Coating method and method for manufacturing optical laminate

Abstract

Provided is an optical laminate that can contribute to improvement in visibility of an image display device. The coating method according to the present invention is a method for applying a coating liquid containing an adhesive layer forming material to a continuously conveyed sheet-shaped optical member using a gravure coating device, the gravure coating device comprising: a gravure roller having a coating region to which the coating liquid is to be adhered on the outer peripheral surface thereof; the gravure roller rotates in conjunction with the conveyance of the optical member. A chamber having, on a side surface thereof, a coating liquid supply unit for supplying the coating liquid to the rotating coating region; and a sealing blade that blocks a gap between the coating liquid supply unit and the surface of the coating region, the sealing blade having a protruding portion that protrudes toward the inside of the chamber and contacts the coating region, and the gravure roller is positioned further inside than the tip of the protruding portion of the sealing blade in the chamber.

Description

Technical Field

[0001] This invention relates to coating methods and methods for manufacturing optical laminates. Background Technology

[0002] Image display devices, represented by liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays), are rapidly becoming widespread. In image display devices, optical components such as polarizing members and phase difference members are generally used to achieve image display and improve image display performance (e.g., see Patent Document 1).

[0003] In recent years, new applications for image display devices have been developed. For example, goggles with displays (VR goggles) for realizing Virtual Reality (VR) have begun to be commercialized. The use of VR goggles in various scenarios has been studied, and their improved visual recognition, such as high precision, is highly anticipated.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-103286 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] As for VR goggles, since images are visually recognized through lenses, tiny foreign objects (such as air bubbles) present inside VR goggles tend to be easily visible.

[0009] In view of the above, one of the objects of the present invention is to provide an optical laminate that can help improve the visual recognizability of an image display device.

[0010] Problem Solving Methods

[0011] 1. The coating method according to an embodiment of the present invention is a method of applying a coating liquid containing an adhesive layer forming material to a sheet-like optical component that is continuously transported using a gravure coating apparatus. The gravure coating apparatus includes: a gravure roller having a coating area on its outer peripheral surface to which the coating liquid is to be applied, the gravure roller rotating in conjunction with the transport of the optical component; a chamber having a coating liquid supply portion on its side side for supplying the coating liquid to the coating area to be rotated; and a sealing blade sealing the gap between the coating liquid supply portion and the surface of the coating area, the sealing blade having a protrusion protruding toward the inner side of the chamber and contacting the coating area, wherein the gravure roller is located further inward than the front end of the protrusion of the sealing blade within the chamber.

[0012] 2. In the coating method described in 1 above, a space that is not filled with the coating liquid may be formed in the chamber.

[0013] 3. In the coating method described in 2 above, the distance between the upper surface of the coating liquid and the inner wall of the cavity can be 0.1 cm or more.

[0014] 4. In the coating method described in 2 or 3 above, the ratio A / B of the volume A of the coating liquid in the liquid storage section of the chamber to the volume B of the liquid storage section can be 0.5 to 0.99.

[0015] 5. In any one of the coating methods described in 1 to 4 above, the sealing blade may have a mounting portion and a protrusion, the mounting portion being detachably fixed to a blade support portion disposed near the gravure roller, the protrusion protruding from the blade support portion toward the gravure roller and contacting the coating area, and the length of the protrusion may be 20 mm or less.

[0016] 6. In the coating method described in 5 above, the ratio Y / X of the distance Y from the contact portion between the sealing blade and the gravure roller to the front end of the protrusion of the sealing blade to the length X of the protrusion is 0.5 or less.

[0017] 7. In any one of the coating methods described in 1 to 6 above, the rotational speed of the gravure roller can be from 10 times / minute to 300 times / minute.

[0018] 8. A method for manufacturing an optical laminate according to an embodiment of the present invention includes: forming a coating layer of adhesive layer forming material on a first optical component by any one of the coating methods described in 1 to 7; and laminating a second optical component on the first optical component via the coating layer.

[0019] 9. The manufacturing method described in 8 above may further include: forming a coating layer of adhesive layer forming material on the second optical component by any one of the coating methods described in 1 to 7 above, wherein the above-described lamination can be performed by bonding the coating layers together.

[0020] 10. In the manufacturing method described in 8 or 9 above, the formation of the coating layer and the lamination can be performed continuously.

[0021] The effects of the invention

[0022] The coating method according to embodiments of the present invention can provide an optical laminate that can help improve the visual recognizability of an image display device. Attached Figure Description

[0023] Figure 1 This is a schematic cross-sectional view showing a simplified configuration of the coating section of the gravure coating apparatus used in the coating method according to the first embodiment of the present invention.

[0024] Figure 2 yes Figure 1 A magnified view of the coated area shown.

[0025] Figure 3 This is a schematic cross-sectional view showing a simplified configuration of the coating section of the gravure coating apparatus used in the coating method according to the second embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram illustrating a simplified configuration of a display system for VR goggles.

[0027] Figure 5 This is a schematic cross-sectional view showing a detailed example of an optical laminate.

