TW201920999A - Optical film and image display device - Google Patents

Abstract

The present invention relates to an optical film comprising a retardation layer provided with an optical function as an A-plate, and the present invention enables a simpler configuration and process and further improved quality, while ensuring sufficient viewing angle characteristics. An optical film comprising a retardation layer that provides light transmitted therethrough with an in-plane retardation, wherein: a retardation layer 7 is formed from a single layer of a polymerized product of a mixture containing a polymerizable calamitic liquid crystal monomer, and also containing a homeotropically aligning liquid crystal polymer that may be polymerizable; and a positive C-plate layer region 9 provided with the optical function of a positive C-plate, an optical interface, and a positive A-plate layer region 8 provided with the optical function of a positive A-plate are consecutively formed from one surface side of the single layer.

Description

Optical film and image display device

The present invention relates to an optical film provided with a retardation layer that functions as an A-plate, and an image display device using the optical film.

Conventionally, as for an image display device, an anti-reflection film, which is an optical film that functions as a circular polarizer, has been proposed on the panel surface (viewer-side surface) of the image display panel. The anti-reflection film can reduce the reflection of external light. . Here, this antireflection film is composed of a laminated layer of a linear polarizing plate and a 1/4 wavelength plate, and the light is directed out of the panel surface of the image display panel, and is converted into linear polarized light by the linear polarizing plate. It is converted into circularly polarized light by a quarter-wave plate. Here, although the externally polarized light is reflected on the panel surface of the image display panel, etc., the direction of rotation of the polarized surface is reversed during this reflection. As a result, the reflected light is converted into linearly polarized light in the direction blocked by the linear polarizer by the quarter-wave plate, and then blocked by the linear polarizer, so that the radiation to the outside is significantly suppressed.

With regard to this optical film, Patent Document 1 and the like propose a method of providing a 1/2 wavelength retardation layer that gives a phase difference of 1/2 wavelength to the penetrating light, and a 1 that gives a phase difference of 1/4 wavelength to the penetrating light. The / 4 wavelength retardation layer is laminated to form a 1/4 wavelength plate, and a liquid crystal material having a positive wavelength dispersion characteristic is used to make the 1/4 wavelength plate function due to the reverse dispersion characteristic of the incident light from the linear polarizer. Here, the reverse dispersion characteristic refers to a wavelength dispersion characteristic in which the phase difference in transmitted light is smaller as the wavelength is shorter.

Regarding such an optical film, Patent Document 2 proposes a 1 / 2-wavelength retardation layer and a 1 / 4-wavelength retardation layer, and regarding a laminated body of a positive C plate, it is proposed to improve the tone when viewed from an oblique direction.

However, as disclosed in Patent Document 2, when a positive C plate in which liquid crystal molecules are vertically aligned is arranged on a 1/4 wavelength plate, a desired phase difference can be given to transmitted light caused by various incident angles, thereby fully ensuring that Viewing angle characteristics can achieve anti-reflection.

However, in such a configuration, since the optical film has a multilayer structure, the number of manufacturing steps is increased. Therefore, there is a problem that productivity is reduced. In addition, due to the complexity of the manufacturing steps, there is a problem that the yield is reduced and the cost is increased. In addition, due to the complexity of the manufacturing steps, the occurrence of defects in the retardation layer increases, the yield is lowered, and the quality of optical characteristics is deteriorated.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 10-68816
[Patent Document 2] Japanese Patent Laid-Open No. 2014-224837

[Problems to be Solved by the Invention]

The present invention has been made in view of this situation. The present invention relates to an optical film having a retardation layer having an optical function as an A plate. The object of the present invention is to ensure sufficient viewing angle characteristics, and to simplify the structure and procedures. Further improve quality.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies to obtain a single layer of a mixture of a polymerizable rod-like liquid crystal monomer and a homeotropic alignment liquid crystal polymer to form a positive A plate and a positive C plate. The invention conceived the conception of an optical function layer of the optical function.

(1) An optical film, which is an optical film provided with a retardation layer that imparts an in-plane retardation to transmitted light,
The retardation layer is formed by a single layer comprising a polymer of a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer.
From one side of the single layer, the polymer has a positive C plate layer region having a positive C plate optical function due to vertical alignment, and the polymer has a positive A plate with a positive A plate optical function due to horizontal alignment. Slab area, formed continuously,
The fast axis of the phase difference layer is set as a reference axis, and the phase difference value Re becomes an extreme value in the measurement result of the phase difference value Re of the incident angle change of the phase difference layer around the reference axis. The incident angle is 20 degrees or less.

(2) The optical film according to (1), in which the boundary between the optical characteristics of the aforementioned positive C-layer region and the optical characteristics of the aforementioned positive A-layer region changes abruptly, or the optical interface defined by the region regarded as the boundary can be borrowed Defined by optical measurement.

(3) The optical film according to (1) or (2), wherein the retardation layer is formed on a linearly polarizing plate.

(4) The optical film according to (1) or (2), wherein the linearly polarizing plate sequentially forms a 1/2 wavelength retardation layer and the aforementioned retardation layer.

(5) An image display device, which is an optical film such as (1), and is disposed on a panel surface side of an audition side surface of the image display panel.

(6) An image display device, which is an optical film such as (3), and is disposed on the panel surface side of the viewer-side surface of the image display panel.

(7) An image display device, which is an optical film such as (4), and is disposed on the panel surface side of the viewer-side surface of the image display panel.

(8) A method for manufacturing an optical film, which is a method for manufacturing an optical film that forms a retardation layer that imparts an in-plane retardation to transmitted light,
The system comprises: by polymerizing a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer, an alignment layer capable of exhibiting a horizontal alignment regulating force on a liquid crystal material Or the step of extending the surface of the biaxial film to form a retardation layer that imparts an in-plane retardation to the transmitted light,
The retardation layer is a positive C plate layer region having a positive C plate optical function due to the vertical alignment of the polymer of the mixture and a positive A plate optical function of the polymer of the mixture due to the horizontal alignment. A plate layer area, a single layer formed continuously,
The fast axis of the phase difference layer is set as a reference axis, and the measurement result of the phase difference value Re of the incident angle change of the phase difference layer around the reference axis is such that the incident angle at which the phase difference value Re becomes an extreme value is 20 Degrees below.

(9) A transfer film, which is a transfer film for an optical film,
It is formed on the surface of an alignment layer or a biaxially-stretched film that can display horizontal alignment control force on a liquid crystal material to form a retardation layer that imparts an in-plane retardation to transmitted light.
The retardation layer is formed of a single layer obtained by a polymer including a polymer of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer.
From one side of the aforementioned single layer,
The polymer has a positive C plate layer region having the optical function of a positive C plate by vertical alignment, and a positive A plate layer region having the optical function of a positive A plate by horizontal alignment. ,
The fast axis of the phase difference layer is set as a reference axis, and the measurement result of the phase difference value Re of the incident angle change of the phase difference layer around the reference axis is such that the incident angle at which the phase difference value Re becomes extreme is 20 Degrees below.

(10) A method for manufacturing a transfer film, which is a method for manufacturing a transfer film for an optical film,
It includes: by polymerizing a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer, an alignment layer or a biaxially-stretched film capable of exhibiting a horizontal alignment control force on a liquid crystal material A step of forming a retardation layer that imparts in-plane retardation to the transmitted light,
The retardation layer is a positive C plate layer region having a positive C plate optical function due to the vertical alignment of the polymer of the mixture and a positive A plate optical function of the polymer of the mixture due to the horizontal alignment. A plate layer area, a single layer formed continuously,
The fast axis of the phase difference layer is set as a reference axis, and the measurement result of the phase difference value Re of the incident angle change of the phase difference layer around the reference axis is such that the incident angle at which the phase difference value Re becomes an extreme value is 20 Degrees below.

[Inventive effect]

According to the present invention, an optical film provided with a retardation layer having an optical function as a positive A-plate, in addition to ensuring sufficient viewing angle characteristics, and having a simplified structure and steps, can further improve quality.

[Form of Implementing Invention]

[First Embodiment]
[Image display device]
FIG. 1 is a sectional view of an image display device according to a first embodiment of the present invention. This image display device 1 is arranged on the panel surface side (viewer side surface) of the image display panel 2 by using an adhesive layer or the like and pasting an optical film 3 made of an anti-reflection film. As a result, the image display device 1 is configured to achieve sufficient anti-reflection by the optical film 3.
Although the image display panel 2 is an image display panel obtained by using a self-luminous element such as an organic EL element, the image display panel may be replaced with an image display panel such as a liquid crystal display panel.

[Optical film]
The optical film 3 is formed by forming a linear polarizing plate 4 and a quarter-wave plate 5. The optical film 3 is disposed at an angle of 45 degrees with respect to the transmission axis of the linear polarizing plate 4 and the slow axis of the 1/4 wavelength plate 5. Thereby, the optical film 3 functions as a circularly polarizing plate and prevents reflection of external light.

