JP2007322778A - Elliptically polarizing plate, method of manufacturing elliptically polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elliptically polarizing plate which does not cause malfunction such as delamination even under conditions of high temperature and high humidity by simplifying a layer structure of the elliptically polarizing plate. <P>SOLUTION: The elliptically polarizing plate comprises: a transmissive protection film; a polarizing element; and an optically anisotropic element, stacked in this order, wherein the optically anisotropic element includes a hybrid-nematic alignment liquid crystal layer in which a liquid crystalline composition at least exhibiting an optically positive uniaxiality is subjected to hybrid-nematic alignment in the liquid crystalline state and thereafter the alignment is fixed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an elliptically polarizing plate comprising a hybrid nematic alignment liquid crystal layer in which a hybrid nematic alignment structure is fixed, and a method for producing the same. Furthermore, the present invention relates to a liquid crystal display device using the elliptically polarizing plate.

There are three types of liquid crystal display devices: a transmissive type capable of displaying an image in a transmissive mode, a reflective type capable of displaying an image in a reflective mode, and a transflective type capable of displaying an image in both a transmissive mode and a reflective mode. Due to its thin and light features, it is widely used as a display device for notebook computers and televisions. In particular, the transflective liquid crystal display device employs a display method that combines a reflective type and a transmissive type. By switching to one of the display methods according to the ambient brightness, the power consumption is reduced, and However, since clear display can be performed even in a dark place, it is frequently used in various portable electronic devices.
By the way, the transmissive, reflective, and transflective liquid crystal display devices, particularly in the transmissive mode, have a lower display contrast and a different display color when viewed obliquely due to the refractive index anisotropy of the liquid crystal molecules. Or the problem of viewing angle such as inversion of gradation cannot be avoided, and improvement thereof is desired.
As a method for solving this problem, in a conventional transmissive liquid crystal display device using a TN mode (a twist angle of liquid crystal of 90 degrees), an optical compensation film has been proposed and put into practical use between a liquid crystal cell and an upper and lower polarizing plate. ing.

For example, a configuration in which an optical compensation film in which a discotic liquid crystal is hybrid-aligned is disposed between the liquid crystal cell and the upper and lower polarizing plates, and an optical compensation film in which a liquid crystalline polymer is hybrid-nematically aligned is disposed between the liquid crystal cell and the upper and lower polarizing plates. (Patent Documents 1 to 3).
In the transflective liquid crystal display device, in the transmission mode, it is necessary to dispose circularly polarizing plates composed of one or a plurality of uniaxial retardation films and polarizing plates above and below the liquid crystal cell in terms of display principle. is there.
In order to increase the viewing angle of the transmission mode of the transflective liquid crystal display device, a method using an optical compensation film in which a nematic hybrid alignment is performed on a circularly polarizing plate disposed between a liquid crystal cell and a backlight has been proposed (patent) Reference 4).
On the other hand, there is a growing demand for thinner and lighter devices, as represented by mobile phones and portable information terminal devices, which have been widely spread in recent years, while increasing the optical properties. Along with this, reduction in thickness and weight of optical films used in display devices is also desired. For this reason, attempts have been made to make polymer stretched films thinner, but there are limits to making polymer stretched films thinner due to restrictions in optical properties and manufacturing processes. There was a problem that the thickness was increased.

In order to solve such a problem, it is considered effective to use an optical element made of a liquid crystal material without using a support substrate film as in Patent Document 5, but in order to apply the optical element to a liquid crystal display device, Furthermore, it is necessary to stick together with a polarizing plate and an adhesive.
When laminating the optical elements, there is anxiety in handling properties, durability, etc. when there is no support substrate film. On the other hand, if the optical element can be laminated directly on one supporting substrate film having a polarizing element, the film can be made thinner by omitting the adhesive / adhesive layer, and a film excellent in durability and the like can be obtained. Although it can be achieved, an industrial manufacturing method for laminating the optical elements has not been established.
Japanese Patent No. 2640083 JP-A-11-194325 Japanese Patent Laid-Open No. 11-194371 JP 2002-31717 A JP-A-8-278491

  An object of the present invention is to realize both high performance, high durability, and significant thinning of optical characteristics, which has been difficult only with a stretched polymer film. That is, paying attention to an optical film using a liquid crystal compound that is thinner and can exhibit an excellent optical function, an elliptically polarizing plate in which an optical anisotropic element is laminated on one supporting substrate film having a polarizing element, and a method for producing the same It is providing the liquid crystal display device which has arrange | positioned the said elliptically polarizing plate.

That is, the first of the present invention is an elliptically polarizing plate in which a light-transmitting protective film, a polarizing element and an optical anisotropic element are laminated in this order, and the optical anisotropic element exhibits at least positive uniaxiality. The present invention relates to an elliptically polarizing plate comprising a hybrid nematic alignment liquid crystal layer in which a liquid crystal composition is hybrid nematically aligned in a liquid crystal state and then the alignment is fixed.
A second aspect of the present invention relates to the elliptically polarizing plate according to the first aspect of the present invention, wherein the translucent protective film, the polarizing element and the optical anisotropic element are in the form of a long film.
According to a third aspect of the present invention, the optically anisotropic element is composed of at least a hybrid nematic alignment liquid crystal layer, the liquid crystal layer has an average tilt angle of 5 ° to 45 °, and has a refractive index anisotropy Δn at a wavelength of 550 nm and optical properties. The elliptically polarizing plate according to the first or second aspect of the present invention, wherein the product (Δn · d) with the thickness d of the anisotropic body is in the range of 30 nm to 200 nm.
4th of this invention is related with the elliptically polarizing plate in any one of 1-3 of this invention, wherein a translucent protective film is a triacetyl cellulose.
A fifth aspect of the present invention relates to the elliptically polarizing plate according to any one of the first to third aspects of the present invention, wherein the translucent protective film is a cycloolefin polymer.
6th of this invention is related with the elliptically polarizing plate in any one of 1st-5th of this invention characterized by the thickness of an elliptically polarizing plate being 150 micrometers or less.

A seventh aspect of the present invention is that any one of the first to sixth aspects of the present invention is characterized in that an alignment film in which the liquid crystalline composition forms a nematic alignment is provided between the polarizing element and the optical anisotropic element. It relates to the elliptically polarizing plate.
An eighth aspect of the present invention is the optically anisotropic element according to any one of the first to seventh aspects of the present invention, wherein a translucent overcoat layer is provided on the surface opposite to the polarizing element. The present invention relates to an elliptically polarizing plate.
A ninth aspect of the present invention relates to the elliptically polarizing plate according to the eighth aspect of the present invention, wherein the translucent overcoat layer is made of an acrylic resin.
The tenth aspect of the present invention relates to an elliptically polarizing plate, wherein at least one optical film is further laminated on the elliptically polarizing plate according to any one of the first to ninth aspects of the present invention.
The eleventh aspect of the present invention relates to the elliptically polarizing plate according to the tenth aspect of the present invention, wherein the optical film is a polymer stretched film.
A twelfth aspect of the present invention relates to the elliptically polarizing plate according to the tenth aspect of the present invention, wherein the optical film is a liquid crystalline film.

According to the thirteenth aspect of the present invention, (1) a laminate (A) comprising a translucent protective film / adhesive layer 1 / polarizing element, wherein the translucent protective film is adhered to the polarizing element via the adhesive layer 1. (2) A layer of a liquid crystalline composition exhibiting at least positive uniaxiality is formed on a rubbing-treated alignment substrate, the layer is hybrid nematically aligned, and the alignment is fixed Forming the optically anisotropic element to obtain a laminate (B) composed of an alignment substrate / optically anisotropic element, and (3) the optically anisotropic element side of the laminate (B) with an adhesive layer. 2 is bonded to the polarizing element side of the laminate (A) through 2, and then the alignment substrate is peeled off to transfer the optical anisotropic element to the laminate (A). A third step of obtaining an elliptically polarizing plate comprising layer 1 / polarizing element / adhesive layer 2 / optically anisotropic element;
The manufacturing method of the elliptically-polarizing plate characterized by passing through each process of these.

