JP2009288312A - Optical element and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of preventing change of color tone due to change of polar angle in the direction of observation and making manners of change of color tone equal in a right-and-left symmetrical azimuth angle on a display surface and to provide an optical element capable of constituting the liquid crystal display device. <P>SOLUTION: This optical element has at least first polarizer, a first 1/4λ plate, and a resin layer having the first cholesteric regularity in this order. In this optical element, the center in a selective reflection band of front incident light in the resin layer having the first cholesteric regularity is 495 nm or less or 620 nm or more. The liquid crystal display device includes this optical element. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical element and a liquid crystal display device.

  The liquid crystal display device usually includes a light source, two dichroic polarizers, and a liquid crystal cell disposed between the dichroic polarizers. An image is displayed by controlling whether or not it can be transmitted by a liquid crystal cell. The behavior of light transmitted through the two dichroic polarizers is different between light having a polar angle of 0 ° (that is, a direction perpendicular to the display surface) and light having a polar angle inclined from 0 °. The degree of such difference differs depending on the wavelength of light. As a result, the hue of the color image when observed from the front and the hue of the color image when observed from an oblique direction are undesirably different.

  In a liquid crystal display device, a reflective polarizer may be used to improve luminance. In the reflective polarizer, the selective reflection band of light incident from an oblique direction is shifted to the short wavelength side compared to the selective reflection band of light incident from a polar angle of 0 °. Even with a reflective polarizer that can reflect the entire visible light region with respect to light incident from the front, long wavelength light (red light) may not be reflected with respect to light incident from an oblique direction. For this reason, in general, in a liquid crystal display device, the color image when viewed from the front is different from the color image when viewed from an oblique direction.

  In order to eliminate the difference in hue depending on the observation angle, for example, as described in Patent Documents 1 and 2, it is proposed to arrange a layer obtained by polymerizing a composition exhibiting a cholesteric liquid crystal phase. However, when such a layer is disposed, the amount of light incident obliquely decreases.

Furthermore, when such a layer is disposed, the viewing angle characteristics on the left and right sides of the display surface become asymmetrical based on the asymmetry of the cholesteric liquid crystal phase.
For example, as shown in FIGS. 3 and 4, when the liquid crystal display device 301 in a vertically standing state is observed, the polar angle of the observation angle (that is, the observation angle when the direction D310 perpendicular to the display surface is 0 °) The inclination of the polar angle is symmetrical in the left-right direction (x-axis direction in the figure) about the vertical line (y-axis direction in the figure) of the display surface. It is desirable to be. More specifically, the magnitude of the polar angle θ321 tilted in the direction (A321) of 45 ° and the polar angle θ321 toward the azimuth angle (angle in which the right direction is 0 ° toward the display surface and the left rotation is the + direction). The relationship between the change in color tone when observed from the direction D321 of the image is the relationship between the magnitude of the polar angle θ322 inclined in the direction (A322) with the azimuth angle of 135 ° and the change in color tone when observed from the direction D322 of the polar angle θ322. Is preferably equal to However, when a liquid crystal display device is arranged by polymerizing a composition exhibiting a cholesteric liquid crystal phase between a display surface and a light source, these relationships are not equal due to the asymmetry of the cholesteric liquid crystal phase.

JP 2002-169026 A JP 2004-309618 A

  An object of the present invention is to provide a liquid crystal display device in which a change in color tone due to a change in polar angle in the viewing direction is small and the mode of change in the color tone is the same in a symmetric azimuth angle on the display surface, and such a liquid crystal display device. It is an object of the present invention to provide an optical element capable of providing

As a result of intensive studies to solve this problem, the present inventors have found that the above problem can be solved by arranging a resin layer having a specific cholesteric regularity in combination with a 1 / 4λ plate. The invention has been completed.
Thus, the present invention includes the following.

[1] An optical element having at least a first polarizer, a first ¼λ plate, and a resin layer having a first cholesteric regularity in this order, the resin layer having the first cholesteric regularity The center of the selective reflection band of the front incident light is 495 nm or less or 620 nm or more.
[2] A second 1 / 4λ plate is further provided outside the resin layer having the first cholesteric regularity, and the slow axis of the second 1 / 4λ plate is the first 1 / 4λ. The optical element according to claim 1, wherein the optical element is in a direction perpendicular to a slow axis of the plate.
[3] The optical element, wherein the first polarizer, the first 1 / 4λ plate, and the resin layer having the first cholesteric regularity are integrated.
[4] A second cholesteric regularity is provided between the first ¼λ plate and the resin layer having the first cholesteric regularity or outside the resin layer having the first cholesteric regularity. The resin layer having the second cholesteric regularity has a selective reflection performance in a region of at least 480 to 620 nm with respect to the front incident light, and the resin layer having the first cholesteric regularity The optical element according to claim 2, wherein the twist direction of molecules of the resin layer having the second cholesteric regularity is reverse.
[5] The optical element, wherein an absorption axis of the first polarizer and an optical axis of the first ¼λ plate form an angle of about 45 °.
[6] A liquid crystal display device having at least a second polarizer, a liquid crystal cell, a first polarizer, a first ¼λ plate, a resin layer having a first cholesteric regularity, and a light source in this order. The liquid crystal display device characterized in that the center of the selective reflection band of front incident light of the resin layer having the first cholesteric regularity is 495 nm or less or 620 nm or more.
[7] A second 1 / 4λ plate is further provided between the resin layer having the first cholesteric regularity and the light source, and a slow axis of the second 1 / 4λ plate is the first slow axis. The liquid crystal display device is in a direction perpendicular to the slow axis of the 1 / 4λ plate.
[8] The liquid crystal display device, wherein the first polarizer, the first ¼λ plate, and the resin layer having the first cholesteric regularity are integrated.
[9] Between the first 1 / 4λ plate and the resin layer having the first cholesteric regularity, or between the resin layer having the first cholesteric regularity and the light source, a second A resin layer having cholesteric regularity, wherein the second cholesteric regular resin layer has selective reflection performance in a region of at least 480 to 620 nm with respect to front incident light, and the first cholesteric regularity The liquid crystal display device according to claim 1, wherein the twist direction of molecules of the resin layer having the resin layer and the resin layer having the second cholesteric regularity is opposite.
[10] The liquid crystal display device, wherein an absorption axis of the first polarizer and an optical axis of the first ¼λ plate form an angle of about 45 °.

  In the liquid crystal display device having the optical element of the present invention, a change in color tone due to a change in polar angle in the observation direction is suppressed by the resin layer having the first cholesteric regularity, and the change in the color tone on the display surface is affected. Therefore, it is useful as a liquid crystal display device with a wide viewing angle.

In the following, the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a perspective view schematically showing a first embodiment of a liquid crystal display device of the present invention having the optical device of the present invention. The upper side of the liquid crystal display device shown in FIG. 1 is a display surface. If the display device of this embodiment is used with its display surface upright as shown in FIG. 3, the x-axis and y-axis shown in the figure correspond to the horizontal and vertical directions of the screen, and the z-axis is the display surface. It corresponds to the normal direction.
The apparatus of the first embodiment includes a second polarizer 11, a liquid crystal cell 12, a first polarizer 13, a first ¼λ plate 17, a resin having a first cholesteric regularity (hereinafter referred to as “cholesteric”). A layer 18 and a light source 19, of which the first polarizer 13, the first ¼λ plate 17, and the first cholesteric resin layer 18 are the optical elements of the present invention. Configure the element. The apparatus according to the present embodiment further includes, as an optional component, a reflecting plate 20 that reflects light from the light source toward the display surface on the side opposite to the display surface with the light source 19 interposed therebetween. Each component has dimensions that match the rectangular shape of the display surface.

