Coating method and method for producing optical laminate

Abstract

To provide an optical laminate capable of contributing to improvement of visibility of an image display device.SOLUTION: A coating method coats coating liquid containing an adhesive layer formation material onto a continuously conveyed sheet-like optical member using a gravure coating device, wherein the gravure coating device includes a gravure roll which has a coating region where the coating liquid is attached on its outer peripheral surface and is rotated in conjunction with conveyance of the optical member, a chamber having a coating liquid supply part for supplying the coating liquid to the circulated coating region on its side surface, and a seal blade for blocking a gap between the coating liquid supply part and the surface of the coating liquid, the seal blade has a projection part which projects to the chamber inside and is brought into contact with the coating region, and in the chamber, the gravure roll is positioned inside a tip of the projection part of the seal blade.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coating method and a method for producing an optical laminate. [Background technology]

[0002] Image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices), are rapidly becoming popular. In image display devices, optical components such as polarizing components and phase difference components are generally used to realize image display and improve the performance of the image display (see, for example, 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. VR goggles are being considered for use in a variety of situations, and improvements in visibility, such as higher resolution, are desired. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-103286 Summary of the Invention [Problem to be solved by the invention]

[0005] In VR goggles, images are viewed through lenses, so minute foreign objects (for example, air bubbles) present inside the VR goggles tend to be easily visible.

[0006] In view of the above, one object of the present invention is to provide an optical laminate that can contribute to improving the visibility of an image display device. [Means for solving the problem]

[0007] 1. A 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 element that is being continuously transported using a gravure coating device, wherein the gravure coating device comprises a gravure roll that has a coating area on its outer surface to which the coating liquid adheres and that rotates in conjunction with the transport of the optical element, a chamber that has a coating liquid supply unit on its side that supplies the coating liquid to the coating area as it rotates, and a seal blade that closes the gap between the coating liquid supply unit and the surface of the coating area, wherein the seal blade protrudes toward the inside of the chamber and has a protrusion that contacts the coating area, and within the chamber, the gravure roll is positioned inside the tip of the protrusion of the seal blade. 2. In the coating method described in 1 above, the chamber may have a space formed therein that is not filled with the coating liquid. 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 chamber may be 0.1 cm or more. 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 reservoir of the chamber to the volume B of the liquid reservoir in which the coating liquid is stored may be 0.5 to 0.99. 5. In the coating method described in any one of 1 to 4 above, the seal blade may have an attachment portion that is detachably fixed to a blade support portion arranged near the gravure roll, and a protrusion that protrudes from the blade support portion toward the gravure roll and contacts the coating area, and the length of the protrusion may be 20 mm or less. 6. The coating method according to claim 5, wherein the ratio Y / X of the distance Y from the contact point between the seal blade and the gravure roll to the tip of the protrusion of the seal blade to the length X of the protrusion is 0.5 or less. 7. In the coating method according to any one of the above 1 to 6, the rotation speed of the gravure roll may be 10 rpm to 300 rpm.

[0008] 8. A method for producing an optical laminate according to an embodiment of the present invention includes forming a coating layer of an adhesive layer-forming material on a first optical element by a coating method described in any one of 1 to 7 above, and laminating a second optical element on the first optical element via the coating layer. 9. The manufacturing method described in 8 above may further include forming a coating layer of an adhesive layer-forming material on the second optical element by the coating method described in any one of 1 to 7 above, and the lamination may be performed by bonding the coating layers together. 10. In the manufacturing method described in 8 or 9 above, the formation of the coating layer and the lamination may be carried out continuously. [Effects of the Invention]

[0009] According to the coating method of the embodiment of the present invention, it is possible to provide an optical laminate that can contribute to improving the visibility of an image display device. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing the general configuration of a coating unit of a gravure coating device used in a coating method according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a partially enlarged view of the coated portion shown in FIG. [Figure 3] FIG. 3 is a schematic cross-sectional view showing the general configuration of a coating unit of a gravure coating device used in a coating method according to a second embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram showing a general configuration of an example of a display system for VR goggles. [Figure 5] FIG. 2 is a schematic cross-sectional view showing an example of details of an optical laminate. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In order to clarify the description, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in the drawings, the same or equivalent elements are given the same reference numerals, and redundant explanations may be omitted.

