JP2022055332A - Light guide plate for image display - Google Patents

Abstract

To provide a light guide plate for image display that can suppress deterioration of a hologram layer.SOLUTION: A light guide plate for image display 8 has: a first laminate 11 sequentially having a first resin substrate 1 and a first protective layer 3; and a hologram layer 4, in the stated order. The side of the first protective layer 3 in contact with the hologram layer 4 has a surface roughness Sa of less than 5.5 nm.SELECTED DRAWING: Figure 1

Description

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

In the display device, a light guide plate for displaying an image may be 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 by a transparent substrate is used. A hologram having various optical functions such as waveguide, reflection and diffraction is formed on the hologram layer.
As the material used for the hologram material forming the hologram layer, there are many photosensitive compositions containing a radically polymerizable monomer, a base such as a polyhydric acid or an amine, and the like, which may deteriorate the resin base material. In particular, when the resin base material is gradually eroded over a long period of time and the resin base material is deteriorated, the visibility of the light guide plate tends to be deteriorated.

Patent Document 1 describes that a light-sensitive material layer forming a hologram is formed on an optically transparent resin substrate, and the light-sensitive material layer is coated with an aqueous polymer protective barrier. Patent Document 1 suggests that the aqueous polymer protective barrier is provided for the purpose of withstanding the attack by moisture.

Patent Document 2 describes a hologram laminate having a hologram sandwiched between resin substrates via an optical adhesive, and the entire outer peripheral portion thereof is covered with a protective coating layer. Patent Document 2 describes that the protective coating layer may be a coating that enhances airtightness and gas barrier properties.

Japanese Unexamined Patent Publication No. 5-181400 Japanese Unexamined Patent Publication No. 11-184363

However, the technique described in the above patent document 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 aqueous polymer protective barrier.
Therefore, the photosensitive material may erode the resin substrate in a high temperature environment.
Further, since the inside of the resin substrate contains water, the water diffuses into the light-sensitive material layer through the contact surface with the light-sensitive material layer. In addition, since the substrate is exposed to the outside, moisture continues to permeate the substrate from the outside. As a result, moisture permeates the photosensitive material layer via the resin substrate, and even if the moisture is shielded by the aqueous polymer protective barrier, the photosensitivity material layer deteriorates over time due to the moisture from the substrate side. I can't control that.
In the technique described in Patent Document 2, the entire outer periphery of the laminate including the hologram is sealed by the protective coating layer. Therefore, it is possible to prevent the hologram from deteriorating due to the permeation of moisture from the outside of the hologram laminate to the inside. However, the water contained in the resin substrate when the protective coating layer is formed is trapped inside the protective coating layer. As a result, the moisture contained in the resin substrate permeates the hologram, which may cause the hologram to deteriorate over time. In particular, in a high temperature environment, the influence of water release from the resin substrate becomes remarkable.

An object of the present invention is to provide a light guide plate for image display capable of suppressing deterioration of the hologram layer.

As a result of various studies on the laminated structure of the light guide plate for image display, the present inventors provided a protective layer between the resin base material and the hologram layer, and reduced the surface roughness on the side of the protective layer in contact with the hologram layer. By doing so, it was found that the water vapor barrier property can be improved and the deterioration of the hologram layer due to moisture can be suppressed, and the present invention has been completed.
That is, the present invention has the following aspects.

[1] An image display in which a laminate having a resin base material and a protective layer in this order and a hologram layer are arranged in this order, and the surface roughness Sa of the protective layer on the side in contact with the hologram layer is less than 5.5 nm. Light guide plate for.
[2] The light guide plate for image display according to [1], wherein the resin base material contains one or more resins selected from the group consisting of an acrylic resin, a polycarbonate resin, a polyester resin, and a cycloolefin resin. ..
[3] The light guide plate for image display according to [1] or [2], wherein the resin base material includes a resin layer (A) containing a hard resin (a) having a rigid dispersed phase in a matrix.
[4] The image display according to [3], wherein the resin base material is formed by laminating the resin layer (A) and the resin layer (B) having a main component different from that of the resin layer (A). Light guide plate for.
[5] The light guide plate for image display according to any one of [1] to [4], wherein the thickness of the resin base material is 0.05 to 5 mm.
[6] The image display according to any one of [1] to [5], wherein the pencil hardness on the surface of the resin substrate opposite to the surface facing the protective layer is 3H or more. Light guide plate.
[7] The light guide plate for image display according to any one of [1] to [6], wherein the laminated body has an adhesive layer between the resin base material and the protective layer.

According to the present invention, it is possible to provide a light guide plate for image display capable of suppressing deterioration of the hologram layer.

It is a schematic cross-sectional view which shows an example of the light guide plate for image display of this invention.

Hereinafter, an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described later, and various modifications can be made as long as the gist of the present invention is not deviated.

<Light guide plate for image display>
The light guide plate for image display of the present embodiment has at least a laminate provided with a resin base material and a protective layer, and a hologram layer. The resin base material, the protective layer, and the hologram layer are arranged in this order in the thickness direction. The resin base material and the protective 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 laminates are arranged on both surfaces of the hologram layer, the laminate arranged on one surface of the hologram layer is called the first laminate, and the laminate arranged on the other surface of the hologram layer is called the second laminate. It is called the body. In this case, the hologram layer is sandwiched between the first protective layer of the first laminated body and the second protective layer of the second laminated body, and the other surface of the first protective layer has a first resin group. The materials are laminated, and the second resin base material is laminated on the other surface of the second protective layer. In the present embodiment, the first laminated body and the second laminated body may be collectively referred to hereinafter simply as "laminated body". The first resin base material and the second resin base material may be collectively referred to hereinafter simply as "resin base material". In addition, the first protective layer and the second protective layer may be collectively referred to hereinafter simply as "protective layer".

One or more transparent layers may be arranged between the resin base material and the protective layer, and between the protective layer and the hologram layer. Examples of the transparent layer include an adhesive layer and a hard coat layer.
Further, the protective layer and the transparent layer may be arranged on one surface of the resin base material, but may be arranged on both surfaces of the resin base material. That is, the protective layer, the resin base material, the protective layer and the hologram layer are arranged in this order in the thickness direction, or the protective layer, the transparent layer, the resin base material, the transparent layer, the protective layer and the hologram layer are arranged in this order in the thickness direction. It may be configured to be arranged in order.

The light guide plate for image display has an incident portion for incident image light and a display unit for displaying an image by the image light. The hologram layer is arranged between the incident portion and the display portion. The hologram layer is formed with a diffraction grating pattern for waveguideing at least the image light incident from the incident portion to the display portion and emitting the image light from the display portion. The diffraction grating pattern in the display unit transmits at least a part of the external light incident from the outside of the light guide plate for image display. The external light is incident from the surface opposite to the display unit.

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, as a result of the external light also passing through the resin base material and the display unit, the observer of the display unit can observe both the image light and the external light in the visual field.
The light guide plate for image display of the present embodiment is suitably used for display devices and the like using VR (virtual reality) technology or AR (augmented reality) technology, and in particular, for in-vehicle displays and sports sunglasses to be used outdoors. It can be suitably used.
Further, the light guide plate for image display of the present embodiment is typified by a combiner of a head-up display (HUD, Head-Up Display) mounted on an automobile and a reflector for a reflective liquid crystal display device, in addition to the display application. It may be used in a device such as a hologram optical element (HOE, Holographic Optical Element).

Hereinafter, a detailed configuration of an example of the image display light guide plate of the present embodiment will be described based on the example shown in FIG. 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, in the thickness direction, the first resin base material 1, the first adhesive layer 2, the first protective layer 3, the hologram layer 4, the second protective layer 5, and the second adhesive layer 6 are used. And the second resin base material 7 are arranged in this order.
The plan view shape of the light guide plate 8 for image display is not particularly limited. For example, the light guide plate 8 for image display may be shaped into a shape that can be attached to the display device used.
For example, the light guide plate 8 for image display may be a rectangular plate having a shape larger than the shape attached to the display device. In this case, the light guide plate 8 for image display is formed by being cut into a shape that can be attached to the display device before being assembled to the display device.
The light guide plate 8 for image display may have a flat plate shape or, if necessary, a curved plate shape.
Hereinafter, an example will be described in which the light guide plate 8 for image display is made of a flat plate having a rectangular shape in a plan view.

