Photopolymer type holographic recording medium as well as preparation method and application thereof

Abstract

The invention discloses a photopolymer type holographic recording medium and a preparation method and application thereof, the photopolymer type holographic recording medium comprises a writing monomer, and the writing monomer comprises epoxy resin and a polymerizable monomer, the polymerizable monomer is selected from an alkenyl naphthalene compound, an alkenyl anthracene compound, an alkenyl benzene compound, an acrylic acid compound, a methacrylic acid compound, an acrylate compound, a methacrylate compound, N-vinyl pyrrole, N-vinyl carbazole, N-vinyl imidazole, N-vinyl indole and N-vinyl pyrrolidone; the carbazole is at least one of trans-N-3-alkyne butenyl carbazole. According to the epoxy resin disclosed by the invention, the volume shrinkage of the polymerizable monomer after polymerization can be effectively reduced, the cationic polymerization of the epoxy resin can be accelerated while the polymerizable monomer forms free radical polymerization, and the photopolymer type holographic recording medium disclosed by the invention is high in light sensitivity, stable in holographic performance and high in volume holographic grating diffraction efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of holographic materials, in particular to a photopolymer holographic recording medium and a preparation method and application thereof. Background Art

[0002] The various components used to make holographic recording media, such as photosensitive dyes, initiators, chain transfer agents, writing monomers, film-forming resins, plasticizers, etc., work together to determine whether the performance of the holographic recording media is good or not.

[0003] Among the existing photopolymers, some use acrylate monomers or methacrylate monomers as the writing monomer component. The components are single, and the shrinkage rate of the monomer is high after polymerization, which easily leads to large grating offset, thus deviating greatly from the theoretical design value. Some use epoxy resin as the writing monomer component, and its cationic polymerization rate is slow, so that the holographic recording medium prepared by the photopolymer using epoxy resin as the writing monomer has low photosensitivity, making it difficult to prepare high-performance volume holographic gratings. Summary of the invention

[0004] In view of this, the present invention proposes a photopolymer holographic recording medium and a preparation method and application thereof, aiming to achieve that the photopolymer holographic recording medium has higher photosensitivity and stable holographic performance.

[0005] The photopolymer holographic recording medium proposed in the first aspect of the present invention includes a writing monomer, which includes: an epoxy resin; a polymerizable monomer, which is selected from at least one of alkenyl naphthalene compounds, alkenyl anthracene compounds, alkenyl benzene compounds, acrylic compounds, methacrylic compounds, acrylate compounds, methacrylate compounds, N-vinyl pyrrole, N-vinyl carbazole, N-vinylimidazole, N-vinyl indole, N-vinyl pyrrolidone, and trans-N-3-ynyl butenyl carbazole.

[0006] It can be seen from the above technical scheme that the epoxy resin of the present invention and the polymerizable monomer are used together as components of the writing monomer, and the epoxy resin can effectively reduce the volume shrinkage of the polymerizable monomer after polymerization, and can accelerate the cationic polymerization of the epoxy resin while the polymerizable monomer forms free radical polymerization, so that the photopolymer holographic recording medium having the writing monomer of the present invention has a fast polymerization rate after exposure, thereby improving the photosensitivity of the photopolymer holographic recording medium and also improving the holographic performance stability of the photopolymer holographic recording medium.

[0007] In some examples of the present invention, the epoxy resin has a refractive index greater than 1.5 and a viscosity less than 100 mPa·s; and / or the epoxy resin is selected from bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, hydrogenated bisphenol A epoxy resin, propylene glycol triglycidyl ether, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, diglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, pentanediol diglycidyl ether. Oil ether, glycerol triglycidyl ether, 3,4-epoxycyclohexene methyl-3,4-epoxycyclohexene ester, polyethylene glycol diglycidyl ether, diglycidyl ether, diethylene glycol diglycidyl ether, benzyl glycidyl ether, phenyl glycidyl ether, furfuryl glycidyl ether, 2-biphenyl glycidyl ether, pentaerythritol glycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,4-butanediol glycidyl ether, trihydroxymethyl 1,2-cyclohexanediol diglycidyl ether, 2-ethoxyphenyl glycidyl ether, 1,2-cyclohexanediol diglycidyl ether, tetrabromobisphenol A epoxy resin, diglycidyl phthalate, glycidyl p-toluenesulfonate, glycidyl butyrate, glycidyl decanoate, glycidyl octanoate, glycidyl oleate, glycidyl stearate, glycidyl laurate, glycidyl acrylate, glycidyl tert-butyl carbonate, glycidyl palmitate, glycidyl linolenate, glycidyl linoleate, triglycidyl isocyanurate At least one of glyceryl glycidyl ester, hexahydrophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, 4-tert-butylbenzoic acid glycidyl ester, 1-benzyl-4-glycidyl piperazine, isocyanuric acid (S,S,S) triglycidyl ester (refractive index 1.6), 4,5-epoxytetrahydrophthalic acid diglycidyl ester, 4-hydroxybutyl acrylate glycidyl ether, 3-glycidylpropyl (dimethoxy)methylsilane, triglycidylamino-meta-cresol, and triglycidylpara-aminophenol.

[0008] In some embodiments of the present invention, the writing monomer accounts for 10 to 60 parts by weight of the photopolymer holographic recording medium; and / or the photopolymer holographic recording medium further includes a film-forming resin, a photosensitive initiator composition, a chain transfer agent and a catalyst, and the photopolymer holographic recording medium further includes an additive or a solvent.

[0009] In some embodiments of the present invention, the film-forming resin includes cellulose acetate or polyvinyl alcohol; or, the film-forming resin includes a polyisocyanate compound and a polyol compound, wherein the polyisocyanate compound is a compound having at least two isocyanate groups, and the polyol compound is a compound having at least two hydroxyl functional groups.

