Mixed composition, and film, optical component, and image display device using same

Abstract

Provided are: a mixed composition capable of increasing a refractive index difference between regions having different refractive indices when forming a film having regions having different refractive indices in a plane; and a film, an optical component, and an image display device using the same. This mixed composition comprises: a photopolymerizable aliphatic monomer having a refractive index of less than 1.50 at a wavelength of sodium D-lines at 25ºC; and a polymer having a refractive index of at least 1.60 at a wavelength of sodium D-lines at 25ºC. 40-300 parts by mass of the photopolymerizable aliphatic monomer may be blended with respect to 100 parts by mass of the polymer. The number of photopolymerizable groups per molecule of the photopolymerizable aliphatic monomer may be at most 4.

Description

Mixed Composition, Film Using the Same, Optical Component, and Image Display Device

[0001] The present invention relates to a mixed composition, a film using the same, an optical component, and an image display device.

[0002] In an image display device, a diffraction grating or a holographic optical element may be used as an optical component. As a material for forming such an optical component, for example, Patent Document 1 below discloses a composition containing a polymer such as polyvinyl acetate and a photopolymerizable monomer such as fluorene-based acrylate.

[0003] Patent Document 2 below discloses a photopolymer composition containing a polymer matrix or a precursor thereof, a photoreactive monomer composed of a polyfunctional (meth)acrylate monomer having a refractive index of 1.5 or more or a monofunctional (meth)acrylate monomer having a refractive index of 1.5 or more, and a low refractive index fluorine-based compound having a refractive index of less than 1.45.

[0004] International Publication No. 2021 / 006011, Japanese Patent Application Laid-Open No. 2020-515910

[0005] However, both the composition described in Patent Document 1 and the photopolymer composition described in Patent Document 2 had room for improvement regarding the refractive index difference between regions having different refractive indexes in the plane when forming a film having regions with different refractive indexes in the plane.

[0006] Therefore, an object of the present invention is to provide a mixed composition capable of making the refractive index difference larger.

[0007] To solve the above problems, the present invention provides the following mixed compositions, a film using the same, an optical component and an image display device. [1] A mixed composition comprising a photopolymerizable aliphatic monomer having a refractive index of less than 1.50 at the wavelength of sodium D lines at 25°C and a polymer having a refractive index of 1.60 or more at the wavelength of sodium D lines at 25°C. [2] The mixed composition according to [1], wherein the photopolymerizable aliphatic monomer is blended in a ratio of 40 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the polymer. [3] The mixed composition according to [1] or [2], wherein the number of photopolymerizable groups per molecule of the photopolymerizable aliphatic monomer is 4 or less. [4] The mixed composition according to any one of [1] to [3], wherein the molecular weight of the photopolymerizable aliphatic monomer is 600 or less. [5] The mixed composition according to any one of [1] to [4], wherein the polymer has a ring structure in its side chain that has aromaticity according to Hückel's rule and has 4N+2 (where N is an integer of 3 or more) π electrons. [6] The mixed composition according to any one of [1] to [5], wherein the polymer has at least one ring structure selected from the group consisting of heterocyclic rings and aromatic rings bonded to heteroatoms in its side chains. [7] The mixed composition according to any one of [1] to [6], wherein the weight-average molecular weight of the polymer is 25,000 or less. [8] A film comprising the mixed composition according to any one of [1] to [7]. [9] A film obtained using the mixed composition according to any one of [1] to [7], wherein the film has two or more regions with different refractive indices in its plane, and the difference in refractive index between the regions is 0.001 or more.

[10] An optical component comprising the film according to [8] or [9].

[11] An image display device having the optical component according to

[10] .

[0008] According to the present invention, it is possible to provide a mixed composition that can increase the refractive index difference between regions with different refractive indices when a film having regions with different refractive indices in its surface is formed, as well as a film using the same, an optical component, and an image display device.

[0009] This is a schematic plan view showing one embodiment of the film of the present invention. This is a schematic diagram showing a light guide plate type AR glasses, which is one embodiment of the image display device of the present invention.

[0010] Hereinafter, an embodiment of the present invention will be described in detail, with reference to the drawings as appropriate. [Mixed Composition] The mixed composition of the present invention comprises a photopolymerizable aliphatic monomer having a refractive index of less than 1.50 at the wavelength of the sodium D line at 25°C, and a polymer having a refractive index of 1.60 or more at the wavelength of the sodium D line at 25°C. According to the above mixed composition, when a film having regions with different refractive indices (e.g., exposed and unexposed regions) in a plane is formed, the refractive index difference between regions with different refractive indices can be increased, and the clarity of the boundary between regions with different refractive indices can be improved.

[0011] The reason why the mixed composition of the present invention produces the above-mentioned effects is not entirely clear, but the inventors surmise that it is as follows. That is, for example, when the mixed composition of the present invention is formed in the form of a film on a substrate and this film-like mixed composition is exposed to light, the photopolymerizable aliphatic monomer polymerizes in the exposed area, and the concentration of the photopolymerizable aliphatic monomer decreases. At this time, unlike photopolymerizable aromatic monomers, photopolymerizable aliphatic monomers do not have π electrons and do not undergo π-π electron interactions like photopolymerizable aromatic monomers, so they move more easily within the polymer than photopolymerizable aromatic monomers. Therefore, the photopolymerizable aliphatic monomer present in the unexposed area easily diffuses and migrates to the exposed area over time, and the migrated photopolymerizable aliphatic monomer polymerizes one after another. In this way, the concentration of photopolymerizable aliphatic monomer decreases sufficiently in the unexposed area, while the concentration of the photopolymerized aliphatic monomer increases in the exposed area. As a result, a film is formed having regions with different refractive indices (exposed and unexposed areas) within the plane, and the refractive index difference between the regions with different refractive indices tends to become large.