  According to the fourteenth aspect of the present invention, (1) a laminate comprising a translucent protective film / adhesive layer 1 / a polarizing element (A), wherein the translucent protective film is adhered to the polarizing element via the adhesive layer 1. (2) A rubbing treatment is performed on the polarizing element of the laminate (A) to form a layer of a liquid crystalline composition exhibiting at least positive uniaxiality, and the layer is hybrid nematically aligned. Thereafter, at least each step of the second step of fixing the orientation to form an optically anisotropic element and obtaining an elliptically polarizing plate comprising a translucent protective film / adhesive layer 1 / polarizing element / optically anisotropic element The present invention relates to a method for manufacturing an elliptically polarizing plate.

A fifteenth aspect of the present invention is characterized in that, in the fourteenth aspect of the present invention, a rubbing treatment is performed after providing an alignment film on which at least a positive uniaxial liquid crystalline composition forms a nematic alignment on a polarizing element. The present invention relates to a method for producing an elliptically polarizing plate according to the fourteenth aspect of the present invention.
A sixteenth aspect of the present invention relates to the method for producing an elliptically polarizing plate according to the thirteenth or fourteenth aspect of the present invention, wherein the translucent protective film is triacetyl cellulose or a cycloolefin polymer.
17th of this invention is related with the manufacturing method of the elliptically polarizing plate as described in 13 or 14 of this invention characterized by the surface treatment of the translucent protective film.
The eighteenth aspect of the present invention relates to the method for producing an elliptically polarizing plate according to the seventeenth aspect of the present invention, wherein the surface treatment is a saponification treatment.

A nineteenth aspect of the present invention relates to the method for manufacturing an elliptically polarizing plate according to the seventeenth aspect of the present invention, wherein the surface treatment is a corona discharge treatment.
A twentieth aspect of the present invention relates to the method for manufacturing an elliptically polarizing plate according to the thirteenth or fourteenth aspect of the present invention, wherein the polarizing element is surface-treated.
A twenty-first aspect of the present invention relates to the method for manufacturing an elliptically polarizing plate according to the twentieth aspect of the present invention, wherein the surface treatment is a corona discharge treatment.
A twenty-second aspect of the present invention relates to a liquid crystal display device in which the elliptically polarizing plate according to any one of the first to twelfth aspects of the present invention is disposed on at least one surface of a liquid crystal cell.

  The elliptically polarizing plate of the present invention is less susceptible to damage to the polymer liquid crystal layer in the step of bonding the optically anisotropic element and the polarizing element, and is excellent in adhesiveness of the optically anisotropic element. Furthermore, since the number of laminate layers constituting the elliptically polarizing plate is small, there is no peeling or generation of bubbles at the interface in the accelerated durability test. Also in the bonding step with the polarizing element, since it can be bonded in the form of a long film, there is an advantage that the bonding step can be rationalized from the conventional method.

Hereinafter, the present invention will be described in detail.
In the present invention, an elliptically polarizing plate is produced by adhering an optically anisotropic element to a polarizing element directly or via an adhesive. By doing so, the number of layers can be reduced as compared with a conventional elliptical polarizing plate in which an optical anisotropic element is bonded to a polarizing plate in which both sides of the polarizing element are protected with an optical film such as a triacetyl cellulose film. As a result, the total thickness of the elliptically polarizing plate can be reduced, and the influence of shrinkage strain due to the difference in the expansion and contraction behavior of each layer due to heat or humidity can be reduced, eliminating problems such as peeling at the bonded interface. Is possible.

The layer structure of the elliptically polarizing plate obtained in the present invention is composed of any one of the following two structures (I) to (II), and a member such as a translucent overcoat layer is further provided as necessary. In addition to these, except that the liquid crystal composition showing positive uniaxiality in the present invention uses an optical anisotropic element composed of a hybrid nematic alignment liquid crystal layer in which a hybrid nematic alignment structure is fixed in a liquid crystal state. There are no particular restrictions. In terms of obtaining an elliptically polarizing plate having a small thickness, any of the configurations (I) to (II) may be used.
(I) Translucent protective film / adhesive layer 1 / polarizing element / adhesive layer 2 / optical anisotropic element (II) Translucent protective film / adhesive layer 1 / polarizing element / optical anisotropic element

Hereafter, the structural member used for this invention is demonstrated in order.
First, the liquid crystal composition used in the present invention will be described.
The optically anisotropic element used in the present invention has a liquid crystalline composition mainly composed of a liquid crystalline composition exhibiting optically positive uniaxiality, specifically a liquid crystalline polymer compound exhibiting optically positive uniaxiality. It is a layer comprising at least a hybrid nematic alignment liquid crystal layer composed of a polymer composition, in which a hybrid nematic alignment structure having an average tilt angle of 5 ° to 45 ° formed in the liquid crystal state is fixed.
Here, the hybrid nematic alignment referred to in the present invention means that the liquid crystal molecules are hybrid nematic alignment, and the angle formed by the director of the liquid crystal molecules and the plane of the liquid crystal layer is different between the upper surface and the lower surface of the layer. Say. Therefore, the angle formed by the director and the layer plane is different between the vicinity of the upper surface interface and the vicinity of the lower surface interface, so that the angle continuously changes between the upper surface and the lower surface of the layer. It can be said.
In the hybrid nematic alignment liquid crystal layer in which the hybrid nematic alignment state is fixed, the directors of the liquid crystal molecules are oriented at different angles at all positions in the film thickness direction of the layer. Therefore, the optical axis no longer exists when the layer is viewed as a structure called a layer.

  The average tilt angle in the present invention means the average value of the angle formed by the director of the liquid crystal molecules and the plane of the hybrid nematic alignment liquid crystal layer in the film thickness direction of the hybrid nematic alignment liquid crystal layer. In the hybrid nematic alignment liquid crystal layer used in the present invention, the angle formed by the director and the layer plane in the vicinity of one interface of the layer is usually 25 to 90 degrees as an absolute value, preferably 35 to 85 degrees, and more preferably Has an angle of 45 to 80 degrees, and on the opposite side of the plane, the absolute value is usually 0 to 20 degrees, preferably 0 to 10 degrees, and the average tilt angle is an absolute value. Is usually 5 to 45 degrees, preferably 15 to 43 degrees, and more preferably 25 to 40 degrees. When the average tilt angle is out of the above range, it is not desirable because there is a risk of a decrease in contrast when viewed from an oblique direction. The average tilt angle can be obtained by applying a crystal rotation method.

  The hybrid nematic alignment liquid crystal layer constituting the optical anisotropic element used in the present invention may be any liquid crystal compound as long as the hybrid nematic alignment state as described above is fixed and has a specific average tilt angle. It may be formed from. For example, a layer obtained by forming a low molecular liquid crystal in a hybrid nematic alignment in a liquid crystal state and then fixing by photocrosslinking or thermal crosslinking, or a liquid crystalline polymer in a hybrid nematic alignment in a liquid crystal state and then cooling the alignment A liquid crystal layer obtained by fixing can be used. The hybrid nematic alignment liquid crystal layer referred to in the present invention does not ask whether or not the liquid crystal layer itself exhibits liquid crystallinity, and is obtained by forming a liquid crystal compound such as a low molecular liquid crystal or a liquid crystal polymer into a film. Means what can be done.

  In addition, the film thickness of the liquid crystal layer for the hybrid nematic alignment liquid crystal layer to exhibit a better viewing angle improving effect on the liquid crystal display device depends on the method of the target liquid crystal display element and various optical parameters. Therefore, although it cannot be generally stated, it is usually in the range of 0.1 μm to 10 μm, preferably 0.2 μm to 5 μm, particularly preferably 0.4 μm to 4 μm. When the film thickness is less than 0.1 μm, a sufficient compensation effect may not be obtained. If the film thickness exceeds 10 μm, the display on the liquid crystal display device may be unnecessarily colored.

  The in-plane apparent retardation value when viewed from the normal direction of the hybrid nematic alignment liquid crystal layer is a direction perpendicular to the refractive index in the direction parallel to the director (hereinafter referred to as ne) in the liquid crystal layer. Are different in refractive index (hereinafter referred to as no), and when the value obtained by subtracting no from ne is the apparent birefringence (Δn = ne−no), the apparent retardation value is apparent. It is assumed that it is given by the product (Δn · d) of the birefringence and the absolute film thickness. This value can be easily obtained by polarization optical measurement such as ellipsometry. Δn · d of the hybrid nematic alignment liquid crystal layer is usually in the range of 10 nm to 400 nm, preferably 30 nm to 200 nm, particularly preferably 50 nm to 150 nm with respect to monochromatic light at a wavelength of 550 nm. When Δn · d is less than 10 nm, a sufficient viewing angle expansion effect may not be obtained. On the other hand, if it is larger than 400 nm, the liquid crystal display device may be unnecessarily colored when viewed from an oblique direction.

