JP2022129942A - Light guide plate for image display - Google Patents

Abstract

To provide a light guide plate for image display that can suppress degradation of a hologram layer and has an excellent resistance to a solvent.SOLUTION: A light guide plate 8 for image display includes: a first resin base material 1; a first laminate body in which a first anchor coat layer 2 and a first barrier layer 3 are deposited in that order; and a hologram layer 4. The first anchor coat layer 2 is made of a resin composition including a binder resin with a hydroxyl group and a hardening agent with an isocyanate group. The mole ratio NCO/OH of the isocyanate group (NCO) of the hardening agent to the hydroxyl group (OH) of the binder resin is at least 0.8.SELECTED DRAWING: Figure 1

Description

The present invention relates to a light guide plate for image display.

2. Description of the Related Art An image display light guide plate may be used in a display device. For example, in a display device using VR (Virtual Reality) technology or AR (Augmented Reality) technology, an image display light guide plate in which a hologram layer is supported by a transparent substrate is used. The hologram layer is formed with holograms having various optical functions such as waveguiding, reflection and diffraction.
Materials used as hologram materials for forming hologram layers are often photosensitive compositions containing bases such as radically polymerizable monomers, polyacids or amines, which may deteriorate the resin substrate. Holographic materials are also known to deteriorate due to moisture absorption. Therefore, a display device in which a hologram layer is supported by a resin base material is likely to deteriorate in a hot and humid environment.

Patent Document 1 describes forming a photosensitive material layer for forming a hologram on an optically transparent resin substrate, and coating the photosensitive material layer with an aqueous polymer protective barrier. US Pat. No. 5,300,000 suggests that the water-based polymeric protective barrier is provided for the purpose of resisting attack by moisture.

JP-A-5-181400

However, the technique described in Patent Document 1 has the following problems.
In the technique described in Patent Document 1, a resin substrate is in close contact with the surface of the photosensitive material layer opposite to the water-based polymer protective barrier.
Therefore, the photosensitive material may corrode the resin substrate in a high-temperature environment.
Furthermore, since the resin substrate contains moisture, the moisture diffuses into the photosensitive material layer through the contact surface with the photosensitive material layer. In addition, since the substrate is exposed to the outside, moisture continues to permeate the substrate from the outside. As a result, since moisture permeates into the photosensitive material layer through the resin substrate, even if moisture is blocked by the water-based polymer protective barrier, the photosensitive material layer deteriorates over time due to moisture from the substrate side. I can't control it.

In addition, the image display light guide plate is required to have good solvent resistance because it may be subjected to solvent washing (cleaning) or come into contact with the hologram material when it is incorporated into a module.

An object of the present invention is to provide a light guide plate for image display that can suppress deterioration of the hologram layer and has good solvent resistance.

The present inventors have found that by providing an anchor coat layer made of a specific material and a barrier layer between the resin base material and the hologram layer, the deterioration of the hologram layer can be suppressed in the light guide plate for image display, and The inventors have found that good solvent resistance can be obtained, and completed the present invention.
That is, the present invention has the following aspects.

[1] A first laminate comprising a first resin substrate, a first anchor coat layer and a first barrier layer in this order, and a hologram layer, wherein the first anchor coat layer is a binder resin having a hydroxyl group. and an isocyanate compound, wherein the molar ratio NCO/OH of the isocyanate groups (NCO) of the isocyanate compound to the hydroxyl groups (OH) of the binder resin is 0.8 or more. light plate.
[2] The set forth in [1], wherein the first resin base material contains at least one resin selected from the group consisting of poly(meth)acrylic resins, epoxy resins, cyclic polyolefin resins and polycarbonate resins. Light guide plate for image display.
[3] According to [1] or [2], wherein the first anchor coat layer contains, as the binder resin, at least one resin selected from the group consisting of acrylic resins, urethane resins and polyester resins. Light guide plate for image display.
[4] The light guide plate for image display according to any one of [1] to [3], wherein the first barrier layer contains an inorganic material.
[5] Any one of [1] to [4], wherein the first barrier layer contains at least one inorganic material selected from the group consisting of silicon oxide, silicon oxynitride, diamond-like carbon and aluminum oxide. The light guide plate for image display according to (1).
[6] The first barrier layer contains silicon oxynitride as a main component, and the nitrogen elemental composition in the first barrier layer determined by X-ray photoelectric molecular spectroscopy (XPS) is 7 atm % or more. ] to the light guide plate for image display according to any one of [5].
[7] The light guide plate for image display according to any one of [1] to [6], wherein the first laminate has first hard coat layers on both surfaces of the first resin base material.
[8] The light guide plate for image display according to any one of [1] to [7], wherein the first laminate has a water vapor transmission rate of less than 0.01 g/m ² /day.

ADVANTAGE OF THE INVENTION According to this invention, the deterioration of a hologram layer can be suppressed and the light-guide plate for image displays which has favorable solvent resistance can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of the light guide plate for image display of the present invention.

An embodiment of the present invention will be described below. However, the present invention is not limited to the embodiments described later, and various modifications are possible without departing from the gist of the present invention.
When "to" is used to indicate a numerical range, the numbers on both sides of "to" are included in the numerical range.
In the present invention, "(meth)acryl" includes "acryl" and "methacryl". For example, "poly(meth)acrylic resin" includes "polyacrylic resin" and "polymethacrylic resin". Similarly, "(meth)acrylate" includes "acrylate" and "methacrylate", "(meth)acryloyl" includes "acryloyl" and "methacryloyl", and "(meth)acryloyloxy" includes " acryloyloxy” and “methacryloyloxy”.

[Light guide plate for image display]
An image display light guide plate according to an embodiment of the present invention will be described.
The light guide plate for image display of this embodiment has a first laminate including a first resin base material, a first anchor coat layer and a first barrier layer, and a hologram layer. The first resin substrate, the first anchor coat layer, the first barrier layer and the hologram layer are arranged in this order in the thickness direction. The first laminate 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 laminate is arranged on both surfaces of the hologram layer, the first laminate arranged on one surface of the hologram layer is simply referred to as the first laminate, and the first laminate is arranged on the other surface of the hologram layer. The above-described first laminate is referred to as a second laminate. In the thickness direction of the second laminate, a second barrier layer, a second anchor coat layer, and a second resin base material are arranged in this order from the hologram layer side. In this case, the hologram layer is sandwiched between the first barrier layer of the first laminate and the second barrier layer of the second laminate, and is provided on the other surface of the first barrier layer. is laminated with the first anchor coat layer and the first resin base material, and the second anchor coat layer and the second resin base material are laminated on the other surface of the second barrier layer. In the present embodiment, the first laminate and the second laminate may be collectively referred to as "laminate" hereinafter. Hereinafter, the first resin base material and the second resin base material may be collectively referred to simply as "resin base material". Further, the first anchor coat layer and the second anchor coat layer may be collectively referred to as "anchor coat layer" hereinafter. Further, the first barrier layer and the second barrier layer may be collectively referred to as simply "barrier layer" hereinafter.