[0010] In some embodiments of the present invention, the photopolymer holographic recording medium includes the following raw materials of each component in parts by weight: first component: 20 to 60 parts of cellulose acetate or polyvinyl alcohol; second component: 1 to 25 parts of epoxy resin; third component: 5 to 50 parts of polymerizable monomers; fourth component: 0.1 to 4 parts of photosensitive initiator combination agent; fifth component: 0.1 to 3 parts of chain transfer agent; sixth component: 0.1 to 3 parts of catalyst; seventh component: 0.1 to 18 parts of additives or solvents.

[0011] In some embodiments of the present invention, the photopolymer holographic recording medium includes the following raw materials of each component in parts by weight: first component: 20 to 50 parts of polyol compound and 10 to 40 parts of polyisocyanate compound; second component: 3 to 30 parts of epoxy resin; third component: 0.1 to 47 parts of polymerizable monomer; fourth component: 0.1 to 4 parts of photosensitive initiator combination agent; fifth component: 0.1 to 3 parts of chain transfer agent; sixth component: 0.1 to 3 parts of catalyst; seventh component: 0.1 to 18 parts of additive or solvent.

[0012] In some embodiments of the present invention, the photosensitive initiator combination comprises a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the free radical photoinitiator can activate the cationic photoinitiator, and the cationic photoinitiator can initiate the ring-opening of the epoxy resin and the polymerization of the polymerizable monomer; and / or, the chain transfer agent is a thiol compound; and / or, the catalyst is at least one of a tertiary amine catalyst or an organic metal catalyst; and / or, when the photopolymer holographic recording medium comprises additives, the additives comprise one or more of a defoamer, a leveling agent, a plasticizer, an ultraviolet absorber, a light stabilizer and an antioxidant.

[0013] The second aspect of the present invention proposes a method for preparing a photopolymer holographic recording medium in which the film-forming resin in the aforementioned multiple examples is cellulose acetate or polyvinyl alcohol, comprising the following steps: weighing the components of the photopolymer holographic recording medium into a container, and stirring them thoroughly until all the components are dissolved; filtering with a filter membrane to obtain a mixture; coating the mixture on a substrate, and drying it in a dark room at a humidity of 10% to 85% and a temperature of 20° C. to 50° C. to obtain the photopolymer holographic recording medium after the solvent evaporates.

[0014] The preparation method of the photopolymer holographic recording medium proposed in the second aspect of the present invention has few preparation steps, simple operation, easy implementation conditions, and the photopolymer holographic recording medium can be obtained by solvent evaporation. The photopolymer holographic recording medium has high photosensitivity, high diffraction efficiency and stable holographic performance.

[0015] The third aspect of the present invention proposes a method for preparing a photopolymer holographic recording medium in which the film-forming resins in the aforementioned multiple examples are polyol compounds and polyisocyanate compounds, comprising the following steps: weighing the components of the photopolymer holographic recording medium in a container, and stirring them thoroughly until all the components are dissolved; filtering with a filter membrane to obtain a mixture; coating the mixture on a substrate, and curing it in a dark room at a temperature of 10°C to 50°C, and obtaining the photopolymer holographic recording medium after the polyol compounds and polyisocyanate compounds form films.

[0016] The preparation method of the photopolymer holographic recording medium proposed in the third aspect of the present invention has few preparation steps, simple operation, easy implementation conditions, and convenient observation of the progress of film formation. The obtained photopolymer holographic recording medium has high photosensitivity, high diffraction efficiency and stable holographic performance.

[0017] A fourth aspect of the present invention provides a holographic optical element, wherein the material of the holographic optical element includes the photopolymer holographic recording medium of the aforementioned examples.

[0018] The holographic optical element proposed in the fourth aspect of the present invention has excellent holographic performance, high diffraction efficiency, high sensitivity, small exposure amount required, and stable holographic performance.

[0019] A fifth aspect of the present invention provides an optical device, comprising the holographic optical element as described above.

[0020] The optical device proposed in the fifth aspect of the present invention, such as a head-up display device, an augmented reality device, a virtual reality device, a photopolymer holographic storage disc, etc., has excellent and stable holographic performance.

[0021] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure of the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained like these accompanying drawings without paying creative work.

[0023] Figure 1 is a holographic exposure characteristic curve of a photopolymer holographic recording medium in a selected embodiment of the present invention;

[0024] Figure 2 is a holographic exposure characteristic curve of the common photopolymer holographic recording medium in Comparative Examples 1 to 2;

[0025] Figure 3 These are the transmittance curves of the photopolymer holographic recording medium 1-6 of Example 6 and the ordinary photopolymer holographic recording medium 2-2 of Comparative Example 2 measured by using an ultraviolet-visible spectrometer. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0027] The photopolymer material used for holographic recording realizes holographic recording by polymerizing the writing monomers under light and then forming a phase-type holographic grating with refractive index modulation with the film-forming resin. The monomers in the coherent bright area are consumed and the concentration is reduced, while the monomers in the coherent dark area hardly react. The difference in monomer concentration between the bright and dark areas causes the monomers in the dark area to begin to migrate to the bright area, and the film-forming resin in the bright area is squeezed into the dark area. Finally, the refractive index of the bright area is close to that of the polymer, and the refractive index of the dark area is close to that of the film-forming resin, thereby forming a phase-type volume holographic grating with refractive index modulation.