The specific arrangement conditions of the hybrid nematic alignment liquid crystal layer in the liquid crystal display device of the present invention will be described. In explaining the more specific arrangement conditions, the upper and lower sides of the hybrid nematic alignment liquid crystal layer are shown in FIGS. The tilt direction of the liquid crystal layer and the pretilt direction of the liquid crystal cell layer are respectively defined below.
First, the upper and lower sides of an optical anisotropic element composed of a hybrid nematic alignment liquid crystal layer are respectively defined by the angle formed between the liquid crystal molecule director in the vicinity of the hybrid nematic interface constituting the optical anisotropic element and the plane of the liquid crystal layer. The surface where the angle formed by the director and the liquid crystal layer plane forms an angle of 25 to 90 degrees on the acute angle side is defined as b-plane, and the angle forms the angle of 0 to 20 degrees on the acute angle side Is the c-plane.
When the c-plane is viewed from the b-plane of the optical anisotropic element through the liquid crystal layer, the angle formed by the liquid crystal molecule director and the projection component on the c-plane of the director is an acute angle and a direction parallel to the projection component Is defined as the tilt direction of the hybrid nematic alignment liquid crystal layer (FIGS. 1 and 2).
Next, usually, at the cell interface of the liquid crystal cell layer, the driving low-molecular liquid crystal is not parallel to the cell interface but is inclined at a certain angle, and this angle is generally referred to as a pretilt angle. A direction in which the angle formed by the projection component on the director interface is an acute angle and parallel to the projection component of the director is defined as the pretilt direction of the liquid crystal cell layer (FIG. 3).

  As the liquid crystalline polymer, various main chain type liquid crystalline polymers, side chain type liquid crystalline polymers, or a mixture thereof can be used. Main chain type liquid crystalline polymers include polyester, polyamide, polycarbonate, polyimide, polyurethane, polybenzimidazole, polybenzoxazole, polybenzthiazole, polyazomethine, polyesteramide, polyester carbonate And a polyesterimide-based liquid crystalline polymer, or a mixture thereof. Among these, semi-aromatic polyester liquid crystalline polymers in which mesogenic groups that give liquid crystallinity and bent chains such as polymethylene, polyethylene oxide, and polysiloxane are alternately bonded, or wholly aromatic polyester-based liquid crystals without bent chains. A functional polymer is desirable in the present invention. Further, as the side chain type liquid crystalline polymer, a polymer having a skeleton chain having a linear or cyclic structure such as polyacrylate, polymethacrylate, polyvinyl, polysiloxane, polyether, and polymalonate is used. And a liquid crystalline polymer having a mesogenic group bonded thereto, or a mixture thereof. Among these, a side chain type liquid crystalline polymer in which a mesogenic group that gives liquid crystallinity is bonded to a skeleton chain through a spacer made of a bent chain, and a liquid crystal structure having a molecular structure having a mesogen in both the main chain and the side chain. Molecules are desirable in the present invention.

  In addition, even in the case of oligomers and low-molecular liquid crystals, thermal crosslinking, photocrosslinking, etc. in a state where the liquid crystal state or the liquid crystal transition temperature is cooled to below the liquid crystal transition temperature and the orientation is fixed by introducing a crosslinkable group or by blending an appropriate crosslinking agent. Those that can be polymerized by the above means are also included in the liquid crystalline polymer. Even a discotic liquid crystal compound can be used without any problem. As the liquid crystalline polymer, those that exhibit optically positive or negative uniaxiality are usually used.

  Low molecular liquid crystals include Schiff base, biphenyl, terphenyl, ester, thioester, stilbene, tolan, azoxy, azo, phenylcyclohexane, pyrimidine, cyclohexylcyclohexane, trimesic acid, Examples thereof include a low-molecular liquid crystal compound having a triphenylene-based, torquesen-based, phthalocyanine-based, or porphyrin-based molecular skeleton, or a mixture of these compounds.

The Tg of the liquid crystalline composition is preferably room temperature or higher, and more preferably 50 ° C. or higher, because it affects the alignment stability after alignment fixation. Tg can be adjusted by the liquid crystalline polymer used in the liquid crystalline composition, the composition ratio, various compounds added if necessary, and the like, but may be by the crosslinking means as described above.
The various compounds added as necessary may be any compound that does not hinder the alignment of the liquid crystalline composition used in the present invention and does not depart from the purpose of the present invention. Leveling agents, surfactants, stabilizers for uniform formation, and compounds that can promote the reaction of the crosslinkable group under appropriate conditions when the liquid crystalline composition has a crosslinkable group (reaction acceleration Agents), for example, radical generators, cation generators and the like.

Next, the alignment substrate will be described.
Examples of the alignment substrate include thermosetting resins such as polyimide, epoxy resin, and phenol resin, polyamide; polyetherimide; polyetherketone; polyetheretherketone (PEEK); polyketone; polyethersulfone; polyphenylene sulfide; Polyester films such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polyacetals; polycarbonates; poly (meth) acrylates; and polymer films exemplified by thermoplastic resins such as polyvinyl alcohol can be used. Moreover, you may form organic thin films, such as polyvinyl alcohol and a polyimide derivative used as an orientation film, on the surface of a polymer film. The polymer film is subjected to an alignment process such as a rubbing process and is provided on an alignment substrate.

As described above, the rubbing treatment, which is usually subjected to the rubbing treatment to align the liquid crystalline composition on the alignment substrate, can be performed at a predetermined arbitrary angle with respect to the MD direction of the long alignment substrate. . The angle of the rubbing direction with respect to the MD direction is appropriately set according to the function of the optical anisotropic element. However, when the function as a color compensator is required, the rubbing is usually performed obliquely with respect to the MD direction. Is preferred. The angle in the oblique direction is preferably in the range of −45 degrees to +45 degrees.
The rubbing treatment can be performed by an arbitrary method. For example, a rubbing roll is arranged at an arbitrary angle with respect to the MD direction of the long film on a stage that conveys the long film in the MD direction. The rubbing roll is rotated while being conveyed in the MD direction to rub the film surface. The angle formed by the rubbing roll and the moving direction of the stage is a mechanism that can be freely adjusted, and an appropriate rubbing cloth material is stuck on the surface of the rubbing roll.

As a method for forming the liquid crystalline composition layer by bringing the liquid crystalline composition into contact with the rubbing-treated surface of the alignment substrate, for example, a method in which the liquid crystalline composition is dissolved in an appropriate solvent and applied or dried, or a T-die For example, a method of directly melting and extruding the liquid crystalline composition may be used. From the standpoint of film thickness uniformity, a solution coating and drying method is suitable. The method for applying the liquid crystalline composition solution is not particularly limited, and for example, a die coating method, a slot die coating method, a slide die coating method, a roll coating method, a bar coating method, a dip pulling method, or the like can be employed.
After coating, the solvent is removed by an appropriate drying method to form an unoriented liquid crystalline composition layer. Then, after aligning the liquid crystalline composition by heating at a predetermined temperature for a predetermined time, it is cooled to Tg or less, or is crosslinked by a method suitable for the liquid crystalline composition used, for example, light irradiation and / or heat treatment ( The hybrid nematic alignment liquid crystal layer in which the alignment is fixed can be formed by fixing by performing (hardening) or the like.

When crosslinking is performed by light irradiation, light from a light source such as a metal halide lamp, high-pressure mercury lamp, low-pressure mercury lamp, xenon lamp, arc lamp, or laser having a spectrum in the absorption wavelength region of the added reaction accelerator is irradiated. The irradiation amount per square centimeter is usually in the range of 1 to 2000 mJ, preferably 10 to 1000 mJ as the integrated irradiation amount. However, this is not the case when the absorption region of the reaction and the spectrum of the light source are significantly different, or when other components constituting the liquid crystalline composition have the ability to absorb the light source wavelength. In these cases, an appropriate photosensitizer or two or more reaction accelerators having different absorption wavelengths may be mixed and used.
The temperature at the time of light irradiation is preferably in a temperature range in which the liquid crystalline composition takes liquid crystal alignment. In order to sufficiently enhance the crosslinking effect, light irradiation is performed at a temperature equal to or higher than Tg of the liquid crystalline composition. It is preferred to do so.

