Method for manufacturing a light guide plate for image display

Abstract

To provide a light guide plate for image display with excellent clarity.SOLUTION: A light guide plate 8 for image display includes a first resin base material 1, a first barrier layer 3, and a hologram layer 4 that are arranged in this order. The specular glossiness at the incident angle of 60 degrees of a side of a first laminated body 11 including the first resin base material 1 and the first barrier layer 3, which is in contact with the hologram layer 4, is 120% or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light guide plate for image display. Manufacturing method Regarding. [Background technology]

[0002] In some display devices, a light guide plate for image display is used. For example, in a display device using VR (Virtual Reality) technology or AR (Augmented Reality) technology, a light guide plate for image display in which a hologram layer is supported on a transparent substrate is used. In the hologram layer, a hologram having various optical functions, such as wave guidance, reflection, and diffraction, is formed. Many of the materials used for the hologram layer are photosensitive compositions containing radical polymerizable monomers, polyacids, or bases such as amines, and the like, which may deteriorate the resin substrate. In particular, when the resin substrate is gradually corroded over a long period of time and deteriorated, the visibility of the light guide plate is likely to decrease.

[0003] Patent Document 1 describes forming a photosensitive material layer for forming a hologram on an optically transparent resin substrate, and covering the photosensitive material layer with an aqueous polymer protective barrier. Patent Document 1 suggests that the aqueous polymer protective barrier is provided for the purpose of resisting attack by moisture. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-181400 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, it is considered to provide a barrier layer between the substrate and the hologram layer for the purpose of protecting the hologram layer from water vapor, etc. However, this may result in a decrease in clarity of the light guide plate.

[0006] An object of the present invention is to provide a light guide plate for image display having good clarity. [Means for solving the problem]

[0007] Means for Solving the Problems The present inventors have conducted extensive research to achieve the above object, and have found that there is a correlation between the clarity and specular gloss of a light guide plate for image display, thereby completing the present invention. That is, the present invention has the following aspects.

[0008] [1] A light-guiding plate for image display, comprising a first resin substrate, a first barrier layer, and a hologram layer arranged in this order, and wherein a specular gloss at an incident angle of 60 degrees on a side of a first laminate including the first resin substrate and the first barrier layer that contacts the hologram layer is 120% or more. [2] The light guide plate for image display according to [1], wherein the first resin substrate contains at least one resin selected from the group consisting of poly(meth)acrylic resins, epoxy resins, cyclic polyolefin resins, and polycarbonate resins. [3] The light guide plate for image display according to [1] or [2], wherein the first barrier layer contains an inorganic material. [4] The light guide plate for image display according to [3], wherein the inorganic material is at least one selected from the group consisting of silicon oxide, silicon nitroxide, diamond-like carbon, aluminum oxide and glass. [5] The light-guiding plate for image display according to any one of [1] to [4], wherein the first laminate has a first anchor coat layer between the first resin substrate and the first barrier layer. [6] The light guide plate for image display according to [5], wherein the first anchor coat layer contains at least one resin selected from the group consisting of an acrylic resin, a urethane resin, and a polyester resin. Effect of the Invention

[0009] According to the present invention, a light guide plate for image display having good clarity can be provided. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing an example of a light guide plate for image display of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described. However, the present invention is not limited to the embodiment described below, and various modifications are possible without departing from the gist of the present invention.

[0012] "UV" stands for ultraviolet. "(Meth)acrylic" means one or both of acrylic and methacrylic. "(Meth)acrylate" means one or both of acrylate and methacrylate.

[0013] <Light guide plate for image display> The light guide plate for image display of this embodiment has at least a first resin substrate, a first barrier layer, and a hologram layer. The first resin substrate, the first barrier layer, and the hologram layer are arranged in this order in the thickness direction. The first resin substrate and the first barrier layer may be arranged on at least one surface of the hologram layer, but may be arranged on both surfaces of the hologram layer. When the first resin substrate and the first barrier layer are arranged on both surfaces of the hologram layer, the first resin substrate and the first barrier layer arranged on one surface of the hologram layer are respectively referred to as the first resin substrate and the first barrier layer, and the first resin substrate and the second barrier layer arranged on the other surface of the hologram layer are respectively referred to as the second resin substrate and the second barrier layer. In this case, the hologram layer is sandwiched between the first barrier layer and the second barrier layer, the first resin substrate is laminated on the other surface of the first barrier layer, and the second resin substrate is laminated on the other surface of the second barrier layer. In this embodiment, the first resin substrate and the second resin substrate may be collectively referred to simply as "resin substrate" below. Furthermore, hereinafter, the first barrier layer and the second barrier layer may be collectively referred to simply as "barrier layer".

[0014] One or more transparent layers may be disposed between the first resin substrate and the first barrier layer, and between the first barrier layer and the hologram layer. Examples of the transparent layer include an anchor coat layer and a hard coat layer. From the viewpoint of improving the adhesion between the first resin substrate and the first barrier layer, it is preferable to provide a first anchor coat layer between the first resin substrate and the first barrier layer, that is, it is preferable to arrange the first resin substrate, the first anchor coat layer, the first barrier layer, and the hologram layer in this order.

[0015] The light guide plate for image display has an incident section for receiving image light and a display section for displaying an image based on the image light. The hologram layer is disposed between the incident section and the display section. The hologram layer has a diffraction grating pattern formed thereon for guiding at least the image light incident from the incident section to the display section and emitting the image light from the display section. The diffraction grating pattern in the display section transmits at least a portion of external light incident from outside the light guide plate for image display. The external light is incident from the surface opposite to the display section.

[0016] The image light incident on the incident portion is guided in the hologram layer and is emitted to the outside from the display portion. Meanwhile, external light also passes through the resin base material and the display portion, so that a viewer of the display portion can observe both the image light and external light within the field of view. The light guide plate for image display of this embodiment is suitable for use in display devices using VR (virtual reality) technology or AR (augmented reality) technology. Furthermore, the light guide plate for image display of this embodiment may be used in devices such as a combiner for a head-up display (HUD) mounted on an automobile, or a holographic optical element (HOE) such as a reflector for a reflective liquid crystal display device, in addition to display applications.

[0017] Hereinafter, a detailed configuration of an example of the light guide plate for image display of this embodiment will be described based on the example shown in Fig. 1. Fig. 1 is a schematic cross-sectional view showing an example of the light guide plate for image display of the embodiment of the present invention.