[0012] (Definition of terms and symbols) The definitions of terms and symbols used in this specification are as follows. (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is greatest (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane retardation measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light of wavelength 550 nm at 23°C. Re(λ) is calculated by the formula: Re(λ)=(nx-ny)×d, where d (nm) is the thickness of the layer (film). (3) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light of wavelength 550 nm at 23°C. Rth(λ) is calculated by the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film). (4) Nz coefficient The Nz coefficient is calculated by Nz=Rth / Re. (5)Angle When angles are referred to herein, the angles include both clockwise and counterclockwise angles relative to a reference direction, so for example, "45°" means ±45°.

[0013] [Gravure coating equipment] FIG. 1 is a schematic cross-sectional view showing the general configuration of a coating unit of a gravure coating device used in a coating method according to a first embodiment of the present invention, and FIG. 2 is a partially enlarged view of the coating unit shown in FIG.

[0014] The coating section 6 is composed of a chamber 50, a gravure roll 60, and the like.

[0015] Chamber 50 is connected to a storage tank (not shown) that stores the coating liquid via liquid supply piping 51, and the coating liquid is supplied from the storage tank to chamber 50. The storage tank is also connected to chamber 50 via liquid return piping 52, and the coating liquid in chamber 50 can be returned to the storage tank via liquid return piping 52. In this way, during coating, the coating liquid can circulate between the storage tank and chamber 50.

[0016] The chamber 50 is disposed along the gravure roll 60. A recess (coating liquid supply portion) 50a corresponding to the gravure roll 60 is formed on the side surface of the chamber 50 (the side surface facing the gravure roll 60), and the coating liquid is supplied to the gravure roll 60 through the chamber 50.

[0017] A seal blade 53 is disposed below the recess 50a. A blade support portion 50b having a flat blade support surface is provided below the recess 50a along the lower edge of the recess 50a. A pressing tool 54 is detachably attached to the blade support portion 50b by fastening with bolts. The base end portion (attachment portion 53b) of the seal blade 53 is sandwiched between the blade support portion 50b and the pressing tool 54, thereby detachably fixing the seal blade 53 to the chamber 50.

[0018] The seal blade 53 is a strip-shaped member that closes the gap between the surface of the coating area 61 and the recess 50a. The tip side portion of the seal blade 53 (protruding portion 53a) protrudes from the blade support portion 50b toward the gravure roll 60 and comes into contact with the coating area 61.

[0019] The chamber 50 is placed next to the gravure roll 60 so that the seal blade 53 is pressed against the coating area 61. By doing so, a space (liquid reservoir) 55 in which the coating liquid is stored is formed between the gravure roll 60 and the chamber 50. During coating, the liquid reservoir 55 can be filled with the coating liquid, so that the coating area 61 facing the liquid reservoir 55 is always in contact with the coating liquid, and the coating liquid is supplied to the gravure roll 60.

[0020] The gravure roll 60 has a horizontally elongated cylindrical shape. For example, the surface of the gravure roll 60 is formed of ceramic or the like from the viewpoint of wear resistance. The diameter of the gravure roll 60 is, for example, 10 mm to 1000 mm. The gravure roll 60 is installed so as to be in contact with the surface of the sheet-like optical element S being conveyed. For example, the gravure roll 60 is supported by a frame (not shown) so as to be rotatable about a horizontal axis. The gravure roll 60 is rotated in conjunction with the conveyance of the optical element S, for example, by driving a motor (not shown), so that the outer circumferential surface rotates in the direction opposite to the conveyance direction of the optical element S at the contact portion with the optical element S. The rotation speed of the gravure roll is, for example, 10 rpm to 300 rpm, and preferably 35 rpm to 100 rpm.

[0021] A large number of depressions (cells) typically arranged in a uniform pattern are formed in the coating region 61 on the outer peripheral surface of the gravure roll 60. The coating liquid is continuously supplied from the chamber 50 to the coating region 61, which rotates as the gravure roll 60 rotates, and the coating liquid adhering to the coating region 61 can be transferred to the surface of the optical member S being transported.

