably 350 nm or less, and further preferably 320 nm or less.

  Preferably, the liquid crystal composition forming the cholesteric alignment fixed layer further contains at least one of a polymerization initiator and a crosslinking agent (curing agent). By using a polymerization initiator or a crosslinking agent (curing agent), a cholesteric structure (cholesteric alignment) formed by the liquid crystal material in a liquid crystal state can be fixed. As such a polymerization initiator or crosslinking agent, any appropriate substance can be used as long as the effects of the present invention can be obtained.

  Examples of the polymerization initiator include benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN). Examples of the crosslinking agent (curing agent) include an ultraviolet curing agent, a photocuring agent, and a thermosetting agent. Specifically, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, a metal chelate crosslinking agent, etc. are mentioned, for example. The polymerization initiator or the crosslinking agent (curing agent) may be used alone or in combination of two or more.

  The content of the polymerization initiator or crosslinking agent (curing agent) in the liquid crystal composition is, for example, 0.1 to 10% by weight, preferably 0.5 to 8% by weight, and more preferably 1 to 5% by weight. %. When the content of the polymerization initiator or the crosslinking agent (curing agent) in the liquid crystal composition is less than 0.1% by weight, the desired cholesteric alignment may be insufficiently fixed. On the other hand, when the content of the polymerization initiator or the crosslinking agent (curing agent) in the liquid crystal composition exceeds 10% by weight, the temperature range in which the liquid crystal material exhibits a liquid crystal state becomes narrow, and the cholesteric alignment solidified layer is formed. The temperature must be controlled precisely. This makes it difficult to produce a cholesteric alignment solidified layer, which may lead to a decrease in yield.

  The liquid crystal composition may also contain any appropriate additive as required. Examples of the additive include an anti-aging agent, a modifier, a surfactant, a dye, a pigment, a discoloration inhibitor, and an ultraviolet absorber. These additives may be used alone or in combination of two or more.

  As a method of forming the cholesteric alignment fixed layer used for the second optical compensation layer, any appropriate method can be used as long as a desired cholesteric alignment fixed layer is obtained, for example. Specifically, for example, a step of developing the above liquid crystal composition on a substrate to form a development layer, a step of applying heat treatment to the development layer so that the liquid crystal material in the liquid crystal composition has a cholesteric orientation, A method having a step of solidifying the alignment of the liquid crystal material by subjecting the spreading layer to at least one of a polymerization treatment and a crosslinking treatment, and a step of transferring the solidified layer formed on the substrate can be mentioned.

  This method will be described in more detail. First, a liquid crystal composition containing a liquid crystal material, a chiral agent, a polymerization initiator or a crosslinking agent, and various additives as required is dissolved or dispersed in a solvent to prepare a liquid crystal coating liquid.

  The solvent used in the liquid crystal coating liquid is not particularly limited, and examples thereof include halogenated hydrocarbons, phenols, aromatic hydrocarbons, ketone solvents, ester solvents, alcohol solvents, amide solvents, nitrile solvents. Examples thereof include a solvent, an ether solvent, carbon disulfide, ethyl cellosolve, and butyl cellosolve. Preferred examples include toluene, xylene, mesitylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, cyclohexanone, ethyl cellosolve, butyl cellosolve, ethyl acetate, butyl acetate, propyl acetate, ethyl cellosolve and the like. These solvents may be used alone or in combination of two or more.

  Next, a liquid crystal coating solution is applied onto the substrate to form a spread layer. Examples of the method for forming the spreading layer include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, an extrusion coating method, a curtain coating method, and a spray coating method. A good spin coating method, an extrusion coating method or the like is preferable.

As the substrate on which the liquid crystal coating liquid is developed, for example, various plastic films can be used. Specifically, for example, polyolefin such as triacetyl cellulose (TAC), polyethylene, polypropylene, poly (4-methylpentene-1), or the like is used. Further, the surface of the plastic film such as those forming the SiO ₂ oblique deposition film may be used. The thickness of the substrate is, for example, 5 to 500 μm, preferably 10 to 200 μm, more preferably 15 to 150 μm.