[0012] The mixed composition of the present invention will be described in detail below.

[0013] <Polymer> The refractive index of the polymer contained in the mixed composition of the present invention is 1.60 or higher at the wavelength of the sodium D line (589 nm) at 25°C. The refractive index of the polymer is the value measured from the reflection spectrum of the polymer coating film on the substrate using the minimum angle deviation method, Abbe refractometer, or spectroscopic ellipsometry. The method for calculating from the reflection spectrum on the substrate is as follows: For a substrate on which a polymer coating film has been formed, the transmission spectrum and reflection spectrum at wavelengths from 300 nm to 800 nm are measured using a visible ultraviolet spectrophotometer (e.g., "V-650" manufactured by JASCO Corporation) equipped with an integrating sphere unit (e.g., "ISV-922" manufactured by JASCO Corporation). Next, the true reflectance spectrum is obtained by smoothing the transmission spectrum and the reflectance spectrum by subtracting the increase or decrease due to interference in the reflectance spectrum. From the value of the sodium D line (wavelength 589 nm) at 25°C and the refractive index of the substrate, the refractive index of the polymer coating film at 25°C (wavelength 589 nm) is calculated based on Fresnel's formula (for example, Hecht Optics I, 5th edition, Maruzen Publishing, 2018, pp. 209-226). This allows the refractive index of the polymer coating film at the wavelength of the sodium D line (wavelength 589 nm) at 25°C to be determined. The refractive index of the polymer is preferably 1.61 or higher, more preferably 1.63 or higher, and even more preferably 1.65 or higher. A refractive index of 1.60 or higher allows for a larger refractive index difference between regions with different refractive indices formed within the plane of the polymer coating film, thereby improving the clarity of the boundaries between regions with different refractive indices. The refractive index of the polymer may be 1.80 or lower, 1.75 or lower, or 1.70 or lower.

[0014] The polymer is not particularly limited as long as it has a refractive index of 1.60 or higher at the wavelength of the sodium D line of 589 nm at 25°C. However, it is preferable that the side chain has at least one ring structure selected from the group consisting of heterocycles and aromatic rings bonded to heteroatoms, and it is more preferable that it has a heterocycle. In this case, it is easier to impart a refractive index of 1.60 or higher to the polymer. Furthermore, it is preferable that the side chain has a ring structure that has aromaticity according to Hückel's rule and has 4N+2 π electrons (where N is an integer of 1 or more). N is preferably 2 or more, and more preferably 3 or more. In this case, it is easier to impart a refractive index of 1.60 or higher to the polymer. A heterocycle is a ring structure in which an atom other than carbon (e.g., nitrogen, oxygen, sulfur, etc.) is included as part of the ring. Examples of heterocycles include pyridine rings, furan rings, thiophene rings, indole rings, pyrrole rings, imidazole rings, piperidine rings, quinoline rings, isoquinoline rings, and pyrimidine rings, as well as rings in which aromatic rings are fused to these rings. It is preferable that the heterocycles possess aromaticity according to Hückel's rule. Specifically, it is preferable that the heterocycles have 4N + 2 (where N is an integer of 1 or more) π electrons. N is preferably 2 or more, and more preferably 3 or more. Specific examples of heterocycles with N 2 or more include carbazole rings, benzimidazole rings, benzothiazole rings, naphthothiophene rings, and dinaphthothiophene rings. A heteroatom is an atom other than a carbon atom. Examples of heteroatoms include oxygen atoms, sulfur atoms, and nitrogen atoms. From the viewpoint of easily imparting a refractive index of 1.60 or more to the polymer, preferred heteroatoms are nitrogen atoms or sulfur atoms, and more preferred heteroatoms are nitrogen atoms. The aromatic ring bonded to the heteroatom preferably has aromaticity according to Hückel's rule. That is, the aromatic ring bonded to the heteroatom preferably has 4N + 2 (where N is an integer of 1 or more) π electrons. N is preferably 2 or more, and more preferably 3 or more. Examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, and fluorene rings. Specific examples of aromatic rings with N 2 or more include fused rings such as naphthalene rings, anthracene rings, and fluorene rings.

[0015] The polymer may or may not have acidic groups in its side chains, but it is preferable that it does. In this case, the solubility of the polymer in polar solvents such as alcohols, ketones, and esters is improved.

[0016] The polymer may or may not have ester groups in its side chains, but it is preferable that it does. In this case, it is easier to adjust the compatibility with photopolymerizable aliphatic monomers having photopolymerizable groups. The ester group is represented as -COOR. Here, R is a monovalent group having a structure in which a linear or branched unsaturated aliphatic hydrocarbon is epoxidized, a monovalent group having a structure in which an unsaturated alicyclic hydrocarbon is epoxidized, and a linear or branched monovalent unsaturated aliphatic hydrocarbon group. Among these, from the viewpoint of excellent storage stability of the mixed composition, a monovalent group having a structure in which an unsaturated alicyclic hydrocarbon is epoxidized is preferred. The polymer may also have multiple ester groups. In the case of multiple ester groups, R may be the same or different from each other. Examples of monovalent groups having a structure in which a linear or branched unsaturated aliphatic hydrocarbon is epoxidized include glycidyl groups, β-methylglycidyl groups, and β-ethylglycidyl groups. Examples of monovalent groups having an epoxidized structure of an unsaturated alicyclic hydrocarbon include the monovalent group represented by formula (I) and the monovalent group represented by formula (II). The polymer may have both the monovalent group represented by formula (I) and the monovalent group represented by formula (II).