[0022] Within the chamber 50 (liquid reservoir 55), the gravure roll 60 is positioned further inward than the tip (blade tip) of the protruding portion 53a of the seal blade 53 that contacts the gravure roll 60. By adopting this positional relationship, it is possible to reduce the number of air bubbles contained in the coating liquid that adheres to the coating area 61. Even if air bubbles are generated, the size of the air bubbles can be reduced. Specifically, by reducing the length (degree of protrusion) of the protruding portion 53a of the seal blade 53, it is possible to suppress the vibration of the seal blade 53 itself and thereby suppress the generation of air bubbles in the coating liquid.

[0023] The length X of the protruding portion 53a of the seal blade 53 is, for example, more than 0 mm and not more than 20 mm, and may be not more than 15 mm. The ratio Y / X of the distance Y from the contact portion 53c of the seal blade 53 and the gravure roll 60 to the tip of the protruding portion 53a of the seal blade 53 to the length X of the protruding portion 53a is, for example, more than 0 and not more than 0.5, and may be not more than 0.3, or may be not more than 0.1.

[0024] During coating, it is preferable that a space (air reservoir) 56 that is not filled with the coating liquid is formed inside the chamber 50 (liquid reservoir section 55). By forming the air reservoir 56, air bubbles generated in the coating liquid can be easily released, and the number of air bubbles contained in the coating liquid that adhere to the coating area 61 can be reduced.

[0025] 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 may be 1 cm or more. The distance between the upper surface of the coating liquid and the inner wall 50c of the chamber 50 may correspond to the height of the air reservoir 56. The ratio A / B of the volume A of the coating liquid in the liquid reservoir 55 to the volume B of the liquid reservoir 55 is, for example, 0.5 to 0.99.

[0026] The thickness of the seal blade 53 is, for example, 0.1 mm or more and 1 mm or less, and may be 0.5 mm or less.

[0027] The coating liquid contains an adhesive layer-forming material. For example, the coating liquid may be an adhesive or a pressure-sensitive adhesive. The viscosity of the coating liquid at 23°C is, for example, 25 mPa·s to 50 mPa·s, and preferably 27 mPa·s to 47 mPa·s.

[0028] 3 is a schematic cross-sectional view showing the general configuration of the coating section of a gravure coating apparatus used in a coating method according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in that the liquid reservoir section 55 is formed so that the upper end (upper inner wall 50c) of the liquid reservoir section 55 is located above the liquid supply pipe 51. This allows an air reservoir 56 to be formed within the chamber 50 without controlling the circulation of the coating liquid.

[0029] [Optical laminate] Typically, a coating layer of an adhesive layer-forming material is formed on a first optical member using the gravure coating device, and a second optical member is laminated on the first optical member via the coating layer to obtain an optical laminate. The thickness of the coating layer varies depending on the composition of the adhesive layer-forming material, but is typically 0.5 μm to 50 μm, and may be 0.5 μm to 15 μm. When laminating the first optical member and the second optical member, a coating layer of an adhesive layer-forming material may also be formed on the second optical member using the gravure coating device. In this case, the coating layer formed on the first optical member and the coating layer formed on the second optical member may be bonded together to perform lamination.

[0030] For example, from the viewpoint of production efficiency, the formation of the coating layer and lamination are carried out continuously. The coating layer coated using the gravure coating device has few bubbles, and lamination can be carried out immediately after coating.

[0031] By using the gravure coating device, for example, an optical laminate with few air bubbles can be obtained. The optical laminate can be typically applied to an image display device. By incorporating an optical laminate with few air bubbles, an image display device with excellent visibility can be realized. In an image display device, air bubbles contained in the optical laminate may affect visibility. Specifically, air bubbles contained in the optical laminate may be visually recognized as a defect. The higher the resolution of the image display device, the more strict defect management is required for the components that make up the image display device. Therefore, using an optical laminate with few air bubbles can contribute to improving the visibility of the image display device. In particular, in VR goggles, air bubbles may be enlarged and tend to be easily visually recognized as a defect, so using an optical laminate with few air bubbles can greatly contribute to improving visibility.

