JP2017138401A - Optical film and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture an optical film of a large area by using a material of high versatility, relating to the optical film equipped with a 1/4 wavelength plate formed by stacking a 1/4 wavelength phase difference layer and a 1/2 wavelength phase difference layer.SOLUTION: Relating to an optical film 3 equipped with a laminate of a linear polarizing plate 5 and a 1/4 wavelength plate 6, at the 1/4 wavelength plate 6, a 1/2 wavelength phase difference layer 6B which provides a transmission light with a phase difference of 1/2 wavelength and a 1/4 wavelength phase difference layer 6A which provides the transmission light with a phase difference of 1/4 wavelength are sequentially provided from a side of the linear polarizing plate 5. When viewed from a side of the linear polarizing plate 5, relative to an absorbing axis of the linear polarizing plate 5, a slow axis of the 1/2 wavelength phase difference layer 6B forms an angle of 20° to 25°, or, forms an angle of 65° to 70°, and, a slow axis of the 1/4 wavelength phase difference layer 6A forms an angle of -5° to 5°, or, forms an angle of 85° to 95°.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical film or the like for preventing reflection by the function of a circularly polarizing plate.

  Conventionally, an antireflection film, which is an optical film that functions as a circularly polarizing plate and prevents reflection, is disposed on the panel surface (viewer side surface) of an image display panel, and the reflection of external light is reduced by this antireflection film. Has been proposed. This antireflection film is composed of a laminate of a linearly polarizing plate and a quarter wavelength plate, converts external light directed to the panel surface of the image display panel into linearly polarized light by the linearly polarizing plate, and then continues with a circle by the quarter wavelength plate. Convert to polarized light. Although the extraneous light by the circularly polarized light is reflected on the surface of the image display panel or the like, the rotation direction of the polarization plane is reversed during the reflection. As a result, this reflected light is converted into linearly polarized light in the direction shielded by the linear polarizing plate by the quarter wavelength plate, contrary to the arrival time, and then shielded by the subsequent linear polarizing plate. Outgoing emission is significantly suppressed.

  Regarding this antireflection film, Patent Documents 1 and 2, etc., provide a half-wave retardation layer that imparts a phase difference of ½ wavelength to transmitted light, and a phase difference of a quarter wavelength to transmitted light. By forming a quarter wavelength plate by laminating a quarter wavelength retardation layer, a quarter wavelength plate is formed with respect to incident light from a linearly polarizing plate using a liquid crystal material having positive dispersion characteristics. A method of functioning with inverse dispersion characteristics is disclosed. Here, the reverse dispersion wavelength characteristic is a characteristic in which the phase difference given to the transmitted light increases as the wavelength of the transmitted light becomes longer. More specifically, the retardation at the wavelength of 450 nm (Re450) and the retardation at the wavelength of 550 nm (respectively) The relationship with Re550) is a characteristic of Re450 <Re550.

  By the way, it is desired that such an antireflection film can be easily produced in a large area using a highly versatile material.

JP-A-10-68816 JP 2000-284126 A

  The present invention has been proposed in view of such circumstances, and relates to an optical film including a quarter-wave plate formed by stacking a quarter-wave retardation layer and a half-wave retardation layer. An object of the present invention is to make it possible to easily produce a large-area material using a high material.

  The present inventor has intensively studied to solve the above-described problems, and the quarter-wave phase difference layer is set so that the slow axis direction is parallel or orthogonal to the absorption axis of the linearly polarizing plate. In addition, the present invention has been completed by the idea that the half-wave retardation layer is arranged so that the slow axis direction forms an angle of approximately 22.5 degrees or 67.5 degrees.

  Specifically, the present invention provides the following.

