JP2014123068A - Transfer body for circular polarizing plate, circular polarizing plate, image display unit, manufacturing method of transfer body for circular polarizing plate and manufacturing method of circular polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer body for a circular polarizing plate, a circular polarizing plate, an image display unit, a manufacturing method of a transfer body for a circular polarizing plate and a manufacturing method of a circular polarizing plate, capable of reducing thickness, being advantageous and having excellent flexibility, compatible to broadband wavelength and enabling manufacturing with a smaller number of process.SOLUTION: A transfer body for a circular polarizing plate includes: a quarter-wave retardation plate 6 used for lamination to a linear polarizing plate 5; and a supporting body substrate 41 for supplied the quarter-wave retardation plate 6. The supporting body substrate 41 includes an alignment surface 16 by a rubbing process on a surface thereof. The quarter-wave retardation plate 6 includes a retardation layer 17 made of a liquid crystal material having a wavelength dispersion property that a phase difference in transmitted light is smaller at a shorter wavelength side.

Description

  The present invention relates to a circularly polarizing plate formed by laminating a retardation layer made of a liquid crystal material that imparts a desired retardation to transmitted light and a linearly polarizing plate.

  In recent years, it has been proposed to form an antireflection film with a circularly polarizing plate in a flat panel display. In addition, in an optical film such as a circularly polarizing plate, a retardation layer is prepared by aligning a liquid crystal material by the alignment regulating force of the alignment layer, and a desired retardation is imparted to transmitted light by the retardation layer.

  That is, the antireflection film using a circularly polarizing plate is composed of a linearly polarizing plate and a quarter-wave retardation plate, and converts external light directed to the panel surface of the image display panel into linearly polarized light by using the linearly polarizing plate, followed by 1/4. It converts into circularly polarized light with a wavelength phase difference plate. Here, the extraneous light by the circularly polarized light is reflected by the surface of the image display panel or the like, but the rotation direction of the polarization plane is reversed during the reflection. As a result, contrary to the arrival time, this reflected light is converted from the quarter-wave retardation plate into linearly polarized light in the direction shielded by the linear polarizing plate, and then shielded by the subsequent linear polarizing plate, As a result, the emission to the outside is remarkably suppressed.

  Regarding this circularly polarizing plate, Patent Document 1 discloses a method of forming a circularly polarizing plate with reverse dispersion characteristics by combining a half-wave plate and a quarter-wave plate to form a quarter-wave retardation plate. Has been proposed. In the case of this method, a circularly polarizing plate can be formed with a reverse dispersion characteristic using a liquid crystal material with a positive dispersion characteristic, thereby preventing reflection of extraneous light efficiently in a wide wavelength band. Here, the reverse dispersion characteristic means a wavelength dispersion characteristic in which the phase difference in transmitted light is smaller toward the shorter wavelength side.

  In recent years, materials having reverse dispersion characteristics have been proposed as liquid crystal materials applicable to retardation layers such as circularly polarizing plates (Patent Documents 2 and 3). According to the liquid crystal material having such a reverse dispersion characteristic, instead of forming a quarter-wave retardation plate by combining two half-wave plates and a quarter-wave plate to form a quarter-wave retardation plate by two layers. The wavelength retardation plate can be constituted by a single layer to ensure reverse dispersion characteristics.

  By the way, this kind of circularly polarizing plate is desired to be manufactured at a low cost with a smaller number of steps because it can reduce the overall thickness so as not to impair the flexibility of a display, etc. It is rare.

JP-A-10-68816 U.S. Pat. No. 8,119,026 JP 2009-179563 A

  The present invention has been made in view of such a situation. The transfer for a circularly polarizing plate, which can be reduced in thickness, has excellent flexibility, supports a wide wavelength range, and can be manufactured with a small number of steps. It is an object to provide a method for producing a circularly polarizing plate, a circularly polarizing plate, an image display device, a circularly polarizing plate transfer body, and a circularly polarizing plate.