  Next, the spreading layer is subjected to a heat treatment so that the liquid crystal material is aligned in a state showing a liquid crystal phase. Since the spreading layer contains a chiral agent together with the liquid crystal material, the liquid crystal material is oriented with a twist in a state of exhibiting a liquid crystal phase. That is, the development layer shows a cholesteric structure (helical structure).

  Although the temperature of heat processing is based also on the kind of liquid crystal material, it is 40-120 degreeC, for example, Preferably it is 50-100 degreeC, More preferably, it is 60-90 degreeC. Usually, when the temperature of the heat treatment is 40 ° C. or higher, the liquid crystal material can be sufficiently aligned. If the temperature of the heat treatment is 120 ° C. or lower, for example, when considering the heat resistance of the substrate, the range of substrate selection is widened.

  The time for performing the heat treatment is, for example, 30 seconds or more and 10 minutes or less, preferably 1 minute or more and 9 minutes or less, more preferably 2 minutes or more and 8 minutes or less, and even more preferably 4 minutes or more. 7 minutes or less. When the time for performing the heat treatment is shorter than 30 seconds, for example, the liquid crystal material may not be in a sufficient liquid crystal state. On the other hand, when the time for performing the heat treatment is longer than 10 minutes, for example, the additive may be sublimated.

  Next, the orientation (cholesteric structure) of the liquid crystal material is fixed by subjecting the development layer to a polymerization treatment or a crosslinking treatment in a state where the liquid crystal material exhibits a cholesteric structure. Specifically, by performing a polymerization treatment, a liquid crystal material (polymerizable monomer) and / or a chiral agent (polymerizable chiral agent) is polymerized, and the polymerizable monomer and / or polymerizable chiral agent is a repeating unit of a polymer molecule. As fixed. Further, by performing the crosslinking treatment, the liquid crystal material (crosslinkable monomer) and / or the chiral agent forms a three-dimensional network structure, and the crosslinking monomer and / or the chiral agent is fixed as a part of the crosslinked structure. In this way, the alignment state of the liquid crystal material is fixed and becomes a cholesteric alignment solidified layer. A polymer or a three-dimensional network structure formed by polymerizing or crosslinking a liquid crystal material exhibits “non-liquid crystallinity”. Therefore, as described above, the formed cholesteric alignment solidified layer does not cause a phase transition that changes to a liquid crystal phase, a glass phase, or a crystal phase due to, for example, a temperature change specific to liquid crystal molecules.

  The polymerization treatment or the crosslinking treatment varies depending on, for example, the type of polymerization initiator or crosslinking agent used, and is appropriately performed by an appropriate technique. Specifically, for example, when a photopolymerization initiator or a photocrosslinking agent is used, light irradiation may be performed, and when an ultraviolet polymerization initiator or an ultraviolet crosslinking agent is used, ultraviolet irradiation may be performed. What is necessary is just to heat, when using a thermal crosslinking agent.

  The cholesteric alignment solidified layer formed as described above is transferred to the above resin film layer by being bonded with an isocyanate curable adhesive or the like, and becomes a second optical compensation layer made of a laminate. In addition, although the board | substrate which has supported the cholesteric alignment solidified layer becomes a protective film which protects a cholesteric alignment solidified layer, it peels and removes normally at the time of preparation of a polarizing plate.

A-4. Polarizer Any appropriate polarizer may be employed as the polarizer depending on the purpose. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of these polarizers is not particularly limited, but is generally about 1 to 80 μm.

  A polarizer uniaxially stretched by adsorbing iodine to a polyvinyl alcohol film can be produced by, for example, dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing.