[0017]

[0018] The polymer preferably has a first structural unit having at least one of a heterocycle and an aromatic ring bonded to a heteroatom in its side chain, a second structural unit having an acidic group in its side chain, and a third structural unit having an ester group in its side chain. This polymer can achieve both a high refractive index and solubility in solvents. The proportion of the first structural unit to the total number of the first, second, and third structural units is preferably 60% or more. The proportion of the first structural unit may be 70% or more, or 80% or more. The proportion of the second structural unit to the total number of the first, second, and third structural units is preferably 5% or more. The proportion of the second structural unit may be 10% or more, or 20% or more. The proportion of the second structural unit may be 40% or less, or 30% or less. The proportion of the third structural unit to the total number of the first, second, and third structural units is preferably 5% or more. The proportion of the third structural unit may be 10% or more, or 20% or more. The proportion of the third structural unit may be 20% or less, or 15% or less.

[0019] Examples of polymer main chains include carbon chains and PEG (polyethylene glycol) chains, but carbon chains are preferred. In this case, an advantage is obtained in that the number of solvents that can be simultaneously compatible with aliphatic monomers and polymers increases.

[0020] The weight-average molecular weight (hereinafter also referred to as "Mw") of the polymer is not particularly limited, but is preferably 50,000 or less. A polymer Mw of 50,000 or less reduces the viscosity of the mixed composition, making it easier for the photopolymerizable aliphatic monomer to migrate from the unexposed areas to the exposed areas during exposure. Mw refers to the value measured by GPC using standard polystyrene as the molecular weight standard. The polymer Mw is more preferably 40,000 or less, even more preferably 30,000 or less, and particularly preferably 25,000 or less. The polymer Mw may be 1,000 or more, 5,000 or more, 6,000 or more, 7,000 or more, or 8,000 or more. The polymer Mw is preferably 2,000 or more, more preferably 5,000 or more, and even more preferably 6,000 or more.

[0021] <Photopolymerizable Aliphatic Monomers> The photopolymerizable aliphatic monomers contained in the mixed composition of the present invention are aliphatic monomers having a photopolymerizable group. A photopolymerizable group is a group that can participate in the photopolymerization reaction by reactive species generated from the photopolymerization initiator, such as active radicals or acids. Examples of photopolymerizable groups include vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, (meth)acryloyl groups, (meth)acryloyloxy groups, oxyranyl groups, oxetanyl groups, epoxy groups, etc. Among these, (meth)acryloyl groups and (meth)acryloyloxy groups are preferred, and (meth)acryloyl groups are more preferred, from the viewpoint of easily forming regions with different refractive indices within the plane. The reason why the above effects are achieved is not necessarily clear, but the inventors speculate that it is as follows. That is, the polymerization efficiency of the photopolymerizable aliphatic monomer can be increased when the mixed composition is exposed to light, and the concentration of the photopolymerizable aliphatic monomer tends to decrease. As a result, it becomes easier to form a film that has regions with different refractive indices (exposed and unexposed areas) within its surface.

[0022] The refractive index of photopolymerizable aliphatic monomers at 25°C at the wavelength of the sodium D line (589 nm) is less than 1.50. When the refractive index of a photopolymerizable aliphatic monomer is less than 1.50, the refractive index difference between regions with different refractive indices (e.g., exposed and unexposed areas) can be increased when forming a film with regions of different refractive indices within the plane, thereby improving the clarity of the boundaries between these regions. The refractive index of a photopolymerizable aliphatic monomer is measured from the reflection spectrum of the monomer coating on a substrate using the minimum deflection method, Abbe refractometer, or spectroscopic ellipsometry. The method for calculating the refractive index from the reflection spectrum on the substrate is as follows: For a substrate on which a monomer coating has been formed, the transmission spectrum and reflection spectrum from 300 nm to 800 nm are measured using a visible-ultraviolet spectrophotometer (e.g., "V-650" from JASCO Corporation) equipped with an integrating sphere unit (e.g., "ISV-922" from JASCO Corporation). Next, the true reflection spectrum, obtained by smoothing the transmission spectrum and reflection spectrum by subtracting the increase or decrease due to interference in the reflection spectrum, is used to calculate the refractive index of the monomer-coated film at the wavelength of the sodium D line (589 nm) at 25°C based on the value at 589 nm and the refractive index of the substrate, using Fresnel's formula (for example, Hecht Optics I, 5th edition, Maruzen Publishing, 2018, pp. 209-226). This allows us to determine the refractive index of the monomer-coated film at the wavelength of the sodium D line (589 nm) at 25°C. The refractive index of the photopolymerizable aliphatic monomer is preferably 1.49 or less, more preferably 1.48 or less, and even more preferably 1.47 or less. From the viewpoint of good compatibility between the photopolymerizable aliphatic monomer and the polymer, the refractive index of the photopolymerizable aliphatic monomer may be 1.30 or more, or 1.40 or more. The absolute value of the difference between the refractive index of the polymer and the refractive index of the photopolymerizable aliphatic monomer should be greater than 0, but preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.15 or more.