(Polarizer and liquid crystal cell)
The second polarizer 11, the liquid crystal cell 12, and the first polarizer 13 are not particularly limited, and those used in known liquid crystal display devices can be appropriately selected. Specifically, the polarized light that has been transmitted through the first polarizer 13 is controlled by the liquid crystal cell 12 so as to be transmitted through the second polarizer 11 and emitted from the display surface or not from the display surface. As a result, an image is displayed on the display surface. Various types of displayed liquid crystal cells and polarizers can be used. As a driving method of the liquid crystal cell, for example, a TN (Twisted Nematic) type, an STN (Super Twisted Nematic) type, a HAN (Hybrid Alignment Nematic) type, an IPS (In Plane Switching) type, a VA (vertical type), and a VA (vertical type) Multiple Vertical Alignment type, OCB (Optical Compensated Bend) type, etc. are mentioned.

  As the polarizer, a normal linear polarizer, that is, one that transmits some linearly polarized light and absorbs or reflects other light can be used. Although the polarization degree of the polarizer used for this invention is not specifically limited, Preferably it is 98% or more, More preferably, it is 99% or more. The average thickness of the polarizer is preferably 5 to 80 μm.

  Examples of the polarizer include those obtained by adsorbing iodine or dichroic dye on a polyvinyl alcohol film and then uniaxially stretching in a boric acid bath, or iodine or dichroic dye on a polyvinyl alcohol film. Examples thereof include those obtained by adsorbing and stretching, and further modifying a part of the polyvinyl alcohol unit in the molecular chain into a polyvinylene unit.

  In the present invention, the polarizer may be disposed together with a substrate and / or a protective film for protecting the polarizer from damage or moisture. The substrate is not particularly limited, and a substrate that can transmit arbitrary light, such as a glass substrate, can be used. As the protective film for covering the polarizer, cellulose diacetate, cellulose triacetate, alicyclic olefin polymer, acrylic resin, polycarbonate resin, polyethersulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polyethylene methacrylate A film containing a thermoplastic resin such as a resin, a polysulfone resin, a polyethylene resin, a polystyrene resin, or a polyvinyl chloride resin can be used.

(First 1 / 4λ plate)
The first quarter λ plate 17 can have a retardation Re (hereinafter sometimes abbreviated as “Re”) in the front direction to be substantially a quarter wavelength of transmitted light. Here, the wavelength range of the transmitted light can be a desired range displayed by the apparatus of the present invention, and specifically, for example, 400 nm to 700 nm. Further, the retardation Re in the front direction is approximately ¼ wavelength of transmitted light, and the Re value is ± 65 nm from the ¼ value of the center value in the center value of the wavelength range of transmitted light, preferably It means ± 30 nm, more preferably ± 10 nm.

Here, the retardation Re in the front direction is represented by the formula I: Re = (nx−ny) × d (where nx is a direction perpendicular to the thickness direction (in-plane direction)) and gives the maximum refractive index. Ny represents a refractive index in a direction perpendicular to the thickness direction (in-plane direction) and orthogonal to nx, and d represents a film thickness.
In addition, the retardation Re in the front direction is obtained by using a commercially available phase difference measuring apparatus to separate the optically anisotropic element at 100 mm intervals in the longitudinal direction and the width direction (when the length in the longitudinal direction or the lateral direction is less than 200 mm). Are specified at equal intervals in that direction), and are measured in the form of lattice points over the entire surface to obtain the average value.

  In the present invention, the thickness of the first 1 / 4λ plate is preferably 50 to 1000 μm, more preferably 50 to 600 μm.

  In the present invention, the absorption axis of the first polarizer and the optical axis of the first ¼λ plate preferably form an angle of about 45 °. Here, the optical axis of the 1 / 4λ plate is the nx direction. Moreover, substantially 45 degrees is an angle within the range of 35-55 degrees. When the axis forms such an angle, it is possible to achieve a reduction in the left-right asymmetry of the viewing angle characteristics of the good display surface.

  The material constituting the 1 / 4λ plate having the above characteristics and the manufacturing method thereof will be described in detail later.

(First cholesteric resin layer)
The first cholesteric resin layer 18 is made of a resin having cholesteric regularity.
In the present invention, the cholesteric regularity possessed by the cholesteric resin is such that the molecular axes are arranged in a certain direction on one plane, but the direction of the molecular axes is slightly offset on the next plane, and further on the next plane. In addition, the angle of the molecular axis is shifted (twisted) one after another in the normal direction of the plane, such that the angle is further shifted.

  Thus, the structure in which the direction of the molecular axis is twisted becomes an optically chiral structure. The helical axis that is the normal line of the plane is preferably substantially parallel to the thickness direction of the cholesteric resin layer.

  The structure of an example of the 1st cholesteric resin layer in this invention is shown in FIG. The cholesteric resin layer 3 shown in FIG. 2 can be obtained by forming the alignment film 2 on the sheet-like transparent substrate 1 and further forming the cholesteric resin layer 3 thereon, and the helical pitches P0 to P3 are obtained. Have. The helical pitch is a distance in the direction of the helical axis until the molecular axis direction gradually shifts in the cholesteric liquid crystal phase as it advances along the helical axis and then returns to the original molecular axis direction again. The helical pitch may be uniform or nonuniform in the resin layer.

  The cholesteric resin layer selectively reflects transmitted light in a band corresponding to the helical pitch. That is, the light incident on the cholesteric resin layer at the polar angle θ1 is refracted and the polar angle in the traveling direction is changed to θ2, and then either clockwise or counterclockwise circularly polarized light having a wavelength corresponding to the helical pitch. Is reflected and the rest is transmitted. In the cholesteric resin layer, the selective reflection band tends to shift to the short wavelength side as the polar angle in the incident direction of transmitted light increases.

(Selective reflection band of the first cholesteric resin layer and its relationship with the light source wavelength)
In the present invention, the center of the selective reflection band of the front incident light of the first cholesteric resin layer is (a) 495 nm or less, or (b) 620 nm or more.

  In the case of (a), the center of the selective reflection band can be preferably in the range of 395 to 495 nm. The width of the selective reflection band is preferably 30 to 200 nm as a half width.

  In the case of (a), the light source 19 preferably has a light emitting region in both a region having a wavelength of 495 nm or less and a region having a wavelength exceeding 495 nm. The center of the selective reflection band of the first cholesteric resin layer is preferably configured so as to be away from the emission peak of the light source 19 in the region of 495 nm or less as the incident angle of the transmitted light increases. Specifically, for example, the emission peak of the light source 19 preferably exists in the range of +100 nm to −50 nm from the center wavelength of the selective reflection band of the front incident light of the first cholesteric resin layer. By adopting such a configuration, the proportion of the light component on the short wavelength side of the light transmitted through the first cholesteric resin layer is increased as the polar angle in the observation direction increases, and as a result, the polar angle is increased. It is possible to correct the redness of the device display surface as the size increases.

  On the other hand, in the case of (b), the center of the selective reflection band can be preferably in the range of 620 to 820 nm. The width of the selective reflection band is preferably 30 to 200 nm as a half width.

  In the case of (b), the light source 19 preferably has a light emitting region in both a region having a wavelength of 620 nm or more and a region having a wavelength of less than 620 nm. The center of the selective reflection band of the first cholesteric resin layer is preferably configured to approach the emission peak of the light source 19 in the region of 620 nm or more as the incident angle of the transmitted light increases. Specifically, for example, it is preferable that the emission peak of the light source 19 exists in the range of +0 nm to −200 nm from the center wavelength of the selective reflection band of the front incident light of the first cholesteric resin layer. By adopting such a configuration, it is possible to reduce the proportion of the light component on the long wavelength side of the light transmitted through the first cholesteric resin layer as the polar angle in the observation direction increases, and as a result, As the polar angle increases, the device display surface can be corrected to be reddish.