  By washing the polyvinyl alcohol film with water, not only can the surface of the polyvinyl alcohol film be cleaned and the anti-blocking agent can be washed, but also the effect of preventing unevenness such as uneven dyeing can be obtained by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

A-5. Protective layer Any appropriate film that can be used as a protective layer of a polarizing plate can be adopted as the protective layer. Specific examples of the material that is the main component of such a film include cellulose resins such as triacetylcellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, Examples thereof include transparent resins such as polysulfone, polystyrene, polynorbornene, polyolefin, acrylic, and acetate. In addition, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film may be an extruded product of the resin composition, for example. TAC, polyimide resin, polyvinyl alcohol resin, and glassy polymer are preferable, and TAC is more preferable.

  The protective layer is preferably transparent and has no color. Specifically, the thickness direction retardation value is preferably −90 nm to +90 nm, more preferably −80 nm to +80 nm, and most preferably −70 nm to +70 nm.

  As the thickness of the protective layer, any appropriate thickness can be adopted as long as the preferable thickness direction retardation is obtained. Specifically, the thickness of the protective layer is preferably 5 mm or less, more preferably 1 mm or less, particularly preferably 1 to 500 μm, and most preferably 5 to 150 μm.

  The protective layer provided on the outer side of the polarizer (on the side opposite to the optical compensation layer) can be subjected to a hard coat treatment, an antireflection treatment, an antisticking treatment, an antiglare treatment, or the like as necessary.

A-6. Polarizing Plate with Optical Compensation Layer Referring to FIG. 1, the first optical compensation layer 12 is disposed between the polarizer 11 and the second optical compensation layer 13. Any appropriate method can be adopted as a method of disposing the first optical compensation layer depending on the purpose. Typically, the first optical compensation layer 12 is provided with a pressure-sensitive adhesive layer (not shown) or an adhesive layer (not shown) on both sides thereof, and the polarizer 11 and the second optical compensation layer 13 are provided. Adhere.

  By filling the gaps between the layers with the pressure-sensitive adhesive layer or the adhesive layer in this way, when incorporated in an image display device, the relationship between the optical axes of the layers is prevented from shifting or the layers are rubbed and damaged. Can be prevented. Further, the interface reflection between layers can be reduced, and the contrast can be increased when used in an image display apparatus.

  The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the purpose of use and the adhesive strength. Specifically, the thickness of the pressure-sensitive adhesive layer is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, and most preferably 10 μm to 30 μm.

  Any appropriate pressure-sensitive adhesive can be adopted as the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. Specific examples include a solvent-type pressure-sensitive adhesive, a non-aqueous emulsion-type pressure-sensitive adhesive, a water-based pressure-sensitive adhesive, and a hot melt pressure-sensitive adhesive. Among these, a solvent-type pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferably used. Appropriate adhesive properties (wetting, cohesiveness and adhesion) for the polarizer, the first optical compensation layer, and the second optical compensation layer, and excellent optical transparency, weather resistance, and heat resistance Because.

  A typical example of the adhesive forming the adhesive layer is a curable adhesive. Typical examples of the curable adhesive include a photocurable adhesive such as an ultraviolet curable adhesive, a moisture curable adhesive, and a thermosetting adhesive.

  Specific examples of the thermosetting adhesive include thermosetting resin adhesives such as epoxy resin, isocyanate resin, and polyimide resin. Specific examples of the moisture curable adhesive include, for example, an isocyanate resin-based moisture curable adhesive. A moisture curable adhesive (especially an isocyanate resin-based moisture curable adhesive) is preferred. Moisture curable adhesives cure by reacting with moisture in the air, adsorbed water on the surface of the adherend, active hydrogen groups such as hydroxyl groups and carboxyl groups, and so on. It can be cured and has excellent operability. Furthermore, since it is not necessary to heat for curing, it is not heated during interlayer adhesion. Therefore, it becomes possible to suppress deterioration of each layer by heating. The isocyanate resin adhesive is a general term for polyisocyanate adhesive, polyurethane resin adhesive, and the like.