[0023] The number of photopolymerizable groups per molecule of photopolymerizable aliphatic monomer is not particularly limited as long as it is one or more, but is preferably six or less, more preferably four or less, and even more preferably two or less. When the number of photopolymerizable groups is four or less, when a film is formed having regions with different refractive indices in the plane (e.g., exposed and unexposed regions), the refractive index difference between the regions with different refractive indices can be made larger, and the clarity of the boundary between regions with different refractive indices can be improved. The reason why the above effects are achieved is not necessarily clear, but the inventors speculate that it may be as follows. That is, when the number of photopolymerizable groups is small, there are fewer reaction sites per molecule, so when the mixed composition is exposed, compounds with low steric hindrance are more easily generated. As a result, the photopolymerizable aliphatic monomer is more likely to move from the unexposed region to the exposed region, and as a result, regions with different refractive indices are more easily formed in the plane.

[0024] Examples of photopolymerizable aliphatic monomers having one acryloyl group and a refractive index of less than 1.50 include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxydipropylene glycol acrylate, butoxyethyl acrylate, butoxydiethylene glycol acrylate, butyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methoxy- Ethylene glycol acrylate, methoxy-diethylene glycol acrylate, methoxy PEG #200 acrylate, methoxy PEG #400 acrylate, methoxy PEG #600 acrylate, methoxy PEG #1000 acrylate, methoxy-polyethylene glycol acrylate, 2-acryloyloxyethyl succinic acid, acrylic acid, dimethylamino acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, cyclohexyl acrylate, isobornyl acrylate, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, etc. can be used. These can be used individually or in combination of two or more.

[0025] As photopolymerizable aliphatic monomers having two acryloyl groups and a refractive index of less than 1.50, for example, PEG #400 diacrylate, tripropylene glycol diacrylate (TPGDA), PEG #600 diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, polytetramethylene glycol diacrylate, neopentyl glycol diacrylate, neopentyl glycol hydroxypivalate diacrylate, glycerin diacrylate, 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl) bisacrylic acid, glycerin 1,3-diglycerolate diacrylate, etc., can be used. These can be used individually or in combination of two or more.

[0026] As photopolymerizable aliphatic monomers having three or more acryloyl groups and a refractive index of less than 1.50, for example, trifunctional (alkoxylated) trimethylolpropane acrylate (A-GLY-9E), trimethylolpropane ethoxytriacrylate (EBECRYL 160S), dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, glycerin triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, etc., can be used. These can be used individually or in combination of two or more.

[0027] The molecular weight of the photopolymerizable aliphatic monomer is not particularly limited, but is preferably 1000 or less, more preferably 800 or less, and even more preferably 600 or less. Here, molecular weight refers to the average molecular weight when the photopolymerizable aliphatic monomer has repeating units, and the average molecular weight is a value measured by methods such as LC / MS. When the molecular weight of the photopolymerizable aliphatic monomer is 600 or less, the photopolymerizable aliphatic monomer is more likely to migrate from the unexposed areas to the exposed areas when the mixed composition is exposed, and when a film is formed having regions with different refractive indices in the plane (e.g., exposed and unexposed areas), the refractive index difference between the regions with different refractive indices can be made larger, and the clarity of the boundary between the regions with different refractive indices can be improved. The molecular weight of the photopolymerizable aliphatic monomer is preferably 100 or more.

[0028] The blending ratio of the photopolymerizable aliphatic monomer (hereinafter also referred to as "X") per 100 parts by mass of polymer is not particularly limited, but is preferably 40 parts by mass or more. When X is 40 parts by mass or more, the refractive index difference between regions with different refractive indices (e.g., exposed and unexposed regions) can be made larger when forming a film having regions with different refractive indices in the plane, and the clarity of the boundary between regions with different refractive indices can be further improved. From the viewpoint of making the refractive index difference between regions with different refractive indices larger when forming a film having regions with different refractive indices in the plane (e.g., exposed and unexposed regions), and improving the clarity of the boundary between regions with different refractive indices, X is more preferably 50 parts by mass or more, even more preferably 100 parts by mass or more, and particularly preferably 200 parts by mass or more. From the viewpoint of making it easier for the photopolymerizable aliphatic monomer to migrate from the unexposed region to the exposed region when the mixed composition is exposed, and making the refractive index difference between regions with different refractive indices larger when forming a film having regions with different refractive indices in the plane (e.g., exposed and unexposed regions), and further improving the clarity of the boundary between regions with different refractive indices, X is, for example, 1000 parts by mass or less. X is preferably 700 parts by mass or less, more preferably 500 parts by mass or less, even more preferably 400 parts by mass or less, and particularly preferably 300 parts by mass or less. The reason why the above effects are achieved is not entirely clear, but the inventors surmise that it is as follows. That is, when the blending ratio of photopolymerizable aliphatic monomer to polymer is in the range of 40 parts by mass or more and 1000 parts by mass or less, polymerization reactions proceed more easily when the mixed composition is exposed to light. Furthermore, when the mixed composition is exposed to light, a decrease in the concentration of photopolymerizable aliphatic monomer in the unexposed area is more likely to occur due to the diffusion and migration of photopolymerizable aliphatic monomer present in the unexposed area to the exposed area.

[0029] (Photopolymerization Initiator) The mixed composition of the present invention may further contain a photopolymerization initiator. Any known photopolymerization initiator can be used as the photopolymerization initiator, as long as it is a compound that can initiate the photopolymerization reaction of a photopolymerizable aliphatic monomer. Specifically, examples include photopolymerization initiators that can generate active radicals or acids upon the action of light, and among these, photopolymerization initiators that generate active radicals upon the action of light are preferred. The photopolymerization initiator can be used alone or in combination of two or more types.