(1) In an optical film provided with a laminate of a linearly polarizing plate and a quarter-wave plate,
The quarter-wave plate is
From the linear polarizing plate side,
A half-wave retardation layer that imparts a half-wave phase difference to transmitted light;
A quarter-wave retardation layer for sequentially imparting a quarter-wave phase difference to the transmitted light,
Seen from the linear polarizing plate side, with respect to the absorption axis of the linear polarizing plate,
The slow axis of the ½ wavelength retardation layer forms an angle of 20 degrees or more and 25 degrees or less, or forms an angle of 65 degrees or more and 70 degrees or less,
An optical film in which a slow axis of the quarter-wave retardation layer forms an angle of −5 degrees to 5 degrees, or an angle of 85 degrees to 95 degrees.

  According to (1), the slow axis direction of the quarter-wave retardation layer can be made substantially coincident with or orthogonal to the absorption axis direction of the linearly polarizing plate, and the length wound on the roll It is possible to simplify the process of producing an optical film by laminating a quarter-wave retardation layer having a similar long film shape to a linear polarizing plate having a long shape, thereby enabling a large area optical A film can be easily produced. In this case, for example, a quarter-wave retardation layer can be formed by applying a highly versatile material such as a stretched transparent film material. As a result, an optical film can be formed using a highly versatile material. Can be produced.

(2) In (1),
An optical film in which the half-wave retardation layer is formed of a polymerizable liquid crystal material.

  According to (2), the angle where the slow axis of the ½ wavelength retardation layer is 20 degrees or more and 25 degrees or less with respect to the absorption axis of the linearly polarizing plate according to the requirement of (1) by a more specific configuration. Or an angle of 65 degrees to 70 degrees.

(3) In (1) or (2),
The difference value (Re4 (450) obtained by subtracting the wavelength dispersion Re2 (450) / Re2 (550) of the 1/2 wavelength retardation layer from the wavelength dispersion Re4 (450) / Re4 (550) of the 1/4 wavelength retardation layer. ) / Re4 (550) -Re2 (450) / Re2 (550)) is from -0.05 to 0.25.
Where Re (λ) is the in-plane phase difference at the wavelength λ.

  According to (3), the chromatic dispersion characteristics of the ¼ wavelength phase difference layer and the ½ wavelength phase difference layer can be balanced, and the color of the panel surface when arranged on the image display panel. The taste can be improved.

(4) In any one of (1), (2) and (3),
The 1/2 wavelength retardation layer is
An optical film having a wavelength dispersion Re2 (450) / Re2 (550) of 1.00 or more and 1.15 or less.

(5) In any one of (1), (2), (3) and (4),
The quarter-wave retardation layer is
Stretched film material,
An optical film having a wavelength dispersion Re4 (450) / Re4 (550) of 1.04 to 1.25.

  According to (4) or (5), the color of the panel surface can be improved by arranging the image display panel with a more specific configuration.

(6) In any one of (1), (2), (3), (4), (5),
The 1/2 wavelength retardation layer is
In-plane retardation Re4 (550) at a wavelength of 550 nm is 220 nm or more and 270 nm or less,
The quarter-wave retardation layer is
An optical film having an in-plane retardation Re4 (550) at a wavelength of 550 nm of from 100 nm to 160 nm.

  According to (6), the 1/4 wavelength phase difference layer and the 1/2 wavelength phase difference layer can be configured with a more specific configuration.

  (7) An image display device in which the optical film according to any one of (1), (2), (3), (4), (5), and (6) is disposed on a panel surface of an image display panel.

(8) In (7),
The image display panel is an image display panel using an organic EL element,
An image display device in which reflectances Rf (450) and Rf (700) at wavelengths of 450 nm and 700 nm satisfy Rf (450)> Rf (700).

  According to (8), the image display panel surface can be bluish black and the quality of the image display panel can be improved.

  According to the present invention, for an optical film provided with a quarter-wave plate by laminating a quarter-wave retardation layer and a half-wave retardation layer, a large area can be easily obtained using a highly versatile material. Things can be made.

It is a figure which shows the image display apparatus which concerns on 1st Embodiment of this invention. It is a figure where it uses for description of the optical film which concerns on the image display apparatus of FIG. It is a flowchart which shows the manufacturing process of the optical film of FIG. It is a graph which shows an Example and a comparative example.