[0028] Symbol Explanation

[0029] 2 Display System

[0030] 4 Optical laminates

[0031] 6. Coating area

[0032] 12 display elements

[0033] 14. Reflective polarizing element

[0034] 16 First Lens Section

[0035] 18 Semi-reflective mirrors

[0036] 20 First λ / 4 component

[0037] 22 Second λ / 4 component

[0038] 24 Second Lens Section

[0039] 30 Protective components

[0040] 32 Phase difference components

[0041] 41 Adhesive layer

[0042] 42 Adhesive layer

[0043] 43 Adhesive layer

[0044] 50 chambers

[0045] 50a recess

[0046] 50b Blade Support

[0047] 50c inner wall

[0048] 51 Liquid delivery piping

[0049] 52 Liquid return piping

[0050] 53 Sealing Blade

[0051] 53a Protrusion

[0052] 53b Installation Department

[0053] 54 Pressing parts

[0054] 55 Liquid storage part

[0055] 56. Air Storage Section

[0056] 60 Gravure Roll

[0057] 61. Application area. Detailed Implementation

[0058] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to these embodiments. For clarity, the drawings sometimes schematically show the width, thickness, shape, etc., of various parts compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, regarding the drawings, sometimes the same or equivalent elements are labeled with the same symbols, and repeated descriptions are omitted.

[0059] (Definitions of terms and symbols)

[0060] The terms and symbols used in this manual are defined as follows.

[0061] (1) Refractive index (nx, ny, nz)

[0062] “nx” is the refractive index in the direction where the refractive index reaches its maximum in the plane (i.e., the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0063] (2) In-plane phase difference (Re)

[0064] “Re(λ)” is the in-plane phase difference measured at 23°C with light of wavelength λnm. For example, “Re(550)” is the in-plane phase difference measured at 23°C with light of wavelength 550nm. When the thickness of the layer (film) is set as d (nm), Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d.

[0065] (3) Phase difference (Rth) in the thickness direction

[0066] “Rth(λ)” is the phase difference in the thickness direction measured at 23°C using light with a wavelength of λnm. For example, “Rth(550)” is the phase difference in the thickness direction measured at 23°C using light with a wavelength of 550nm. When the thickness of the layer (film) is set as d (nm), Rth(λ) can be obtained using the formula: Rth(λ)=(nx-nz)×d.

[0067] (4) Nz coefficient

[0068] The coefficient of Nz can be obtained by Nz = Rth / Re.

[0069] (5) Angle

[0070] In this specification, when referring to an angle, the angle includes both clockwise and counterclockwise relative to a reference direction. Therefore, for example, "45°" means ±45°.

[0071] [Gravure Coating Device]

[0072] Figure 1 This is a schematic cross-sectional view showing a simplified configuration of the coating section of the gravure coating apparatus used in the coating method according to the first embodiment of the present invention. Figure 2 yes Figure 1 A magnified view of the coated area shown.

[0073] The coating section 6 consists of a chamber 50, a gravure roller 60, etc.

[0074] Chamber 50 is connected to a storage tank (not shown) for storing coating solution via a supply pipe 51, from which coating solution is supplied to chamber 50. The storage tank is also connected to chamber 50 via a return pipe 52, through which coating solution in chamber 50 can be returned to the storage tank. In this way, during application, the coating solution can circulate between the storage tank and chamber 50.

[0075] The chamber 50 is arranged along the gravure roller 60. On the side of the chamber 50 (the side opposite to the gravure roller 60), a recess (coating supply section) 50a is formed corresponding to the gravure roller 60, and the coating liquid is supplied to the gravure roller 60 through the chamber 50.

[0076] A sealing blade 53 is disposed on the lower side of the recess 50a. A blade support portion 50b with a flat blade support surface is provided along the lower edge of the recess 50a on the lower side of the recess 50a. A pressing member 54 is detachably mounted on the blade support portion 50b by means of bolts. The sealing blade 53 is detachably fixed to the chamber 50 by clamping the base end portion (mounting portion 53b) of the sealing blade 53 between the blade support portion 50b and the pressing member 54.

[0077] The sealing blade 53 is a plate-shaped component that seals the gap between the surface of the coating area 61 and the recess 50a. The front end portion (protrusion 53a) of the sealing blade 53 protrudes from the blade support portion 50b toward the gravure roller 60 and contacts the coating area 61.

[0078] The chamber 50 rests against the gravure roller 60 such that the sealing blade 53 is pressed against the coating area 61. This creates a space (reservoir section) 55 for storing coating liquid between the gravure roller 60 and the chamber 50. During coating, the reservoir section 55 is filled with coating liquid, thus the coating area 61 facing the reservoir section 55 is always in contact with the coating liquid, supplying coating liquid to the gravure roller 60.

[0079] The gravure roller 60 has a horizontally elongated cylindrical shape. For example, from the viewpoint of wear resistance, its surface is formed of ceramic or the like. The diameter of the gravure roller 60 is, for example, 10 mm to 1000 mm. The gravure roller 60 is arranged in contact with the surface of the sheet-like optical component S being transported. For example, the gravure roller 60 is supported by a frame (not shown) in a state where it can rotate freely about a horizontal axis. At the contact point with the optical component S, for example, it can be driven by a motor (not shown) to rotate in conjunction with the transport of the optical component S, causing its outer circumference to rotate in the opposite direction to the transport direction of the optical component S. The rotational speed of the gravure roller is, for example, 10 to 300 times per minute, preferably 35 to 100 times per minute.