[0028] The present invention provides a writing monomer with a fast polymerization rate and not easy to shrink after polymerization, so that the photopolymer holographic recording medium made of the writing monomer requires a small exposure amount and has a high photosensitivity. The holographic performance of the transmission / reflection volume holographic grating formed after photosensitization is stable and the diffraction efficiency is higher than 95%.

[0029] In the absence of conflict, the following embodiments and features of the embodiments may be combined with each other.

[0030] Next, the photopolymer type holographic recording medium of the present invention will be described.

[0031] The photopolymer holographic recording medium proposed in the present invention includes writing monomers, which include: epoxy resin and polymerizable monomers. The polymerizable monomers are selected from at least one of alkenyl naphthalene compounds, alkenyl anthracene compounds, alkenyl benzene compounds, acrylic compounds, methacrylic compounds, acrylate compounds, methacrylate compounds, N-vinyl pyrrole, N-vinyl carbazole, N-vinyl imidazole, N-vinyl indole, N-vinyl pyrrolidone, and trans-N-3-ynyl butenyl carbazole. That is to say, the writing monomer of the present invention includes at least two monomers, and the two monomers include at least epoxy resin, and also include another monomer that can be rapidly polymerized. The epoxy resin can be ring-opened during the polymerization process and form polymerization with part of the polymerizable monomers, thereby effectively preventing the shrinkage of the polymerizable monomers, and the stability of the writing monomer structure after polymerization is good.

[0032] As can be seen from the above technical scheme, the epoxy resin of the present invention and the polymerizable monomer are used together as components of the writing monomer. The polymerization speed of the polymerizable monomer is fast. The van der Waals distance between some polymerizable monomers that have not reacted before photopolymerization is converted into a covalent bond during polymerization. The epoxy resin opens its ring during photopolymerization and can form a bond with the covalent bond of the polymerizable monomer, thereby effectively reducing the volume shrinkage of the polymerizable monomer after polymerization.

[0033] Since the polymerizable monomer releases energy and forms some free radicals during photopolymerization, the cationic polymerization of the epoxy resin can be accelerated while the polymerizable monomer forms free radicals. As a result, the photopolymer holographic recording medium having the writing monomer of the present invention can have a fast polymerization rate after photopolymerization and maintain a certain structural stability after photopolymerization, thereby improving the photosensitivity of the photopolymer holographic recording medium and also improving the holographic performance stability of the photopolymer holographic recording medium.

[0034] The photopolymer holographic recording medium proposed by the present invention requires a small exposure amount, and the exposure amount is less than 30mJ / cm 2 Transmissive and reflective volume holographic gratings with diffraction efficiencies greater than 95% can be recorded at any time.

[0035] It can be understood that compared with the prior art in which epoxy resin as a single component of the writing monomer has a slower polymerization rate, the present invention contains a multi-component writing monomer, which can achieve a higher polymerization rate after photosensitization, and the structure of the writing monomer after polymerization is relatively stable and not easy to shrink.

[0036] In some embodiments of the present invention, the epoxy resin has a refractive index greater than 1.5 and a viscosity less than 100 mPa·s. As a result, the writing monomer having the epoxy resin selected in the present invention has a higher refractive index and a lower viscosity, a faster migration rate of the writing monomer, and a greater refractive index difference can be formed between the writing monomer and the film-forming resin, which is beneficial for the volume holographic grating to obtain a higher refractive index modulation degree (Δn).

[0037] In other examples, the epoxy resin has a refractive index greater than 1.55 and a viscosity less than 1000 mPa·s, so that the epoxy resin, as one of the components of the writing monomer, can maintain a larger refractive index and a certain viscosity and migration speed when exposed to light.

[0038] In other examples, the refractive index of the epoxy resin of the present invention can also be selected to be lower than 1.5. After the epoxy resin in these examples is combined with some polymerizable monomers with a larger refractive index, the refractive index of the writing monomer formed can be increased.

[0039] In some embodiments of the present invention, the epoxy resin is selected from bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, hydrogenated bisphenol A epoxy resin, glycerol triglycidyl ether, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, diglycidyl ester (refractive index 1.55), ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, pentanediol diglycidyl ether, glycerol triglycidyl ether, 3, 4-Epoxycyclohexenemethyl-3,4-epoxycyclohexene ester, polyethylene glycol diglycidyl ether, diglycidyl ether, diethylene glycol diglycidyl ether, benzyl glycidyl ether, phenyl glycidyl ether, furfuryl glycidyl ether, 2-biphenyl glycidyl ether, pentaerythritol glycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,4-butanediol glycidyl ether, trimethylolethane triglycidyl ether Oil ether, 2-ethoxyphenyl glycidyl ether, 1,2-cyclohexanediol diglycidyl ether, tetrabromobisphenol A epoxy resin, diglycidyl phthalate, glycidyl p-toluenesulfonate, glycidyl butyrate, glycidyl decanoate, glycidyl octanoate, glycidyl oleate, glycidyl stearate, glycidyl laurate, glycidyl acrylate, glycidyl tert-butyl carbonate, glycidyl palmitate, glycidyl linolenate, glycidyl linoleate, triisocyanurate At least one of glycidyl ester, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, glycidyl 4-tert-butylbenzoate, 1-benzyl-4-glycidyl piperazine, triglycidyl isocyanurate (S,S,S), diglycidyl 4,5-epoxytetrahydrophthalate, 4-hydroxybutyl acrylate glycidyl ether, 3-glycidylpropyl (dimethoxy) methyl silane, triglycidyl amino-meta-cresol, and triglycidyl p-aminophenol. As can be seen from the foregoing, the present invention can specifically select an epoxy resin with a refractive index greater than 1.55 to make the refractive index of the writing monomer larger. It is understandable that the epoxy resins listed above are all resin compounds having at least one active reactive epoxy group, which can be ring-opened during the polymerization reaction to react with polymerizable monomers or other components to form a chain or network structure, thereby making the structure after the polymerization reaction more stable.For example, in some examples, the resin compound containing one active reactive epoxy group is n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, 4-tert-butylbenzoic acid glycidyl ether, etc.; the resin compound containing two active reactive epoxy groups is diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, pentanediol diglycidyl ether, etc.; the resin compound containing three active reactive epoxy groups is glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, isocyanuric acid triglycidyl ether, isocyanuric acid (S, S, S) triglycidyl ester, triglycidyl amino-meta-cresol, triglycidyl p-aminophenol, etc. In a specific example, an epoxy resin with a refractive index greater than 1.5 is preferred, such as diglycidyl ether, phenyl glycidyl ether, resorcinol diglycidyl ether, etc.