[0030] As photopolymerization initiators, known photopolymerization initiators can be used. For example, as photopolymerization initiators that generate active radicals, self-cleaving benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, azo compounds, etc. can be used. Hydrogen abstraction types such as benzophenone compounds, alkylphenone compounds, benzoin ether compounds, benzyl ketal compounds, dibenzosverone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, triazine compounds, etc. can be used. As photopolymerization initiators that generate acid, iodonium salts and sulfonium salts, etc. can be used. Self-cleaving photopolymerization initiators are preferred from the viewpoint of excellent reaction efficiency at low temperatures, and acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are particularly preferred, with oxime ester compounds being more preferred.

[0031] The content of the photopolymerization initiator in the mixed composition can be appropriately adjusted depending on the type and amount of photopolymerizable aliphatic monomer, but is usually 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 8 parts by mass, per 100 parts by mass of the total of the polymer and the photopolymerizable aliphatic monomer. When the content of the photopolymerization initiator is within the above range, the photopolymerization reaction of the photopolymerizable aliphatic monomer can be effectively promoted, and the transition from unexposed areas to exposed areas can be accelerated when the mixed composition is exposed to light.

[0032] (Solvent) The mixed composition of the present invention may further contain a solvent. The further inclusion of a solvent in the mixed composition of the present invention can reduce the viscosity of the mixed composition of the present invention, making it easier to apply. This facilitates the formation of the film of the present invention. The solvent is preferably one that can dissolve the polymer and the photopolymerizable aliphatic monomer, and is preferably a solvent that is inert to the photopolymerization reaction of the photopolymerizable aliphatic monomer.

[0033] Examples of solvents include alcoholic solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone or propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene, and nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; and amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. These solvents may be used individually or in combination of two or more.

[0034] The solvent content is preferably 50 to 98% by mass of the total amount of the mixed composition. In other words, the solid content in the mixed composition is preferably 2 to 50% by mass, and more preferably 5 to 30% by mass. When the solid content is 50% by mass or less, the viscosity of the mixed composition decreases, which tends to result in a more uniform thickness of the film containing the mixed composition or the film obtained using the mixed composition, thus reducing the likelihood of unevenness in the film. Furthermore, the solid content can be determined considering the thickness of the film to be manufactured.

[0035] (Additives) The mixed composition of the present invention may further contain additives as needed, such as polymerization inhibitors, sensitizers, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, ultraviolet absorbers, antioxidants, and dispersants.

[0036] [Film] In one embodiment, the film of the present invention contains the mixed composition described above. The film containing the mixed composition described above refers to a film that has been coated with the mixed composition described above onto a glass substrate or the like, but has not been exposed to light. The film containing the mixed composition described above makes it possible to increase the refractive index difference between regions with different refractive indices when forming a film having regions with different refractive indices within its surface. For example, when a film having regions with different refractive indices (exposed and unexposed areas) within its surface is formed by exposing a part of the film containing the mixed composition described above, the refractive index difference between those regions can be increased. As a result, the clarity of the boundary between regions with different refractive indices can be improved, and excellent diffraction characteristics can be obtained.

[0037] In one embodiment, the film of the present invention is obtained using the mixed composition described above. The film obtained using the mixed composition described above refers to a film obtained by coating the mixed composition described above onto a glass substrate or the like, and then exposing at least a portion of it to light. The film obtained using the mixed composition described above preferably has two or more regions with different refractive indices in its surface, and the difference in refractive index between these regions (hereinafter also referred to as "Δn") is 0.001 or more. Here, the regions with different refractive indices may be adjacent to each other. Furthermore, the regions with different refractive indices may be arranged alternately. For example, regions with high refractive indices and regions with low refractive indices may be arranged alternately.

[0038] Figure 1 is a schematic plan view showing one embodiment of the film of the present invention, and is a view of the film 1 in the direction of its thickness. In the film 1, regions with a high refractive index 2 and regions with a low refractive index 3 are arranged alternately in a stripe pattern along direction X.

[0039] In film 1, the width d1 of the high refractive index region 2 and the width d2 of the low refractive index region 3 may be the same or different. The width d1 of multiple regions 2 may be the same or different. The width d2 of multiple regions 3 may be the same or different. The widths of the high refractive index region 2 or the low refractive index region 3 may be constant or different. If they are not constant, the maximum width of each region 2 or 3 is taken as the width d1 or d2. The width d1 of the high refractive index region 2 and the width d2 of the low refractive index region 3 are preferably 0.1 μm to 50 μm, more preferably 0.25 μm to 25 μm, and even more preferably 0.5 μm to 10 μm. Film 1 may have other regions, such as a boundary, between the high refractive index region 2 and the low refractive index region 3, and the width of these other regions may be, for example, 0 μm to 50 μm.

[0040] According to this film, when regions with different refractive indices are formed in the plane, the refractive index difference between the regions 2 and 3 with different refractive indices is sufficiently large, so excellent diffraction characteristics can be obtained. As the film 1 obtained using the above-described mixed composition, for example, there are a film obtained by exposing a part of the above-described mixed composition, and a film obtained by exposing a part of the above-described mixed composition to form an exposed part and an unexposed part, and then exposing the unexposed part. Δn is more preferably 0.005 or more, even more preferably 0.007 or more, still more preferably 0.009 or more, and most preferably 0.015 or more, from the viewpoint of the clarity of the boundary between regions with different refractive indices. Δn may be 0.100 or less, 0.080 or less, 0.060 or less, 0.040 or less, or 0.030 or less. Δn can be determined, for example, based on the diffraction efficiency (%) and the following formula (B).

