JP2024106762A - Hologram layer-forming photosensitive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive composition which enables formation of a hologram layer with a superior refractive index modulation amount (Δn).

SOLUTION: A photosensitive composition for forming a hologram layer is provided, the composition comprising a specific radical polymerizable monomer (1), a radical polymerizable monomer (2) other than the radical polymerizable monomer (1), a binder resin, a photopolymerization initiator, and a sensitizing dye.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

This disclosure relates to a photosensitive composition for forming a hologram layer.

A combiner having a pair of substrates and a hologram sheet positioned between the pair of substrates is known. The hologram sheet includes a base material and a hologram layer provided on the base material. For example, Patent Documents 1 and 2 disclose photosensitive compositions for forming a hologram layer.

Japanese Patent Application Publication No. 06-301322 JP 2001-125474 A

Volumetric reflection holograms, such as Lippmann volumetric holograms, have wavelength selectivity and display images by diffracting (reflecting) light of a specific wavelength that is incident at a specific angle of incidence. The brightness of the projected image usually depends on the amount of refractive index modulation (Δn) of the material contained in the hologram layer. In general, the greater the amount of refractive index modulation (Δn), the more the color clarity improves. However, it was difficult to form a hologram layer with a large Δn using conventional photosensitive compositions.

The objective of this disclosure is to provide a photosensitive composition capable of forming a hologram layer with excellent refractive index modulation (Δn).

The photosensitive composition of the present disclosure contains a radical polymerizable monomer (1) represented by the formula (1) described below, a radical polymerizable monomer (2) other than the radical polymerizable monomer (1), a binder resin, a photopolymerization initiator, and a sensitizing dye, and is intended for forming a hologram layer.

According to the present disclosure, it is possible to provide a photosensitive composition capable of forming a hologram layer having an excellent refractive index modulation amount (Δn). By increasing the refractive index modulation amount (Δn), the color clarity of the hologram layer is improved.

FIG. 1 is a schematic cross-sectional view of a hologram recording sheet according to one embodiment. FIG. 2 is a schematic cross-sectional view of a hologram recording sheet according to one embodiment. FIG. 3 is a schematic cross-sectional view of a hologram recording sheet according to one embodiment. FIG. 4 is a schematic cross-sectional view of a hologram sheet according to an embodiment. FIG. 5 is a schematic cross-sectional view of a hologram sheet according to an embodiment. FIG. 6 is a schematic diagram showing a moving body having a head-up display. FIG. 7 is a schematic cross-sectional view of a combiner according to one embodiment.

In this specification, terms such as "sheet," "film," and "plate" are not distinguished from one another solely on the basis of differences in name. In this specification, the normal direction of a sheet-like (film-like, plate-like) member refers to the normal direction to the sheet surface (film surface, plate surface) of the target sheet-like (film-like, plate-like) member.

In the present disclosure, when multiple upper limit candidates and multiple lower limit candidates are listed for a certain parameter, the numerical range of the parameter may be constructed by combining any one of the upper limit candidates and any one of the lower limit candidates. Examples of the above parameters include physical property values, component content ratios, and layer thicknesses. As an example, the description "Parameter B may be A1 or more, A2 or more, or A3 or more. Parameter B may be A4 or less, A5 or less, or A6 or less." will be explained. In this example, the numerical range of parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.

[Photosensitive composition]
The photosensitive composition of the present disclosure contains a radical polymerizable monomer (1) represented by the formula (1) described below, a radical polymerizable monomer (2) other than the radical polymerizable monomer (1), a binder resin, a photopolymerization initiator, and a sensitizing dye. The photosensitive composition may further contain a cationic polymerizable monomer. The photosensitive composition may further contain an organic solvent.

The photosensitive composition is suitable as a material for forming a hologram layer.

<Radical polymerizable monomer (1)>
The radical polymerizable monomer (1) is represented by formula (1).

The symbols in formula (1) have the following meanings.
R ¹ to R ⁴ each independently represent an alkyl group, a cycloalkyl group, an aryl group, or a halogen atom. Examples of the alkyl group include alkyl groups that may have a branch, such as a methyl group, an ethyl group, a propyl group, and an isopropyl group. The number of carbon atoms in the alkyl group may be 1 or more, 6 or less, or 4 or less. Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group. The number of carbon atoms in the cycloalkyl group may be 3 or more, 4 or more, 12 or less, or 8 or less. Examples of the aryl group include aromatic groups that may have a substituent, such as a phenyl group and a tolyl group. The number of carbon atoms in the aryl group may be 6 or more and 12 or less. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, an alkyl group is preferable, and an alkyl group having 1 to 4 carbon atoms and may have a branch is more preferable.

k1 to k4 each independently represent an integer of 0 or more and 5 or less, preferably an integer of 0 or more and 2 or less, more preferably 0 or 1, and further preferably 0. k1 to k4 each represent the number of R ¹ to R ^4. When at least one of k1 to k4 is 2 or more, the corresponding R ¹ to R ⁴ may be the same or different.

n1 and n2 each independently represent an integer of 1 or more, and from the viewpoint of the balance between the refractive index and the solubility in an organic solvent, preferably represent an integer of 1 or more and 4 or less, more preferably represent 1 or 2, and even more preferably represent 1.

^R5 and ^R6 each independently represent an alkanediyl group having 2 to 4 carbon atoms. Examples of the alkanediyl group include an ethane-1,2-diyl group, a propane-1,3-diyl group, a propane-1,2-diyl group, and a butane-1,4-diyl group. Among these, an ethane-1,2-diyl group is preferred.

p1 and p2 each independently represent 0 or an integer of 1 or more, and from the viewpoint of the balance of polymerization reactivity, refractive index, and solubility in organic solvents, preferably represent 0 or an integer of 1 to 5, more preferably represent 0 or an integer of 1 to 3, and particularly preferably represent 0.

^R7 and ^R8 each independently represent a hydrogen atom or a methyl group.

Examples of the radical polymerizable monomer (1) include monomers constituted by any combination of R ¹ to R ⁸ , k1 to k4, n1 and n2, and p1 and p2, and specifically include compounds represented by the following formula:

The radical polymerizable monomer (1) can be synthesized, for example, according to the method described in WO 2017/135123. As the radical polymerizable monomer (1), for example, a commercially available product may be used.

The radical polymerizable monomer (1) is, for example, a compound that can diffuse and move within a photosensitive material layer. The radical polymerizable monomer (1) is a compound that polymerizes due to the action of active radicals generated from a photoradical polymerization initiator by irradiation with light. A photosensitive composition containing the radical polymerizable monomer (1) can form a hologram layer with a more excellent refractive index modulation amount (Δn) and diffraction efficiency than a conventional photosensitive composition containing a fluorene ring-containing polyfunctional (meth)acrylate. Such a hologram layer can diffract image light to display an image with high color clarity and color reproducibility.

The refractive index of the radical polymerizable monomer (1) may be 1.50 or more, 1.55 or more, 1.60 or more, or 1.80 or less. In this specification, the refractive index of the monomer is measured using an Abbe refractometer (Atago Co., Ltd.'s "Multi-wavelength Abbe refractometer DR-M2") at a measurement wavelength of 589 nm and a measurement temperature of 25°C. Specifically, the monomer is dissolved in N-methylpyrrolidone (NMP) to prepare solutions with monomer concentrations of 5 mass%, 10 mass%, and 15 mass%, and the refractive index of each solution is measured using the above-mentioned device and conditions. Next, an approximation curve is derived from the obtained three measured values, and the value obtained by extrapolating this to a monomer concentration of 100 mass% is taken as the refractive index of the monomer.

The photosensitive composition can contain one or more radically polymerizable monomers (1).

<Radical polymerizable monomer (2)>
The radical polymerizable monomer (2) is a radical polymerizable monomer other than the radical polymerizable monomer (1). The radical polymerizable monomer (2) is, for example, a compound that can diffuse and move in the photosensitive material layer. The radical polymerizable monomer (2) is a compound that is polymerized by the action of active radicals generated from a photoradical polymerization initiator by irradiation with light.

The radical polymerizable monomer (2) has, for example, at least one ethylenically unsaturated double bond-containing group. Examples of the ethylenically unsaturated double bond-containing group include a (meth)acryloyl group and a vinyl group.

In this specification, "(meth)acryloyl group" means "acryloyl group" or "methacryloyl group", "(meth)acrylic acid" means "acrylic acid" or "methacrylic acid", "(meth)acrylate" means "acrylate" or "methacrylate", "(meth)acrylic" means "acrylic" or "methacrylic", and similar expressions have similar meanings.

Examples of the radical polymerizable monomer (2) include unsaturated carboxylic acids, as well as esters, thioesters, amides, and salts of unsaturated carboxylic acids. Examples of the unsaturated carboxylic acids include (meth)acrylic acid, crotonic acid, fumaric acid, and maleic acid. Examples of the esters of unsaturated carboxylic acids include (meth)acrylic acid esters. Examples of the thioesters of unsaturated carboxylic acids include (meth)acrylic acid thioesters. Examples of the amides of unsaturated carboxylic acids include amidated products of (meth)acrylic acid.

Examples of the radical polymerizable monomer (2) include (meth)acrylate compounds such as monofunctional (meth)acrylates having one (meth)acryloyl group and polyfunctional (meth)acrylates having two or more (meth)acryloyl groups, as well as thio(meth)acrylate compounds such as monofunctional thio(meth)acrylates having one (meth)acryloyl group and polyfunctional thio(meth)acrylates having two or more (meth)acryloyl groups. The number of (meth)acryloyl groups in the polyfunctional (meth)acrylate may be 10 or less, 8 or less, 6 or less, or specifically 2. The number of (meth)acryloyl groups in the polyfunctional thio(meth)acrylate may be 10 or less, 8 or less, 6 or less, or specifically 2.

Examples of the monofunctional (meth)acrylate include alkyl (meth)acrylates, hydroxyalkyl (meth)acrylates, alicyclic ring-containing monofunctional (meth)acrylates, aromatic ring-containing monofunctional (meth)acrylates, glycol-based monofunctional (meth)acrylates, nitrogen atom-containing monofunctional (meth)acrylates, sulfur atom-containing monofunctional (meth)acrylates, and halides of these monomers.

Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and lauryl (meth)acrylate.

Examples of hydroxyalkyl (meth)acrylates include hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate.

Examples of alicyclic-containing monofunctional (meth)acrylates include cycloalkyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.

In this specification, examples of aromatic rings include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a fluorene ring, a benzotriazole ring, and a dinaphthothiophene ring.

Examples of aromatic ring-containing monofunctional (meth)acrylates include benzene ring-containing monofunctional (meth)acrylates, naphthalene ring-containing monofunctional (meth)acrylates, benzotriazole ring-containing monofunctional (meth)acrylates, and dinaphthothiophene ring-containing monofunctional (meth)acrylates.

Examples of benzene ring-containing monofunctional (meth)acrylates include phenyl (meth)acrylate, triphenylmethyl (meth)acrylate, benzyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, nonylphenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, phenoxybenzyl (meth)acrylate, β-(meth)acryloxyethyl hydrogen phthalate, phenoxypolyethylene glycol (meth)acrylate, 2-(o-phenylphenoxy)ethyl (meth)acrylate, 2-(o-phenylphenoxy)polyethylene glycol (meth)acrylate, and biphenyl-2,2'-dicarboxylic acid (2-(meth)acryloxyethyl) monoester.

Examples of naphthalene ring-containing monofunctional (meth)acrylates include 2-naphthyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, and 2,3-naphthalenedicarboxylic acid ((meth)acryloxyethyl) monoester.