<< First laminated body 11 >>
The first laminated body 11 includes a first resin base material 1 and a first protective layer 3 in this order. The first laminated body 11 may have a first adhesive layer 2 between the first resin base material 1 and the first protective layer 3. The image display light guide plate 8 can suppress deterioration of the hologram layer by arranging the first laminated body 11 on the surface of the hologram layer 4.

(Barrier)
The water vapor permeability of the first laminated body 11 is preferably less than 1 g / m ² / day, more preferably less than 0.5 g / m ² / day, still more preferably less than 0.3 g / m ² / day, and 0.1 g. Less than / m ² / day is even more preferred, less than 0.08 g / m ² / day is even more preferred, and less than 0.05 g / m ² / day is even more preferred.
When the water vapor transmittance of the first laminated body 11 is within the above range, deterioration of the hologram layer 4 can be further suppressed.

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

The thickness of the first resin base material 1 is not particularly limited, but is preferably 0.05 to 5 mm.
The lower limit of the thickness of the first resin base material 1 is not particularly limited, but from the viewpoint of improving scratch resistance, 0.1 mm or more is preferable, and 0.2 mm or more is more preferable.
The upper limit of the thickness of the first resin base material 1 is not particularly limited, but is preferably 3 mm or less, more preferably 2 mm or less, from the viewpoint of improving molding processability and total light transmittance.
In the present specification, the thickness of the first resin base material 1 can be measured by a dial gauge type using a stylus, a micrometer, or the like.

The pencil hardness of the surface of the first resin base material 1 on the side opposite to the side facing the first protective layer 3 (hereinafter, also simply referred to as "pencil hardness on the surface of the first resin base material 1") is particularly limited. However, 3H or more is preferable, 4H or more is more preferable, and 5H or more is further preferable. Since the pencil hardness of the surface of the first resin base material 1 is high (high hardness), excellent scratch resistance can be imparted to the light guide plate 8 for image display.

Further, the surface roughness Sa of the first resin base material 1 on the side facing the first protective layer 3 (hereinafter, also simply referred to as “surface roughness Sa of the first resin base material 1”) is not particularly limited. However, it is preferably less than 5.5 nm. Since the surface roughness Sa of the first resin base material 1 is small, the first protective layer 3 described later is likely to be formed more uniformly, and the surface roughness Sa of the first protective layer 3 is also smaller. As a result, the water vapor barrier property of the first protective layer 3 becomes better, and deterioration of the hologram layer 4 can be suppressed. From this point of view, the surface roughness Sa of the first resin base material 1 is preferably less than 5.5 nm, more preferably 5.0 nm or less, further preferably 4.5 nm or less, still more preferably 4.0 nm or less, with 0 nm as the lower limit. More preferably, 3.0 nm or less is even more preferable, 2.5 nm or less is even more preferable, 2.0 nm or less is even more preferable, and 1.5 nm or less is particularly preferable.
In the present specification, the surface roughness Sa is the surface roughness measured by using a white interferometer (VertScan, manufactured by Ryoka System Co., Ltd.).

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. When the total light transmittance of the first resin base material 1 is 80% or more, the brightness value of the light guide plate 8 for image display becomes better.

The first resin base material 1 preferably contains a thermoplastic resin from the viewpoint of improving optical properties, impact resistance, scratch resistance and molding processability.
The thermoplastic resin is not particularly limited as long as it is a thermoplastic resin capable of forming a film, a sheet or a plate by melt extrusion. Preferred examples of thermoplastic resins are aromatic polyesters such as polyethylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, polybutylene terephthalate, poly-1,4-cyclohexylene methylene terephthalate; and aliphatic polyesters such as polylactic polymers. Representative polyester-based resins; Polypolymer-based resins such as polyethylene, polypropylene, cycloolefin-based resins; Polycarbonate-based resins, acrylic resins, polystyrene-based resins, polyamide-based resins, polyether-based resins, polyurethane-based resins, polyphenylene sulfide-based resins , Polyesteramide resin, polyether ester resin, vinyl chloride resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, modified polyphenylene ether resin, polyallylate resin, polysulfone resin, polyether Examples thereof include imide-based resins, polyamideimide-based resins, polyimide-based resins, and copolymers thereof. These thermoplastic resins can be used alone 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 kinds of materials selected from the group consisting of the above thermoplastic resins are laminated.
In the present invention, one or more selected from the group consisting of acrylic resins, polycarbonate resins, polyester resins and cycloolefin resins is preferable from the viewpoint of almost no absorption in the visible light region.
Among these, acrylic resins are preferable from the viewpoint of excellent transparency, scratch resistance and molding processability.
Further, a polycarbonate resin is preferable from the viewpoint of excellent transparency, impact resistance and molding processability.

(Acrylic resin)
Examples of the monomer constituting the acrylic resin include methyl methacrylate, methacrylic acid, acrylic acid, benzyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, and t-butyl. (Meta) 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, dicyclopentenyl Oxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, acrylic (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- (meth) acroyloxyethyl succinate, 2- (meth) acro of maleic acid Iloxyethyl, 2- (meth) acroyloxyethyl phthalate, 2- (meth) aclioil oxyethyl hexahydrophthalic acid, pentamethylpiperidyl (meth) acrylate, tetramethylpiperidyl (meth) acrylate, dimethylaminoethyl ( Examples thereof include meth) acrylate and diethylaminoethyl (meth) acrylate. These may be polymerized alone and used, or two or more kinds may be polymerized and used.

Further, other monomers copolymerizable with the monomers constituting the acrylic resin may be added. The other monomer may be a monofunctional monomer, that is, a compound having one polymerizable carbon-carbon double bond in the molecule, or a polyfunctional monomer, that is, polymerized in the molecule. It may be a compound having at least two sex carbon-carbon double bonds.
Here, as an example of the monofunctional monomer, aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyltoluene; alkenyl cyanide compounds such as acrylonitrile and methacrylonitrile; acrylic acid, methacrylic acid and maleic anhydride, Examples thereof include N-substituted maleimide.
Examples of polyfunctional monomers include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate, and trimethylolpropane triacrylate; allyl acrylate, allyl methacrylate, and silica skin. Alkenyl esters of unsaturated carboxylic acids such as allyl acid; polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate, triallyl cyanurate, triallyl isocyanurate; aromatic polyalkenyl compounds such as divinylbenzene. Be done.
The monofunctional monomer and the polyfunctional monomer may be used alone or in combination of two or more.

As the acrylic resin, a methyl methacrylate-styrene copolymer is preferable from the viewpoint of improving environmental resistance (warping due to moisture absorption).
The methyl methacrylate-styrene copolymer resin preferably has 30 to 95% by mass of methyl methacrylate units and 5 to 70% by mass of styrene units, and 40 to 95% by mass of methyl methacrylate units, based on all monomer units. %, Those having 5 to 60% by mass of styrene units are more preferable, and those having 50 to 90% by mass of methyl methacrylate units and 10 to 50% by mass of styrene units are further preferable. When the ratio of the methyl methacrylate unit is at least the above lower limit, the strength and surface hardness of the first resin base material 1 become good, and a light guide plate for image display having good scratch resistance can be obtained. On the other hand, when the ratio of the methyl methacrylate unit is not more than the above upper limit, the environmental resistance is improved.

The acrylic resin can be produced by polymerizing the above-mentioned monomer component by a known method such as suspension polymerization, emulsion polymerization or bulk polymerization.

(Polycarbonate resin)
The polycarbonate-based resin is not particularly limited, and aromatic polycarbonate, aliphatic polycarbonate, or alicyclic polycarbonate can be used.

Examples of the aromatic polycarbonate include those obtained by reacting i) a dihydric phenol with a carbonylating agent by an interfacial transesterification method or a melt transesterification method, and ii) a carbonate prepolymer by a solid phase transesterification method or the like. Examples thereof include those obtained by polymerizing in (iii), a cyclic carbonate compound obtained by polymerizing by a ring-opening polymerization method, and the like. Among these, those obtained by reacting i) a divalent phenol with a carbonylating agent by an interfacial transesterification method, a molten transesterification method, or the like are preferable in terms of productivity.