[0080] Typically, a plurality of recesses (units) arranged in a uniform pattern are formed in the coating area 61 on the outer peripheral surface of the gravure roller 60. Coating liquid is continuously supplied from the chamber 50 to the coating area 61 surrounding the gravure roller 60 as it rotates, and the coating liquid adhering to the coating area 61 can be transferred to the surface of the transported optical component S.

[0081] Within the chamber 50 (liquid reservoir 55), the gravure roller 60 is located on the inner side relative to the tip (edge) of the protrusion 53a of the sealing blade 53 that contacts the gravure roller 60. By employing this positional relationship, air bubbles contained in the coating liquid adhering to the coating area 61 can be reduced. Even if air bubbles are generated, their size can be reduced. Specifically, by reducing the length (protrusion degree) of the protrusion 53a of the sealing blade 53, the vibration of the sealing blade 53 itself can be suppressed, thereby suppressing the generation of air bubbles in the coating liquid.

[0082] The length X of the protrusion 53a of the sealing blade 53 is, for example, greater than 0 mm and less than 20 mm, and may be less than 15 mm. The ratio Y of the distance Y from the contact portion 53c between the sealing blade 53 and the gravure roller 60 to the front end of the protrusion 53a of the sealing blade 53 to the length X of the protrusion 53a is, for example, greater than 0 and less than 0.5, and may be less than 0.3 or less, or less than 0.1.

[0083] During application, it is preferable to form an unfilled space (air accumulation section) 56 within the chamber 50 (liquid storage section 55). By forming the air accumulation section 56, air bubbles generated in the liquid can easily escape, thereby reducing the number of air bubbles contained in the liquid adhering to the application area 61.

[0084] The distance between the upper surface of the coating liquid and the inner wall 50c of the chamber 50 is, for example, 0.1 cm or more, and can be 1 cm or more. It should be noted that the distance between the upper surface of the coating liquid and the inner wall 50c of the chamber 50 can correspond to the height of the air accumulation section 56. The ratio A / B of the volume A of the coating liquid in the liquid storage section 55 to the volume B of the liquid storage section 55 is, for example, 0.5 to 0.99.

[0085] The thickness of the sealing blade 53 is, for example, 0.1 mm or more and 1 mm or less, and can be 0.5 mm or less.

[0086] The coating liquid contains an adhesive layer forming material. For example, the coating liquid can be an adhesive or a binder. The viscosity of the coating liquid at 23°C is, for example, 25 mPa·s to 50 mPa·s, preferably 27 mPa·s to 47 mPa·s.

[0087] Figure 3 This is a schematic cross-sectional view showing a simplified configuration of the coating section of the gravure coating apparatus used in the coating method according to the second embodiment of the present invention. In the second embodiment, unlike the first embodiment, the liquid storage section 55 is formed such that its upper end (upper inner wall 50c) is located above the liquid delivery pipe 51. In this way, an air accumulation section 56 can be formed within the chamber 50 even without controlling the circulation of the coating liquid.

[0088] [Optical laminate]

[0089] Typically, the above-described gravure coating apparatus is used to form an adhesive layer forming material coating layer on the first optical component, and the second optical component is then laminated through this coating layer to obtain an optical laminate. The thickness of the coating layer varies depending on the composition of the adhesive layer forming material, and is typically 0.5 μm to 50 μm, but can be 0.5 μm to 15 μm. When the first optical component and the second optical component are laminated, the above-described gravure coating apparatus can also be used to form an adhesive layer forming material coating layer on the second optical component. In this case, the coating layer formed on the first optical component and the coating layer formed on the second optical component can be bonded together for lamination.

[0090] For example, from a manufacturing efficiency perspective, the coating layers are formed and stacked continuously. The coating layers obtained using the aforementioned gravure coating apparatus have fewer air bubbles and can be stacked immediately after coating.

[0091] By using the aforementioned gravure coating apparatus, optical laminates with fewer air bubbles can be obtained, for example. Typically, optical laminates can be applied to image display devices. By incorporating optical laminates with fewer air bubbles, image display devices with excellent visual recognition can be achieved. In image display devices, air bubbles contained in the optical laminate can sometimes affect visual recognition. Specifically, air bubbles contained in the optical laminate can sometimes be visually perceived as defects. The higher the precision of the image display device, the more stringent the defect management of the components constituting the image display device becomes. Therefore, using optical laminates with fewer air bubbles can help improve the visual recognition of the image display device. In VR goggles, air bubbles may enlarge and tend to be easily visually perceived as defects; therefore, using optical laminates with fewer air bubbles can significantly improve visual recognition.