[0032] FIG. 4 is a schematic diagram showing the overall configuration of an example of a display system for VR goggles, illustrating the arrangement and shape of each component of the display system. The display system 2 includes a display element 12, a reflective polarizing element 14, a first lens unit 16, a half mirror 18, a first λ / 4 element 20, a second λ / 4 element 22, and a second lens unit 24. The reflective polarizing element 14 is disposed in front of the display surface 12a of the display element 12 and can reflect light emitted from the display element 12. The first lens unit 16 is disposed on the optical path between the display element 12 and the reflective polarizing element 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first λ / 4 element 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second λ / 4 element 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing element 14.

[0033] The display element 12 is, for example, a liquid crystal display or an organic EL display, and has a display surface 12a for displaying an image. The light emitted from the display surface 12a passes through, for example, a polarizing member that may be included in the display element 12, and is converted into a first linearly polarized light.

[0034] The first λ / 4 member 20 can convert the first linearly polarized light incident on the first λ / 4 member 20 into first circularly polarized light. The first λ / 4 member 20 may be provided integrally with the display element 12.

[0035] The half mirror 18 transmits the light emitted from the display element 12 and reflects the light reflected by the reflective polarizing member 14 back toward the reflective polarizing member 14. The half mirror 18 is provided integrally with the first lens portion 16.

[0036] The second λ / 4 member 22 can transmit light reflected by the reflective polarizing member 14 and the half mirror 18 through the reflective polarizing member 14. The second λ / 4 member 22 may be provided integrally with the first lens portion 16.

[0037] The first circularly polarized light output from the first λ / 4 element 20 passes through the half mirror 18 and the first lens unit 16, and is converted into the second linearly polarized light by the second λ / 4 element 22. The second linearly polarized light output from the second λ / 4 element 22 is reflected toward the half mirror 18 without passing through the reflective polarizing element 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing element 14 is the same as the reflection axis of the reflective polarizing element 14. Therefore, the second linearly polarized light incident on the reflective polarizing element 14 is reflected by the reflective polarizing element 14.

[0038] The second linearly polarized light reflected by the reflective polarizing element 14 is converted into second circularly polarized light by the second λ / 4 element 22, and the second circularly polarized light emitted from the second λ / 4 element 22 passes through the first lens unit 16 and is reflected by the half mirror 18. The second circularly polarized light reflected by the half mirror 18 passes through the first lens unit 16 and is converted into third linearly polarized light by the second λ / 4 element 22. The third linearly polarized light is transmitted through the reflective polarizing element 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing element 14 is the same as the transmission axis of the reflective polarizing element 14. Therefore, the third linearly polarized light incident on the reflective polarizing element 14 is transmitted through the reflective polarizing element 14.

[0039] The light transmitted through the reflective polarizing member 14 passes through the second lens portion 24 and enters the eye 26 of the user.

[0040] The absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14 may be disposed approximately parallel to each other or approximately perpendicular to each other. The angle formed 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° to 50°, or may be 42° to 48°, or may be approximately 45°. The angle formed 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° to 50°, or may be 42° to 48°, or may be approximately 45°.

[0041] The in-plane retardation Re(550) of the first λ / 4 component 20 is, for example, 100 nm to 190 nm, or alternatively, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ / 4 component 20 preferably exhibits inverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the first λ / 4 component 20 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0042] The in-plane retardation Re(550) of the second λ / 4 component 22 is, for example, 100 nm to 190 nm, or alternatively, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The second λ / 4 component 22 preferably exhibits inverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the second λ / 4 component 22 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0043] Although not shown, display system 10 may also include an absorptive polarizer disposed in front of reflective polarizer 14. The reflective axis of the reflective polarizer and the absorption axis of the absorptive polarizer may be disposed approximately parallel to each other.

[0044] The optical stack according to the embodiment of the present invention may include, for example, components provided in the display system. Specifically, the optical stack may include a polarizing component (e.g., a reflective polarizing component, an absorptive polarizing component), a retardation component such as a λ / 4 component, an optical component such as a protective component, and an adhesive layer for integrating adjacent components.