[First Embodiment]
FIG. 1 is a diagram showing an image display apparatus according to the first embodiment of the present invention. In this image display device 1, an antireflection film 3, which is an optical film for preventing reflection by the function of a circularly polarizing plate, is disposed on the panel surface (viewer side surface) of the image display panel 2. Here, the image display panel 2 is an image display panel (organic EL panel) using, for example, an organic EL element, and displays a desired color image. The image display panel 2 is not limited to the organic EL panel, and various image display panels such as a liquid crystal display panel can be widely applied.

  The antireflection film 3 is adhered and held on the panel surface of the image display panel 2 by an adhesive layer 4 made of PSA (Pressure Sensitive Adhesive) adhesive. The antireflection film 3 is formed by laminating and integrating a linear polarizing plate 5 and a quarter wavelength plate 6 with an adhesive layer 8 made of a PSA adhesive. In addition, it may replace with the adhesive layer by a PSA adhesive, and you may arrange | position the anti-reflective film 3 with another adhesive and an adhesive agent, and also make it laminate | stack the linearly-polarizing plate 5 and the quarter wavelength plate 6. FIG. Good. Examples of such other pressure-sensitive adhesives and adhesives include ultraviolet curable resins and thermosetting resins.

  With the arrangement of the antireflection film 3, the image display device 1 is set so that the regular reflectances Rf (450) and Rf (700) at wavelengths of 450 nm and 700 nm satisfy Rf (450)> Rf (700). As a result, anti-reflection in a wide wavelength band is achieved, and the reflectance is increased on the relatively short wavelength side so that the image display panel surface is bluish black and the quality of the image display panel is improved. Can be improved.

  The linearly polarizing plate 5 is configured by sandwiching an optical functional layer serving as a linearly polarizing plate between a pair of base materials. Here, the base material is a transparent film made of TAC (triacetylcellulose), poly (meth) methyl acrylate, poly (meth) butyl acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, ( A resin such as an acrylic resin such as a (meth) methyl acrylate-styrene copolymer, a glass such as soda glass, potassium glass, lead glass, and quartz glass can be applied. The optical functional layer is produced, for example, by adsorbing and orienting iodine compound molecules on a film material made of polyvinyl alcohol (PVA).

  The quarter-wave plate 6 includes a quarter-wave retardation layer 6A that imparts a quarter-wave phase difference to transmitted light, and a half-wave retardation layer that imparts a half-wave phase difference to transmitted light. The laminated body of 6B is arrange | positioned so that the linear polarizing plate 5 side may become the 1/2 wavelength phase difference layer 6B.

  Further, as shown in FIG. 2, the slow axis of the half-wave retardation layer 6 </ b> B is 20 degrees or more with respect to the absorption axis L of the linear polarizing plate 5 when viewed in plan from the linear polarizing plate 5 side. An angle θB of 25 degrees or less is formed, and the slow axis of the ¼ wavelength phase difference layer is arranged to form an angle θA of −5 degrees or more and 5 degrees or less. Alternatively, the angle θB may be set to 65 degrees or more and 70 degrees or less, and the angle θA may be set to 85 degrees or more and 95 degrees or less.

  When such angles θA and θB are set, the slow axis direction of the quarter-wave retardation layer 6A can be made substantially coincident with or orthogonal to the absorption axis direction of the linearly polarizing plate 5. . Thus, an optical film 3 is produced by laminating a quarter-wave retardation layer 6A having a similar long film shape on the linear polarizing plate 5 having a long shape wound on a roll before being cut into a sheet shape. The process at the time of carrying out can be simplified, and also a large-area optical film can be produced easily.

  Moreover, when comprised in this way, a highly versatile material, such as the stretched transparent film material, can be applied, for example, and the 1/4 wavelength phase difference layer 6A can be comprised, As a result, a highly versatile material is used. The optical film 3 can be produced by using it.