[0040] In some embodiments of the present invention, the weight of the writing monomer accounts for 10 to 60 parts of the weight of the photopolymer holographic recording medium. When the weight of the writing monomer accounts for the weight of the photopolymer holographic recording medium within the above range, the writing monomer can have a sufficient concentration, so that there are enough writing monomers to participate in the reaction, ensuring a faster polymerization rate; at the same time, a larger concentration difference between the bright area and the dark area formed after the reaction under light can be achieved, and under the driving effect of a larger concentration gradient, the speed at which the writing monomer migrates from the coherent dark area to the coherent bright area will be accelerated. In addition, when the weight of the writing monomer accounts for the weight of the photopolymer holographic recording medium within the above range, the film-forming resin can also load the writing monomer and can finally polymerize to form a solid film under the action of exposure, thereby effectively ensuring the quality of the formed volume holographic grating.

[0041] Furthermore, the photopolymer holographic recording medium of the present invention also includes a film-forming resin, a photosensitive initiator composition, a chain transfer agent and a catalyst, and the photopolymer holographic recording medium also includes an additive or a solvent. The film-forming resin and the writing monomer can form a refractive index modulated grating with a refractive index difference; the photosensitive initiator composition can absorb light energy and transfer energy to other components after exposure, quickly induce the polymerization of the writing monomer to form a volume holographic grating; the chain transfer agent can control the length of the polymer chain; the catalyst can effectively increase the reaction rate of the related components; the additives can be added in different types according to the needs of the reaction system; the solvent can improve the solubility of each component and the dispersion of each component in the whole system, so as to facilitate the preparation of a photopolymer holographic recording medium with stable holographic performance. The synergistic effect of each component can form a photopolymer holographic recording medium with good holographic performance.

[0042] In some embodiments of the present invention, the film-forming resin includes cellulose acetate or polyvinyl alcohol, both of which are volatile. The thickness of the photopolymer prepared by using the volatile film-forming resin is relatively thin.

[0043] In other examples of the present invention, the film-forming resin includes a polyisocyanate compound and a polyol compound, wherein the polyisocyanate compound is a compound having at least two isocyanate groups, and the polyol compound is a compound having at least two hydroxyl functional groups. The film-forming resin in these examples is of a second-order reaction type, is easy to process, and has good dimensional stability.

[0044] Next, a photopolymer type holographic recording medium including a volatile film-forming resin is described.

[0045] In some embodiments of the present invention, a photopolymer holographic recording medium including a volatile film-forming resin includes the following raw materials of each component in parts by weight: a first component: 20 to 60 parts of cellulose acetate or polyvinyl alcohol; a second component: 1 to 25 parts of epoxy resin; a third component: 5 to 50 parts of polymerizable monomers; a fourth component: 0.1 to 4 parts of a photosensitive initiator combination agent; a fifth component: 0.1 to 3 parts of a chain transfer agent; a sixth component: 0.1 to 3 parts of a catalyst; and a seventh component: 0.1 to 18 parts of an additive or a solvent.

[0046] For example, the first component cellulose acetate or polyvinyl alcohol can be 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, etc. By reasonably controlling the addition amount of the first component, the required support can be provided for the other components, and the film-forming resin composed of the above components of the present application is relatively thin.

[0047] The second component epoxy resin can be 1 part, 2 parts, 3 parts, 5 parts, 10 parts, 15 parts, 20 parts, 22 parts, 24 parts, 25 parts, etc. The third component polymerizable monomer can be 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 50 parts, etc. By reasonably controlling the addition amount of the second component and the third component, the two together constitute the writing monomer, which can ensure that the writing monomer has a sufficient concentration, so that there are enough writing monomers to participate in the reaction, ensure a faster polymerization rate, and the size after polymerization is relatively stable and not easy to shrink, so that the formed volume holographic grating has stable performance. It also enables the film-forming resin to load and support the writing monomer, and a certain refractive index difference can be formed between the film-forming resin and the writing monomer.

[0048] The fourth component, the photosensitive initiator composition, can be 0.1 parts, 0.2 parts, 0.3 parts, 0.5 parts, 1 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4 parts, etc. By properly controlling the amount of the fourth component added, a suitable number of photons can be absorbed during exposure, and the polymerization reaction can be controlled at a certain speed, so that the grating can be formed quickly and a higher diffraction efficiency can be obtained; in addition, it can also ensure that the final holographic recording medium has the required light transmittance.

[0049] The fifth component chain transfer agent can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, etc. By properly controlling the addition amount of the fifth component, the polymer chain length can be controlled within a certain reasonable range, and the polymerization degree can be effectively prevented from being too high, ensuring that the final holographic recording medium has the required optical properties and diffraction efficiency.