Examples of benzotriazole ring-containing (meth)acrylates include 2-[2'-hydroxy-5'-((meth)acryloyloxymethyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-((meth)acryloyloxyethyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-((meth)acryloyloxypropyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-((meth)acryloyloxyhexyl)phenyl]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-((meth)acryloyloxyethyl)phenyl]-2H-benzotriazole, and 2-[2'-hydroxy-5'-(β-(meth)acryloyloxyethoxy)-3'-tert-butylphenyl]-5-tert-butyl-2H-benzotriazole.

Examples of dinaphthothiophene ring-containing (meth)acrylates include 6-(meth)acryloyloxymethyl dinaphthothiophene and 6-(meth)acryloyloxyethyl dinaphthothiophene.

Examples of glycol-based monofunctional (meth)acrylates include methoxypropylene glycol (meth)acrylate and 2-ethylhexyl carbitol (meth)acrylate.

Examples of the nitrogen atom-containing monofunctional (meth)acrylate include (meth)acrylamide, N-(meth)acryloylmorpholine, and 2-(9-carbazolyl)ethyl (meth)acrylate. Examples of the sulfur atom-containing monofunctional (meth)acrylate include 2-(tricyclo[5.2.10 ^2,6 ]decylthio)ethyl (meth)acrylate.

Examples of the halides of the above monomers include 2,3-dibromopropyl (meth)acrylate, 2,4,6-tribromophenyl (meth)acrylate, and 2-(tricyclo[5.2.10 ^2,6 ]dibromodecylthio)ethyl (meth)acrylate.

Examples of the polyfunctional (meth)acrylate include aliphatic polyfunctional (meth)acrylates and aromatic ring-containing polyfunctional (meth)acrylates.

Examples of aliphatic polyfunctional (meth)acrylates include 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, diethylenedithioglycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate and methylenebis(meth)acrylamide, as well as halides of these monomers, such as dibromoneopentyl glycol di(meth)acrylate.

Examples of aromatic ring-containing polyfunctional (meth)acrylates include benzene ring-containing polyfunctional (meth)acrylates, naphthalene ring-containing polyfunctional (meth)acrylates, phenanthrene ring-containing polyfunctional (meth)acrylates, dinaphthothiophene ring-containing polyfunctional (meth)acrylates, and fluorene ring-containing polyfunctional (meth)acrylates, as well as halides of these monomers.

Examples of benzene ring-containing polyfunctional (meth)acrylates include 1,3-bis[2-(meth)acryloxy-3-phenoxypropoxy]benzene, bisphenol skeleton-containing polyfunctional (meth)acrylates, and biphenyl skeleton-containing polyfunctional (meth)acrylates.

Examples of the bisphenol skeleton-containing polyfunctional (meth)acrylate include:
Bisphenol F compounds such as bis(4-(meth)acryloxyethoxyphenyl)methane, bis(4-(meth)acryloxydiethoxyphenyl)methane, bis(4-(meth)acryloxypolyethoxyphenyl)methane, and bis(4-(meth)acryloxypropoxyphenyl)methane;
Bisphenol A compounds such as 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypolyethoxyphenyl)propane, and 2,2-bis(4-(meth)acryloxypropoxyphenyl)propane;
Bisphenol S compounds such as bis(4-(meth)acryloxyethoxyphenyl)sulfone, bis(4-(meth)acryloxydiethoxyphenyl)sulfone, bis(4-(meth)acryloxypolyethoxyphenyl)sulfone, and bis(4-(meth)acryloxypropoxyphenyl)sulfone; and Other bisphenol-based compounds such as bis(4-(meth)acryloxyethoxyphenyl)biphenylmethane, bis(4-(meth)acryloxydiethoxyphenyl)biphenylmethane, bis(4-(meth)acryloxypolyethoxyphenyl)biphenylmethane, bis(4-(meth)acryloxypropoxyphenyl)biphenylmethane, bis(4-(meth)acryloxyethoxy-3-phenylphenyl)biphenylmethane, bis(4-(meth)acryloxydiethoxy-3-phenylphenyl)biphenylmethane, bis(4-(meth)acryloxypolyethoxy-3-phenylphenyl)biphenylmethane, and bis(4-(meth)acryloxypropoxy-3-phenylphenyl)biphenylmethane;
Examples include:

Examples of biphenyl skeleton-containing polyfunctional (meth)acrylates include 4,4'-bis(2-(meth)acryloxyethoxy)biphenyl, 4,4'-bis(2-(meth)acryloxydiethoxy)biphenyl, 4,4'-bis(2-(meth)acryloxypolyethoxy)biphenyl, 4,4'-bis(2-(meth)acryloxypropoxy)biphenyl, and biphenyl-2,2'-dicarboxylic acid (2-(meth)acryloxyethyl)(3-(meth)acryloxypropyl-2-hydroxy)diester.

Examples of naphthalene ring-containing polyfunctional (meth)acrylates include naphthalene diol di(meth)acrylate and 2,3-naphthalene dicarboxylic acid (2-(meth)acryloxyethyl) (3-(meth)acryloxypropyl-2-hydroxy) diester. Examples of phenanthrene ring-containing polyfunctional (meth)acrylates include phenanthrene diol di(meth)acrylate and 4,5-phenanthrene dicarboxylic acid (2-(meth)acryloxyethyl) (3-(meth)acryloxypropyl-2-hydroxy) diester.

Examples of dinaphthothiophene ring-containing polyfunctional (meth)acrylates include 2,12-di(meth)acryloyloxymethyldinaphthothiophene and 3,11-di(meth)acryloyloxymethyldinaphthothiophene.

Examples of fluorene ring-containing polyfunctional (meth)acrylates include 9,9-bis(4-(meth)acryloyloxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxymethoxyphenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxypropoxy)phenyl)fluorene, and 9,9-bis(4-(3-(meth)acryloyloxypropoxy)phenyl)fluorene. fluorene, 9,9-bis(4-(meth)acryloyloxydimethoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydiethoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydipropoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytrimethoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytriethoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydipropoxyphenyl)fluorene, tripropoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetramethoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetraethoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetrapropoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxymethoxy-3-methylphenyl)fluorene , 9,9-bis(4-(2-(meth)acryloyloxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxypropoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(3-(meth)acryloyloxypropoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydimethoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydiethoxy-3-methylphenyl)fluorene, fluorene, 9,9-bis(4-(meth)acryloyloxydipropoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytrimethoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytriethoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytripropoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetrameth 9,9-bis(4-(meth)acryloyloxytetraethoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetrapropoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetrapropoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxymethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxyethoxy-3-methylphenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxypropoxy)-3-ethylphenyl)fluorene, 9,9-bis(4-(3-(meth)acryloyloxypropoxy)-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydimethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydiethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydiethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytrimethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytriethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytripropoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetramethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytripropoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetramethoxy-3-ethylphenyl)fluorene, (meth)acryloyloxytetraethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetrapropoxy-3-ethylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxymethoxy-3-propylphenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxyethoxy)-3-propylphenyl)fluorene, 9,9- Bis(4-(2-(meth)acryloyloxypropoxy)-3-propylphenyl)fluorene, 9,9-bis(4-(3-(meth)acryloyloxypropoxy)-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydimethoxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydiethoxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydipropoxy-3-propylphenyl)fluorene phenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytrimethoxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytriethoxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytripropoxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetramethoxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetramethoxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetrapropoxy-3-propylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxy-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxymethoxy-3-phenylphenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-(meth)acryloyloxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(3-(meth)acryloyloxypropoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydimethoxy-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydiethoxy-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxydipropoxy-3-phenylphenyl)fluorene, 9,9 -bis(4-(meth)acryloyloxytrimethoxy-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytriethoxy-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytripropoxy-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetramethoxy-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetraethoxy-3-phenylphenyl)fluorene phenyl)fluorene, 9,9-bis(4-(meth)acryloyloxytetrapropoxy-3-phenylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxy-(2-hydroxy)propoxyphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxy-(2-hydroxy)propoxy-3-methylphenyl)fluorene, 9,9-bis(4-(meth)acryloyloxy-(2-hydroxy)propoxyethoxyphenyl)fluorene, bisphenol fluorene dihydroxy(meth)acrylate, i.e., (meth)acrylic acid adduct of glycidyl ether of 9,9-bis(4-hydroxyphenyl)fluorene, bisphenol fluorene di(meth)acrylate, bisphenoxyethanol fluorene di(meth)acrylate, bisphenoxyethanol fluorene diepoxy(meth)acrylate, bisphenol fluorene diepoxy(meth)acrylate, biscresol fluorene diepoxy(meth)acrylate.

Examples of halogenated monomers include 1,3-bis[2-(meth)acryloxy-3-(2,4,6-tribromophenoxy)propoxy]benzene, bis(4-(meth)acryloxyethoxy-3,5-dibromophenyl)methane, 2,2-bis(4-(meth)acryloxyethoxy-3,5-dibromophenyl)propane, and bis(4-(meth)acryloxyethoxy-3,5-dibromophenyl)sulfone.

(Meth)acrylate compounds also include epoxy (meth)acrylates, urethane (meth)acrylates, polyol (meth)acrylates, and polyester (meth)acrylates.

Examples of thio(meth)acrylate compounds include compounds in which "(meth)acrylate" has been changed to "thio(meth)acrylate" in the names of the (meth)acrylate compounds listed above, or compounds in which "(meth)acryloyloxy" or "(meth)acryloxy" has been changed to "(meth)acryloylthio". Specific examples include triphenylmethylthio(meth)acrylate, S-(1-naphthylmethyl)thio(meth)acrylate, and naphthalenedithiol di(meth)acrylate.

Examples of the radical polymerizable monomer (2) include vinyl monomers. Examples of the vinyl monomers include aromatic ring-containing vinyl monomers and vinyl ester monomers. Examples of the aromatic ring-containing vinyl monomers include styrene-based monomers such as styrene, 2-bromostyrene, and α-methylstyrene; vinylnaphthalene, vinylanthracene, vinylphenanthrene, vinyldinaphthothiophene, divinylbenzene, divinylnaphthalene, and divinyldinaphthothiophene. Examples of the vinyl ester monomers include vinyl acetate and vinyl propionate.

The refractive index of the radical polymerizable monomer (2) may be 1.40 or more, 1.45 or more, 1.50 or more, 1.55 or more, 1.60 or more, or 1.80 or less. A photosensitive composition containing a radical polymerizable monomer (2) having a high refractive index together with the radical polymerizable monomer (1) can form a hologram layer having a large refractive index modulation amount (Δn).

As the radical polymerizable monomer (2) having the above refractive index, for example, a radical polymerizable monomer having an aromatic ring is preferable, an aromatic ring-containing monofunctional (meth)acrylate, an aromatic ring-containing polyfunctional (meth)acrylate, and an aromatic ring-containing vinyl monomer are more preferable, an aromatic ring-containing monofunctional (meth)acrylate and an aromatic ring-containing polyfunctional (meth)acrylate are even more preferable, and a benzene ring-containing monofunctional (meth)acrylate, a naphthalene ring-containing monofunctional (meth)acrylate, a benzotriazole ring-containing monofunctional (meth)acrylate, a dinaphthothiophene ring-containing monofunctional (meth)acrylate, a benzene ring-containing polyfunctional (meth)acrylate, a naphthalene ring-containing polyfunctional (meth)acrylate, a phenanthrene ring-containing polyfunctional (meth)acrylate, a dinaphthothiophene ring-containing polyfunctional (meth)acrylate, and a fluorene ring-containing polyfunctional (meth)acrylate, as well as halides of these monomers, are even more preferable.