[0045] The adhesive layer included in the optical laminate may be a layer formed by curing or solidifying a coating layer formed by applying a coating liquid containing an adhesive layer-forming material using the gravure coating device. When the adhesive layer is an adhesive layer, its thickness is typically 0.5 μm to 5 μm. When the adhesive layer is a pressure-sensitive adhesive layer, its thickness is typically 5 μm to 50 μm. The size of bubbles that may be included in the adhesive layer is preferably less than 20 μm, more preferably less than 15 μm. Even if bubbles are included in the adhesive layer, as long as the bubbles are of this size, extremely excellent visibility can be achieved in image display devices (e.g., VR goggles). The size of the bubbles can be measured, for example, by observation using an optical microscope. In one embodiment, the proportion of bubbles 20 μm or larger in size among all bubbles included in one adhesive layer is preferably 5% or less, more preferably 1% or less.

[0046] FIG. 5 is a schematic cross-sectional view showing an example of the details of the 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 the polarizing member that may be included in the display element (display element 12). The polarizing member 12b typically includes at least an absorption-type polarizing film, and a protective layer may be laminated via an adhesive layer (not shown) on one or both sides of the absorption-type polarizing film. The optical laminate 4 includes another retardation member 32 in addition to the first λ / 4 member 20. In the illustrated example, the retardation member 32 is disposed between the first λ / 4 member 20 and the polarizing member 12b, but may be disposed, for example, between the first λ / 4 member 20 and the protective member 30. Each member is laminated via adhesive layers 41, 42, 43. Although not shown, the optical laminate 4 may further include another retardation member. For example, another retardation member may be disposed between the polarizing member 12b and the retardation member 32 via an adhesive layer. In this case, the another retardation member may also serve as the protective layer of the absorption-type polarizing film. In the above display system, the optical laminate 4 that may be provided integrally with the display element 12 requires particularly strict defect management. At least one of the adhesive layers included in the optical laminate 4 may be formed by coating a coating liquid containing an adhesive layer forming material with the gravure coating apparatus. Thus, the optical laminate 4 can clear strict defect management and achieve extremely excellent visibility in the VR goggles.

[0047] The first λ / 4 member 20 preferably exhibits a refractive index characteristic 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, ny < nz may occur. The Nz coefficient of the first λ / 4 member 20 is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0048] The first λ / 4 member 20 is made of any appropriate material that can satisfy the above characteristics. The first λ / 4 member 20 can be, for example, a stretched resin film or an oriented and solidified layer of a liquid crystal compound.

[0049] Examples of resins contained in the 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 may be used alone or in combination. Examples of methods for combining include blending and copolymerization. When the first λ / 4 member 20 exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate resin or a polyester carbonate resin (hereinafter sometimes simply referred to as a polycarbonate resin) can be suitably used.

[0050] Any suitable polycarbonate-based resin can be used as the polycarbonate-based resin. For example, the polycarbonate-based resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri-, or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate-based resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, structural units derived from an alicyclic dimethanol, and / or structural units derived from di-, tri-, or polyethylene glycol; more preferably, it contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from di-, tri-, or polyethylene glycol. The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds as needed. Details of polycarbonate resins that can be suitably used for the first λ / 4 member 20 and methods for forming the first λ / 4 member 20 are described, for example, in JP 2014-10291 A, JP 2014-26266 A, JP 2015-212816 A, JP 2015-212817 A, and JP 2015-212818 A, and the descriptions in these publications are incorporated herein by reference.

[0051] The thickness of the first λ / 4 member 20 made of a stretched resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, and more preferably 20 μm to 60 μm.

[0052] The above-mentioned alignment-solidified layer of the liquid crystal compound is a layer in which the liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. The term "alignment-solidified layer" encompasses an alignment-solidified layer obtained by curing a liquid crystal monomer, as described below. In the first λ / 4 member 20, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the first λ / 4 member 20 (homogeneous alignment). Examples of rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable. If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by aligning the liquid crystal compound and then polymerizing it.

[0053] The alignment and solidification layer of the liquid crystal compound (liquid crystal alignment and solidification layer) can be formed by performing an alignment treatment on the surface of a predetermined substrate, applying a coating liquid containing a liquid crystal compound to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the alignment state. Any appropriate alignment treatment can be used as the alignment treatment. Specific examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. Specific examples of mechanical alignment treatment include rubbing 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 oblique vapor deposition and photoalignment treatment. Any appropriate treatment conditions can be used for the various alignment treatments depending on the purpose.