  As the curable adhesive, for example, a commercially available adhesive may be used, or the above various curable resins may be dissolved or dispersed in a solvent to prepare a curable resin adhesive solution (or dispersion). Good. When preparing a curable resin adhesive solution (or dispersion), the content of the curable resin in the solution (or dispersion) is preferably 10 to 80% by weight, more preferably 20 to 20% by weight in terms of solid content. It is 65% by weight, more preferably 30-50% by weight. As a solvent to be used, any appropriate solvent can be adopted depending on the type of curable resin. Specific examples include ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene and the like. These may be used alone or in combination of two or more.

The coating amount of the adhesive between the layers can be appropriately set according to the purpose. For example, the coating amount is preferably 0.3 to 3 ml, more preferably 0.5 to ² ml, and still more preferably 1 to ² ml per area (cm ² ) with respect to the main surface of each layer.

  After coating, if necessary, the solvent contained in the adhesive is volatilized by natural drying or heat drying. The thickness of the adhesive layer thus obtained is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and still more preferably 1 to 10 μm.

  The indentation hardness (Microhardness) of the adhesive layer is preferably 0.1 to 0.5 GPa, more preferably 0.2 to 0.5 GPa, and still more preferably 0.3 to 0.4 GPa. In addition, since indentation hardness (Microhardness) has a well-known correlation with Vickers hardness, it can also be converted into Vickers hardness. The indentation hardness (Microhardness) is calculated from the indentation depth and the indentation load using, for example, a thin film hardness meter (for example, trade name: MH4000, trade name: MHA-400, etc.) manufactured by NEC Corporation. be able to.

A-7. Other components of polarizing plate The polarizing plate with an optical compensation layer of the present invention may further include another optical layer. As such another optical layer, any appropriate optical layer may be employed depending on the purpose and the type of the image display device. Specific examples include a liquid crystal film, a light scattering film, a diffraction film, and another optical compensation layer (retardation film).

  The polarizing plate with an optical compensation layer of the present invention may further have a pressure-sensitive adhesive layer or an adhesive layer as an outermost layer on at least one side. Thus, by having a pressure-sensitive adhesive layer or an adhesive layer as the outermost layer, for example, lamination with another member (for example, a liquid crystal cell) is facilitated, and the polarizing plate can be prevented from peeling from the other member. . Any appropriate material can be adopted as the material of the pressure-sensitive adhesive layer. Specific examples of the pressure-sensitive adhesive include those described above. Specific examples of the adhesive include those described above. Preferably, a material excellent in hygroscopicity and heat resistance is used. This is because foaming and peeling due to moisture absorption, deterioration of optical characteristics due to a difference in thermal expansion, and warpage of the liquid crystal cell can be prevented.

  Practically, the surface of the pressure-sensitive adhesive layer or adhesive layer is covered with any appropriate separator until the polarizing plate is actually used, and contamination can be prevented. The separator can be formed by, for example, a method of providing a release coat with a release agent such as silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, or the like on any appropriate film as necessary.

  Each layer in the polarizing plate with an optical compensation layer of the present invention absorbs ultraviolet rays by, for example, treatment with an ultraviolet absorbent such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex salt compound. The ability may be added.

B. Method for Producing Polarizing Plate with Optical Compensation Layer The polarizing plate with an optical compensation layer of the present invention can be produced by laminating each layer via the above-mentioned pressure-sensitive adhesive layer or adhesive layer. Arbitrary appropriate means can be employ | adopted as a lamination | stacking means. For example, the polarizer, the first optical compensation layer, and the second optical compensation layer are punched out to a predetermined size, and the directions are adjusted so that the angle formed by the optical axis of each layer is within a desired range. They can be laminated via an adhesive.