As the radical polymerizable monomer (2), phenoxybenzyl (meth)acrylate, 2-(o-phenylphenoxy)polyethylene glycol (meth)acrylate, 1-naphthylmethyl (meth)acrylate, 2-[2'-hydroxy-5'-((meth)acryloyloxyethyl)phenyl]-2H-benzotriazole, 6-(meth)acryloyloxymethyldinaphthothiophene, 4,4'-bis(2-(meth)acryloxyethoxy)biphenyl, naphthalenedithiol di(meth)acrylate, and 9,9-bis(4-(2-(meth)acryloyloxyethoxy)phenyl)fluorene are preferred, and from the viewpoints of refractive index modulation amount (Δn) and diffraction efficiency, 2-[2'-hydroxy-5'-((meth)acryloyloxyethyl)phenyl]-2H-benzotriazole is more preferred.

The photosensitive composition can contain one or more radically polymerizable monomers (2).

The refractive index of the radical polymerizable monomers (1) and (2) is preferably larger than that of the cationic polymerizable monomer, more preferably 0.05 or more, even more preferably 0.10 or more, and even more preferably 0.15 or more. In this manner, for example, a desired amount of refractive index modulation can be obtained.
The refractive index of the radical polymerizable monomers (1) and (2) is preferably larger than the refractive index of the binder resin, more preferably 0.05 or more, even more preferably 0.10 or more, and even more preferably 0.15 or more. In this manner, for example, a desired amount of refractive index modulation can be obtained.

<Cationically polymerizable monomer>
The photosensitive composition may further contain a cationic polymerizable monomer. By using a radical polymerizable monomer and a cationic polymerizable monomer in combination, for example, the crosslink density (density) and durability of the formed hologram layer can be improved.

A cationic polymerizable monomer is a compound that undergoes cationic polymerization due to the Bronsted acid or Lewis acid generated by decomposition of a photocationic polymerization initiator upon irradiation with light. Examples of cationic polymerizable monomers include compounds having cationic polymerizable functional groups. Examples of cationic polymerizable functional groups include epoxy groups and oxetanyl groups.

As the cationic polymerizable monomer, a monomer having an epoxy group is preferable. Examples of the monomer having an epoxy group include a monofunctional epoxy compound having one epoxy group and a polyfunctional epoxy compound having two or more epoxy groups. The number of epoxy groups in the polyfunctional epoxy compound may be 10 or less, 8 or less, or 6 or less.

Examples of monofunctional epoxy compounds include phenyl glycidyl ether, dibromophenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, vinyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, 1,3-butadiene monoxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, and cyclohexene oxide.

Examples of polyfunctional epoxy compounds include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,9-nonanediol diglycidyl ether, 1,6-dimethylol perfluorohexane diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerin polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and resorcinol diglycidyl ether. , bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, brominated bisphenol S diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, epoxy novolac resin, adipic acid diglycidyl ester, orthophthalic acid diglycidyl ester, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, 2-(3,4-epoxycyclohexyl)-3',4'-epoxy-1,3-dioxane-5-s Pyrocyclohexane, bis(3,4-epoxycyclohexylmethyl)adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate, 4',5'-epoxy-2'-methylcyclohexylmethyl-4,5-epoxy-2-methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, di(3,4-epoxycyclohexylmethyl)ether of ethylene glycol, ethylene glycol-bis(3,4-epoxycyclohexanecarboxylate), 1,4-bis(2,3-epoxypropoxypa -fluoroisopropyl)cyclohexane, 4,4'-bis(2,3-epoxypropoxyperfluoroisopropyl)diphenyl ether, bis(2,3-epoxycyclopentyl)ether, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1,2,7,8-diepoxyoctane, 1,2,5,6-diepoxycyclooctane, and 1,2,5,6-diepoxy-4,7-methanoperhydroindene, 1,4-bis(2',3'-epoxypropyl)perfluoro-n-butane, 1,6-bis(2',3'-epoxypropyl)perfluoro-n-hexane, 1,3-bis[(3,4-epoxycyclohexyl-2-ethyl)-1,1,3,3-tetramethyldisiloxane.

Examples of monomers having an oxetanyl group include monofunctional oxetane compounds having one oxetanyl group, and polyfunctional oxetane compounds having two or more oxetanyl groups. The number of oxetanyl groups in a polyfunctional oxetane compound may be 10 or less, 8 or less, or 6 or less.

Examples of monofunctional oxetane compounds include 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(phenoxymethyl)oxetane, 3,3-diethyloxetane, and 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane. Examples of polyfunctional oxetane compounds include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, di(1-ethyl(3-oxetanyl))methyl ether, and pentaerythritol tetrakis(3-ethyl-3-oxetanylmethyl)ether.

Cationic polymerizable monomers also include vinyl ethers. Examples of vinyl ethers include vinyl 2-chloroethyl ether, vinyl n-butyl ether, triethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, trimethylolethane trivinyl ether, and vinyl glycidyl ether.

The refractive index of the cationic polymerizable monomer may be less than 1.50, less than 1.47, or may be, for example, 1.35 or more. A photosensitive composition containing a cationic polymerizable monomer with a low refractive index and a radically polymerizable monomer with a high refractive index can form, for example, a hologram layer with a large refractive index modulation amount (Δn).

The cationic polymerizable monomer may be liquid at room temperature. By using such a cationic polymerizable monomer, for example, a radical polymerizable monomer can be polymerized in a photosensitive material layer having a relatively low viscosity.

The photosensitive composition can contain one or more cationic polymerizable monomers.

The photosensitive composition preferably contains at least a monomer having an epoxy group as a cationic polymerizable monomer. A photosensitive composition containing a monomer having an epoxy group together with the radically polymerizable monomers (1) and (2) can form, for example, a hologram layer with a high crosslink density (density), and therefore can suppress the migration of low molecular weight components to the hologram layer.

<Binder resin>
The photosensitive composition contains a binder resin, which, for example, improves the film-forming properties of the photosensitive composition, as well as the film thickness uniformity, refractive index modulation amount, heat resistance, and mechanical properties of the photosensitive material layer and the hologram layer, and stabilizes the hologram formed by holographic exposure.

Examples of binder resins include binder resins having cationic polymerizable groups, thermosetting resins other than binder resins having cationic polymerizable groups, and thermoplastic resins. Among these, binder resins having cationic polymerizable groups are preferred.

The binder resin having a cationic polymerizable group has, for example, a cationic polymerizable group in a side chain. The binder resin is a polymer having a cationic polymerizable group, and is preferably a (meth)acrylic resin having a cationic polymerizable group (hereinafter also referred to as a "cationically polymerizable group-containing (meth)acrylic resin").

The binder resin having a cationic polymerizable group, for example, improves the film-forming property of the photosensitive composition, as well as the film thickness uniformity, refractive index modulation amount, heat resistance, and mechanical properties of the photosensitive material layer and the hologram layer, and stabilizes the hologram formed by holographic exposure. When a binder resin having a cationic polymerizable group is used as the binder resin, the strength of the hologram layer is increased by curing the resin by heat treatment, and the hologram recording characteristics are improved, and a stable layer structure can be formed. A part of the cationic polymerizable group of the resin interacts with a part of the functional group of the photopolymerizable monomer by light irradiation, and a chemical bond can be formed. In this case, the photopolymerizable monomer is fixed by light irradiation after hologram recording, and the strength of the hologram layer can be improved.

Examples of cationic polymerizable groups include epoxy groups, oxetanyl groups (oxetane rings), vinyl ether groups, vinylamino groups, and vinylamide groups. Among these, epoxy groups and oxetanyl groups are preferred, and epoxy groups are more preferred.

The polymer having a cationic polymerizable group can be obtained, for example, by copolymerizing a vinyl compound having a cationic polymerizable group (hereinafter referred to as a "vinyl monomer containing a cationic polymerizable group") with a polymerizable monomer other than the vinyl monomer. The polymer having a cationic polymerizable group is preferably a (meth)acrylic copolymer having a cationic polymerizable group in a side chain, and can be obtained, for example, by copolymerizing at least a vinyl monomer containing a cationic polymerizable group with a (meth)acrylate compound.
Each of the monomers explained below can be used alone or in combination.

Examples of vinyl monomers containing a cationic polymerizable group include vinyl monomers having an epoxy group and vinyl monomers having an oxetanyl group (oxetane ring).

Examples of vinyl monomers having an epoxy group include epoxy group-containing (meth)acrylates. Examples of epoxy group-containing (meth)acrylates include glycidyl group-containing (meth)acrylates such as glycidyl (meth)acrylate and glycidyloxyalkyl (meth)acrylate; alicyclic epoxide group-containing (meth)acrylates such as 3,4-epoxycyclohexyl (meth)acrylate. Examples of glycidyloxyalkyl (meth)acrylates include glycidyloxyC _2-6 alkyl (meth)acrylates such as glycidyloxyethyl (meth)acrylate, glycidyloxypropyl (meth)acrylate, and glycidyloxybutyl (meth)acrylate.

Vinyl monomers having an epoxy group also include allyl glycidyl ether; vinyl monomers having a cycloalkene oxide group, such as 4-vinyl-1-cyclohexene oxide and 4-vinyl-1-cyclohexene dioxide.

Examples of vinyl monomers having an oxetane ring include oxetane ring-containing (meth)acrylates such as 3-ethyl-3-oxetanylmethyl (meth)acrylate; and oxetane ring-containing vinyl ethers such as 3-ethyl-3-(4-vinyloxycyclohexyloxymethyl)oxetane.

Among the vinyl monomers containing a cationic polymerizable group, vinyl monomers containing an epoxy group are preferred, epoxy group-containing (meth)acrylates are more preferred, and glycidyl group-containing (meth)acrylates are even more preferred.

In the polymer having a cationically polymerizable group, the content of the structural unit derived from the vinyl monomer containing a cationically polymerizable group may be 8% by mass or more, 10% by mass or more, and 65% by mass or less, 60% by mass or less, or 55% by mass or less. The content of each structural unit is measured by ^1H -NMR.

As the polymerizable monomer copolymerizable with the cationic polymerizable group-containing vinyl monomer (hereinafter also referred to as "copolymerizable monomer"), one or more of the radical polymerizable monomers described above can be used, and examples thereof include the above-mentioned monofunctional (meth)acrylates, the above-mentioned styrene-based monomers, and the above-mentioned vinyl monomers. Specific examples include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and lauryl (meth)acrylate; hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate; and styrene-based monomers such as styrene, 2-bromostyrene, and α-methylstyrene.

In the polymer having a cationic polymerizable group, the content of the structural unit derived from the above copolymerization monomer may be 92% by mass or less, 90% by mass or less, 35% by mass or more, 40% by mass or more, or 45% by mass or more.

From the viewpoint of the diffusion and migration ability of the photopolymerizable monomer during hologram recording and high-temperature storage stability, the weight-average molecular weight of the polymer having a cationic polymerizable group may be 10,000 or more, 30,000 or more, 50,000 or more, or 300,000 or less, 250,000 or less, or 200,000 or less. In this disclosure, the weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

The photosensitive composition can contain one or more binder resins having cationic polymerizable groups.

Examples of thermosetting resins include unsaturated polyester, epoxy-modified unsaturated polyester, (meth)acrylic urethane resin, epoxy-modified (meth)acrylic resin, alkyd resin, and phenol resin. When a thermosetting resin is used as a binder resin, the strength of the hologram layer can be increased by hardening the thermosetting resin through heat treatment, improving the hologram recording characteristics, and forming a stable layer structure. When irradiated with light, some of the functional groups of the thermosetting resin interact with some of the functional groups of the photopolymerizable monomer, forming a chemical bond. In this case, the photopolymerizable monomer is fixed by irradiation with light after hologram recording, improving the strength of the hologram layer.