[0092] Figure 4 This is a schematic diagram illustrating a simplified configuration of a display system for VR goggles, showing the arrangement and shape of each component. The display system 2 includes a display element 12, a reflective polarizing member 14, a first lens portion 16, a semi-reflective mirror 18, a first λ / 4 member 20, a second λ / 4 member 22, and a second lens portion 24. The reflective polarizing member 14 is disposed on the display surface 12a side of the display element 12, i.e., in front, and can reflect light emitted from the display element 12. The first lens portion 16 is disposed in the optical path between the display element 12 and the reflective polarizing member 14, and the semi-reflective mirror 18 is disposed between the display element 12 and the first lens portion 16. The first λ / 4 member 20 is disposed in the optical path between the display element 12 and the semi-reflective mirror 18, and the second λ / 4 member 22 is disposed in the optical path between the semi-reflective mirror 18 and the reflective polarizing member 14.

[0093] The display element 12 is, for example, a liquid crystal display or an organic EL display, having a display surface 12a for displaying images. Light emitted from the display surface 12a passes through a polarizing member that may be included in the display element 12 and becomes first linearly polarized light.

[0094] The first λ / 4 component 20 can convert the first linearly polarized light incident on the first λ / 4 component 20 into the first circularly polarized light. The first λ / 4 component 20 can be integrally disposed on the display element 12.

[0095] The semi-reflective mirror 18 allows light emitted from the display element 12 to pass through and reflects light that has been reflected by the reflective polarizing member 14 toward the reflective polarizing member 14. The semi-reflective mirror 18 is integrally disposed on the first lens portion 16.

[0096] The second λ / 4 member 22 allows light that has been reflected by the reflective polarizing member 14 and the half-reflector 18 to pass through the reflective polarizing member 14. The second λ / 4 member 22 can be integrally disposed on the first lens section 16.

[0097] The first circularly polarized light emitted from the first λ / 4 member 20 passes through the half-reflector 18 and the first lens section 16, and is converted into second linearly polarized light by the second λ / 4 member 22. The second linearly polarized light emitted from the second λ / 4 member 22 does not pass through the reflective polarizing member 14, but is reflected towards the half-reflector 18. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing member 14 is the same as the reflection axis of the reflective polarizing member 14. Therefore, the second linearly polarized light incident on the reflective polarizing member 14 is reflected by the reflective polarizing member 14.

[0098] The second linearly polarized light, after being reflected by the reflective polarizing member 14, is converted into second circularly polarized light by the second λ / 4 member 22. The second circularly polarized light exiting from the second λ / 4 member 22 is reflected by the half-reflector 18 after passing through the first lens section 16. The second circularly polarized light, after being reflected by the half-reflector 18, passes through the first lens section 16 and is converted into third linearly polarized light by the second λ / 4 member 22. The third linearly polarized light is transmitted through the reflective polarizing member 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing member 14 is the same as the transmission axis of the reflective polarizing member 14. Therefore, the third linearly polarized light incident on the reflective polarizing member 14 is transmitted through the reflective polarizing member 14.

[0099] Light passing through the reflective polarizing member 14 passes through the second lens section 24 and then enters the user's eye 26.

[0100] The absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14 can be arranged approximately parallel to each other or approximately orthogonal. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the first λ / 4 member 20 is, for example, 40°~50°, 42°~48°, or approximately 45°. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the second λ / 4 member 22 is, for example, 40°~50°, 42°~48°, or approximately 45°.

[0101] The in-plane phase difference Re(550) of the first λ / 4 component 20 is, for example, 100nm~190nm, 110nm~180nm, 130nm~160nm, or 135nm~155nm. The first λ / 4 component 20 preferably exhibits an inverse dispersion wavelength characteristic where the phase difference value increases corresponding to the wavelength of the measured light. The Re(450) / Re(550) of the first λ / 4 component 20 is, for example, 0.75 or more and less than 1, and can be 0.8 or more and less than 0.95.

[0102] The in-plane phase difference Re(550) of the second λ / 4 member 22 is, for example, 100nm~190nm, 110nm~180nm, 130nm~160nm, or 135nm~155nm. The second λ / 4 member 22 preferably exhibits an inverse dispersion wavelength characteristic where the phase difference value increases corresponding to the wavelength of the measured light. The Re(450) / Re(550) of the second λ / 4 member 22 is, for example, 0.75 or more and less than 1, and can be 0.8 or more and less than 0.95.

[0103] Although not shown in the figure, the display system 10 may include an absorptive polarizing member disposed in front of the reflective polarizing member 14. The reflection axis of the reflective polarizing member and the absorption axis of the absorptive polarizing member may be arranged substantially parallel to each other.

[0104] The optical laminate of embodiments of the present invention may include components such as those found in the aforementioned display system. Specifically, the optical laminate may include polarization components (e.g., reflective polarization components, absorptive polarization components), phase difference components such as λ / 4 components, optical components such as protective components, and adhesive layers for integrating adjacent components.