C. Use of polarizing plate with optical compensation layer The polarizing plate with an optical compensation layer of the present invention can be suitably used for various image display devices (for example, liquid crystal display devices, self-luminous display devices). Specific examples of the applicable image display device include a liquid crystal display device, an EL display, a plasma display (PD), and a field emission display (FED). When the polarizing plate with an optical compensation layer of the present invention is used in a liquid crystal display device, it is useful for preventing light leakage and viewing angle compensation in black display, for example. The polarizing plate with an optical compensation layer of the present invention is suitably used for a VA mode liquid crystal display device, and is particularly preferably used for a reflective and transflective VA mode liquid crystal display device. Moreover, when using the polarizing plate with an optical compensation layer of this invention for an EL display, it is useful for electrode reflection prevention, for example.

D. Image Display Device A liquid crystal display device will be described as an example of the image display device of the present invention. Here, a liquid crystal panel used in a liquid crystal display device will be described. As for other configurations of the liquid crystal display device, any appropriate configuration may be adopted depending on the purpose. In the present invention, a VA mode liquid crystal display device is preferable, and reflective and transflective VA mode liquid crystal display devices are particularly preferable. FIG. 2 is a schematic cross-sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. Here, a reflective liquid crystal panel for a liquid crystal display device will be described. The liquid crystal panel 100 includes a liquid crystal cell 20, a retardation plate 30 disposed above the liquid crystal cell 20, and a polarizing plate 10 disposed above the retardation plate 30. Any appropriate retardation plate can be adopted as the retardation plate 30 according to the purpose and the alignment mode of the liquid crystal cell. Depending on the purpose and the alignment mode of the liquid crystal cell, the phase difference plate 30 may be omitted. The polarizing plate 10 is the polarizing plate with an optical compensation layer of the present invention described in the items A and B. The liquid crystal cell 20 includes a pair of glass substrates 21 and 21 'and a liquid crystal layer 22 as a display medium disposed between the substrates. A reflective electrode 23 is provided on the liquid crystal layer 22 side of the lower substrate 21 ′. The upper substrate 21 is provided with a color filter (not shown). A distance (cell gap) between the substrates 21 and 21 ′ is controlled by a spacer 24.

  For example, in the case of the reflective VA mode, in such a liquid crystal display device (liquid crystal panel) 100, liquid crystal molecules are aligned perpendicular to the substrates 21 and 21 'when no voltage is applied. Such vertical alignment can be realized by arranging a nematic liquid crystal having negative dielectric anisotropy between substrates on which a vertical alignment film (not shown) is formed. In this state, when linearly polarized light that has passed through the polarizing plate 10 is incident on the liquid crystal layer 22 from the surface of the upper substrate 21, the incident light travels along the major axis direction of the vertically aligned liquid crystal molecules. . Since birefringence does not occur in the major axis direction of the liquid crystal molecules, incident light travels without changing the polarization direction, is reflected by the reflective electrode 23, passes through the liquid crystal layer 22 again, and is emitted from the upper substrate 21. Since the polarization state of the emitted light is not different from that at the time of incidence, the emitted light is transmitted through the polarizing plate 10 and a bright display is obtained. When a voltage is applied between the electrodes, the major axis of the liquid crystal molecules is aligned parallel to the substrate surface. Liquid crystal molecules exhibit birefringence with respect to linearly polarized light incident on the liquid crystal layer 22 in this state, and the polarization state of incident light changes according to the inclination of the liquid crystal molecules. When a predetermined maximum voltage is applied, the light reflected by the reflective electrode 23 and emitted from the upper substrate becomes, for example, linearly polarized light whose polarization direction is rotated by 90 °, and thus is absorbed by the polarizing plate 10 and is in a dark state. A display is obtained. When the voltage is not applied again, the display can be returned to the bright state by the orientation regulating force. Further, gradation display is possible by changing the intensity of transmitted light from the polarizing plate 10 by changing the applied voltage to control the inclination of the liquid crystal molecules.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited by these Examples.