[Linear polarizer]
The linear polarizer 4 is not particularly limited as long as it includes a polarizer, and may be a polarizer having a polarizer protective film on one or both sides of the polarizer.
Examples of the polarizer include a film made of a hydrophilic polymer such as polyvinyl alcohol (PVA), which is immersed in an aqueous solution of iodine containing a dichroic pigment, and the difference between the polyvinyl alcohol and iodine formed by stretching. Or a polarizer made of a polyene (Polyene) aligner by processing a plastic film such as polyvinyl chloride.
In addition, when a dichroic dye is used as a dichroic dye instead of iodine, an azo dye, a perylene dye, a metho dye, a flower blue dye, or a pyrazolinone dye can be used as the dichroic dye. , Triphenylmethane-based dyes, quinoline-based dyes, oxazine-based dyes, anthraquinone-based dyes, anthraquinone-based dyes, and the like.

The polarizing plate protective film can protect the polarizer, and is not particularly limited as long as it has desired transparency. Examples of the material for the polarizing plate protective film include ethyl cellulose resin, cycloolefin resin, polyether resin, amorphous polyolefin, modified acrylic polymer, polystyrene, and epoxy resin. , Acrylic resin, polycarbonate resin, polyamide resin, polyimide resin, polyester resin, etc., acrylic, urethane, acrylic urethane, ring Oxygen-based, polysiloxane-based heat-curable resin, or UV-curable resin. Among them, the resin material is preferably an acetyl cellulose-based resin, a cycloolefin-based resin, or an acrylic resin. Among them, triethyl cellulose (TAC), particularly an ethyl cellulose-based resin, is preferred.

[1/4 wave plate (quarter wave plate)]
The quarter-wavelength plate 5 is a half-wavelength retardation layer 6 and a pair of half-wavelength retardation layers that impart a half-wavelength in-plane retardation to the penetrating light from a transfer film described later by a transfer method. A quarter-wavelength retardation layer 7 that imparts an in-plane retardation of a quarter-wavelength wavelength to the linearly polarizing plate 4 is sequentially pasted and arranged. The slow-axis of the 1 / 2-wavelength retardation layer 6 and the 1 / 4-wavelength retardation layer 7 are arranged at an angle of about 15 degrees and about 75 degrees with respect to the transmission axis of the linear polarizing plate 4, respectively. Therefore, the 1/4 wavelength plate 5 is configured to impart a 1/4 wavelength phase difference to the transmitted light of the linear polarizing plate 4 as a whole by a wavelength characteristic of inverse dispersion. As a result, the optical film 3 has a wide wavelength band in the visible light region, and can be configured to fully exert the anti-reflection function.
Further, in practice, when sufficient characteristics can be ensured, the half-wavelength retardation layer 6 may be omitted and only the quarter-wavelength retardation layer 7 may be transferred.
The transfer method refers to, for example, that when a desired layer is formed on a substrate, the layer is not directly formed on the substrate, but the laminated layer is formed on a release support once it is peelable. After manufacturing the transfer body (transfer film), if necessary, according to the steps, needs, etc., the layer formed on the support body will be finally laminated on the substrate (transferred substrate) on which the layer should be laminated and laminated. Thereafter, the support is removed by peeling to form a desired layer on the substrate.

[1/2 wavelength retardation layer]
The 1 / 2-wavelength retardation layer 6 is a one-layer retardation layer of a liquid crystal material produced by curing a coating layer of one layer of a polymerizable rod-like liquid crystal material. The in-plane retardation Re ( 550) is formed from 100 nm to 400 nm, preferably 220 nm to 340 nm, and more preferably 240 nm to 300 nm.
The 1 / 2-wavelength retardation layer 6 can be widely used for various polymerizable rod-shaped liquid crystal materials used for forming such a retardation layer. Specifically, various rod-shaped liquid crystal compounds having a polymerizable functional group in the molecule can be used as the liquid crystal material which is horizontally aligned by the alignment control force in the horizontal direction (in-plane direction of the alignment layer). In addition, this rod-like liquid crystal compound has refractive index anisotropy, is regularly arranged by the alignment control force of the alignment layer, and has a function of imparting desired retardation. Examples of the rod-shaped compound include a material that displays a liquid crystal phase such as a nematic phase and a smectic phase. However, compared with other liquid crystal compounds that display a liquid crystal phase, it can be arranged more easily. It is better to use a rod-shaped compound showing a nematic phase.

[1/4 wavelength retardation layer]
The 1/4 wavelength retardation layer 7 is obtained by coating a polymer of a mixture formed of a coating liquid containing a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer. A single-layer retardation layer formed by curing a single-layer coating layer, and the in-plane retardation Re (550) at a wavelength of 550 nm is 50 nm to 200 nm, preferably 110 nm to 170 nm, and more preferably It is formed from 120 nm to 150 nm.
The single layer obtained from the polymer of this mixture is a layer forming an optical interface that is not a laminated interface, but the single layer as a whole is a layer formed of a polymer of the same composition.
In addition, this single layer refers to a single layer that does not have a layered interface between layers formed by laminating layers with each other, and the like, and the entire layer is a polymer having the same composition. The single layer can be irradiated with measurement light, for example, and can be confirmed by Raman intensity distribution of reflected light. When the respective Raman absorption peaks of the polymerizable rod-like liquid crystal monomer and the polymerizable vertical alignment liquid crystal polymer are detected in the thickness direction of the layer as a whole, it can be determined that the monomer and the polymer are not separated, and the polymerized layer is mixture.

The 1 / 4-wavelength retardation layer 7 includes a positive C-plate layer region 9 having a positive C-plate optical function through vertical alignment by a polymer; and a horizontal alignment by a polymer to provide transmission light. The positive A-plate layer region 8 of the optical function of the positive A-plate having a retardation within a quarter of a quarter of a wavelength, and the positive C-plate layer region 9 becomes the orientation of the half-wavelength retardation layer 6 side, and The 1/2 wavelength retardation layer 6 is laminated.
As a result, the optical film 3 is configured such that the positive C plate layer region 9 can ensure sufficient viewing angle characteristics.

The 1/4 wavelength retardation layer 7 is an optical interface 10 between the positive C plate layer region 9 and the positive A plate layer region 8 and forms a discontinuous interface with optical characteristics and a non-laminated interface. With this optical interface 10, the positive C plate layer region, the optical interface and the positive A plate region region are formed continuously, and the positive C plate layer region 9 and the positive A plate layer region 8 are each formed with a specific thickness.
In this way, a single-layer retardation layer obtained by using a polymer of a mixture of a polymerizable rod-like liquid crystal monomer and a vertically-aligned liquid crystal polymer forms a 1 / 4-wavelength plate retardation layer 7, compared with For the laminated body of the 1/4 wavelength retardation layer formed by separately stacking the C plate layer and the positive A plate layer, the optical film 3 can simplify the structure and steps. In addition, compared with a single layer composed of a polymer of a polymerizable rod-like liquid crystal monomer and a vertically aligned polymerizable rod-like liquid crystal monomer, it is possible to sufficiently prevent the occurrence of retardation layer defects and improve optical characteristics. .
The existence of the optical interface can be confirmed, for example, by measuring the reflectance of the regular reflection of incident light at each wavelength. For example, it is confirmed that the optical interface exists because the change in reflectance (the amplitude of the pulsation) is reduced above a specific wavelength. More specifically, Fourier analysis is performed on the measurement results of the reflectance of the regular reflection of incident light at each wavelength, and the presence of the optical interface can be confirmed by confirming the peaks from the two optical interfaces (refer to the following implementation) example). The optical interface 10 is an interface between the positive C-plate layer region 9 and the positive A-plate layer region 8 having different optical characteristics. As can be seen from FIG. 4 (c) described later, the thickness of the interface due to the occurrence of reflected light is 0. However, depending on the composition of the liquid crystal material and the like, it may be considered to have a small thickness.

As described above, it is explained that the optical interface 10 is a discontinuous interface with optical characteristics between the positive C-plate layer region 9 and the positive A-plate layer region 8 and is a non-laminated interface. However, it may be misunderstood, so the optical interface 10 is described in more detail. It is called an optical interface, which is just for convenience. It does not mean that there is actually an observable interface composed of layers. The description of the non-laminated interface refers to the situation described above. In addition, as described above, this optical interface is a fictitious interface defined as an "optical-specific discontinuous interface", in other words, it is defined as the optical characteristics of the positive C-plate region and the specific sharpness of the optical of the positive A-plate region. The boundaries of change or areas that can be considered boundaries. In addition, the “region that can be regarded as a boundary” refers to a region having a small thickness (region having a thickness) that can be regarded as an optical interface when the micro interface has a small thickness due to the composition of the liquid crystal material, etc., as described above.

Further, in the positive A-plate layer region 8, the azimuth of the ½-wavelength retardation layer 6 may be arranged, and the ¼-wavelength retardation layer 7 may be disposed. In addition, instead of or in addition to the 1/4 wavelength retardation layer 7, a single layer made of a polymer of a mixture of a polymerizable rod-like liquid crystal monomer and a vertically aligned liquid crystal polymer. To form a 1 / 2-wavelength retardation layer 6, the 1 / 2-wavelength retardation layer 6 can also be formed by the structure of the positive C-plate region and the positive A-plate region.