  On the other hand, the half-wave retardation layer 6B is made of a polymerizable liquid crystal material, and a slow axis is set in a direction that forms an angle θB with respect to the longitudinal direction of the base material in the shape of a long film. Can be produced. Thereby, also about the 1/2 wavelength phase difference layer 6B, the 1/2 wavelength phase difference layer 6B by a long film shape is laminated | stacked with the linearly polarizing plate 5 by the same long film shape, and the optical film 3 is produced. Or a laminated body of the quarter-wave retardation layer 6A and the half-wave retardation layer 6B in the shape of a long film is laminated with the linear polarizing plate 5 in the same long film shape to form the optical film 3. It is possible to produce a large-area optical film easily.

  More specifically, the half-wavelength retardation layer 6B is produced by an in-plane retardation Re2 (550) at a wavelength of 550 nm of 220 nm to 300 nm, preferably 230 nm to 280 nm, more preferably 240 nm to 275 nm. Is done. The phase difference at a wavelength of 550 nm of the ½ wavelength retardation layer 6B is preferably less than or equal to ½ of the wavelength 550 nm which is the luminous intensity wavelength. The quarter-wave retardation layer 6A desirably has a chromatic dispersion Re (450) / Re (550) larger than the chromatic dispersion Re (450) / Re (550) of the ½-wavelength retardation layer 6B.

  Here, the ½ wavelength retardation layer 6B and the ¼ wavelength retardation layer 6A are both positive dispersion materials having chromatic dispersion characteristics, and the ¼ wavelength retardation layer 6A has a short wavelength side (wavelength of 500 nm). Therefore, the phase difference at the wavelength 550 nm of the half-wavelength retardation layer 6B is reduced to 275 nm or less which is ½ or less of the wavelength 550 nm which is the luminous intensity wavelength. More preferably. The quarter-wave retardation layer 6A is produced with an in-plane retardation Re4 (550) at a wavelength of 550 nm of 100 nm to 160 nm, preferably 110 nm to 150 nm, more preferably 120 nm to 150 nm. Here, Re (λ) is the in-plane phase difference at the wavelength λ.

  Further, a difference value ΔRe = (subtracting the chromatic dispersion Re2 (450) / Re2 (550) of the ½ wavelength retardation layer from the chromatic dispersion Re4 (450) / Re4 (550) of the ¼ wavelength retardation layer 6A. Re4 (450) / Re4 (550) −Re2 (450) / Re2 (550)) is set to be −0.05 or more and 0.25 or less, whereby −0.05 ≦ ΔRe ≦ 0.25. It is set so as to satisfy the relational expression. Preferably, it is set so as to satisfy the relational expression of −0.05 ≦ ΔRe ≦ 0.20, more preferably satisfying the relational expression of 0 ≦ ΔRe ≦ 0.15.

  When setting so as to satisfy this relational expression, the wavelength dispersion characteristics of the quarter-wave retardation layer 6A and the half-wave retardation layer 6B can be balanced, and the optical By setting the color of the image display panel surface when viewed through the film 3 to be substantially black, the color of the panel surface can be improved.

  A stretched film material, which is a transparent film material having optical anisotropy, is applied to the quarter wavelength retardation layer 6A, and the half wavelength retardation layer 6B is formed by the quarter wavelength retardation layer 6A. A transparent film material is used as a base material, and an orientation layer is produced on the base material, and then the polymerizable liquid crystal material is cured by the orientation regulating force of the orientation layer.

  Here, in the stretched film according to the quarter-wave retardation layer 6A, although a film material having optical anisotropy can be widely applied, it is laminated with the linear polarizing plate 5 having a long film shape. From the viewpoint of securing the above-described angle θA in the direction of the slow axis and improving the productivity, the slow axis has an angle of −5 to 5 degrees with respect to the longitudinal direction produced by stretching. It is preferable to apply a film material formed or a film material formed at an angle of 85 degrees to 95 degrees. More specifically, a PEN (polyethylene naphthalate) film material or the like can be applied.