Between the first resin base material and the first anchor coat layer, between the first anchor coat layer and the first barrier layer, and between the first barrier layer and the hologram layer, one More than one transparent layer may be arranged. Examples of the transparent layer include a hard coat layer.

The image display light guide plate has an incident portion for receiving image light and a display portion for displaying an image by the image light.
The hologram layer is arranged between the entrance section and the display section. A diffraction grating pattern is formed on the hologram layer for guiding at least the image light incident from the incident portion to the display portion and for emitting the image light from the display portion.
The diffraction grating pattern in the display section transmits at least part of external light entering from the outside of the image display light guide plate. In addition, external light enters from the surface opposite to the display section.

The image light incident on the incident portion is guided in the hologram layer and emitted from the display portion to the outside. On the other hand, external light also passes through the resin base material and the display section, so that an observer of the display section can observe both the image light and the external light within the field of view.
The image display light guide plate of the present embodiment can be used in a display device or the like using VR (virtual reality) technology or AR (augmented reality) technology. be able to.
In addition to display applications, the image display light guide plate of the present embodiment is typified by a combiner for a head-up display (HUD, Head-Up Display) mounted on a vehicle or a reflector for a reflective liquid crystal display device. It can be used in devices such as a hologram optical element (HOE, Holographic Optical Element).

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

In the image display light guide plate 8 shown in FIG. 1, the first resin base material 1, the first anchor coat layer 2, the first barrier layer 3, the hologram layer 4, the second barrier layer 5, and the second anchor coat are arranged in the thickness direction. The layer 6 and the second resin base material 7 are arranged in this order.
The plan view shape of the image display light guide plate 8 is not particularly limited. For example, the image display light guide plate 8 may be shaped into a shape that can be attached to the display device used.
For example, the image display light guide plate 8 may be a rectangular plate larger than the shape to be attached to the display device. In this case, the image display light guide plate 8 is molded by being cut 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 have a flat plate shape, or may have a curved plate shape as necessary.
In the following, an example in which the image display light guide plate 8 is a flat plate having a rectangular shape in plan view will be described.

<First laminate>
The first laminate comprises a first resin base material 1, a first anchor coat layer 2 and a first barrier layer 3 in this order. By arranging the first laminate on the surface of the hologram layer 4, the image display light guide plate 8 can suppress deterioration of the hologram layer and obtain good solvent resistance.
In addition, the “solvent resistance” in the present invention means that when a solvent such as isopropyl alcohol is dropped on the surface of the first barrier layer 3 side and wiped off with a wipe, the first barrier layer 3 becomes the same as the first resin base material 1 . It means not to peel from. More specifically, it is evaluated by the method described in Examples.

(optical properties)
Although the total light transmittance of the first laminate is not particularly limited, it is preferably 90% or more, more preferably 91% or more, and even more preferably 92% or more. When the total light transmittance of the first laminate is 90% or more, the luminance value of the image display light guide plate 8 becomes more favorable.

(barrier property)
The water vapor transmission rate of the first laminate is preferably less than 0.01 g/m ² /day, more preferably less than 0.008 g/m ² /day, still more preferably less than 0.006 g/m ² /day, and 0.01 g/m 2 /day. Even more preferably less than 0.004 g/m ² /day. When the water vapor transmission rate of the first laminate is less than 0.01 g/m ² /day, deterioration of the hologram layer 4 can be further suppressed.

<<First resin substrate 1>>
The first resin base material 1 is arranged at the outermost part in the thickness direction of the light guide plate 8 for image display. The first resin base material 1 is arranged on the surface of the image display light guide plate 8 on the display image exit side.
The first resin base material 1 has a shape similar to the outer shape of the light guide plate 8 for image display.
The first resin substrate 1 transmits image light emitted from the hologram layer 4 and external light transmitted through the second resin substrate 7 and the hologram layer 4, which will be described later.

Although the thickness of the first resin base material 1 is not particularly limited, it is preferably 0.05 to 10 mm.
Although the lower limit of the thickness of the first resin base material 1 is not particularly limited, it is preferably 0.1 mm or more, more preferably 0.2 mm or more, from the viewpoint of improving scratch resistance.
Although the upper limit of the thickness of the first resin base material 1 is not particularly limited, it is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 2 mm or less from the viewpoint of improving moldability and total light transmittance.
In this specification, the thickness of the first resin base material 1 can be measured by a dial gauge method using a stylus, a micrometer, or the like.

Although the total light transmittance of the first resin substrate 1 is not particularly limited, it is preferably 80% or more, more preferably 90% or more. When the total light transmittance of the first resin base material 1 is 80% or more, the luminance value of the light guide plate 8 for image display becomes better.

The first resin substrate 1 preferably contains a thermoplastic resin from the viewpoint of improving optical properties, impact resistance, scratch resistance, and moldability.
Examples of the thermoplastic resin include polyolefin resins such as homopolymers or copolymers of alkenes such as ethylene, propylene and butene, amorphous polyolefin resins such as cyclic polyolefin resins, polyethylene terephthalate (PET) and polyester resins such as polyethylene naphthalate (PEN); cellulose resins such as triacetyl cellulose, diacetyl cellulose and cellophane; polyamide resins such as nylon 6, nylon 66, nylon 12 and copolymer nylon; Combined partial hydrolyzate (EVOH), polyimide-based resin, polyetherimide-based resin, polysulfone-based resin, polyethersulfone-based resin, polyetheretherketone-based resin, polycarbonate-based resin, polyvinyl butyral-based resin, polyarylate-based resin , fluorine resin, 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, phenolic resin , epoxy resins, polynorbornene, styrene-isobutylene-styrene block copolymers (SIBS), allyl diglycol carbonate, and biodegradable resins. These thermoplastic resins can be used singly or in combination of two or more. Further, the first resin base material 1 may have a structure in which layers made of two or more materials selected from the group consisting of the thermoplastic resins are laminated.
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.
Among these, poly(meth)acrylic resins are preferable because they are excellent in scratch resistance and moldability.