Here, as shown in FIG. 2 (a), a mixture of a polymerizable rod-like liquid crystal monomer and a vertical alignment polymerizable rod-like liquid crystal monomer is coated on the alignment layer 22 exhibiting alignment control force in the horizontal direction. When the resulting coating liquid crystal material is hardened to form the retardation layer 11, the liquid crystal molecules 11A are aligned horizontally near the alignment layer 22 due to the alignment control force of the alignment layer 22. In addition, as the distance from the alignment layer 22 becomes smaller, the influence due to the alignment control force of the alignment layer 22 becomes smaller, and gradually, the tilt angle of the liquid crystal molecules 11A increases. In addition, near the air interface on the surface of the retardation layer 11, the liquid crystal molecules 11A are vertically aligned. This makes it possible to form a retardation layer 11 having optical functions obtained by the structure of the A-plate layer portion and the C-plate layer portion.

However, in this case, a retardation layer having optical characteristics of the structure of an A-plate and a C-plate formed by applying a liquid crystal material composed of a mixture of a polymerizable rod-like liquid crystal monomer and a vertical alignment polymerizable rod-like liquid crystal monomer is provided. 11. There is a problem that a retardation layer defect occurs and the optical characteristics are reduced.
Fig. 2 (b) is a polarizing microscope photograph of a glass plate provided with a retardation layer 11 between linearly polarized plates arranged in orthogonal polarized light and observing transmitted light. According to Fig. 2 (b), it can be confirmed that Defects in the retardation layer due to the deviation of the retardation.
In addition, in this retardation layer 11-based polymerizable rod-like liquid crystal monomer of FIG. 2 (b), a mixture in which the rod-like compounds of the following (11) and (17) are mixed at a mixing ratio of 1: 1 is used for vertical alignment. As the polymerizable rod-like liquid crystal monomer, RMM28B (manufactured by Merck) was used. In addition, a polymerizable rod-like liquid crystal monomer and a vertically-alignable polymerizable rod-like liquid crystal monomer were mixed at a mass ratio of 1: 3.75, and Megafac (F477) manufactured by DIC was added, and methyl ethyl ketone and methyl isobutyl were used. A 1: 1 ketone mixed solvent prepares a coating solution. In addition, after forming the alignment layer 22 on the glass plate by the photo-alignment layer, the coating liquid was coated with Mayer Bar # 6 because the film thickness was 2.0 μm, and the coating layer was prepared by drying. This coating layer is hardened and formed.

The occurrence of such retardation layer defects is thought to occur due to the non-uniform orientation of the alignment of the liquid crystal molecules 11A in the plane.
However, a retardation layer (1/4 wavelength retardation layer) 7 formed by a single layer of a mixture of a polymerizable rod-like liquid crystal monomer and a vertically aligned liquid crystal polymer can sufficiently prevent such retardation layer defects from occurring. .

3 (a) and 3 (b) are diagrams for explaining the phase difference layer 7 of this embodiment by comparing Figs. 2 (a) and 2 (b).
The 1 / 4-wavelength retardation layer 7 of this embodiment is compared with FIG. 2 (b), and as shown in FIG. 3 (b), a polarized microscope photo is obtained due to the overall slightly uniform brightness, thereby confirming It is possible to sufficiently prevent the occurrence of a retardation layer defect. Note that FIG. 3 (b) is a polarizing microscope photograph taken under the same conditions as in FIG. 2 (b).
In the polarizing microscope photograph of FIG. 3 (b), as the monomer for the positive A plate, a mixture in which the rod-shaped compounds of the following (11) and (17) were mixed at a mixing ratio of 1: 1 was used as the positive C plate. As the polymer, a mixture of the rod-like compounds of the following (19) and (29) at a molar ratio of 1: 1 was used. In addition, the coating liquid was prepared by mixing a monomer for positive A plate and a polymer for positive C plate at a mass ratio of 100: 1, and using a mixed solvent of 1: 1 of methyl ethyl ketone and methyl isobutyl ketone. . In addition, after forming the alignment layer 22 on the glass plate with a photo-alignment layer, the coating liquid was applied using Mayer Bar # 6 because the film thickness was 2.0 μm, and the coating layer was prepared by drying. The coating was applied by ultraviolet irradiation. The cloth layer is hardened to form a retardation layer.

As shown in FIG. 3 (a), this retardation layer 7 uses the optical interface 10 as a boundary. In the positive C plate layer region 9, the liquid crystal molecules are vertically aligned. In the positive A plate layer region 8, the liquid crystal molecules are horizontally aligned. Since the C-plate layer region 9 and the positive A-plate layer region 8 are formed to have a specific thickness, it is considered that such defects can be prevented.
The retardation layer 7 is formed of a polymer containing a mixture of a polymerizable rod-like liquid crystal monomer and a vertical alignment liquid crystal polymer, and the reason for preventing the occurrence of non-uniform alignment in the in-plane direction is still unclear. However, due to the vertically aligned liquid crystal polymer that is originally vertically aligned, the liquid crystal molecules polymerized by the polymerizable rod-like liquid crystal monomer that is originally horizontally aligned are subject to a certain form of restriction, so that the alignment of the liquid crystal molecules is appropriately controlled, and will not form as As shown in FIG. 2 (a), as the distance from the alignment layer 22 gradually increases, the tilt angle of the liquid crystal molecules gradually increases, and as shown in FIG. 4 (a), the discontinuous interface with optical characteristics The optical interface differential boundary changes from horizontal alignment to vertical alignment, and the alignment changes abruptly to form the phase difference layer 7.

FIG. 4 shows a characteristic curve of a measurement result used for confirmation of the optical interface 10, and a reflectance of regular reflection of incident light having an incident angle of 5 degrees. Fig. 4 (a) shows the measurement results of the retardation layer obtained by polymerizing only the polymer of the rod-like liquid crystal monomer. The interference of reflected light at the air interface and the substrate-side interface of the retardation layer was observed. Variation (pulsation) in reflectance due to the thickness of the retardation layer. In addition, the retardation layer is formed in a thickness of 1.6 μm as shown in FIG. 2 (a) in the same manner as the retardation layer except for the difference in the coating solution.

FIG. 4 (b) is a measurement result of the retardation layer (a single layer obtained by using a polymer containing a mixture of a polymerizable rod-like liquid crystal monomer and a vertically aligned liquid crystal monomer) according to the example of FIG. 2 (b). in. According to this FIG. 4 (b), from the short wavelength side to the long wavelength side, compared with FIG. 4 (a), a reduced state is generated, and the change (pulsation) of the reflectance is observed. The situation in 4 (a) is the same, and it is confirmed that the retardation layer is formed as a single layer.

FIG. 4 (c) is a measurement result of the retardation layer 7 (a single layer obtained by using a polymer containing a mixture of a polymerizable rod-like liquid crystal monomer and a vertically aligned liquid crystal polymer) in FIG. 3 (b). In this measurement result, the change in reflectance (amplitude of the pulsation) due to the wavelength is reduced at a wavelength of about 500 nm, thereby confirming the existence of the optical interface 10 inside the retardation layer 7.
In addition, a Fourier analysis was performed on this measurement result, and it was found that the positive C plate layer region 9 and the positive A plate layer region 8 were each formed with a thickness of 0.4 μm and 1.6 μm.

In addition, the component composition in the thickness direction of this 1/4 wavelength retardation layer 7 was irradiated with measuring light at a spot diameter of 0.8 μm, and the Raman intensity distribution due to the reflected light was observed to confirm that the polymer rod-shaped liquid crystal unit The respective Raman absorption peaks of the bulk and the homeotropically aligned liquid crystal polymer exist in the entire thickness direction of the 1/4 wavelength retardation layer 7. Therefore, it was confirmed that by forming a single layer of a polymer containing a mixture of a polymerizable rod-like liquid crystal monomer and a vertically aligned liquid crystal polymer, a positive C plate layer region 9 having a positive C plate optical function and a positive A plate were formed. The positive A plate layer region 8 of the plate's optical function is formed by a mixture.

As described above, the existence of the optical interface can be confirmed by measuring the reflectance, but there is also a concern that the existence of the optical interface cannot be determined due to the composition of the liquid crystal material and the like. At this time, even if the existence of the optical interface cannot be clearly identified, there are other methods of confirming that the positive C-plate layer region 9 and the positive A-plate layer region 8 are appropriately configured. This method will be described below.