[0105] The adhesive layer included in the optical laminate can be a layer formed by applying a coating liquid containing an adhesive layer forming material using the above-described gravure coating apparatus and then curing or solidifying it. When the adhesive layer is an adhesive layer, its thickness is typically 0.5 μm to 5 μm. When the adhesive layer is an adhesive layer, its thickness is typically 5 μm to 50 μm. The size of air bubbles that may be contained in the adhesive layer is preferably less than 20 μm, more preferably less than 15 μm. Even if the adhesive layer contains air bubbles, if they are of such a size, extremely excellent visual recognition can be achieved in image display devices (e.g., VR goggles). It should be noted that the size of the air bubbles can be determined by observation, for example, using an optical microscope. In one embodiment, the proportion of air bubbles with a size of 20 μm or more among all air bubbles contained in an adhesive layer is preferably 5% or less, more preferably 1% or less.

[0106] Figure 5 This is a schematic cross-sectional view illustrating an example of the details of an optical laminate. The optical laminate 4 includes: a first λ / 4 member 20, a polarizing member 12b disposed on one side of the first λ / 4 member 20, and a protective member 30 disposed on the other side of the first λ / 4 member 20. The polarizing member 12b may correspond to a polarizing member that may be included in the aforementioned display element (display element 12). The polarizing member 12b typically includes at least an absorptive polarizing film, which can be formed by laminating the protective layer to one or both sides of the absorptive polarizing film via an adhesive layer (not shown). In addition to the first λ / 4 member 20, the optical laminate 4 also includes another phase difference member 32. In the example shown, the phase difference member 32 is disposed between the first λ / 4 member 20 and the polarizing member 12b, but it may also be disposed, for example, between the first λ / 4 member 20 and the protective member 30. The members are laminated together via adhesive layers 41, 42, and 43. Although not illustrated, the optical laminate 4 may further include additional phase retardation components. For example, an additional phase retardation component may be disposed between the polarizing component 12b and the phase retardation component 32 via an adhesive layer. In this case, the additional phase retardation component can also serve as a protective layer for the absorptive polarizing film. In the above-described display system, particularly stringent defect management is required for the optical laminate 4, which can be integrally disposed with the display element 12. At least one layer of the adhesive layer included in the optical laminate 4 can be formed by applying a coating liquid containing an adhesive layer forming material using the above-described gravure coating apparatus. In this way, the optical laminate 4 can achieve extremely excellent visual recognition in VR goggles through strict defect management.

[0107] The refractive index characteristics of the preferred first λ / 4 member 20 exhibit a relationship of nx > ny ≥ nz. Here, "ny = nz" includes not only the case where ny and nz are exactly equal, but also the case where they are substantially equal. Therefore, sometimes ny < nz. The Nz coefficient of the first λ / 4 member 20 is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0108] The first λ / 4 member 20 can be formed from any suitable material capable of satisfying the above characteristics. The first λ / 4 member 20 can be, for example, a stretched film of a resin film or an orientation fixing layer of a liquid crystal compound.

[0109] Examples of resins included in the aforementioned resin film include: polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, and acrylic resins. These resins can be used alone or in combination. Examples of methods of combination include blending and copolymerization. When the first λ / 4 component 20 exhibits inverse dispersion wavelength characteristics, a resin film containing polycarbonate resins or polyester carbonate resins (hereinafter, sometimes simply referred to as polycarbonate resins) can be suitably used.

[0110] As the aforementioned polycarbonate resin, any suitable polycarbonate resin can be used. For example, the polycarbonate resin comprises structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from at least one dihydroxy compound selected from alicyclic diols, alicyclic diethanols, di-, tri-, or polyethylene glycols, and alkylene diols or spirodiols. Preferably, the polycarbonate resin comprises structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from alicyclic diethanols and / or structural units derived from di-, tri-, or polyethylene glycols; more preferably, it comprises structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di-, tri-, or polyethylene glycols. The polycarbonate resin may also, as needed, comprise structural units derived from other dihydroxy compounds. It should be noted that details of the polycarbonate resin suitable for the first λ / 4 component 20 and the method for forming the first λ / 4 component 20 are described, for example, in Japanese Patent Application Publication Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, and 2015-212818, and the descriptions in these publications are incorporated herein by reference.

[0111] The thickness of the first λ / 4 member 20, which is a stretched film of resin film, is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, and more preferably 20 μm to 60 μm.

[0112] The aforementioned alignment-fixing layer of the liquid crystal compound is a layer in which the liquid crystal compound is aligned in a given direction within the layer, and its alignment state is fixed. It should be noted that "alignment-fixing layer" includes the concept of an alignment-cured layer obtained by curing liquid crystal monomers as described later. In the first λ / 4 member 20, typically, rod-shaped liquid crystal compounds are aligned (homogeneous alignment) in a state aligned along the slow axis direction of the first λ / 4 member 20. Examples of rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably capable of polymerization. If the liquid crystal compound is capable of polymerization, the alignment state of the liquid crystal compound can be fixed by polymerization after aligning the liquid crystal compound.

[0113] The alignment layer (liquid crystal alignment layer) of the aforementioned liquid crystal compound can be formed by the following method: an alignment treatment is performed on the surface of a given substrate; a coating liquid containing the liquid crystal compound is applied to the surface; the liquid crystal compound is aligned along a direction corresponding to the alignment treatment; and the alignment state is fixed. Any suitable alignment treatment can be used. Examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. Specific examples of mechanical alignment treatment include friction treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include tilting vapor deposition and photo-alignment treatment. The processing conditions for each alignment treatment can be any suitable condition depending on the purpose.