Examples of the divalent phenol in i) include hydroquinone, resorcinol, 4,4'dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, and bis {(4-hydroxy-3,5-dimethyl) phenyl} methane, 1 , 1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) propane (commonly known as bisphenol A), 2, 2-Bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dimethyl) phenyl} propane, 2,2-bis {(4-hydroxy-3) , 5-Dibromo) Phenyl} propane, 2,2-bis {(3-isopropyl-4-hydroxy) phenyl} propane, 2,2-bis {(4-hydroxy-3-phenyl) phenyl} propane, 2,2 -Bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3-methylbutane, 2,2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,4-bis (4-Hydroxyphenyl) -2-methylbutane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxy) Phenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 9,9-bis (4-hydroxyphenyl) Hydroxyphenyl) fluorene, 9,9-bis {(4-hydroxy-3-methyl) phenyl} fluorene, α, α'-bis (4-hydroxyphenyl) -o-diisopropylbenzene, α, α'-bis (4) -Hydroxyphenyl) -m-diisopropylbenzene, α, α'-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantan, 4,4 '-Dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfooxide, 4,4'-dihydroxydiphenylsulfide, 4,4'-dihydroxydiphenylketone, 4,4'-dihydroxydiphenylether, 4,4'-dihydroxydiphenylester, etc. Can be mentioned. These divalent phenols can be used alone or in combination of two or more.

Among the above-mentioned divalent phenols, bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2 -Bis (4-hydroxyphenyl) -3-methylbutane, 2,2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,2-bis (4 hydroxyphenyl) -4-methylpentane, 1, Divalent phenol selected from the group consisting of 1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene alone or 2 It is preferable to use more than seeds.
Among these, bisphenol A alone or 1,1-bis (4 hydroxyphenyl) -3,3,5-trimethylcyclohexane and bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) It is preferably used in combination with one or more dihydric phenols selected from the group consisting of phenyl} propane and α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene.

Examples of the carbonylating agent in i) include carbonyl halides such as phosgene, carbonate esters such as diphenyl carbonate, and haloformates such as dihaloformates of divalent phenols. These carbonylating agents may be used alone or in combination of two or more.

<Preferable Embodiment of First Resin Base Material 1>
The first preferred embodiment of the first resin base material 1 comprises a resin layer (A) containing a hard resin (a) having a rigid dispersed phase in the matrix.
In the second preferred embodiment of the first resin base material 1, the resin layer (A) containing the hard resin (a) having a rigid dispersed phase in the matrix and the resin layer (A) have different main components. It is formed by laminating the resin layer (B).

(Resin layer (A))
The hard resin (a) forming the resin layer (A) includes a matrix resin and a rigid dispersed phase (hereinafter, also referred to as “hard dispersed phase”).
By forming the resin layer (A) with the hard resin (a), the scratch resistance of the first resin base material 1 can be improved.
Further, by being formed of the hard resin (a), the surface roughness of the resin layer (A) can be reduced. Therefore, since the surface roughness Sa of the first protective layer 3, which will be described later, becomes small, the water vapor barrier property becomes good, and deterioration of the hologram layer 4 can be suppressed.
As the matrix resin of the resin layer (A), one or more selected from the group consisting of the above-mentioned acrylic resin, polycarbonate resin, polyester resin and cycloolefin resin is preferable.
Among these, acrylic resins are preferable because they are excellent in transparency, scratch resistance and molding processability.

The hard dispersed phase contained in the hard resin (a) forming the resin layer (A) may be one having at least one of heat resistance and scratch resistance superior to that of the acrylic resin, and is particularly thermosetting. Sexual resin is preferable.

Examples of the thermosetting resin include polycondensation or addition condensation resins such as phenol resins, amino resins, epoxy resins, silicone resins, thermosetting polyimide resins, and thermosetting polyurethane resins, as well as thermosetting resins. Examples thereof include addition polymerization resins obtained by radical polymerization of unsaturated monomers such as acrylic resins, vinyl ester resins, unsaturated polyester resins, and diallyl phthalate resins. These thermosetting resins can be used individually by 1 type or in combination of 2 or more types.
Among these, if the unsaturated monomer is polyfunctional, it is preferable because the characteristics of a hard material (insoluble in acrylic resin, high glass transition temperature) can be obtained by polymerization cross-linking. Examples of unsaturated monomers include polyols and polyesters of acrylic acid and / or methacrylic acid, as well as crosslinkable monomers such as polyaryls and polyvinyl ethers of these polyols.

Specific examples of the unsaturated monomer include trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane ethoxylate (di-, tri-) acrylate, trimethylolpropane diallyl ether, pentaerythritol triallyl ether, and penta. Examples thereof include erythritol tetraallyl ether, di (trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, and mixtures thereof. Among them, as the unsaturated monomer, trimethylolpropane triacrylate (TMPTA) and trimethylolpropane trimethacrylate (TMPTMA) are preferable in consideration of the affinity with the acrylic resin.

From the viewpoint of improving the scratch resistance of the first resin base material 1, the pencil hardness of the hard resin (a) forming the resin layer (A) is preferably 3H or more, more preferably 4H or more, still more preferably 5H or more. ..
Examples of the method for setting the pencil hardness of the hard resin (a) to 3H or more include a method of including a rigid dispersed phase (hereinafter, also referred to as “hard dispersed phase”) in the matrix of the hard resin (a). ..

Examples of the shape of the hard dispersed phase include particulate, spherical, linear, and fibrous, and the spherical shape is preferable from the viewpoint of being easily dispersed evenly in the matrix of the hard resin (a), but the shape is limited to this. It's not a thing.

The particle size of the hard dispersed phase is appropriately set, but is preferably 0.1 to 1000 μm.
When the particle size of the hard dispersed phase is 0.1 μm or more, hardness can be imparted to the hard resin (a). From this point of view, the particle size of the hard dispersed phase is more preferably 0.5 μm or more, further preferably 1 μm or more.
Further, when the particle size is 1000 μm or less, the surface roughness of the resin layer (A) formed of the hard resin (a) can be reduced. Therefore, since the surface roughness Sa of the first protective layer 3, which will be described later, becomes small, the water vapor barrier property becomes good, and deterioration of the hologram layer 4 can be suppressed. From this point of view, the particle size of the hard dispersed phase is more preferably 500 μm or less, further preferably 100 μm or less, and even more preferably 50 μm or less.
The particle size of the hard dispersed phase can be measured, for example, by reading from an SEM image or by an image analysis method.

The blending amount of the hard dispersed phase in the hard resin (a) is preferably 0.1 to 60% by mass of the total mass of the hard resin (a).
When the blending amount of the hard dispersed phase is 0.1% by mass or more of the total mass of the hard resin (a), the hardness can be imparted to the hard resin (a). From this point of view, the blending amount of the hard dispersed phase is more preferably 0.5% by mass or more, and further preferably 1% by mass or more, based on the total mass of the hard resin (a).
Further, when the blending amount of the hard dispersed phase is 60% by mass or less of the total mass of the hard resin (a), the surface roughness of the resin layer (A) formed of the hard resin (a) can be reduced. From this point of view, the blending amount of the hard dispersed phase is more preferably 50% by mass or less of the total mass of the hard resin (a).

The method of including the hard dispersed phase in the hard resin (a) is not particularly limited, and examples thereof include the following methods.
a) A material constituting the hard dispersed phase is added to the matrix resin material of the hard resin (a).
b) Next, when the matrix resin material is melt-kneaded and molded into a predetermined shape, the material constituting the hard dispersed phase is phase-separated and crosslinked to form a hard dispersed phase in the matrix of the hard resin (a). To form.
Alternatively, the material constituting the hard dispersed phase is previously crosslinked and molded into particles or the like, added to the matrix resin material, melt-kneaded, and molded into a predetermined shape to form the hard resin (a). It may be a method of dispersing a rigid dispersed phase in the matrix of.

In addition to the matrix resin and the hard dispersion phase, the hard resin (a) forming the resin layer (A) may contain, for example, a plasticizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a silicone-based compound, or the like. Various additives such as flame retardants, fillers, glass fibers, and impact resistance modifiers may be contained within a range that does not impair the effects of the present invention.

The method for forming the resin layer (A) is not particularly limited as long as it can form a film, sheet or plate, and examples thereof include a melt extrusion molding method, a press molding method, an injection molding method, and a calendar molding method. ..

The thickness of the resin layer (A) forming the first resin base material 1 is not particularly limited, but is preferably 0.05 to 5 mm.
When the thickness of the resin layer (A) is 0.05 mm or more, the effect of improving scratch resistance can be obtained. From this point of view, the thickness of the resin layer (A) is more preferably 0.1 mm or more, further preferably 0.2 mm or more.
Further, when the thickness of the resin layer (A) is 5 mm or less, the molding processability is good. From this point of view, the thickness of the resin layer (A) is more preferably 3 mm or less, further preferably 2 mm or less.