As shown in FIG. 3, when the liquid crystal molecules 11A are aligned, and it is confirmed that the change occurs suddenly, even if the existence of the optical interface cannot be recognized, it can be confirmed that the positive C plate layer region 9 and the positive A plate layer region 8 are appropriately configured.
FIG. 7 is a diagram illustrating a method of confirming the alignment direction of the liquid crystal molecules 11A near the side of the alignment layer 22.
FIG. 8 is a diagram illustrating a method of confirming the alignment direction of the liquid crystal molecules 11A near the air interface side.
In order to investigate the alignment state of the liquid crystal molecules 11A, the cross section of the retardation layer 7 is irradiated with infrared light (polarized light IR) adjusted to a polarized state at a small point, and the reflected light is detected (measured). This is performed at the same position in various directions, and by defining a direction having a special absorption, the alignment direction of the liquid crystal molecules 11A can be confirmed. Here, as shown in FIG. 7 and FIG. 8, the retardation layer 7 may cut the surface of the retardation layer 7 in an oblique direction, and the cut surface in the oblique direction may be irradiated with polarized light IR. The cutting in the oblique direction is to increase the probability of the liquid crystal molecules 11A being irradiated with polarized IR, to prevent the liquid crystal molecules 11A from being irradiated with polarized IR, and to properly detect the reflected light. In addition, when polarized IR is used as the measurement light, not only the surface, but also data reflecting the condition at a few μm (within the 1/4 wavelength retardation layer 7) can be obtained. Therefore, in order to eliminate this effect, as shown in FIG. 7 and FIG. As shown in FIG. 8, it is confirmed that the light distribution direction is good at the front end side (acute angle side) cut diagonally.
FIG. 9 is a diagram illustrating a measurement condition in a direction of an arrow M shown in FIG. 8.
For example, when the measurement is performed in the direction of the arrow M, the polarized light IR is irradiated from the direction of the arrow M, and the measurement is performed for the entire 360-degree circle on a 10-degree scale.

FIG. 10 is a diagram showing an example of a measurement result of a phase difference value Re in which the fast axis of the retardation layer is set as a reference axis, and the reference axis is used to change the incident angle of the retardation layer.
FIG. 11 is a diagram showing another example of the measurement result of the phase difference value Re that changes the incident angle of the retardation layer by setting the fast axis of the retardation layer as a reference axis and following the reference axis.
In this embodiment, since both the positive C plate layer region 9 and the positive A plate layer region 8 are provided, as shown in FIG. 11, the downward convex characteristic is shown, but the positive A plate layer region 8 occupies a large proportion. In this case, the characteristic is convex upward as shown in FIG. 10. Therefore, regarding the ratio occupied by the positive A plate layer region 8, the characteristic curve gradually changes between the characteristic shown in FIG. 10 and the characteristic shown in FIG. 11. Therefore, in theory, there may be a case where a characteristic curve is expressed between a characteristic of upward convexity and a characteristic of downward convexity.
In addition, Examples 1 to 3 and Comparative Example 1 of FIG. 10 and Examples 1 to 3 and Comparative Example 1 of FIG. 11 are measurement data of another sample having different ratios occupied by the positive A plate layer region 8.
The measurement of the phase difference value can be measured using, for example, the KOBRA series of Oji Measurement Co., Ltd., and the RTS series of Otsuka Electronics Co., Ltd.
The phase difference layer 7 of the present embodiment has a characteristic point that cannot be obtained by the conventional configuration in the measurement result of the phase difference value.
Specifically, the fast axis of the retardation layer 7 is set as a reference axis, and along this reference axis, the phase difference value Re becomes the extreme value in the measurement result of the retardation value Re of the incident angle change of the retardation layer 7. The incident angle is 20 degrees or less, more preferably 10 degrees or less, and even more preferably, it converges to 5 degrees or less (see Examples 1 to 3 in FIGS. 10 and 11).
Therefore, when the retardation layer 7 according to this embodiment is used, it is possible to sufficiently prevent variations in optical characteristics, and to ensure good viewing angle characteristics.
This is the retardation layer 7 of the present embodiment, and because the alignment of the liquid crystal molecules 11A is not biased, an excellent effect can be obtained.

In addition, the fast axis of the retardation layer 7 is set as a reference axis, and along this reference axis, the measurement result of the phase difference value Re for a change in the incident angle of the retardation layer 7 includes the slow axis of the retardation layer 7 Measurement results of the phase difference value Re that changes the incident angle in the vertical plane of the phase difference layer.

On the other hand, in the conventional configuration shown in FIG. 2 (a), a shift in optical characteristics is apparent. The conventional structure shown in FIG. 2 (a) is generally called a "hybrid alignment liquid crystal material." The retardation layer composed of the conventional hybrid alignment liquid crystal material includes a liquid crystal material aligned in the vertical direction near the vertical alignment layer. As the distance from the vertical alignment layer gradually increases, the liquid crystal material gradually falls to the horizontal direction (lying down )characteristic. With this, the retardation layer composed of a conventional liquid crystal material in which the liquid crystal molecules are aligned at first glance is similar to the retardation layer 7 of this embodiment. However, in a retardation layer composed of a conventional hybrid alignment liquid crystal material, an angle is taken in the long axis direction of the horizontally aligned liquid crystal molecules. When the in-plane phase difference is measured, the angle at which the in-plane phase difference shows the extreme value is the incident angle. The angle that the direction of 0 degrees deviates, the characteristic of the in-plane phase difference becomes a characteristic that deviates in one direction.
This is the liquid crystal molecules 11A in the retardation layer composed of the conventional mixed alignment liquid crystal material in which the alignment of the liquid crystal molecules 11A is gradually changed, and the slowly changed area (the area where the liquid crystal molecules 11A is obliquely aligned). The phenomenon that alignment is lined up in the same direction.
For example, in a retardation layer composed of a conventional hybrid alignment liquid crystal material, the incident angle at which the retardation value takes an extreme value is 30 degrees or more, which becomes a larger angle (see the comparative examples in FIGS. 10 and 11).
Therefore, it is difficult to ensure a good viewing angle characteristic with a retardation layer composed of a conventional mixed alignment liquid crystal material.

As described above, there may be a case where a slightly flat characteristic curve is displayed between the upward convex characteristic and the downward convex characteristic. In such a case, it is difficult to define an extreme value, and a layer composed of a conventional mixed alignment liquid crystal material or a layer in the form of the retardation layer 7 of this embodiment of the present invention may not be distinguishable. In this case, set the fast axis of the retardation layer as the reference axis, and follow this reference axis to make the measurement result of the phase difference value Re of the incident angle of the retardation layer between -50 and 50 degrees. When the absolute value of the difference is 20 nm or less (a value of an extreme value of 20 degrees), the layer in the form of the retardation layer 7 of this embodiment can be determined. In addition, it is preferable that the absolute value of the difference between -50 ° and 50 ° be 10 nm or less, and more preferably 1 nm or less.

[Polymeric rod-shaped liquid crystal monomer and vertical alignment liquid crystal polymer]
Here, the polymerizable rod-like liquid crystal monomer can be widely used as a monomer for forming a retardation layer of a positive A plate with horizontal alignment. Specifically, the polymerizable rod-like liquid crystal single system refers to a liquid crystal material in which a polymerizable rod-like liquid crystal monomer is polymerized to form a polymer. Due to the horizontal alignment control force, the liquid crystal material can perform horizontally aligned monomers. As the polymerizable rod-like liquid crystal monomer, various rod-like liquid crystal compounds having a polymerizable functional group in the molecule can be used. In addition, this rod-like liquid crystal compound has refractive index anisotropy, and is regularly arranged due to the alignment control force of the alignment layer 22, and has a function of imparting desired retardation. The liquid crystal material includes, for example, a material showing a liquid crystal phase having a nematic phase and a smectic phase. However, compared with other liquid crystal compounds showing a liquid crystal phase, it can be arranged more regularly. Therefore, the liquid crystal material is based on a display nematic phase. Rod-like compounds are more preferred.
Examples of the liquid crystal compound include Japanese Patent Publication No. 2010-537954, Japanese Patent Publication No. 2010-537955, Japanese Patent Publication No. 2010-522892, Japanese Patent Publication No. 2010-522893, and Japanese Patent Publication No. 2013-509458. The compounds described in each of the published gazettes and patent publications, such as Patent No. 5892158, Patent No. 5979136, Patent No. 5994777, and Patent No. 6015655.

Specific examples of the polymerizable rod-like liquid crystal monomer include, for example, compounds represented by the following formulae (1) to (17). These compounds may be used alone or in combination for polymerization.

(g is an integer from 2 to 5)

The vertical alignment liquid crystal polymer refers to a liquid crystal material that performs vertical alignment due to the alignment control force in the vertical direction (the thickness direction of the alignment layer). The vertical alignment liquid crystal polymer may or may not have a polymerizability, but a polymer having no polymerizability is preferred. As the vertical alignment liquid crystal polymer, various polymers used for forming a phase difference layer of a positively-aligned positive C plate can be widely used.

The vertical alignment side chain type liquid crystal polymer is not particularly limited as long as it exhibits vertical alignment even without using a vertical alignment film.
In addition, the vertical alignment side chain liquid crystal polymer is, for example, a liquid crystal polymer exhibiting a liquid crystal phase having a nematic phase and a smectic phase. Among them, a liquid crystal polymer exhibiting a nematic phase is preferable in terms of easy regular arrangement. .

In addition, the alignment of the liquid crystal polymer can be determined by forming a polymer film on a glass substrate, and when the liquid crystal polymer is heat-treated at the liquid crystal temperature, the liquid crystal polymer is vertically aligned in the liquid crystal state. These substrates are used after cleaning the surface with acids, alcohols, lotions, etc., but are used without surface treatment such as silicon treatment. Due to the polymer, vertical alignment is especially carried out at the temperature near the liquid crystal phase-isotropic phase transition point, so the heat treatment operation is usually lower than 15 ° C, preferably 20 ° C, lower than the liquid crystal phase-isotropic phase transition temperature. Performed at the following temperatures.