The weight average molecular weight of the thermosetting resin may be 5,000 or more, or 10,000 or more, or may be 100,000 or less, or may be 50,000 or less, which can further improve the strength of the hologram layer, for example.
The photosensitive composition can contain one or more thermosetting resins.

Examples of thermoplastic resins include (meth)acrylic resins, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl formal, polyvinyl carbazole, polyvinyl acetate, ethylene-vinyl acetate copolymers, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, poly-1,2-dichloroethylene, polyvinylidene fluoride, polytetrafluoroethylene, polystyrene, poly-α-methylstyrene, poly-o-methylstyrene, poly-p-methylstyrene, poly-p-phenylstyrene, poly-2,5-dichlorostyrene, poly-p-chlorostyrene, and poly -α-vinyl naphthalate, styrene-(meth)acrylonitrile copolymer, styrene-divinylbenzene copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, hydrogenated styrene-butadiene-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polyvinylpyrrolidone, polyethylene terephthalate, polyethylene naphthalate, polyurethane, polycarbonate, ethyl cellulose, cellulose acetate, cellulose triacetate, cellulose acetate butyrate, polyarylate, polysulfone and polyethersulfone.

Of these, (meth)acrylic resins are preferred. Examples of the (meth)acrylic resin include poly(meth)acrylic acid, polymethyl(meth)acrylate, polyethyl(meth)acrylate, polypropyl(meth)acrylate, poly-n-butyl(meth)acrylate, polyisobutyl(meth)acrylate, polytert-butyl(meth)acrylate, polyhexyl(meth)acrylate, polycyclohexyl(meth)acrylate, poly2-ethylhexyl(meth)acrylate, polyphenyl(meth)acrylate, polybenzyl(meth)acrylate, poly1-phenylethyl(meth)acrylate, poly2-phenylethyl(meth)acrylate, polyfurfuryl(meth)acrylate, polydiphenylmethyl(meth)acrylate, polypentachlorophenyl(meth)acrylate, polynaphthyl(meth)acrylate, poly2-hydroxyethyl(meth)acrylate and poly(meth)acrylonitrile, as well as copolymers of two or more of the monomers constituting these polymers.
The photosensitive composition can contain one or more thermoplastic resins.

The weight average molecular weight of the thermoplastic resin may be 10,000 or more, 30,000 or more, or 50,000 or more, or 300,000 or less, 250,000 or less, or 200,000 or less, from the viewpoint of the diffusion and migration ability of the photopolymerizable monomer during hologram recording and high-temperature storage stability. In this disclosure, the weight average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

The refractive index of the binder resin may be less than 1.50, less than 1.45, or may be, for example, 1.35 or more. A photosensitive composition containing a binder resin with a low refractive index and a radically polymerizable monomer with a high refractive index can form, for example, a hologram layer with a large refractive index modulation amount (Δn).

<Photopolymerization initiator>
The photosensitive composition contains a photopolymerization initiator. Examples of the photopolymerization initiator include a photoradical polymerization initiator and a photocationic polymerization initiator.

A photoradical polymerization initiator is a compound that generates active radicals upon irradiation with light.
Examples of the photoradical polymerization initiator include azo compounds, azide compounds, diazo compounds, o-quinone diazide compounds, acylphosphine oxide compounds, thioxanthone compounds, phenyl ketone compounds, benzoin compounds, anthraquinone compounds, imidazole compounds, bisimidazole compounds, titanocene compounds, organic thiol compounds, halogenated hydrocarbon compounds, triazine compounds, and organic peroxides; and onium salts such as aromatic iodonium salts and aromatic sulfonium salts.

The photosensitive composition can contain one or more photoradical polymerization initiators.

As the photocationic polymerization initiator, a photoacid generator is preferred. The photoacid generator is a compound that generates a Bronsted acid or a Lewis acid by irradiation with light. Examples of the photoacid generator include onium salts and iron arene complexes. Examples of the onium salt include aromatic iodonium salts such as diaryliodonium salts, aromatic sulfonium salts such as triarylsulfonium salts, aromatic diazonium salts, and aromatic phosphonium salts. Examples of the iron arene complex include biscyclopentadienyl-(η ⁶ -isopropylbenzene)-iron(II) hexafluorophosphate.

Examples of aromatic iodonium salts and aromatic sulfonium salts include chlorides, bromides, tetrafluoroborates, hexafluorophosphates, hexafluoroantimonates, trifluoromethanesulfonates, and 9,10-dimethoxyanthracene-2-sulfonates of aromatic iodonium or aromatic sulfonium.

Specific examples of aromatic iodonium salts include diphenyliodonium, 4,4'-dichlorodiphenyliodonium, 4,4'-dimethoxydiphenyliodonium, (4-methoxyphenyl)phenyliodonium, 4,4'-ditert-butyldiphenyliodonium, (4-tert-butylphenyl)phenyliodonium, 3,3'-dinitrodiphenyliodonium, (3-nitrophenyl)phenyliodonium, and 4,4'-di-n-alkyl(C10-13)diphenyliodonium. Examples of such compounds include chlorides, bromides, tetrafluoroborate, tetrakispentafluorophenylborate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, trifluoromethanesulfonate, nonafluorobutane-1-sulfonate, heptadecafluorooctane sulfonate, tridecafluorohexane-1-sulfonate, 9,10-dimethoxyanthracene-2-sulfonate, p-toluenesulfonate, and camphorsulfonate.

Specific examples of aromatic sulfonium salts include chlorides, bromides, tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, trifluoromethanesulfonate, nonafluorobutane-1-sulfonate, heptadecafluorooctane sulfonate, tridecafluorohexane-1-sulfonate, 9,10-dimethoxyanthracene-2-sulfonate, p-toluenesulfonate, and camphorsulfonate, such as triphenylsulfonium, (4-hydroxyphenyl)diphenylsulfonium, (4-methoxyphenyl)diphenylsulfonium, (4-tert-butylphenyl)diphenylsulfonium, and [4-(phenylthio)phenyl]diphenylsulfonium.

The photosensitive composition can contain one or more cationic photopolymerization initiators.

The photosensitive composition may contain a photoradical polymerization initiator and a photocationic polymerization initiator. Such a photosensitive composition can effectively promote polymerization of radically polymerizable monomers and cationic polymerizable monomers by irradiation with light.

The photosensitive composition may contain a photopolymerization initiator that functions as both a photoradical polymerization initiator and a photocationic polymerization initiator. In this case, the photosensitive composition may contain only one such photopolymerization initiator. Examples of such photopolymerization initiators include aromatic iodonium salts and aromatic sulfonium salts.

From the viewpoint of stabilizing the recorded hologram, it is preferable that the photopolymerization initiator is one that is decomposed after the hologram is recorded.

<Sensitizing dye>
The photosensitive composition contains a sensitizing dye that sensitizes the photopolymerization initiator. The sensitizing dye is generally a component that absorbs light and has the function of increasing the sensitivity of the photopolymerization initiator to the recording light. By containing the sensitizing dye, the photosensitive material layer becomes active to visible light, and a hologram can be recorded using visible light.

Examples of sensitizing dyes include thiopyrylium salt dyes, merocyanine dyes, quinoline dyes, styrylquinoline dyes, coumarin dyes, ketocoumarin dyes, thioxanthene dyes, xanthene dyes, oxonol dyes, cyanine dyes, rhodamine dyes, squarylium dyes, pyrylium ion dyes, cyclopentanone dyes, cyclohexanone dyes, and diphenyliodonium ion dyes.

When the hologram layer is required to be colorless and transparent (for example, when used as a head-up display for an automobile or the like), cyanine dyes, coumarin dyes, and squarylium dyes are preferred as sensitizing dyes. Cyanine dyes and squarylium dyes are generally easily decomposed by light, so by post-exposure or leaving the hologram layer under indoor light or sunlight for several hours to several days, the dyes in the hologram layer are decomposed and no longer absorb in the visible range, resulting in a colorless and transparent hologram layer.

Examples of cyanine dyes include anhydro-3,3'-dicarboxymethyl-9-ethyl-2,2'-thiacarbocyanine betaine, anhydro-3-carboxymethyl-3',9-diethyl-2,2'-thiacarbocyanine betaine, 3-ethyl-9-methyl-3'-(3-sulfatobutyl)thiacarbocyanine betaine, 3,3'-diethyl-2,2'-thiacarbocyanine iodine salt, 3,3'-diethyl-2,2'-thiacarbocyanine bromine salt, 3,3',9-triethyl-2,2'-thiacarbocyanine iodine salt, 3,9-diethyl-3 '-Carboxymethyl-2,2'-thiacarbocyanine iodine salt, 3,3',9-triethyl-2,2'-(4,5,4',5'-dibenzo)thiacarbocyanine iodine salt, 3,3',9-triethyl-2,2'-(4,5,4',5'-dibenzo)thiacarbocyanine bromine salt, 3,3',9-trimethyl-2,2'-(4,5,4',5'-dibenzo)thiacarbocyanine iodine salt, 3,3'-diethyl-2,2'-(6,7-,6',7'-dibenzo)thiacarbocyanine iodine salt, 3,3'-diethyl-9-methyl-2,2'-selenacarbocyanine anine iodide, 2-[3-(3-ethyl-2-benzothiazolidene)-1-propenyl]-6-[2-(3-ethyl-2-benzothiazolidene)ethylideneimino]-3-ethyl-1,3,5-thiadiazolium iodide, 2-[[3-allyl-4-oxo-5-(3-propyl-5,6-dimethyl-2-benzothiazolylidene)-ethylidene-2-thiazolinylidene]methyl]3-ethyl-4,5-diphenylthiazolinium iodide, 1,1',3,3,3',3'-hexamethyl-2,2'-indotricarbocyanine iodide, 3,3' -Diethyl-2,2'-thiatricarbocyanine perchlorate, anhydro-1-ethyl-4-methoxy-3'-carboxymethyl-5'-chloro-2,2'-quinothiacyanine betaine, anhydro-5,5'-diphenyl-9-ethyl-3,3'-disulfopropyloxacarbocyanine hydroxide triethylamine salt, and 2-[3-(3-ethyl-2-benzothiazolidene)-1-propenyl]-6-[2-(3-ethyl-2-benzothiazolidene)ethylideneimino]-3-ethyl-1,3,5-thiadiazolium iodine salt.

Examples of squarylium dyes include cyclobutenediylium, 1,3-bis[(3-ethyl-2(3H)-benzothiazolylidene)methyl]-2,4-dihydroxy-, dihydroxide, bis(inner salt), and cyclobutenediylium, 1,3-bis[(1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)methyl]-2,4-dihydroxy-, dihydroxide, bis(inner salt). , cyclobutenediylium, 1,3-bis[(1-ethyl-1,3-dihydro-3,3-dimethyl-2H-indol-2-ylidene)methyl]-2,4-dihydroxy-, dihydroxide, bis(inner salt), cyclobutenediylium, 1,3-bis[(5-chloro-1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)methyl]-2,4-dihydroxy-, dihydroxide, bis(molecular salt) Bis(inner salt), cyclobutenediylium, 1,3-bis[(1,3-dihydro-5-methoxy-1,3,3-trimethyl-2H-indol-2-ylidene)methyl]-2,4-dihydroxy-, dihydroxide, bis(inner salt), cyclobutenediylium, 1,3-bis[(1,3-dihydro-1,3,3-trimethyl-2H-benz[e]indol-2-ylidene)methyl]-2,4-dihydroxy-, dihydroxide Side, bis (inner salt), cyclobutenediylium, 1,3-dihydroxy-2,4-bis (2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)-, bis (inner salt), and cyclobutenediylium, 1,3-dihydroxy-2,4-bis (2,3,6,7-tetrahydro-8-hydroxy-1H,5H-benzo[ij]quinolizin-9-yl)-, bis (inner salt).