(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, and i-butyl (meth)acrylate. , t-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, norbornyl (meth)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, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylates and diethylaminoethyl (meth)acrylates. These monomers may be used by polymerizing alone, or two or more of them may be polymerized and used.

Further, other monomers copolymerizable with the monomers constituting the poly(meth)acrylic resin may be added. The above other monomers may be monofunctional monomers, i.e., compounds having one polymerizable carbon-carbon double bond in the molecule, or polyfunctional monomers, i.e., intramolecularly polymerized It may also be a compound having at least two carbon-carbon double bonds of the same type.
Examples of the monofunctional monomer 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 the polyfunctional monomer include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate and trimethylolpropane triacrylate, allyl acrylate, allyl methacrylate and silica. Alkenyl esters of unsaturated carboxylic acids such as allyl micate, polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate, triallyl cyanurate and triallyl isocyanurate, and aromatic polyalkenyl compounds such as divinylbenzene is mentioned.
The monofunctional monomer and the polyfunctional monomer may be used singly or in combination of two or more.

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

<<First anchor coat layer 2>>
The first anchor coat layer 2 is arranged between the first resin base material 1 and the first barrier layer 3 .
By providing the first anchor coat layer 2, the adhesion between the first resin base material 1 and the first barrier layer 3 is improved, and barrier properties and solvent resistance are improved.

The first anchor coat layer 2 alleviates the residual stress of the first barrier layer 3 to prevent cracks from occurring in the first barrier layer 3 when the first barrier layer 3 is formed by dry film formation. It also functions as a preventive measure.
From the viewpoint of sufficiently relaxing the residual stress of the first barrier layer 3, the thickness of the first anchor coat layer 2 is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more.
On the other hand, from the viewpoint of preventing excessive deformation of the first barrier layer 3 due to residual stress, the thickness of the first anchor coat layer 2 is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less.

Although the total light transmittance of the first anchor coat layer 2 is not particularly limited, it is preferably 80% or more, more preferably 90% or more. When the total light transmittance of the first anchor coat layer 2 is 80% or more, the luminance value of the light guide plate 8 for image display becomes favorable.

Further, when n1 is the average refractive index of the first resin substrate 1 and the first barrier layer 3, the refractive index n2 of the first anchor coat layer 2 is preferably within the range of n1±0.20. It is more preferably in the range of 0.15 and even more preferably in the range of n1±0.10. When the refractive index n2 of the first anchor coat layer 2 is within the range of n1±0.20, the luminance value of the image display light guide plate 8 can be improved and color unevenness can be prevented.
The refractive index is measured with an Abbe refractometer (NAR-4T, manufactured by Atago).

The first anchor coat layer 2 is made of a resin composition containing a binder resin having a hydroxyl group and an isocyanate compound. Solvent resistance becomes favorable because the binder resin is crosslinked by the isocyanate compound.

The binder resin having a hydroxyl group is not particularly limited, but includes acrylic resins, urethane resins, polycarbonate resins, polyether resins and polyester resins, and includes acrylic resins, urethane resins and polyester resins. At least one selected from the group is preferred. The binder resin is preferably a polyol having two or more hydroxyl groups in one molecule.

The hydroxyl value of the binder resin is preferably 0.1 to 300 mgKOH/g, more preferably 1 to 200 mgKOH/g, even more preferably 5 to 150 mgKOH/g, from the viewpoint of increasing the crosslink density.

The isocyanate compound is preferably an aromatic or aliphatic diisocyanate or a trivalent or higher polyisocyanate. Examples of isocyanate compounds include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, dicyclohexyl diisocyanate, or trimers thereof. body.

The molar ratio NCO/OH of the isocyanate groups (NCO) of the isocyanate compound to the hydroxyl groups (OH) of the binder resin is 0.8 or more, preferably 0.9 or more, more preferably 1 or more. Although the upper limit is not particularly limited, 10 or less is preferable.
When the isocyanate group of the isocyanate compound contains more isocyanate groups than the hydroxyl groups of the binder resin, part of the isocyanate compound also reacts with the functional groups on the surface of the first resin base material 1 to form bonds. 1 The adhesion with the anchor coat layer 2 is improved.

The resin composition constituting the first anchor coat layer 2 includes a resin other than the binder resin having a hydroxyl group, a silane coupling agent, a sensitizer, a cross-linking agent other than an isocyanate compound, an ultraviolet absorber, a polymerization inhibitor, an interface Activators, fillers, release agents and other thermoplastic resins may be added. These additives can be used singly or in combination of two or more.
Examples of resins other than the binder resin having a hydroxyl group include fluorine-based resins, polyethersulfone-based resins, silicone-based resins, cycloolefin-based resins, thermoplastic polyimide-based resins, polyamide-based resins, polyamideimide-based resins, poly Examples include arylate-based resins, polysulfone-based resins, polyetherimide-based resins, polyetheretherketone-based resins, polyether silicon-based resins, and polyphenylene sulfide-based resins.
Examples of cross-linking agents other than the above isocyanate compounds include peroxide-based cross-linking agents, epoxy-based cross-linking agents and imine-based cross-linking agents.

As a method for forming the first anchor coat layer 2, for example, a resin composition for forming the first anchor coat layer 2 is applied to the first resin substrate 1, and the first barrier layer 3 is further laminated thereon. The laminate can be processed and formed by methods such as pressing, nip rolls, heat lamination, and the like. 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.

<<First barrier layer 3>>
The first barrier layer 3 is arranged between the first anchor coat layer 2 and the hologram layer 4 described later.
The first barrier layer 3 prevents gases such as water vapor and oxygen permeating from the outside of the image display light guide plate 8 and the first resin base material 1 from permeating the hologram layer 4 and deteriorating it.
Therefore, the smaller the oxygen permeability and water vapor permeability of the first barrier layer 3, the better.
The oxygen permeability of the first barrier layer 3 is preferably 1 cm ³ /m ² /day/atm or less.
The water vapor transmission rate of the first barrier layer 3 is preferably 1 g/m ² /day or less, more preferably 0.5 g/m ² /day or less, and even more preferably 0.1 g/m ² /day or less.
Here, the oxygen permeability is the oxygen permeability measured 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).

When the first barrier layer 3 is formed by dry film formation, residual stress may be generated such that the first barrier layer 3 curls outward. From the viewpoint of preventing the residual stress from becoming too large, the thickness of the first barrier layer 3 is preferably 150 nm or less, more preferably 130 nm or less.
On the other hand, from the viewpoint of improving barrier properties, the thickness of the first barrier layer 3 is preferably 5 nm or more, more preferably 10 nm or more.