  That the alignment structure is fixed means that the alignment structure is not disturbed and maintained under the condition of using the elliptically polarizing plate of the present invention. A similar alignment state can be produced in a liquid crystal cell, but fixing the alignment structure eliminates the need for a substrate such as glass in the liquid crystal cell, and can achieve weight reduction, thinning, improved handling, and the like.

Next, the adhesive layer and translucent overcoat layer used in the present invention will be described.
As a material for forming the adhesive layer and the overcoat layer provided on the optical anisotropic element, it has a sufficient adhesive force for a hybrid nematic alignment liquid crystal layer, a polarizing element and a translucent protective film described later, As long as the optical properties of the materials are not impaired, there is no particular limitation. For example, acrylic resin, methacrylic resin, epoxy resin, ethylene-vinyl acetate copolymer, rubber, urethane, polyvinyl ether And various reactive types such as thermosetting type and / or photocuring type and electron beam curable type. These adhesive layers include those having the function of a transparent protective layer (overcoat layer) that protects the hybrid nematic alignment liquid crystal layer. A pressure-sensitive adhesive can be used as the adhesive.

Since the reaction (curing) conditions for the reactive substances vary depending on the components constituting the adhesive, the viscosity, the reaction temperature, and the like, the conditions suitable for each may be selected. For example, in the case of a photo-curing type, various known photoinitiators are preferably added, and light from a light source such as a metal halide lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, a xenon lamp, an arc lamp, a laser, or a synchrotron radiation source is used. Irradiation may be performed to cause the reaction. The amount of irradiation per unit area (one square centimeter) is usually in the range of 1 to 2000 mJ, preferably 10 to 1000 mJ as the integrated irradiation amount. However, this is not the case when the absorption region of the photoinitiator and the spectrum of the light source are significantly different, or when the reactive compound itself has the ability to absorb the light source wavelength. In these cases, an appropriate photosensitizer or a method of using a mixture of two or more photoinitiators having different absorption wavelengths can be used. The acceleration voltage in the case of the electron beam curable type is usually 10 kV to 200 kV, preferably 50 kV to 100 kV.
The thickness of the adhesive layer and the overcoat layer varies depending on the components constituting the adhesive, the strength of the adhesive, the operating temperature, etc. as described above, but is usually 1 to 30 μm, more preferably 3 to 10 μm. Outside this range, the adhesive strength is insufficient, or bleeding from the end is not preferable.

These adhesives can also contain various fine particles and surface modifiers for the purpose of controlling the optical properties or controlling the peelability and erosion properties of the substrate as long as the properties are not impaired.
Examples of the fine particles include fine particles having a refractive index different from that of the compound constituting the adhesive, conductive fine particles for improving antistatic performance without impairing transparency, and fine particles for improving wear resistance. Specifically, fine silica, fine alumina, ITO (Indium Tin Oxide) fine particles, silver fine particles, various synthetic resin fine particles and the like can be mentioned.

The surface modifier is not particularly limited as long as it has good compatibility with the adhesive and does not affect the curability of the adhesive or the optical performance after curing, and is an ionic or nonionic water-soluble interface. Activators, oil-soluble surfactants, polymer surfactants, fluorosurfactants, organometallic surfactants such as silicone, reactive surfactants, and the like can be used. In particular, fluorine-based surfactants such as perfluoroalkyl compounds and perfluoropolyether compounds, and organometallic surfactants such as silicone are particularly desirable because they have a large surface modification effect. The addition amount of the surface modifier is desirably in the range of 0.01 to 10% by mass with respect to the adhesive, more desirably 0.05 to 5% by mass, and further desirably 0.1 to 3% by mass. If the amount added is less than this range, the effect of addition becomes insufficient. On the other hand, if the amount added is too large, there is a risk of adverse effects such as an excessive decrease in adhesive strength. In addition, a surface modifier may be used independently and may use multiple types together as needed.
Furthermore, you may mix | blend various additives, such as antioxidant and a ultraviolet absorber, in the range which does not impair the effect of this invention.

  The polarizing element that can be used in the present invention is not particularly limited, and various types can be used. Examples of polarizing elements include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films, and two colors such as iodine and dichroic dyes. And polyene-based oriented films such as a product obtained by adsorbing a reactive substance and a dehydrochlorinated product of polyvinyl chloride. Among these, those obtained by stretching a polyvinyl alcohol film and adsorbing and orienting a dichroic material (iodine, dye) are preferably used. The thickness of the polarizing element is not particularly limited, but is generally about 5 to 50 μm.

  A polarizing element in which a polyvinyl alcohol film is dyed with iodine and uniaxially stretched can be produced by, for example, dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution of boric acid or potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring 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.

  As the translucent protective film provided on one surface of the polarizing element, an optically isotropic film is preferable. For example, triacetyl such as Fujitac (product of Fuji Photo Film) or Konicatak (product of Konica Minolta Opto). Cycloolefin polymers such as cellulose (TAC) film, arton film (product of JSR), ZEONOR film, ZEONEX film (product of ZEON CORPORATION), TPX film (product of Mitsui Chemicals), acrylene film (product of Mitsubishi Rayon) ) And the like, but triacetyl cellulose and cycloolefin polymers are preferred from the viewpoint of flatness, heat resistance and moisture resistance when an elliptically polarizing plate is used. In general, the thickness of the translucent protective film is preferably 1 to 100 μm, particularly preferably 5 to 50 μm.

As the light-transmitting protective film, a film having a hard coat layer, antireflection treatment, antisticking, or treatment for diffusion or antiglare on the surface can be used.
Hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured film having excellent hardness and slipping properties with an appropriate ultraviolet curable resin such as acrylic or silicone is applied to the protective film. It can be formed by a method of adding to the surface. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a blending method of transparent particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a light diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.
The antireflection layer, anti-sticking layer, light diffusion layer, antiglare layer, etc. can be provided on the translucent protective film itself, and separately from the translucent protective film layer as a separate optical layer. It can also be provided.

Next, the manufacturing method of the elliptically polarizing plate of this invention is demonstrated in detail.
The layer structure of the elliptically polarizing plate obtained by the present invention is selected from the following two types as shown in FIGS.
(I) Translucent protective film / adhesive layer 1 / polarizing element / adhesive layer 2 / optical anisotropic element (II) Translucent protective film / adhesive layer 1 / polarizing element / optical anisotropic element

Although it does not specifically limit as a manufacturing method of an elliptically polarizing plate, It can manufacture with the following method as an example.
First, the manufacturing method of structure (I) is demonstrated.
Configuration (I) is
(1) First step of obtaining a laminate (A) comprising a translucent protective film / adhesive layer 1 / polarizing element by adhering the translucent protective film to the polarizing element via the adhesive layer 1;
(2) A layer of a liquid crystalline composition exhibiting at least positive uniaxiality is formed on an alignment substrate that has been subjected to rubbing treatment, and the layer is hybrid nematically aligned, and then an optically anisotropic element in which the alignment is fixed is formed. A second step of forming a laminate (B) comprising an alignment substrate / optically anisotropic element,
(3) After the optically anisotropic element side of the laminate (B) is adhered to the polarizing element side of the laminate (A) via the adhesive layer 2, the alignment substrate is peeled off to optically anisotropic. A third step of transferring the element to the laminate (A) and obtaining an elliptically polarizing plate comprising a translucent protective film / adhesive layer 1 / polarizing element / adhesive layer 2 / optically anisotropic element;
It is characterized by passing through each process of at least.

Hereinafter, the manufacturing method from the 1st process to the 3rd process is explained in order.
First, the manufacturing method of the laminated body (A) which is a 1st process is demonstrated.
An adhesive layer 1 is formed on the polarizing element, and the light-transmitting protective film and the polarizing element are brought into close contact with each other via the adhesive layer 1, and then the adhesive layer is reacted (cured) as necessary. Thus, a laminate (A) bonded on the translucent protective film via the adhesive layer 1 can be obtained.