[0018] In the light guide plate 8 for image display shown in Figure 1, a first laminate 11 having a first resin substrate 1, a first anchor coat layer 2 and a first barrier layer 3, and a second laminate 12 having a hologram layer 4, a second barrier layer 5, a second anchor coat layer 6 and a second resin substrate 7 are arranged in this order in the thickness direction. There is no particular limitation on the planar shape of the image display light guide plate 8. For example, the image display light guide plate 8 may be shaped so as to be attachable to a display device in which it is used. For example, the light guide plate 8 for image display may be a rectangular plate larger than the shape to be attached to the display device. In this case, the light guide plate 8 for image display is cut or otherwise shaped into a shape that can be attached to the display device before being assembled into the display device. The image display light guide plate 8 may be in the form of a flat plate, or may be in the form of a curved plate as required. In the following, an example will be described in which the image display light guide plate 8 is made of a flat plate that is rectangular in plan view.

[0019] <First laminate 11> The first laminate 11 has a first resin base material 1, a first anchor coat layer 2, and a first barrier layer 3. Note that if the adhesion between the first resin base material 1 and the first barrier layer 3 is good, the first anchor coat layer 2 is not essential.

[0020] The first laminate 11 transmits image light emitted from the hologram layer 4 and external light that transmits through the second laminate 12 and the hologram layer 4, which will be described later. The inventors have discovered that by increasing the specular gloss of the first laminate 11, optical defects in the first laminate 11 are reduced and factors that cause light diffusion are reduced, thereby improving the clarity of the light-guiding plate 8 for image display. From the viewpoint of improving the clarity of the light guide plate 8 for image display, the specular gloss at an incident angle of 60 degrees on the side of the first laminate 11 in contact with the hologram layer 4 is 120% or more, preferably 130% or more, more preferably 140% or more, and even more preferably 150% or more. In the present invention, the specular glossiness is a value measured in accordance with JIS Z 8741:1997 when the incident angle of the light source is 60 degrees.

[0021] The total light transmittance of the first laminate 11 is not particularly limited, but is preferably 80% or more, and more preferably 90% or more. If the total light transmittance is 80% or more, the clarity and brightness of the light guide plate for image display 8 will be better.

[0022] The transmission b* value of the first laminate 11 in the CIE1976 L*a*b* color space defined in JIS Z 8781-4:2013 is not particularly limited, but is preferably 0.90 or less, more preferably 0.50 or less, even more preferably 0.40 or less, and even more preferably 0.30 or less.

[0023] The refractive index of the first laminate 11 is not particularly limited, but is preferably 1.48 or more. If the refractive index of the first laminate 11 is 1.48 or more, the viewing angle can be further increased when used as a light guide plate for image display. The upper limit of the refractive index of the first laminate 11 is not particularly limited, but is usually 3.00 or less. The refractive index in the present invention can be measured, for example, by a refractive index measuring device (Model 2010 / M Prism Coupler, manufactured by Metricon).

[0024] The surface roughness Sa of the first laminate 11 on the side in contact with the hologram layer 4 is not particularly limited, but is preferably 5 nm or less, more preferably 3 nm or less, even more preferably 2 nm or less, and still more preferably 1.5 nm or less. The smaller the surface roughness Sa of the first laminate 11 on the side in contact with the hologram layer 4, the more light diffusion due to surface irregularities can be suppressed, and the more the clarity of the image can be improved. In the present invention, the surface roughness Sa is a surface roughness measured using a white light interferometer (VertScan, manufactured by Ryoka Systems Co., Ltd.).

[0025] The pencil hardness of the surface of the first laminate 11 not in contact with the hologram layer 4 is not particularly limited, but is preferably 3H or more, more preferably 4H or more, and even more preferably 5H or more. The higher the pencil hardness of the surface of the first laminate 11 not in contact with the hologram layer 4, the better the scratch resistance of the light guide plate 8 for image display can be imparted.

[0026] The parallelism of the first laminate 11 at 50 mm×100 mm is not particularly limited, but is preferably 0.01 to 5 μm. As the parallelism increases, the reflection angle of light becomes more unstable, and the wavelength dependency of luminance increases, causing problems such as changes in image contrast and reduced image clarity. If the parallelism is within the above range, the reduction in image clarity caused by changes in image contrast can be further suppressed. The parallelism is evaluated by measurement using a Fizeau interferometer (laser interferometer).

[0027] From the viewpoint of preventing deterioration of the hologram layer 4, the first laminate 11 preferably has at least one of oxygen barrier property and water vapor barrier property, and more preferably has both. The oxygen permeability of the first laminate 11 is not particularly limited, but is preferably 1 cm 3 / m 2 / day / atm or less is preferred. The water vapor transmission rate of the first laminate 11 at 40°C and 90% is 1 g / m 2 / day or less is preferable, and 0.5g / m 2 / day or less is more preferable, and 0.1g / m 2 / day or less is even more preferable.

[0028] [First resin base material 1] The first resin base material 1 is disposed at the outermost part in the thickness direction of the light guide plate for image display 8. The first resin base material 1 is disposed on the surface of the light guide plate for image display 8 on the display image output side. The first resin base material 1 has the same external shape as the light guide plate 8 for image display.

[0029] The thickness of the first resin base material 1 is not particularly limited, and may be, for example, 0.05 to 10 mm. To obtain good scratch resistance, the first resin base material 1 has a thickness of preferably 0.05 mm or more, more preferably 0.1 mm or more, and more preferably 0.2 mm or more. From the viewpoint of improving moldability and total light transmittance, the thickness of the first resin base material 1 is preferably 10 mm or less, more preferably 5 mm or less, further preferably 3 mm or less, and even more preferably 2 mm or less. In this specification, the thickness of the first resin base material 1 can be measured by a dial gauge using a stylus, a micrometer, or the like.

[0030] The total light transmittance of the first resin base material 1 is not particularly limited, but is preferably 80% or more, and more preferably 90% or more. The higher the total light transmittance, the better the luminance value of the light guide plate 8 for image display.

[0031] The surface roughness Sa of the first resin base material 1 is not particularly limited, but is preferably 10 nm or less, and more preferably 5 nm or less. The smaller the surface roughness Sa, the smaller the surface roughness Sa of the first laminate 11 can be, and the better the luminance value of the light guide plate for image display 8.

[0032] The specular gloss of the first resin base material 1 is not particularly limited, but is preferably 120% or more, and more preferably 130% or more. The higher the specular gloss, the higher the specular gloss of the first laminate 11 can be, and the better the luminance value of the light guide plate for image display 8.

[0033] The transmission b* value of the first resin substrate 1 in the CIE1976 L*a*b* color space defined in JIS Z 8781-4:2013 is not particularly limited, but is preferably 0.50 or less, and more preferably 0.40 or less. The smaller the transmission b* value, the smaller the transmission b* value of the first laminate 11 can be.

