Red-light photoinitiating system, holographic recording medium and holographic optical element

Abstract

Disclosed in the present application are a red-light photoinitiating system, a photopolymer-type holographic recording medium, a holographic optical element and a display device. The red-light photoinitiating system comprises a red-light photosensitive dye and a co-initiator. By means of the red-light photoinitiating system, monomer polymerization can be efficiently initiated, and the dye can be quickly photobleached under irradiation at a corresponding wavelength. Furthermore, the material cost is low, and the holographic recording performance of a photopolymer is effectively improved.

Description

Red-light photosensitive induction system, holographic recording medium and holographic optical elements

[0001] This application claims priority to Chinese Patent Application No. 2024117490266, filed on November 29, 2024, entitled "Red Light Photosensitive Initiation System, Holographic Recording Medium and Holographic Optical Element", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of holographic optics technology, and in particular to a red light photosensitive initiation system, a photopolymer holographic recording medium, holographic optical elements, and display devices. Background Technology

[0003] To provide a realistic visual experience, rich information presentation, better interactivity, and a wide range of applications, augmented reality (AR) glasses need to achieve color display. This requires the volume holographic grating (VHG) to be sensitive to red, green, and blue light. Therefore, photopolymerization needs to be able to rapidly initiate monomer polymerization under laser irradiation of the corresponding light source wavelength. However, currently, red light-sensitive systems generally have low initiation efficiency. Summary of the Invention

[0004] Based on this, this application provides a red light photosensitive initiation system, a holographic recording medium, a holographic optical element, and a display device.

[0005] In a first aspect, this application provides a red light photosensitive initiation system, the red light photosensitive initiation system comprising a red light photosensitive dye and a co-initiator, wherein the red light photosensitive dye is selected from one of the following general structural formulas:

[0006] Wherein, R1 and R2 each independently represent one of the following structural formulas:

[0007] Among them, R3, R4, and R5 each independently represent hydrogen and C1-C. 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Any one of alkylamino and phenyl;

[0008] R6, R7, and R8 each independently represent hydrogen. Nitro, halogen, phenyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Alkylamino, Any one of them; R9 represents hydrogen, C1-C 20 Any one of the alkyl groups.

[0009] Secondly, this application provides a photopolymer-type holographic recording medium, which includes: a film-forming resin, a writing monomer, a red light photosensitive initiation system, a chain transfer agent, a catalyst, and additives. The film-forming resin includes compounds having multiple isocyanate reactive functional groups and polyisocyanate group compounds. The red light photosensitive initiation system is the red light photosensitive initiation system described above.

[0010] Thirdly, this application provides a holographic optical element, the raw material of which includes the photopolymer type holographic recording medium as described above.

[0011] Fourthly, this application provides a display device, which includes the holographic optical element described above.

[0012] The red light photosensitive initiation system of this application embodiment can efficiently initiate monomer polymerization under irradiation with a 600-800nm ​​light source, and the dye can be rapidly photobleached under irradiation with the corresponding wavelength, resulting in low material cost. This photopolymer holographic recording material, using isocyanate-alcohol as the film-forming resin, employs this red light photosensitive initiation system. This photopolymer holographic recording material can be used to fabricate holographic optical elements (HOEs), exhibiting high photosensitivity and a recording grating with high diffraction efficiency. Attached Figure Description

[0013] Figure 1 shows the carbon-carbon double bond conversion curves for samples 1, 9, 17, and 24.

[0014] Figure 2 shows the carbon-carbon double bond conversion curves for samples 26, 29, and 35;

[0015] Figure 3 shows the diffraction efficiency growth curves of the photopolymer sample recording transmission and reflection holographic gratings as shown in Table 3.

[0016] Figure 4 shows the photopolymer samples shown in Table 3 under 633nm laser (50mW / cm²) conditions. 2 Photobleaching curve under irradiation;

[0017] Figure 5 shows the diffraction efficiency growth curves of the comparative photopolymer samples recorded by the transmission and reflection holographic gratings, as shown in Table 8. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0020] Augmented reality (AR) glasses are gradually changing the way we perceive and interact with the world. Wearing AR glasses, users can enter a completely new world where virtual and reality intertwine anytime, anywhere, bringing them an unprecedented immersive experience.