  In the present invention, the thickness of the first cholesteric resin layer after drying is preferably 0.5 μm to 10.0 μm, more preferably 1.0 to 8 μm. By setting the film thickness after drying to 0.5 μm or more, sufficient reflectance can be easily obtained, and by setting it to 10.0 μm or less, coloring when observed from an oblique direction with respect to the cholesteric resin layer is prevented. It is preferable to do. In addition, when the first cholesteric resin layer is formed by laminating two or more layers, the dry film thickness is the sum of the film thicknesses of the respective layers, and when the cholesteric resin layer is one layer, Refers to the film thickness.

  The material constituting the cholesteric resin layer having the above characteristics and the manufacturing method thereof will be described in detail later.

(light source)
The light source 19 can be a cold cathode tube, a hot cathode tube, a light emitting diode, or a combination thereof, and preferably includes a cold cathode tube.

  In the present invention, it is preferable that the light source 19 has two or more light emitting regions suitable for the selective reflection band of the first cholesteric resin layer as described above. Here, the emission region is a wavelength band in which light emission is observed when an emission spectrum is observed. Here, when the light source is a combination of a plurality of types, the light emission region in the spectrum of all the combined light sources can be set as the specific light emission region.

  The light emitted from the light source 19 enters the first cholesteric resin layer 18 directly or after being reflected by the reflecting plate 20. Here, the transmitted light is corrected so that the incident light having a higher polar angle has a relatively large amount of light on the short wavelength side, and further transmitted through the first ¼λ plate 17. The combination of the first cholesteric resin layer 18 and the first ¼λ plate 17 reduces the left-right asymmetry of the viewing angle characteristics of the display surface. That is, the polar angle in the observation direction is determined in the azimuth angle (for example, 45 ° direction and 135 ° direction) symmetrical with respect to the vertical y-axis as shown in FIGS. There can be little difference in the relationship with the change in transmittance.

  In FIG. 1, each component is shown separately for the sake of illustration, but at least layers other than the light source and the reflector among these devices can be provided in contact with each other in the device. These components may be provided integrally.

  Such integration can be achieved, for example, by adhering a certain layer and another layer through another layer such as an adhesive layer, or by using a material such as a resin that constitutes a certain layer. It can also be achieved by obtaining a structure in which two layers are laminated by applying a coating layer on this layer to form a coating layer and curing the coating layer.

  In the present embodiment, it is particularly preferable that the first polarizer 13, the first ¼λ plate 17, and the first cholesteric resin layer 18 are integrated. With such an integrated configuration, a reduction in the amount of light due to reflection at the interface of each layer can be reduced, and the device can be easily manufactured.

  Moreover, the 2nd polarizer 11, the liquid crystal cell 12, and the 1st polarizer 13 can also be integrated, and this integration can be achieved by various known methods.

(Second Embodiment)
FIG. 5 is a perspective view schematically showing a second embodiment of the optical element and the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 5 is different from the first embodiment in that it further includes a second ¼λ plate 21 between the first cholesteric resin layer 18 and the light source 19.

  Thus, in the embodiment having the first and second quarter λ plates with the first cholesteric resin layer interposed therebetween, the slow axis of the second quarter λ plate 21 is the first quarter λ. It is preferable to be in a direction perpendicular to the slow axis of the plate 17. For example, a mode in which the slow axis of the first 1 / 4λ plate 17 is in the x-axis direction and the slow axis of the second 1 / 4λ plate 18 is in the y-axis direction is preferable. By setting it as such an aspect, the left-right asymmetry of the viewing angle characteristic of a display surface can further be reduced. Further, even when the second quarter λ plate 21 is disposed between the brightness enhancement film (trade name DBEF manufactured by 3M Co., Ltd.) and the polarizer, the left-right asymmetry of the viewing angle characteristic can be reduced.

  The second quarter λ plate 21 can have a retardation Re in the front direction (hereinafter sometimes abbreviated as “Re”) of approximately ¼ wavelength of transmitted light. Here, the wavelength range of the transmitted light can be a desired range displayed by the apparatus of the present invention, and specifically, for example, 400 nm to 700 nm. Further, the retardation Re in the front direction is approximately ¼ wavelength of the transmitted light means that the Re value is ± 65 nm from the ¼ value of the center value in the center value of the wavelength range of the transmitted light, preferably It means ± 30 nm, more preferably ± 10 nm.

  In the present invention, the thickness of the second 1 / 4λ plate is preferably 50 to 1000 μm, more preferably 50 to 600 μm.

(Third embodiment)
FIG. 6 is a perspective view schematically showing a third embodiment of the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 6 is different from the first embodiment in that a second cholesteric resin layer 22 is provided between the first cholesteric resin layer 18 and the light source 19.

  Here, the second cholesteric resin layer 22 has selective reflection performance in the region of at least 480 to 620 nm with respect to the front incident light, and further, the molecules of the first cholesteric resin layer 18 and the second cholesteric resin layer 22 The twist direction is the reverse direction. By combining the second cholesteric resin layer in such a manner, the left-right asymmetry of the viewing angle characteristics of the display surface can be further reduced while improving the luminance by the second cholesteric resin layer.

Here, “having selective reflection performance” means that the maximum transmittance in the visible light range of 380 to 780 nm is a [%], the minimum transmittance is b [%], and the transmittance at a certain wavelength (λ) is the transmittance. When (λ) [%]:
{A-transmittance (λ)} / {ab} ≧ 0.3
It is to make it the wavelength range which satisfies. “To have selective reflection performance in the region of at least 480 to 620 nm with respect to the front incident light” means that the transmittance satisfies the condition in at least the region of λ = 480 to 620 nm. The lower limit of the region having selective reflection performance is more preferably 400 nm, even more preferably 350 nm, and the upper limit of the region having selective reflection performance is more preferably 800 nm, and even more preferably 900 nm. By having such selective reflection performance, it is possible to obtain an effect such as improvement in luminance in a wide reflection band.

  In the present invention, the thickness of the second cholesteric resin layer after drying is preferably 3.0 μm to 10.0 μm, more preferably 3.5 to 8 μm. By setting the film thickness after drying to 3.0 μm or more, sufficient reflectance can be easily obtained, and by setting the film thickness to 10.0 μm or less, coloring when observed from an oblique direction with respect to the cholesteric resin layer is prevented. It is preferable to do. In addition, when the first cholesteric resin layer is formed by laminating two or more layers, the film thickness after drying is the sum of the film thicknesses of the respective layers when the cholesteric resin layer is one layer. Indicates the film thickness.

(Other embodiments)
In the embodiment described above, the second cholesteric resin layer 22 is provided between the first cholesteric resin layer 18 and the light source 19, but the arrangement of the second cholesteric resin layer is not limited thereto, For example, it can be arranged between the first ¼λ plate 17 and the first cholesteric resin layer 18.

  Further, in the form in which the first polarizer 13, the first ¼λ plate 17, and the first cholesteric resin layer 18 are integrated, the second ¼λ plate or the second cholesteric resin is further provided. It is also possible to provide layers and integrate them. By adopting such an integrated configuration, it is possible to reduce the amount of light due to reflection at the interface of each layer while obtaining the effects of these additional components, and to facilitate the manufacture of the device. . The second quarter λ plate or the second cholesteric resin layer is preferably integrated with the first cholesteric resin layer or the like via an adhesive layer or the like, thereby reducing the amount of light due to reflection at the interface of each layer. Further reductions can be made and the manufacture of the device can be made easier.