Subsequently, the manufacturing method of the laminated body (B) which is a 2nd process is demonstrated.
After rubbing the alignment substrate with a cloth or the like, a coating layer of a liquid crystalline composition exhibiting at least positive uniaxiality is formed by an appropriate method, and if necessary, the solvent is removed, and heating is performed. The liquid crystalline composition is hybrid nematically aligned, and the alignment of the liquid crystalline composition layer is fixed by means suitable for the liquid crystalline composition used. Thus, a laminate (B) having an optical anisotropic element composed of a hybrid nematic alignment liquid crystal layer in which hybrid nematic alignment is fixed on an alignment substrate can be obtained.

Next, the manufacturing method in the third step will be described.
After the optically anisotropic element side of the laminate (B) is in close contact with the polarizing element side of the laminate (A) via the adhesive layer 2, the adhesive layer is reacted (cured) as necessary. Then, the alignment substrate is peeled off and the optical anisotropic element is transferred to the laminate (A).
Thus, the elliptically polarizing plate of the present invention consisting of a translucent protective film / adhesive layer 1 / polarizing element / adhesive layer 2 / optically anisotropic element is obtained.

When transferring the twisted nematic alignment liquid crystal layer to the laminate (A) of the laminate (B), if necessary, the twist nematic alignment liquid crystal layer is transferred to another substrate different from the alignment substrate, and then the laminate (A ) May be retransferred to.
In order to protect the surface of the optically anisotropic element of the obtained elliptically polarizing plate, a translucent overcoat layer may be provided, or a temporary surface protective film may be bonded. Here, the translucent overcoat can also be selected from the aforementioned adhesives.

Next, a manufacturing method of the configuration (II) will be described.
Configuration (II) is
(1) First step of obtaining a laminate (A) comprising a translucent protective film / adhesive layer 1 / polarizing element by adhering the translucent protective film to the polarizing element via the adhesive layer 1;
(2) A rubbing treatment is performed on the polarizing element of the laminate (A) to form a layer of a liquid crystalline composition exhibiting at least positive uniaxiality, and the layer is hybrid nematically oriented, and then the orientation is fixed. A second step of forming an optically anisotropic element and obtaining an elliptically polarizing plate comprising a translucent protective film / adhesive layer 1 / polarizing element / optically anisotropic element;
It is characterized by passing through each process of at least.

Hereinafter, the manufacturing method from the first step to the second step will be described in order.
First, the manufacturing method of the laminated body (A) which is a 1st process is the same as that of a structure (I).
The manufacturing method in the second step will be described.
A rubbing treatment is performed on the polarizing element of the laminate (A) produced in the first step, and a coating layer of a liquid crystalline composition exhibiting at least positive uniaxiality is formed by an appropriate method. The liquid crystal composition is hybrid nematically aligned by heating or the like, and the hybrid nematic alignment of the liquid crystal composition is fixed by means suitable for the liquid crystal composition used. Thus, the laminate (A) has an optical anisotropic element composed of a hybrid nematic alignment liquid crystal layer in which the hybrid nematic liquid crystal alignment is fixed, and consists of a translucent protective film / adhesive layer 1 / polarization element / optical anisotropic element. The elliptically polarizing plate of the present invention having a configuration can be obtained.

In order to protect the surface of the optically anisotropic element of the obtained elliptically polarizing plate, a translucent overcoat layer may be provided, or a temporary surface protective film may be bonded. Here, the translucent overcoat can also be selected from the aforementioned adhesives.
In the second step of the configuration (II), depending on the orientation of the polarizing element with respect to the liquid crystalline composition, a rubbing may be performed after providing an appropriate alignment film that nematically aligns the liquid crystalline composition. The method of forming a layer of a liquid crystalline composition by applying the method is also included in the present invention (FIG. 6).
In the present invention, it is also possible to laminate a plurality of hybrid nematic alignment liquid crystal layers by repeatedly laminating a hybrid nematic alignment liquid crystal layer on an alignment substrate via an adhesive layer or an adhesive layer.

Although a translucent protective film is bonded with a polarizing element, it is preferable to surface-treat a translucent protective film, a polarizing element, or the said laminated body (A) before bonding.
For the surface treatment, a method suitable for a light-transmitting protective film or a polarizing element may be used. Examples of such a method include saponification treatment, corona discharge treatment, flame treatment, low-pressure UV irradiation, plasma treatment, and the like. Preferably, saponification treatment is preferable when, for example, triacetylcellulose is used as the translucent protective film, and corona discharge treatment is preferable when a cycloolefin polymer is used. In the polarizing element, corona discharge treatment is preferable.

The saponification treatment is performed by contacting with an alkaline aqueous solution, which is a normal method. As the alkaline aqueous solution, potassium hydroxide, sodium hydroxide or the like is used, and the alkali concentration is about 0.1 to 10% by mass, preferably about 0.5 to 5% by mass, more preferably about 1 to 3%. A dilute solution on the order of mass is sufficient. As treatment conditions, mild conditions of 1 to 60 minutes at room temperature, preferably 30 minutes or less, more preferably 15 minutes or less are sufficient. Needless to say, it is necessary to thoroughly wash with water after the treatment.
Similar to the above saponification treatment, the corona discharge treatment may be performed under ordinary conditions, for example, on the isotropic substrate surface in contact with the pressure-sensitive adhesive layer. The processing conditions vary depending on the type of substrate and corona processing apparatus to be used. For example, the energy density is preferably 1 to 300 W · min / m ² . The surface tension is increased by performing the corona discharge treatment, but it is desirable to increase the surface tension to 40 dyn / cm or more.

The optically anisotropic element, the polarizing element and the translucent protective film can be laminated in a continuous manner in the state of being aligned in the MD direction in the form of a long film when bonded.
Further, in addition to the manufacturing method, these three members can apply an optical anisotropic element and a light-transmitting protection to the polarizing element even if the optical anisotropic element and the light-transmitting protective film are simultaneously bonded to both sides of the polarizing element. You may bond in the order of a film, or the order of a translucent protective film and an optically anisotropic element.

  The total thickness of the elliptically polarizing plate of the present invention thus obtained varies depending on the thickness of the translucent protective film, polarizing element, adhesive, optical anisotropic element, etc. used, but is 150 μm or less, preferably 100 μm or less. Good. If the total thickness exceeds 150 μm, the roll diameter becomes too large when a long film is wound around the roll for a predetermined length, making it difficult to store in a conventional transport packaging container, or long if it can be stored in a conventional transport container. It is not preferable because the length becomes shorter.

Further, an elliptically polarizing plate in which at least one optical film is further laminated on the elliptically polarizing plate of the present invention may be used.
Although it will not restrict | limit especially if it is excellent in transparency and uniformity as an optical film, The liquid crystalline film which consists of a polymer stretched film and a liquid crystal can be used preferably. Examples of the stretched polymer film include a uniaxial or biaxial retardation film composed of a cellulose-based, polycarbonate-based, polyarylate-based, polysulfone-based, polyacryl-based, polyethersulfone-based, cyclic olefin-based polymer, or the like. Can do. Of these, polycarbonate and cyclic olefin polymers are preferred from the viewpoint of cost and film uniformity.

In addition, the liquid crystalline film made of liquid crystal here is not particularly limited as long as it is a film that can utilize the optical anisotropy generated from the alignment state by aligning the liquid crystal. For example, known materials such as various optical functional films using nematic liquid crystal, discotic liquid crystal, smectic liquid crystal and the like can be used.
The molecular alignment structure of the liquid crystalline film may be any of the molecular alignment structures such as smectic, nematic, twisted nematic, and cholesteric, and is in a homogeneous alignment and homeotropic alignment near the alignment substrate and near the air interface, respectively. A so-called hybrid orientation in which the average director of the polymer is inclined from the normal direction of the film may be used.
The optical film exemplified here may be used alone or in a plurality of sheets in constituting a liquid crystal display device. Moreover, both a polymer stretched film and a liquid crystalline film can be used.

Hereinafter, a liquid crystal display device to which the elliptically polarizing plate of the present invention is applied will be described.
The liquid crystal display device of the present invention has at least the elliptically polarizing plate. When the elliptically polarizing plate of the present invention is disposed in a liquid crystal cell, it is necessary to dispose the elliptically polarizing plate of the present invention so that the optically anisotropic element side is close to the liquid crystal cell surface.
A liquid crystal display device is generally composed of a polarizing plate, a liquid crystal cell, and a member such as a retardation compensation plate, a reflection layer, a light diffusion layer, a backlight, a front light, a light control film, a light guide plate, and a prism sheet as necessary. Although comprised, in this invention, there is no restriction | limiting in particular except the point which uses the said elliptically polarizing plate. Further, the use position of the elliptically polarizing plate is not particularly limited, and may be one place or a plurality of places.