[0114] The orientation of a liquid crystal compound can be achieved by processing it at a temperature that displays a liquid crystal phase, depending on the type of liquid crystal compound. Through such temperature processing, the liquid crystal compound is in a liquid crystal state and is oriented in accordance with the orientation processing direction of the substrate surface.

[0115] In one embodiment, the orientation state is fixed by cooling the oriented liquid crystal compound as described above. If the liquid crystal compound is polymerizable or crosslinkable, the orientation state can be fixed by performing a polymerization or crosslinking treatment on the oriented liquid crystal compound as described above.

[0116] As the aforementioned liquid crystal compound, any suitable liquid crystal polymer and / or liquid crystal monomer can be used. The liquid crystal polymer and liquid crystal monomer can be used alone or in combination. Specific examples of liquid crystal compounds and methods for fabricating liquid crystal alignment fixing layers are described, for example, in Japanese Patent Application Publication No. 2006-163343, Japanese Patent Application Publication No. 2006-178389, and International Publication No. 2018 / 123551. The contents of these publications are incorporated herein by reference.

[0117] The thickness of the first λ / 4 member 20, which is composed of a liquid crystal alignment fixing layer, is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and even more preferably 1 μm to 4 μm.

[0118] As a polarizing element 12b, it may, for example, comprise a resin film containing a dichroic substance (sometimes called an absorptive polarizing film). The thickness of the absorptive polarizing film may be, for example, 1 μm or more and 20 μm or less, 2 μm or more and 15 μm or less, 12 μm or less, 10 μm or less, 8 μm or less, or 5 μm or less.

[0119] The aforementioned absorptive polarizing film can be made from a single layer of resin film or from a laminate of two or more layers.

[0120] In the case of a single-layer resin film, for example, an absorptive polarizing film can be obtained by subjecting hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formaldehyde-treated PVA films, and partially saponified ethylene-vinyl acetate copolymer films to dyeing treatments using dichroic substances such as iodine and dichroic dyes, and stretching treatments. Among these, an absorptive polarizing film obtained by dyeing a PVA film with iodine and then uniaxially stretching it is preferred.

[0121] The above-mentioned dyeing using iodine can be carried out, for example, by immersing the PVA film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or during dyeing. Alternatively, dyeing can be performed after stretching. Swelling treatment, crosslinking treatment, cleaning treatment, drying treatment, etc., can be applied to the PVA film as needed.

[0122] Examples of laminates made using two or more layers include a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and a PVA-based resin layer coated on the resin substrate. An absorptive polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured by: for example, coating a PVA-based resin solution onto a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form an absorptive polarizing film from the PVA-based resin layer. In this embodiment, it is preferable to form a polyvinyl alcohol resin layer comprising a halide and a polyvinyl alcohol resin on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may, as needed, further include stretching the laminate in a gas atmosphere at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. Furthermore, in this embodiment, it is preferable to subject the laminate to a drying shrinkage treatment, which causes it to shrink by more than 2% in the width direction by heating while being transported along the length direction. Typically, the manufacturing method of this embodiment includes sequentially subjecting the laminate to assisted stretching in a gas atmosphere, dyeing, stretching in an aqueous solution, and drying shrinkage treatment. By introducing assisted stretching, even when PVA is coated on a thermoplastic resin substrate, the crystallinity of PVA can be improved, achieving high optical properties. Additionally, by simultaneously improving the orientation of PVA beforehand, problems such as decreased orientation and dissolution of PVA during subsequent dyeing and stretching processes when immersed in water can be prevented, achieving high optical properties. Furthermore, when the PVA-type resin layer is immersed in a liquid, compared to when the PVA-type resin layer does not contain halides, the orientation disorder of polyvinyl alcohol molecules and the reduction of orientation can be suppressed. Therefore, the optical properties of the absorptive polarizing film obtained by immersing the laminate in a liquid through dyeing and stretching processes in an aqueous solution can be improved. Furthermore, by drying and shrinking the laminate in the width direction, optical properties can be improved. The resulting resin substrate / absorbent polarizing film laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the absorbent polarizing film), or the resin substrate can be peeled off from the resin substrate / absorbent polarizing film laminate, and any suitable protective layer corresponding to the purpose can be laminated on the peeled surface or on the side opposite to the peeled surface. Detailed descriptions of such a method for manufacturing an absorbent polarizing film are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0123] Typically, the protective member 30 includes a substrate. The substrate can be composed of any suitable film. Examples of materials that form the main component of the film constituting the substrate include: cellulose resins such as cellulose triacetate (TAC), polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrene, cycloolefins such as polynorbornene, polyolefins, (meth)acrylic acids, acetates, etc. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 40 μm.