[0041] (In the above formula (B), d is the thickness of the film (nm), λ is the wavelength of the incident light (nm), and θ ０ represents the incident angle of the incident light (°).) The diffraction efficiency is calculated based on the intensity P0 of the incident light, the intensity P1 of the diffracted light emitted, and the following formula (A). Diffraction efficiency (%) = 100 × P1 / P0... (A) When the film of the present invention has an exposed part and an unexposed part, the unexposed part has a higher refractive index than the exposed part because the concentration of the polymer of the photopolymerizable aliphatic monomer is lower in the unexposed part than in the exposed part. Even when the unexposed part is subsequently exposed to become the second exposed part, the second exposed part has a higher refractive index than the exposed part. The above-described exposed part and unexposed part can be formed by a photomask having an aperture or by two-beam interference exposure using a laser beam.

[0042] [Optical component] The optical component of the present invention comprises the above-described film. When regions with different refractive indices (e.g., exposed and unexposed regions) are formed on the surface of the above-described film, the refractive index difference between the regions with different refractive indices can be sufficiently large, and the clarity of the boundary between regions with different refractive indices can be improved, so that excellent diffraction characteristics can be obtained with the optical component of the present invention. The thickness of the above-described film is not particularly limited, but is preferably 1 to 50 μm. From the viewpoint of reducing the weight of the optical component, the thickness of the above-described film is more preferably 1 to 20 μm, and even more preferably 1 to 10 μm. The optical component of the present invention may further comprise a substrate that supports the above-described film. Examples of substrates include transparent substrates (e.g., glass substrates and resin substrates) and opaque substrates (silicon substrates, glass epoxy substrates). When forming an optical component comprising the above-described film, the substrate is preferably a glass substrate from the viewpoint of excellent total reflectivity. The thickness of the substrate is not particularly limited, but is preferably 10 to 8000 μm. When the substrate is a glass substrate or a resin substrate, it is more preferably 100 μm to 1000 μm. The refractive index of the above substrate at 25°C at the wavelength of sodium d-lines is preferably 1.5 or higher from the viewpoint of excellent total reflectivity. The refractive index may also be 1.7 or higher, or 1.9 or higher. Examples of optical components include diffraction gratings and holographic optical elements (HOEs).

[0043] [Image Display Device] The image display device of the present invention has the above-mentioned optical components. In one embodiment, the image display device of the present invention comprises an optical component composed of a diffraction grating and a light guide plate that guides light incident through the optical component. In this case, since excellent diffraction characteristics are obtained by the optical component, leakage of light guided by the light guide plate is suppressed, light is guided efficiently, and the quality of the displayed image can be improved. The image display device of the present invention may further comprise an optical component composed of a diffraction grating that emits light from the light guide plate. Preferably, this diffraction grating is also composed of the optical component of the present invention. In this case, since excellent diffraction characteristics are obtained by the optical component of the present invention, light is efficiently emitted from the light guide plate by the diffraction grating. Therefore, the image display device of the present invention can further improve the quality of the displayed image. The light guide plate is composed of a transparent plate. Examples of transparent plates include glass substrates and resin substrates. In one embodiment, the image display device of the present invention further comprises an image projection unit that projects image light onto the optical component. Examples of image projection units include microprojectors equipped with microdisplays. The microprojector may further include a lens between the microdisplay and the optical component that adjusts the spread of the image light from the microdisplay and directs it into the optical component. More preferably, the image display device is a virtual image display device such as AR glasses of the light guide plate type, a holographic screen, a head-mounted display, or a head-up display. Figure 2 is a schematic diagram showing AR glasses of the light guide plate type, which is one embodiment of the image display device of the present invention. The image display device 100 shown in Figure 2 includes an optical component 10 made of a diffraction grating, a light guide plate 20 that guides the light incident from the optical component 10, an optical component 30 made of a diffraction grating that emits light from the light guide plate 20, and a microprojector as an image projection unit 40 that projects image light onto the optical component 10. As the diffraction grating, for example, the film 1 shown in Figure 1 can be used. The image projection unit 40 includes a microdisplay 41 and a lens 42. The lens 42 is arranged between the microdisplay 41 and the optical component 10. Light propagates through the light guide plate 20 by total internal reflection.When the optical components 10 and 30 are composed of diffraction gratings, they have excellent diffraction characteristics. Therefore, according to the image display device 100, the light propagating through the light guide plate 20 is suppressed from leaking, the backshift of the video is suppressed, and the quality of the video is also improved.

[0044] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0045] The materials used in the examples and comparative examples are as follows. <Polymer> - Resin (a1) (a compound represented by the following structural formula (1A). In the following structural formula (1A), l:m:n = 6.9:64.4:28.7, weight average molecular weight Mw = 8000, refractive index = 1.65)

[0046] - Resin (a2) (a compound represented by the above structural formula (1A). In the following structural formula (1A), l:m:n = 6.9:64.4:28.7, weight average molecular weight Mw = 13510, refractive index = 1.65) - Resin (a3) (a resin having the following constitutional unit, weight average molecular weight Mw = 19900, refractive index = 1.69.)

[0047] - Polymethyl methacrylate (PMMA. Trade name "SUMIPEXX (registered trademark) MGSS", weight average molecular weight Mw = 90000, manufactured by Sumitomo Chemical Co., Ltd.) The above resins (a1), resin (a2) and resin (a3) were synthesized as described in the following Synthesis Examples 1 to 3, respectively. In the description of Synthesis Examples 1 to 3, "parts" means "parts by mass" and "%" means "% by mass".