[0034] The first resin base material 1 preferably contains a thermoplastic resin from the viewpoint of improving optical properties, impact resistance, scratch resistance, and moldability. Examples of thermoplastic resins include polyolefin-based resins such as homopolymers or copolymers of ethylene, propylene, butene, etc.; amorphous polyolefin-based resins such as cyclic polyolefin resins; polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); cellulose-based resins such as triacetyl cellulose, diacetyl cellulose, and cellophane; polyamide-based resins such as nylon 6, nylon 66, nylon 12, and copolymer nylon; ethylene-vinyl acetate copolymer partial hydrolyzate (EVOH), polyimide-based resins, polyetherimide-based resins, polysulfone-based resins, and polyether Examples of the thermoplastic resin include organic materials such as teresulfone resin, polyether ether ketone resin, polycarbonate resin, polyvinyl butyral resin, polyarylate resin, fluororesin, poly(meth)acrylic resin, styrene resin such as polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyvinyl chloride, cellulose, acetyl cellulose, polyvinylidene chloride, polyphenylene sulfide, polyurethane, phenol resin, epoxy resin, polynorbornene, styrene-isobutylene-styrene block copolymer (SIBS), allyl diglycol carbonate, and biodegradable resin. These thermoplastic resins can be used alone or in combination of two or more. The first resin substrate 1 may also be configured by laminating layers made of two or more materials selected from the group consisting of the above thermoplastic resins. In the present invention, from the viewpoint of transparency, at least one selected from the group consisting of poly(meth)acrylic resins, epoxy resins, cyclic polyolefin resins, and polycarbonate resins is preferred, and from the viewpoint of excellent scratch resistance and moldability, poly(meth)acrylic resins are more preferred.

[0035] (Poly(meth)acrylic resin) Examples of monomers constituting the poly(meth)acrylic resin include methyl methacrylate, methacrylic acid, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and norbornyl (meth)acrylate. acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, acrylic (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc. These may be used by polymerizing alone, or two or more of them may be polymerized and used.

[0036] In addition, other monomers copolymerizable with the monomers constituting the poly(meth)acrylic resin may be added. The other monomers may be monofunctional monomers, i.e., compounds having one polymerizable carbon-carbon double bond in the molecule, or polyfunctional monomers, i.e., compounds having at least two polymerizable carbon-carbon double bonds in the molecule. Examples of monofunctional monomers include aromatic alkenyl compounds such as styrene, α-methylstyrene, and vinyltoluene; alkenyl cyanide compounds such as acrylonitrile and methacrylonitrile; acrylic acid, methacrylic acid, maleic anhydride, and N-substituted maleimides. Examples of polyfunctional monomers include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate, and trimethylolpropane triacrylate; alkenyl esters of unsaturated carboxylic acids such as allyl acrylate, allyl methacrylate, and allyl cinnamate; polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate, triallyl cyanurate, and triallyl isocyanurate; and aromatic polyalkenyl compounds such as divinylbenzene. The monofunctional monomers and polyfunctional monomers can be used alone or in combination of two or more.

[0037] The poly(meth)acrylic resin can be produced by polymerizing the above-mentioned monomer components by a known method such as suspension polymerization, emulsion polymerization, or bulk polymerization.

[0038] [First anchor coat layer 2] From the viewpoint of improving the adhesion between the first resin base material 1 and the first barrier layer 3 , it is preferable to provide a first anchor coat layer 2 between the first resin base material 1 and the first barrier layer 3 .

[0039] The material of the first anchor coat layer 2 is not particularly limited, but examples thereof include a thermoplastic resin or a curable resin. Examples of the thermoplastic resin include fluorine-based resins, polyethersulfone-based resins, polycarbonate-based resins, acrylic-based resins, silicone-based resins, cycloolefin-based resins, thermoplastic polyimide-based resins, polyamide-based resins, polyamideimide-based resins, polyarylate-based resins, polysulfone-based resins, polyetherimide-based resins, polyetheretherketone-based resins, polyethersilicon-based resins, polyester-based resins, and polyphenylene sulfide-based resins. Examples of the curable resin include acrylic resin, urethane resin, epoxy resin, and silicone resin. From the viewpoint of water vapor barrier properties, the material of the first anchor coat layer 2 is preferably an acrylic resin as a thermoplastic resin. Also, from the viewpoint of improving the specular gloss of the first laminate 11, the material of the first anchor coat layer 2 is preferably a urethane resin or a polyester resin.

[0040] In addition, additives such as a silane coupling agent, a sensitizer, a crosslinking agent, an ultraviolet absorber, a polymerization inhibitor, a surfactant, a filler, a release agent, and a thermoplastic resin may be added to the resin composition constituting the first anchor coat layer 2. These additives may be used alone or in combination of two or more.

[0041] The total light transmittance of the first anchor coat layer 2 is not particularly limited, but is preferably 80% or more, and more preferably 90% or more. If the total light transmittance of the first anchor coat layer 2 is 80% or more, the luminance value of the light guide plate for image display 8 becomes good.

[0042] Furthermore, when the average refractive index of the first resin substrate 1 and the first barrier layer 3 is n1, the refractive index n2 of the first anchor coat layer 2 is preferably within the range of n1±0.20, more preferably within the range of n1±0.15, and even more preferably within the range of n1±0.10. If the refractive index n2 of the first anchor coat layer 2 is within the range of n1±0.20, the luminance value of the light guide plate for image display 8 will be good and color unevenness can be prevented.

[0043] The thickness of the first anchor coat layer 2 is not particularly limited, and may be, for example, 5 to 500 nm. From the viewpoint of improving the adhesive strength between the first resin substrate 1 and the first barrier layer 3, the thickness of the first anchor coat layer 2 is preferably 5 nm or more, and more preferably 10 nm or more. From the viewpoint of suppressing color unevenness in the light guide plate for image display 8, the thickness of the first anchor coat layer 2 is preferably 500 nm or less, and more preferably 200 nm or less.

[0044] The first anchor coat layer 2 can be formed, for example, by applying a resin composition for forming the first anchor coat layer 2 to the first resin substrate 1, drying the composition in a drying chamber at about 30 to 120° C., placing the first barrier layer 3 thereon, and treating the laminate with a method such as pressing, nip rolling, or heat lamination. When the first anchor coat layer 2 is made of a curable resin, the formation of the first anchor coat layer 2 may include a curing step.

[0045] [First barrier layer 3] The first barrier layer 3 is disposed between the first resin substrate 1 and a hologram layer 4 described later. In the configuration shown in Fig. 1, the first barrier layer 3 is in close contact with the surfaces of the first anchor coat layer 2 and the hologram layer 4.

[0046] The first barrier layer 3 prevents gases such as water vapor and oxygen, which permeate from the outside of the light guide plate for image display 8 and from the first resin base material 1, from permeating into the hologram layer 4 and causing deterioration. Therefore, the first barrier layer 3 preferably has at least one of an oxygen barrier property and a water vapor barrier property, and more preferably has both. The oxygen permeability of the first barrier layer 3 is not particularly limited, but is preferably 1 cm 3 / m 2 The water vapor transmission rate of the first barrier layer 3 at 40° C. and 90% is preferably 1 g / m 2 / day or less is preferable, and 0.5g / m 2 / day or less is more preferable. Here, the oxygen permeability can be measured, for example, using an oxygen permeability measuring device (OX-TRAN 2 / 21, manufactured by MOCON). The water vapor transmission rate is measured using a water vapor transmission rate measuring device (DELTAPERM, manufactured by Technolox).