  On the other hand, the alignment layer is composed of a photo-alignment layer. Note that the photo-alignment layer can be manufactured using, for example, a light-dimerization type material, but is not limited to the light-dimerization-type material, and various photo-alignment layer materials can be widely applied. The alignment layer may be produced by a rubbing process, or may be produced by producing a fine line-shaped uneven shape by a shaping process.

  In the polymerizable liquid crystal material according to the half-wave retardation layer 6B, various liquid crystal materials applicable to this type of optical film can be widely applied.

  However, from the viewpoint of balancing the wavelength dispersion characteristics by setting the difference value ΔRe in the above-described range, the half-wave retardation layer 6B has in-plane retardations Re2 (450) and Re2 (550) with wavelengths of 450 nm and 550 nm. The chromatic dispersion Re2 (450) / Re2 (550) represented by using ## EQU1 ## is preferably 1.00 or more and 1.15 or less, more preferably -0.05 ≦ ΔRe ≦ 0.20 More preferably, it is set so as to satisfy the relational expression of 0 ≦ ΔRe ≦ 0.15.

  Further, from the same viewpoint, the ¼ wavelength retardation layer 6A preferably has a chromatic dispersion Re2 (450) / Re2 (550) of 1.04 or more and 1.25 or less, preferably 1.06 or more and 1. It is desirably 22 or less, and more desirably 1.08 or more and 1.20 or less.

  Specifically, various polymerizable liquid crystal compositions that are liquid crystal materials applicable to the A plate can be applied to the liquid crystal compound according to the quarter wavelength retardation layer 6B. Here, this polymerizable liquid crystal composition exhibits liquid crystallinity, and in addition to a liquid crystal compound having a polymerizable functional group in the molecule (hereinafter also referred to as “rod-like liquid crystal material”), a discotic liquid crystal can be applied. it can.

  The rod-shaped compound has a refractive index anisotropy, and has a function of imparting a desired phase difference by regularly arranging with an alignment regulating force of the alignment layer. Examples of the rod-like compound include materials exhibiting a liquid crystal phase such as a nematic phase and a smectic phase, but the nematic phase is easier to arrange regularly than liquid crystal compounds exhibiting other liquid crystal phases. It is more preferable to use the rod-shaped compound shown.

  Specific examples of the rod-shaped compound used in the present embodiment include compounds represented by the following formulas (1) to (17), and these compounds can be polymerized and used.

〔Manufacturing process〕
FIG. 3 is a flowchart showing a manufacturing process of the optical film 3. In this production process, in the 1/4 wavelength phase difference layer preparation step SP2, a transparent film material for the 1/4 wavelength phase difference layer 6A is produced, and the transparent film material is wound around a roll and oriented in a long film shape. This is provided to the layer manufacturing step SP3. In the light distribution layer preparation step, the transparent film material is coated with a coating liquid related to the photo-alignment layer and dried, and then linearly polarized ultraviolet rays whose angle θB is the polarization direction with respect to the longitudinal direction. Is used to set the alignment regulating force, thereby producing an alignment layer with the photo-alignment layer.

  Subsequently, in this manufacturing process, in the half-wave retardation layer manufacturing step SP4, the coating liquid related to the half-wave retardation layer 6B is applied and dried, and then cured by irradiation with ultraviolet rays. Is cured in a state where the polymerizable liquid crystal material is aligned by the alignment regulating force of the alignment layer, thereby producing the ½ wavelength retardation layer 6B. Thereby, this manufacturing process produces the quarter wavelength plate 6 with the form of a long film shape. In addition, after producing the laminated body of a 1/2 wavelength phase difference layer and a 1/4 wavelength phase difference layer in this way, instead of laminating | stacking with a linear polarizing plate, a 1/2 wavelength phase difference layer, 1 / You may make it produce an optical film by laminating | stacking 4 wavelength phase difference layer one by one.