(Other components)
In addition to the above configuration, the optical element of the present invention and the liquid crystal display device of the present invention can further optionally include other components. For example, a configuration for driving a liquid crystal cell, a color filter, a configuration for driving a light source, a diffusion plate that diffuses light before the light from the light source enters the optical element, and other normal liquid crystal display devices Any component can be included as appropriate.
(Use)
The use of the liquid crystal display device of the present invention having the optical element of the present invention is not particularly limited, and can be used as a television, a display device for computers, a display device for other electronic devices, and the like.

(Materials and forming methods for each layer)
Next, the materials and forming methods of the quarter λ plate and the cholesteric resin layer constituting the optical element and the liquid crystal display device of the present invention will be described in more detail.

(Material of 1 / 4λ plate and forming method)
As the quarter λ plate used in the present invention, (i) a film-like polymer stretched or (ii) a liquid crystal material coated on a transparent resin substrate, oriented and cured is used. be able to. In the case of using the (ii) 1 / 4λ plate, a liquid crystal material is applied on an appropriate base material, oriented, and cured to obtain a 1 / 4λ plate.

  As a preferable example of the quarter λ plate used in the present invention, an optically anisotropic element formed by stretching a resin film made of the above-mentioned (i), particularly an alicyclic olefin polymer, and a resin film including a styrene resin layer are used. An optically anisotropic element formed by stretching can be mentioned.

  The optically anisotropic element preferably has a laminated structure of a layer made of the styrene resin and a layer containing another thermoplastic resin. By having the laminated structure, it is possible to provide an element that has both the optical characteristics of the styrene resin and the mechanical strength of other thermoplastic resins. Other thermoplastic resins include alicyclic olefin polymers, methacrylic resins, polycarbonates, acrylic ester-vinyl aromatic compound copolymer resins, methacrylic ester-vinyl aromatic compound copolymer resins, polyethersulfone, etc. Can be mentioned. Among these, a resin having an alicyclic structure or a methacrylic resin can be preferably used.

  The alicyclic olefin polymer is an amorphous olefin polymer having a cycloalkane structure or a cycloalkene structure in the main chain and / or side chain. Specifically, (1) norbornene polymer, (2) monocyclic olefin polymer, (3) cyclic conjugated diene polymer, (4) vinyl alicyclic hydrocarbon polymer, and these A hydride etc. are mentioned. Among these, norbornene-based polymers are more preferable from the viewpoints of transparency and moldability. Examples of the resin having these alicyclic structures include those described in JP-A No. 05-310845, JP-A No. 05-097978, and US Pat. No. 6,511,756.

  Specific examples of the norbornene-based polymer include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers capable of ring-opening copolymerization, hydrides thereof, and norbornene-based monomers. And addition copolymers with other monomers copolymerizable with norbornene monomers.

  Methacrylic resin is a polymer containing methacrylic acid ester as the main raw material component, and includes methacrylic acid ester homopolymers and copolymers of methacrylic acid esters and other monomers. Usually, alkyl methacrylate is used. In the case of a copolymer, acrylic acid esters, aromatic vinyl compounds, vinylcyan compounds, etc. are used as other monomers copolymerized with methacrylic acid esters.

(Material and forming method of cholesteric resin layer)
The cholesteric resin layer used in the present invention is a layer formed by polymerizing a cholesteric liquid crystal composition containing a polymerizable liquid crystal compound. Such a layer becomes a non-liquid crystalline resin layer cured while exhibiting the molecular orientation of the liquid crystalline compound. Note that the material referred to as a liquid crystal composition here for convenience includes not only a mixture of two or more substances but also a material made of a single substance.

Of the cholesteric resin layers used in the present invention, the second cholesteric resin layer preferably has a wide selective reflection performance. Therefore, it is preferable that the reflection band is widened in some form.
On the other hand, the first cholesteric resin layer can be preferably used even if it has a relatively narrow reflection band. Therefore, without applying such a broadening treatment, the cholesteric liquid crystal composition is applied to a substrate to form a single coating film. It can also be manufactured by a simple film forming process of obtaining and curing. However, it is possible to increase the bandwidth as necessary.

  Examples of the broadband cholesteric resin layer include (i) a cholesteric resin layer in which the spiral pitch of the chiral structure is changed stepwise, and (ii) a spiral pitch of the chiral structure continuously. Examples thereof include a changed cholesteric resin layer.

  (I) The cholesteric resin layer in which the helical pitch of the chiral structure is changed stepwise includes, for example, a cholesteric resin layer having a helical pitch that exhibits a circularly polarized light separating function with light in the blue wavelength range, and light in the green wavelength range. And a cholesteric resin layer having a helical pitch that exhibits a circularly polarized light separating function and a cholesteric resin layer having a helical pitch that exhibits a circularly polarized light separating function with light in the red wavelength region. Further, cholesteric resin layers having a central wavelength of reflected circularly polarized light of 470 nm, 550 nm, 640 nm, and 770 nm are respectively produced, and these cholesteric resin layers are arbitrarily selected, and the order of the central wavelengths of reflected light is 3 to 3 It can be obtained by laminating seven layers. When the cholesteric resin layers having different helical pitches are laminated, it is preferable that the rotation directions of the circularly polarized light reflected by the cholesteric resin layers are the same. Further, in order to obtain a liquid crystal display device having a wide viewing angle, the stacking order of the cholesteric resin layers having different spiral pitch sizes is preferably the ascending order or descending order of the spiral pitch of the chiral structure. . The lamination of these cholesteric resin layers may be merely overlaid, or may be fixed via an adhesive or an adhesive.

  (Ii) The cholesteric resin layer in which the size of the helical pitch of the chiral structure is continuously changed is not particularly limited by the manufacturing method, but as a preferable example of the manufacturing method of such a cholesteric resin layer, a cholesteric resin layer is formed. A cholesteric liquid crystal composition containing a polymerizable liquid crystalline compound for coating is preferably applied on another layer such as an alignment film to obtain a liquid crystal layer, and then one or more times of light irradiation and / or heating treatment A method of curing the liquid crystal layer can be mentioned.

  In the present invention, the cholesteric liquid crystal composition for forming the first cholesteric resin layer and the second cholesteric resin layer can contain an optional component as necessary. Other optional components include chiral agents, surfactants, polymerization initiators, solvents, polymerization inhibitors for improving pot life, antioxidants for improving durability, UV absorbers, light stabilizers, etc. Can be mentioned. These optional components can be added as long as the desired optical performance is not deteriorated.

  The method for producing the cholesteric liquid crystal composition in the present invention is not particularly limited, and can be produced by mixing the above-described components.

The method for forming the cholesteric resin layer will be further described in detail.
By applying the cholesteric liquid crystal composition directly or via an alignment film on the base material layer to obtain a coating film, and then curing the coating film by one or more times of light irradiation and / or heating treatment A cholesteric resin layer can be obtained.

More specifically, a cholesteric resin layer can be provided in the apparatus of the present invention by the following methods (M1) to (M3).
(M1) As the base material layer, a layer which is another component of the device of the present invention, such as the first or second 1 / 4λ plate, can be used, and a cholesteric resin layer can be directly provided thereon. For example, a laminated structure of the first 1 / 4λ plate and the first cholesteric resin layer can be obtained by using the first 1 / 4λ plate as a base material layer and forming a cholesteric resin layer thereon.
(M2) As the base material layer, a base material layer such as a light-transmitting resin that does not impair the effects of the present invention even if present in a laminated structure, a cholesteric resin layer is formed thereon, and Each layer may be adhered to another layer via an adhesive layer or the like and provided in the apparatus of the present invention.
(M3) An arbitrary base material may be used as the base material layer, a cholesteric resin layer may be formed thereon, transferred to another layer, and the base material layer may be peeled off and provided in the apparatus of the present invention.