[0050] The sixth component catalyst can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, etc. By reasonably controlling the addition amount of the sixth component, the reaction rate of the relevant components can be effectively increased, and the consumption rate of the relevant components after exposure can be increased, thereby quickly forming a concentration difference between the monomers in the bright area and the dark area, and realizing a phase-type volume holographic grating with refractive index modulation.

[0051] The seventh component additive or solvent can be 0.1 parts, 0.2 parts, 0.3 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 12 parts, 15 parts, 18 parts, etc.

[0052] If the seventh component is an additive, for example, the additive is a leveling agent, by controlling the amount of the leveling agent added within the above range, the uniformity of the mixed liquid can be effectively improved, the fluidity can be improved, and the cost can be reasonably controlled. In some examples, the weight of the leveling agent in the photopolymer holographic recording medium is less than or equal to 3 parts.

[0053] Taking the additive as a plasticizer as an example, by controlling the amount of the plasticizer added within the above range, the plasticizer is inserted between polymer molecular chains, weakens the stress between molecules, increases the mobility of the molecular chains, and reduces the crystallinity, thereby increasing the plasticity of the polymer. In some examples, the weight percentage of the plasticizer in the photopolymer holographic recording medium is less than or equal to 3 parts.

[0054] Taking the additive as a defoamer as an example, by controlling the amount of the defoamer added within the above range, the defoamer can reduce the surface tension of the liquid and remove bubbles, thereby improving the fluidity of the mixture of the components. In some examples, the defoamer accounts for less than or equal to 3 parts by weight of the photopolymer holographic recording medium.

[0055] Taking the additive as an ultraviolet absorber as an example, by controlling the amount of the ultraviolet absorber added within the above range, the ultraviolet absorber can absorb ultraviolet rays, so that the photopolymer holographic recording medium is protected from aging or photolysis under ultraviolet rays, thereby improving the performance stability of the photopolymer holographic recording medium. In some examples, the ultraviolet absorber accounts for less than or equal to 3 parts by weight of the photopolymer holographic recording medium.

[0056] Taking the additive as a light stabilizer as an example, by controlling the amount of the light stabilizer added within the above range, the light stabilizer can absorb ultraviolet rays and convert them into heat energy, and can also release active substances and inhibit free radical reactions in the process of absorbing ultraviolet energy, effectively preventing the photopolymer holographic recording medium from changing color under ultraviolet irradiation, thereby maintaining the original color and gloss of the photopolymer holographic recording medium, improving the weather resistance of the photopolymer holographic recording medium, and extending the service life. In some examples, the weight of the light stabilizer in the photopolymer holographic recording medium is less than or equal to 3 parts.

[0057] Taking the antioxidant as an example, by controlling the amount of the antioxidant added within the above range, the antioxidant can produce a synergistic effect with the ultraviolet absorber to improve the weather resistance and thermal oxygen stability of the photopolymer holographic recording medium, and effectively delay the aging and degradation of the photopolymer holographic recording medium. In some examples, the antioxidant accounts for less than or equal to 3 parts by weight of the photopolymer holographic recording medium.

[0058] If the seventh component is a solvent, by controlling the proportion of the solvent within the above range, the solvent can fully wet the other components and make the components mutually soluble to form a relatively uniform mixed system, which is convenient for coating and making photopolymer holographic recording media.

[0059] Next, a photopolymer type holographic recording medium including a second-stage reaction type film-forming resin is described.

[0060] In other examples of the present invention, a photopolymer holographic recording medium including a second-order reaction type film-forming resin includes the following raw materials of each component in parts by weight: a first component: 20 to 50 parts of a polyol compound and 10 to 40 parts of a polyisocyanate compound; a second component: 3 to 30 parts of an epoxy resin; a third component: 0.1 to 47 parts of a polymerizable monomer; a fourth component: 0.1 to 4 parts of a photosensitive initiator combination agent; a fifth component: 0.1 to 3 parts of a chain transfer agent; a sixth component: 0.1 to 3 parts of a catalyst; and a seventh component: 0.1 to 18 parts of an additive or a solvent.

[0061] For example, the polyol compound in the first component can be 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 44 parts, 47 parts, 50 parts, etc.; the polyisocyanate compound in the first component can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, etc. By controlling the addition amount of each substance in the first component within the above range, the first component can form a film-forming resin with a lower refractive index, thereby providing support for other components.

[0062] The second component epoxy resin can be 3 parts, 4 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, etc. The third component polymerizable monomer can be 0.1 parts, 0.3 parts, 1 parts, 2 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 40 parts, 47 parts, etc. By controlling the addition amount of the second component and the third component within the above range and selecting a suitable addition amount, the second component and the third component can be polymerized at a fast rate after exposure, and the structure is stable and not easy to shrink after polymerization, and the writing monomer has a higher refractive index and can form a certain refractive index difference with the film-forming resin, so that the photopolymer holographic recording medium containing the second component and the third component has high sensitivity, can quickly form a volume holographic grating, and the formed volume holographic grating has stable holographic performance.

[0063] The addition amounts and functions of the fourth component, the fifth component, the sixth component and the seventh component in the photopolymer holographic recording medium including a second-order reaction type film-forming resin are similar to the addition amounts and functions of the corresponding components in the photopolymer holographic recording medium including a volatile film-forming resin, and are not elaborated here.

[0064] It can be seen from the above that by reasonably controlling the addition amount of each component of the photopolymer holographic recording medium in each embodiment, the various components can fully cooperate with each other, and the holographic performance of the final photopolymer holographic recording medium will not be deteriorated due to too much or too little of a certain component, thereby ensuring that the comprehensive holographic performance of the final photopolymer holographic recording medium is better.