[Example 1]
(Production of polarizer)
A commercially available polyvinyl alcohol (PVA) film (manufactured by Kuraray Co., Ltd.) is dyed in an aqueous solution containing iodine, and then uniaxially stretched about 6 times between rolls having different speed ratios in an aqueous solution containing boric acid. A polarizer was obtained. A commercially available TAC film (manufactured by Fuji Photo Film Co., Ltd.) was bonded to both sides of this polarizer using a PVA adhesive to obtain a polarizing plate (protective layer / polarizer / protective layer) having a total thickness of 100 μm. This polarizing plate was punched into a length of 20 cm × width of 30 cm. At this time, the absorption axis of the polarizer was set in the vertical direction.

(Preparation of the first optical compensation layer)
A modified polycarbonate film having a thickness of 77 μm (manufactured by Teijin Ltd., trade name: Pure Ace WR) that has already been stretched was used as the first film for the optical compensation layer. This film has a refractive index distribution of nx> ny = nz, shows a wavelength dispersion characteristic that a retardation value which is an optical path difference between extraordinary light and ordinary light becomes smaller as the wavelength becomes shorter, and an in-plane retardation thereof. Re ₁ was 147 nm. This film was punched into a length of 20 cm and a width of 30 cm to form a first optical compensation layer. At this time, the slow axis was set to the vertical direction.

(Preparation of second optical compensation layer)
A norbornene-based resin film (manufactured by JSR, trade name Arton, thickness 100 μm) is longitudinally stretched 1.27 times at 175 ° C. and then transversely stretched 1.37 times at 176 ° C., so that nx = ny> nz A long second film for optical compensation layer (thickness: 65 μm) having a refractive index distribution of 5 mm was prepared. This film was punched into a length of 20 cm and a width of 30 cm to form a second optical compensation layer. The in-plane retardation Re ₂ of the second optical compensation layer was 0 nm, and the thickness direction retardation Rth ₂ was 110 nm.

(Preparation of polarizing plate with optical compensation layer)
The obtained polarizing plate, the first optical compensation layer, and the second optical compensation layer were laminated in this order. The first optical compensation layer was laminated so that the slow axis was 45 ° counterclockwise with respect to the absorption axis of the polarizer of the polarizing plate. The polarizing plate and the first optical compensation layer, and the first optical compensation layer and the second optical compensation layer were laminated using an acrylic adhesive (thickness: 20 μm). Next, the laminated film was punched into a length of 4.0 cm and a width of 5.3 cm to obtain a polarizing plate (1) with an optical compensation layer.

[Example 2]
In Example 2, instead of the norbornene resin film used in Example 1, a laminate of a cholesteric alignment solidified layer and a resin film having the following configuration was used as a second optical compensation layer serving as a negative C plate. . Specifically, the second optical compensation layer in Example 2 was produced as follows.

(Preparation of second optical compensation layer)
90 parts by weight of a nematic liquid crystalline compound represented by the following formula (10), 10 parts by weight of a chiral agent represented by the following formula (38), 5 parts by weight of a photopolymerization initiator (Irgacure 907: manufactured by Ciba Specialty Chemicals), and 300 parts by weight of methyl ethyl ketone was mixed uniformly to prepare a liquid crystal coating solution. Next, this liquid crystal coating solution is coated on a substrate (biaxially stretched PET film), heat-treated at 80 ° C. for 3 minutes, and then subjected to polymerization treatment by irradiating with ultraviolet rays to form a cholesteric alignment solidified layer (thickness 2 μm). did.

Next, an isocyanate curable adhesive (thickness 5 μm) is applied to the cholesteric alignment solidified layer, and a resin film layer (TAC film: manufactured by Konica Corporation: thickness) having a relationship of nx = ny> nz through this adhesive. 40 μm) to form a second optical compensation layer made of a laminate of a cholesteric alignment solidified layer and a resin film layer. The substrate (biaxially stretched PET film) on which the cholesteric alignment solidified layer was supported was peeled off and removed at the time of preparing the polarizing plate. The total thickness of the obtained second optical compensation layer was 47 μm, the in-plane retardation Re ₂ was 0 nm, and the thickness direction retardation Rth ₂ was 160 nm.