Examples of the vertically-aligned side chain liquid crystal polymer include a polymer having a liquid crystalline constituent unit including a mesogen in a side chain.
A liquid crystal constituent unit is a constituent unit derived from a compound (hereinafter, sometimes referred to as a liquid crystal monomer) that exhibits liquid crystallinity through a spacer and a polymerizable group is bonded to a mesogenic group. In the present specification, the mesogen refers to a part having high rigidity exhibiting liquid crystallinity. For example, the mesogen has two or more ring structures, preferably three or more ring structures. The ring structures are directly bonded to each other, or A partial structure in which a ring structure is connected via 1 to 3 atoms. Since the side chain has such a mesogen, the liquid crystal constituent units can be easily aligned vertically.
The ring structure may be an aromatic ring such as benzene, naphthalene, and anthracene, or a cyclic aliphatic hydrocarbon hydrocarbon such as cyclopentyl, cyclohexyl, and the like.
When the ring structure is connected via 1 to 3 atoms, the structure of the connecting portion includes, for example, -O-, -S-, -OC (= O)-, -C (= O) -O-, -OC (= O) -O-, -NR'-C (= O)-, -C (= O) -NR'-, -OC (= O) -NR'-, -NR'-C (= O) -O-, -NR'-C (= O) -NR'-, -O-NR'-, -NR'-O-, -CH = CH-, -C≡C-, -N = N -Etc. (R 'is alkyl). Examples of the alkyl group include a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms. Among these, a linear or branched alkyl group having 1 to 3 carbon atoms is preferred. Here, the aforementioned ring structure is connected via 1 atom to 3 atoms. For example, the atoms in-"N" R '-"C" (= O)-"O"-"" are calculated in the connection part. The number of atoms in a row.
Among them, the mesogen is rod-shaped in the above-mentioned ring structure. If it is benzene, it is connected in para position, and if it is naphthalene, it is preferably rod-shaped mesogen connected in 2 and 6 positions.

In addition, since the side chain includes a constituent unit of mesogen that exhibits liquid crystallinity, from the viewpoint of vertical alignment, the end of the side chain of the constituent unit is a polar group, and therefore it is preferable to have an alkyl group or an alkoxy group. Examples of the polar group include -F, -Cl, -CN, -OCF ₃ , -OCF ₂ H, -NCO, -NCS, -NO ₂ , -NHC (= O) -R ", -C (= O)- oR ", - OH, -SH, -CHO, -SO 3 H, -NR" 2 (R " is a hydrogen atom or a carbonized hydrogen group) and the like. Examples of the alkyl group include a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms. Examples of the alkoxy group include a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms.
Liquid crystal constituent units in side-chain liquid crystal polymers, for example, HJ Neumann, M. Jarek, and G.P. Hellmann Macromolecules, 26, 2489-2495, (1993) or International Publication 2004/113469, p. 8-10 The liquid crystal constituent units derived from the conventionally known liquid crystal monomers described may be appropriately selected and used.

In addition, the constituent unit constituting the vertical alignment side chain liquid crystal polymer is preferably a constituent unit derived from a monomer having an ethylenic double bond-polymerizable group that is polymerizable with each other. Examples of such a monomer having a vinyl-containing double bond include, for example, (meth) acrylate, styrene, (meth) acrylamidine, maleimide, vinyl ether, or vinyl ester. Derivatives, among them, from the viewpoint of vertical alignment, constituent units derived from (meth) acrylate derivatives are preferred.

From the viewpoint of improving the vertical alignment of the liquid crystal constituent unit, the vertical alignment side chain liquid crystal polymer includes a liquid crystal constituent having a constituent unit that does not contain a mesogen in a side chain and a mesogen comprising a mesogen in a side chain. Units of copolymer are preferred.
At this time, in the copolymer, the content ratio of the liquid crystalline constituent unit containing mesogen in the side chain improves the vertical alignment of the liquid crystalline constituent unit and has the viewpoint of sufficient liquid crystal alignment. When the entire copolymer is 100 mol% In this case, it is preferable to set it in a range of 40 mol% to 80 mol%, and more preferably in a range of 50 mol% to 75 mol%.
In addition, from the viewpoint of increasing the vertical alignment of the liquid crystal constituent units and having sufficient liquid crystal alignment from the viewpoint that the content ratio of the constituent units containing no mesogen in the side chain is set to 20 when the entire copolymer is 100 mol%. Molar% is preferably in a range of 60 mol% or less, and more preferably in a range of 25 mol% or more and 50 mol% or less.
The content ratio of each constituent unit in the copolymer can be calculated from the integrated value obtained by ¹ H NMR measurement.

The copolymer has a constitutional unit represented by the following general formula (I) as a constitutional unit that does not contain a mesogen in a side chain, and a copolymer represented by the following general formula (I) The copolymer represented by the constitutional unit of II) is preferred. Besides, a side-chain liquid crystal polymer described in Japanese Patent No. 4174192 or a polymer having a liquid crystal group described in Japanese Patent Application Laid-Open No. 2007-217656 can also be used.

(In the general formula (I), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a group represented by-(CH ₂ ) _n -R ³ or-(C ₂ H ₄ O) _{n '} -R ⁴ . R ³ represents a methyl group which may have a substituent, an aromatic hydrocarbon group having 6 to 10 carbon atoms which may have a substituent, or -OR ⁵ , -OC (= O) R ⁵ , or -C (= O) -OR ⁵ , R ⁴ and R ⁵ each independently represent an aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 10 carbon atoms which may have a substituent, or the like Combination. N is an integer from 2 to 22, and n 'is an integer from 1 to 6.
In the general formula (II), R ¹¹ represents a hydrogen atom or a methyl group, and R ¹² represents a group represented by-(CH ₂ ) _m -or-(C ₂ H ₄ O) _{m '} -. L ₁ means direct bonding, or -O-, -S-, -OC (= O)-, -C (= O) -O-, -OC (= O) -O-, -NR ¹⁴ -C (= O)-, -C (= O) -NR ^14- , -OC (= O) -NR ^14- , -NR ¹⁴ -C (= O) -O-, -NR ¹⁴ -C (= O) ^{-NR 14 -, - O-NR} 14 -, or -NR ¹⁴ -O- represents the linking group, Ar ¹ represents 6 having an aromatic hydrocarbon group of less than 10 carbon atoms of the substituent group, having a plurality of L ¹ and Ar ¹ may be the same or different. R ¹³ represents -F, -Cl, -CN, -OCF ₃ , -OCF ₂ H, -NCO, -NCS, -NO ₂ , -NHC (= O) -R ¹⁵ , -C (= O) -OR ¹⁵ , -OH, -SH, -CHO, -SO ₃ H, -NR ¹⁵² , -R ¹⁶ , or -OR ¹⁶ , R ¹⁴ and R ¹⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R ¹⁶ represents an alkyl group having 1 to 6 carbon atoms. a is an integer of 2 or more and 4 or less, and m and m 'are each independently an integer of 2 or more and 10 or less. )

Examples of the substituent which the methyl group of R ³ may have in the general formula (I) include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, and an alkoxy group such as a methoxy group.

In the general formula (I), the aromatic ring possessed by the aromatic hydrocarbon group having 6 to 10 carbon atoms which may have a substituent in R ³ , R ^4, and R ⁵ includes, for example, a benzene ring, a naphthalene ring, and the like, among which A benzene ring is preferred.
Examples of the substituent that the aromatic hydrocarbon group may have include a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom, a cyano group, a hydroxyl group, an alkyl group, an alkoxy group, and a nitro group, and the alkyl group may include a carbon number. 1 to 10, and examples of the alkoxy group include alkoxy groups having 1 to 10 carbon atoms.

Further, in the general formula (I), the aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent in R ⁴ and R ⁵ may be any of linear, branched, and cyclic, but A straight chain is preferred. Examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, and n-decyl Straight chain alkyl, i-propyl, i-butyl, t-butyl, etc. branched alkyl, 1-propenyl, 1-butenyl, alkenyl, ethynyl, 2-propyne Alkynyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, norbornyl, adamantyl, etc. cycloalkyl, 1-cyclohexyl Cycloalkenyl and the like of alkenyl. In the case of the above-mentioned cycloalkyl, for example, n-propylcyclohexyl, n-butylcyclohexyl, etc., a cycloalkyl group in which a linear alkyl group is substituted is preferred.
Examples of the substituent which the aliphatic hydrocarbon group may have include, for example, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, an alkoxy group having 1 to 6 carbon atoms such as a methoxy group and an ethoxy group, a methyl group, Alkyl groups having 1 to 6 carbon atoms, and the like.

The combination of the aliphatic hydrocarbon group and the aromatic hydrocarbon group includes a structure in which the aliphatic hydrocarbon group is substituted with the aromatic hydrocarbon group, or a structure in which the aromatic hydrocarbon group is substituted with the aliphatic hydrocarbon group.

R ¹ in the general formula (I) is a hydrogen atom or a methyl group, and a hydrogen atom is preferred.
In R ² in the general formula (I), n is an integer of 2 or more and 22 or less, and an integer of 2 or more and 18 or less is preferred. Moreover, n 'is an integer of 1 or more and 6 or less, and 2 or more and 6 or less are preferable.