[0124] The protective member 30 preferably has a surface treatment layer formed on the substrate in addition to the substrate. The protective member with the surface treatment layer can be arranged such that its substrate is located on the side of the first λ / 4 member 20. The surface treatment layer can have any suitable function. The surface treatment layer preferably has, for example, an anti-reflective function. The thickness of the surface treatment layer is preferably 0.5 μm to 10 μm, more preferably 1 μm to 7 μm, and even more preferably 2 μm to 5 μm.

[0125] The phase retardation member 32 can have any suitable refractive index characteristics. For example, the refractive index characteristics of the phase retardation member 32 show the relationship nz>nx≥ny. By using the member 32 that shows the relationship nz>nx≥ny, light leakage (e.g., oblique light leakage) can be prevented.

[0126] The phase difference Rth(550) in the thickness direction of the phase retardation member 32, which exhibits the refractive index characteristics of nz>nx≥ny, is preferably -260nm to -10nm, more preferably -230nm to -15nm, and even more preferably -215nm to -20nm. In one embodiment, the phase retardation member 32 is a so-called positive C-plate whose refractive index exhibits the relationship nx=ny. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. For example, it also includes the case where Re(550) is less than 10nm. In another embodiment, the refractive index of the phase retardation member 32 exhibits the relationship nx>ny. In this case, the in-plane phase difference Re(550) of the phase retardation member 32 is preferably 10nm to 150nm, more preferably 10nm to 80nm.

[0127] The phase difference member 32, whose refractive index characteristics show a relationship of nz>nx≥ny, can be formed from any suitable material. Preferably, it is composed of a film containing a liquid crystal material fixed in a vertical orientation. The liquid crystal material (liquid crystal compound) capable of vertical orientation can be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and film formation methods can be the liquid crystal compounds and formation methods described in Japanese Patent Application Publication Nos. 2002-333642

[0020] to

[0042] . In this case, the thickness is preferably 0.1 μm to 5 μm, more preferably 0.5 μm to 4 μm.

[0128] As another preferred specific example, the phase retardation member 32, whose refractive index characteristics show a relationship of nz>nx≥ny, can be a phase retardation film formed of a fumarate diester resin as described in Japanese Patent Application Publication No. 2012-32784. In this case, the thickness is preferably 5μm to 50μm, more preferably 10μm to 35μm.

[0129] The refractive index characteristics of the aforementioned additional phase retardation components exhibit, for example, a relationship of nx > ny > nz. The in-plane phase difference Re(550) of the phase retardation components exhibiting this refractive index relationship is preferably 80 nm to 150 nm, more preferably 90 nm to 140 nm, and even more preferably 100 nm to 130 nm. The Nz coefficient is, for example, 1.1 to 3.0.

[0130] Example

[0131] The present invention will now be described in detail with reference to specific embodiments, but the present invention is not limited to these embodiments. It should be noted that the thickness, in-plane phase difference, and viscosity are values ​​measured by the methods described below.

[0132] <Thickness>

[0133] Thicknesses below 10 μm were measured using a scanning electron microscope (manufactured by Nippon Electron Ltd., product name "JSM-7100F"). Thicknesses exceeding 10 μm were measured using a digital micrometer (manufactured by Anritsu Ltd., product name "KC-351C").

[0134] <In-plane phase difference Re(λ)>

[0135] Square samples with a width of 50 mm and a length of 50 mm were cut from the central portion and both ends of the membrane along its width direction, with one side parallel to the width direction of the membrane. The in-plane phase difference of the sample at various wavelengths at 23°C was measured using a Mueller matrix polarimeter (Axometrics product name "Axoscan").

[0136] <Viscosity>

[0137] Viscosity was measured at 23°C using a dynamic viscoelasticity measuring device (TV-25 viscometer manufactured by Toki Sangyo Co., Ltd.).

[0138] [Example 1]

[0139] (Fabrication of λ / 4 components)

[0140] Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled at 100°C. The feed consisted of 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluorene-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spirodiol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10⁻⁶ mol of calcium acetate monohydrate as a catalyst. -2 Parts by weight (6.78 × 10) -5 (mol). After purging the reactor with nitrogen under reduced pressure, heating was performed using a heat transfer medium. Stirring was initiated when the internal temperature reached 100°C. The internal temperature was raised to 220°C 40 minutes after the start of heating. While maintaining this temperature, the pressure was reduced, reaching 13.3 kPa after 90 minutes. Phenolic vapors produced as a byproduct of the polymerization reaction were introduced into a 100°C reflux condenser, allowing a certain amount of monomer components contained in the phenol vapors to return to the reactor, while the uncondensed phenol vapors were recovered in a 45°C condenser. Nitrogen was introduced into the first reactor to temporarily restore atmospheric pressure, and the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Then, heating and depressurization were initiated in the second reactor, reaching an internal temperature of 240°C and a pressure of 0.2 kPa after 50 minutes. Polymerization was then allowed to proceed until the given stirring power was reached. At the moment when the given power is reached, nitrogen is introduced into the reactor to restore the pressure, the generated polyester carbonate resin is extruded into the water, and the wire is cut to obtain granules.