  The present inventor has intensively researched to solve the above-mentioned problems, and a liquid crystal material having a reverse dispersion characteristic on the surface of a support substrate, not an alignment film having a specific composition, but an alignment surface by rubbing treatment. The idea of forming a circularly polarizing plate by transferring the retardation layer alone to the polarizing plate was achieved, and the present invention was conceived.

    Specifically, the present invention provides the following.

(1) In a transfer body for a circularly polarizing plate in which a transfer layer is laminated on a linearly polarizing plate, and the circularly polarizing plate is constituted by the linearly polarizing plate and the transfer layer,
The transfer layer;
A support substrate that supports the transfer layer,
The support substrate is
Has an alignment surface on the surface by rubbing treatment,
The transfer layer is
A transfer body for a circularly polarizing plate, which is a retardation layer formed of a liquid crystal material having a wavelength dispersion characteristic such that the retardation in transmitted light is smaller toward the shorter wavelength side.
According to (1), a single-layer retardation layer can be formed of a liquid crystal material having so-called reverse dispersion characteristics. For this reason, the transfer body for circularly-polarizing plates which is thin and excellent in flexibility can be provided. In addition, since the retardation layer is a single layer, it is possible to provide a transfer body for a circularly polarizing plate with a small number of steps and low manufacturing costs. Also, application of a transfer method can reduce the thickness and improve flexibility.
(2) The circularly polarizing plate, wherein the transfer layer of the circularly polarizing plate transfer body according to (1) is laminated on the linearly polarizing plate.
According to (2), since the single retardation layer is transferred by the liquid crystal material having so-called reverse dispersion characteristics, it is possible to provide a circularly polarizing plate having a small thickness and excellent flexibility. In addition, since the retardation layer is a single layer, it is possible to provide a circularly polarizing plate with a small number of steps and low manufacturing costs. Also, application of a transfer method can reduce the thickness and improve flexibility.
(3) An image display device, wherein the circularly polarizing plate according to (2) is disposed on the front side surface of the image display panel.
According to (3), the image display apparatus provided with the circularly-polarizing plate which is thin and excellent in flexibility can be provided.

(4) In the method for producing a circularly polarizing plate transfer body in which a transfer layer is laminated on a linearly polarizing plate, and a circularly polarizing plate is constituted by the linearly polarizing plate and the transfer layer,
An alignment surface forming step of rubbing the surface of the support substrate and forming an alignment surface on the surface;
A step of applying a liquid crystal material having a wavelength dispersion characteristic such that the phase difference in transmitted light is smaller on the alignment surface as the wavelength is shorter, and aligning the liquid crystal material by the alignment regulating force of the alignment surface;
Irradiating the aligned liquid crystal material with high energy rays, and curing the liquid crystal material so that the alignment state of the liquid crystal material is preserved to form the transfer layer by a retardation layer. The manufacturing method of the transfer body for circularly-polarizing plates.
According to (4), since the retardation layer can be formed as a single layer, it is possible to provide a method for producing a circularly polarizing plate transfer body with a small number of steps and low production costs.

(5) In the manufacturing method of the circularly-polarizing plate which laminated | stacked the linearly-polarizing plate and the phase difference layer,
An alignment surface forming step of rubbing the surface of the support substrate and forming an alignment surface on the surface;
A step of applying a liquid crystal material having a wavelength dispersion characteristic such that the phase difference in transmitted light is smaller on the alignment surface as the wavelength is shorter, and aligning the liquid crystal material by the alignment regulating force of the alignment surface;
Irradiating the aligned liquid crystal material with high energy rays, curing the liquid crystal material so that the alignment state of the liquid crystal material is preserved, and forming a retardation layer;
Integrating the retardation layer and the linearly polarizing plate;
And a step of peeling the support substrate from the retardation layer. A method for producing a circularly polarizing plate, comprising:
According to (5), since the retardation layer can be formed as a single layer, it is possible to provide a method for manufacturing a circularly polarizing plate with a small number of steps and low manufacturing costs.

  According to the above-described invention, a circularly polarizing plate transfer body, a circularly polarizing plate, an image display device, and a circularly polarizing plate transfer body that can be made thin, have excellent flexibility, and can be manufactured with a small number of steps. The manufacturing method of this and the manufacturing method of a circularly-polarizing plate can be provided.