The first barrier layer 3 preferably has a higher refractive index than the first resin substrate 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 or more and 3.0 or less. If the first barrier layer 3 has a higher refractive index than the first resin base material 1, light passing through the first resin base material 1 via the first barrier layer 3 is optically dense. The light is incident on the optically coarse first resin base material 1 from the first barrier layer 3 , and the output angle of the light from the first barrier layer 3 toward the first resin base material 1 is the same as that of the first barrier layer 3 . It increases according to the refractive index difference with the first resin base material 1 . Thereby, the FOV (Field of View) in the light guide plate for image display can be widened.

The first barrier layer 3 preferably contains an inorganic material. Among them, it is more preferable to contain at least one selected from the group consisting of silicon oxide, silicon oxynitride, diamond-like carbon (DLC) and aluminum oxide. Furthermore, from the viewpoint of improving the total light transmittance and barrier properties, the first barrier layer 3 further preferably contains silicon oxide or silicon oxynitride, and from the viewpoint of barrier properties and solvent resistance, silicon oxide It is even more preferable to contain nitride as a main component. Here, “the main component of the first barrier layer 3” refers to a component that accounts for 50% by mass or more of all the components that constitute the first barrier layer 3. As shown in FIG. The ratio of silicon oxynitride in the first barrier layer 3 is not particularly limited as long as it is 50% by mass or more with respect to the total mass of the first barrier layer 3, but is preferably 60% by mass or more, and 70% by mass or more. More preferably, 80% by mass or more is even more preferable.

When the first barrier layer 3 contains silicon oxynitride, the nitrogen element composition in the first barrier layer 3 determined by X-ray photoelectron spectroscopy (XPS) is preferably 7 atm% or more, 8 atm % or more is more preferable, 9 atm % or more is still more preferable, and 10 atm % or more is even more preferable. When the nitrogen elemental composition is 7 atm % or more, the first barrier layer 3 has good solvent resistance.
From the viewpoint of optical properties, the nitrogen elemental composition in the first barrier layer 3 is preferably 40 atm % or less, more preferably 30 atm % or less, and even more preferably 25 atm % or less.

When the first barrier layer 3 is made of silicon oxide or silicon oxynitride, the first barrier layer 3 may be formed by a conventionally known method such as vacuum deposition, sputtering, ion plating or plasma CVD. It can be formed by a membrane method. Among them, the sputtering method is preferable as the film forming method from the viewpoint of obtaining a good barrier property and improving the clarity of the light guide plate 8 for image display.
In order to improve the adhesion between the first anchor coat layer 2 and the first barrier layer 3, the surface of the first anchor coat layer 2 is subjected to corona discharge treatment or low-temperature plasma treatment, or coated with a silane coupling agent. Alternatively, a surface treatment such as applying a mixture of saturated polyester and isocyanate may be applied.
When the first barrier layer ³ is formed by, for example, a vacuum deposition method, silicon, silicon monoxide, silicon dioxide, silicon nitrogen oxide, or a mixture thereof is used as the evaporation material, and the Under a vacuum of 2.0×10 ⁻¹ Pa, it is heated and evaporated by an electron beam, resistance heating, or high-frequency heating method.
Also, as a film formation method, for example, a reactive vapor deposition method performed while supplying oxygen gas or nitrogen gas can be employed.
Further, when the film is formed by the ^sputtering method, for example, silicon, silicon monoxide, silicon dioxide, silicon oxynitride, or a mixture thereof is used as a target, ^and the A film can be formed under a vacuum of ¹ Pa.
As the sputtering method, for example, a reactive sputtering method performed while supplying oxygen gas, nitrogen gas, or argon gas can also be adopted.

The nitrogen elemental composition in the first barrier layer 3 can be adjusted by the nitrogen flow rate, power and film formation pressure during film formation.
In particular, in order to make the nitrogen elemental composition 7 atm % or more, the ratio O ₂ /N ₂ between the oxygen flow rate O ₂ [sccm] and the nitrogen flow rate N ₂ [sccm] is preferably 0.10 to 1.5, more preferably 0.12 to 0.12. 1.0 is more preferable, and 0.15 to 1.0 or more is even more preferable.
Also, the power is preferably 1000 to 2000W. Since O ₂ /N ₂ and power affect each other, when O ₂ /N ₂ is 0.10 or more and less than 0.15, the power is preferably 1000 W or more and less than 1500 W, and O ₂ /N ₂ is When it is 0.15 or more and 1.5 or less, it is preferable to set the power to 1500 W or more and 2000 W or less.
The film forming pressure is preferably 1.0×10 ⁻² to 2.0×10 ⁻¹ Pa, more preferably 5.0×10 ⁻² to 1.5×10 ⁻¹ Pa.

The silicon oxide or silicon oxynitride forming the first barrier layer 3 may contain calcium, magnesium, or their oxides in an amount of 10% by mass or less as impurities.

When the first barrier layer 3 is formed by DLC, a suitable well-known coating method such as plasma CVD, ion plating, or physical vapor deposition such as ion beam sputtering can be used.

When the first barrier layer 3 is made of aluminum oxide, the first barrier layer 3 may for example be made only of Al ₂ O ₃ or selected from the group consisting of Al, AlO and Al ₂ O ₃ . It may be formed by mixing two or more kinds. The atomic ratio of Al:O in the aluminum oxide layer varies depending on the conditions for producing the aluminum oxide layer. The aluminum oxide layer that can be used as the first barrier layer 3 may contain other components in trace amounts (up to 3% with respect to the total components) as long as the barrier performance is not impaired.

The method of forming the first barrier layer 3 with aluminum oxide is not particularly limited. For example, as a method of forming the first barrier layer 3, 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) may be used.
For example, in the vacuum deposition method, Al, Al ₂ O ₃ or the like may be used as the deposition source material, and resistance heating, high-frequency induction heating, electron beam heating, or the like may be used as the heating method for the deposition source. . In the vacuum deposition method, oxygen, nitrogen, water vapor, or the like may be introduced as a reactive gas, or reactive deposition using means such as addition of ozone or ion assist may be used. Furthermore, a bias may be applied to the film formation surface, or the temperature of the film formation surface may be raised or cooled. The same applies to other film forming methods such as the PVD method and the CVD method other than the sputtering method and other vacuum vapor deposition methods.