[0021] Augmented Reality (AR) glasses based on holographic waveguides can provide high-resolution, high-quality imaging, bringing users a clearer and more realistic AR experience. The core optical component of the holographic waveguide system is the input / output coupling grating. Volume holographic gratings (VHGs) made of photopolymers have the advantages of small size and light weight, which is beneficial for the thinner and lighter design of AR glasses.

[0022] To provide a realistic visual experience, rich information presentation, better interactivity, and a wide range of applications, AR glasses need to achieve color display. This requires VHG to be sensitive to red, green, and blue light. Therefore, photopolymers need to be able to rapidly initiate monomer polymerization under laser irradiation of the corresponding wavelength. However, currently, red light-sensitive systems generally have low initiation efficiency.

[0023] To address the aforementioned challenges, this application provides a red-light photoinitiating system, a holographic recording medium, and a holographic optical element. This red-light photoinitiating system can efficiently initiate monomer polymerization under 600-800 nm light source irradiation, and the dye can be rapidly photobleached under the corresponding wavelength irradiation, resulting in low material cost. This photopolymer holographic recording material, using isocyanate-alcohol as the film-forming resin, employs this red-light photoinitiating system. This photopolymer holographic recording material can be used to fabricate holographic optical elements (HOEs), exhibiting high photosensitivity and a recording grating with high diffraction efficiency.

[0024] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0025] This application provides a red light photosensitive initiation system, which includes a red light photosensitive dye and a co-initiator. The red light photosensitive dye is selected from one of the following general structural formulas:

[0026] Wherein, R1 and R2 each independently represent one of the following structural formulas:

[0027] Among them, R3, R4, and R5 each independently represent hydrogen and C1-C. 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Any one of alkylamino and phenyl;

[0028] R6, R7, and R8 each independently represent hydrogen. Nitro, halogen, phenyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Alkylamino, Any one of them; R9 represents hydrogen, C1-C 20 Any one of the alkyl groups.

[0029] It should be noted that in the dyes expressed by the above-mentioned general structural formulas of Dye-1, the cations exist in a delocalized manner, and multiple tautomer structures exist. In the embodiments of this application, when at least one tautomer structure of certain dyes is applicable to the general structural formulas, a certain dye is set as a dye represented by the general structural formulas. In the embodiments of this application, for dyes represented by general structural formulas, any tautomer structure can be used as long as at least one of its tautomer structures is applicable to the general structural formula. For example, the following dyes have three expression forms i, ii, and iii, all of which represent the same dye. In the embodiments of this application, any one of the expression forms i, ii, and iii can be exemplarily shown to represent the type of dye contained in the red light photosensitive initiation system protected in the embodiments of this application.

[0030] In some embodiments, R3, R4, and R5 each independently represent hydrogen, C1-C 10 Alkyl, C1-C 10 Alkoxy, C1-C 10 Any one of alkylamino and phenyl.

[0031] In some embodiments, R6, R7, and R8 each independently represent hydrogen, Nitro, halogen, phenyl, C1-C 10 Alkyl, C1-C 10Alkoxy, C1-C 10 Alkylamino, Any one of them.

[0032] In some embodiments, R9 represents hydrogen, C1-C 10 Any one of the alkyl groups.

[0033] In some embodiments, the red light-sensitive dye Dye-1 is selected from one of the following structures:

[0034] In some embodiments, the red light-sensitive dye Dye-2 is selected from one of the following structures:

[0035] In some embodiments, the co-initiator includes amine co-initiators. When used in conjunction with red-light-sensitive dyes, the co-initiator can enhance the photoinitiation effect of the red-light-sensitive initiation system. Amine co-initiators include, but are not limited to, N-phenylglycine and L-arginine.

[0036] It should be noted that the addition of other organic compounds, inorganic compounds, or organic-inorganic hybrids, in addition to the red light photosensitive dye and co-initiator, does not affect the function of the red light photosensitive initiation system and therefore does not deviate from the scope of protection of this application.