  In this production process, in the lamination process SP5, the linear polarizing plate having the same long film shape is conveyed while being laminated with the quarter wavelength plate 6 having the same long film shape, thereby the optical film. 3 is produced. In this manufacturing process, after an adhesive layer is prepared on the optical film 3 and a separator film is disposed, the optical film 3 is cut into a desired size in the cutting process SP6. In this way, the optical film 3 is produced in a sheet shape, and is disposed on the panel surface (viewer side surface) of the image display panel by an adhesive layer that is exposed by peeling the separator film.

[Second Embodiment]
In this embodiment, a positive C plate layer is provided on the opposite side of the quarter-wave retardation layer 6A to the half-wave retardation layer 6B, thereby improving the viewing angle characteristics. This embodiment has the same configuration as that of the first embodiment except that the configuration related to the positive C plate layer is different.

  That is, in this embodiment, the C plate layer manufacturing step is provided before the 1/2 wavelength retardation layer 6B is manufactured or after the 1/2 wavelength retardation layer 6B is manufactured. In this C plate layer preparation step, the coating liquid for the vertical alignment layer is applied to the transparent film material for the quarter-wave retardation layer 6A, and then dried to prepare a vertical alignment layer. A positive C plate layer is produced by coating, drying and curing the coating solution relating to the plate layer.

  The positive C plate layer may be provided between the linearly polarizing plate and the ½ wavelength retardation layer, or may be provided between the ¼ wavelength retardation layer and the ½ wavelength retardation layer. It may be.

  Even when a positive C plate layer is provided as in this embodiment, the same effects as in the first embodiment can be obtained.

[Other Embodiments]
The specific configuration suitable for the implementation of the present invention has been described in detail above. However, the present invention is not limited to the scope of the present invention, and various combinations of the above-described embodiments, and further the configuration of the above-described embodiments. Can be variously changed.

  That is, in the above-described embodiment, the case where the film material is used as a base material by producing a quarter-wave retardation layer with a stretched film material has been described, but the present invention is not limited thereto, and the quarter is used. The wavelength retardation layer may be made of a polymerizable liquid crystal material in the same manner as the ½ wavelength retardation layer, and a substrate made of a transparent film material may be separately provided.

〔Example〕
FIG. 4 is a chart showing examples and comparative examples. In FIG. 4, Examples 1 to 3 are antireflection films according to the configuration of the first embodiment described above, and Example 4 is an antireflection film according to another embodiment described above. In Example 1, a polycarbonate film material (PC) having a thickness where the in-plane retardation Re (550) at a wavelength of 550 nm is 130 nm is applied to the quarter-wave retardation layer 6A, and the absorption axis of the linearly polarizing plate 5 is measured. The angle θA formed by the slow axis direction is 90 degrees. The wavelength dispersion Re (450) / Re (550) of this polycarbonate film material was 1.09. In Example 1, a photo-alignment layer and a half-wave retardation layer 6B were further formed on a substrate made of this polycarbonate film material.

  The half-wave retardation layer 6b is a mixture of the above-mentioned rod-like compounds (11) and (17) having a positive dispersion wavelength characteristic at a mixing ratio of 1: 1 and an initiator, BASF Irgacure. 907 and MegaFac (F477) manufactured by DIC were dissolved in a 1: 1 mixed solvent of methyl ethyl ketone and methyl isobutyl ketone to prepare a 25% solution, which was then coated using Miyabar # 3.

  This half-wavelength retardation layer 6B has an in-plane retardation Re (550) at a wavelength of 550 nm of 262 nm, and an angle θB formed in the slow axis direction with respect to the absorption axis of the linearly polarizing plate 5 is 23 degrees. Arranged. The chromatic dispersion Re (450) / Re (550) of the half-wave retardation layer 6B was 1.09.

  In Example 2, a polyethylene terephthalate film material (PET) having a thickness where the in-plane retardation Re (550) at a wavelength of 550 nm is 135 nm is applied to the quarter-wave retardation layer 6A, and the absorption axis of the linear polarizing plate 5 is applied. On the other hand, the angle θA formed in the slow axis direction is 90 degrees. The wavelength dispersion Re (450) / Re (550) was 1.12. Example 2 produced the photo-alignment layer and the 1/2 wavelength phase difference layer 6B on the base material by this film material like Example 1. FIG.