Examples of coumarin dyes include 3-(2-benzimidazolyl)-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(diethylamino)coumarin, 3-(2-benzimidazolyl)-7-(dimethylamino)coumarin, 3-(2-benzothiazolyl)-7-(dimethylamino)coumarin, 7-(diethylamino)-3-(1-methyl-2-benzimidazolyl)coumarin, 7-(dimethylamino)-3-(1-methyl-2-benzimidazolyl)coumarin, 7-(diethylamino)-3-( 1-ethyl-2-benzimidazolyl) coumarin, 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one, 10-(2-benzoxazolyl)-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one, 3,3'-carbonylbis(7-diethylaminocoumarin), and 3,3'-carbonylbis(7-dimethylaminocoumarin).

The photosensitive composition can contain one or more sensitizing dyes.

<Additives>
The photosensitive composition may contain additives, if necessary.
Examples of additives include fine particles, thermal polymerization inhibitors, chain transfer agents, silane coupling agents, leveling agents and colorants.Examples of fine particles include organic fine particles having low-density polyethylene, high-density polyethylene, polypropylene or poly(meth)acryl as resin skeleton, fluorine-based fine particles in which part or all of the hydrogen atoms in the resin skeleton constituting the organic fine particles are replaced with fluorine atoms; inorganic particles such as silica, mica, talc and titania.
The photosensitive composition may contain one or more additives.

<Organic solvent>
From the viewpoint of improving coating suitability, the photosensitive composition preferably contains an organic solvent. When the photosensitive composition contains a component that is liquid at room temperature, an organic solvent may not be necessary. Examples of organic solvents include ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, acetone, and cyclohexanone; ester solvents such as ethyl acetate, butyl acetate, and ethylene glycol diacetate; aromatic hydrocarbon solvents such as toluene and xylene; cellosolve solvents such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; alcohol solvents such as methanol, ethanol, propanol, and butanol; ether solvents such as tetrahydrofuran and dioxane; and halogenated hydrocarbon solvents such as dichloromethane and chloroform. The organic solvent may be one type or a mixed solvent of two or more types.

<Content of each ingredient>
The content of the radical polymerizable monomer in the photosensitive composition may be 5 parts by mass or more, 10 parts by mass or more, 20 parts by mass or more, and 90 parts by mass or less, 50 parts by mass or less, or 40 parts by mass or less, based on 100 parts by mass of the total solid content of the photosensitive composition. The content of the radical polymerizable monomer is the sum of the content of the radical polymerizable monomer (1) and the content of the radical polymerizable monomer (2). The solid content refers to all components other than the solvent, and the solid content also includes monomers that are liquid at room temperature.

The content of the radical polymerizable monomer (1) in the photosensitive composition may be 30% by mass or more, 40% by mass or more, 50% by mass or more, or 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, or 65% by mass or less, based on the total amount of the radical polymerizable monomer. A hologram layer formed from a photosensitive composition having a content of the radical polymerizable monomer (1) equal to or greater than the lower limit has, for example, a superior refractive index modulation amount (Δn) and diffraction efficiency, and is also superior in transparency. A photosensitive composition having a content of the radical polymerizable monomer (1) equal to or less than the upper limit can, for example, form a hologram layer that diffracts image light to display an image, and can form a hologram layer that is superior in refractive index modulation amount (Δn) and diffraction efficiency.

The content of the cationic polymerizable monomer in the photosensitive composition may be 5 parts by mass or more, 10 parts by mass or more, 20 parts by mass or more, or 90 parts by mass or less, 50 parts by mass or less, or 40 parts by mass or less, based on 100 parts by mass of the total solid content of the photosensitive composition. In this manner, for example, a desired amount of refractive index modulation can be obtained, and further, a hologram layer having excellent durability can be obtained.

The content of the binder resin in the photosensitive composition may be 5 parts by mass or more, 10 parts by mass or more, or 90 parts by mass or less, or 50 parts by mass or less, per 100 parts by mass of the total solid content of the photosensitive composition. In this manner, for example, the strength of the hologram layer can be further improved.

The content of the photopolymerization initiator in the photosensitive composition may be 0.1 parts by mass or more, 1 part by mass or more, or 10 parts by mass or less, or 5 parts by mass or less, per 100 parts by mass of the total solid content of the photosensitive composition. In this embodiment, for example, the photopolymerizable monomer (for example, the above-mentioned radical polymerizable monomer) is sufficiently polymerized by light irradiation, and the desired amount of refractive index modulation is obtained.

The content of the sensitizing dye in the photosensitive composition may be 0.001 parts by mass or more, 0.01 parts by mass or more, 0.05 parts by mass or more, 0.1 parts by mass or more, or 2 parts by mass or less, 1.5 parts by mass or less, 1.2 parts by mass or less, or 0.3 parts by mass or less, based on 100 parts by mass of the total solid content of the photosensitive composition. In this manner, for example, the sensitivity of the photopolymerization initiator can be improved and the transparency of the hologram layer can be ensured.

In one embodiment, the photosensitive composition contains a radical polymerizable monomer (1), a (meth)acrylate compound as the radical polymerizable monomer (2), a monomer having an epoxy group as the cationic polymerizable monomer, and a cationic polymerizable group-containing (meth)acrylic resin as the binder resin. Such a photosensitive composition can form a hologram layer that has a high crosslink density and excellent refractive index modulation properties, for example.

[Hologram recording sheet and hologram sheet]
The hologram recording sheet of the present disclosure includes a substrate and a photosensitive material layer.
The hologram sheet of the present disclosure includes a substrate and a hologram layer.

The photosensitive material layer has a first surface facing the substrate and a second surface opposite the first surface. In this specification, the photosensitive material layer refers to a layer containing a radically polymerizable monomer before holographic exposure (interference exposure). The hologram layer has a first surface facing the substrate and a second surface opposite the first surface. The substrate has a first surface facing the photosensitive material layer or the hologram layer and a second surface opposite the first surface.

The hologram recording sheet may further include a first protective layer on the second surface of the photosensitive material layer. The hologram recording sheet may further include a second protective layer on the second surface of the substrate.

The hologram sheet may further include a first protective layer on the second surface of the hologram layer. The hologram sheet may further include a second protective layer on the second surface of the substrate.

Embodiments of the present disclosure will be described below with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios have been appropriately altered and exaggerated from their actual equivalents for the convenience of illustration and ease of understanding. Furthermore, configurations shown in some drawings may be omitted in other drawings.

In this specification, terms that specify shapes and geometric conditions and their degrees, such as "parallel," "orthogonal," and "same," as well as values of lengths and angles, are not limited to their strict meanings, but are interpreted to include the range in which similar functions can be expected.

The structure of a hologram recording sheet will be described with reference to FIGS.
The hologram recording sheet 1 shown in Fig. 1 includes a substrate 10 and a photosensitive material layer 20 in this order. The substrate 10 has a first surface 10a facing the photosensitive material layer 20 and a second surface 10b facing the first surface 10a. The photosensitive material layer 20 has a first surface 20a facing the substrate 10 and a second surface 20b facing the first surface 20a. The hologram recording sheet 1 shown in Fig. 2 includes a substrate 10, a photosensitive material layer 20, and a first protective layer 30 in this order. The hologram recording sheet 1 shown in Fig. 3 includes a second protective layer 40, the substrate 10, the photosensitive material layer 20, and a first protective layer 30 in this order.

The structure of the hologram sheet will be described with reference to FIGS.
The hologram sheet 2 shown in Fig. 4 includes, in this order, a substrate 10 and a hologram layer 22. The hologram layer 22 has a first surface 22a facing the substrate 10 and a second surface 22b opposing the first surface 22a. The hologram sheet 2 shown in Fig. 5 includes, in this order, a substrate 10, a hologram layer 22, and a first protective layer 30.

The hologram sheet of the present disclosure can be used for applications such as head-up displays, general three-dimensional displays, lenses, diffraction gratings, interference filters, optical fiber couplers, optical polarizers for facsimiles, security cards, memory materials for credit cards and ID cards, architectural window glass, and advertising media. Among these, the hologram sheet of the present disclosure is particularly suitable for head-up display applications.

In one embodiment, the total light transmittance of the hologram sheet of the present disclosure measured in accordance with JIS K7136:2000 may be 70% or more, 75% or more, or 80% or more. The higher the total light transmittance, the more preferable it is, but the upper limit may be, for example, 99%, 95%, or 90%. The total light transmittance is measured using a haze meter (product name "HM-50", manufactured by Murakami Color Research Laboratory). The total light transmittance is measured three times for one hologram sheet, and the average value of the values obtained from the three measurements is taken as the total light transmittance of the hologram sheet.

In one embodiment, the haze of the hologram sheet of the present disclosure, measured in accordance with JIS K7136:2000, may be 10% or less, 5% or less, or 3% or less. The lower the haze, the better, but the lower limit may be, for example, 0.1% or 0.3%. The haze is measured using a haze meter (product name "HM-50", manufactured by Murakami Color Research Laboratory). The haze is measured three times for one hologram sheet, and the average value of the three measurements is taken as the haze of the hologram sheet.

<Substrate>
The hologram recording sheet and the hologram sheet of the present disclosure include a substrate, which supports, for example, the photosensitive material layer in the case of the hologram recording sheet, and the hologram layer in the case of the hologram sheet.

Examples of resins that may be used to form the substrate include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; cellulose-based resins such as diacetyl cellulose and triacetyl cellulose; (meth)acrylic resins such as polymethyl methacrylate; polyolefins such as polyethylene and polypropylene; cyclic polyolefins such as norbornene-based resins; vinyl resins such as polystyrene, polyvinyl alcohol, and polyethylene/vinyl alcohol; polycarbonate; polysulfone; and polyarylate.

The substrate is a transparent layer.
In this specification, "transparent" means that the visible light transmittance is 50% or more, and preferably 80% or more. The visible light transmittance is specified as the average value of the total light transmittance at each wavelength when measured at 1 nm intervals in the measurement wavelength range of 380 nm to 780 nm using a spectrophotometer (Shimadzu Corporation's "UV-3100PC", compliant with JIS K0115:2020).

The thickness of the substrate may be 10 μm or more, 30 μm or more, 50 μm or more, or 80 μm or more. The thickness of the substrate may be 500 μm or less, 400 μm or less, 300 μm or less, or 200 μm or less. Substrates having such a thickness have an excellent balance of transparency and strength, for example.

<Photosensitive Material Layer and Hologram Layer>
The photosensitive material layer and the hologram layer have, for example, a flat shape.
The photosensitive material layer and the hologram layer may have a rectangular shape in a plan view.

The photosensitive material layer is, for example, a layer for recording a hologram.
The hologram layer is transparent. The hologram layer is, for example, a volume hologram, such as a Lippmann volume hologram. The hologram layer may be a reflection hologram. However, without being limited thereto, the hologram layer may also be a transmission hologram.

In one embodiment, the holographic layer has a structure represented by the following formula (1A):

In formula (1A), R ¹ to R ⁸ , n1 and n2, k1 to k4, and p1 and p2 each have the same meaning as the same symbols in formula (1), and the explanation thereof will be omitted in this section.