[0037] This application provides a photopolymer-type holographic recording medium, which includes: a film-forming resin, a writing monomer, a red light photosensitive initiation system, a chain transfer agent, a catalyst, and additives. The film-forming resin includes compounds having multiple isocyanate reactive functional groups and polyisocyanate group compounds. The red light photosensitive initiation system is any of the red light photosensitive initiation systems described above.

[0038] In some embodiments, the content of the film-forming resin, by weight percentage, is 30%-60%, for example: 30%, 35%, 40%, 42.5%, 45%, 47.5%, 50%, 55%, 60%, etc., wherein the content of compounds having multiple isocyanate reactive functional groups (e.g., polyfunctional hydroxyl compounds, polyfunctional thiol compounds) and polyisocyanate group compounds can be determined based on the content of multiple isocyanate reactive functional groups (e.g., hydroxyl, thiol) in the compounds having multiple isocyanate reactive functional groups and the isocyanate content in the polyisocyanate group compounds; the content of the writing monomer is 40%-50%, for example: 30%, 35%, 40 ... The red light photosensitive initiation system has a content of 0.01%-8%, such as 0.01%, 0.05%, 1%, 3%, 5%, 6%, 7%, 8%, etc.; the chain transfer agent has a content of 0.05%-5%, such as 0.05%, 1%, 2%, 3%, 4%, 5%, etc.; the catalyst has a content of 0.001%-3%, such as 0.001%, 0.005%, 0.01%, 0.05%, 1%, 2%, 3%, etc.; and the additive has a content of 0.1%-10%, such as 0.1%, 0.5%, 1%, 3%, 5%, 7%, 9%, 10%, etc.

[0039] In some embodiments, in the red light photoinitiating system, the mass ratio of the co-initiator to the red light photosensitive dye is 0.1-10:0.0001-5.

[0040] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.001-5.

[0041] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.01-5.

[0042] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.1-5.

[0043] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.0001-0.001.

[0044] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.0001-0.01.

[0045] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.0001-0.1.

[0046] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.0001-1.

[0047] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.001-0.01.

[0048] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.001-0.1.

[0049] For example, the mass ratio of the co-initiator to the red light-sensitive dye can be 0.1-10:0.001-1.

[0050] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.01-0.1.

[0051] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.01-1.

[0052] For example, the mass ratio of the co-initiator to the red light photosensitive dye can be 0.1-10:0.1-1.

[0053] In some embodiments, the additives include one or more of defoamers, leveling agents, plasticizers, dehydrating agents, ultraviolet absorbers, light stabilizers, and antioxidants.

[0054] In some embodiments, when the additive includes a defoamer, the content of the defoamer does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

[0055] In some embodiments, when the additive includes a leveling agent, the leveling agent content does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

[0056] In some embodiments, when the additive includes a plasticizer, the content of the plasticizer does not exceed 3% based on the total mass of the photopolymer-type holographic recording medium.

[0057] In some embodiments, when the additive includes an ultraviolet absorber, the content of the ultraviolet absorber does not exceed 3% based on the total mass of the photopolymer-type holographic recording medium.

[0058] In some embodiments, when the additive includes an antioxidant, the content of the antioxidant does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

[0059] In some embodiments, when the additive includes a light stabilizer, the content of the light stabilizer does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

[0060] In some embodiments, in the compound having a plurality of isocyanate reactive functional groups, the isocyanate reactive functional groups are hydroxyl and mercapto groups.

[0061] In some embodiments, the compound having a plurality of isocyanate reactive functional groups is a low refractive index compound having two or more hydroxyl or mercapto functional groups.