  In Example 2, the ½ wavelength retardation layer 6B has an in-plane retardation Re (550) of 265 nm at a wavelength of 550 nm, and an angle θB formed by the slow axis direction with respect to the absorption axis of the linearly polarizing plate 5 is. It arrange | positioned so that it might become 23 degree | times. The chromatic dispersion Re (450) / Re (550) of the half-wave retardation layer 6B was 1.09.

  In Example 3, a polyethylene naphthalate film material (PEN) having a thickness with an in-plane retardation Re (550) at a wavelength of 550 nm of 135 nm is applied to the quarter-wave retardation layer 6A, and the absorption axis of the linear polarizing plate 5 is applied. In contrast, the angle θA formed in the slow axis direction is 90 degrees. The wavelength dispersion Re (450) / Re (550) was 1.18. In Example 3, a photo-alignment layer and a half-wave retardation layer 6B were further produced on the base material of this film material in the same manner as in Example 1.

  In Example 3, the half-wave retardation layer 6B has an in-plane retardation Re (550) of 265 nm at a wavelength of 550 nm, and an angle θB formed by the slow axis direction with respect to the absorption axis of the linearly polarizing plate 5. Was arranged to be 23 degrees. The chromatic dispersion Re (450) / Re (550) of the half-wave retardation layer 6B was 1.09.

  In Example 4, a photo-alignment layer was produced on a transparent film material (PET film), and a quarter-wave retardation layer was formed on the photo-alignment layer in the same manner as the half-wave retardation layer of Example 1. 6A was produced. Note that the quarter-wave retardation layer 6A has an in-plane retardation Re (550) at a wavelength of 550 nm of 130 nm, and an angle θA formed in the slow axis direction with respect to the absorption axis of the linearly polarizing plate 5 is 90 degrees. It arranged so that it might become. The wavelength dispersion Re (450) / Re (550) was 1.09.

  In Example 4, a ½ wavelength retardation layer 6B is further laminated on the ¼ wavelength retardation layer 6A. The liquid crystal material according to the ½ wavelength phase difference layer 6B is the same as that of Example 1. The ½ wavelength phase difference layer 6B has an in-plane retardation Re (550) at a wavelength of 550 nm of 262 nm, and is linear. The angle θB formed in the slow axis direction with respect to the absorption axis of the polarizing plate 5 was arranged to be 23 degrees. The chromatic dispersion Re (450) / Re (550) of the half-wave retardation layer 6B was 1.09. The quarter-wave retardation layer 6A and the half-wave retardation layer 6B are laminated after the half-wave retardation layer 6B is laminated on the linearly polarizing plate 5 by the transfer method, and then the transfer method is similarly performed. The 1/4 wavelength phase difference layer 6A was laminated and executed.

  On the other hand, the comparative example 1 is the structure which produced the quarter wavelength plate with the cycloolefin polymer material (COP), and laminated | stacked with the linearly-polarizing plate. This quarter-wave plate has a thickness with an in-plane retardation Re (550) of 140 nm at a wavelength of 550 nm, and an angle θA formed in the slow axis direction with respect to the absorption axis of the linearly polarizing plate 5 is 45 degrees. Arranged. The wavelength dispersion Re (450) / Re (550) was 1.00.

  On the other hand, the comparative example 2 is the structure which produced the quarter wavelength plate with the polycarbonate material (PC), and was laminated | stacked with the linearly-polarizing plate. This quarter-wave plate has a thickness with an in-plane retardation Re (550) of 145 nm at a wavelength of 550 nm, and an angle θA formed in the slow axis direction with respect to the absorption axis of the linearly polarizing plate 5 is 45 degrees. Arranged. The chromatic dispersion Re (450) / Re (550) was 0.92.