[0065] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 20 parts of cellulose acetate, a second component - 18 parts of epoxy resin, a third component - 49 parts of polymerizable monomers, a fourth component - 2 parts of photosensitive initiator composition, a fifth component - 1 part of chain transfer agent, a sixth component - 2 parts of catalyst, and a seventh component - 8 parts of additives.

[0066] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 30 parts of cellulose acetate, a second component - 25 parts of epoxy resin, a third component - 39 parts of polymerizable monomers, a fourth component - 2 parts of photosensitive initiator composition, a fifth component - 0.3 parts of chain transfer agent, a sixth component - 0.4 parts of catalyst, and a seventh component - 3 parts of additives.

[0067] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 40 parts of cellulose acetate, a second component - 20 parts of epoxy resin, a third component - 35 parts of polymerizable monomers, a fourth component - 2 parts of photosensitive initiator composition, a fifth component - 1 part of chain transfer agent, a sixth component - 1 part of catalyst, and a seventh component - 1 part of additive.

[0068] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 50 parts of cellulose acetate, a second component - 15 parts of epoxy resin, a third component - 30 parts of polymerizable monomers, a fourth component - 1 part of photosensitive initiator composition, a fifth component - 0.1 parts of chain transfer agent, a sixth component - 2 parts of catalyst, and a seventh component - 1.9 parts of solvent.

[0069] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 57.8 parts of polyvinyl alcohol, a second component - 4 parts of epoxy resin, a third component - 32 parts of polymerizable monomers, a fourth component - 1 part of photosensitive initiator composition, a fifth component - 3 parts of chain transfer agent, a sixth component - 0.3 parts of catalyst, and a seventh component - 1.9 parts of solvent.

[0070] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 60 parts of polyvinyl alcohol, a second component - 20 parts of epoxy resin, a third component - 10 parts of polymerizable monomers, a fourth component - 1 part of photosensitive initiator composition, a fifth component - 1 part of chain transfer agent, a sixth component - 1 part of catalyst, and a seventh component - 7 parts of additives.

[0071] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 42 parts of polyvinyl alcohol, a second component - 5 parts of epoxy resin, a third component - 50 parts of polymerizable monomers, a fourth component - 1 part of photosensitive initiator composition, a fifth component - 0.2 parts of chain transfer agent, a sixth component - 1 part of catalyst, and a seventh component - 0.8 parts of solvent.

[0072] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 22 parts of polyvinyl alcohol, a second component - 5 parts of epoxy resin, a third component - 45 parts of polymerizable monomers, a fourth component - 4 parts of photosensitive initiator composition, a fifth component - 3 parts of chain transfer agent, a sixth component - 3 parts of catalyst, and a seventh component - 18 parts of additives.

[0073] In some optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 30 parts of polyvinyl alcohol, a second component - 11 parts of epoxy resin, a third component - 46 parts of polymerizable monomers, a fourth component - 2 parts of photosensitive initiator composition, a fifth component - 2 parts of chain transfer agent, a sixth component - 3 parts of catalyst, and a seventh component - 6 parts of additives.

[0074] In some other optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 50 parts of a polyol compound, 10 parts of a polyisocyanate compound, a second component - 12 parts of an epoxy resin, a third component - 18 parts of a polymerizable monomer, a fourth component - 1 part of a photosensitive initiator composition, a fifth component - 1 part of a chain transfer agent, a sixth component - 2 parts of a catalyst, and a seventh component - 6 parts of an additive.

[0075] In some other optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 22 parts of a polyol compound, 37 parts of a polyisocyanate compound, a second component - 3 parts of an epoxy resin, a third component - 23 parts of a polymerizable monomer, a fourth component - 4 parts of a photosensitive initiator composition, a fifth component - 1 part of a chain transfer agent, a sixth component - 2 parts of a catalyst, and a seventh component - 8 parts of an additive.

[0076] In some other optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 20 parts of a polyol compound, 40 parts of a polyisocyanate compound, a second component - 30 parts of an epoxy resin, a third component - 0.1 parts of a polymerizable monomer, a fourth component - 4 parts of a photosensitive initiator composition, a fifth component - 0.1 parts of a chain transfer agent, a sixth component - 3 parts of a catalyst, and a seventh component - 2.8 parts of a solvent.

[0077] In some other optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 25 parts of a polyol compound, 20 parts of a polyisocyanate compound, a second component - 3 parts of an epoxy resin, a third component - 47 parts of a polymerizable monomer, a fourth component - 0.1 parts of a photosensitive initiator composition, a fifth component - 0.1 parts of a chain transfer agent, a sixth component - 0.1 parts of a catalyst, and a seventh component - 4.7 parts of an additive.

[0078] In some other optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 20 parts of a polyol compound, 20 parts of a polyisocyanate compound, a second component - 10 parts of an epoxy resin, a third component - 30 parts of a polymerizable monomer, a fourth component - 0.2 parts of a photosensitive initiator composition, a fifth component - 3 parts of a chain transfer agent, a sixth component - 0.8 parts of a catalyst, and a seventh component - 16 parts of an additive.

[0079] In some other optional examples, the photopolymer holographic recording medium includes the following components in parts by weight: a first component - 27 parts of a polyol compound, 22 parts of a polyisocyanate compound, a second component - 13 parts of an epoxy resin, a third component - 19 parts of a polymerizable monomer, a fourth component - 0.2 parts of a photosensitive initiator composition, a fifth component - 0.3 parts of a chain transfer agent, a sixth component - 0.5 parts of a catalyst, and a seventh component - 18 parts of an additive.