[0062] In some embodiments, the low-refractive-index compound having two or more hydroxyl or mercapto functional groups is: 2-ethyl-1,3-hexanediol, 1,2,4-butanetriol, 1,6-hexanediol, 2,5-hexanediol, 1,4-cyclohexanediol, 1,8-octanediol, 1,7-heptanediol, 1,3-butanediol, 1,5-pentanediol, 1,4-cyclohexanediol, 1,3-cyclopentanediol, tetraethylene glycol, trihydroxymethyl Ethane, trimethylolpropane, glycerol, triethanolamine, polyester polyols with a molecular weight of 100-2000, polycarbonate polyols, polyether polyols, 2,3-dithio(2-mercapto)-1-propanethiol, 1,2-octanedithiol, 2,5-dimethylmercapto-1,4-dithiane, 1,2-butanedithiol, 1,3-butanedithiol, 3,7-dithia-1,9-nonanedithiol, 2,3-butanedithiol.

[0063] In some embodiments, the polyisocyanate compound is a low-refractive-index compound having two or more isocyanate groups.

[0064] In some embodiments, the polyisocyanate group compound is: trimethylhexamethylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tri(hexamethylene)isocyanate, or dicyclohexylmethane diisocyanate.

[0065] In some embodiments, the writing monomer comprises a polymerizable monomer / oligomer.

[0066] In some embodiments, the polymerizable monomer is selected from at least one of alkenylnaphthalene compounds, alkenylanthracene compounds, alkenylbenzene compounds, acrylic acid compounds, methacrylic acid compounds, acrylate compounds, methacrylate compounds, N-vinylpyrrole, N-vinylcarbazole, N-vinylimidazol, N-vinylindole, N-vinylpyrrolidone, and trans-N-3-yntynebutenylcarbazole.

[0067] For example, the alkenylbenzene compound may be selected from styrene, 1,1-stilbene, 4-cyanostrene, 4-methylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2-bromostyrene, 3-bromostyrene, 4-bromostyrene, 4-nitrostyrene, 4-vinylaniline, N-4-vinylphenyl-N,N-dimethylamine, p-(chloromethyl)styrene, p-(bromomethyl)styrene, allyl phenoxyacetate, allyl phenyl carbonate, etc.

[0068] Exemplarily, the acrylic compound can be acrylic acid and its derivatives; exemplarily, the acrylate compound can be selected from 2-naphthyl acrylate, 2-phenoxyethyl acrylate, phenoxyethyl acrylate, epoxy acrylate, pentachlorophenyl acrylate, pentabromophenyl acrylate, 2-naphthyl acrylate, 1,4-bis(2-thionaphthyl)2-butyl acrylate, phenoxyethoxyethyl acrylate, bisphenol A diacrylate, tetrabromobisphenol A diacrylate, 2-naphthyl acrylate, 2,4,6-tribromophenyl acrylate, o-phenylphenoxyethyl acrylate, furan-2-yl acrylate, N-hydroxysuccinimide acrylate, benzyl acrylate, 4-biphenylmethanol acrylate, 3-phenoxybenzyl acrylate, quinoline-8-yl acrylate, p-chlorophenyl acrylate, p-bromophenyl acrylate, 2-phenylethyl acrylate, 2,4,6-trichlorophenyl acrylate, pentabromobenzyl acrylate, etc.

[0069] For example, the methacrylate compound may be selected from 2-naphthylmethacrylate, 2-phenoxyethylmethacrylate, pentachlorophenylmethacrylate, pentabromophenylmethacrylate, 1,4-di(2-thionaphthyl)-2-butyl methacrylate, phenoxyethoxyethyl methacrylate, bisphenol A dimethacrylate, tetrabromobisphenol A dimethacrylate, 2,4,6-tribromophenylmethacrylate, o-phenylphenoxyethyl methacrylate, N-hydroxysuccinimide methacrylate, benzyl methacrylate, and 4-biphenylmethanol. 3-Phenoxybenzyl methacrylate, quinoline-8-yl methacrylate, p-bromophenyl methacrylate, 2-phenylethyl methacrylate, 2,4,6-trichlorobenzyl methacrylate, pentabromobenzyl methacrylate, phenyl methacrylate, 9-anthrayl methyl methacrylate, bisphenol A glycerol dimethacrylate, 1-naphthyl methacrylate, hydroquinone monomethacrylate, 2,4,6-trichlorophenyl methacrylate, pentabromophenyl methacrylate, pentachlorophenyl methacrylate, phenoxyethyl methacrylate, etc.