  As the substrate used in the methods (M2) and (M3), a transparent resin substrate can be preferably used. The transparent resin substrate is not particularly limited, and a substrate having a thickness of 1 mm and a total light transmittance of 80% or more can be used. Specifically, alicyclic olefin polymers, chain olefin polymers such as polyethylene and polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, modified acrylic polymer, epoxy resin, Examples thereof include a single layer or laminated film made of a synthetic resin such as polystyrene or acrylic resin. Among these, an alicyclic olefin polymer or a chain olefin polymer is preferable, and an alicyclic olefin polymer is particularly preferable from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like.

In any of the methods (M1) to (M3), an alignment film can be provided on the base material layer as necessary. By providing the alignment film, the cholesteric liquid crystal composition applied thereon can be aligned in a desired direction. The alignment film is subjected to a corona discharge treatment, if necessary, on the surface of the substrate, and then a solution obtained by dissolving the alignment film material in water or a solvent, reverse gravure coating, direct gravure coating, die coating, It can be formed by applying and drying using a known method such as bar coating and then subjecting the dried coating film to a rubbing treatment. As the material of the alignment film, cellulose, silane coupling agent, polyimide, polyamide, polyvinyl alcohol, epoxy acrylate, silanol oligomer, polyacrylonitrile, phenol resin, polyoxazole, cyclized polyisoprene, and the like can be used. A modified polyamide is particularly preferred from the viewpoint of durability and the like. On the other hand, polyvinyl alcohol is particularly preferable from the viewpoint of easy transfer in the method (M3).
Examples of the modified polyamide include those obtained by modifying an aromatic polyamide or an aliphatic polyamide, and those obtained by modifying an aliphatic polyamide are preferred. Specifically, for example, modified to nylon-6, nylon-66, nylon-12, ternary to quaternary copolymer nylon, fatty acid polyamide, or fatty acid block copolymer (for example, polyether ester amide, polyester amide). Can be mentioned. Examples of the modification include terminal amino modification, carboxyl modification, hydroxyl modification and the like, and modification in which a part of the amide group is alkylaminated or N-alkoxyalkylated. Examples of the N-alkoxyalkylated modified polyamide include N-methoxymethylated part of the amide group of a copolymer nylon such as nylon-6, nylon-66, or nylon-12. The weight average molecular weight of the modified polyamide is preferably 5,000 to 500,000, more preferably 10,000 to 200,000.
The thickness of the alignment film may be a film thickness that provides desired alignment uniformity, and is preferably 0.001 to 5 μm, and more preferably 0.01 to 2 μm.

  When the surface of the base material layer or the alignment film is provided, the cholesteric liquid crystal composition can be applied to the surface of the alignment film after performing a treatment such as corona discharge treatment or rubbing as necessary. The application can be carried out by a known method such as an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method, or a bar coating method.

  Before the coating film obtained by the application is cured, an orientation treatment can be performed as necessary. The alignment treatment can be performed, for example, by heating the coating film at 50 to 150 ° C. for 0.5 to 10 minutes. By performing the alignment treatment, a substance capable of exhibiting a cholesteric liquid crystal phase in the coating film can be well aligned.

  The curing step can be performed by one or more times of light irradiation, heating treatment, or a combination thereof. Specifically, the heating conditions are, for example, a temperature of 40 to 200 ° C., preferably 50 to 200 ° C., more preferably 50 to 140 ° C., and a time of 1 second to 3 minutes, preferably 5 to 120 seconds. it can. The light used for light irradiation in the present invention includes not only visible light but also ultraviolet rays and other electromagnetic waves. Specifically, the light irradiation can be performed by, for example, irradiating light having a wavelength of 200 to 500 nm for 0.01 second to 3 minutes.

In addition, as the processing for widening the band described above, for example, a weakly irradiated ultraviolet ray of 0.01 to 50 mJ / cm ² and heating are alternately repeated a plurality of times to obtain a circularly polarized light separating sheet having a wide reflection band. You can also. After extending the reflection band by the above-mentioned weak ultraviolet irradiation, etc., a relatively strong ultraviolet ray of 50 to 10,000 mJ / cm ² is irradiated to completely polymerize the liquid crystalline compound to form a cholesteric resin layer. it can. The expansion of the reflection band and the irradiation with strong ultraviolet rays may be performed in the air, or a part or all of the process may be performed in an atmosphere in which the oxygen concentration is controlled (for example, in a nitrogen atmosphere). .

  In the present invention, the step of applying and curing the cholesteric liquid crystal composition on another layer such as an alignment film is not limited to one time, and the coating and curing are repeated a plurality of times to form two or more cholesteric resin layers. You can also. However, in the present invention, even when the cholesteric liquid crystal composition is applied and cured only once, a cholesteric resin layer having a well-oriented rod-like liquid crystalline compound having a Δn of 0.18 or more and a thickness of 5 μm or more can be easily formed. Can be formed.

  The optical element and the liquid crystal display device of the present invention include not only those specifically described above, but also those belonging to the scope of the claims of the present application and their equivalents.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example. In the following, “parts” and “%” relating to the quantity ratio of the components represent parts by weight unless otherwise specified.

<Production Example 1: Creation of Polarizer>
A 75 μm-thick polyvinyl alcohol film was uniaxially stretched 2.5 times, immersed in an aqueous solution at 30 ° C. containing 0.2 g / L of iodine and 60 g / L of potassium iodide, and then 70 g / L of boric acid and It was immersed in an aqueous solution containing 30 g / L of potassium iodide and simultaneously uniaxially stretched 6.0 times and held for 5 minutes. Finally, it was dried at room temperature for 24 hours to obtain a polarizer having an average thickness of 30 μm and a polarization degree of 99.95%.

<Production Example 2: Preparation of substrate-polarizer laminate>
A layer configuration in which a glass substrate-polarizer is bonded via an adhesive layer by applying a polyvinyl alcohol-based adhesive on one side of the polarizer obtained in Production Example 1 and bonding a glass substrate to the surface. A laminate having was prepared.

<Production Example 3: Preparation of substrate-polarizer-protective film laminate>
A polyvinyl alcohol adhesive is applied to both sides of the polarizer obtained in Production Example 1, a cellulose triacetate protective film (manufactured by Fuji Photo Film Co., Ltd .; TF80UL) is bonded to one side, and a glass substrate is bonded to the other side. Then, a laminate having a layer configuration in which the glass substrate-polarizer-protective film was bonded via the adhesive layer was prepared.

<Production Example 4: Preparation of 1 / 4λ plate>
A cycloolefin polymer film having a thickness of 100 μm (manufactured by Optes Co., Ltd .: ZEONOR film ZF-14) was longitudinally uniaxially stretched so that the in-plane retardation Re was 140 nm to obtain a 1 / 4λ plate.