(Preparation of polarizing plate with optical compensation layer)
A polarizing plate (2) with an optical compensation layer was prepared in the same manner as in Example 1 except that the second optical compensation layer comprising a laminate of a cholesteric alignment solidified layer and a resin film produced as described above was used. Obtained. When obtaining the polarizing plate with an optical compensation layer, the resin film layer of the second optical compensation layer was made to face the first optical compensation layer.

[Comparative Example 1]
(Preparation of the first optical compensation layer)
By uniaxially stretching a norbornene resin film (manufactured by Nippon Zeon Co., Ltd .: trade name ZEONOR: thickness 60 μm: photoelastic coefficient 3.10 × 10 ⁻¹² m ² / N) at 140 ° C. by 1.32 times, nx> ny A long first optical compensation layer film (thickness: 50 μm) having a refractive index distribution of = nz was prepared. This film was punched into a length of 20 cm and a width of 30 cm to form a first optical compensation layer. The in-plane retardation Re ₁ of the first optical compensation layer was 140 nm. This first optical compensation layer exhibited chromatic dispersion characteristics in which the in-plane retardation Re ₁ was almost flat regardless of the wavelength.

(Preparation of polarizing plate with optical compensation layer)
A polarizing plate (C1) with an optical compensation layer was obtained in the same manner as in Example 1 except that the first optical compensation layer obtained above was used.

[Comparative Example 2]
In Comparative Example 2, a laminated compensation layer obtained by further laminating a first ′ optical compensation layer having an in-plane retardation Re of about 270 nm on the first optical compensation layer of Comparative Example 1 was used as the first optical compensation layer. .

(Preparation of 1 'optical compensation layer)
By uniaxially stretching a norbornene resin film (manufactured by Nippon Zeon Co., Ltd .: trade name ZEONOR: thickness 60 μm: photoelastic coefficient 3.10 × 10 ⁻¹² m ² / N) at 140 ° C. by 1.90 times, nx> ny A long first optical compensation layer film (having a thickness of 45 μm) having a refractive index distribution of = nz was prepared. This film was punched into a length of 20 cm × width of 30 cm to form a first ′ optical compensation layer. The in-plane retardation Re ₁ ′ of the first ′ optical compensation layer was 270 nm.

(Preparation of polarizing plate with optical compensation layer)
The same polarizing plate as in Example 1, the first ′ optical compensation layer produced as described above, the first optical compensation layer similar to Comparative Example 1, and the second optical compensation layer similar to Example 1 The layers were laminated in this order. Here, the first ′ optical compensation layer and the first optical compensation layer are laminated so that the slow axes thereof are 15 ° and 75 ° counterclockwise with respect to the slow axis of the polarizer of the polarizing plate, respectively. did. Next, the polarizing plate, the first ′ optical compensation layer, the first optical compensation layer, and the second optical compensation layer were laminated with an acrylic pressure-sensitive adhesive (thickness: 20 μm). Next, the laminated film was punched into a length of 4.0 cm and a width of 5.3 cm to obtain a polarizing plate (C2) with an optical compensation layer. The in-plane retardation Re ₁ of the laminated first optical compensation layer was 138 nm.

  Table 1 shows embodiments of lamination in each of the polarizing plates with optical compensation layers.

[Evaluation 1: Viewing angle characteristics]
The polarizing plate with an optical compensation layer of Example or Comparative Example obtained as described above was applied to a VA mode liquid crystal cell (Sharp mobile phone, model number: SH901iS) through an acrylic adhesive (thickness 20 μm). It laminated | stacked on the visual recognition side glass substrate side. At this time, the glass substrate and the second optical compensation layer were bonded so as to face each other. In this way, a VA mode liquid crystal display device was obtained. About the VA mode liquid crystal cell in which the polarizing plate with an optical compensation layer was mounted, the viewing angle characteristic was measured using a viewing angle characteristic measuring device (EZ Contrast manufactured by ELDIM). FIG. 3 shows a contrast contour map as a measurement result.