The thickness of the photosensitive material layer and the hologram layer may each be 1 μm or more, 3 μm or more, 5 μm or more, or 100 μm or less, 50 μm or less, or 30 μm or less. From the viewpoint of transparent hologram characteristics, the thickness of the photosensitive material layer and the hologram layer may each be 3 μm or more, 5 μm or more, or 30 μm or less, or 20 μm or less. When the thickness of the photosensitive material layer is 1 μm or more, the formability of the hologram tends to be improved. When the thickness of the photosensitive material layer is 100 μm or less, the transmittance of the hologram layer tends to be improved.

In one embodiment, the hologram layer has a recording section in which interference fringes are recorded. The recording section may be provided on the entire surface of the hologram layer in a plan view. When the hologram sheet of the present disclosure is used for a head-up display, as shown in FIG. 6, the hologram layer diffracts the image light irradiated from the image forming device 103 with interference fringes and directs the image light toward the user 105. This allows the user 105 to view the image information contained in the image light as a virtual image together with the background at the observation position 106 behind the combiner 104.

The hologram layer may have multiple recording sections. The multiple recording sections can diffract light of different wavelengths with high efficiency. For example, image light from an image forming device may include blue light, green light, and red light. In this example, the hologram layer may include a recording section that diffracts blue light with high efficiency, a recording section that diffracts green light with high efficiency, and a recording section that diffracts red light with high efficiency. When the recording section is a volume hologram, a single recording section may diffract light in multiple wavelength ranges with high efficiency by multiplex recording.

The photosensitive material layer contains, for example, a radical polymerizable monomer (1), a radical polymerizable monomer (2) other than the radical polymerizable monomer (1), and optionally a cationic polymerizable monomer, a binder resin, a photopolymerization initiator, and a sensitizing dye. The photosensitive material layer can be formed, for example, using the photosensitive composition of the present disclosure. The hologram layer can be formed, for example, by subjecting such a photosensitive material layer to holographic exposure and then curing the layer.

In one embodiment, the refractive index modulation amount (Δn) of the hologram layer may be 0.025 or more, 0.030 or more, 0.040 or more, 0.045 or more, 0.050 or more, 0.055 or more, 0.060 or more, or 0.065 or more. The upper limit of Δn is not particularly limited, but may be, for example, 0.08. A volume hologram layer having such a Δn can express an image with high brightness. Details of the method for measuring Δn are described in the Examples section.

The gel fraction of the hologram layer may be 30% by mass or more, 35% by mass or more, 40% by mass or more, or 45% by mass or more. The upper limit of the gel fraction is not particularly limited, but is, for example, 95% by mass, 90% by mass, or 80% by mass. By using a radical polymerizable monomer, a cationic polymerizable monomer, and further a cationic polymerizable group-containing (meth)acrylic resin in combination, for example, a hologram layer having a high gel fraction as described above can be formed.

The gel fraction is expressed by the following formula.
Gel fraction = W2/W1 x 100 (%)
The initial mass of the hologram layer is W1. The hologram layer is immersed in methyl ethyl ketone (MEK) as a solvent at room temperature (23° C.) for 24 hours, and then the hologram layer is taken out, the solvent is wiped off, and the hologram layer is dried. The mass of the hologram layer after drying is W2.

The photosensitive material layer can be formed, for example, by applying a photosensitive composition to the surface of a substrate or the like and drying the composition. Examples of methods for applying the photosensitive composition include spraying, spin coating, wire bar coating, dip coating, air knife coating, die coating, comma coating, roll coating, blade coating, and doctor roll coating.

The photosensitive composition is dried, for example, using a hot plate, an oven, or a belt furnace. The drying temperature may be 50°C or higher, 60°C or higher, or 70°C or higher, and may be 150°C or lower, 140°C or lower, or 130°C or lower. The drying time may be 1 minute or longer, and may be 60 minutes or lower, 30 minutes or lower, 20 minutes or lower, or 10 minutes or lower.

The hologram layer is formed, for example, by recording a hologram in a photosensitive material layer. Specifically, holographic exposure is performed on the photosensitive material layer. This causes a polymerization reaction of the photopolymerizable monomer in the exposed or highly exposed parts of the photosensitive material layer, forming a polymer. As a result, the photopolymerizable monomer moves from the non-exposed or lightly exposed parts to the exposed or highly exposed parts. The polymerization and concentration change of the photopolymerizable monomer creates a refractive index difference in the photosensitive material layer, forming an interference pattern (interference fringes) in the photosensitive material layer, thereby recording a hologram. In this way, a hologram layer can be obtained.

The exposure dose during holographic exposure may be 10 mJ/ ^cm2 or more, or 50 mJ/ ^cm2 or more, or 500 mJ/ ^cm2 or less, or 200 mJ/ ^cm2 or less. The photosensitive material layer contains a sensitizing dye, so that it is active to visible light and a hologram can be recorded using visible light.

After recording the hologram in the photosensitive material layer, the hologram layer may be further subjected to a heat treatment and/or full-surface exposure in order to promote refractive index modulation and complete the polymerization reaction (fixation). When both the heat treatment and the full-surface exposure are performed, the order is not particularly limited, but it is preferable to perform the heat treatment first. In one embodiment, it is preferable to perform the heat treatment and then the full-surface exposure. This results in a hologram layer with superior crosslink density and durability.

The temperature during the heat treatment is, for example, 50°C to 150°C, and the treatment time is, for example, 5 minutes to 3 hours. The heat treatment promotes polymerization of monomers having epoxy groups, for example, and results in a hologram layer with a higher crosslink density.

In the full-surface exposure, the hologram layer is irradiated with, for example, ultraviolet light and/or visible light. Examples of light sources used in the full-surface exposure include ultra-high pressure mercury lamps, high pressure mercury lamps, carbon arc lamps, xenon arc lamps, metal halide lamps, fluorescent lamps of visible light, and LED lights. The amount of irradiation energy when performing full-surface exposure with ultraviolet light may be 500 mJ/cm ² or more, 1000 mJ/cm ² or more, and may be 5000 mJ/cm ² or less, or 3000 mJ/cm ² or less. The irradiation time when performing full-surface exposure with visible light may be 1 minute or more, 5 minutes or more, 10 minutes or more, and may be 2 hours or less, or 1 hour or less. By the full-surface exposure, for example, polymerization of the photopolymerizable monomer proceeds, and a hologram layer with a higher crosslink density is obtained. In addition, full-surface exposure may be performed for fading treatment of the sensitizing dye.

<First Protective Layer>
The hologram recording sheet of the present disclosure may further include a first protective layer on the second surface of the photosensitive material layer. The hologram sheet of the present disclosure may further include a first protective layer on the second surface of the hologram layer. The first protective layer can, for example, suppress foreign matter such as dust from adhering to the second surface of the photosensitive material layer or the hologram layer, suppress deterioration of the photosensitive material layer or the hologram layer due to abrasion, or in a combiner in which the hologram layer in the hologram sheet is in contact with a bonding material, suppress low molecular weight components such as plasticizers contained in the bonding material from penetrating into the interference fringes of the hologram layer.

Examples of resins constituting the first protective layer include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, cyclic polyolefins such as norbornene-based resins, (meth)acrylic resins such as polymethyl methacrylate, cellulose-based resins such as diacetyl cellulose and triacetyl cellulose, vinyl-based resins such as polyvinyl alcohol and polyethylene/vinyl alcohol, and fluororesins such as polycarbonate, polysulfone, and polytetrafluoroethylene.

The first protective layer on the photosensitive material layer may be, for example, a release film that can be peeled off from the photosensitive material layer. In a hologram recording sheet having such a release film, the release film can be peeled off from the photosensitive material layer when the sheet is used.

Examples of release films include resin films that may have been subjected to a release treatment, such as polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film, polyolefin films such as polyethylene film and polypropylene film, cyclic polyolefin films such as norbornene-based resin films, (meth)acrylic resin films such as polymethyl methacrylate film, and fluororesin films such as polytetrafluoroethylene film. Examples of release treatments include coating treatments with release agents such as fluorine-based release agents, silicone-based release agents, and long-chain alkyl-based release agents. Among these, polyester films, i.e., polyester-based release films, are preferred.

The first protective layer on the hologram layer may be, for example, a film that can adhere well to the hologram layer. Examples of the above film include resin films that may be subjected to an easy-adhesion treatment, such as polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film, polyolefin films such as polyethylene film and polypropylene film, cyclic polyolefin films such as norbornene-based resin films, and (meth)acrylic resin films such as polymethyl methacrylate film. Other examples include triacetyl cellulose film and polycarbonate film. Among these, polyester film and polycarbonate film are preferred.

The first protective layer overlaps the photosensitive material layer or the hologram layer in a planar view. For example, the outer periphery of the first protective layer may overlap the outer periphery of the photosensitive material layer or the hologram layer in a planar view.

The thickness of the first protective layer may be 5 μm or more, 10 μm or more, or 15 μm or more. The thickness of the first protective layer may be 200 μm or less, 150 μm or less, or 100 μm or less.

<Second Protective Layer>
The hologram recording sheet of the present disclosure may further include a second protective layer on the second surface of the substrate. The hologram sheet of the present disclosure may further include a second protective layer on the second surface of the substrate. The second protective layer can, for example, prevent foreign matter such as dust from adhering to the second surface of the substrate, or prevent the substrate from being deteriorated due to abrasion or the like.

Examples of resins constituting the second protective layer include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, cyclic polyolefins such as norbornene-based resins, (meth)acrylic resins such as polymethyl methacrylate, and fluororesins such as polytetrafluoroethylene.

The second protective layer may be, for example, a release film that can be peeled off from the substrate. In a hologram recording sheet and a hologram sheet that include such a release film, the release film can be peeled off from the substrate when they are used.

Examples of release films include resin films that may have been subjected to a release treatment, such as polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film, polyolefin films such as polyethylene film and polypropylene film, cyclic polyolefin films such as norbornene-based resin films, (meth)acrylic resin films such as polymethyl methacrylate film, and fluororesin films such as polytetrafluoroethylene film. Examples of release treatments include coating with a release agent such as a fluorine-based release agent, a silicone-based release agent, or a long-chain alkyl-based release agent.

The second protective layer overlaps the substrate in a plan view. For example, the outer periphery of the second protective layer may overlap the outer periphery of the substrate in a plan view.

The thickness of the second protective layer may be 5 μm or more, 10 μm or more, or 15 μm or more. The thickness of the second protective layer may be 200 μm or less, 150 μm or less, or 100 μm or less.

[Combiner, head-up display and moving object]
After describing the head-up display and the vehicle, the combiner will be described.
6 , the head-up display 102 has an image forming device 103 and a combiner 104. The head-up display 102 uses the combiner 104 to display an image formed by the image forming device 103 to a user 105. The combiner 104 is transparent. Therefore, the user 105 can observe the rear of the combiner 104 through the combiner 104. An imaging device may capture an image of the user 105 observing the combiner 104 through the combiner 104.

The head-up display 102 according to this embodiment can be applied to various fields. The head-up display 102 may be applied to a head-mounted display. The head-up display 102 may be applied to a teleprompter. The teleprompter may be used for lectures, imaging, etc.

In the example shown in FIG. 6, the head-up display 102 is applied to a moving body 101. The moving body 101 is a mobile device. The moving body 101 may be capable of moving with a human being on board. Examples of the moving body 101 include a ship, an airplane, a drone, a railroad car, and the automobile shown in the figure. As shown in FIG. 6, the combiner 104 may be applied to the front window of the automobile.