<Production Example 5: Creation of stretched multilayer 1 / 4λ plate (phase difference compensation element)>
A monomer composition composed of 97.8% methyl methacrylate and 2.2% methyl acrylate was polymerized by a bulk polymerization method to obtain resin pellets.
Rubber particles were produced according to Example 3 of JP-B-55-27576. This rubber particle has a spherical three-layer structure, the core inner layer is a crosslinked polymer of methyl methacrylate and a small amount of allyl methacrylate, and the inner layer is composed of butyl acrylate and styrene as main components and a small amount of acrylic acid. It is a soft elastic copolymer obtained by crosslinking and copolymerizing allyl, and the outer layer is a hard polymer of methyl methacrylate and a small amount of ethyl acrylate. The average particle size of the inner layer was 0.19 μm, and the particle size including the outer layer was 0.22 μm.
70 parts of the resin pellets and 30 parts of the rubber particles were mixed and melt kneaded with a twin screw extruder to obtain a methacrylic acid ester polymer composition A (glass transition temperature 105 ° C.).
By coextruding the methacrylic ester polymer composition A (b layer) and the styrene maleic anhydride copolymer (glass transition temperature 130 ° C.) (a layer) at a temperature of 280 ° C., a b layer / a layer A multilayer film having an average thickness of 45/70/45 (μm) with a three-layer structure of / b layers was obtained. This multilayer film was tenter uniaxially stretched at a stretching temperature of 128 ° C., a stretch ratio of 1.4 times, and a stretching speed of 10 m / min, to obtain a stretched multilayer 1 / 4λ plate (phase difference compensation element). Further, both surfaces of the retardation compensation element were subjected to corona discharge treatment so that the wetting index was 56 dyne / cm.
Regarding the retardation value of the obtained retardation compensation element at a wavelength of 550 nm, the retardation Rth in the thickness direction was −118 nm, and the retardation Re in the in-plane direction was 140 nm.

<Production Example 6: Creation of second cholesteric resin layer>
One side of a sheet-like substrate (Zeonor film ZF14-100, manufactured by Optes) was subjected to corona discharge treatment so that the wetting index was 56 mN / m. An aqueous solution of 5% polyvinyl alcohol was applied to this corona discharge treated surface using a # 2 wire bar on one side of the film, and the coating film was dried to form an alignment film having a thickness of 0.1 μm. Next, the alignment film was rubbed to prepare a transparent resin substrate film having the alignment film.

Compound (1) (non-liquid crystalline compound, molecular weight 293.1) 7.28 parts, liquid crystalline compound (2) (liquid crystalline compound, Δn 0.18, molecular weight 846.9) 29.13 parts, chiral agent LC756 (BASF) 2.35 parts), photopolymerization initiator Irgacure 907 (manufactured by Ciba Specialty Chemicals) 1.20 parts, surfactant KH40 (manufactured by Seimi Chemical) 0.04 parts, and 2-butanone (solvent) 60.00 Parts were mixed to prepare a cholesteric liquid crystal composition. This cholesteric liquid crystal composition was applied to the surface having the alignment film of the transparent resin substrate having the alignment film prepared above at # 10 bar. The coating film is subjected to an orientation treatment at 100 ° C. for 5 minutes, and the coating film is subjected to a process of irradiation with weak ultraviolet rays of 0.1 to 45 mJ / cm ² followed by a heating treatment at 100 ° C. for 1 minute. After repeating twice, an ultraviolet ray of 800 mJ / cm ² was irradiated in a nitrogen atmosphere to form a cholesteric resin layer having a dry film thickness of 5 μm, and a laminate having a layer configuration of base material-alignment film-cholesteric resin layer Obtained.

<Example 1: Polarizer + 1 / 4λ plate + cholesteric resin layer>
One side of the ¼λ plate obtained in Production Example 4 was subjected to corona discharge treatment so that the wetting index was 56 mN / m. An aqueous solution of 5% polyvinyl alcohol was applied to this corona discharge treated surface using a # 2 wire bar on one side of the film, and the coating film was dried to form an alignment film having a thickness of 0.1 μm. Next, the alignment film was rubbed to prepare a transparent resin substrate film having the alignment film.

Liquid crystalline compound LC242 (manufactured by BASF) 96.58 parts, chiral agent LC756 (manufactured by BASF) 3.42 parts, photopolymerization initiator Irgacure 907 (manufactured by Ciba Specialty Chemicals) 3.10 parts, surfactant KH40 ( A cholesteric liquid crystal composition was prepared by mixing 0.22 part of Seimi Chemical Co., Ltd. and 241.08 part of 2-butanone (solvent). This cholesteric liquid crystal composition was applied to the surface having the alignment film of the transparent resin substrate having the alignment film prepared above. The coating film is subjected to orientation treatment at 100 ° C. for 5 minutes, the coating film is irradiated with 500 mJ / cm ² ultraviolet rays to form a cholesteric resin layer having a dry film thickness of 2 μm, and a quarter λ plate-cholesteric resin layer layer The laminated body (1) which has a structure was obtained. The center of the selective reflection band of front incident light of this cholesteric resin layer is 745 nm, and its half-value width is 110 nm.
On the polarizer of the laminate obtained in Production Example 2, this laminate (1) was pasted via an adhesive layer (Nitto Denko's transparent double-sided adhesive tape, the same applies hereinafter), and a glass substrate-first polarizer. -The optical element (1) which has the layer structure of the 1st quarter-lambda board-the 1st cholesteric resin layer was obtained. The optical element (1) is rectangular, the angle formed by the long side direction and the absorption axis of the first polarizer is 90 °, and the optical axis of the first polarizer and the first quarter-λ plate is optical. The angle formed by the axis was 45 °.

  The optical characteristics of the obtained optical element (1) were evaluated. Polar angle and wavelength when the first cholesteric resin layer side is the entrance surface, the glass substrate side is the exit surface, light is incident in the normal direction, and the observation direction is tilted in the azimuth 45 ° and 135 ° directions The relationship with the transmittance of light at 610 nm was measured using a spectrophotometer (manufactured by JASCO: V-570). The results are shown in FIG. As is clear from the results of FIG. 7, a result with high symmetry of viewing angle characteristics was obtained.

  Furthermore, a liquid crystal cell including the glass substrate of the obtained optical element (1) as a constituent element is configured by a regular method, and a second polarizer is provided by a regular method on the surface on the display surface side. It was installed on a backlight device having a reflecting plate to obtain a liquid crystal display device schematically shown in FIG. The obtained liquid crystal display device was installed and driven so that the long side of the display surface was in the horizontal direction and the short side was in the vertical direction, and when the display surface was observed, the screen turned red as the polar angle of the observation angle increased. There was little, and there was little difference of the right and left of the degree of reddening, and it was close to symmetry.

<Example 2: Polarizer + 1 / 4λ plate + cholesteric resin layer + 1 / 4λ plate>
The optical element (1) obtained in Example 1 was attached to the surface on the first cholesteric resin layer side with another 1 / 4λ plate obtained in Production Example 4 through an adhesive layer, and a glass substrate— An optical element (2) having a layer configuration of a first polarizer, a first 1 / 4λ plate, a first cholesteric resin layer, and a second 1 / 4λ plate was obtained. The angle formed by the slow axis of the first 1 / 4λ plate and the slow axis of the second 1 / 4λ plate was 90 °.

  The optical characteristics of the obtained optical element (2) were evaluated in the same manner as in Example 1. The results are shown in FIG. As is clear from the results of FIG. 8, a high symmetry of viewing angle characteristics was obtained.

  Further, a liquid crystal cell including the glass substrate of the obtained optical element (2) as a constituent element is configured by a regular method, and a second polarizer is provided by a regular method on the surface on the display surface side. The liquid crystal display device shown in FIG. 5 was obtained by installing on a backlight device having a reflector. The obtained liquid crystal display device was installed and driven so that the long side of the display surface was in the horizontal direction and the short side was in the vertical direction, and when the display surface was observed, the screen turned red as the polar angle of the observation angle increased. There was little, and there was little difference of the right and left of the degree of reddening, and it was close to symmetry.