[0070] For example, the alkenyl anthracene compound may be selected from 2-vinylanthracene, 9,10-divinylanthracene, 9-vinylanthracene, etc.

[0071] For example, the alkenyl naphthalene compound may be selected from 1-vinylnaphthalene, 2-vinylnaphthalene, 1-styrene naphthalene, etc.

[0072] Furthermore, the chain transfer agent includes, but is not limited to, one or more of the following: dodecyl mercaptoethanol, isooctyl 3-mercaptopropionate, hexamethylene mercaptoethanol, phenylethyl mercaptoethanol, mercaptopropionic acid, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 2,4-diphenyl-4-methyl-1-pentene, 4-methyl-4H-1,2,4-triazole-3-thiol, sodium hypophosphite, carbon tetrachloride, and carbon tetrabromide.

[0073] Furthermore, the catalyst is a tertiary amine catalyst and an organometallic catalyst, including but not limited to triethylenediamine, bis(dimethylaminoethyl) ether, dimethylethanolamine, 2-(2-dimethylamino-ethoxy)ethanol, trimethylhydroxyethylpropanediamine, N,N-bis(dimethylaminopropyl)isopropanolamine, dibutyltin dilaurate, stannous octoate, potassium carboxylate catalysts, and bismuth carboxylate catalysts.

[0074] Furthermore, the defoamer is an organosilicone defoamer, such as BYK-011, BYK-012, BYK-014, BYK-023, BYK-051N, BYK-085, BYK-1610, BYK-1707, BYK-1740, BYK-1760 manufactured by BYK Corporation, DC65 and AFE-7820 manufactured by Dow Corning Incorporated, or any mixture of these defoamers in any proportion.

[0075] Furthermore, the leveling agent is an organosilicon surface additive, such as BYK-302, BYK-306, BYK-307, BYK-327, BYK-329, BYK-333, BYK-356, BYK-358, BYK-378, BYK-3455, BYK-3566, or any mixture of these surface additives manufactured by BYK Corporation.

[0076] Furthermore, the plasticizer is toluene, xylene, dimethylformamide, dimethylacetamide, glycerol, phthalate, or any mixture of these compounds in any proportion.

[0077] Furthermore, the dehydrating agents include, but are not limited to, p-toluenesulfonyl isocyanate, triethyl orthoformate, CUWR-WB20 dehydrating agent from Guangzhou Yourun Synthetic Materials Co., Ltd., ALT-201 dehydrating agent from Anxiang Elite Chemical Co., Ltd., and PCCI dehydrating agent from Shanghai Luer Chemical Trading Co., Ltd.

[0078] Furthermore, the ultraviolet absorber includes, but is not limited to, 2-hydroxy-4-n-octyloxybenzophenone, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-ethylenediamide, 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-dipentylphenol, 2-(2H-benzotriazol-2)-4,6-di(1-methyl-1-phenylethyl)phenol, or any mixture of these additives in any proportion.

[0079] Furthermore, the light stabilizer includes, but is not limited to, light stabilizer 944, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, light stabilizer 622, or any mixture of these additives in any proportion.

[0080] Furthermore, the antioxidants include, but are not limited to, Irganox 1010, Irganox 168, Irganox 1076, Irganox 1098, Irganox MD1024, Irganox 1035, BASF Liquid Antioxidant 1135, Irganox B225, Irganox PS800 (DLTP), Irganox B900, Irganox 3114, Irganox 245, Irganox B215, Irganox PS-802FL, Irganox Borchors Ascinin@Special, Irganox Borchors Ascinin@P, or any mixture of these additives in any proportion.

[0081] This application provides a holographic optical element, the raw material of which includes the photopolymer-type holographic recording medium as described above. The holographic optical element includes, but is not limited to, a volume holographic grating.

[0082] This application provides a display device, which includes the holographic optical element described above.

[0083] The embodiments of this application will be described below through specific examples.