[0080] In some examples of the present invention, the cellulose acetate in the volatile film-forming resin is a man-made fiber obtained by esterification reaction of acetic acid and cellulose. It can be cellulose acetate, cellulose diacetate, and cellulose triacetate. That is, the degree of esterification reaction between acetic acid and cellulose is different. When the content of acetic acid is higher, the hydroxyl group contained in cellulose acetate is less. The cellulose acetate added in the present invention is preferably cellulose acetate with certain hydroxyl groups.

[0081] In some examples of the present invention, polyvinyl alcohol (also known as PVA) in the volatile film-forming resin is a small molecule compound with hydroxyl active groups and is soluble in water. It is used in photopolymer holographic recording media with a faster migration rate between coherent dark areas and related bright areas.

[0082] In some examples of the present invention, the reactive functional group of the polyol compound is an alcoholic hydroxyl group, which is easily oxidized and has a high reaction activity; for example, in some examples, the polyol compound is a compound with a low refractive index and two or more hydroxyl functional groups.

[0083] More specifically, the polyol compound is selected from at least one of tetraethylene glycol, trimethylolethane, glycerol, triethanolamine, polyester polyols with a molecular weight of 200 to 2000, polycarbonate polyols, and polyether polyols. These substances have a relatively low refractive index, for example, the refractive index of tetraethylene glycol is 1.46 (20° C.); the refractive index of trimethylolethane is 1.5; the refractive index of glycerol is 1.474 (20° C.); and the refractive index of triethanolamine is 1.482 to 1.485 (20° C.).

[0084] In some examples of the present invention, the polyisocyanate compound is a compound with a low refractive index and two or more isocyanate groups. The isocyanate group is highly active and can react with the hydroxyl group in the polyol to form a covalent bond and polymerize. The more isocyanate groups there are, the higher the activity is. A single molecule can react with multiple hydroxyl groups, the faster the reaction speed is, and the addition of the polyisocyanate compound is saved.

[0085] In a specific example, the polyisocyanate compound is selected from at least one of hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tris(hexamethylene)isocyanate, butane-1,4-diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate. The refractive index of these compounds is also low: the refractive index of hexamethylene diisocyanate is 1.453; the refractive index of trimethylhexamethylene diisocyanate is 1.462; the refractive index of (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tris(hexamethylene)isocyanate is 1.462; the refractive index of butane-1,4-diisocyanate is 1.484; the refractive index of isophorone diisocyanate is 1.484; and the refractive index of dicyclohexylmethane diisocyanate is 1.496 (25°C).

[0086] Some optional compounds of the polymerizable monomers of the present invention are described below. These examples are merely illustrative and should not be construed as limiting the present invention.

[0087] In a specific example, the alkenyl naphthalene compound is selected from at least one of 1-vinyl naphthalene and 2-vinyl naphthalene.

[0088] In a specific example, the alkenyl anthracene compound is selected from at least one of 2-vinyl anthracene and 9-vinyl anthracene.

[0089] In a specific example, the alkenylbenzene compound is selected from at least one of styrene, 2-chlorostyrene, 2-bromostyrene, 3-chlorostyrene, 3-bromostyrene, 4-chlorostyrene, 4-bromostyrene, p-(chloromethyl)styrene, and p-(bromomethyl)styrene.

[0090] In a specific example, the methacrylic compound includes at least one of methacrylic acid and derivatives thereof.

[0091] In a specific example, the acrylate compound is selected from at least one of pentabromophenyl acrylate, pentachlorophenyl acrylate, phenoxyethyl acrylate, pentabromobenzyl acrylate, 2-naphthyl acrylate, 1,4-di(2-thionaphthyl)2-butyl acrylate, phenoxyethoxyethyl acrylate, bisphenol A diacrylate, tetrabromobisphenol A diacrylate, 2-phenoxyethyl acrylate, benzyl acrylate, p-chlorophenyl acrylate, 2,4,6-trichlorophenyl acrylate, p-bromophenyl acrylate, 2,4,6-tribromophenyl acrylate, propane-2,2-diylbis[(2,6-dibromo-4,1-phenylene)oxy(2-{[3,3,3-tri(4-chlorophenyl)propionyl]oxy}propane-3,1-diyl)oxyethane-2,1-diyl]diacrylate.

[0092] In a specific example, the methacrylate compound is selected from at least one of 2-phenoxyethyl methacrylate, benzyl methacrylate, p-bromophenyl methacrylate, p-chlorophenyl methacrylate, 2,4,6-trichlorophenyl methacrylate, pentabromophenyl methacrylate, pentachlorophenyl methacrylate, phenoxyethyl methacrylate, phenoxyethoxyethyl methacrylate, 1,4-di(2-thionaphthyl) 2-butyl methacrylate, pentabromobenzyl methacrylate, 2-naphthyl methacrylate, bisphenol A dimethacrylate, and tetrabromobisphenol A dimethacrylate.

[0093] When there are two or more polymerizable monomers in the present invention, they can be combined in any ratio.

[0094] In some examples of the present invention, the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator. The photosensitizer absorbs light energy and induces the free radical photoinitiator to cleave. The free radical photoinitiator can activate the cationic photoinitiator, and the cationic photoinitiator can initiate the ring opening of the epoxy resin and the polymerization of the polymerizable monomer. The photosensitizer can be matched with the free radical photoinitiator and the cationic photoinitiator to realize the visible light initiation system and adapt to lasers of different wavelengths. Under the irradiation of light in a specific wavelength range, the photosensitizer in the photoinitiator system is activated by the corresponding light, absorbs light energy, and transfers the light energy to the free radical photoinitiator. The cleaved free radical photoinitiator activates the cationic photoinitiator through electron transfer, so that the free radical photoinitiator and the cationic photoinitiator can be activated under more frequency light radiation, generating free radicals and cations with initiation function, and then can initiate the polymerization of the polymerizable monomer and the epoxy resin to realize the construction of the holographic grating, improve the photosensitivity of the photopolymer holographic recording medium, and broaden the optional range of radiation sources of light radiation.