<Comparative Example 1: Polarizer + Cholesteric Resin Layer Laminate>
One side of a sheet-like substrate (Zeonor film ZF14-100, manufactured by Optes) was subjected to corona discharge treatment so that the wetting index was 56 mN / m. An aqueous solution of 5% polyvinyl alcohol was applied to this corona discharge treated surface using a # 2 wire bar on one side of the film, and the coating film was dried to form an alignment film having a thickness of 0.1 μm. Next, the alignment film was rubbed to prepare a transparent resin substrate film having the alignment film.

Liquid crystalline compound LC242 (manufactured by BASF) 96.58 parts, chiral agent LC756 (manufactured by BASF) 3.42 parts, photopolymerization initiator Irgacure 907 (manufactured by Ciba Specialty Chemicals) 3.10 parts, surfactant KH40 ( A cholesteric liquid crystal composition was prepared by mixing 0.22 part of Seimi Chemical Co., Ltd. and 241.08 part of 2-butanone (solvent). This cholesteric liquid crystal composition was applied to the surface having the alignment film of the transparent resin substrate having the alignment film prepared above. The coating film is subjected to orientation treatment at 100 ° C. for 5 minutes, and the coating film is irradiated with 500 mJ / cm ² ultraviolet rays to form a cholesteric resin layer having a dry film thickness of 2 μm. A laminate (2) having was obtained.
On the polarizer of the laminate obtained in Production Example 2, the surface of the laminate (2) on the sheet-like substrate side is pasted via an adhesive layer, and a glass substrate-first polarizer-sheet-like substrate is attached. An optical element (C1) having a layer configuration of material-first cholesteric resin layer was obtained. The optical element (C1) was rectangular.

  The optical characteristics of the obtained optical element (C1) were evaluated in the same manner as in Example 1. The results are shown in FIG. As is clear from the results in FIG. 9, the symmetry of the viewing angle characteristic was inferior to that of Example 1.

  Further, a liquid crystal cell including the glass substrate of the obtained optical element (C1) as a constituent element is configured by a standard method, and a second polarizer is provided by a standard method on the surface on the display surface side. The liquid crystal display device was obtained by installing on a backlight device having a reflector. The obtained liquid crystal display device was installed and driven so that the long side of the display surface was in the horizontal direction and the short side was in the vertical direction, and when the display surface was observed, the screen turned red as the polar angle of the observation angle increased. The difference between the left and right degrees was greater than in Example 1, and the symmetry was poor.

<Example 3: Polarizer + Protective film + 1 / 4λ plate + Cholesteric resin layer>
One side of the ¼λ plate obtained in Production Example 4 was subjected to corona discharge treatment so that the wetting index was 56 mN / m. An aqueous solution of 5% polyvinyl alcohol was applied to this corona discharge treated surface using a # 2 wire bar on one side of the film, and the coating film was dried to form an alignment film having a thickness of 0.1 μm. Next, the alignment film was rubbed to prepare a transparent resin substrate film having the alignment film.

Liquid crystalline compound LC242 (manufactured by BASF) 96.58 parts, chiral agent LC756 (manufactured by BASF) 3.42 parts, photopolymerization initiator Irgacure 907 (manufactured by Ciba Specialty Chemicals) 3.10 parts, surfactant KH40 ( A cholesteric liquid crystal composition was prepared by mixing 0.22 part of Seimi Chemical Co., Ltd. and 241.08 part of 2-butanone (solvent). This cholesteric liquid crystal composition was applied to the surface having the alignment film of the transparent resin substrate having the alignment film prepared above. The coating film is subjected to orientation treatment at 100 ° C. for 5 minutes, the coating film is irradiated with 500 mJ / cm ² ultraviolet rays to form a cholesteric resin layer having a dry film thickness of 2 μm, and a quarter λ plate-cholesteric resin layer layer A laminate (3) having a configuration was obtained.
This laminate (3) was pasted on the polarizer of the laminate obtained in Production Example 3 via an adhesive layer, and a glass substrate-first polarizer-protective film-first 1 / 4λ plate- An optical element (3) having the layer configuration of the first cholesteric resin layer was obtained. The optical element (3) is rectangular, the angle between the long side direction and the absorption axis of the first polarizer is 90 °, and the absorption axis of the first polarizer and the first 1 / 4λ plate The angle formed by the optical axis was 45 °.

  The optical characteristics of the obtained optical element (3) were evaluated in the same manner as in Example 1. The results are shown in FIG. As is clear from the results of FIG. 10, a result with high symmetry of viewing angle characteristics was obtained.

  Further, a liquid crystal cell including the glass substrate of the obtained optical element (3) as a constituent element is configured by a regular method, and a second polarizer is provided by a regular method on the surface on the display surface side. The liquid crystal display device was obtained by installing on a backlight device having a reflector. The obtained liquid crystal display device was installed and driven so that the long side of the display surface was in the horizontal direction and the short side was in the vertical direction, and when the display surface was observed, the screen turned red as the polar angle of the observation angle increased. There was little, and there was little difference of the right and left of the degree of reddening, and it was close to symmetry.

<Example 4: Polarizer + protective film + 1 / 4λ plate + cholesteric resin layer + 1 / 4λ plate>
One more quarter λ plate obtained in Production Example 4 was attached to the surface of the optical element (3) obtained in Example 3 on the first cholesteric resin layer side through an adhesive layer. An optical element (4) having a layer configuration of a first polarizer, a protective film, a first 1 / 4λ plate, a first cholesteric resin layer, and a second 1 / 4λ plate was obtained. The angle formed by the slow axis of the first 1 / 4λ plate and the slow axis of the second 1 / 4λ plate was 90 °.

  The optical characteristics of the obtained optical element (4) were evaluated in the same manner as in Example 1. The results are shown in FIG. As is clear from the results of FIG. 11, a high symmetry of viewing angle characteristics was obtained.

  Furthermore, a liquid crystal cell including the glass substrate of the obtained optical element (4) as a constituent element is configured by a regular method, and a second polarizer is provided by a regular method on the surface on the display surface side. The liquid crystal display device was obtained by installing on a backlight device having a reflector. The obtained liquid crystal display device was installed and driven so that the long side of the display surface was in the horizontal direction and the short side was in the vertical direction, and when the display surface was observed, the screen turned red as the polar angle of the observation angle increased. There was little, and there was little difference of the right and left of the degree of reddening, and it was close to symmetry.

<Comparative Example 2: Polarizer + Protective Film + Cholesteric Resin Layer Laminate>
One side of a sheet-like substrate (Zeonor film ZF14-100, manufactured by Optes) was subjected to corona discharge treatment so that the wetting index was 56 mN / m. An aqueous solution of 5% polyvinyl alcohol was applied to this corona discharge treated surface using a # 2 wire bar on one side of the film, and the coating film was dried to form an alignment film having a thickness of 0.1 μm. Next, the alignment film was rubbed to prepare a transparent resin substrate film having the alignment film.

Liquid crystalline compound LC242 (manufactured by BASF) 96.58 parts, chiral agent LC756 (manufactured by BASF) 3.42 parts, photopolymerization initiator Irgacure 907 (manufactured by Ciba Specialty Chemicals) 3.10 parts, surfactant KH40 ( A cholesteric liquid crystal composition was prepared by mixing 0.22 part of Seimi Chemical Co., Ltd. and 241.08 part of 2-butanone (solvent). This cholesteric liquid crystal composition was applied to the surface having the alignment film of the transparent resin substrate having the alignment film prepared above. The coating film is subjected to orientation treatment at 100 ° C. for 5 minutes, and the coating film is irradiated with 500 mJ / cm ² ultraviolet rays to form a cholesteric resin layer having a dry film thickness of 2 μm. A laminate (4) having was obtained.
This laminate (4) is stuck on the polarizer of the laminate obtained in Production Example 3 via an adhesive layer, and the glass substrate-first polarizer-protective film-sheet-like substrate-first. An optical element (C2) having a layer configuration of a cholesteric resin layer was obtained. The optical element (C2) was rectangular.