[0084] Example 1

[0085] Add 1 wt% co-initiator (N-phenylglycine added to samples 1-12, and L-arginine added to samples 13-25) and 0.01 wt% dye to methyl methacrylate (MMA). The dye is selected from any one of the dyes listed in Table 1 below. Stir to thoroughly mix the three components into a homogeneous prepolymer solution, pour into a 0.1 mm thick hollow glass mold, and use a real-time infrared spectroscopy instrument to test the prepolymer solution at a light source of 600-800 nm (50 mW / cm²). 2 Photopolymerization kinetics curves under irradiation. Some photopolymerization kinetic curves are shown in Figure 1. It was found that different visible light initiation systems can efficiently initiate the polymerization of monomer MMA under irradiation. Relevant data are summarized in Table 1. Under low exposure intensity, a carbon-carbon double bond conversion rate of over 90% can be achieved in just 100 seconds, demonstrating fast reaction speed and high monomer conversion rate.

[0086] Table 1

[0087] Example 2

[0088] Different monomers were selected (see Table 2), and 1 wt% N-phenylglycine and 0.01 wt% dye (see Table 2) were added. The mixture was stirred to ensure thorough mixing of the three components into a homogeneous prepolymer solution. This solution was then poured into a hollow glass mold with a thickness of 0.1 mm. The prepolymer solution was tested using a real-time infrared spectrometer at different wavelengths of light source (50 mW / cm²). 2 The photopolymerization kinetics curves under irradiation are shown in Figure 2. It was found that the visible light initiation system has a high efficiency initiation effect on different monomers under irradiation.

[0089] Table 2

[0090] Examples 3 to 7

[0091] Examples 3 to 7 provide five photopolymer-type holographic recording media, the raw material components of which are detailed in Tables 3-7.

[0092] The preparation of photopolymer-based holographic recording media includes the following steps:

[0093] In a darkroom, the raw material components listed in Table 3 are added sequentially to a 500mL container equipped with a stirrer. The mixture is stirred thoroughly at room temperature for 15 minutes. Dust and other impurities are removed by passing the mixture through a 0.45-micron filter to obtain a mixed solution. The mixed solution is then coated to prepare a photopolymer with a thickness of 15μm. After curing at room temperature, a holographic recording medium can be obtained.

[0094] Photopolymer-type holographic recording media containing the raw material components listed in Tables 4-7 were prepared using the same preparation method described above.

[0095] Example 3 uses a 633nm laser for holographic recording, with a recording light intensity of 4mW / cm². 2 Figure 3 shows the diffraction efficiency growth curves of the photopolymer sample for transmission (3000 lines / mm) and reflection (4500 lines / mm) gratings. The sample was subjected to a 633nm laser (50mW / cm²)... 2 The photobleaching curve under irradiation is shown in Figure 4.

[0096] Example 4 uses a 760nm laser for holographic recording, with a recording light intensity of 5mW / cm². 2 The diffraction efficiency of transmission (2900 lines / mm) and reflection (4300 lines / mm) gratings was recorded on photopolymer samples.

[0097] Example 5 uses a 640nm laser for holographic recording, with a recording light intensity of 4.5mW / cm². 2 The diffraction efficiency of transmission (3000 lines / mm) and reflection (4400 lines / mm) gratings was recorded on photopolymer samples.

[0098] Example 6 uses a 630nm laser for holographic recording, with a recording light intensity of 6mW / cm². 2 The diffraction efficiency of transmission (2800 lines / mm) and reflection (4100 lines / mm) gratings was recorded on photopolymer samples.

[0099] Example 7 uses a 630nm laser for holographic recording, with a recording light intensity of 4.8mW / cm². 2 The diffraction efficiency of transmission (2900 lines / mm) and reflection (4200 lines / mm) gratings was recorded on photopolymer samples.

[0100] The formula for calculating the photosensitivity of photopolymer samples is:

[0101] In the formula, η is the maximum diffraction efficiency of the recording grating (%), d is the sample thickness (cm), and I is the exposure light intensity (mW / cm). 2 t is the exposure time required to reach maximum diffraction efficiency in seconds, and S is the sensitivity in cm / mJ.