<Hologram layer 4>
The hologram layer 4 is disposed on the surface of the first barrier layer 3 opposite to the surface to which the first anchor coat layer 2 adheres. The hologram layer 4 is appropriately formed with a diffraction grating corresponding to the function that the light guide plate 8 for image display should have.

The material of the hologram layer 4 is not particularly limited, and a known hologram-forming resin material can be used.
As a material for the hologram layer 4, for example, a hologram recording material containing a thermosetting resin having at least one solvent-soluble and cationically polymerizable ethylene oxide ring in a structural unit and a radically polymerizable ethylenic monomer (Japanese Unexamined Patent Publication (Kokai) No. 9-1999). -62169, JP-A-11-161141 and JP-A-2002-310932).
Specifically, the hologram layer 4 is composed of epoxy resin such as bisphenol epoxy resin, (meth)acrylate such as triethylene glycol diacrylate, and 4,4′-bis(tert-butylphenyl)iodonium hexafluorophosphate. It is preferably formed from a photosensitive material containing a photopolymerization initiator such as 3,3′-carbonylbis(7-diethylamino)coumarin, a wavelength sensitizer such as 3,3′-carbonylbis(7-diethylamino)coumarin, and an organic solvent such as 2-butanone.

<Second laminate>
The second laminate comprises a second barrier layer 5, a second anchor coat layer 6 and a second resin base material 7 in this order. Various physical properties of the second laminate may be different from those of the first laminate.

<<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. As the second barrier layer 5, the same configuration as that exemplified in the description of the first barrier layer 3 is used. However, the thickness, material, etc. of the second barrier layer 5 may be different from those of the first barrier layer 3 .

<<Second anchor coat layer 6>>
The second anchor coat layer 6 is arranged between the second barrier layer 5 and the second resin base material 7 . As the second anchor coat layer 6, the same configuration as 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 .

<<Second resin base material 7>>
The second resin base material 7 is laminated on the surface of the second barrier layer 5 . As the second resin base material 7, the same configuration as that exemplified in the description of the first resin base material 1 is used. 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, the second resin base material 7 is disposed on the surface of the light guide plate 8 for image display on the side of the external light incident side opposite to the display image output side, so that the surface hardness is higher than that of the first resin base material 1 . Expensive materials may be used.

<Light guide plate for image display 8>
In the image display light guide plate 8, the first anchor coat layer 2 and the first barrier layer 3 are provided 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. , a second barrier layer 5 and a second anchor coat layer 6 are disposed.
A certain amount of gas outside the image display light guide plate 8 passes through the first resin base material 1 and the second resin base material 7 or accumulates therein. At this time, moisture is particularly likely to accumulate in the first resin base material 1 and the second resin base material 7 .
However, according to the configuration of the present embodiment, the first barrier layer 3 and the second barrier layer 5 can shield the moisture that permeates the first resin base material 1 and the second resin base material 7 from the outside. The permeation of water vapor to the hologram layer 4 is suppressed, and deterioration of the hologram layer 4 can be prevented.

Also, the chemical resistance of the first resin base material 1 and the second resin base material 7 is significantly lower than that of glass, although the degree of chemical resistance varies depending on the type of resin material. Therefore, the first resin substrate 1 and the second resin substrate 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 transmitted through the first resin base material 1 and the second resin base material 7. Also, the hologram agent tends 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 the FOV (Field of View) is lowered and the definition is lowered. is more likely to decline.
However, according to the configuration of this embodiment, by providing the first barrier layer 3 and the second barrier layer 5 between the first resin base material 1 and the second resin base material 7 and the hologram layer 4, respectively, By suppressing penetration of the hologram agent into the first resin base material 1 and the second resin base material 7, deterioration of the first resin base material 1 can also be prevented.

<Hard coat layer>
In the image display light guide plate of the present embodiment, for the purpose of increasing the pencil hardness of the surface of the first resin base material, or for the purpose of reducing the surface roughness Sa of the first barrier layer, the first resin base material One surface or both surfaces may have a hard coat layer.

The hard coat layer is preferably formed from a curable resin composition. The curable resin composition is not particularly limited, but is preferably cured by irradiation with energy rays such as electron beams, radiation or ultraviolet rays, or cured by heating. From the viewpoint of molding time and productivity, ultraviolet rays A curable resin composition is more preferred.

Examples of curable resins 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 Examples include ether epoxy resins, vinyl ether compounds and oxetane compounds. The curable resins may be used singly or in combination of two or more.
Among these curable resins, radically polymerizable curable compounds such as polyfunctional acrylate compounds, polyfunctional urethane acrylate compounds, or polyfunctional epoxy acrylate compounds, or Thermally polymerizable curable compounds such as alkoxysilanes and alkylalkoxysilanes are preferred.

The curable resin composition forming the hard coat layer may contain a leveling agent as a surface conditioning component. Examples of the leveling agent include fluorine leveling agents, silicone leveling agents and acrylic leveling agents. Among these leveling agents, an acrylic leveling agent is preferable because excellent adhesion can be ensured when the first barrier layer is laminated on the surface of the hard coat layer.

A photopolymerization initiator is used when the curable resin composition is cured with ultraviolet rays. Examples of the photopolymerization initiator include benzyl, benzophenone and derivatives thereof, thioxanthones, benzyldimethylketals, α-hydroxyalkylphenones, hydroxyketones, aminoalkylphenones and acylphosphine oxides. The amount of the photopolymerization initiator added is usually 0.1 to 8 parts by mass with respect to 100 parts by mass of the curable resin composition.

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 refractive index adjusting component such as fine particles of a high refractive index metal compound such as zinc oxide, zirconium oxide or titanium oxide, or fine particles of a low refractive index metal compound such as magnesium fluoride. be done. Here, it is preferable that the size of the fine particles of the refractive index adjusting component is 5 to 50 nm, since the transparency and total light transmittance of the hard coat layer are not impaired. Further, the fine particles of the refractive index adjusting component may be mixed in advance with the curable resin composition, and then mixed with the curable resin composition forming the hard coat layer to be included. . Alternatively, the fine particles of the refractive index adjusting component may be mixed in advance with the curable resin composition, and the resulting mixture may be used as the curable resin composition for forming the hard coat layer. As a mixture of fine particles of the refractive index adjusting component and the curable resin composition in advance, there are commercially available products. Such commercially available products include, for example, Lioduras TYZ, Lioduras TYT, and Lioduras TYM (manufactured by Toyochem Co., Ltd.).

The curable resin composition forming the hard coat layer, in addition to the components described above, includes, for example, lubricants such as silicon-based compounds, fluorine-based compounds, or mixed compounds thereof, antioxidants, ultraviolet absorbers, and antistatic agents. , flame retardants such as silicone compounds, fillers, additives such as glass fibers and silica. These additives can be used singly or in combination of two or more.