The image forming device 103 emits image light that forms an image. The user 105 observes the image by receiving the image light. The image light includes image information such as speed information, visibility assistance information, and navigation information. As shown in FIG. 6, the image forming device 103 may be disposed in a dashboard and hidden by the dashboard. The image forming device 103 is not particularly limited, and various devices capable of forming an image can be used. Examples of the image forming device 103 include a liquid crystal display device, a laser display device, and an EL display device. The image forming device 103 may have an optical sheet and a light source that illuminates the optical sheet from the back. The image light from the image forming device 103 is irradiated to the combiner 104. A projection optical system (not shown) may be provided between the image forming device 103 and the combiner 104. The projection optical system guides the image light from the image forming device 103 to the combiner 104. The projection optical system may include a mirror, a lens, a prism, a diffractive optical element, and a combination thereof.

The combiner 104 directs the image light from the image forming device 103 toward the user 105.

The combiner of the present disclosure comprises:
A pair of substrates;
a bonding material disposed between the pair of substrates so as to bond the pair of substrates to each other;
A hologram sheet according to the present disclosure positioned between a pair of substrates;
has.

The configuration of the combiner will be described with reference to FIG. 7. The combiner 104 has a pair of substrates 60, 62, a bonding material 70 disposed between the substrates 60, 62 so as to bond the pair of substrates 60, 62 to each other, and a hologram sheet 2 of the present disclosure positioned between the pair of substrates 60, 62. The hologram sheet 2 is disposed, for example, in the center of the pair of substrates 60, 62 in a plan view. The hologram sheet 2 is covered with the bonding material 70.

In the embodiment of FIG. 7, the combiner 104 has a layered structure including a substrate 62, a bonding material 70, a hologram sheet 2, a bonding material 70, and the substrate 60 in a part of a plan view.
The combiner 104 may have a laminated structure in a part of a plan view, the laminated structure including a substrate 62, a hologram sheet 2, a bonding material 70, and a substrate 60, with the substrate 62 and the hologram sheet 2 being in contact with each other.
The combiner 104 may have a laminated structure in a part of a planar view that includes a substrate 62, an adhesive layer (not shown), a hologram sheet 2, a bonding material 70, and a substrate 60, in which the substrate 62 and the adhesive layer are in contact and the adhesive layer and the hologram sheet 2 are in contact.

The combiner (or hologram sheet) of the present disclosure may have a first peak in the range of 495 nm or more and less than 570 nm in a transmission spectrum measured in a 25°C environment. The transmission spectrum is measured in the wavelength range of 400 nm or more and 780 nm or less at the center of the hologram layer. The first peak corresponds to, for example, a diffraction peak for green light.

In one embodiment, the hologram layer may have diffraction efficiency peaks for multiple wavelengths of light, and therefore the transmission spectrum may have multiple peaks. The combiner (or hologram sheet) of the present disclosure may further have a second peak in the range of 400 nm or more and less than 495 nm, and/or a third peak in the range of 570 nm or more and 700 nm or less, in the transmission spectrum measured in a 25°C environment. The second peak corresponds to, for example, a diffraction peak for blue light. The third peak corresponds to, for example, a diffraction peak for red light.

The hologram sheet of the present disclosure is suitable for use in combiners or laminated glass.

<Substrate>
The pair of substrates are arranged parallel to each other. The substrates are transparent plates. The substrates support a hologram sheet. In the example shown in FIG. 6, the pair of substrates 60, 62 function as windshield members constituting the front window of the moving body 101. In one embodiment, the substrate 60 is located on the opposite side to the user 105, that is, on the outside of the moving body 101. In one embodiment, the substrate 62 is located on the side of the user 105, that is, on the inside of the moving body 101. The material of the substrate may be inorganic glass such as soda lime glass or blue plate glass. That is, the substrate may be an inorganic glass plate. The material of the substrate may be resin such as (meth)acrylic resin, cellulose triacetate resin, polycarbonate, and amorphous polyolefin. That is, the substrate may be a resin glass plate. The substrate may have multiple layers. The thickness of the substrate is, for example, 1 mm or more and 5 mm or less. The pair of substrates may be identically configured with the same material, or may be configured with different materials.

<Bonding material>
The bonding material is disposed between the pair of substrates. In laminated glass, a layer formed by the bonding material is also called an "interlayer film." The bonding material is transparent. The bonding material has adhesive or cohesive properties. The bonding material is in contact with each of the pair of substrates and bonds the pair of substrates to each other. In FIG. 7, the bonding material 70 is filled between the pair of substrates 60, 62. That is, the bonding material 70 is disposed between the pair of substrates 60, 62 with no gaps. The thickness of the bonding material is, for example, 20 μm or more and 1000 μm or less.

In one embodiment, the bonding material contains a thermoplastic resin.
Examples of the thermoplastic resin include polyvinyl acetal, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-propylene hexafluoride copolymer, polytrifluoroethylene, acrylonitrile-butadiene-styrene copolymer, polyester, polyether, polyamide, polycarbonate, polyurethane, polyvinyl chloride, polyethylene, polypropylene, polystyrene, poly(meth)acrylate, and ethylene-(meth)acrylic acid copolymer. Among these, polyvinyl acetal and ethylene-vinyl acetate copolymer are preferred, and polyvinyl acetal is more preferred. As the polyvinyl acetal, polyvinyl butyral is preferred. That is, polyvinyl butyral (PVB) is preferred as the thermoplastic resin constituting the bonding material.
The bonding material may contain one or more thermoplastic resins.

The bonding material may contain a plasticizer in order to further increase the adhesive strength of the bonding material to the substrate or the like. In one embodiment, the plasticizer is a liquid plasticizer. In one embodiment, the bonding material contains a thermoplastic resin and a plasticizer, may contain polyvinyl acetal and a plasticizer, or may contain polyvinyl butyral and a plasticizer.

Plasticizers include those commonly used in interlayer films for laminated glass, such as ester-based plasticizers, such as monobasic organic acid esters and polybasic organic acid esters; and phosphate-based plasticizers, such as organic phosphate compounds and organic phosphite compounds.

The content of the plasticizer in the bonding material may be 10 parts by mass or more, 20 parts by mass or more, or 80 parts by mass or less, or 70 parts by mass or less, per 100 parts by mass of the thermoplastic resin. This can, for example, further improve the adhesion and transparency of the bonding material.

The bonding material may contain one or more additives. Examples of additives include adhesion regulators, antioxidants, light stabilizers, flame retardants, antistatic agents, moisture-resistant agents, pigments, dyes, fluorescent whitening agents, ultraviolet shielding agents, heat ray reflecting agents, and heat ray absorbing agents.

The bonding material may have a single layer structure or a multi-layer structure.

The bonding material can be formed, for example, by kneading the components that make up the bonding material to prepare a composition, and then using the composition to form a film. For example, the composition can be formed into a sheet-like film by a conventional film-forming method such as an extrusion method, a calendar method, or a press method.

<Hologram sheet>
The hologram sheet of the present disclosure is, for example, disposed between a pair of substrates. The hologram sheet may be disposed so as to be in contact with a bonding material. The hologram sheet may be disposed, for example, in the center between the pair of substrates and surrounded by a bonding material (see FIG. 7). However, the present disclosure is not limited to this, and the hologram sheet may be disposed on one of the substrates without a bonding material and in contact with the one of the substrates, or may be disposed on one of the substrates via an adhesive layer.

<Adhesive Layer>
An adhesive layer may be provided between each layer of the combiner.
Examples of adhesives that constitute the adhesive layer include elastomer-based adhesives such as natural rubber-based, reclaimed rubber-based, chloroprene rubber-based, nitrile rubber-based, styrene-butadiene rubber-based, and thermoplastic elastomer-based adhesives; synthetic resin-based adhesives such as epoxy resin-based and polyurethane-based adhesives; chemically reactive adhesives such as reactive acrylic and cyanoacrylate-based adhesives; ultraviolet-curing adhesives and electron beam-curing adhesives; hot-melt adhesives such as ethylene-vinyl acetate copolymer resin-based, polyamide-based, polyester-based, thermoplastic elastomer-based, and reactive hot-melt-based adhesives; aqueous adhesives such as water-soluble adhesives, emulsion-based adhesives, and latex-based adhesives; and inorganic adhesives.

The thickness of the adhesive layer is, for example, 0.1 μm or more and 10 μm or less.

<Method of manufacturing combiner>
A manufacturing method for a combiner of the present disclosure includes, for example, a preparation process for preparing a pair of substrates, a bonding material, and a hologram sheet of the present disclosure, an arrangement process for arranging the bonding material and the hologram sheet between the pair of substrates, and a bonding process for bonding the pair of substrates together.

The preparation process includes a process of preparing a pair of substrates, a process of preparing a bonding material, and a process of preparing the hologram sheet of the present disclosure. In the process of preparing a pair of substrates, a pair of substrates made of glass or the like is prepared.

Then, a placement process is performed. In the placement process, a bonding material and a hologram sheet are placed between the pair of substrates. The bonding material is placed so as to be in contact with each of the pair of substrates. The hologram sheet may be placed in the center of the pair of substrates in a plan view. The hologram sheet may be placed so as to be in contact with the bonding material. The hologram sheet may be placed so as to be surrounded by the bonding material. The bonding material is filled between the pair of substrates. The bonding material is placed without any gaps between the pair of substrates.

Next, a bonding process is performed. In the bonding process, the pair of substrates are bonded together. More specifically, the pair of substrates are pressurized from the outside in a vacuum atmosphere. The temperature during pressurization may be 80°C or higher, 100°C or higher, or 200°C or lower, or 150°C or lower. As a result, the bonding material is fused to each of the pair of substrates, and the pair of substrates are bonded (bonded) together.

This way you can get a combiner.

<Combiner of Other Embodiments>
In another embodiment, the combiner of the present disclosure may include a base material, a hologram layer, and a substrate in this order. The combiner may include an adhesive layer between the hologram layer and the substrate. The details of each layer are as described above, and will not be described here.

Examples of the substrate include a resin substrate and a glass substrate. Examples of the resin substrate include a polycarbonate substrate, a polyester substrate such as a polyethylene terephthalate substrate, a polybutylene terephthalate substrate, and a polyethylene naphthalate substrate, and a (meth)acrylic resin substrate such as a polymethyl methacrylate substrate.
The thickness of the substrate is, for example, not less than 1 mm and not more than 5 mm.

The combiner of the other embodiments described above can be manufactured, for example, by bonding the hologram sheet of the present disclosure to a substrate, optionally via an adhesive layer.

[Embodiment]
The present disclosure relates to, for example, the following [1] to [13].
[1] A photosensitive composition for forming a hologram layer, comprising: a radical polymerizable monomer (1) represented by the above-mentioned formula (1); a radical polymerizable monomer (2) other than the radical polymerizable monomer (1); a binder resin; a photopolymerization initiator; and a sensitizing dye.
[2] The photosensitive composition according to [1], wherein the radical polymerizable monomer (2) is at least one selected from the group consisting of a (meth)acrylate compound having a refractive index of 1.50 or more and a thio(meth)acrylate compound having a refractive index of 1.50 or more.
[3] The photosensitive composition according to [1] or [2] above, further comprising a cationic polymerizable monomer.
[4] A hologram recording sheet comprising, in this order, a substrate, a photosensitive material layer formed from the photosensitive composition according to any one of [1] to [3] above, and a first protective layer.
[5] A hologram sheet comprising, in this order, a substrate, a hologram layer formed from the photosensitive composition according to any one of [1] to [3] above, and a first protective layer.
[6] The hologram sheet according to [5], wherein the hologram layer is a volume hologram layer.
[7] A combiner comprising a base material, a hologram layer formed from the photosensitive composition according to any one of [1] to [3] above, and a substrate, in this order.
[8] The combiner according to [7], wherein the hologram layer is a volume hologram layer.
[9] A combiner having a pair of substrates, a bonding material arranged between the pair of substrates so as to bond the pair of substrates to each other, and a hologram sheet described in [5] or [6] positioned between the pair of substrates.
[10] A head-up display comprising: an image forming device that emits image light; and a combiner according to any one of [7] to [9], to which the image light is irradiated.
[11] A moving object comprising the head-up display according to [10].
[12] A hologram layer having a structure represented by the above formula (1A).
[13] The hologram layer according to the above [12], wherein the refractive index modulation amount (Δn) is 0.025 or more.