(Resin layer (B))
The main component of the resin layer (B) is different from that of the resin layer (A). By laminating the resin layer (A) and the resin layer (B), the secondary processability such as impact resistance and punching property of the first resin base material 1 is improved.

As the resin layer (B), one or more selected from the group consisting of the above-mentioned acrylic resin, polycarbonate resin, polyester resin and cycloolefin resin is preferable.
Among these, polycarbonate resin is preferable because it is excellent in transparency, impact resistance and molding processability.

The resin layer (B) plays a role of imparting secondary processability such as excellent impact resistance and punching property to the first resin base material 1 by laminating with the resin layer (A). From this point of view, the thickness of the resin layer (B) should be set based on the ratio to the thickness of the resin layer (A) (if there are two or more layers of the resin layer (A), the ratio to the total thickness). Is preferable.
The ratio of the thickness of the resin layer (B) to the total thickness of the resin layer (A) (thickness of the resin layer (B) / total thickness of the resin layer (A)) (hereinafter, also simply referred to as “thickness ratio”) is. Although not particularly limited, 2 or more is preferable, and 4 or more is more preferable. When the thickness ratio is 2 or more, it is possible to impart secondary processability such as excellent impact resistance and punching property to the first resin base material 1.
The thickness ratio is preferably 40 or less, more preferably 20 or less. When the thickness ratio is 40 or less, the deformation and warpage of the first resin base material 1 can be suppressed under the usage environment.

The laminated structure of the resin layer (A) and the resin layer (B) is not particularly limited, but a structure in which the resin layer (A) is laminated on both surfaces of the resin layer (B) is preferable.
If the laminated structure of the resin layer (A) and the resin layer (B) is such that the resin layer (A) is laminated on both sides of the resin layer (B), the resin layer (A) having good scratch resistance can be obtained. Since it is arranged on the surface of the first resin base material 1, the scratch resistance of the first resin base material 1 is improved. Further, if the resin layer (A) is laminated on both sides of the resin layer (B), even if the first resin base material 1 is exposed to a high temperature or a high temperature and high humidity for a long time, the warp and the resin layer (A) are not present. It is preferable because deformation is easily suppressed.

[First Adhesive Layer 2]
From the viewpoint of improving the adhesion between the first resin base material 1 and the first protective layer 3 and improving the water vapor barrier property, the first adhesion is made between the first resin base material 1 and the first protective layer 3. It is preferable to provide the layer 2. The first adhesive layer 2 is not essential as long as the adhesion between the first resin base material 1 and the first protective layer 3 is good.

The material of the first adhesive layer 2 is not particularly limited, and examples thereof include a thermoplastic resin and a curable resin.
Examples of the thermoplastic resin include fluororesins, polyether sulfone resins, polycarbonate resins, acrylic resins, silicone resins, cycloolefin resins, thermoplastic polyimide resins, polyamide resins, and polyamideimide resins. , Polyarylate resin, polysulfone resin, polyetherimide resin, polyether ether ketone resin, polyether silicon resin, polyester resin, polyphenylene sulfide resin and the like.
Examples of the curable resin include acrylic resin, urethane resin, epoxy resin, silicone resin and the like.
Further, the resin composition constituting the first adhesive layer 2 includes a silane coupling agent, a sensitizer, a cross-linking agent, an ultraviolet absorber, a polymerization inhibitor, a surfactant, a filler, a mold release agent and a thermoplastic resin. Additives such as may be added. These additives can be used alone or in combination of two or more.

The total light transmittance of the first adhesive layer 2 is not particularly limited, but is preferably 80% or more, and more preferably 90% or more. When the total light transmittance of the first adhesive layer 2 is 80% or more, the brightness value of the light guide plate 8 for image display is good.

When the average refractive index of the first resin base material 1 and the first protective layer 3 is n1, the refractive index n2 of the first adhesive layer 2 is preferably in the range of n1 ± 0.20, and n1 ± 0. The range of 15 is more preferable, and the range of n1 ± 0.10. When the refractive index n2 of the first adhesive layer 2 is within the range of n1 ± 0.20, the luminance value of the light guide plate 8 for image display becomes good and color unevenness can be prevented.
The refractive index can be measured by, for example, a refractive index measuring device (model 2010 / M prism coupler, manufactured by Metricon Co., Ltd.).

The thickness of the first adhesive layer 2 is not particularly limited, but is preferably 1 to 700 μm.
Above all, the thickness of the first adhesive layer 2 is more preferably 3 μm or more from the viewpoint of improving the adhesive force between the first resin base material 1 and the first protective layer 3.
Further, from the viewpoint of suppressing color unevenness of the light guide plate 8 for image display, the thickness of the first adhesive layer 2 is more preferably 100 μm or less.

As a method for forming the first adhesive layer 2, for example, a resin composition for forming the first adhesive layer 2 is applied to the first resin base material 1, and then the first protective layer 3 is placed on the resin composition to form a laminated body. Then, a method such as pressing, nip-rolling, or heat laminating the laminated body can be mentioned. When the first adhesive layer 2 is made of a curable resin, a curing step may be included in the formation of the first adhesive layer 2.

[First protective layer 3]
The first protective layer 3 is arranged between the first resin base material 1 and the hologram layer 4 described later. In the configuration shown in FIG. 1, the first protective layer 3 is in close contact with the surfaces of the first resin base material 1 and the hologram layer 4.
The first protective layer 3 prevents gas such as water vapor and oxygen permeating from the outside of the light guide plate 8 for image display and the first resin base material 1 from permeating into the hologram layer 4 and deteriorating it.
Therefore, it is preferable that the first protective layer 3 has a smaller oxygen permeability and water vapor permeability.
The oxygen permeability of the first protective layer 3 is preferably 1 cm ³ / m ² · day · atm or less.
The water vapor permeability of the first protective 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 can be measured using, for example, an oxygen permeability measuring device (OX-TRAN 2/21, manufactured by MOCON).
The water vapor permeability is a water vapor permeability measured using a water vapor permeability measuring device (DELTAPERM, manufactured by Tech nolex).

The surface roughness Sa of the first protective layer 3 on the side in contact with the hologram layer 4 is less than 5.5 nm. Since the first protective layer 3 is uniformly formed due to the small surface roughness Sa, the water vapor barrier property is improved and the deterioration of the hologram layer 4 can be suppressed. From this point of view, the surface roughness Sa of the first protective layer 3 on the side in contact with the hologram layer 4 is preferably 5.0 nm or less, more preferably 4.5 nm or less, and further preferably 4.0 nm or less, with 0 nm as the lower limit. preferable.

The first protective 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 protective layer 3 is preferably 1.48 or more, more preferably 1.48 to 3.0. If the first protective layer 3 has a higher refractive index than the first resin base material 1, the light transmitted through the first protective layer 3 and the first resin base material 1 is optically dense. The light emitted from the first protective layer 3 toward the first resin base material 1 is incident on the optically coarse first resin base material 1, and the emission angle of light from the first protective layer 3 toward the first resin base material 1 is the same as that of the first protective layer 3. It increases according to the difference in refractive index from the first resin base material 1. As a result, the FOV (Field of View) in the light guide plate for displaying the image can be expanded.

The thickness of the first protective layer 3 is not particularly limited, but is preferably 10 to 200 μm.
Above all, the thickness of the first protective layer 3 is more preferably 30 μm or more from the viewpoint of improving the mechanical strength and the barrier property of the first protective layer 3.
Further, from the viewpoint of improving optical characteristics such as total light transmittance, the thickness of the first protective layer 3 is more preferably 100 μm or less, further preferably 75 μm or less, and even more preferably 50 μm or less.

The first protective 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 ensuring good barrier properties, the first protective layer 3 preferably contains at least one selected from the group consisting of silicon oxide and silicon nitrogen oxide, and more preferably contains silicon nitrogen oxide. ..

When the first protective layer 3 is made of silicon oxide or silicon nitrogen oxide, the thickness of the first protective layer 3 is preferably 10 to 300 nm.
Above all, from the viewpoint of improving the barrier property of the first protective layer 3, the thickness of the first protective layer 3 is more preferably 20 nm or more.
Further, from the viewpoint of improving the film forming property of the first protective layer 3, the thickness of the first protective layer 3 is more preferably 200 nm or less.