The polarizing plate used for the liquid crystal display device is not particularly limited, and those obtained from the same polarizing element as those used for the elliptically polarizing plate described above can be used.
The liquid crystal cell is not particularly limited, and a general liquid crystal cell such as a liquid crystal layer sandwiched between a pair of transparent substrates provided with electrodes can be used.
The transparent substrate constituting the liquid crystal cell is not particularly limited as long as the liquid crystal material constituting the liquid crystal layer is aligned in a specific alignment direction. Specifically, a transparent substrate in which the substrate itself has a property of orienting liquid crystals, a transparent substrate in which an alignment film having the property of orienting liquid crystals is provided, but the substrate itself lacks the alignment ability. Either can be used. Moreover, a well-known thing can be used for the electrode of a liquid crystal cell. Usually, it can be provided on the surface of the transparent substrate in contact with the liquid crystal layer, and when a substrate having an alignment film is used, it can be provided between the substrate and the alignment film.
The material exhibiting liquid crystallinity for forming the liquid crystal layer is not particularly limited, and examples thereof include various ordinary low-molecular liquid crystal substances, high-molecular liquid crystal substances, and mixtures thereof that can constitute various liquid crystal cells. In addition, a dye, a chiral agent, a non-liquid crystal substance, or the like can be added to these as long as liquid crystallinity is not impaired.

In addition to the electrode substrate and the liquid crystal layer, the liquid crystal cell may include various components necessary to form various types of liquid crystal cells described later.
As liquid crystal cell methods, TN (Twisted Nematic) method, STN (Super Twisted Nematic) method, ECB (Electrically Controlled Birefringence) method, IPS (In-Plane Switching) method, VA (Vertical Alignment) method, OCB (Optically Compensated) Birefringence method, HAN (Hybrid Aligned Nematic) method, ASM (Axially Symmetric Aligned Microcell) method, halftone gray scale method, domain division method, display method using ferroelectric liquid crystal, anti-ferroelectric liquid crystal, etc. The method is mentioned.
Further, the driving method of the liquid crystal cell is not particularly limited, and a passive matrix method used for STN-LCD and the like, and an active matrix method using active electrodes such as TFT (Thin Film Transistor) electrodes and TFD (Thin Film Diode) electrodes, Any driving method such as a plasma addressing method may be used.

The retardation compensator can be appropriately selected from the optical films used in the present invention and can be used alone or in combination. Further, both a polymer stretched film and an optical compensation film made of liquid crystal can be used.
The reflective layer is not particularly limited, and is a metal such as aluminum, silver, gold, chromium, or platinum, an alloy containing them, an oxide such as magnesium oxide, a dielectric multilayer film, a liquid crystal exhibiting selective reflection, or a combination thereof. Etc. can be illustrated. These reflective layers may be flat or curved. In addition, the reflective layer is processed to have a surface shape, such as a concavo-convex shape, to have diffuse reflectivity, the liquid crystal cell has electrodes on the electrode substrate opposite to the viewer side, and the thickness of the reflective layer is It may be a transflective layer that transmits light partially by thinning or drilling holes, or a combination thereof.

The light diffusion layer is not particularly limited as long as it has a property of diffusing incident light isotropically or anisotropically. For example, it may be composed of two or more regions, with a difference in refractive index between the regions, or with surface irregularities. Examples of the two or more regions having a refractive index difference between the regions include those in which particles having a refractive index different from that of the matrix are dispersed in the matrix. The light diffusing layer itself may have adhesiveness.
The film thickness of the light diffusing layer is not particularly limited, but is usually preferably 10 μm or more and 500 μm or less.
Further, the total light transmittance of the light diffusion layer is preferably 50% or more, and particularly preferably 70% or more. Furthermore, the haze value of the light diffusion layer is usually 10 to 95%, preferably 40 to 90%, and more preferably 60 to 90%.
The backlight, the front light, the light control film, the light guide plate, and the prism sheet are not particularly limited, and known ones can be used.

  The liquid crystal display device of the present invention can be provided with other constituent members in addition to the constituent members described above. For example, by attaching a color filter to the liquid crystal display device of the present invention, a color liquid crystal display device capable of performing multicolor or full color display with high color purity can be manufactured.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
In addition, each analysis method used in the Example is as follows. Further, Δn · d is a value at a wavelength of 550 nm unless otherwise specified.

(1) Measurement of logarithmic viscosity Using an Ubbelohde viscometer, it was measured at 30 ° C. in a phenol / tetrachloroethane (60/40 mass ratio) mixed solvent.
(2) Microscope observation The alignment state of the liquid crystal was observed with an Olympus BH2 polarizing microscope.
(3) Parameter measurement of hybrid nematic alignment liquid crystal layer An automatic birefringence meter KOBRA21ADH manufactured by Oji Scientific Instruments was used.
(4) Measurement of film thickness A SURFACE TEXTURE ANALYSIS SYSTEM Dektak 3030ST manufactured by SLOAN was used. Moreover, the method of calculating | requiring a film thickness from the data of interference wave measurement (The JASCO Corporation UV / visible / near infrared spectrophotometer V-570) and refractive index data was used together.

<Example 1>
(Preparation of laminate A)
A TAC film (40 μm, manufactured by Fuji Photo Film Co., Ltd.) was immersed in a 2% by mass aqueous potassium hydroxide solution for 5 minutes at room temperature, saponified, washed in running water, and dried. A saponified TAC film was bonded to one surface of a polarizing element in which iodine was adsorbed to stretched polyvinyl alcohol, using an acrylic adhesive as the adhesive layer 1, and a laminate A was produced. The total film thickness was about 65 μm, which was thinner than the normal one (105 μm).

(Preparation of liquid crystalline polymer solution B, laminate D)
An acetylation reaction was performed at 140 ° C. for 2 hours in a nitrogen atmosphere using 6-hydroxy-2-naphthoic acid 100 mmol, terephthalic acid 100 mmol, chlorohydroquinone 50 mmol, tert-butylcatechol 50 mmol, and acetic anhydride 600 mmol. Subsequently, polymerization was carried out at 270 ° C. for 2 hours, at 280 ° C. for 2 hours, and at 300 ° C. for 2 hours. Next, the obtained reaction product was dissolved in tetrachloroethane, and then purified by reprecipitation with methanol to obtain 40.0 g of a liquid crystalline polyester (polymer 1). This liquid crystalline polyester had a logarithmic viscosity of 0.35 (dl / g), a nematic phase as a liquid crystal phase, an isotropic phase-liquid crystal phase transition temperature of 300 ° C. or higher, and a glass transition point of 135 ° C.
An 8% by mass γ-butyrolactone solution (Liquid Crystalline Polymer Solution B) of polymer 1 was prepared.

  While conveying a long PEEK film with a width of 650 mm and a thickness of 100 μm, a 150 mmφ rubbing roll wrapped with a rayon cloth is set at an angle, and is continuously rubbed by rotating at a high speed, with a rubbing angle of 45 °. A substrate film was obtained. Here, the rubbing angle is an angle in the counterclockwise direction from the MD direction when the rubbing surface is viewed from above. The liquid crystalline polymer solution B is continuously applied and dried on the oriented substrate film using a die coater, and then heat-treated at 150 ° C. for 10 minutes to orient the liquid crystalline polymer, and then at room temperature. The alignment was fixed by cooling to obtain a laminate D composed of a liquid crystalline polymer layer and a PEEK film. The thickness of the obtained laminate D was 0.6 μm.

Since the PEEK film used as the alignment substrate has a large birefringence, it is difficult to measure the optical parameters of the liquid crystalline polymer layer in the form of the laminate D. Therefore, on the triacetyl cellulose (TAC) film as follows. The liquid crystalline polymer layer was transferred.
That is, an optical ultraviolet curable adhesive is applied on the liquid crystalline polymer layer on the PEEK film so as to have a thickness of 5 μm, and is laminated with a TAC film (40 μm thickness, manufactured by Fuji Photo Film Co., Ltd.). After irradiating ultraviolet rays from the film side to cure the adhesive, the PEEK film was peeled off to obtain a laminate composed of a liquid crystalline polymer layer / adhesive layer / TAC film. The obtained laminate was subjected to parameter measurement using an automatic birefringence meter KOBRA21ADH manufactured by Oji Scientific Instruments Co., Ltd. As a result, this liquid crystalline polymer layer had a hybrid nematic alignment structure, and Δnd of the layer was 90 nm, average The tilt angle was 28 degrees.