[0141] The obtained polyester carbonate resin (granules) was vacuum dried at 80°C for 5 hours. A strip-shaped resin film with a thickness of 135 μm was then produced using a film-forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a chilled roll (set temperature: 120~130°C), and a winding machine. The obtained strip-shaped resin film was stretched along its width at a stretching temperature of 143°C and a stretch ratio of 2.8 times to obtain a stretched film with a thickness of 47 μm. The resulting stretched film had a Re(550) of 143 nm, a Re(450) / Re(550) ratio of 0.86, and an Nz coefficient of 1.12.

[0142] (Preparation of adhesive)

[0143] An adhesive with a viscosity of 27-47 mPa·s was prepared by mixing 62 parts by weight of hydroxyethyl acrylamide (manufactured by Kojin Co., Ltd., trade name "HEAA"), 25 parts by weight of acryloylmorpholine (manufactured by Kojin Co., Ltd., trade name "ACMO"), 7 parts by weight of PEG400# diacrylate (manufactured by Kyoei Chemical Co., Ltd., trade name "LIGHT ACRYLATE 9EG-A"), 3 parts by weight of BASF's trade name "IRGACURE 907", and 3 parts by weight of Nippon Kayaku Co., Ltd.'s trade name "KAYACURE DETX-S" for 60 minutes.

[0144] (Preparation of the coating layer)

[0145] use Figure 1 The gravure coating apparatus shown applies the adhesive to the λ / 4 member (stretch film) to achieve a cured thickness of 1.5~2.5 μm, forming a coating layer. During coating, the adhesive is applied to the λ / 4 member (stretch film) to achieve a cured thickness of 1.5~2.5 μm. Figure 2 The length X of the protrusion 53a of the sealing blade 53 shown is set to 15 mm, and a sealing blade with a thickness of 0.2 mm is used. The distance Y from the contact portion 53c between the sealing blade 53 and the gravure roller 60 to the front end of the protrusion 53a of the sealing blade 53 is 5 mm.

[0146] [Comparative Example 1]

[0147] When applying the adhesive, as follows Figure 2 The length X of the protrusion 53a of the sealing blade shown is set to 24 mm, and a sealing blade with a thickness of 0.3 mm is used. Otherwise, the same procedure as in Embodiment 1 is followed, and a coating layer is formed on the λ / 4 component. The distance Y from the contact portion 53c between the sealing blade 53 and the gravure roller 60 to the front end of the protrusion 53a of the sealing blade 53 is 14 mm.

[0148] The number of bubbles in the coatings obtained in Example 1 and Comparative Example 1 was counted by observing them with an optical microscope. The evaluation results are shown in Table 1.

[0149]

[0150] This invention is not limited to the embodiments described above and can be modified in various ways. For example, it can be replaced with a configuration that is substantially the same as the configuration shown in the above embodiments, a configuration that performs the same function, or a configuration that achieves the same purpose.

[0151] Industrial applicability

[0152] The coating method of the present invention can be used to manufacture optical laminates suitable for use in image display devices such as VR goggles.

Claims

1. A coating method comprising applying a coating liquid containing an adhesive layer forming material to a continuously transported sheet-like optical component using a gravure coating apparatus. The gravure coating apparatus includes: A gravure roller having a coating area on its outer peripheral surface to which the coating liquid is to be applied rotates in conjunction with the transport of the optical component; A chamber for supplying the coating liquid to the coating area on the side; as well as A sealing blade that seals the gap between the coating supply section and the surface of the coating area. The sealing blade has a protrusion that extends toward the inner side of the cavity and contacts the coating area. Within the chamber, the gravure roller is located further inward than the front end of the protrusion of the sealing blade.

2. The application method according to claim 1, wherein, The chamber contains a space that is not filled with the coating liquid.

3. The application method according to claim 2, wherein, The distance between the upper surface of the coating liquid and the inner wall of the cavity is more than 0.1 cm.

4. The application method according to claim 2, wherein, The ratio A / B of the volume A of the coating liquid in the reservoir of the chamber to the volume B of the reservoir is 0.5 to 0.

99.

5. The application method according to claim 1, wherein, The sealing blade has a mounting portion and a protrusion. The mounting portion is detachably fixed to a blade support portion disposed near the gravure roller. The protrusion extends from the blade support portion toward the gravure roller and contacts the coating area. The length of the protrusion is less than 20 mm.

6. The application method according to claim 5, wherein, The ratio Y / X of the distance Y from the contact point between the sealing blade and the gravure roller to the front end of the protrusion of the sealing blade to the length X of the protrusion is 0.5 or less.

7. The application method according to claim 1, wherein, The rotational speed of the gravure roller is 10 times / minute to 300 times / minute.

8. A method for manufacturing an optical laminate, comprising: The coating layer of the material is formed by forming an adhesive layer on the first optical component using the coating method described in claim 1; and The second optical component is stacked on the first optical component via the coating layer.

9. The method for manufacturing an optical laminate according to claim 8, further comprising: The coating layer of the material is formed in the second optical component by the coating method described in claim 1 to form an adhesive layer. The lamination is performed by bonding the coating layers together.

10. The method for manufacturing an optical laminate according to claim 8, wherein, The formation and stacking of the coating layer are performed continuously.

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