The method for forming the first protective layer 3 with silicon oxide or silicon nitrogen oxide is not particularly limited. For example, the first protective layer 3 can be formed by a conventionally known method such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a plasma CVD method. When the first protective layer 3 is formed of a silicon oxide or a silicon nitrogen oxide, a corona discharge treatment or a low temperature is applied to the formed surface in order to improve the adhesiveness between the formed surface and the silicon oxide or the silicon nitrogen oxide. Surface treatment such as plasma treatment, coating of a silane coupling agent on the film-forming surface, or coating of a mixture of saturated polyester and isocyanate may be performed.
For example, when a thin film of silicon oxide or silicon nitrogen oxide is formed by the vacuum vapor deposition method, silicon, silicon monoxide, silicon dioxide or a mixture thereof is used as an evaporative substance, and 1.0 × 10 ^-3 to 1 .0 × ^10-5 Under vacuum of Torr, heat and evaporate by electron beam, resistance heating or high frequency heating method.
Further, a reaction vapor deposition method performed while supplying oxygen gas can also be adopted.

The silicon oxide or silicon nitrogen oxide forming the first protective layer 3 may contain calcium, magnesium or an oxide thereof as impurities as long as it is 10% by mass or less.

Diamond-like carbon (DLC) is generally an amorphous carbon consisting of a ternary structure consisting of a diamond-like structure, a graphite-like structure, and a polyethylene-like polymer structure containing a hydrogen atom in the structure. It is a material. When a hydrocarbon such as ethylene, acetylene or benzene is used as a carbon source in the production of DLC, it usually has a basically ternary structure containing hydrogen.
DLC is excellent in hardness, lubricity, wear resistance, chemical stability, heat resistance and surface smoothness. Since DLC forms the above-mentioned dense polymer structure, it is also excellent in gas barrier property and water vapor barrier property.

When the first protective layer 3 is formed by DLC, the forming method is not particularly limited. As the DLC coating method, 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 well-known appropriate coating method can be used.

When the first protective layer 3 is made of aluminum oxide, the first protective layer 3 may be formed of, for example, only Al ₂ O ₃ or is selected from the group consisting of Al, AlO and Al ₂ O ₃ . Two or more kinds may be mixed and formed. The atomic number ratio of Al: O in the aluminum oxide layer differs depending on the preparation conditions of the aluminum oxide layer. The aluminum oxide layer that can be used as the first protective layer 3 may contain a trace amount (up to 3% of all components) of other components as long as the barrier performance is not impaired.

When the first protective layer 3 is made of aluminum oxide, the thickness of the first protective layer 3 is preferably 5 to 800 nm.
The method of forming the first protective layer 3 with the aluminum oxide is not particularly limited. For example, as a method for forming the first protective layer 3, a PVD method (physical vapor deposition method) such as a vacuum vapor 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 vapor deposition method, Al, Al ₂ O ₃ , etc. may be used as the vapor deposition source material, and resistance heating, high frequency induction heating, electron beam heating, or the like may be used as the heating method of the vapor deposition source. .. In the vacuum vapor deposition method, oxygen, nitrogen, water vapor or the like may be introduced as the reactive gas, or reactive vapor deposition using means such as ozone addition or ion assist may be used. Further, the film-forming surface may be biased, the temperature of the film-forming surface may be raised, or the film may be cooled. The same applies to other film forming methods such as a PVD method and a CVD method other than the sputtering method and other vacuum vapor deposition methods.

When glass is used as the first protective layer 3, the glass material is, for example, borosilicate glass, non-alkali glass, low alkali glass, soda lime glass, solgel glass, or these glasses are heat-treated or surface-treated. Things etc. can be mentioned. As the glass, non-alkali glass is particularly preferable from the viewpoint of avoiding coloring due to impurities in the glass material.

When glass is used as the first protective layer 3, the thickness of the first protective layer 3 is preferably 10 to 200 μm.
Above all, the thickness of the first protective layer 3 is more preferably 30 μm or more from the viewpoint of improving the mechanical strength and the barrier property of the first protective layer 3.
Further, from the viewpoint of improving optical characteristics such as total light transmittance, the thickness of the first protective layer 3 is more preferably 100 μm or less, further preferably 75 μm or less, and even more preferably 50 μm or less.

When glass is used as the first protective layer 3, the method for forming the first protective layer 3 can be appropriately selected, and for example, a slot down draw method, a fusion method, a float method, or the like can be adopted. Further, as the glass, a commercially available glass may be used as it is, or a commercially available glass may be polished to a desired thickness and used. Examples of commercially available glass include EAGLE2000 (manufactured by Corning), AN100 (manufactured by AGC), OA10G (manufactured by Nippon Electric Glass), D263 (manufactured by Schott) and the like.

[Hologram layer 4]
The hologram layer 4 is arranged on the surface of the surface of the first protective layer 3 opposite to the side facing the first resin base material 1. The hologram layer 4 is appropriately formed with a diffraction grating corresponding to the function that the image display light guide plate 8 should have.

The material of the hologram layer 4 is not particularly limited, and a known hologram-forming resin material can be used.
The material of the hologram layer 4 is, for example, a hologram recording material composed of 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 Patent Laid-Open No. 9-). 62169, JP-A-11-161141, JP-A-2002-310932) and the like.
Specifically, the hologram layer 4 is an epoxy resin such as a bisphenol-based epoxy resin; (meth) acrylate such as triethylene glycol diacrylate; 4,4'-bis (tert-butylphenyl) iodonium hexafluorophosphate or the like. It is preferably formed from a photosensitive material containing a photopolymerization initiator; a wavelength sensitizer such as 3,3'-carbonylbis (7-diethylamino) coumarin; an organic solvent such as 2-butanone.

≪Second laminated body 12≫
The second laminated body 12 includes a second protective layer 5 and a second resin base material 7 in this order. The second laminated body 12 may have a second adhesive layer 6 between the second resin base material 7 and the second protective layer 5. The image display light guide plate 8 can further suppress deterioration of the hologram layer 4 by arranging the second laminated body 12 on the surface of the hologram layer 4 on the side opposite to the side facing the first laminated body 11.

(Barrier)
The water vapor permeability of the second laminated body 12 is preferably less than 1 g / m ² / day, more preferably less than 0.5 g / m ² / day, still more preferably less than 0.3 g / m ² / day, and 0.1 g. Less than / m ² / day is even more preferred, less than 0.08 g / m ² / day is even more preferred, and less than 0.05 g / m ² / day is even more preferred.
When the water vapor transmittance of the second laminated body 12 is within the above range, deterioration of the hologram layer 4 can be further suppressed.

[Second protective layer 5]
The second protective layer 5 is laminated on the opposite side of the first protective layer 3 via the hologram layer 4. As the second protective layer 5, the same configuration as that exemplified in the description of the first protective layer 3 is used. However, the thickness, material, and the like of the second protective layer 5 may be different from those of the first protective layer 3.

[Second adhesive layer 6]
From the viewpoint of improving the adhesion between the second protective layer 5 and the second resin base material 7 and improving the barrier property, the second adhesive layer is formed between the second protective layer 5 and the second resin base material 7. It is preferable to provide 6. The second adhesive layer 6 is not essential as long as the adhesion between the second protective layer 5 and the second resin base material 7 is good.
As the second adhesive layer 6, the same configuration as that exemplified in the description of the first adhesive layer 2 is used. However, the thickness, material, and the like of the second adhesive layer 6 may be different from those of the first adhesive layer 2.

[Second resin base material 7]
The second resin base material 7 is laminated on the surface of the second protective layer 5 with or without the second adhesive layer 6. 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, and the like 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 arranged on the surface of the light guide plate 8 for displaying an image on the external light incident side located opposite to the display image emitting side, the surface hardness is higher than that of the first resin base material 1. Higher materials may be used.

[Light guide plate for image display 8]
The image display light guide plate 8 has a first adhesive layer 2 and a first protective layer 3 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 second protective layer 5 and the second adhesive layer 6 are arranged.
The gas outside the light guide plate 8 for image display permeates the first resin base material 1 and the second resin base material 7 to some extent, or accumulates inside. At this time, water 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 moisture permeating into the first resin base material 1 and the second resin base material 7 from the outside can be shielded by the first protective layer 3 and the second protective layer 5, so that the hologram layer 4 can be shielded. The permeation of water vapor into the hologram layer 4 is suppressed, and deterioration of the hologram layer 4 can be prevented.