(Preparation of elliptically polarizing plate E)
A commercially available UV curable adhesive (UV-3400, manufactured by Toagosei Co., Ltd.) was applied on the liquid crystal polymer layer (optical anisotropic element) of the laminate D as an adhesive layer 2 to a thickness of 5 μm. On this, the polarizing element side of the laminate A was laminated, and the adhesive layer 2 was cured by UV irradiation of about 600 mJ. After that, the PEEK film is peeled off from the laminate in which the PEEK film / optical anisotropic / adhesive layer 2 / polarizing element / adhesive layer 1 / TAC film is integrated so that the optical anisotropic element is placed on the laminate A. Then, an elliptically polarizing plate E composed of TAC film / adhesive layer 1 / polarizing element / adhesive layer 2 / optically anisotropic element was obtained. The total thickness of the elliptically polarizing plate E was 75 μm.
When this elliptically polarizing plate E was optically inspected, no damage such as spots or scratches was found. When the optically anisotropic element side of the elliptically polarizing plate E is attached to a glass plate via an acrylic adhesive, it is placed in a constant temperature and humidity chamber at 60 ° C. and 90% RH, taken out after 500 hours, and observed. No abnormalities such as bubbles were observed.

<Example 2>
(Preparation of adhesive)
As urethane-based adhesive, 100 parts of “EL-436A” (an aqueous solution with a solid content of 35%) manufactured by Toyo Morton Co., Ltd., which is a polyester polyol prepolymer as the main agent, is used as Toyo Morton Co., Ltd., an isocyanate curing agent. 30 parts of “EL-436B” (100% active ingredient) was added, and further diluted with water to a solid content concentration of 20%. On the other hand, as a polyvinyl alcohol-based adhesive, a carboxyl group-modified polyvinyl alcohol “Kuraray Poval KL318” manufactured by Kuraray Co., Ltd. (a saponification product of a copolymer having a molar ratio of vinyl acetate and sodium itaconate of about 98: 2, saponification degree) A 3% aqueous solution having a molecular weight of about 85,000 was prepared. The obtained urethane adhesive and polyvinyl alcohol aqueous solution were mixed at a mass ratio of 1: 1 (20: 3 in terms of solid content mass ratio) to obtain a mixed adhesive.

(Preparation of laminate F)
The mixed adhesive prepared as the adhesive layer 1 was applied within one minute after mixing on one surface of the polarizing element in which iodine was adsorbed to the stretched polyvinyl alcohol, and a ZEONOR film (film thickness) was applied to the one surface. 40 μm, manufactured by Nippon Zeon Co., Ltd.) was subjected to a corona treatment under the condition of 250 W · min / m ² , and bonded to the corona-treated surface within 30 seconds after the corona treatment to produce a laminate F of the present invention. The total film thickness was about 65 μm, which was thinner than the normal one (105 μm).

(Preparation of elliptical polarizing plate G)
A commercially available UV curable adhesive (UV-3400, manufactured by Toagosei Co., Ltd.) was applied as an adhesive layer 2 to a thickness of 5 μm on the optically anisotropic element of the laminate D produced in Example 1. The polarizing element side of the laminate F was laminated thereon, and the adhesive layer 2 was cured by UV irradiation of about 600 mJ. Thereafter, the PEEK film is peeled off from the laminate in which the PEEK film / optically anisotropic element / adhesive layer 2 / polarizing element / adhesive 1 / Zeonor film is integrated, so that the optical anisotropic element is placed on the laminate F. Then, an elliptically polarizing plate G composed of ZEONOR film / adhesive layer 1 / polarizing element / adhesive layer 2 / optically anisotropic element was obtained. The total thickness of the elliptically polarizing plate G was 75 μm.
When this circularly polarizing plate G was optically inspected, no damage such as spots or scratches was found. When the optically anisotropic element side of the elliptically polarizing plate G is attached to a glass plate via an acrylic adhesive, it is placed in a constant temperature and humidity chamber at 60 ° C. and 90% RH, and is taken out and observed after 500 hours. No abnormalities such as bubbles were observed.

<Example 3>
(Preparation of elliptical polarizing plate H)
An oriented substrate film having a rubbing angle of 45 ° is formed by continuously rubbing by rotating a high-speed rotating 150 mmφ rubbing roll wrapped with a rayon cloth while transporting the laminate F produced in Example 2. Got. Here, the rubbing angle is an angle in the counterclockwise direction from the MD direction when the rubbing surface is viewed from above. The liquid crystalline polymer solution B prepared in Example 1 was continuously applied and dried at a coating rate different from that in Example 1 using a die coater, and then heat-treated at 150 ° C. for 10 minutes. Were oriented. Next, the film was cooled to room temperature and the orientation was fixed to obtain an elliptically polarizing plate H (Zeonor film / adhesive layer 1 / polarizing element / optical anisotropic element) having an optical anisotropic element composed of a liquid crystalline polymer layer. The total thickness of the elliptically polarizing plate H was 70 μm.
As in Example 1, when only the liquid crystalline polymer layer was transferred to the TAC film and the optical parameters were measured, this polymer liquid crystal layer formed a hybrid nematic alignment structure. Δnd was 90 nm, and the average tilt angle was 28 degrees.
When this elliptical polarizing plate H was optically inspected, no damage such as spots or scratches was found. When the optically anisotropic element side of the elliptically polarizing plate H is attached to a glass plate via an acrylic adhesive, it is placed in a constant temperature and humidity chamber at 60 ° C. and 90% RH, and is taken out and observed after 500 hours. No abnormalities such as bubbles were observed.

<Example 4>
(Preparation of laminate I)
While being transported onto the laminate F produced in Example 2, a 5 mass% solution of polyvinyl alcohol (PVA, manufactured by Kuraray Co., Ltd., PVA-117H) (the solvent has a mass ratio of water to isopropyl alcohol of 1: 1). The mixed solvent) was continuously applied and dried using a die coater, and heat-treated at 130 ° C. to obtain a laminate I composed of zeonore film / adhesive layer 1 / polarizing element / PVA alignment film.
(Preparation of elliptical polarizing plate J)
While transporting the prepared laminate I, a 150 mmφ rubbing roll with a rayon cloth wrapped around the PVA alignment film surface is set obliquely and rotated at a high speed to perform continuous rubbing, with a rubbing angle of 45 °. A substrate film was obtained. Here, the rubbing angle is an angle in the counterclockwise direction from the MD direction when the rubbing surface is viewed from above. The liquid crystalline polymer solution B prepared in Example 1 was continuously applied and dried in the same manner as in Example 3 using a die coater, and then heat-treated at 150 ° C. for 10 minutes to align the liquid crystalline polymer. I let you. Next, it is cooled to room temperature to fix the alignment, and an elliptically polarizing plate J having an optical anisotropic element composed of a liquid crystalline polymer layer (Zeonor film / adhesive layer 1 / polarizing element / PVA alignment film / optical anisotropic element) Got. The total thickness of the elliptically polarizing plate J was 73 μm.
When this elliptically polarizing plate J was optically inspected, no damage such as spots or scratches was found. When the optically anisotropic element side of the elliptically polarizing plate J is attached to a glass plate via an acrylic adhesive, it is placed in a constant temperature and humidity chamber at 60 ° C. and 90% RH, and is taken out and observed after 500 hours. No abnormalities such as bubbles were observed.