From the viewpoint of easily forming a retardation layer having excellent bending resistance and high in-plane uniformity in retardation values, the molecule of the copolymer may include-(CH) in R ² in the general formula (I). _{2) n} -, or _{- (C 2 H 4 O)} n '- indicates the different number of carbon atoms constituting the linking group of two or more units.
When two or more constituent units having different numbers of carbon atoms including a linking group are included, a combination of R2 of the constituent units represented by the general formula (I) includes, for example,
(A) A combination _of- (CH ₂ ) _n1 -R ³ _and- (CH ₂ ) _n2 -R ³ , where n1 and n2 are different numbers.
(B) Including-(C ₂ H ₄ O) _{n1 '} -R ⁴ _and- (C ₂ H ₄ O) _n2' -R ⁴ , n1 'and n2' are combinations of different numbers.
(C) A combination including-(CH ₂ ) _n1 -R ³ and (C ₂ H ₄ O) _{n2 '} -R ⁴ , n1 and n2', numbers having different numbers of carbon atoms.
(A), (B), and (C) may further include a structural unit represented by another general formula (I).
In this case, R3 having a plural number and R4 having a plural number may be independent of each other without depending on the number of n. The R3 having a plural number and R4 having a plural number may be the same or different from each other.

In the constituent units represented by the general formula (I), the combination of the values of n and n 'is not particularly limited, but from the viewpoints of bending resistance and in-plane uniformity of retardation values, it constitutes an alkylene chain or polyethylene oxide. The difference in the number of carbon atoms in the alkane chain is preferably 3 or more, and more preferably 5 or more.
Specifically, for example, when the alkylene chain has different lengths, among the two or more types of n, the largest one is nM, and the smallest one is nm. The difference between nM and nm (nM-nm) is preferably 3 or more. More preferably, it is 5 or more.
When polyethylene oxide chains have different lengths, the difference between n'M and n'm (n 'M-n'm) is preferably 2 or more, and more preferably 3 or more.

In addition, the ratio of two or more types of constituent units having different lengths of an alkylene chain or a polyethylene oxide chain among the constituent units represented by the general formula (I) is not particularly limited, but it has a carbon atom The ratio of the constituent unit of the largest number of alkylene or polyethylene oxide chains to the constituent unit of the lowest number of carbon atoms or alkylene chain or polyethylene oxide chain, in mole ratio, is preferably 1: 9-9: 1, more preferably 2: 8-8: 2.

In the general formula (I), R ³ is preferably a methyl group which may have a substituent, an aromatic hydrocarbon group having 6 to 10 carbon atoms which may have a substituent, or -OR ^5. Among these, R ³ is more preferred. Substituent methyl or -OR ⁵ .

In the general formula (I), R ⁴ and R ⁵ are an aromatic hydrocarbon group having an aliphatic hydrocarbon group having 2 to 10 carbon atoms and an aromatic hydrocarbon group having an alkoxy group having 2 to 10 carbon atoms. Or an aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent.

From the viewpoint that the temperature range of the alignment of the liquid crystal can be extended, and the precipitation of the polymerizable liquid crystal compound described later is easily suppressed, R ⁴ and R ⁵ may be substituted by straight or branched alkyl groups having 2 to 10 carbon atoms. An aromatic hydrocarbon group, or an aromatic hydrocarbon group in which a linear or branched alkoxy group having 2 to 10 carbon atoms is substituted. More specifically, straight-chain or branched alkyl or alkoxy groups having 2 to 10 carbon atoms or substituted phenyl groups, straight-chain or branched alkyl or alkane groups having 2 to 10 carbon atoms can be listed. A naphthyl group in which an oxy group is substituted, a linear or branched alkyl group having 2 to 10 carbon atoms or a biphenylene group in which an alkoxy group is substituted, and the like.
The straight-chain or branched alkyl group having 2 to 10 carbon atoms is preferably a straight-chain alkyl group having 2 to 10 carbon atoms, and more preferably 3 to 10 carbon atoms from the viewpoint of improving the aforementioned effect. The linear alkyl group is more preferably a linear alkyl group having 4 to 10 carbon atoms. The alkoxy group having 2 to 10 carbon atoms is preferably a linear alkoxy group having 2 to 10 carbon atoms, and more preferably a linear alkoxy group having 3 to 10 carbon atoms. More preferred is a linear alkoxy group having 4 to 10 carbon atoms.

Specific examples of the constituent units represented by the general formula (I) include, but are not limited to, the following formulae (18) to (28). The constituent unit represented by the general formula (II) is preferably at least one selected from the group consisting of the constituent units represented by the following formulae (29) to (31) from the viewpoint of excellent vertical alignment, and more preferably At least one selected from the group consisting of the constituent units represented by the following general formulae (29) and (30).

Here, in the constituent units represented by the general formulae (29), (30), and (31), R ¹² and R ¹³ are each the same as R ¹² and R ^{13 of the} general formula (II).

In the present disclosure, in addition to the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II), the copolymer may have a structural unit equivalent to the general formula (I) and the foregoing Any other constituent unit of the constituent unit represented by the general formula (II). Since the above-mentioned copolymer contains other constituent units, it is possible to improve, for example, solvent solubility, heat resistance, reactivity, and the like.
These other constituent units may be one type, or two or more types.

The content ratio of the other constituent units in the copolymer is when the entire copolymer is 100 mol%, preferably within a range of 0 mol% to 30 mol%, and more preferably 0 mol% or more. Within 20 mol%. When the content ratios of the other constituent units are large, the content ratios of the constituent units represented by the general formula (I) and the constituent units represented by the general formula (II) are relatively small, and vertical alignment may sometimes be obtained. Difficult situation.

The vertical alignment side chain liquid crystal polymer may have a block portion formed of a constituent unit containing no mesogen in the side chain and a block portion formed of a liquid crystal constituent unit containing a mesogen in a side chain. The block copolymer may also be a random copolymer in which the constituent units that do not contain mesogen in the side chain and the crystalline constituent units that contain mesogen in the side chain are arranged irregularly. The embodiment disclosed in this specification is preferably a random copolymer because of the viewpoint of suppressing the vertical alignment of the polymerizable rod-like liquid crystal compound described later and the viewpoint that the retardation layer is hard to crack.

The mass average molecular weight Mw of the aforementioned vertically-aligned side-chain liquid crystal polymer is not particularly limited, but it is preferably in the range of 5,000 to 60,000, more preferably in the range of 1,000 to 50,000, and more preferably 3,000 to 40,000. Within the range below. Since it is in the said range, a polymerizable liquid crystal composition is excellent in stability, and the handleability at the time of formation of a retardation layer is excellent. When the mass average molecular weight of the vertical alignment side chain liquid crystal polymer is too large, the compatibility with the polymerizable rod-like liquid crystal compound described below may be deteriorated, and a uniform film may not be easily manufactured.
The mass average molecular weight Mw is a value measured by GPC (gel permeation chromatography).

The method for producing the aforementioned vertically-aligned side-chain liquid crystal polymer is not particularly limited. For example, monomers corresponding to each constituent unit synthesized by a conventional method are mixed at a desired ratio and polymerized into a desired one. Mass average molecular weight.
In the case of a block copolymer, for example, a monomer derived from a constituent unit containing no mesogen in a side chain and a monomer derived from a mesogen constituting unit containing a mesogen in a side chain can be cited by a known polymerization method. After the polymerization, each of the obtained polymers can be linked, and one of the monomers derived from a constituent unit containing no mesogen in a side chain or the monomer derived from a mesogenic constituent unit containing a mesogen in a side chain can be linked. A method of polymerizing by a known polymerization method, adding another monomer, and then performing polymerization.
The aforementioned polymerization means may be a polymerization of a compound having a vinyl group, and generally applicable methods, for example, anionic polymerization or living radical polymerization may be used. This embodiment is preferably a method of living polymerization using Group Transfer Polymerization (GTP) as disclosed in "J. Am. Chem. Soc." 105, 5706 (1983). According to this method, it is easy to make the molecular weight, molecular weight distribution, and the like in a desired range, so that the characteristics of the obtained vertical alignment side chain liquid crystal polymer can be made uniform.

In the present specification, the structure of the vertically-aligned side-chain liquid crystal polymer can be combined with nuclear magnetic resonance spectroscopy (NMR) and thermal decomposition gas chromatography mass spectrometry (Py-GC-MS), and the matrix supports laser deionization. At least one of the MALDI-TOFMS methods is used for analysis.

The mixing ratio of the polymerizable rod-like liquid crystal monomer and the vertical alignment liquid crystal polymer is based on the mass average molecular weight Mw of the vertical alignment liquid crystal polymer, and the optimum ratio varies. For example, when the mass average molecular weight Mw of the vertical alignment liquid crystal polymer is 5000 or more and 15,000 or less, the vertical alignment liquid crystal polymer is 5.0 to 40.0 parts by mass relative to 100.0 parts by mass of the polymerizable rod-like liquid crystal monomer. 10.0 mass parts or more and 25.0 mass parts or less is more preferable. When the mass average molecular weight Mw of the vertically-aligned liquid crystal polymer exceeds 15,000 and 40,000 or less, the vertically-aligned liquid crystal polymer is preferably 0.5 to 5.0 parts by mass relative to 100 parts by mass of the polymerizable rod-like liquid crystal monomer. , More preferably 1.0 mass part to 3.0 mass parts. When the mixing amount of one of them is reduced, one of the positive A sheet region and the positive C sheet region cannot be formed, or the positive A sheet region and the positive C sheet region cannot be formed to a desired thickness and cannot be formed. Desired 1/4 wavelength retardation layer.