[0047] The first barrier layer 3 preferably has a higher refractive index than the first resin base material 1. For example, when an acrylic resin is used as the first resin base material 1, the refractive index of the first barrier layer 3 is preferably 1.48 or more, more preferably 1.48 to 3.0. If the first barrier layer 3 has a higher refractive index than the first resin base material 1, the light passing through the first barrier layer 3 and transmitting through the first resin base material 1 will be incident from the optically dense first barrier layer 3 to the optically coarse first resin base material 1, and the exit angle of the light from the first barrier layer 3 toward the first resin base material 1 will be increased according to the difference in refractive index between the first barrier layer 3 and the first resin base material 1. This makes it possible to widen the FOV (Field of View) in the light guide plate 8 for image display.

[0048] The first barrier layer 3 preferably contains an inorganic material. Examples of the inorganic material include silicon oxide, silicon nitrogen oxide, diamond-like carbon (DLC), aluminum oxide, and glass. These inorganic materials may be used alone or in combination of two or more. From the viewpoint of improving the specular gloss and barrier properties of the first laminate 11, the first barrier layer 3 preferably contains one or more selected from the group consisting of silicon oxide and silicon nitrogen oxide, and more preferably contains silicon oxide.

[0049] When the first barrier layer 3 is made of silicon oxide or silicon nitroxide, the thickness of the first barrier layer 3 is not particularly limited, and may be, for example, 10 to 300 nm. In order to improve the barrier property of the first barrier layer 3, the thickness of the first barrier layer 3 is preferably 10 nm or more, and more preferably 20 nm or more. From the viewpoint of improving the formability of the first barrier layer 3, the thickness of the first barrier layer 3 is preferably 300 nm or less, and more preferably 200 nm or less.

[0050] The method for forming the first barrier layer 3 using silicon oxide or silicon nitrogen oxide is not particularly limited. For example, the first barrier layer 3 can be formed by a conventionally known method such as a vacuum deposition method, a sputtering method, an ion plating method, or a plasma CVD method. When the first barrier layer 3 is formed using silicon oxide or silicon nitrogen oxide, in order to improve the adhesion between the film-forming surface (the surface of the first resin substrate 1 (the surface of the first anchor coat layer 2 in the case where the first anchor coat layer 2 is provided)) and the silicon oxide or silicon nitrogen oxide, the film-forming surface may be subjected to a surface treatment such as a corona discharge treatment or a low-temperature plasma treatment, a silane coupling agent, or a mixture of a saturated polyester and an isocyanate. For example, when forming a thin film of silicon oxide or silicon nitroxide by vacuum deposition, silicon, silicon monoxide, silicon dioxide, silicon nitroxide or a mixture thereof is used as the evaporation material, and the concentration of the evaporation material is 1.0×10 -3 ~2.0×10 -1 Under a vacuum of 10 Pa, the material is heated and evaporated using an electron beam, resistance heating, or high-frequency heating method. Also, a reactive deposition method can be adopted in which the deposition is carried out while supplying oxygen gas or nitrogen gas. In addition, for example, when forming a film by a sputtering method, silicon, silicon monoxide, silicon dioxide, silicon nitroxide, or a mixture thereof is used as a target, and the concentration of the target is 1.0×10 -2 ~5.0×10 -1 Film formation can be performed under a vacuum of 10 Pa. Alternatively, a reactive sputtering method can be used in which oxygen gas, nitrogen gas, or argon gas is supplied. When forming a film by a reactive sputtering method, the total gas flow rate is preferably 150 sccm or less, more preferably 120 sccm or less, and even more preferably 90 sccm or less. If the total gas flow rate is within the above range, the specular gloss at an incident angle of 60 degrees on the side of the first laminate 11 that contacts the hologram layer 4 can be made higher.

[0051] Diamond-like carbon (DLC) is an amorphous carbon material that generally consists of a ternary structure consisting of a diamond-like structure, a graphite-like structure, and a polyethylene-like polymer structure that contains hydrogen atoms. When a hydrocarbon such as ethylene, acetylene, or benzene is used as a carbon source to generate DLC, the structure is usually basically a ternary structure containing hydrogen. DLC has excellent hardness, lubricity, abrasion resistance, chemical stability, heat resistance, and surface smoothness. Because DLC forms the dense polymer structure described above, it also has excellent gas barrier properties and water vapor barrier properties.

[0052] When the first barrier layer 3 is formed by DLC, the formation method is not particularly limited. As a coating method for DLC, for example, a physical vapor deposition method such as a plasma CVD method, an ion plating method, or an ion beam sputtering method, or a known appropriate coating method can be used.

[0053] When the first barrier layer 3 is made of aluminum oxide, the first barrier layer 3 is, for example, Al 2 O 3 It may be formed only of Al, AlO and Al 2 O 3 It may be formed by mixing two or more kinds selected from the group consisting of: When the first barrier layer 3 is made of an aluminum oxide layer, the thickness of the first barrier layer 3 may be appropriately set according to the barrier performance required, and is not particularly limited, and may be, for example, 5 to 800 nm.

[0054] There is no particular limitation on the method for forming the first barrier layer 3 from aluminum oxide. For example, the first barrier layer 3 may be formed by a PVD method (physical vapor deposition method) such as a vacuum deposition method, a sputtering method, or an ion plating method, or a CVD method (chemical vapor deposition method). For example, in the vacuum deposition method, Al, Al 2 O 3The deposition source may be heated by resistance heating, high-frequency induction heating, electron beam heating, or the like. In the vacuum deposition method, oxygen, nitrogen, water vapor, or the like may be introduced as a reactive gas, or reactive deposition using ozone addition or ion assist may be used. Furthermore, a bias may be applied to the deposition surface, or the temperature of the deposition surface may be increased or cooled. The same applies to other deposition methods such as PVD and CVD other than sputtering and other vacuum deposition methods.

[0055] When the first barrier layer 3 is made of glass, examples of the material for the first barrier layer 3 include borosilicate glass, non-alkali glass, low-alkali glass, soda-lime glass, sol-gel glass, and these glasses that have been subjected to a heat treatment or surface treatment. As the glass, non-alkali glass is preferable from the viewpoint of avoiding coloration due to impurities.