<Comparative Example 1>
(Preparation of polarizing plate M)
A polarizing plate M was prepared by attaching a saponified TAC film to both sides of a polarizing element in which iodine was adsorbed to stretched polyvinyl alcohol using an acrylic adhesive.
(Preparation of laminate L)
The optically anisotropic element side of the laminate D produced in Example 1 was transferred to a triacetyl cellulose (TAC) film (40 μm) via an ultraviolet curable adhesive. That is, after applying an adhesive to a thickness of 5 μm on the liquid crystalline polymer layer on the PEEK film, laminating with a TAC film, and irradiating ultraviolet rays from the TAC film side to cure the adhesive The PEEK film was peeled off to obtain a laminate L (optical anisotropic element / adhesive layer / TAC film).
(Preparation of elliptical polarizing plate N)
A polarizing plate M was prepared by attaching a saponified TAC film to both sides of a polarizing element in which iodine was adsorbed to stretched polyvinyl alcohol using an acrylic adhesive.
The optically anisotropic element side of the laminate L was bonded to the polarizing plate M via an acrylic pressure-sensitive adhesive to produce an elliptical polarizing plate N. Since this elliptically polarizing plate N is as thick as about 200 μm and the winding thickness becomes large, the processing length in one operation must be shorter than the preparation of the elliptically polarizing plates of Examples 1 to 4. It was.
When an acrylic pressure-sensitive adhesive was applied to the optically anisotropic element side of the elliptically polarizing plate N and attached to a glass plate, the same test as in Example 1 was performed. After 500 hours had elapsed, 0.5 mm was peeled off at the end. Was recognized.

<Example 5>
Using the elliptically polarizing plate E obtained in Example 1, a transmissive liquid crystal display device was produced in an arrangement as shown in FIG.
The liquid crystal cell 10 used was homogeneously aligned using ZLI-1695 (manufactured by Merck) as the liquid crystal material. The thickness of the liquid crystal layer was 4.9 μm, the pretilt angle at both interfaces of the substrate of the liquid crystal layer was 2 degrees, and the Δnd of the liquid crystal cell was about 320 nm.
A polarizing plate 8 (thickness: about 100 μm; SQW-062 manufactured by Sumitomo Chemical Co., Ltd.) is disposed on the viewer side (upper side of the drawing) of the liquid crystal cell 10, and uniaxially stretched between the polarizing plate 8 and the liquid crystal cell 10. A retardation compensation plate 9 made of a polycarbonate film (manufactured by Nippon Zeon Co., Ltd .: Δnd is approximately 140 nm) was disposed.
Further, the elliptically polarizing plate E (referred to as 1 in FIG. 7) obtained in Example 1 was disposed on the backlight side (lower side of the figure) of the liquid crystal cell.
The absorption axes of the polarizing plate 8 and the polarizing element 4, the slow axis of the retardation compensation plate 9, the pretilt direction of both interfaces of the liquid crystal cell 10, and the tilt direction of the optical anisotropic element 6 were arranged under the conditions shown in FIG. A backlight 11 is provided on the back side of the elliptically polarizing plate 1.
When the driving voltage (0 V to 5 V) is applied from the driving circuit (not shown) to the liquid crystal display device described above, the backlight 11 is arranged and the optical characteristics during lighting (transmission mode) are examined. It was found that characteristics with little angular dependence were obtained.

It is a conceptual diagram for demonstrating the tilt angle and twist angle of a liquid crystal molecule. It is a conceptual diagram of the orientation structure of the liquid crystalline film which comprises an optically anisotropic element. It is a conceptual diagram explaining the pretilt direction of a liquid crystal cell. It is an elevation sectional view showing typically the example of composition of the elliptically polarizing plate of the present invention. It is an elevation sectional view showing typically another example of composition of the elliptically polarizing plate of the present invention. It is an elevation sectional view showing typically another example of composition of the elliptically polarizing plate of the present invention. 6 is a conceptual diagram of a liquid crystal display used in Example 4. FIG. FIG. 10 is a plan view illustrating an absorption axis of a polarizing plate, a liquid crystal cell, and an axial angle relationship of an optically anisotropic layer in the liquid crystal display device of Example 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elliptical polarizing plate 2 Translucent protective film 3 Adhesive layer 1
4 Polarizing element 5 Adhesive layer 2
6 Optical anisotropic element 7 Alignment film 8 Polarizing plate 9 Phase difference compensation plate 10 Liquid crystal cell 11 Backlight

Claims (22)

  A translucent protective film, a polarizing element and an optically anisotropic element are elliptically polarizing plates laminated in this order, and the liquid crystalline composition in which the optically anisotropic element exhibits at least positive uniaxiality in a liquid crystal state An elliptically polarizing plate comprising a hybrid nematic alignment liquid crystal layer in which the alignment is fixed after hybrid nematic alignment.   The elliptically polarizing plate according to claim 1, wherein the translucent protective film, the polarizing element and the optical anisotropic element are in the form of a long film.   The optical anisotropic element is composed of at least a hybrid nematic alignment layer, the liquid crystal layer has an average tilt angle of 5 ° to 45 °, a refractive index anisotropy Δn at a wavelength of 550 nm, and a thickness d of the optical anisotropic body. The elliptically polarizing plate according to claim 1, wherein the product (Δn · d) is in a range of 30 nm to 200 nm.   4. The elliptically polarizing plate according to claim 1, wherein the translucent protective film is triacetyl cellulose.   The elliptically polarizing plate according to claim 1, wherein the translucent protective film is a cycloolefin polymer.   The elliptically polarizing plate according to claim 1, wherein the elliptically polarizing plate has a thickness of 150 μm or less.   The elliptically polarizing plate according to claim 1, wherein an alignment film in which the liquid crystalline composition forms a nematic alignment is provided between the polarizing element and the optical anisotropic element.   The elliptically polarizing plate according to claim 1, wherein a translucent overcoat layer is provided on a surface of the optically anisotropic element opposite to the polarizing element.   The elliptically polarizing plate according to claim 8, wherein the translucent overcoat layer is made of an acrylic resin.   An elliptically polarizing plate, further comprising at least one optical film laminated on the elliptically polarizing plate according to claim 1.   The elliptically polarizing plate according to claim 10, wherein the optical film is a polymer stretched film.   The elliptically polarizing plate according to claim 10, wherein the optical film is a liquid crystalline film. (1) First step of obtaining a laminate (A) comprising a translucent protective film / adhesive layer 1 / polarizing element by adhering the translucent protective film to the polarizing element via the adhesive layer 1;
(2) A layer of a liquid crystalline composition exhibiting at least positive uniaxiality is formed on an alignment substrate that has been subjected to rubbing treatment, and the layer is hybrid nematically aligned, and then an optically anisotropic element in which the alignment is fixed is formed. A second step of forming a laminate (B) comprising an alignment substrate / optically anisotropic element,
(3) After the optically anisotropic element side of the laminate (B) is adhered to the polarizing element side of the laminate (A) via the adhesive layer 2, the alignment substrate is peeled off to optically anisotropic. A third step of transferring the element to the laminate (A) and obtaining an elliptically polarizing plate comprising a translucent protective film / adhesive layer 1 / polarizing element / adhesive layer 2 / optically anisotropic element;
The manufacturing method of the elliptically polarizing plate characterized by passing through each process of these. (1) First step of obtaining a laminate (A) comprising a translucent protective film / adhesive layer 1 / polarizing element by adhering the translucent protective film to the polarizing element via the adhesive layer 1;
(2) A rubbing treatment is performed on the polarizing element of the laminate (A) to form a layer of a liquid crystalline composition exhibiting at least positive uniaxiality, and the layer is hybrid nematically oriented, and then the orientation is fixed. A second step of forming an optically anisotropic element to obtain an elliptically polarizing plate comprising a translucent protective film / adhesive layer 1 / polarizing element / optically anisotropic element;
The manufacturing method of the elliptically polarizing plate characterized by passing through each process of these.   15. The elliptically polarizing plate according to claim 14, wherein a rubbing treatment is performed after providing an alignment film in which a liquid crystalline composition exhibiting at least positive uniaxiality forms a nematic alignment on the polarizing element. Manufacturing method.   The method for producing an elliptically polarizing plate according to claim 13 or 14, wherein the translucent protective film is triacetyl cellulose or a cycloolefin-based polymer.   The method for producing an elliptically polarizing plate according to claim 13 or 14, wherein the translucent protective film is surface-treated.   The method for producing an elliptically polarizing plate according to claim 17, wherein the surface treatment is a saponification treatment.   The method for producing an elliptically polarizing plate according to claim 17, wherein the surface treatment is a corona discharge treatment.   The method for producing an elliptically polarizing plate according to claim 13 or 14, wherein the polarizing element is surface-treated.   The method for producing an elliptically polarizing plate according to claim 20, wherein the surface treatment is a corona discharge treatment. The liquid crystal display device which has arrange | positioned the elliptically polarizing plate in any one of Claims 1-12 in the surface of at least one side of a liquid crystal cell.

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