[Transfer film]
FIG. 5 is a cross-sectional view showing a configuration of a transfer film 20 for manufacturing the optical film 3. The transfer film 20 is formed by laminating an alignment layer 22 and a 1/4 wavelength retardation layer 7 on a substrate 21 made of a transparent film material. In this way, the 1/4 wavelength retardation layer 7 is formed on the transfer film 20 and the transfer is performed by the transfer method, so that the thickness of the optical film 3 can be reduced.

Here, as the base material 21, various transparent film materials for manufacturing a transfer film can be used, and for example, a PET (polyethylene terephthalate) film can be used.

As the alignment layer 22, various configurations capable of exhibiting a horizontal alignment control force can be used. For example, a photo-alignment layer can be used. In the example shown in FIG. 1, although only the 1 / 4-wavelength retardation layer 7 is shown and transferred by a transfer method, the alignment layer 22 may be integrally transferred.
When a member exhibiting a horizontal alignment control force such as a biaxially stretched film (for example, a PET film) is used as the substrate 21, the alignment layer 22 may be omitted.
In addition, by using the alignment layer 22 in this way, the alignment control force of the substrate 21 can be suppressed. Therefore, by adjusting the film thickness of the alignment layer 22, the position of the optical interface 10 (the position in the thickness direction of the retardation layer 7) can be variously adjusted. The optical characteristics of the 1/4 wavelength retardation layer 7 can be set to desired characteristics.

[Manufacturing method of optical film]
The manufacturing method of the optical film 3 is not specifically limited. Examples include a method for manufacturing an optical film, which includes polymerizing a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer, thereby exhibiting a horizontal alignment control force on a liquid crystal material. Forming a retardation layer on the surface of the alignment layer.
The retardation layer can also be laminated on the surface of the linear polarizing plate 4 by using a transfer film manufactured by a method for manufacturing a transfer film described later. The method of using a transfer film to laminate the film surface is to use a transfer film having a 1/2 wavelength retardation layer 6 formed on the surface of the linear polarizing plate 4 and a film having a 1/4 wavelength retardation layer 7 formed thereon. The transfer film 20 can be manufactured by sequentially stacking a 1 / 2-wavelength retardation layer 6 and a 1 / 4-wavelength retardation layer 7 on the linear polarizer 4.
The optical film 3, for example, the transfer film of the 1/2 wavelength retardation layer 6, is bonded to the linear polarizing plate 4 with an adhesive such as an ultraviolet curable resin, and the substrate of the transfer film is peeled off. The 1 / 2-wavelength retardation layer 6 is laminated on the linear polarizing plate 4 by a transfer method. Thereby, a laminated body of the linear polarizing plate 4 and the half-wavelength retardation layer 6 is formed.

Then, the 1 / 4-wavelength retardation layer 7 of the transfer film 20 is bonded to the laminated body of the linear polarizing plate 4 and the 1 / 2-wavelength retardation layer 6 with an adhesive such as an ultraviolet curable resin. Since 21 is peeled, the 1/4 wavelength retardation layer 7 is laminated by the transfer method. Then, an adhesive layer, a separator film, and the like are laminated (arranged) and cut to a desired size to produce an optical film 3. In the image display device 1, the separator film is peeled off from the optical film 3 to expose the adhesive layer, and the optical film 3 is arranged on the panel surface of the image display panel 2 by the adhesive layer.

[Manufacturing method of transfer film]
The manufacturing method of the transfer film may include a step of forming an alignment layer on the substrate; on the surface of the alignment layer, a liquid crystal material is polymerized by polymerizing a mixture of a polymerizable rod-like liquid crystal monomer and a vertically aligned liquid crystal polymer. The step of forming a retardation layer on the surface of the alignment layer with horizontal alignment control force can be demonstrated.
FIG. 6 is a flowchart showing an example of manufacturing steps of the transfer film 20. In the alignment layer forming step SP2, the transfer film 20 is formed by applying a coating liquid of the alignment layer 22 on the substrate 21, drying the substrate, and then irradiating ultraviolet rays. In addition, the alignment layer 22 is omitted, and when the 1/4 wavelength retardation layer 7 is formed by the alignment control force of the substrate 21, the alignment layer forming step SP2 is omitted.

The manufacturing steps of the transfer film 20 may also include forming a phase that imparts an in-plane phase difference to the transmitted light by polymerizing a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer. A step of a poor layer (for example, a liquid crystal material coating step SP3 and a hardening step SP4).
A coating liquid is prepared by mixing a polymerizable rod-like liquid crystal monomer and a vertically aligning liquid crystal polymer at a specific mixing ratio to prepare a coating liquid. This coating liquid is applied to the alignment layer 22 and dried (liquid crystal material). Coating step SP3).
Next, the mixture is polymerized by irradiation with ultraviolet rays without polarized light to form a 1/4 wavelength retardation layer 7 (hardening step SP4).

As described above, the optical film 3 and the image display device 1 of this embodiment exhibit the following effects.

(1) The optical film 3 of this embodiment is an optical film provided with a retardation layer 7 that imparts an in-plane retardation to the transmitted light. The retardation layer 7 includes a polymerizable rod-like liquid crystal monomer and a polymerizable rod-like liquid crystal monomer. The retardation layer formed by a single layer of a polymer of a mixture of vertically aligned liquid crystal polymers has a positive C plate layer region 9 and an optical interface with an optical function of the positive C plate due to the vertical alignment of the polymer. Due to the horizontal alignment of the polymer, the area of the positive A plate layer having the optical function of the positive A plate is continuously formed. An optical film having a retardation layer that functions as an A plate can ensure sufficient viewing angle characteristics, and The structure and steps are simplified, which can further improve the quality.

(2) In the optical film 3 of this embodiment, a retardation layer 7 is formed on the linear polarizing plate 4. The anti-reflection film of the circular polarizing plate can ensure sufficient viewing angle characteristics, and the structure and steps can be simplified. Improve quality.

(3) In addition, the optical film 3 of this embodiment is formed by sequentially forming a 1/2 wavelength retardation layer 6 and a retardation layer 7 on the linear polarizing plate 4. The anti-reflection film of the circular polarizing plate can be formed on The anti-reflection is sufficiently achieved over a wide wavelength range, and sufficient viewing angle characteristics can be ensured, and the structure and steps can be simplified to further improve the quality.

(4) The image display device of this embodiment is configured by disposing any of the optical films (1), (2), and (3) on the panel surface side of the viewer-side surface of the image display panel. An optical film made of an optical film that ensures sufficient viewing angle characteristics, has a simplified structure and steps, and can further improve quality.

(5) The manufacturing method of the optical film of this embodiment is a manufacturing method of an optical film that forms a retardation layer that imparts an in-plane retardation to transmitted light, and includes a polymerizable rod-like liquid crystal monomer and a polymerizable polymer. A step of polymerizing a mixture of vertically aligned liquid crystal polymers to form a retardation layer that imparts an in-plane retardation to transmitted light; an alignment layer that exhibits horizontal alignment control for the liquid crystal material; A single layer of a phase difference layer, a positive C plate layer region having the optical function of the positive C plate, an optical interface, and a positive A plate layer region having the optical function of the positive A plate are continuously formed.

(6) The transfer film for the optical film of this embodiment forms a surface of an alignment layer or a biaxially-stretched film that exhibits a horizontal alignment control force to the liquid crystal material, and forms a retardation layer that imparts an in-plane retardation to the transmitted light. Transfer film of 7 and retardation layer 7 is a retardation layer formed by a single layer comprising a polymer of a polymerizable rod-like liquid crystal monomer and a polymer of a polymerizable vertical alignment liquid crystal polymer. By continuously forming a positive C-plate layer region 9 that has a positive C-plate optical function due to vertical alignment of the polymer, an optical interface, and a positive A-plate optical function that has a positive A-plate optical function due to the horizontal alignment of the polymer. In the A-plate layer region, an optical film capable of ensuring sufficient viewing angle characteristics can be manufactured for a transfer film having a retardation layer that functions as an A-plate, and the structure and steps of the transfer film can be simplified to further improve the quality.

(7) The method for producing a transfer film for an optical film according to this embodiment is to form a liquid crystal material by polymerizing a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer. The step of an alignment layer or a biaxially stretched film that exhibits horizontal alignment control, and a phase difference layer that imparts an in-plane phase difference to the transmitted light can be used to continuously form a phase difference layer and have the optical properties of a positive C plate. Single layer of positive C plate layer area, optical interface, positive A plate layer area with optical function of positive A plate.

[Other embodiments]
As mentioned above, the specific structure for implementing the present invention is described in detail. However, the present invention can be modified in various ways without departing from the technical requirements of the present invention.