[0102] Table 3

[0103] Table 4

[0104] Table 5

[0105] Table 6

[0106] Table 7

[0107] Comparative Examples 1 to 5

[0108] The methods for preparing photopolymer-type holographic recording media in Comparative Examples 1 to 5 were the same as those in Examples 3 to 7, except that the raw materials for the photopolymer-type holographic recording media in Comparative Examples 1 to 5 were shown in Tables 8-12. After obtaining the holographic recording media, holographic recording was performed using a 633nm laser with a recording intensity of 4mW / cm². 2 Figure 5 shows the diffraction efficiency growth curves for recording transmission (3000 lines / mm) and reflection (4500 lines / mm) gratings on photopolymer samples. The photopolymer samples exhibit low photosensitivity (transmission <4.9 cm / mJ, reflection <3.7 cm / mJ), resulting in low diffraction efficiency for recording transmission / reflection volume holographic gratings.

[0109] Table 8

[0110] Table 9

[0111] Table 10

[0112] Table 11

[0113] Table 12

[0114] Experimental example:

[0115] The performance of the holographic recording media of Examples 3 to 7 and Comparative Examples 1 to 5 were tested, and the results are shown in Figures 3-5 and Table 13.

[0116] The testing method includes the following steps:

[0117] Solid-state lasers with wavelengths of 405 nm, 532 nm, and 633 nm were used as light sources. After passing through a beam expander, beam splitter, and half-wave plate, two beams with the same intensity and a diameter of 8 mm were obtained. The two beams were intersected and exposed within the prepared holographic recording medium, with a light intensity of 2.91 mW / cm². 2The detection light source is a 785nm wavelength solid-state laser that does not react with the recording medium. The detection light is incident on the exposure area from the Bragg angle. The transmitted light and diffracted light are monitored in real time by a photodetector. The single grating diffraction efficiency (η) of the photopolymer sample and the photosensitivity (S) of the recording medium are calculated by formulas (1) to (3).

[0118] In the formula, η is the diffraction efficiency, η max For the highest diffraction efficiency, I d For diffracted light, I t S represents transmitted light, S represents photosensitivity, E represents exposure energy, and ΔE represents the exposure energy required to achieve the highest diffraction efficiency.

[0119] Table 13

[0120] As can be seen from Figures 3-5 and Table 13, the exposure amount of the holographic recording medium in Embodiments 3-7 of this application is less than that of the comparative example, the diffraction efficiency of the holographic recording medium in Embodiments 3-7 of this application is greater than that of the comparative example, and the sensitivity of the holographic recording medium in Embodiments 3 and 7 of this application is greater than that of the comparative example.

[0121] In the embodiments of this application, a red-light photosensitive initiation system composed of squaricocyanine dyes and co-initiators can rapidly generate initiating free radicals under irradiation by LEDs, lasers, or other light sources at 600-800 nm, initiating monomer polymerization. At low exposure intensities, monomers or resins with this red-light photosensitive initiation system can achieve a monomer conversion rate of over 90%, exhibiting characteristics of fast reaction speed and high monomer conversion rate. When the red-light photosensitive initiation system of this application is used to prepare photopolymer-type holographic recording media, the photopolymer sample exhibits high photosensitivity and can record high diffraction efficiency (>90%) transmission / reflection volume holographic gratings.

[0122] It should be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application.

[0123] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0124] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A red light-sensitive initiation system, the red light-sensitive initiation system comprising a red light-sensitive dye and a co-initiator, wherein the red light-sensitive dye is selected from one of the following general structural formulas: in, R1 and R2 each independently represent one of the following structural formulas: Among them, R3, R4, and R5 each independently represent hydrogen and C1-C. 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Any one of alkylamino and phenyl; R6, R7, and R8 each independently represent hydrogen. Nitro, halogen, phenyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Alkylamino, Any one of them; R9 represents hydrogen and C1-C 20 Any one of the alkyl groups.

2. The red light photosensitive initiation system according to claim 1, wherein, R3, R4, and R5 each independently represent hydrogen and C1-C. 10 Alkyl, C1-C 10 Alkoxy, C1-C 10 Any one of alkylamino and phenyl.