It is a figure which shows the image display apparatus and circularly-polarizing plate which concern on one Embodiment of this invention. It is the figure which showed the transfer body for circularly-polarizing plates of one Embodiment of this invention. It is a figure for showing the manufacturing process of the circularly-polarizing plate shown in FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[Image display device, circularly polarizing plate]
FIG. 1 is a diagram illustrating an image display device and a circularly polarizing plate according to the present embodiment. In the image display device 1, a circularly polarizing plate 3 is disposed on the front side surface (viewer side surface) of the image display panel 2. The image display panel 2 is a flexible organic EL panel having a sheet shape, for example, and displays a desired color image.

  The circularly polarizing plate 3 functions as an antireflection film that suppresses reflection of extraneous light arriving at the image display panel 2. The circularly polarizing plate 3 is configured by laminating a linearly polarizing plate 5 and a ¼ wavelength phase difference plate 6. The circularly polarizing plate 3 is peeled off a separator film (not shown) to expose the pressure-sensitive adhesive layer 4 made of a pressure-sensitive adhesive, and is then attached and held on the front side surface of the image display panel 2 by the pressure-sensitive adhesive layer 4. The linear polarizing plate 5 and the quarter-wave retardation plate 6 are integrated with each other through the adhesive layer 7. As a result, the circularly polarizing plate 3 converts extraneous light traveling toward the panel surface of the image display panel 2 into linearly polarized light by the linearly polarizing plate 5 and then converts it into circularly polarized light by the ¼ wavelength phase difference plate 6. As a result, the reflected light that is reflected by the surface of the image display panel 2 and the rotation direction of the polarization plane is reversed is shielded from the quarter-wave retardation plate 6 by the linear polarizing plate 5, contrary to the arrival time. After being converted to linearly polarized light in a certain direction, the subsequent linearly polarizing plate 5 shields the light, thereby remarkably suppressing the emission of reflected light to the outside.

  The pressure-sensitive adhesive layer 4 and the pressure-sensitive adhesive layer 7 may be an adhesive layer made of an adhesive. Incidentally, for example, an acrylic pressure-sensitive adhesive can be applied to the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer. As the adhesive, a photo-curing adhesive such as an ultraviolet curable adhesive, a thermosetting adhesive, or the like can be applied. The pressure-sensitive adhesive and the adhesive need only be those that do not significantly deteriorate the optical properties, and are not limited to these, and various materials can be applied.

  The linear polarizing plate 5 is formed by sequentially arranging the optical functional layer 11 and the adhesive layer 7 after the lower surface side of the substrate 10 made of a transparent film such as TAC (triacetylcellulose) is saponified, It is integrated with the four-wavelength phase difference plate 6. A transparent base material layer may be provided between the optical function layer 11 and the adhesive layer 7. Here, the optical functional layer 11 is a part that bears an optical function as a linear polarizing plate, and is produced, for example, by adsorbing and orienting iodine compound molecules on a film material of polyvinyl alcohol (PVA). In this embodiment, PVA (polyvinyl alcohol) glue is applied to the adhesive layer 7.

  The quarter-wave retardation plate 6 has a retardation layer 17 made of a cured liquid crystal material layer, and the retardation layer 17 gives a phase difference corresponding to a quarter wavelength to transmitted light. In this embodiment, this liquid crystal material is a liquid crystal material having reverse dispersion characteristics, whereby the quarter-wave retardation plate 6 is formed of a single layer to ensure reverse dispersion characteristics. The retardation layer 17 is prepared by being cured in a state in which the liquid crystal material is aligned by the alignment regulating force of the alignment surface due to the rubbing trace formed on the support substrate 21 described later, and thereby a desired retardation is transmitted to the transmitted light. Is granted.

  For the circularly polarizing plate 3, the transfer method is applied to the integration of the linearly polarizing plate 5 and the quarter-wave retardation plate 6 by the adhesive layer 7.