FIG. 12 is a diagram illustrating the retardation layer 7 when the optical interface has a small thickness.
In the example shown in FIG. 12, the optical interface 10 is confirmed to have a width in the thickness direction. With the optical interface 10 as an interface, the liquid crystal molecules are aligned vertically in the positive C plate layer region 9, and the liquid crystal molecules are horizontally aligned in the positive A plate region 8. The optical interface 10 is a state where the liquid crystal molecules are obliquely aligned between the vertical alignment and the horizontal alignment. However, unlike the case of a conventional retardation layer composed of a mixed alignment liquid crystal material as shown in FIG. 2 (a), in the retardation layer 7 of this embodiment, the alignment direction of the liquid crystal molecules 11A in the optical interface 10 is misaligned. In one direction, the liquid crystal molecules 11A are randomly mixed in all directions. In addition, although the optical interface 10 has a width in the thickness direction, the width is very small, and it is considered that at this point, the area where the optical characteristics of the positive C plate layer region and the optical characteristics of the positive A plate layer region change sharply. .

Also, in the optical interface 10 shown in FIG. 12, even if the liquid crystal molecules are in an oblique alignment state between the vertical alignment and the horizontal alignment, the alignment direction of the liquid crystal molecules 11A is not aligned in one direction, but randomly faces each direction. The liquid crystal molecules 11A are mixed. Therefore, even for the retardation layer 7 shown in FIG. 12, the measurement result of the retardation value is the result shown in each of the examples in FIG. 10 and FIG. 11, which can sufficiently prevent the deviation of the optical characteristics and ensure the Good viewing angle characteristics.
Here, as shown in the form of FIG. 12, it is assumed that the optical interface 10 has a width as described above, and description will be made. However, even with the configuration shown in FIG. 12, it is possible to define the situation of the optical interface by measuring the reflectance as described previously. In this case, for example, in FIG. 12, the optical interface 10B indicated by a one-dot chain line can be regarded as an optical interface.
In this way, the optical interface is finally identified as a place where the optical characteristics between the positive C-plate region 9 and the positive A-plate region 8 have changed drastically due to the method of identification, which may cause a certain degree of difference.

In the embodiment described above, an example in which each of the positive C plate layer region 9 and the positive A plate layer region 8 is provided in one layer will be described. Not limited to this, for example, a plurality of layers may be arranged in the positive C plate layer region 9 and the positive A plate layer region 8.
FIG. 13 is a diagram illustrating a configuration in which a plurality of layers are arranged in the positive C plate layer region 9 and the positive A plate layer region 8.
In the above-mentioned embodiment, the example in which the positive C-plate layer region 9 is disposed on the air interface side is described, but the configuration in which the positive A-sheet layer region 8 is disposed on the air interface side may be described.

In the above embodiment, the case where the optical film 3 is manufactured by the transfer method is described. However, the present invention is not limited to this. The optical film may be manufactured by laminating a retardation on a linear polarizing plate integrally with the substrate.

In the above-mentioned embodiment, the case where the present invention is used for an anti-reflection optical film has been described. However, the present invention is not limited to this, and can be widely used for forming various retardation layers having optical functions of an A plate due to horizontal alignment. Optical film.

1‧‧‧Image display device

2‧‧‧Image display panel

3‧‧‧ Optical Film

4‧‧‧Linear polarizer

5‧‧‧1 / 4 wave plate

6‧‧‧1 / 2 wavelength retardation layer

7‧‧‧1 / 4 wavelength retardation layer (phase retardation layer)

8‧‧‧A plate area

9‧‧‧ positive C plate area

10‧‧‧ Optical interface

11‧‧‧ phase difference layer

11A‧‧‧LCD molecules

20‧‧‧ transfer film

21‧‧‧ substrate

22‧‧‧Alignment layer

[FIG. 1] A diagram showing an image display device according to a first embodiment of the present invention.

[Fig. 2] An explanatory diagram for a phase difference layer using a monomer for positive A plate and a monomer for positive C plate.

[Fig. 3] An explanatory diagram of a retardation layer for the present invention.

[Fig. 4] An explanatory diagram for an optical interface in the phase difference layer of Fig. 3. [Fig.

[Fig. 5] An explanatory diagram of a transfer film.

[FIG. 6] A flowchart showing the manufacturing steps of a transfer film.

[FIG. 7] An explanatory diagram of a method for confirming the alignment direction of the liquid crystal molecules 11A near the side of the alignment layer 22. [FIG.

[FIG. 8] An explanatory diagram of a method for confirming the alignment direction of the liquid crystal molecules 11A near the air interface side.

[FIG. 9] A diagram illustrating a measurement situation from an arrow M direction shown in FIG. 7.

[Fig. 10] A diagram showing an example of a measurement result of a phase difference value Re in which the fast axis of the retardation layer is set as a reference axis, and the reference axis is used to change the incident angle of the retardation layer.

[FIG. 11] A diagram showing another example of the measurement result of the phase difference value Re that changes the incident angle of the retardation layer by setting the fast axis of the retardation layer as the reference axis and following the reference axis.

FIG. 12 is a diagram illustrating the retardation layer 7 when the optical interface has a small thickness.

13 is a diagram illustrating a configuration in which a plurality of layers of the positive C plate layer region 9 and the positive A plate layer region 8 are arranged.

Claims (10)

An optical film comprising an optical film having a retardation layer that imparts an in-plane retardation to transmitted light, The retardation layer is formed by a single layer comprising a polymer of a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer. From one side of the aforementioned single layer, The positive C plate layer region having the positive C plate optical function through the vertical alignment and the positive A plate layer region having the positive A plate optical function through the horizontal alignment in the polymer are continuously formed. The fast axis of the phase difference layer is set as a reference axis, and the phase difference value Re becomes an extreme value in the measurement result of the phase difference value Re of the incident angle change of the phase difference layer around the reference axis. The incident angle is 20 degrees or less. For example, the optical film of claim 1, wherein the boundary between the optical characteristics of the aforementioned positive C-layer region and the optical characteristics of the aforementioned positive A-layer region changes sharply or the optical interface defined by the region regarded as the boundary can be measured optically To define. The optical film according to claim 1 or claim 2, wherein the retardation layer is formed on a linear polarizer. For example, the optical film of claim 1 or claim 2, wherein the linearly polarizing plate sequentially forms a 1/2 wavelength retardation layer and the aforementioned retardation layer. An image display device is an optical film as claimed in claim 1, and is disposed on a panel surface side of an audition side surface of the image display panel. An image display device, such as the optical film of claim 3, is disposed on the panel surface side of the viewer-side surface of the image display panel. An image display device is an optical film as claimed in claim 4, and is disposed on a panel surface side of the viewer-side surface of the image display panel. An optical film manufacturing method, which is a manufacturing method of an optical film that forms a retardation layer that imparts an in-plane retardation to transmitted light, It consists of: by polymerizing a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer, an alignment layer or 2 that can exhibit a horizontal alignment control force on a liquid crystal material A step of forming a retardation layer that imparts an in-plane retardation to the surface of the axially extending film, The phase difference layer is a region of the positive C plate layer having the optical function of the positive C plate due to the vertical alignment of the polymer of the mixture, and, The single layer of the positive A plate layer area where the polymer of the foregoing mixture has the optical function of the positive A plate due to the horizontal alignment, The fast axis of the phase difference layer is set as a reference axis, and the measurement result of the phase difference value Re of the incident angle change of the phase difference layer around the reference axis is such that the incident angle at which the phase difference value Re becomes an extreme value is 20 Degrees below. A transfer film, which is a transfer film for an optical film, It is formed on the surface of an alignment layer or a biaxially-stretched film that can display horizontal alignment control force on a liquid crystal material to form a retardation layer that imparts an in-plane retardation to transmitted light. The retardation layer is formed of a single layer obtained by a polymer including a polymerizable rod-like liquid crystal monomer and a polymer of a polymerizable vertical alignment liquid crystal polymer. From one side of the aforementioned single layer, The positive C plate layer region having the optical function of the positive C plate due to the vertical alignment and the positive A plate layer region having the optical function of the positive A plate due to the horizontal alignment are continuously formed, The fast axis of the phase difference layer is set as a reference axis, and the measurement result of the phase difference value Re of the incident angle change of the phase difference layer around the reference axis is such that the incident angle at which the phase difference value Re becomes extreme is 20 Degrees below. A method for manufacturing a transfer film, which is a method for manufacturing a transfer film for an optical film, It consists of: by polymerizing a mixture of a polymerizable rod-like liquid crystal monomer and a polymerizable vertical alignment liquid crystal polymer, the alignment layer or the biaxially stretched film of the liquid crystal material can exhibit horizontal alignment control force. A step of forming a retardation layer that imparts an in-plane retardation to the transmitted light on the surface, The retardation layer is a positive C plate layer region having a positive C plate optical function due to the vertical alignment of the polymer of the mixture and a positive A plate optical function of the polymer of the mixture due to the horizontal alignment. A plate layer area, a single layer formed continuously, The fast axis of the phase difference layer is set as a reference axis, and the measurement result of the phase difference value Re of the incident angle change of the phase difference layer around the reference axis is such that the incident angle at which the phase difference value Re becomes extreme is 20 Degrees below.