[0056] When the first barrier layer 3 is made of glass, the thickness of the first barrier layer 3 is not particularly limited, but may be, for example, 10 to 200 μm. When the thickness of the first barrier layer 3 is 10 μm or more, the layer tends to have excellent mechanical strength and gas barrier properties. The thickness of the first barrier layer 3 is preferably 10 μm or more, and more preferably 30 μm or more. Furthermore, when the thickness of the first barrier layer 3 is 200 μm or less, the optical properties as a light guide plate, such as light transmittance, tend to be excellent. The thickness of the first barrier layer 3 is preferably 200 μm or less, more preferably 100 μm or less, even more preferably 75 μm or less, and even more preferably 50 μm or less.

[0057] When the first barrier layer 3 is made of glass, the method for forming the first barrier layer 3 can be appropriately selected, and for example, the slot downdraw method, the fusion method, or the float method can be adopted. The glass used may be a commercially available glass as it is, or may be polished to a desired thickness. Examples of commercially available glass include EAGLE2000 (manufactured by Corning), AN100 (manufactured by AGC), OA10G (manufactured by Nippon Electric Glass Co., Ltd.), and D263 (manufactured by Schott). When the first barrier layer 3 is made of glass, it may be formed on the outer surface side of the first resin base material 1 , that is, on the side opposite to the hologram layer 4 .

[0058] [Holographic layer 4] The hologram layer 4 is laminated on the surface of the first barrier layer 3 opposite to the surface facing the first resin base material 1. The configuration of the hologram layer 4 is not particularly limited. In the hologram layer 4, an appropriate diffraction grating corresponding to the function required for the light guide plate 8 for image display is formed.

[0059] The material of the hologram layer 4 is not particularly limited, and any known resin material for forming a hologram can be used. Examples of materials for the hologram layer 4 include hologram recording materials consisting of a thermosetting resin having at least one solvent-soluble, cationic polymerizable ethylene oxide ring in its structural unit, and a radically polymerizable ethylenic monomer (see JP-A-9-62169, JP-A-11-161141, and JP-A-2002-310932). Specifically, the hologram layer 4 is preferably formed from a photosensitive material including an epoxy resin such as a bisphenol-based epoxy resin; a (meth)acrylate such as triethylene glycol diacrylate; a photopolymerization initiator such as 4,4'-bis(tert-butylphenyl)iodonium hexafluorophosphate; a wavelength sensitizer such as 3,3'-carbonylbis(7-diethylamino)coumarin; and an organic solvent such as 2-butanone.

[0060] <Second laminate 12> The second laminate 12 has a second barrier layer 5, a second anchor coat layer 6, and a second resin substrate 7. Note that if the adhesion between the second barrier layer 5 and the second resin substrate 7 is good, the second anchor coat layer 6 is not essential.

[0061] [Second barrier layer 5] The second barrier layer 5 is laminated on the opposite side of the first barrier layer 3 with the hologram layer 4 interposed therebetween. The second barrier layer 5 has a structure similar to that exemplified in the description of the first barrier layer 3. However, the thickness, material, etc. of the second barrier layer 5 may be different from those of the first barrier layer 3.

[0062] [Second anchor coat layer 6] From the viewpoint of improving the adhesion between the second barrier layer 5 and the second resin substrate 7, it is preferable to provide a second anchor coat layer 6 between the second barrier layer 5 and the second resin substrate 7. Note that, if the adhesion between the second barrier layer 5 and the second resin substrate 7 is good, the second anchor coat layer 6 is not essential. As the second anchor coat layer 6, a configuration similar to that exemplified in the description of the first anchor coat layer 2 is used. However, the thickness, material, etc. of the second anchor coat layer 6 may be different from those of the first anchor coat layer 2.

[0063] [Second resin base material 7] The second resin base material 7 is laminated on the surface of the second barrier layer 5 with or without the second anchor coat layer 6. The second resin base material 7 has a structure similar to that exemplified in the description of the first resin base material 1. However, the thickness, material, etc. of the second resin base material 7 may be different from those of the first resin base material 1. In particular, since the second resin base material 7 is disposed on the surface of the external light incident side located opposite to the display image output side of the light guide plate 8 for image display, a material having a higher surface hardness than the first resin base material 1 may be used.

[0064] ≪Light guide plate for image display 8≫ In the light guide plate 8 for image display, a first barrier layer 3 and a second barrier layer 5 are disposed between the first resin base material 1 and the hologram layer 4, and between the second resin base material 7 and the hologram layer 4, respectively. The chemical resistance of the first resin base material 1 and the second resin base material 7 is much lower than that of glass, although the degree varies depending on the type of resin material, and therefore the first resin base material 1 and the second resin base material 7 have lower solvent resistance and hologram material resistance than glass. When the first resin base material 1 and the second resin base material 7 are in contact with the hologram layer 4, the hologram agent, which is a component of the hologram layer 4, is likely to pass through the first resin base material 1 and the second resin base material 7, and the hologram agent is likely to accumulate inside the first resin base material 1 and the second resin base material 7. When the first resin base material 1 and the second resin base material 7 are exposed to the hologram agent, the first resin base material 1 and the second resin base material 7 are deteriorated, and a decrease in FOV (Field of View) and a decrease in clarity are likely to occur. However, in the configuration of this embodiment, the first barrier layer 3 and the second barrier layer 5 are provided between the first resin base material 1 and the hologram layer 4 and the second resin base material 7, respectively, thereby suppressing the penetration of the hologram agent into the first resin base material 1 and the second resin base material 7, thereby preventing deterioration of the first resin base material 1 and the second resin base material 7.

[0065] [Hard coat layer] The light guide plate for image display of this embodiment may have a hard coat layer on either or both of the surface of the first resin base material 1 and between the first resin base material 1 and the first barrier layer 3, for the purpose of increasing the pencil hardness of the surface of the first resin base material 1 or for the purpose of reducing the surface roughness Sa of the first barrier layer 3.

[0066] The hard coat layer is preferably formed from a curable resin composition. The curable resin composition is not particularly limited as long as it is cured by irradiation with energy rays such as electron beams, radiation, or ultraviolet rays, or by heating, but is preferably an ultraviolet-curable resin composition from the viewpoint of molding time and productivity.

[0067] Preferable examples of the curable resin constituting the curable resin composition include acrylate compounds, urethane acrylate compounds, epoxy acrylate compounds, carboxyl group-modified epoxy acrylate compounds, polyester acrylate compounds, copolymer acrylates, alicyclic epoxy resins, glycidyl ether epoxy resins, vinyl ether compounds, and oxetane compounds. These curable resins can be used alone or in combination of two or more. Among them, examples of curable resins that impart excellent surface hardness include radical polymerization type curable compounds such as polyfunctional acrylate compounds, polyfunctional urethane acrylate compounds, and polyfunctional epoxy acrylate compounds, and thermal polymerization type curable compounds such as alkoxysilanes and alkylalkoxysilanes.