The photosensitive composition, hologram recording sheet, hologram sheet, and combiner of the present disclosure will be described in more detail below with reference to examples.

The radical polymerizable monomers used in the examples will be described below.
・TBIS-ZPC
TBIS-ZPC, manufactured by Taoka Chemical
Compound represented by the following formula Refractive index (589 nm: D line, 25° C.): 1.634

・EA-0200
Osaka Gas Chemicals, OGSOL EA-0200
A compound represented by the following formula (m=n=1-2):
Refractive index (589 nm: D line, 25° C.): 1.605

・RUVA-93
RUVA-93, manufactured by Otsuka Chemical
Compound represented by the following formula Refractive index (589 nm: D line, 25° C.): 1.625

・NMT-A
Kyoeisha Chemical Company, Light Acrylate NMT-A
1-Naphthyl methyl acrylate Refractive index (589 nm: D line, 25°C): 1.602

・A-BP-2EO
Honshu Chemical Industry Co., Ltd., A-BP-2EO
Compound represented by the following formula Refractive index (589 nm: D line, 25° C.): 1.511

・6MDNTMA
Made by Sugai Chemical Industry, 6MDNTMA
6-Methacryloyloxymethyldinaphthothiophene Refractive index (589 nm: D line, 25°C): 1.726

・16NDSHMA
Made by Sugai Chemical Industry, 16NDSHMA
Compound represented by the following formula Refractive index (589 nm: D line, 25° C.): 1.650

・A-LEN-10
Shin-Nakamura Chemical Co., Ltd., NK Ester A-LEN-10
Ethoxylated o-phenylphenol acrylate (n=1-2)
Refractive index (589 nm: D line, 25° C.): 1.558

・POB-A
Kyoeisha Chemical Company, Light Acrylate POB-A
m-Phenoxybenzyl acrylate Refractive index (589 nm: D line, 25°C): 1.566

HDD A
1,6-Hexanediol diacrylate Refractive index (589 nm: D line, 25°C): 1.456

[Example 1]
A photosensitive composition for volume hologram recording was prepared using the materials shown below.
Cationic polymerizable group-containing (meth)acrylic resin: 50 parts by mass (poly(isobutyl methacrylate/methyl methacrylate/glycidyl methacrylate/=50/40/10) copolymer, polystyrene equivalent weight average molecular weight: 130,000, refractive index: 1.422)
Radical polymerizable monomer TBIS-ZPC 40 parts by weight RUVA-93 10 parts by weight Cationic polymerizable monomer 1,6-hexanediol diglycidyl ether 40 parts by weight (EX-212 manufactured by Nagase ChemteX, refractive index: 1.460)
Diaryliodonium salt (PI2074, manufactured by Rhodia) 5 parts by weight 3,3',9-triethyl-2,2'-(4,5,4',5'-dibenzo)thiacarbocyanine bromide 0.5 parts by weight 3,3',9-triethyl-2,2'-thiacarbocyanine iodide 0.5 parts by weight 3-(2-benzimidazolyl)-7-(diethylamino)coumarin 0.5 parts by weight 1-butanol 65 parts by weight Methyl ethyl ketone 115 parts by weight

[Examples 2 to 14 and Comparative Examples 1 to 3]
Photosensitive compositions for volume hologram recording were prepared in the same manner as in Example 1, except that the types and blending ratios of the radical polymerizable monomers were changed as shown in Table 1. Table 1 shows the blending ratio (mass%) of each radical polymerizable monomer relative to 100 mass% of the total amount of the radical polymerizable monomers.

[Preparation of Hologram Recording Sheet]
A polyethylene terephthalate (PET) film with a thickness of 50 μm was prepared. The above-mentioned photosensitive composition was applied to the surface of the PET film and dried at 100° C. for 10 minutes to form a photosensitive material layer with a thickness of 15 μm. A release PET film with a thickness of 38 μm (SP-PET-O3-38BU manufactured by Mitsui Tohcello) was attached to the photosensitive material layer. In this manner, a hologram recording sheet including a PET film, a photosensitive material layer, and a release PET film was produced.

<Preparation of hologram sheet>
The sheet obtained by peeling off the release PET film from the hologram recording sheet was attached to the mirror so that the photosensitive material layer was in contact with the mirror. In this way, an intermediate laminate including a PET film, a photosensitive material layer, and a mirror was produced. Holographic exposure was performed by irradiating the intermediate laminate with 460 nm, 532 nm, and 640 nm laser light from the PET film side with a total exposure amount of 80 mJ/ ^cm2 and an incident angle of 0°, and a volume hologram was recorded in the photosensitive material layer. After the holographic exposure, the mirror was removed from the intermediate laminate, and a 50 μm thick PET film (Cosmoshine A4360 manufactured by Toyobo) was attached to the photosensitive material layer, and heat treatment was performed at 80 ° C for 10 minutes. Further, the entire surface of the photosensitive material layer was irradiated with ultraviolet light so that the irradiation energy amount on the surface of the photosensitive material layer was 1200 mJ/ ^cm2 , and further, the entire surface of the photosensitive material layer was irradiated with light from a fluorescent lamp for 10 minutes to cause fading of the sensitizing dye. In this way, a hologram layer was formed from the photosensitive material layer. In this way, a hologram sheet including a PET film, a hologram layer, and a PET film was obtained.

<Making a combiner>
A first substrate and a second substrate were used as a pair of substrates. The thickness of the first substrate along the normal direction was 2 mm. Soda lime glass was used as the first substrate. The thickness of the second substrate along the normal direction was 2 mm. Soda lime glass was used as the second substrate. A polyvinyl butyral resin material was used as the bonding material. The thickness of the bonding material between the hologram sheet and the first substrate was 380 μm. The thickness of the bonding material between the hologram sheet and the second substrate was 380 μm.

The first and second substrates have a square shape of 150 mm x 150 mm when viewed from the normal direction. The hologram sheet has a square shape of 100 mm x 100 mm when viewed from the normal direction. The hologram sheet was placed against the first and second substrates in the bonding material such that the periphery of the hologram sheet was located 25 mm inward from the periphery of the first and second substrates.
In this way, a combiner was obtained.

[Measurement of average diffraction efficiency and refractive index modulation (Δn)]
The transmittance of the hologram sheet obtained above was measured using a spectrophotometer (Shimadzu Corporation's "UV-3100PC", compliant with JIS K0115:2020) to obtain a transmission spectrum. In the obtained transmission spectrum, the peak transmittance A and the base transmittance B were determined and expressed by the following formula:
Diffraction efficiency η={|B−A|/B}×100(%)
The diffraction efficiency η for each color (blue, green, red) and its average value were calculated.
Using the obtained value of the diffraction efficiency η, the following Kogelnik theoretical formula:
η=tanh ² (π(Δn)d/λcosθ ₀ )
(In the formula, η is the diffraction efficiency, d is the thickness of the photosensitive material layer, λ is the recording laser wavelength, and θ ₀ is the incident angle of the recording laser light into the photosensitive material layer.)
The refractive index modulation amount (Δn) was calculated by the above, and the Δn values of each color (blue, green, red) were summed up.

In the examples, a hologram layer is formed with an average diffraction efficiency of 40% or more and a refractive index modulation amount (Δn) of 0.040 or more. In the comparative examples, a hologram layer that diffracts (reflects) image light to display an image is not formed, or a hologram layer is formed with an average diffraction efficiency of less than 40% and/or a refractive index modulation amount (Δn) of less than 0.040.

Although the photosensitive composition etc. of the present disclosure has been described above with reference to specific examples, the above-mentioned specific examples are not intended to limit the photosensitive composition etc. of the present disclosure. The photosensitive composition etc. of the present disclosure described above can be embodied in various other specific examples, and various omissions, substitutions, changes, and additions can be made without departing from the gist of the present disclosure.

1: Hologram recording sheet 2: Hologram sheet 10: Substrate 10a: First surface of substrate 10b: Second surface of substrate 20: Photosensitive material layer 20a: First surface of photosensitive material layer 20b: Second surface of photosensitive material layer 22: Hologram layer 22a: First surface of hologram layer 22b: Second surface of hologram layer 30: First protective layer 40: Second protective layer 60, 62: Substrate 70: Bonding material 101: Mobile body 102: Head-up display 103: Image forming device 104: Combiner 105: User 106: Observation position

Claims (13)

A radical polymerizable monomer (1) represented by the following formula (1),
A radical polymerizable monomer (2) other than the radical polymerizable monomer (1),
A binder resin;
A photopolymerization initiator;
A sensitizing dye;
Contains
For forming a hologram layer,
Photosensitive composition.
[In the formula (1), R ¹ to R ⁴ each independently represent an alkyl group, a cycloalkyl group, an aryl group, or a halogen atom, k1 to k4 each independently represent an integer of 0 to 5, and when at least one of k1 to k4 is 2 or more, the corresponding R ¹ to R ⁴ may be the same or different, n1 and n2 each independently represent an integer of 1 or more, R ⁵ and R ⁶ each independently represent an alkanediyl group having 2 to 4 carbon atoms, p1 and p2 each independently represent an integer of 0 or 1 or more, and R ⁷ and R ⁸ each independently represent a hydrogen atom or a methyl group.] The photosensitive composition according to claim 1, wherein the radical polymerizable monomer (2) is at least one selected from a (meth)acrylate compound having a refractive index of 1.50 or more and a thio(meth)acrylate compound having a refractive index of 1.50 or more. The photosensitive composition according to claim 1, further comprising a cationic polymerizable monomer. A substrate;
A photosensitive material layer formed from the photosensitive composition according to any one of claims 1 to 3;
A first protective layer; and
A hologram recording sheet comprising: A substrate;
A hologram layer formed from the photosensitive composition according to any one of claims 1 to 3;
A first protective layer; and
A hologram sheet comprising: The hologram sheet according to claim 5, wherein the hologram layer is a volume hologram layer. A substrate;
A hologram layer formed from the photosensitive composition according to any one of claims 1 to 3;
A substrate;
A combiner having the above in this order. The combiner of claim 7, wherein the hologram layer is a volume hologram layer. A pair of substrates;
a bonding material disposed between the pair of substrates so as to bond the pair of substrates to each other;
The hologram sheet according to claim 5 , which is located between the pair of substrates;
A combiner having an image forming device that emits image light;
A combiner according to claim 9 , which is irradiated with the image light;
Equipped with a head-up display. A moving object equipped with the head-up display according to claim 10. A hologram layer having a structure represented by the following formula (1A):
[In the formula (1A), R ¹ to R ⁴ each independently represent an alkyl group, a cycloalkyl group, an aryl group, or a halogen atom; n1 and n2 each independently represent an integer of 1 or more; k1 to k4 each independently represent an integer of 0 or more and 5 or less; when at least one of k1 to k4 is 2 or more, the corresponding R ¹ to R ⁴ may be the same or different; R ⁵ and R ⁶ each independently represent an alkanediyl group having 2 to 4 carbon atoms; p1 and p2 each independently represent an integer of 0 or 1 or more; and R ⁷ and R ⁸ each independently represent a hydrogen atom or a methyl group.] The hologram layer according to claim 12, wherein the refractive index modulation amount (Δn) is 0.025 or more.