[0054] The alignment of liquid crystal compounds is achieved by treating them at a temperature at which they exhibit a liquid crystal phase depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compounds assume a liquid crystal state and are aligned in accordance with the alignment treatment direction of the substrate surface.

[0055] In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is polymerizable or crosslinkable, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or crosslinking treatment.

[0056] Any suitable liquid crystal polymer and / or liquid crystal monomer can be used as the liquid crystal compound. The liquid crystal polymer and the liquid crystal monomer can be used alone or in combination. Specific examples of liquid crystal compounds and methods for producing a liquid crystal alignment solidified layer are described in, for example, JP 2006-163343 A, JP 2006-178389 A, and WO 2018 / 123551 A. The descriptions in these publications are incorporated herein by reference.

[0057] The thickness of the first λ / 4 member 20 made of the liquid crystal alignment solidified 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.

[0058] The polarizing member 12b may include, for example, a resin film containing a dichroic material (sometimes referred to as an absorptive polarizing film). The thickness of the absorptive polarizing film is, for example, 1 μm to 20 μm, or may be 2 μm to 15 μm, or may be 12 μm or less, 10 μm or less, 8 μm or less, or may be 5 μm or less.

[0059] The absorptive polarizing film may be made from a single layer of resin film or may be made from a laminate of two or more layers.

[0060] When fabricating from a single-layer resin film, an absorptive polarizing film can be obtained by dyeing a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or a partially saponified ethylene-vinyl acetate copolymer film with iodine or a dichroic substance such as a dichroic dye, stretching, etc. Among these, an absorptive polarizing film obtained by dyeing a PVA film with iodine and uniaxially stretching it is preferred.

[0061] The dyeing with iodine is 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. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the stretching may be followed by dyeing. If necessary, the PVA film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, etc.

[0062] Examples of laminates produced using the two or more layer laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. An absorptive polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; and then stretching and dyeing the laminate to convert the PVA-based resin layer into an absorptive polarizing film. In this embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. The stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, the stretching may further include, if necessary, in-air stretching of the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. Additionally, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment by heating while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an in-air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA, even when PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the subsequent dyeing and stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of an absorptive polarizing film obtained through treatment steps, such as dyeing and underwater stretching, in which the laminate is immersed in a liquid. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through drying shrinkage treatment.The obtained resin substrate / absorptive polarizing film laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the absorptive polarizing film), or any suitable protective layer may be laminated depending on the purpose on the surface obtained by peeling the resin substrate from the resin substrate / absorptive polarizing film laminate, or on the surface opposite to the peeled surface. Details of such methods for producing absorptive polarizing films are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. The entire disclosures of these publications are incorporated herein by reference.

[0063] The protective member 30 typically includes a substrate. The substrate can be made of any appropriate film. Examples of materials that form the main component of the film constituting the substrate include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cycloolefin-based resins such as polynorbornene, polyolefin-based, (meth)acrylic, and acetate-based resins. 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.

[0064] The protective member 30 may preferably have a substrate and a surface treatment layer formed on the substrate. A protective member having a surface treatment layer can be disposed so that the substrate is located on the first λ / 4 member 20 side. The surface treatment layer can have any appropriate function. For example, the surface treatment layer preferably has an anti-reflection 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.

[0065] The phase difference member 32 may have any appropriate refractive index characteristics. For example, the refractive index characteristics of the phase difference member 32 exhibit the relationship nz>nx≧ny. By using a member 32 exhibiting the relationship nz>nx≧ny, light leakage (for example, light leakage in oblique directions) can be prevented.

[0066] The retardation Rth(550) in the thickness direction of the retardation member 32, whose refractive index characteristics satisfy the relationship nz>nx≧ny, is preferably −260 nm to −10 nm, more preferably −230 nm to −15 nm, and even more preferably −215 nm to −20 nm. In one embodiment, the retardation member 32 is a so-called positive C plate, whose refractive index satisfies the relationship nx=ny. Here, “nx=ny” encompasses 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 encompasses the case where Re(550) is less than 10 nm. In another embodiment, the retardation member 32 has a refractive index satisfying the relationship nx>ny. In this case, the in-plane retardation Re(550) of the retardation member 32 is preferably 10 nm to 150 nm, and more preferably 10 nm to 80 nm.