Although the thickness of the hard coat layer is not particularly limited, it is preferably 1 to 20 μm. When 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 . In addition, when the thickness of the hard coat layer is 20 μm or less, it is possible to further ensure moldability and cuttability of the first resin base material 1 . Furthermore, it is also preferable in that curing shrinkage of the hard coat layer is further suppressed, so that warpage and undulation of the first resin base material 1 are prevented.

When the refractive index of the first resin substrate 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 is preferably within the range of na±0.15. More preferably within the range of 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 8 for image display is improved, and color unevenness can be further prevented.

As a method for forming the hard coat layer, for example, after coating the surface of the first resin substrate 1 as a coating of a curable resin composition, it is formed into a cured film, so that the surface of the first resin substrate 1 Examples include, but are not limited to, forming and laminating methods.
A known method is used as a lamination method with the first resin base material 1 . Examples of the known methods include dip coating, natural coating, reverse coating, comma coating, roll coating, spin coating, wire bar coating, extrusion, curtain coating, spray coating and gravure coating. coat 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 may be employed.
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 in advance on the surface of the first resin base material 1 .

[Method for producing light guide plate for image display]
As an example of the method for manufacturing the image display light guide plate of the present embodiment, a method for manufacturing the image display light guide plate 8 shown in FIG. 1 will be described.
The first resin base material 1 and the second resin base material 7 are prepared ([base material preparation step]), and the first anchor coat layer 2 and the second A first barrier layer 3 and a second barrier layer 5 are formed via two anchor coat layers 6 ([barrier layer forming step]). As a method for manufacturing the first barrier layer 3 and the second barrier layer 5, an appropriate manufacturing method is selected according to the materials of the first barrier layer 3 and the second barrier layer 5. FIG.
For example, a photosensitive material for forming a hologram is applied to the surface of the first barrier layer 3 in the first resin substrate 1 on which the first barrier layer 3 is formed. At this time, a transparent seal layer having the same thickness as the hologram layer 4 may be provided on the outer peripheral portion of the first barrier layer 3 . The seal layer seals the outer periphery of the hologram layer 4 after the hologram layer 4 is formed from the photosensitive material. The seal layer is made of a transparent material such as epoxy resin, silicone resin or ene-thiol resin.
After that, the second resin base material 7 on which the second barrier layer 5 is formed is placed on the photosensitive material with the second barrier layer 5 facing the photosensitive material ([Production of light guide plate process]).
However, the manufacturing order described above is an example. For example, after the photosensitive material is applied to the second resin substrate 7 having the second barrier layer 5 formed thereon, the first resin substrate 1 having the first barrier layer 3 formed thereon is placed on the hologram layer 4 . may
After that, the first resin base material 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 base material 7 are formed by vacuum pressing. are bonded together to obtain the light guide plate 8 for image display.
After that, interference fringes corresponding to the diffraction pattern are formed on the photosensitive material, and a diffraction grating is formed in the photosensitive material.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Production Examples. However, the present invention is not limited to the embodiments and manufacturing examples described later, and various modifications are possible without departing from the gist of the present invention.

<Example 1>
PMMA (polymethyl methacrylate, trade name "Acrylite (registered trademark), manufactured by Mitsubishi Chemical Corporation) is used as the material of the resin base material. The resin base material is a rectangular plate of width 200 mm x length 200 mm x thickness 1 mm. do.
As a material for the hard coat layer, an acrylic UV curable resin (trade name “Shikou UV1700B”, manufactured by Mitsubishi Chemical Corporation) is used.
As materials for the anchor coat layer, polyester resin 1 (trade name “Vylon 63SS” manufactured by Toyobo Co., Ltd., hydroxyl value: 5 mgKOH/g) and isocyanate compound 1 (trade name “Coronate HX” manufactured by Tosoh Corporation, hexamethylene diisocyanate isocyanurate structure trimer) and NCO (number of isocyanate groups of isocyanate compound 1) / OH (number of hydroxyl groups of polyester resin 1) = 1 (molar ratio) Anchor coating liquid 1 (Table 1 ) is used.
Silicon oxynitride is used as the material of the barrier layer.

Using the above materials, the substrate preparation step and the barrier layer forming step described below are performed to produce a laminate.

(Base material preparation step)
In the base material preparation step, after washing and drying the resin base material, a hard coat layer is formed on the resin base material.
A state in which a resin substrate was cut into a rectangular shape of 200 mm × 200 mm and immersed in a 5% surfactant aqueous solution of a neutral detergent (trade name “Semiclean (registered trademark) M-LO”, manufactured by Yokohama Yushi Kogyo Co., Ltd.). for 5 minutes.
Thereafter, the resin substrate is ultrasonically cleaned for 5 minutes while being immersed in ultrapure water. Furthermore, the resin base material is rinsed with ultrapure water, and after air-drying, the resin base material is dried in an oven at 80° C. under a nitrogen atmosphere. After that, the air-dried evaluation sample is washed with UV ozone for 1 minute in a UV ozone washing machine.
Next, an acrylic UV curable resin, which is a material for the hard coat layer, is applied to both surfaces of the resin substrate with a bar coater, dried at 90 ° C. for 1 minute, and then exposed to an integrated light amount of 500 mJ / cm ² on both surfaces. A 5 μm hard coat layer is provided.

(Barrier layer forming step)
In the barrier layer forming step, a barrier layer is formed on the surface of the hard coat layer via an anchor coat layer.
Anchor coat liquid 1 is applied to the surface of the hard coat layer using a bar coater and dried at 60° C. for 1 minute to provide an anchor coat layer having a thickness of 25 nm.
Silicon oxynitride having a thickness of 130 nm was formed by a reactive sputtering method using silicon (manufactured by Kojundo Chemical Laboratory Co., Ltd.) as a target while supplying oxygen gas, nitrogen gas, and argon gas under the conditions shown in Table 1. film formation is performed.
By the above operations, the laminate of Example 1 consisting of hard coat layer/resin substrate/hard coat layer/anchor coat layer (AC-1, 25 nm)/barrier layer (silicon oxynitride, 130 nm) is obtained.