  These examples and comparative examples are attached to the panel surface of an organic EL panel (55 inches) manufactured by LG Electronics, and regular reflectances Rf (450), Rf (550), and Rf (700) at wavelengths of 450 nm, 550 nm, and 700 nm. Was measured respectively. For measurement, CM3600 manufactured by Konica Minolta was used. According to this measurement result, the reflectance Rf increases on the long wavelength side in Comparative Examples 1 and 2, whereas in Examples 1 to 4, the chromatic dispersion Re (450) / Re (550) is reversed. Due to the dispersion characteristics, it was confirmed that the reflectance Rf was almost constant at wavelengths of 450 nm, 550 nm, and 700 nm. As a result, it was confirmed that sufficient reflection prevention can be achieved in a wide wavelength band in the visible light range. In particular, in Comparative Examples 1 and 2, the reflectance increases on the long wavelength side, whereby the image display panel surface is observed to be reddish, and as a result, the quality of the image display panel is significantly lowered and brought close to it. Become. However, in Examples 1 to 4, the reflectance increases relatively on the short wavelength side, so that the image display panel surface becomes bluish black, and in the case of this color, the quality of the image display panel is improved. be able to. By these Examples 1 to 4, it was confirmed that sufficient optical characteristics could be secured, and that a large-area material could be easily produced using a highly versatile material.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Image display panel 3 Optical film 4, 8 Adhesive layer 5 Linearly polarizing plate 6 1/4 wavelength plate 6A 1/4 wavelength phase difference layer 6B 1/2 wavelength phase difference layer

Claims (8)

In an optical film provided with a laminate of a linearly polarizing plate and a quarter-wave plate,
The quarter-wave plate is
From the linear polarizing plate side,
A half-wave retardation layer that imparts a half-wave phase difference to transmitted light;
A quarter-wave retardation layer for sequentially imparting a quarter-wave phase difference to the transmitted light,
Seen from the linear polarizing plate side, with respect to the absorption axis of the linear polarizing plate,
The slow axis of the ½ wavelength retardation layer forms an angle of 20 degrees or more and 25 degrees or less, or forms an angle of 65 degrees or more and 70 degrees or less,
An optical film in which the slow axis of the quarter-wave retardation layer forms an angle of −5 degrees to 5 degrees, or an angle of 85 degrees to 95 degrees. The optical film according to claim 1, wherein the half-wave retardation layer is formed of a polymerizable liquid crystal material. The difference value (Re4 (450) obtained by subtracting the wavelength dispersion Re2 (450) / Re2 (550) of the 1/2 wavelength retardation layer from the wavelength dispersion Re4 (450) / Re4 (550) of the 1/4 wavelength retardation layer. The optical film according to claim 1, wherein: / Re4 (550) −Re2 (450) / Re2 (550)) is −0.05 or more and 0.25 or less.
Where Re (λ) is the in-plane phase difference at the wavelength λ. The 1/2 wavelength retardation layer is
The optical film according to any one of claims 1, 2, and 3, wherein wavelength dispersion Re2 (450) / Re2 (550) is 1.00 or more and 1.15 or less. The quarter-wave retardation layer is
Stretched film material,
5. The optical film according to claim 1, wherein wavelength dispersion Re4 (450) / Re4 (550) is 1.04 or more and 1.25 or less. The 1/2 wavelength retardation layer is
In-plane retardation Re4 (550) at a wavelength of 550 nm is 220 nm or more and 270 nm or less,
The quarter-wave retardation layer is
The in-plane retardation Re4 (550) at a wavelength of 550 nm is 100 nm or more and 160 nm or less. The optical film according to claim 1, claim 2, claim 3, claim 4, or claim 5. An image display device in which the optical film according to any one of claims 1, 2, 3, 4, 5, and 6 is disposed on a panel surface of an image display panel. The image display panel is an image display panel using an organic EL element,
The image display device according to claim 7, wherein the reflectances Rf (450) and Rf (700) at wavelengths of 450 nm and 700 nm satisfy Rf (450)> Rf (700).