  Here, in the transfer method, for example, when a desired layer is formed on a base material, the layer is not directly formed on the base material, but can be peeled once on a releasable support. After forming the transfer body by laminating the layers, the layer formed on the support is finally placed on the base material (transfer base material) on which the layer is to be laminated according to the process, demand, etc. In this method, a desired layer is formed on the substrate by bonding and laminating, and then peeling and removing the support.

  In this embodiment, the quarter-wave retardation plate 6 is laminated on the linear polarizing plate 5 by the transfer method, so that the substrate to be transferred is the linear polarizing plate 5, and the layer (transfer layer) used for transfer is , 1/4 wavelength phase difference plate 6.

[Transfer for circularly polarizing plate]
FIG. 2 is a view showing a circularly polarizing plate transfer body (hereinafter referred to as “transfer film”) 40 which is a transfer body to be used for transfer by this transfer method. The transfer film 40 includes a support base material 41 made of a transparent film material such as PET (polyethylene terephthalate), and the support base material 41 is provided with an alignment surface 16 and a retardation layer 17. Here, the alignment surface 16 is provided for aligning the liquid crystal material applied to the retardation layer 17. As will be described later, the alignment film 16 is formed by rubbing the surface of the support base material 41 and forming a rubbing trace formed on the surface. Although the rubbing trace is generally referred to as a line-shaped uneven shape extending in one direction, even when such a line-shaped uneven shape cannot be seen, the liquid crystal described later is practically sufficient. The material can be oriented. Subsequently, the adhesive film 7 and the separator film 43 are provided on the transfer film 40 thus configured.

  In this embodiment, although the retardation layer 17 that is a transfer layer is provided directly on the support base material 41, the support is not sufficiently peelable between the support base material 41 and the transfer layer. A release layer that promotes peeling may be provided on the substrate 41.

  For the release layer, a material having relatively high adhesion to the support substrate 41 (low peelability) and low adhesion to the transfer layer (high peelability) can be applied. More specifically, the release layer is, for example, a silicon resin (organosilicon polymer compound), a fluorine resin, a melamine resin, an epoxy resin, or other appropriate resin (acrylic resin, cellulose resin, polyester). A mixture with a resin etc. can be applied.

[Method of manufacturing circularly polarizing plate]
3A to 3E are diagrams for illustrating a manufacturing process of the circularly polarizing plate 3 illustrated in FIG. In this manufacturing process, the surface 41a of the support substrate 41 is rubbed, and the orientation surface 16 (FIG. 3A) is produced on the surface 41a of the support substrate 41. Subsequently, the material layer of the retardation layer 17 is produced by applying the liquid crystal material 17a by a die coater or the like (FIG. 3B), and the liquid crystal material according to the retardation layer 17 is aligned by the alignment regulating force of the alignment surface 16 Thus, the retardation layer 17 is produced by being cured by irradiation with ultraviolet rays (FIG. 3C). Then, after the adhesive layer 7 and the separator film 43 are provided to obtain the circularly polarizing plate transfer body 40, the separator film 43 is peeled off and integrated with the linearly polarizing plate 5 (FIG. 3D). The body base material 41 is peeled off (FIG. 3E). The circularly polarizing plate 2 is then provided with an adhesive layer 4 and a separator film.

(Support base material)
As a material of the support substrate 41, a rubbing treatment is possible, and a PET film is preferable from the viewpoints of liquid crystal orientation, transferability, mechanical strength during production, solvent resistance, and the like. However, the support substrate 41 is not limited to a PET film. As the support base material 41, for example, cellulose acylate, cycloolefin polymer, acrylate polymer, or the like can be applied. Furthermore, as the support base material 41, the above members may be mixed with a plurality of other members and used as the main body. Here, “mainly” means a component having the highest content ratio among the constituent components of the base material.