Table 1 shows the material of the resin substrate (resin substrate material), the material of the hard coat layer (hard coat layer material), the material of the anchor coat layer (AC layer material), and the anchor coat layer of the laminate of Example 1. Molar ratio of the isocyanate group of the isocyanate compound to the hydroxyl group of the binder resin (NCO/OH), film formation pressure of the barrier layer (film formation pressure [Pa]), electric power during film formation (electric power [W]), flow rate of Ar (Ar [sccm]), the flow rate of O ₂ (O ₂ [sccm]) and the flow rate of N ₂ (N ₂ [sccm]), and the thickness of the barrier layer (thickness [nm]).

<Example 2>
In Example 2, acrylic resin 1 (trade name “Acryt 6AN-6000”, manufactured by Taisei Fine Chemical Co., Ltd., hydroxyl value: 108 mgKOH/g) and isocyanate compound 1 are used as materials for the anchor coat layer. Number of isocyanate groups)/OH (number of hydroxyl groups in acrylic resin 1) = 1 (molar ratio) was defined as anchor coating liquid 2 (denoted as "AC-2" in Table 1), and the thickness of the anchor coating layer was A laminate is produced in the same manner as in Example 1 except that the thickness of the barrier layer is 150 nm and the thickness of the barrier layer and the film formation conditions are changed as shown in Table 1.
That is, the laminate of Example 2 is composed of hard coat layer/resin substrate/hard coat layer/anchor coat layer (AC-2, 150 nm)/barrier layer (silicon oxynitride, 100 nm).

Table 1 shows the material of the resin substrate (resin substrate material), the material of the hard coat layer (hard coat layer material), the material of the anchor coat layer (AC layer material), and the anchor coat layer of the laminate of Example 2. Molar ratio of the isocyanate group of the isocyanate compound to the hydroxyl group of the binder resin (NCO/OH), film formation pressure of the barrier layer (film formation pressure [Pa]), electric power during film formation (electric power [W]), flow rate of Ar (Ar [sccm]), the flow rate of O ₂ (O ₂ [sccm]) and the flow rate of N ₂ (N ₂ [sccm]), and the thickness of the barrier layer (thickness [nm]).

<Example 3>
In Example 3, acrylic resin 2 (trade name “Acryt 6BF-400”, manufactured by Taisei Fine Chemicals Co., Ltd., hydroxyl value: 59 mgKOH/g) and isocyanate compound 1 are used as materials for the anchor coat layer. Number of isocyanate groups)/OH (number of hydroxyl groups of acrylic resin 2) = 1 (molar ratio) was defined as anchor coat liquid 3 (denoted as "AC-3" in Table 1), and the thickness of the anchor coat layer was A laminate is produced in the same manner as in Example 1 except that the thickness of the barrier layer is 100 nm and the thickness of the barrier layer and the film formation conditions are changed as shown in Table 1.
That is, the laminate of Example 3 is composed of hard coat layer/resin substrate/hard coat layer/anchor coat layer (AC-3, 100 nm)/barrier layer (silicon oxynitride, 100 nm).

Table 1 shows the material of the resin substrate (resin substrate material), the material of the hard coat layer (hard coat layer material), the material of the anchor coat layer (AC layer material), and the anchor coat layer of the laminate of Example 3. Molar ratio of the isocyanate group of the isocyanate compound to the hydroxyl group of the binder resin (NCO/OH), film formation pressure of the barrier layer (film formation pressure [Pa]), electric power during film formation (electric power [W]), flow rate of Ar (Ar [sccm]), the flow rate of O ₂ (O ₂ [sccm]) and the flow rate of N ₂ (N ₂ [sccm]), and the thickness of the barrier layer (thickness [nm]).

<Comparative Example 1>
In Comparative Example 1, acrylic resin 1 and isocyanate compound 1 were used as materials for the anchor coat layer, and NCO (number of isocyanate groups in isocyanate compound 1)/OH (number of hydroxyl groups in acrylic resin 1) = 0.5 (molar ratio). Anchor coating solution 4 (denoted as “AC-4” in Table 1) was formulated so that to produce a laminate.
That is, the laminate of Comparative Example 1 is composed of hard coat layer/resin substrate/hard coat layer/anchor coat layer (AC-4, 25 nm)/barrier layer (silicon oxynitride, 100 nm).

Table 1 shows the material of the resin substrate (resin substrate material), the material of the hard coat layer (hard coat layer material), the material of the anchor coat layer (AC layer material), and the anchor coat layer of the laminate of Comparative Example 1. Molar ratio of the isocyanate group of the isocyanate compound to the hydroxyl group of the binder resin (NCO/OH), film formation pressure of the barrier layer (film formation pressure [Pa]), electric power during film formation (electric power [W]), flow rate of Ar (Ar [sccm]), the flow rate of O ₂ (O ₂ [sccm]) and the flow rate of N ₂ (N ₂ [sccm]), and the thickness of the barrier layer (thickness [nm]).

<Comparative Example 2>
In Comparative Example 2, acrylic resin 1 and isocyanate compound 1 were blended so that NCO (number of isocyanate groups in isocyanate compound 1)/OH (number of hydroxyl groups in acrylic resin 1) = 0.75 (molar ratio). A laminate is produced in the same manner as in Example 1, except that anchor coating solution 5 (denoted as "AC-5" in Table 1) is used and the thickness of the barrier layer and film formation conditions are changed as shown in Table 1. .
That is, the laminate of Comparative Example 2 is composed of hard coat layer/resin substrate/hard coat layer/anchor coat layer (AC-5, 25 nm)/barrier layer (silicon oxynitride, 100 nm).

Table 1 shows the material of the resin substrate (resin substrate material), the material of the hard coat layer (hard coat layer material), the material of the anchor coat layer (AC layer material), and the anchor coat layer of the laminate of Comparative Example 2. Molar ratio of the isocyanate group of the isocyanate compound to the hydroxyl group of the binder resin (NCO/OH), film formation pressure of the barrier layer (film formation pressure [Pa]), electric power during film formation (electric power [W]), flow rate of Ar (Ar [sccm]), the flow rate of O ₂ (O ₂ [sccm]) and the flow rate of N ₂ (N ₂ [sccm]), and the thickness of the barrier layer (thickness [nm]).

<Measurement and evaluation method>
Methods for measuring and evaluating various physical property values of laminates obtained in Examples and Comparative Examples will be described.

(Elemental composition of barrier layer)
For the laminates of Examples and Comparative Examples, an X-ray photoelectron spectrometer (K-Alpha, manufactured by Thermo Fisher Scientific) was used to measure the binding energy by XPS (X-ray photoelectron spectroscopy). , N1S, and C1S to calculate each elemental composition [atm %].

Each elemental composition Measured values of [atm %] are shown.