[0067] The retardation member 32, whose refractive index characteristics satisfy the relationship nz>nx≧ny, can be formed from any appropriate material. It is preferably composed of a film containing a liquid crystal material fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and methods for forming the film include those described in

[0020] to

[0042] of JP 2002-333642 A. In this case, the thickness is preferably 0.1 μm to 5 μm, and more preferably 0.5 μm to 4 μm.

[0068] As another preferred example, the retardation member 32 having refractive index characteristics satisfying the relationship nz>nx≧ny may be a retardation film formed of a fumaric acid diester resin described in JP 2012-32784 A. In this case, the thickness is preferably 5 μm to 50 μm, and more preferably 10 μm to 35 μm.

[0069] The other retardation member has, for example, a refractive index characteristic that satisfies the relationship nx>ny>nz. The in-plane retardation Re(550) of the retardation member having a refractive index characteristic that satisfies the relationship nx>ny>nz 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. [Example]

[0070] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The thickness, in-plane retardation, and viscosity are values ​​measured by the following measurement methods. <Thickness> Thicknesses of 10 μm or less were measured using a scanning electron microscope (manufactured by JEOL Ltd., product name "JSM-7100F"), and thicknesses of more than 10 μm were measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). <In-plane phase difference Re(λ)> The film was cut from the center and both ends in the width direction to prepare square samples measuring 50 mm in width and 50 mm in length, with one side parallel to the width direction of the film. The in-plane retardation of these samples was measured at each wavelength at 23°C using a Mueller matrix polarimeter (Axometrics, product name "Axoscan"). <Viscosity> The viscosity was measured at 23°C using a dynamic viscoelasticity measuring device (TV-25 type viscometer manufactured by Toki Sangyo Co., Ltd.).

[0071] [Example 1] (Fabrication of λ / 4 components) 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 polymerization mixture contained 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10 calcium acetate monohydrate as a catalyst. -2 Part of mass (6.78×10 -5 (mol) was charged. 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. Forty minutes after the start of the temperature increase, the internal temperature reached 220°C. This temperature was maintained while simultaneously reducing the pressure. 90 minutes after reaching 220°C, the pressure was reduced to 13.3 kPa. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 100°C, and the small amount of monomer components contained in the phenol vapor was returned to the reactor. Uncondensed phenol vapor was collected by introducing nitrogen into the first reactor and temporarily restoring the pressure to atmospheric pressure. The oligomerized reaction liquid in the first reactor was then transferred to the second reactor. Next, heating and depressurization of the second reactor were initiated, and the internal temperature reached 240°C and the pressure reached 0.2 kPa in 50 minutes. The polymerization was then allowed to proceed until the specified stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the polyester carbonate resin produced was extruded into water, and the strands were cut to obtain pellets.

[0072] The resulting polyester carbonate resin pellets were vacuum-dried at 80°C for 5 hours and then used in a film-making machine equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder temperature setting: 250°C), a T-die (width: 200 mm, temperature setting: 250°C), a chill roll (temperature setting: 120-130°C), and a winder to produce a 135 μm-thick long resin film. The resulting long resin film was stretched in the width direction at a stretching temperature of 143°C and a stretch ratio of 2.8 to obtain a 47 μm-thick stretched film. The resulting stretched film had an Re(550) of 143 nm, an Re(450) / Re(550) of 0.86, and an Nz coefficient of 1.12.

[0073] (Preparation of adhesive) An adhesive with a viscosity of 27 to 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 Kyoeisha 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's trade name "KAYACURE DETX-S" for 60 minutes.

[0074] (Preparation of coating layer) The adhesive was applied to the λ / 4 member (stretched film) using the gravure coating device shown in Figure 1 so as to form a coating layer with a thickness of 1.5 to 2.5 µm after curing. For coating, a seal blade 53 with a thickness of 0.2 mm and a length X of the protruding portion 53a of the seal blade 53 shown in Figure 2 was used. The distance Y from the contact portion 53c between the seal blade 53 and the gravure roll 60 to the tip of the protruding portion 53a of the seal blade 53 was 5 mm.