Further, 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 of chemical resistance varies depending on the type of resin material. Therefore, the first resin base material 1 and the second resin base material 7 have lower solvent resistance and hologram 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 permeates the first resin base material 1 and the second resin base material 7. Or, 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, the FOV (Field of View) is lowered, and the image is clear. The degree of decrease is likely to occur.
However, according to the configuration of the present embodiment, the first protective layer 3 and the second protective layer 5 are provided between the first resin base material 1 and the second resin base material 7 and the hologram layer 4, respectively. By suppressing the 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]
The light guide plate for image display of the present embodiment has the surface of the first resin base material and the surface of the first resin base material 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 protective layer. / Or a hard coat layer may be provided between the first resin base material and the first protective layer.

The hardcoat layer is preferably formed from a curable resin composition. The curable resin composition is not particularly limited as long as it is cured by irradiating with energy rays such as electron beam, radiation or ultraviolet rays, or by heating, but is not particularly limited, but from the viewpoint of molding time and productivity. Therefore, an ultraviolet curable resin composition is preferable.

Preferred examples of the curable resin constituting the curable resin composition include an acrylate compound, a urethane acrylate compound, an epoxy acrylate compound, a carboxyl group-modified epoxy acrylate compound, a polyester acrylate compound, a copolymer acrylate, an alicyclic epoxy resin, and a glycidyl. Examples thereof include 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, curable resins that impart excellent surface hardness include, for example, radical polymerization curable compounds such as polyfunctional acrylate compounds, polyfunctional urethane acrylate compounds or polyfunctional epoxy acrylate compounds, and alkoxysilanes or alkylalkoxysilanes. Examples thereof include thermosetting compounds such as.

Further, the curable resin composition may be an organic / inorganic hybrid curable resin composition in which an inorganic component is contained in the curable resin. Examples of the organic / inorganic hybrid curable resin composition include those composed of a curable resin composition containing an inorganic component having a reactive functional group in the curable resin. Using an inorganic component having such a reactive functional group, for example, the inorganic component is copolymerized and crosslinked with a radically polymerizable monomer, so that the organic binder simply contains the inorganic component in an organic / inorganic composite. Compared with the radical curable resin composition, it is preferable because it is less likely to undergo curing shrinkage and can exhibit high surface hardness. Further, from the viewpoint of reducing curing shrinkage, an organic / inorganic hybrid curable resin composition containing ultraviolet-reactive colloidal silica as an inorganic component having a reactive functional group is given as a more preferable example.

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, an acrylic-based leveling agent, and the like. Among them, an acrylic leveling agent is preferable as the leveling agent because excellent adhesion can be ensured when the first protective layer is laminated on the surface of the hard coat layer.

When the curable resin composition is cured by ultraviolet rays, a photopolymerization initiator is used. Examples of the photopolymerization initiator include benzyl, benzophenone and its derivatives, thioxanthones, benzyldimethylketals, α-hydroxyalkylphenones, hydroxyketones, aminoalkylphenones, acylphosphine oxides and the like. The amount of the photopolymerization initiator added is generally 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 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, when the size of the fine particles is 5 to 50 nm, it is preferable because the transparency of the hard coat layer and the total light transmittance are not impaired. Further, the fine particles of the refractive index adjusting component, which have been previously mixed with the curable resin composition, may be mixed with the curable resin composition forming the hard coat layer and contained. .. Further, the curable resin composition for forming the hard coat layer may be obtained as it is, in which the fine particles of the refractive index adjusting component are previously mixed with the curable resin composition. There are commercially available products in which the fine particles of the refractive index adjusting component are previously mixed with the curable resin composition. Examples of such commercially available products include Rio Duras TYZ, Rio Duras TYT, and Rio Duras TYM (all manufactured by Toyochem Co., Ltd.).

In addition to the above-mentioned components, the curable resin composition forming the hard coat layer may contain, for example, a lubricant such as a silicon-based compound, a fluorine-based compound or a mixed compound thereof, an antioxidant, an ultraviolet absorber, an antistatic agent, and the like. It may contain a flame retardant such as a silicone compound and an additive such as a filler, glass fiber and silica. These additives may be used alone or in combination of two or more.

The thickness of the hard coat layer is not particularly limited, but 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. Further, when the thickness of the hard coat layer is 20 μm or less, molding processability and cutting property can be ensured for the first resin base material 1. Further, it is also preferable that the curing shrinkage of the hard coat layer is suppressed and the first resin base material 1 does not warp or swell.

When the refractive index of the first resin base material 1 is na, the refractive index nb of the hard coat layer is preferably in the range of na ± 0.20, more preferably in the range of na ± 0.15, and na ± 0. The range of .10 is more preferable. When the refractive index nb of the hard coat layer is in the range of na ± 0.20, the luminance value of the light guide plate 8 for image display is good and color unevenness can be prevented.

As a method for forming the hard coat layer, for example, it is formed on the surface of the first resin base material 1 by applying it to the surface of the first resin base material 1 as a paint of a curable resin composition and then forming it as a cured film. , However, the method is not limited to this method.
A known method is used as the method of laminating with the first resin base material 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. The law etc. can be mentioned. In addition, for example, a method of laminating the hard coat layer on the first resin base material 1 may be adopted by using a transfer sheet in which the hard coat layer is formed on the release layer.
A primer layer may be provided in advance on the surface of the first resin base material 1 for the purpose of improving the adhesion between the hard coat layer and the first resin base material 1.

<Manufacturing method of light guide plate for image display>
As an example of the method for manufacturing the image display light guide plate of the present embodiment, the 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 adhesive layer 2 and the second adhesive layer 2 and the second resin base material 7 are prepared on the surfaces of the first resin base material 1 and the second resin base material 7. The first protective layer 3 and the second protective layer 5 are formed via the adhesive layer 6 ([protective layer forming step]). As a method for producing the first protective layer 3 and the second protective layer 5, an appropriate manufacturing method is selected depending on the materials of the first protective layer 3 and the second protective layer 5.
For example, a photosensitive material for forming a hologram is applied to the surface of the first protective layer 3 in the first resin base material 1 on which the first protective 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 protective layer 3. The sealing layer seals the outer peripheral portion 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, and for example, an epoxy resin, a silicone resin, an en-thiol resin, or the like is used.
After that, the second resin base material 7 on which the second protective layer 5 is formed is placed on the photosensitive material in a state where the second protective layer 5 is directed toward the photosensitive material ([Making a light guide plate]. Process]).
However, the above-mentioned production sequence is an example. For example, after the photosensitive material is applied to the second resin base material 7 on which the second protective layer 5 is formed, the first resin base material 1 on which the first protective layer 3 is formed is placed on the hologram layer 4. You may.
After that, each layer of the first resin base material 1, the first adhesive layer 2, the first protective layer 3, the hologram layer 4, the second protective layer 5, the second adhesive layer 6 and the second resin base material 7 is pressed by a vacuum press. Is bonded together to obtain a light guide plate 8 for displaying an image.
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.

<Explanation of terms>
The term "main component" as used herein includes the meaning of allowing other components to be included as long as it does not interfere with the function of the main component, unless otherwise specified. At this time, although the content ratio of the main component is not specified, the content ratio of the main component (when two or more components are the main components, the total amount thereof) is the content ratio with respect to the total mass of the composition. 50% by mass or more is preferable, 70% by mass or more is more preferable, and 90% by mass or more (including 100% by mass) is further preferable.

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the examples described later, and various modifications can be made without departing from the gist of the present invention.

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

(Pencil hardness on the surface of the resin base material)
The pencil hardness of the surface of the resin base material obtained in Examples and Comparative Examples on the side opposite to the side facing the protective layer was measured according to JIS K 5600-5-4: 1999. The load during the test was 750 gf.

(Surface roughness Sa)
The surface roughness Sa of the resin base material used in Examples and Comparative Examples and the surface roughness Sa on the side in contact with the hologram layer of the protective layer (surface roughness Sa of the protective layer) are measured by using VertScan. bottom.
Equipment: VertScan (manufactured by Ryoka System Co., Ltd.)
Observation conditions Objective lens: 5x wavelength filter: 530white
Measurement mode: wave
Field size: 640 x 480 pixels Scan range: 7 μm (start)
-7 μm (stop)
Lamp aperture aperture: 50%
Contrast: 62%
Brightness: 0%
Analysis conditions Interpolation: Complete surface correction: Quadratic approximation

(Water vapor barrier)
The water vapor barrier property in the laminates of Examples and Comparative Examples was measured using a water vapor permeability measuring device (DELTAPERM, manufactured by Tech nolox).
The first protective layer side of the laminate was set to be the detector side (the first resin base material side was the water vapor exposure side), and the measurement was performed under the conditions of a temperature of 40 ° C. and a relative humidity of 90% RH.