[0068] The curable resin composition forming the hard coat layer may contain a leveling agent as a surface adjusting component. Examples of the leveling agent include a fluorine-based leveling agent, a silicone-based leveling agent, and an acrylic-based leveling agent. Among them, an acrylic-based leveling agent is preferred as the leveling agent because it can ensure excellent adhesion when the first barrier layer is laminated on the surface of the hard coat layer.

[0069] When the curable resin composition is cured by ultraviolet light, a photopolymerization initiator is used. Examples of the photopolymerization initiator include benzil, benzophenone and its derivatives, thioxanthones, benzil dimethyl ketals, α-hydroxyalkylphenones, hydroxyketones, aminoalkylphenones, and acylphosphine oxides. The amount of the photopolymerization initiator added is generally 0.1 to 8 parts by mass relative to 100 parts by mass of the curable resin composition.

[0070] The curable resin composition forming the hard coat layer may contain a refractive index adjusting component. Examples of the refractive index adjusting component include fine particles of a high refractive index metal compound such as zinc oxide, zirconium oxide, or titanium oxide, and fine particles of a low refractive index metal compound such as magnesium fluoride. Here, the size of the fine particles is preferably 5 to 50 nm, since it does not impair the transparency or total light transmittance of the hard coat layer. In addition, such fine particles of the refractive index adjusting component may be mixed with a curable resin composition in advance and then mixed into the curable resin composition forming the hard coat layer to be contained therein. In addition, the fine particles of the refractive index adjusting component may be mixed with a curable resin composition in advance and then directly used as the curable resin composition forming the hard coat layer. There are commercially available products that are a mixture of fine particles of the refractive index adjusting component with a curable resin composition in advance. Examples of such commercially available products include Lioduras TYZ, Lioduras TYT, and Lioduras TYM (all manufactured by Toyochem Co., Ltd.).

[0071] The curable resin composition forming the hard coat layer may contain additives such as lubricants such as silicon compounds, fluorine compounds or mixtures thereof, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants such as silicone compounds, fillers, glass fibers, silica, etc. These additives may be used alone or in combination of two or more.

[0072] The thickness of the hard coat layer is not particularly limited, but is preferably 1 to 20 μm. If the thickness of the hard coat layer is 1 μm or more, sufficient hardness can be imparted to the surface of the first resin base material 1. If the thickness of the hard coat layer is 20 μm or less, the first resin base material 1 can be ensured to have moldability and cuttability. Furthermore, it is also preferable in that the cure shrinkage of the hard coat layer is suppressed, and warping and undulation of the first resin base material 1 are not caused.

[0073] When the refractive index of the first resin base material 1 is na, the refractive index nb of the hard coat layer is preferably within the range of na±0.20, more preferably within the range of na±0.15, and even more preferably within the range of na±0.10. When the refractive index nb of the hard coat layer is within the range of na±0.20, the luminance value of the light guide plate for image display 8 is good and color unevenness can be prevented.

[0074] Methods for forming the hard coat layer include, for example, a method in which a coating of a curable resin composition is applied to the surface of the first resin substrate 1, and then a cured film is formed and laminated on the surface of the first resin substrate 1, but the method is not limited to this method. A known method is used as a lamination method with the first resin substrate 1. Known methods include, for example, a dip coating method, a natural coating method, a reverse coating method, a comma coater method, a roll coating method, a spin coating method, a wire bar method, an extrusion method, a curtain coating method, a spray coating method, and a gravure coating method. In addition, for example, a method of laminating a hard coat layer on the first resin substrate 1 using a transfer sheet having a hard coat layer formed on a release layer can be adopted. For the purpose of improving the adhesion between the hard coat layer and the first resin base material 1, a base film (primer layer) may be provided on the surface of the first resin base material 1 in advance.

[0075] <Method of manufacturing a light guide plate for image display> As an example of a method for manufacturing the light guide plate for image display of this embodiment, a method for manufacturing the light guide plate for image display 8 shown in FIG. 1 will be described. A first resin substrate 1 and a second resin substrate 7 are prepared ([Substrate preparation step]), and a first barrier layer 3 and a second barrier layer 5 are formed on the surfaces of the first resin substrate 1 and the second resin substrate 7, respectively, via a first anchor coat layer 2 and a second anchor coat layer 6, to obtain a first laminate 11 and a second laminate ([Barrier layer formation step]). As a method for forming the first barrier layer 3 and the second barrier layer 5, an appropriate manufacturing method is selected depending on the materials of the first barrier layer 3 and the second barrier layer 5. For example, a photosensitive material for forming a hologram is applied to the surface of the first barrier layer 3 in the first laminate 11. At this time, a transparent sealing layer having the same thickness as the hologram layer 4 may be provided on the outer periphery of the first barrier layer 3. The sealing layer seals the outer periphery of the hologram layer 4 after the hologram layer 4 is formed from the photosensitive material. The sealing layer is made of a transparent material, and for example, an epoxy resin, a silicone resin, an enethiol resin, or the like is used. Thereafter, the second laminate 12 is placed on the photosensitive material with the second barrier layer 5 facing the photosensitive material ([Light guide plate manufacturing process]). However, the above-mentioned manufacturing order is merely an example. For example, the second laminate 12 may be coated with a photosensitive material, and then the first laminate 11 may be placed on the hologram layer 4. Thereafter, the first resin substrate 1, the first anchor coat layer 2, the first barrier layer 3, the hologram layer 4, the second barrier layer 5, the second anchor coat layer 6 and the second resin substrate 7 are bonded together by a reduced pressure press to obtain a light guide plate 8 for image display. Thereafter, interference fringes corresponding to the diffraction pattern are formed on the photosensitive material, forming a diffraction grating in the photosensitive material. EXAMPLES

[0076] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the examples described below, and various modifications are possible without departing from the gist of the present invention.

[0077] Examples and Comparative Examples <Example 1> Polymethyl methacrylate (PMMA) ("Acrylite (registered trademark)" manufactured by Mitsubishi Chemical Corporation) is used as the material of the resin substrate. The resin substrate is a rectangular plate with a width of 200 mm, a length of 200 mm, and a thickness of 1 mm. The material of the hard coat layer is an acrylic UV-curable resin ("Shikoh UV1700B" manufactured by Mitsubishi Chemical Corporation). The material for the anchor coat layer is an acrylic resin ("Acrit 6BF-400" manufactured by Taisei Fine Chemical Co., Ltd.). The barrier layer is made of silicon oxynitride.

[0078] Using the above materials, a laminate is produced by carrying out a substrate preparation step and a barrier layer formation step described below.