3. The red light photosensitive initiation system according to claim 1, wherein, R6, R7, and R8 each independently represent hydrogen. Nitro, halogen, phenyl, C1-C 10 Alkyl, C1-C 10 Alkoxy, C1-C 10 Alkylamino, Any one of them.

4. The red light photosensitive initiation system according to claim 3, wherein, R9 represents hydrogen and C1-C. 10 Any one of the alkyl groups.

5. The red light photosensitive initiation system according to claim 1, wherein, The red light-sensitive dye Dye-1 is selected from one of the following structures:

6. The red light photosensitive initiation system according to claim 1, wherein, The red light-sensitive dye Dye-2 is selected from one of the following structures:

7. The red light photosensitive initiation system according to claim 1, wherein, The co-initiators include amine co-initiators.

8. The red light photosensitive initiation system according to claim 7, wherein, The amine co-initiator includes at least one of N-phenylglycine and L-arginine.

9. The red light photosensitive initiation system according to claim 1, wherein, The mass ratio of the co-initiator to the red light photosensitive dye is 0.1-10:0.0001-5.

10. A photopolymer-type holographic recording medium, the photopolymer-type holographic recording medium comprising: The film-forming resin, writing monomer, red light photosensitive initiation system, chain transfer agent, catalyst, and additives, wherein the film-forming resin includes compounds having multiple isocyanate reactive functional groups and polyisocyanate group compounds, and the red light photosensitive initiation system is the red light photosensitive initiation system according to any one of claims 1-9.

11. The photopolymer-type holographic recording medium according to claim 10, wherein, The film-forming resin comprises 30%-60% by mass percentage; the writing monomer comprises 30%-60% by mass percentage; the red light photosensitive initiation system comprises 0.01%-8% by mass percentage; the chain transfer agent comprises 0.05%-5% by mass percentage; the catalyst comprises 0.001%-3% by mass percentage; and the additive comprises 0.1%-10% by mass percentage.

12. The photopolymer-type holographic recording medium according to claim 10, wherein, The additives include one or more of the following: defoamers, leveling agents, plasticizers, dehydrating agents, ultraviolet absorbers, light stabilizers, and antioxidants.

13. The photopolymer-type holographic recording medium according to claim 12, wherein, When the additive includes an antifoaming agent, the content of the antifoaming agent shall not exceed 3% based on the total mass of the photopolymer holographic recording medium; And / or, when the additive includes a leveling agent, the leveling agent content does not exceed 3% based on the total mass of the photopolymer holographic recording medium; And / or, when the additive includes a plasticizer, the content of the plasticizer shall not exceed 3% based on the total mass of the photopolymer-type holographic recording medium; And / or, when the additive includes an ultraviolet absorber, the content of the ultraviolet absorber shall not exceed 3% based on the total mass of the photopolymer-type holographic recording medium; And / or, when the additive includes an antioxidant, the content of the antioxidant shall not exceed 3% based on the total mass of the photopolymer holographic recording medium; And / or, when the additive includes a light stabilizer, the content of the light stabilizer does not exceed 3% based on the total mass of the photopolymer holographic recording medium.

14. The photopolymer-type holographic recording medium according to claim 10, wherein, In the compound having multiple isocyanate reactive functional groups, the isocyanate reactive functional groups include at least one of hydroxyl and mercapto groups.

15. The photopolymer-type holographic recording medium according to claim 10, wherein, The writing monomer includes polymerizable monomers.

16. The photopolymer-type holographic recording medium according to claim 15, wherein, The polymerizable monomer is selected from at least one of alkenylnaphthalene compounds, alkenylanthracene compounds, alkenylbenzene compounds, acrylic acid compounds, methacrylic acid compounds, acrylate compounds, methacrylate compounds, N-vinylpyrrole, N-vinylcarbazole, N-vinylimidazol, N-vinylindole, N-vinylpyrrolidone, and trans-N-3-yntynebutenylcarbazole.

17. A holographic optical element, wherein the raw material of the holographic optical element includes the photopolymer type holographic recording medium as described in any one of claims 10-16.

18. A display device comprising the holographic optical element as claimed in claim 17.

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