<Example 1>
(Preparation of resin base material A-1)
Acrylic resin (manufactured by Arkema, trade name "Altuglass HT121", matrix resin: methyl methacrylate-methyl acrylate-styrene copolymer, hard dispersed phase: TMPTA-TMPTMA polymerization crosslinked resin, hard dispersed phase diameter; 5 to 10 μm) Was used as it was as the resin composition a-1.
The resin composition a-1 is supplied to the extruder A, melt-kneaded at 240 ° C. in the extruder, then supplied to a T-die for a single layer heated to 250 ° C., extruded into a sheet, and cooled and solidified. A resin substrate A-1 having a thickness of 0.5 mm was obtained.

(Preparation of protective layer E-1)
The resin base material A-1 is cut out into a rectangular shape of 200 mm × 300 mm, and a protective layer E-1 is produced on one surface of the resin base material A-1 via the adhesive layer D-1 by the following operation. , A laminated body composed of a resin base material A-1 / an adhesive layer D-1 / a protective layer E-1 was obtained.
An ethyl acetate solution of an acrylic resin (manufactured by Taisei Fine Chemicals Co., Ltd., trade name "Acryt 6BF-400"), which is a material of the adhesive layer D-1, is applied to one surface of the resin base material A-1 with a bar coater. The adhesive layer D-1 having a thickness of 100 nm was prepared by drying at 60 ° C. for 1 minute. Further, on the surface of the adhesive layer D-1, a protective layer E-1 having a thickness of 100 nm formed of silicon nitrogen oxide was prepared by a reactive sputtering method. The reactive sputtering method was carried out using silicon as a target under a vacuum of 1.0 × 10 ^-1 Pa while supplying oxygen gas, nitrogen gas and argon gas. The total gas flow rate at this time was 70 sccm.
Table 1 shows the materials and thicknesses of the resin base material, the adhesive layer and the protective layer.

(Measurement and evaluation)
Table 1 shows the pencil hardness of the resin base material surface, the surface roughness of the resin base material, and the protective image of the laminate composed of the resin base material A-2 / protective layer E-1 measured and evaluated by the above-mentioned method. Shows surface roughness and water vapor barrier properties.

<Example 2>
(Preparation of resin base material A-1 / B-1 / A-1)
In Example 2, a resin base material A-1 and a resin base material B-1 laminated in the order of A-1 / B-1 / A-1 was used as the resin base material.
As the material of the resin base material A-1, the resin composition a-1 of Example 1 was used.
The material of the resin base material B-1 is a pellet of polycarbonate resin A (manufactured by Sumika Stylon, trade name "CALIBRE301-4") and polycarbonate resin B (manufactured by Sumika Stylon, trade name "SD Polyca SP3030"). ”) And the pellets of polyester resin (manufactured by SK Chemical Co., Ltd., trade name“ SKYGREEN J2003 ”) are mixed at a mass ratio of 55:25:20, and then a twin-screw extruder heated to 260 ° C. is used. The resin composition b-1 pelleted using was used.

The resin composition a-1 and the resin composition b-1 were supplied to extruders A and B, respectively, and were melt-kneaded at 240 ° C. and 260 ° C. in each extruder and then heated to 250 ° C. It is merged with a T-die for 3 layers, extruded into a sheet so as to have a structure of A-1 / B-1 / A-1, cooled and solidified, and has a thickness of 0.8 mm (A-1: 100 μm, B-). A resin base material A-1 / B-1 / A-1 (1: 600 μm) was produced.

(Preparation of protective layer E-1)
The resin base material A-1 / B-1 / A-1 is cut into a rectangular shape of 200 mm × 300 mm, and in the same manner as in Example 1, one of the resin base materials A-1 is placed on the resin base material A-1 via the adhesive layer D-1. A protective layer E-1 was prepared, and a laminated body composed of a resin base material A-1 / B-1 / A-1 / an adhesive layer D-1 / a protective layer E-1 was obtained.
Table 1 shows the materials and thicknesses of the resin base material, the adhesive layer and the protective layer.

(Measurement and evaluation)
In Table 1, the laminate composed of the resin base material A-1 / B-1 / A-1 / adhesive layer D-1 / protective layer E-1 was measured and evaluated by the above-mentioned method, and the surface of the resin base material was measured and evaluated. It shows the hardness of the pencil, the surface roughness of the resin base material, the surface roughness of the protected image, and the water vapor barrier property.

<Example 3>
(Preparation of hard coat layer C-1 / resin base material A-1 / hard coat layer C-1)
In Example 3, the hard coat layer C-1 was laminated on both surfaces of the resin base material A-1.
As the material of the resin base material A-1, the resin composition a-1 of Example 1 was used.
The material of the hard coat layer C-1 is a photopolymerization initiator A (manufactured by BASF, trade name "") with respect to 100 parts by mass of the ultraviolet curable resin composition A (manufactured by Mitsubishi Chemical Co., Ltd., trade name "Shikou UV1700B"). Mix 4 parts by mass of Initirad 184 ") and 0.5 parts by mass of Leveling Agent A (manufactured by Kyoeisha Chemical Co., Ltd., trade name" Polyflow No. 75 ") so that the solid content of these mixtures is 40% by mass. An ultraviolet curable resin composition c-1 dissolved and diluted with PGM (propylene glycol monomethyl ether) was used.

The ultraviolet curable resin composition c-1 is applied to both surfaces of the resin base material A-1 with a bar coater, dried at 90 ° C. for 1 minute, and then both surfaces are exposed with an integrated light intensity of 500 mJ / cm ² to a thickness of 10 μm. The hard coat layer C-1 of the above was provided to obtain a hard coat layer C-1 / a resin base material A-1 / a hard coat layer C-1.

(Preparation of protective layer E-1)
The hard coat layer C-1 / resin base material A-1 / hard coat layer C-1 is cut into a rectangular shape of 200 mm × 300 mm, and an adhesive layer is formed on one of the hard coat layers C-1 in the same manner as in Example 1. A protective layer E-1 is produced via D-1, and a laminate composed of a hard coat layer C-1 / a resin base material A-1 / a hard coat layer C-1 / an adhesive layer D-1 / a protective layer E-1. I got a body.
Table 1 shows the materials and thicknesses of the resin base material, the hard coat layer, the adhesive layer and the protective layer.

(Measurement and evaluation)
In Table 1, the laminate composed of the hard coat layer C-1, the resin base material A-1, the hard coat layer C-1, the adhesive layer D-1, and the protective layer E-1 was measured and evaluated by the above-mentioned method. , Pencil hardness of the surface of the resin base material, surface roughness of the resin base material, surface roughness of the protective image, and water vapor barrier property.

<Example 4>
(Preparation of hard coat layer C-2 / resin base material A-1 / B-1 / A-1 / hard coat layer C-2)
In Example 4, the resin base material A-1 and the resin base material B-1 were laminated in the order of A-1 / B-1 / A-1, and the hard coat layer C-2 was laminated on both surfaces thereof.
The same resin base material A-1 / B-1 / A-1 as in Example 2 was used.
The material of the hard coat layer C-2 is an ultraviolet curable resin composition A (manufactured by Mitsubishi Chemical Co., Ltd., trade name "Shikou UV1700B") and a reactive functional group-containing silica dispersion (manufactured by Nissan Chemical Co., Ltd., trade name "organo silica sol"). PGM-AC-2140Y ”) was mixed so as to have a mass ratio of curable resin: silica = 50:50, and the photopolymerization initiator A (manufactured by BASF) was mixed with 100 parts by mass of the solid content of the mixture. , 4 parts by mass of the trade name "Omnirad 184") and 0.5 part by mass of the leveling agent A ("Polyflow No. 75" manufactured by Kyoeisha Chemical Co., Ltd.) so that the solid content of the mixture becomes 40% by mass. The ultraviolet curable resin composition c-2 dissolved and diluted with PGM (propylene glycol monomethyl ether) was used.