[0079] [Base material preparation process] In the substrate preparation step, the resin substrate is washed and dried, and then a hard coat layer is formed on the resin substrate. The resin substrate is cut into a rectangular shape of 200 mm x 200 mm, and ultrasonically cleaned for 5 minutes while immersed in a 5% aqueous solution of a neutral detergent, Semiclean (registered trademark) M-LO (product name; manufactured by Yokohama Oil Industries Co., Ltd.). The resin substrate is then ultrasonically cleaned for 5 minutes while immersed in ultrapure water. The resin substrate is then rinsed with ultrapure water, air-dried, and then dried in a nitrogen atmosphere in an oven at 80°C. The air-dried evaluation sample is then UV-ozone cleaned for 1 minute in a UV-ozone cleaner. Next, an acrylic UV-curable resin, which is the material for the hard coat layer, is applied to both surfaces of the resin substrate using a bar coater, and after drying at 90°C for 1 minute, it is exposed to an integrated light dose of 500 mJ / cm 2 Both surfaces are exposed to light with a 5 μm thick hard coat layer.

[0080] [Barrier layer formation process] In the barrier layer forming step, a barrier layer is formed on the surface of the hard coat layer via an anchor coat layer. An acrylic resin, which is a material for the anchor coat layer, is applied to the surface of the hard coat layer with a bar coater and dried at 60° C. for 1 minute to provide an anchor coat layer with a thickness of 100 nm. A reactive sputtering method was used with silicon (manufactured by Kojundo Chemical Laboratory Co., Ltd.) as the target to obtain a 1.0×10 -1 A silicon nitride oxide film having a thickness of 100 nm is formed while supplying oxygen gas, nitrogen gas, and argon gas under a vacuum of 1 Pa. The total gas flow rate is set to 70 sccm. This completes the barrier layer forming process.

[0081] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0082] <Example 2> In Example 2, a laminate was produced in the same manner as in Example 1, except that the total gas flow rate during the formation of the barrier layer was set to 105 sccm.

[0083] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0084] <Example 3> In Example 3, a laminate was produced in the same manner as in Example 1, except that the material of the anchor coat layer was a urethane resin ("Vylon UR-1350" manufactured by Toyobo Co., Ltd.).

[0085] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0086] <Example 4> In Example 4, a laminate was produced in the same manner as in Example 3, except that the total gas flow rate during the formation of the barrier layer was set to 105 sccm.

[0087] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0088] <Example 5> In Example 5, a laminate is prepared in the same manner as in Example 3, except that the drying temperature of the anchor coat layer is 40°C. However, Example 5 is a reference example.

[0089] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0090] <Example 6> In Example 6, a laminate is produced in the same manner as in Example 1, except that the material of the anchor coat layer is a polyester resin ("Vylon 63SS" manufactured by Toyobo Co., Ltd.).

[0091] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0092] <Example 7> In Example 7, a laminate was produced in the same manner as in Example 6, except that the total gas flow rate during the formation of the barrier layer was set to 105 sccm.

[0093] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0094] <Example 8> In Example 8, a laminate is prepared in the same manner as in Example 6, except that the drying temperature of the anchor coat layer is 40°C. However, Example 8 is a reference example.

[0095] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0096] <Comparative Example 1> In Comparative Example 1, a laminate was prepared in the same manner as in Example 1, except that the drying temperature for the anchor coat layer was 40°C.

[0097] Table 1 shows the material and plate thickness of the resin substrate, the material of the hard coat layer, the material, film thickness and drying temperature of the anchor coat layer, and the material, film thickness, total gas flow rate and arrangement during film formation of the barrier layer.

[0098] <Measurement of surface roughness Sa> The laminate of each of the examples and comparative examples is used as a measurement sample, and the surface roughness Sa is measured by the Bert Scan method. Equipment: White light interferometer (VertScan, manufactured by Ryoka Systems Co., Ltd.) Observation conditions Objective lens: 5x Wavelength filter: 530white Measurement mode: wave Field of view size: 640 x 480 pixels Scan range: 7μm (start) -7μm (stop) Lamp aperture: 50% Contrast: 62% Brightness: 0% Analysis conditions Interpolation:Full Surface correction: quartic approximation

[0099] The "Surface roughness Sa" column in Table 1 shows the measurement results for Examples 1 to 8 and Comparative Example 1.

[0100] <Specular gloss measurement> The laminates of each Example and Comparative Example are used as measurement samples, and the specular gloss is measured using a gloss meter (manufactured by Suga Test Instruments Co., Ltd., product name: GS-4K) with the light source incident angle set to 60 degrees and the light receiver receiving angle set to 60 degrees. Prior to the measurement, the device is calibrated so that the specular gloss of the gloss standard plate, black flat optically polished glass No. 2012-015-B, is 92.2%.

[0101] The "Specular gloss" column in Table 1 shows the measurement results for Examples 1 to 8 and Comparative Example 1.

[0102] <Measurement of transmission b* value> The laminates of each of the examples and comparative examples are used as measurement samples, and the transmission b* value is measured using a spectrophotometer SD6000 manufactured by Nippon Denshoku Industries Co., Ltd., with a light source of C and a viewing angle of 2 degrees.

[0103] The measurement results for Examples 1 to 8 and Comparative Example 1 are shown in the "Transmission b* value" column of Table 1.

[0104] [Table 1]

[0105] <Explanation of Results> The laminates of Examples 1 to 8 had a specular gloss of 120% or more. These laminates had low transmission b*, and therefore were found to have low yellowness. On the other hand, the laminate of Comparative Example 1 had a specular gloss of 100% because an acrylic resin was used as the anchor coat layer and the drying temperature of the anchor coat layer was 40° C. It was found that the laminate of Comparative Example 1 had a high transmittance b* and a strong yellowish tinge. In Comparative Example 1, the acrylic resin used as the anchor coat layer did not harden sufficiently under drying conditions of 40°C for 1 minute, and the anchor coat layer hardened while being shaped during sputter deposition of the barrier layer, which is thought to have caused uneven deposition inside the film, resulting in a decrease in specular gloss.

[0106] <Production Examples and Comparative Production Examples> Next, a description will be given of an example of manufacturing a light guide plate for image display using the intermediates of the examples and comparative examples. The light guide plate for image display can be manufactured by carrying out the light guide plate manufacturing process described below.

[0107] <Production Example 1> In Production Example 1, the laminate of Example 1 is used to produce a light guide plate 8 for image display according to the embodiment. The photosensitive material for the hologram layer 4 is a mixture of 100 parts by weight of bisphenol epoxy resin jER (registered trademark) 1007 (degree of polymerization n=10.8, epoxy equivalent: 1750-2200, manufactured by Mitsubishi Chemical), 50 parts by weight of triethylene glycol diacrylate, 5 parts by weight of 4,4'-bis(tert-butylphenyl)iodonium hexafluorophosphate, and 0.5 parts by weight of 3,3'-carbonylbis(7-diethylamino)coumarin in 100 parts by weight of 2-butanone (hereinafter also referred to as "photosensitive material A").