[0048] (Synthesis Example 1: Preparation of Resin (a1)) In a 1 L flask equipped with a reflux condenser, a dropping funnel and a stirrer, an appropriate amount of nitrogen was flowed to replace the inside of the flask with a nitrogen atmosphere, and 324 parts of propylene glycol monomethyl ether acetate was put in and heated to 85 °C while stirring. Then, 60 parts of acrylic acid, 3,4 - epoxytricyclo [5.2. ２，６ decan - 8 - yl acrylate and 3,4 - epoxytricyclo [5.2.1.0 ２，６A mixed solution of 30 parts of a mixture of decane-9-yl acrylate (trade name "E-DCPA", manufactured by Daicel Corporation), 210 parts of 9-vinylcarbazole, and 190 parts of propylene glycol monomethyl ether acetate was added dropwise over 4 hours. A mixed solution of 31 parts of 2,2-azobis(2,4-dimethylvaleronitrile) dissolved in 155 parts of propylene glycol monomethyl ether acetate was added dropwise over 5 hours. After the addition was complete, the mixture was held at the same temperature for 3 hours and then cooled to room temperature to obtain a copolymer (resin (a1)) solution with a solid content of 31.8%. The weight-average molecular weight Mw of the obtained resin (a1) was 8000.

[0049] (Synthesis Example 2: Preparation of Resin (a2)) A 1 L flask equipped with a reflux condenser, dropping funnel, and stirrer was filled with an appropriate amount of nitrogen to replace the atmosphere inside the flask with a nitrogen atmosphere. 324 parts of propylene glycol monomethyl ether acetate and 13 parts of cyclopentanone were added and heated to 80°C while stirring. Next, a mixed solution of 30 parts of a mixture of 3,4-epoxytricyclo[5.2.1.02,6]decane-8-yl acrylate and 3,4-epoxytricyclo[5.2.1.02,6]decane-9-yl acrylate (content ratio 1:1), 51 parts of acrylic acid, 219 parts of 9-vinylcarbazole, and 188 parts of cyclopentanone was added dropwise over 4 hours. A mixed solution of 32 parts of 2,2-azobis(2,4-dimethylvaleronitrile) dissolved in 143 parts of propylene glycol monomethyl ether acetate was added dropwise over 5 hours. After the dropwise addition was complete, the solution was held at the same temperature for 3 hours, then cooled to room temperature to obtain a copolymer (resin (a2)) solution with a solid content of 31.1%. The weight-average molecular weight Mw of the obtained resin (a2) was 13510.

[0050] (Synthesis Example 3: Preparation of Resin (a3)) A suitable amount of nitrogen was flowed into a 1 L flask equipped with a reflux condenser, dropping funnel and stirrer to replace the atmosphere with nitrogen, and 348 parts of PGMEA were added and heated to 85°C while stirring. Then, a mixed solution of 16 parts acrylic acid, 32 parts of a mixture of 3,4-epoxytricyclo[5.2.1.02,6]decane-8-yl acrylate and 3,4-epoxytricyclo[5.2.1.02,6]decane-9-yl acrylate (mixing ratio 1:1), 269 parts 9-vinylcarbazole, 3.2 parts tert-butyl acrylate, 103 parts by weight of cyclopentanone, and 105 parts of propylene glycol monomethyl ether acetate was added dropwise over 5 hours. A mixed solution of 6 parts 2,2-azobis(2,4-dimethylvaleronitrile) dissolved in 118 parts propylene glycol monomethyl ether acetate was added dropwise over 5 hours. After the addition was complete, the mixture was held at the same temperature for 3 hours and then cooled to room temperature to obtain a copolymer (resin (a3)) solution with a B-type viscosity (23°C) of 85 mPas and a solid content of 31.7%. The weight-average molecular weight Mw of the obtained resin (a3) ​​was 19900.

[0051] <Photopolymerizable Aliphatic Monomers> ・Tripropylene glycol diacrylate (TPGDA, manufactured by Daicel Ornex Corporation. Represented by structural formula (2) below. Refractive index = 1.45, number of photopolymerizable groups per molecule = 2, molecular weight 300) ・Polyethylene glycol 400 diacrylate (PEG400DA. Represented by structural formula (3) below. n ≈ 9. Refractive index = 1.47, number of photopolymerizable groups per molecule = 2, molecular weight 500) ・Trimethylolpropane ethoxytriacrylate (EBECRYL 160S, manufactured by Daicel Ornex Corporation. Represented by structural formula (4) below. x + y + z ≈ 3. Refractive index = 1.50, number of photopolymerizable groups per molecule = 3, molecular weight 428) • Trifunctional (alkoxylated) trimethylolpropane acrylate (A-GLY-9E, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.). Represented by the following structural formula (5). l + m + n ≈ 9, Z is -CH ２ CH ２Shows O-. Refractive index = 1.47, number of photopolymerizable groups per molecule = 3, molecular weight 650) ・A mixture of dipentaerythritol pentaacrylate (DPPA. Dipentaerythritol pentaacrylate is represented by the following structural formula (6B)) and dipentaerythritol hexaacrylate (DPHA. Dipentaerythritol hexaacrylate is represented by the following structural formula (6A)) (Refractive index = 1.49, number of photopolymerizable groups per molecule = 5 or 6, molecular weight 520) ・Fluorene-based acrylate (EA-0300, manufactured by Osaka Gas Chemical Co., Ltd. Represented by the following structural formula (7). Refractive index = 1.56, number of photopolymerizable groups per molecule = 2, molecular weight 898) EO-modified bisphenol A diacrylate (EBECRYL150, manufactured by Daicel Ornex Co., Ltd. n+m=4. Represented by the following structural formula (8). Refractive index = 1.53, number of photopolymerizable groups per molecule = 2, molecular weight 512)

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] <Photopolymerization Initiator> ・NCI-730 (Manufactured by ADEKA Corporation, an oxime ester-based photopolymerization initiator.)