(Rubbing process)
Here, various methods can be widely applied to the rubbing treatment used to create the alignment surface 16. Specifically, for example, there is a method in which a rubbing roll is brought into contact with a long transparent film in the conveyance process at an arbitrary angle, and the rubbing roll is rotated to rub the film surface. In this case, it is also possible to use a rubbing belt instead of the rubbing roll. The rubbing roll is a roll material in which a fiber rubbing material is wound around the surface. The rubbing material for the fiber is not particularly limited, and a flocking cloth such as cotton, rayon, polyester, acetate, nylon or the like can be used.

  In this embodiment, a PET film (Toyobo, E5100) having a thickness of 50 μm is applied to the support substrate 41, and a rubbing roll (φ150 mm) in which nylon fibers are wound as a rubbing material is used. The rubbing process was performed by placing and rotating the rubbing roll with the rotation axis inclined at a 45 ° angle with respect to the transport direction. In addition, the conveyance speed of PET film was 10 m / min, and the rotational speed of the rubbing roll was 1000 rpm. The pushing amount of the rubbing roll against the PET film was 3 mm.

(Retardation layer)
In the step of producing the retardation layer 17, the application of the liquid crystal material 17 a is not limited to the configuration of application by a die coater, and various application methods can be widely applied. Note that coating by a die coater can be said to be a coating method suitable for this embodiment because the coating thickness can be easily controlled.

The liquid crystal material 17a applied to the retardation layer 17 is a liquid crystal material (manufactured by Merck) having reverse dispersion characteristics diluted to a solid content of 30% (cyclohexanone: MIBK = 7: 3). Irradiation of the ultraviolet rays to the aligned liquid crystal material 17a is performed at a fusion UV, an H bulb 177 mJ / cm ² , and a substrate conveyance speed of 10 m / min.

  In the present embodiment, an ultraviolet curable liquid crystal that is cured by ultraviolet rays is used as the liquid crystal material 17a. However, the present embodiment is not limited to such a configuration, and the liquid crystal material 17a is irradiated with other high energy rays. A liquid crystal material that cures may be used. As other high energy rays, in addition to ultraviolet rays, for example, energy rays including ionized particles such as electron beams, X-rays, and the like can be considered.

In the retardation layer 17, it is preferable that the relationship between the retardation (R ₄₅₀ ) at a wavelength of ₄₅₀ nm and the retardation (R ₅₅₀ ) at a wavelength of 550 nm is R ₄₅₀ / R ₅₅₀ <1. In general, the liquid crystal compound often has positive wavelength dispersion or no wavelength dispersion. In order to develop the inverse dispersion characteristic, it is necessary to arrange at least two types of absorption wavelengths and the direction of the transition moment well. Since the retardation R is a value obtained by subtracting the refractive index of ordinary light from the refractive index of extraordinary light, the wavelength dispersibility of ordinary light is lower than that of extraordinary light. R slope when the left side is the short wavelength side). The wavelength dispersion of the refractive index is closely related to the absorption of the substance, as represented by the Lorentz-Lorenz equation. Therefore, in order to make the wavelength dispersion of ordinary light more downward, the normal light direction If the absorption wavelength of can be made longer, a molecule satisfying the inverse dispersion characteristic can be designed.

The direction of ordinary light is, for example, the width direction of molecules in a rod-like liquid crystal, and it is very difficult to lengthen the absorption transition wavelength in the width direction of such molecules. In order to lengthen the absorption transition, it is usually possible to widen the pi-conjugated system. However, if such a method is used, the width of the molecule is widened, and the liquid crystallinity is It will disappear. In order to prevent such a decrease in liquid crystallinity, William
N. It is possible to use a skeleton in which two rod-like liquid crystals reported by Thurms et al. (Liquid Crystals, 25, 149, 1998) are connected in the lateral direction.

  Examples of such a liquid crystal compound having reverse dispersion include liquid crystal compounds described in JP-T-2010-528992 and JP-A-2006-243470.

  However, liquid crystal compounds having reverse dispersion as described above are difficult to align uniformly due to their unique steric structure, and there has been no suitable alignment layer for aligning this type of liquid crystal compound. As a result, in the present invention, by subjecting the transparent film to be the support substrate to surface rubbing treatment, the transparent film itself can be used as the alignment layer material layer to achieve both reverse dispersion and orientation.