[0075] [Comparative Example 1] When applying the adhesive, a coating layer was formed on a λ / 4 member in the same manner as in Example 1, except that the length X of the protruding portion 53a of the seal blade was set to 24 mm and a seal blade having a thickness of 0.3 mm was used, as shown in Figure 2. The distance Y from the contact portion 53c between the seal blade 53 and the gravure roll 60 to the tip of the protruding portion 53a of the seal blade 53 was 14 mm.

[0076] The number of bubbles in the coating layers obtained in Example 1 and Comparative Example 1 was counted by observation with an optical microscope. The evaluation results are shown in Table 1.

[0077] [Table 1]

[0078] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations shown in the above-described embodiment can be replaced with configurations that are substantially the same as those shown in the above-described embodiment, that have the same effects, or that can achieve the same purpose. [Industrial Applicability]

[0079] The coating method according to an embodiment of the present invention is used to produce an optical laminate that can be suitably used in image display devices such as VR goggles, for example. [Explanation of symbols]

[0080] 2 display system, 4 optical laminate, 6 coating section, 12 display element, 14 reflective polarizing member, 16 first lens section, 18 half mirror, 20 first λ / 4 member, 22 second λ / 4 member, 24 second lens section, 30 protective member, 32 retardation member, 41 adhesive layer, 42 adhesive layer, 43 adhesive layer, 50 chamber, 50a recess, 50b blade support section, 50c inner wall, 51 liquid supply piping, 52 liquid return piping, 53 seal blade, 53a protrusion, 53b mounting section, 54 pressing tool, 55 liquid reservoir section, 56 air reservoir, 60 gravure roll, 61 coating area.

Claims

1. A method for applying a coating liquid containing an adhesive layer-forming material to a sheet-like optical member that is continuously conveyed using a gravure coating device, comprising: The gravure coating device is a gravure roll having a coating area on its outer circumferential surface to which the coating liquid is applied, the gravure roll rotating in conjunction with the conveyance of the optical element; a chamber having a coating liquid supply unit on a side thereof for supplying the coating liquid to the rotating coating area; a seal blade that closes a gap between the coating liquid supply unit and the surface of the coating area, the seal blade has a protruding portion that protrudes toward the inside of the chamber and contacts the coating area, In the chamber, the gravure roll is located inside the tip of the protruding portion of the seal blade, a ratio Y / X of a distance Y from a contact portion between the seal blade and the gravure roll to a tip of the protrusion of the seal blade to a length X of the protrusion is 0.5 or less; Coating method.

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

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

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

99.

5. the seal blade has an attachment portion that is detachably fixed to a blade support portion that is disposed in the vicinity of the gravure roll, and a protrusion portion that protrudes from the blade support portion toward the gravure roll and comes into contact with the coating area, The coating method according to claim 1, wherein the length of the protrusion is 20 mm or less.

6. 2. The coating method according to claim 1, wherein the rotation speed of the gravure roll is 10 rpm to 300 rpm.

7. Forming a coating layer of an adhesive layer-forming material on a first optical member; laminating a second optical member on the first optical member via the coating layer; Including, forming the coating layer includes forming the coating layer by a method of applying a coating liquid containing an adhesive layer-forming material to the sheet-like first optical member that is continuously conveyed using a gravure coating device; The gravure coating device is a gravure roll having a coating area on its outer circumferential surface to which the coating liquid is applied, the gravure roll rotating in conjunction with the conveyance of the optical element; a chamber having a coating liquid supply unit on a side thereof for supplying the coating liquid to the rotating coating area; a seal blade that closes a gap between the coating liquid supply unit and the surface of the coating area, the seal blade has a protruding portion that protrudes toward the inside of the chamber and contacts the coating area, A method for manufacturing an optical laminate, wherein, in the chamber, the gravure roll is positioned inside the tip of the protruding portion of the seal blade.

8. The method further includes forming a coating layer of an adhesive layer-forming material on the second optical member, and laminating the coating layers by bonding them together, The method for manufacturing an optical laminate described in claim 7, wherein forming the coating layer includes forming the coating layer by applying a coating liquid containing the adhesive layer forming material to the sheet-like second optical element that is continuously transported using the gravure coating device.

9. The method for producing an optical laminate according to claim 7 , wherein the formation of the coating layer and the lamination are carried out continuously.

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