The ultraviolet curable resin composition c-2 is applied to both surfaces of the resin base material A-1 / B-1 / A-1 with a bar coater, dried at 90 ° C. for 1 minute, and then with an integrated light amount of 500 mJ / cm ² . Both surfaces were exposed, and a hard coat layer C-2 having a thickness of 15 μm was provided to obtain a hard coat layer C-2 / resin base material A-1 / B-1 / A-1 / hard coat layer C-2. ..

(Preparation of protective layer E-1)
The hard coat layer C-2 / resin base material A-1 / B-1 / A-1 / hard coat layer C-2 was cut into a rectangular shape of 200 mm × 300 mm, and one of the hard coats was obtained in the same manner as in Example 1. A protective layer E-1 is formed on the layer C-2 via an adhesive layer D-1, and a hard coat layer C-2 / resin base material A-1 / B-1 / A-1 / hard coat layer C- A laminate composed of 2 / adhesive layer D-1 / protective layer E-1 was obtained.
Table 1 shows the materials and thicknesses of the resin base material, the hard coat layer, the adhesive layer and the protective layer.

(Measurement and evaluation)
Table 1 shows the laminate composed of the hard coat layer C-2 / resin base material A-1 / B-1 / A-1 / hard coat layer C-2 / adhesive layer D-1 / protective layer E-1. The pencil hardness of the surface of the resin base material, the surface roughness of the resin base material, the surface roughness of the protective image, and the water vapor barrier property measured and evaluated by the above-mentioned method are shown.

<Example 5>
(Preparation of resin base material A-2)
An acrylic resin plate with a thickness of 1.5 mm (manufactured by Mitsubishi Chemical Corporation, trade name "Acrylite L") was used as the resin base material A-2.

(Preparation of protective layer E-1)
The resin base material A-2 is cut into a rectangular shape of 200 mm × 300 mm, and the protective layer E-1 is provided on one surface of the resin base material A-2 via the adhesive layer D-1 in the same manner as in Example 1. A laminated body composed of a resin base material A-2 / an adhesive layer D-1 / a protective layer E-1 was obtained.
Table 1 shows the materials and thicknesses of the resin base material, the adhesive layer and the protective layer.

(Measurement and evaluation)
Table 1 shows the pencil hardness of the resin base material surface and the surface of the resin base material measured and evaluated by the above-mentioned methods for the laminate composed of the resin base material A-2 / adhesive layer D-1 / protective layer E-1. It shows the roughness, the surface roughness of the protective image, and the water vapor barrier property.

<Comparative Example 1>
(Preparation of resin base material A-2)
An acrylic resin plate with a thickness of 1.5 mm (manufactured by Mitsubishi Chemical Corporation, trade name "Acrylite L") was used as the resin base material A-2.

(Preparation of protective layer E-1)
The resin base material A-2 is cut into a rectangular shape of 200 mm × 300 mm, and the protective layer E-1 is prepared on one surface of the resin base material A-2 by the following operation to prepare the resin base material A-2 / protection. A laminated body composed of layer E-1 was obtained.
On one surface of the resin base material A-2, a protective layer E-1 having a thickness of 100 nm formed of silicon nitrogen oxide was prepared by a reactive sputtering method. The reactive sputtering method was carried out using silicon as a target under a vacuum of 1.0 × 10 ^-1 Pa while supplying oxygen gas, nitrogen gas and argon gas. The total gas flow rate at this time was 70 sccm.
Table 1 shows the materials and thicknesses of the resin base material and the protective layer.

(Measurement and evaluation)
Table 1 shows the pencil hardness of the resin base material surface, the surface roughness of the resin base material, and the protective image of the laminate composed of the resin base material A-2 / protective layer E-1 measured and evaluated by the above-mentioned method. Shows surface roughness and water vapor barrier properties.

<Explanation of results>
In the laminated bodies of Examples 1 to 5, the surface roughness Sa of the protective layer was less than 5.5 nm, and the water vapor barrier property was good. Among them, comparing Examples 1 and 5, the laminate of Example 1 uses a resin layer (A) containing a hard resin (a) having a rigid dispersed phase in a matrix as a resin base material. Therefore, the surface roughness Sa of the resin base material was smaller, and the surface roughness Sa of the protective layer was also smaller, so that the water vapor barrier property was further improved.
Further, since the laminated body of Examples 1 to 4 has a higher pencil hardness on the surface of the resin base material than the laminated body of Example 5, it is also excellent in scratch resistance.

<Manufacturing example 1>
An example of manufacturing the light guide plate 8 for image display using the laminated body of Example 1 is shown below.
The photosensitive material for forming the hologram layer 4 is 100 parts by mass of a 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 weight of triethylene glycol diacrylate, 5 parts by weight of 4,4'-bis (tert-butylphenyl) iodonium hexafluorophosphate, and 3,3'-carbonylbis (7-diethylamino) coumarin. A mixture of 0.5 parts by mass and 100 parts by mass of 2-butanone (hereinafter, also referred to as "photosensitive material A") is used.

(Light guide plate manufacturing process)
In the light guide plate manufacturing step of Production Example 1, the light guide plate 8 for image display is manufactured using the two laminated bodies of Example 1.
A seal layer having a width of 5 mm and a thickness of 5 μm is applied to the peripheral edge of the protective layer of one of the laminated bodies.
The seal layer is made of a transparent material and is not particularly limited as long as it is a material capable of adhering the protective layers of the laminated body to each other. ) OP-1045K ") is used.
As a result, an intermediate having a stepped seal layer having an opening having a size of 50 mm × 50 mm formed by the seal layer is formed.
After that, the photosensitive material A forming the hologram layer 4 is applied onto the intermediate by spin coating. The photosensitive material A is applied so that the thickness after drying is 5 μm.
After that, the other laminated body is laminated on the hologram layer 4 via the seal layer so that the protective layer faces the protective layer of the intermediate with the seal layer step, and is 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, the diffraction grating is recorded on the press-bonded hologram layer 4. In this step, the temperature of the laminate including the hologram layer 4 is maintained at 20 ° C. The diffraction grating is formed by irradiating the laminated body with two laser beams and adjusting the irradiation angle and intensity of each to form interference fringes so that a required diffraction pattern is formed. As a result, the diffraction grating is recorded on the hologram layer 4.
This diffraction grating diffracts each light in the red, green, and blue wavelength regions incident as image light incident on the incident portion, and emits the light from the display unit at a position corresponding to the pixel of the image light for color display. It is a diffraction grating.
After that, with the laminated body containing the hologram layer 4 kept at 20 ° C., ultraviolet light (wavelength 365 nm, irradiance 80 W / cm ² ) is totally irradiated for 30 seconds from the direction of one side of the laminated body. 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 manufactured.

The light guide plate base material of the present invention is made of a resin that is lightweight and has excellent optical properties, impact resistance, and shape processability, and further has excellent pencil hardness and scratch resistance. Therefore, the light guide plate base material is present. The light guide plate for image display using the above is useful for display device applications such as VR and AR applications, and is useful for display device applications such as head-up displays, wearable displays, and head-mounted displays.

1 1st resin base material 2 1st adhesive layer 3 1st protective layer 4 Hologram layer 5 2nd protective layer 6 2nd adhesive layer 7 2nd resin base material 8 Light guide plate for image display 11 1st laminated body 12 2nd laminated body

Claims (7)

A light guide plate for image display in which a laminate having a resin base material and a protective layer and a hologram layer are arranged in this order, and the surface roughness Sa of the protective layer on the side in contact with the hologram layer is less than 5.5 nm. The light guide plate for image display according to claim 1, wherein the resin base material contains one or more resins selected from the group consisting of an acrylic resin, a polycarbonate resin, a polyester resin, and a cycloolefin resin. The light guide plate for image display according to claim 1 or 2, wherein the resin base material includes a resin layer (A) containing a hard resin (a) having a rigid dispersed phase in a matrix. The light guide plate for image display according to claim 3, wherein the resin base material is formed by laminating the resin layer (A) and the resin layer (B) whose main component is different from that of the resin layer (A). .. The light guide plate for image display according to any one of claims 1 to 4, wherein the thickness of the resin base material is 0.05 to 5 mm. The light guide plate for image display according to any one of claims 1 to 5, wherein the pencil hardness on the surface of the resin base material opposite to the surface facing the protective layer is 3H or more. The light guide plate for image display according to any one of claims 1 to 6, wherein the laminated body has an adhesive layer between the resin base material and the protective layer.

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