(solvent resistance)
The solvent resistance test is performed using a friction fastness tester RT-300 manufactured by Daiei Kagaku Seiki Seisakusho. A flat test stand is installed in the testing machine, and the laminates of Examples and Comparative Examples are cut into strips of 2 cm in width and 20 cm in length, which are set on the test stand with the barrier layer facing upward. A piece of wiping cloth (N2325 manufactured by Hashimoto Cloth Co., Ltd.) is set so as to cover the friction surface of the friction element of the testing machine, and a load weight of 800 g is attached to the friction element (a total load of 1 kg of a 200 g friction element and an 800 g weight). Isopropyl alcohol (IPA) was dropped on the barrier layer surface of the strip-shaped laminate, and the friction element was lowered onto the barrier layer surface. and evaluate the solvent resistance according to the following criteria.
◯ (good): No peeling of the barrier layer was observed.
x (por): Peeling of the barrier layer is observed.

The column of "solvent resistance" in Table 2 shows the evaluation results.

(Water vapor barrier property)
Using a water vapor transmission rate measuring device (DELTAPERM, manufactured by Technolox), the laminates of Examples and Comparative Examples were set so that the first barrier layer side faced the detector (the first resin substrate side faced water vapor), A water vapor transmission rate [g/m ² /day] is measured under conditions of a temperature of 40° C. and a relative humidity of 90% RH.

The column of "water vapor transmission rate [g/m ² /day]" in Table 2 shows the measured values of the water vapor transmission rate.

<Explanation of results>
In the laminates of Examples 1 to 3, since the NCO/OH ratio of the anchor coat layer is 0.8 or more, the crosslink density of the anchor coat layer is increased and the resistance to solvents is increased. Detachment of the barrier layer during testing can be suppressed. Since these laminates have a low water vapor transmission rate, they are highly effective in preventing deterioration due to the hologram layer.

<Production Example 1>
An example of manufacturing the image display light guide plate 8 using the laminate of Example 1 is shown below.
As a photosensitive material for forming the hologram layer 4, 100 parts by mass of bisphenol-based epoxy resin JER (registered trademark) 1007 (manufactured by Mitsubishi Chemical Corporation, polymerization degree n = 10.8, epoxy equivalent: 1750 to 2200). and 50 parts by mass of triethylene glycol diacrylate and 5 parts by mass of 4,4′-bis(tert-butylphenyl)iodonium hexafluorophosphate and 0 parts by mass of 3,3′-carbonylbis(7-diethylamino)coumarin and 100 parts by weight of 2-butanone (hereinafter also referred to as "photosensitive material A").

(Light guide plate manufacturing process)
In the light guide plate production process of Production Example 1, the image display light guide plate 8 is produced using two laminates of Example 1. FIG.
A seal layer having a width of 5 mm and a thickness of 5 μm is applied to the periphery of the barrier layer of one laminate.
The seal 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 of the laminate to each other. ) OP-1045K”) is used.
As a result, an intermediate body with a seal layer step having a size of 50 mm×50 mm is formed, which is surrounded by the seal layer.
Thereafter, the photosensitive material A forming the hologram layer 4 is applied onto this intermediate by spin coating. The light-sensitive material A is applied so as to have a thickness of 5 μm after drying.
Thereafter, the other laminate is laminated on the hologram layer 4 via the seal layer so that the barrier layer faces the barrier layer of the seal layer stepped intermediate, and press-bonded under reduced pressure. The conditions for press bonding are an absolute pressure of 5 kPa, a temperature of 70° C., and a press pressure of 0.04 MPa.
After that, a diffraction grating is recorded on the hologram layer 4 that has been press-bonded. In this step, the temperature of the laminate including the hologram layer 4 is kept at 20.degree. The diffraction grating is formed by irradiating the laminate with two laser beams and adjusting the respective irradiation angles and intensities to form interference fringes so as to form a required diffraction pattern. Thereby, a diffraction grating is recorded on the hologram layer 4 .
This diffraction grating diffracts each light in the wavelength regions of red, green, and blue incident as image light incident on the incident portion, and emits the light from the display portion at positions corresponding to the pixels of the image light. It is a diffraction grating.
After that, while the laminate including the hologram layer 4 is kept at 20° C., the entire surface of the laminate is irradiated with ultraviolet light (wavelength: 365 nm, irradiance: 80 W/cm ² ) from one side for 30 seconds. A high-pressure mercury lamp is used as a light source for ultraviolet light.
As a result, the seal layer is cured, and the image display light guide plate 8 of Production Example 1 is produced.

The image display light guide plate of the present invention is useful, for example, in display device applications for VR applications and AR applications, and is useful in display device applications such as head-up displays, wearable displays, and head-mounted displays.

1 first resin substrate 2 first anchor coat layer 3 first barrier layer 4 hologram layer 5 second barrier layer 6 second anchor coat layer 7 second resin substrate 8 light guide plate for image display

Claims (8)

A first laminate comprising a first resin substrate, a first anchor coat layer and a first barrier layer in this order, and a hologram layer, wherein the first anchor coat layer comprises a binder resin having a hydroxyl group and isocyanate. wherein the molar ratio NCO/OH of the isocyanate groups (NCO) of the isocyanate compound to the hydroxyl groups (OH) of the binder resin is 0.8 or more. The image display according to claim 1, wherein the first resin base material contains at least one resin selected from the group consisting of poly(meth)acrylic resins, epoxy resins, cyclic polyolefin resins, and polycarbonate resins. Light guide plate. 3. The light guide plate for image display according to claim 1, wherein the first anchor coat layer contains, as the binder resin, at least one resin selected from the group consisting of an acrylic resin, a urethane resin and a polyester resin. . 4. The light guide plate for image display according to claim 1, wherein the first barrier layer contains an inorganic material. 5. The first barrier layer according to any one of claims 1 to 4, wherein the first barrier layer contains at least one inorganic material selected from the group consisting of silicon oxide, silicon oxynitride, diamond-like carbon and aluminum oxide. image display light guide plate. Claims 1 to 5, wherein the first barrier layer contains silicon oxynitride as a main component, and the nitrogen elemental composition in the first barrier layer determined by X-ray photoelectric molecular spectroscopy (XPS) is 7 atm% or more. The light guide plate for image display according to any one of . 7. The light guide plate for image display according to claim 1, wherein the first laminate has first hard coat layers on both surfaces of the first resin base material. 8. The light guide plate for image display according to claim 1, wherein the first laminate has a water vapor transmission rate of less than 0.01 g/m ² /day.

Images