[Experimental Example 1]
Here, an experiment was conducted to verify whether or not a retardation layer can be formed by rubbing the support substrate surface to obtain an alignment surface, and applying and curing a liquid crystal material having reverse dispersion characteristics. Hereinafter, the conditions of the verification experiment will be described.

In this experiment, a PET original fabric (E5100, manufactured by Toyobo Co., Ltd.) was rubbed 10 times and 100 times, respectively, under a load of 0 g using a RUBING TESTER. Then, as a liquid crystal material having reverse dispersion characteristics, Miyabar # 5 (manufactured by Merck & Co., Inc.), solid content 30% (cyclohexanone: MIBK = 7: 3)) was applied to the rubbed PET original surface, and heated at 65 ° C. for 3 minutes Dried. Furthermore, ultraviolet irradiation was performed under the condition of an H bulb and N ₂ .

  As a result of the above experiment, it was confirmed that the liquid crystal material after heat drying and ultraviolet irradiation was aligned. In addition, when the reverse dispersion characteristic liquid crystal layer after ultraviolet irradiation was transferred to a glass substrate using an adhesive, good transferability (practical use) was achieved without providing a release layer at both 10 and 100 times of rubbing. To the extent that it can withstand the damage). Even when the number of times of rubbing is 10, good characteristics can be obtained as in the case of 100 times, so that the rubbing process can be simplified.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Image display panel 3 Circular polarizing plate 4, 7 Adhesive layer 5 Linear polarizing plate 6 1/4 wavelength phase difference plate 10 Base material 11 Optical function layer 16 Orientation surface 17 Phase difference layer 17a Liquid crystal material 40 Transfer film 41 Support base material 43 Separator film

Claims (5)

In a circularly polarizing plate transfer body in which a transfer layer is laminated on a linearly polarizing plate and a circularly polarizing plate is constituted by the linearly polarizing plate and the transfer layer,
The transfer layer;
A support substrate that supports the transfer layer,
The support substrate is
Has an alignment surface on the surface by rubbing treatment,
The transfer layer is
A transfer body for a circularly polarizing plate, which is a retardation layer formed of a liquid crystal material having a wavelength dispersion characteristic such that the retardation in transmitted light is smaller toward the shorter wavelength side. The circularly polarizing plate, wherein the transfer layer of the circularly polarizing plate transfer body according to claim 1 is laminated on the linearly polarizing plate. An image display device comprising: the circularly polarizing plate according to claim 2 disposed on a front side surface of an image display panel. In the method for producing a circularly polarizing plate transfer body in which a transfer layer is laminated on a linearly polarizing plate, and a circularly polarizing plate is constituted by the linearly polarizing plate and the transfer layer,
An alignment surface forming step of rubbing the surface of the support substrate and forming an alignment surface on the surface;
A step of applying a liquid crystal material having a wavelength dispersion characteristic such that the phase difference in transmitted light is smaller on the alignment surface as the wavelength is shorter, and aligning the liquid crystal material by the alignment regulating force of the alignment surface;
Irradiating the aligned liquid crystal material with high energy rays, and curing the liquid crystal material so that the alignment state of the liquid crystal material is preserved to form the transfer layer by a retardation layer. The manufacturing method of the transfer body for circularly-polarizing plates. In the method of manufacturing a circularly polarizing plate in which a linearly polarizing plate and a retardation layer are laminated,
An alignment surface forming step of rubbing the surface of the support substrate and forming an alignment surface on the surface;
A step of applying a liquid crystal material having a wavelength dispersion characteristic such that the phase difference in transmitted light is smaller on the alignment surface as the wavelength is shorter, and aligning the liquid crystal material by the alignment regulating force of the alignment surface;
Irradiating the aligned liquid crystal material with high energy rays, curing the liquid crystal material so that the alignment state of the liquid crystal material is preserved, and forming a retardation layer;
Integrating the retardation layer and the linearly polarizing plate;
And a step of peeling the support substrate from the retardation layer. A method for producing a circularly polarizing plate, comprising:

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