[0060] <Solvent> ・PGMEA (Polypropylene glycol monomethyl ether acetate)

[0061] <Example 1> A mixed composition was obtained by mixing a resin (a1) as a polymer, TPGDA, a photopolymerizable aliphatic monomer, a photopolymerization initiator, and a solvent. At this time, the blending ratio of the photopolymerizable aliphatic monomer was 233 parts by mass, the blending ratio of the photopolymerizable aliphatic monomer was 3.33 parts by mass, and the blending ratio of the solvent was 1000 parts by mass per 100 parts by mass of polymer.

[0062] <Examples 2-10 and Comparative Examples 1-3> Mixed compositions were obtained in the same manner as in Example 1, except that the type of polymer, the type of photopolymerizable monomer, and the blending ratio of the photopolymerizable monomer to the polymer were as shown in Table 1 or Table 2.

[0063] <Evaluation> (Preparation of evaluation sample) A glass substrate (refractive index = 1.51) with a thickness of 0.5 mm and surface dimensions of 50 mm x 50 mm was spin-coated with the mixed compositions of the examples and comparative examples at 1000 rpm for 0.5 minutes, and then dried at 80°C for 3 minutes to obtain an unexposed film with a thickness of 2000 nm. A photomask was then placed on the unexposed film, and exposure was performed through the photomask to form a film (thickness d = 2000 nm) in which exposed and unexposed areas were alternately formed in a certain direction. At this time, a photomask was used which had 500 slits with a width of 10 μm and a length of 50 mm, with a distance of 10 μm between adjacent slits. In this way, an evaluation sample consisting of a glass substrate and a film was obtained.

[0064] (1) Refractive index difference (Δn) For the evaluation sample obtained as described above, an automated absolute reflectance measurement system (manufactured by JASCO Corporation) was used to measure the incident angle θ that maximizes diffraction efficiency on the surface of a film with thickness d (nm). ０ Light with a wavelength of λ = 589 nm was incident on the sample, and the intensity P1 of the emitted diffracted light was measured. The intensity P0 of the incident light was measured by directly measuring the intensity of the light after removing the sample. Then, the diffraction efficiency was calculated based on the intensity P1 of the diffracted light, the intensity P0 of the incident light, and the following formula (A). Diffraction efficiency (%) = 100 × P1 / P0 ... (A) Meanwhile, the refractive index difference Δn was calculated based on the diffraction efficiency calculated as described above and the following formula (B). The results are shown in Tables 1 and 2.

[0065]

[0066] (2) Clarity of the boundary between the exposed and unexposed areas Next, differential interference contrast observation (magnification: 20x) was performed on the unexposed area and the vicinity of the boundary between the exposed and unexposed areas using a differential interference microscope under reflected light illumination to check whether a boundary could be observed between the unexposed and exposed areas. The clarity of the boundary between areas with different refractive indices (exposed and unexposed areas) was then evaluated based on the following criteria. The results are shown in Tables 1 and 2. (Criteria) A...The boundary between the exposed and unexposed areas can be observed clearly and without interruption B...The boundary between the exposed and unexposed areas can be observed without interruption C...The boundary between the exposed and unexposed areas can be observed with some interruption D...The boundary between the exposed and unexposed areas cannot be observed

[0067]

[0068]

[0069] As shown in Tables 1 and 2, the refractive index difference Δn was 0.002 or greater in Examples 1 to 10, while it was 0.000 in Comparative Examples 1 to 4. Furthermore, the evaluation results for the clarity of the boundary between regions with different refractive indices (exposed and unexposed areas) were "A," "B," or "C" in Examples 1 to 10, while it was "D" in Comparative Examples 1 to 3. Therefore, it was confirmed that the mixed composition of the present invention can increase the refractive index difference between regions with different refractive indices when forming a film having regions with different refractive indices within the plane, and can improve the clarity of the boundary between regions with different refractive indices (exposed and unexposed areas).

[0070] 1...Film, 2...Region with high refractive index, 3...Region with low refractive index, d1...Width of region 2, d2...Width of region 3, 10, 30...Optical components, 20...Light guide plate, 40...Image projection unit, 100...Image display device.

Claims

A photopolymerizable aliphatic monomer having a refractive index of less than 1.50 at the wavelength of the sodium D line at 25°C, A mixed composition comprising a polymer having a refractive index of 1.60 or higher at the wavelength of sodium D lines at 25°C. 　 The mixed composition according to claim 1, wherein the photopolymerizable aliphatic monomer is blended in a ratio of 40 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the polymer. 　 The mixed composition according to claim 1, wherein the number of photopolymerizable groups per molecule of the photopolymerizable aliphatic monomer is 4 or less. 　 The mixed composition according to claim 1, wherein the molecular weight of the photopolymerizable aliphatic monomer is 600 or less. The mixed composition according to claim 1, wherein the polymer has a ring structure in its side chain that has aromaticity according to Hückel's rule and has 4N+2 π electrons (where N is an integer of 1 or more). 　 The mixed composition according to claim 1, wherein the polymer has at least one ring structure in its side chain, selected from the group consisting of heterocyclic rings and aromatic rings bonded to heteroatoms. 　 The mixed composition according to claim 1, wherein the weight-average molecular weight of the polymer is 25,000 or less. 　 A film comprising the mixed composition according to any one of claims 1 to 7. 　 A film obtained using the mixed composition according to any one of claims 1 to 7, Having two or more regions with different refractive indices within the plane, A film in which the refractive index difference between the aforementioned regions is 0.001 or greater. 　 An optical component comprising the film described in claim 8. 　 An image display device comprising the optical component described in claim 10.

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