  The optical characteristics of the obtained optical element (C2) were evaluated in the same manner as in Example 1. The results are shown in FIG. As is clear from the results of FIG. 12, the symmetry of the viewing angle characteristic was inferior to that of Example 3.

  Further, a liquid crystal cell including the glass substrate of the obtained optical element (C2) as a constituent element is configured by a standard method, and a second polarizer is provided by a standard method on a surface on the display surface side. The liquid crystal display device was obtained by installing on a backlight device having a reflector. The obtained liquid crystal display device was installed and driven so that the long side of the display surface was in the horizontal direction and the short side was in the vertical direction, and when the display surface was observed, the screen turned red as the polar angle of the observation angle increased. The difference between the left and right degrees was greater than in Example 3, and the symmetry was poor.

<Example 5: Polarizer + 1 / 4λ plate + cholesteric resin layer + cholesteric resin layer>
One side of a sheet-like substrate (Zeonor film ZF14-100, manufactured by Optes) was subjected to corona discharge treatment so that the wetting index was 56 mN / m. An aqueous solution of 5% polyvinyl alcohol was applied to this corona discharge treated surface using a # 2 wire bar on one side of the film, and the coating film was dried to form an alignment film having a thickness of 0.1 μm. Next, the alignment film was rubbed to prepare a transparent resin substrate film having the alignment film.

Liquid crystalline compound LC242 (manufactured by BASF) 96.58 parts, photopolymerization initiator Irgacure 907 (manufactured by Ciba Specialty Chemicals) 3.10 parts, surfactant KH40 (manufactured by Seimi Chemical) 0.22 parts, chiral agent LC756 A chiral agent that forms a helical structure with a reverse rotation was added, and 409.84 parts of 2-butanone (solvent) was mixed to prepare a cholesteric liquid crystal composition. This cholesteric liquid crystal composition was applied to the surface having the alignment film of the transparent resin substrate having the alignment film prepared above. The coating film is subjected to orientation treatment at 100 ° C. for 5 minutes, the coating film is irradiated with 500 mJ / cm ² ultraviolet rays to form a cholesteric resin layer having a dry film thickness of 2 μm, and a quarter λ plate-cholesteric resin layer layer A laminate (5) having a configuration was obtained. The center of the selective reflection band of front incident light of this cholesteric resin layer is 715 nm, and its half-value width is 130 nm.
On the polarizer of the laminate obtained in Production Example 2, the stretched multilayer 1 / 4λ film obtained in Production Example 5, the second cholesteric resin layer obtained in Production Example 6, and the laminate (5) are stacked in this order. And an optical element (5) having a layer configuration of glass substrate-first polarizer-first ¼λ plate-second cholesteric resin layer-first cholesteric resin layer was obtained.

  The optical characteristics of the obtained optical element (5) were evaluated in the same manner as in Example 1. High symmetry of viewing angle characteristics was obtained.

It is a disassembled perspective view which shows roughly an example of the liquid crystal display device of this invention containing the optical element of this invention. It is sectional drawing which shows schematically the aspect of the cholesteric resin layer in the optical element of this invention. It is a perspective view which shows the relationship between the display surface of a display apparatus, an azimuth angle, and a polar angle in this invention. It is an elevational view showing the relationship between the display surface of the display device and the azimuth angle in the present invention. It is a disassembled perspective view which shows schematically another example of the liquid crystal display device of this invention containing the optical element of this invention. It is a disassembled perspective view which shows roughly another example of the liquid crystal display device of this invention containing the optical element of this invention. 6 is a graph showing measurement results of characteristics of the optical element in Example 1. 6 is a graph showing measurement results of characteristics of an optical element in Example 2. 6 is a graph showing measurement results of characteristics of an optical element in Comparative Example 1. 10 is a graph showing measurement results of characteristics of an optical element in Example 3. 10 is a graph showing measurement results of characteristics of an optical element in Example 4. 10 is a graph showing measurement results of characteristics of an optical element in Comparative Example 2.

Explanation of symbols

3 Cholesteric Resin Layer 11 First Polarizer 12 Liquid Crystal Cell 13 Second Polarizer 17 First 1 / 4λ Plate 18 First Cholesteric Resin Layer 19 Light Source 20 Reflector 21 Second 1 / 4λ Plate 22 Second Cholesteric resin layer 310 display surface

Claims (10)

  An optical element having at least a first polarizer, a first ¼λ plate, and a resin layer having a first cholesteric regularity in this order, and a front surface of the resin layer having the first cholesteric regularity An optical element characterized in that the center of the selective reflection band of incident light is 495 nm or less or 620 nm or more. The optical element according to claim 1,
A second quarter λ plate is further provided outside the resin layer having the first cholesteric regularity, and the slow axis of the second quarter λ plate is the slow axis of the first quarter λ plate. The optical element according to claim 1, wherein the optical element is in a direction perpendicular to the phase axis. The optical element according to claim 1 or 2,
The optical element, wherein the first polarizer, the first ¼λ plate, and the resin layer having the first cholesteric regularity are integrated. The optical element according to any one of claims 1 to 3,
A resin layer having a second cholesteric regularity between the first ¼λ plate and the resin layer having the first cholesteric regularity or outside the resin layer having the first cholesteric regularity. The resin layer having the second cholesteric regularity has a selective reflection performance in a region of at least 480 to 620 nm with respect to the front incident light, and the resin layer having the first cholesteric regularity and the second The optical element according to claim 1, wherein the twist direction of molecules of the resin layer having the cholesteric regularity is reverse. The optical element according to any one of claims 1 to 4,
The optical element, wherein an absorption axis of the first polarizer and an optical axis of the first ¼λ plate form an angle of about 45 °.   A liquid crystal display device comprising at least a second polarizer, a liquid crystal cell, a first polarizer, a first ¼λ plate, a resin layer having a first cholesteric regularity, and a light source in this order, A liquid crystal display device, wherein the center of the selective reflection band of front incident light of a resin layer having one cholesteric regularity is 495 nm or less or 620 nm or more. The liquid crystal display device according to claim 6.
A second ¼λ plate is further provided between the resin layer having the first cholesteric regularity and the light source, and the slow axis of the second ¼λ plate is the first 1 / λ. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is in a direction perpendicular to the slow axis of the 4λ plate. The liquid crystal display device according to claim 6 or 7,
The liquid crystal display device, wherein the first polarizer, the first ¼λ plate, and the resin layer having the first cholesteric regularity are integrated. The liquid crystal display device according to any one of claims 6 to 8,
A second cholesteric regularity is provided between the first ¼λ plate and the resin layer having the first cholesteric regularity or between the resin layer having the first cholesteric regularity and the light source. The resin layer having the second cholesteric regularity has a selective reflection performance in a region of at least 480 to 620 nm with respect to the front incident light, and the resin layer having the first cholesteric regularity. The liquid crystal display device according to claim 1, wherein the twist direction of molecules of the resin layer having the second cholesteric regularity is reverse. The liquid crystal display device according to any one of claims 6 to 9,
The liquid crystal display device, wherein an absorption axis of the first polarizer and an optical axis of the first ¼λ plate form an angle of about 45 °.

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