  It can be seen that the viewing angle of the liquid crystal cell using the polarizing plate with the optical compensation layer of the example is significantly wider than that of the liquid crystal cell using the polarizing plate with the optical compensation layer of the comparative example.

  The polarizing plate with an optical compensation layer of the present invention can be suitably used for various image display devices (for example, liquid crystal display devices, self-luminous display devices).

It is a schematic sectional drawing of the polarizing plate with an optical compensation layer by preferable embodiment of this invention. It is a schematic sectional drawing of the liquid crystal panel used for the liquid crystal display device by preferable embodiment of this invention. (A), (b), (c), and (d) are a liquid crystal panel using the polarizing plate with optical compensation layer (1) of Example 1, and the polarizing plate with optical compensation layer of Example 2 (2). ), A liquid crystal panel using the polarizing plate with optical compensation layer (C1) of Comparative Example 1, and a liquid crystal panel using the polarizing plate with optical compensation layer (C2) of Comparative Example 2 is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polarizing plate with optical compensation layer 11 Polarizer 12 First optical compensation layer 13 Second optical compensation layer 20 Liquid crystal cell 100 Liquid crystal panel

Claims (12)

Having a polarizer, a first optical compensation layer, and a second optical compensation layer in this order;
First optical compensation layer, nx> ny = has a refractive index profile of nz, shows the wavelength dispersion characteristic in-plane retardation Re ₁ decreases toward the shorter wavelength side, and an in-plane retardation Re ₁ Is 90 to 160 nm,
The second optical compensation layer is a film layer, has a refractive index distribution of nx = ny> nz, has an in-plane retardation Re ₂ of 0 to ₂₀ nm, and has a thickness direction retardation Rth. ₂ is 30 to 300 nm,
Polarizing plate with optical compensation layer.   The polarizing plate with an optical compensation layer according to claim 1, wherein the first optical compensation layer is a stretched film layer and includes a polycarbonate having a fluorene skeleton.   The polarizing plate with an optical compensation layer according to claim 1, wherein the first optical compensation layer is a stretched film layer and contains cellulose acetate.   The polarizing plate with an optical compensation layer according to claim 1, wherein the first optical compensation layer is a stretched film layer and contains two or more types of aromatic polyester polymers having different wavelength dispersion characteristics.   2. The optical device according to claim 1, wherein the first optical compensation layer is a stretched film layer and includes a copolymer having two or more types of monomer units derived from a monomer that forms a polymer having different wavelength dispersion characteristics. A polarizing plate with a compensation layer.   The polarizing plate with an optical compensation layer according to claim 1, wherein the first optical compensation layer is a composite film layer in which two or more kinds of stretched film layers having different wavelength dispersion characteristics are laminated.   The polarizing plate with an optical compensation layer according to any one of claims 1 to 6, wherein the second optical compensation layer contains a cyclic olefin-based resin and / or a cellulose-based resin. The second optical compensation layer has a cholesteric alignment solidified layer having a selective reflection wavelength region of 350 nm or less, a refractive index distribution of nx = ny> nz, and an absolute value of the photoelastic coefficient is 2 × 10 ^−11. The polarizing plate with an optical compensation layer according to claim 1, which has a layer made of a film containing a resin of m ² / N or less.   A liquid crystal panel comprising the polarizing plate with an optical compensation layer according to claim 1 and a liquid crystal cell.   The liquid crystal panel according to claim 9, wherein the liquid crystal cell is a reflective or transflective VA mode.   A liquid crystal display device comprising the liquid crystal panel according to claim 9.   An image display device comprising the polarizing plate with an optical compensation layer according to claim 1.

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