[0108] [Light guide plate manufacturing process] In the light guide plate manufacturing process of Manufacturing Example 1, a light guide plate 8 for image display is manufactured using two sheets of the laminate of Example 1. A sealing layer having a width of 5 mm and a thickness of 5 μm is applied to the peripheral edge of the barrier layer of one of the laminates. The sealing layer is made of a transparent material and is not particularly limited as long as it is a material that can bond the barrier layers to each other. In Example 1, the optical adhesive Hardlock (registered trademark) OP-1045K (product name; manufactured by Denka Co., Ltd.) is used. This prepares an intermediate substrate with a seal layer step, the opening of which is surrounded by the seal layer and has dimensions of 50 mm x 50 mm. Thereafter, the above-mentioned photosensitive material A is applied as a photopolymer material for a hologram onto the intermediate substrate by spin coating. The photosensitive material is applied so that the thickness after drying is 5 μm. Thereafter, the other intermediate substrate is laminated on the seal layer and the photosensitive material so that the barrier layer faces the barrier layer of the intermediate substrate with the seal layer, and the two are press-laminated under reduced pressure under the conditions of absolute pressure of 5 kPa, temperature of 70° C., and press pressure of 0.04 MPa. After this, a diffraction grating is recorded on the press-laminated hologram layer. In this process, the temperature of the laminate including the hologram layer is kept at 20°C. The diffraction grating is made by irradiating the laminate with two laser beams and adjusting the irradiation angle and intensity of each to form interference fringes so that the required diffraction pattern is formed. This records the diffraction grating in the hologram layer. A specific diffraction grating is a color display diffraction grating that diffracts light in the red, green, and blue wavelength regions incident as image light into the incident portion, and outputs the light from the display portion at positions corresponding to the pixels of the image light. Thereafter, while the laminate including the hologram layer was kept at 20°C, it was irradiated with ultraviolet light (wavelength 365 nm, irradiance 80 W / cm 2 ) is irradiated onto the entire surface of the laminate from one side for 30 seconds. A high-pressure mercury lamp is used as the source of ultraviolet light. As a result, the sealing layer is cured, and the light guide plate 8 for image display of Production Example 1 is produced.

[0109] [Manufacturing Examples 2 to 8] In Production Examples 2 to 8, the light guide plates 8 for image display of Production Examples 2 to 8 are produced in the same manner as Production Example 1, except that two sheets of the laminates of Examples 2 to 8 are used, respectively.

[0110] [Comparative Manufacturing Example 1] In Comparative Production Example 1, the light guide plate for image display of Comparative Production Example 1 is produced in the same manner as in Production Example 1, except that two sheets of the laminate of Comparative Example 1 are used.

[0111] <Evaluation of clarity of displayed image> Next, a method for evaluating the clarity of the displayed image of each production example will be described. The light guide plates for image display of Production Examples 1 to 8 and Comparative Production Example 1 are attached to an image display device. The image display device is provided with an optical system that inputs image light to be displayed into the input portion of the light guide plate for image display 8, a driving power source, and a circuit system that supplies image information and the like to obtain the image light. As input images used for the evaluation, a white image and an image displaying characters are used. The evaluation was performed by visually judging the visibility of a white image and a character display image. The character image displayed was "ABCDE" within the size of 10mm x 100mm. If no rainbow color is visible in the white image and the characters are clearly visible in the character display image, the image is judged as good (shown as "A" in Table 2). If a slight rainbow color is visible in the white image, but the characters are clearly visible in the character display image, it is judged as fair (shown as "B" in Table 2). If rainbow colors are visible in at least a part of the white image and the outlines of the characters in the character display image are blurred, the image is judged as no good (marked as "C" in Table 2).

[0112] The "Clarity" column in Table 2 shows the results of the clarity evaluation for Production Examples 1 to 8 and the Comparative Production Example.

[0113] [Table 2]

[0114] <Explanation of results> As shown in Table 2, in the light guide plates for image display of Production Examples 1 to 8, the specular gloss of the laminate was 120% or more, so that the clarity could be judged as "good" or "fair." On the other hand, in the light guide plate for image display of Comparative Production Example 1, the specular gloss of the laminate is low at 100%, and therefore the clarity can be judged as "unacceptable." [Industrial Applicability]

[0115] The light guide plate for image display of the present invention has good clarity and is useful for display device applications such as VR and AR applications. For example, the light guide plate for image display of the present invention is useful for display device applications such as head-up displays, wearable displays, and head-mounted displays. [Explanation of symbols]

[0116] 1 First resin base material 2 First anchor coat layer 3 First Barrier Layer 4 Holographic Layer 5 Second Barrier Layer 6 Second anchor coat layer 7 Second resin base material 8 Light guide plate for image display 11 First laminate 12 Second laminate

Claims

1. A method for manufacturing a light guide plate for image display, comprising the steps of: a substrate preparation step in which a first resin substrate and a second resin substrate are prepared; a barrier layer forming step in which a first barrier layer is formed on a surface of the first resin substrate via a first anchor coat layer to obtain a first laminate, and a second barrier layer is formed on a surface of the second resin substrate via a second anchor coat layer to obtain a second laminate; a light guide plate fabrication step in which a hologram layer is formed on a surface of the first barrier layer in the first laminate, and the second laminate is placed on the hologram layer with the second barrier layer facing the hologram layer, The material of the first anchor coat layer and the second anchor coat layer is an acrylic resin, a urethane resin, or a polyester resin, In the barrier layer forming step, the drying temperature of the first anchor coat layer and the second anchor coat layer is 60 to 120° C., The method for producing a light guide plate for image display, wherein the specular gloss at an incident angle of 60 degrees on the side of the first laminate in contact with the hologram layer is 120% or more.

2. 2. The method for producing a light guide plate for image display according to claim 1, wherein the first resin base material and the second resin base material contain at least one resin selected from the group consisting of poly(meth)acrylic resins, epoxy resins, cyclic polyolefin resins, and polycarbonate resins.

3. The method for producing a light guide plate for image display according to claim 1 , wherein the first barrier layer and the second barrier layer contain an inorganic material.

4. 4. The method for producing a light guide plate for image display according to claim 3, wherein the inorganic material is at least one selected from the group consisting of silicon oxide, silicon nitroxide, diamond-like carbon, aluminum oxide and glass.

5. The method for manufacturing a light guide plate for image display according to any one of claims 1 to 4, wherein the first anchor coat layer and the second anchor coat layer contain at least one selected from the group consisting of an acrylic resin, a urethane resin, and a polyester resin.

6. The method for producing a light guide plate for image display according to claim 5 , wherein the first anchor coat layer and the second anchor coat layer contain an acrylic resin or a urethane resin.

7. The method for producing a light guide plate for image display according to claim 6 , wherein the first anchor coat layer and the second anchor coat layer contain an acrylic resin.

8. The method for producing a light guide plate for image display according to any one of claims 1 to 7, wherein in the substrate preparation step, a hard coat layer is formed on the first resin substrate and the second resin substrate.

Images