[0095] Then, it can be understood that in other examples, when the present invention uses a free radical photoinitiator and a cationic photoinitiator with adapted wavelengths, no photosensitizer may be added. For example, when the absorption wavelength of the free radical photoinitiator or the absorption wavelength of the cationic photoinitiator is greater than 400nm, it can absorb light with a longer wavelength and is easy to be activated, and no photosensitizer may be added at this time.

[0096] In some examples, the photosensitizer is selected from at least one of cyanine dyes, fluorescein dyes, coumarin ketone dyes, nitrogen-containing aromatic heterocyclic compounds, aromatic amine compounds, and benzylcycloalkane ketone compounds.

[0097] More specifically, the photosensitizer is selected from one or more of new methylene blue, thionine, basic yellow, chlorinated pinacol cyanol, rhodamine 6G, eosin Y, gallocyanine, ethyl violet, Victoria blue R, lapis lazuli blue, methylene blue, basic orange, daro red, pyrrole red Y, basic red 29, quinaldine red, crystal violet, ethyl violet, brilliant green, azure A, crystal violet white nitrile, malachite green white nitrile, etc. In the present invention, different broadband responses can be achieved by regulating the types of photosensitizers. Photosensitizers are dyes with high electron transfer efficiency under illumination.

[0098] In some specific examples, the free radical photoinitiator is selected from one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methylphenylpropane-1-one, ethyl p-dimethylaminobenzoate, phenyl (2,4,6-trimethylbenzoyl) phosphate lithium salt, 2,2-dimethoxy-phenylacetophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the like. When these free radical photoinitiators are irradiated by light within the corresponding wavelength range, they can be quickly activated and generate active free radicals, thereby initiating polymerization reactions between the components of the photopolymer holographic recording medium and achieving a difference in monomer concentration between the bright area and the dark area.

[0099] In some specific examples, the cationic photoinitiator is an ultraviolet photoinitiator that initiates cationic ring-opening polymerization of epoxy resin, including but not limited to diaryliodonium salts, triarylsulfonium salts, and ferrocenium salt compounds.

[0100] In some examples, the mass ratio of the photosensitizer to the free radical photoinitiator or the cationic photoinitiator is (0.001-1):(0.1-3). By controlling the mass ratio of the photosensitizer to the free radical photoinitiator or the cationic photoinitiator within the above range, the concentration of the photosensitizer can be effectively controlled, so that during the holographic exposure process, the number of absorbed photons is controlled within a suitable range, the speed of the polymerization reaction is controlled within a reasonable range, and the speed of grating formation is controlled within a certain range, thereby ensuring the light transmittance of the photopolymer holographic recording medium and obtaining excellent diffraction efficiency. In a more specific example, the mass of the photosensitizer is 1 / 10 to 1 / 3 of the mass of the free radical photoinitiator or the cationic photoinitiator, such as 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4 or 1 / 3, etc.

[0101] In some examples of the present invention, the chain transfer agent is a thiol compound.

[0102] In a specific example, the chain transfer agent includes one or more of dodecyl mercaptan, mercaptoethanol, hexanethiol, phenylethyl mercaptan, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 4-methyl-4H-1,2,4-triazole-3-thiol, and the like.

[0103] In some examples of the present invention, the catalyst is a tertiary amine catalyst and an organometallic catalyst.

[0104] In a specific example, the catalyst is selected from at least one of triethylenediamine, bis(dimethylaminoethyl) ether, dimethylethanolamine, 2-(2-dimethylamino-ethoxy)ethanol, trimethylhydroxyethylpropylenediamine, N,N-bis(dimethylaminopropyl)isopropanolamine, dibutyltin dilaurate, stannous octoate, potassium carboxylate catalysts and bismuth carboxylate catalysts.

[0105] In some examples of the present invention, as mentioned above, the additive includes one or more of a defoamer, a leveling agent, a plasticizer, a UV absorber, a light stabilizer, and an antioxidant.

[0106] In a specific example, the defoaming agent is a silicone defoaming agent and / or a polymer defoaming agent that does not contain silicone. The function of the defoaming agent is as described above and will not be described in detail here.

[0107] For example, BYK-011, BYK-012, BYK-014, BYK-023, BYK-051N, BYK-085, BYK-1610, BYK-1707, BYK-1740, BYK-1760 produced by BYK, DC65, AFE-7820 produced by Dow Corning, or any mixture of these defoamers. BYK series defoamers have excellent defoaming performance, good compatibility with other components, and good dispersibility; BYK-011, BYK-012, BYK-014 and BYK-051N are polymer defoamers without silicone. DC65 is a water-based ink that dries quickly, has good printing effect, and is not easy to fall off. AFE-7820 has high efficiency in defoaming performance.

[0108] In a specific example, the leveling agent is an organic silicon 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 produced by BYK. BYK series leveling agents have excellent leveling properties.

[0109] In a specific example, the plasticizer is selected from at least one of toluene, xylene, dimethylformamide, dimethylacetamide, glycerol, and phthalates. The function of the plasticizer is as described above and will not be described in detail here.

[0110] In a specific example, the ultraviolet absorber includes, but is not limited to, 2-hydroxy-4-n-octyloxybenzophenone, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-oxalamide, 2-(2H-benzotriazole-2-yl)-p-cresol, 2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol, 2-(2H-benzotriazole-2)-4,6-di(1-methyl-1-phenylethyl)phenol, or any mixture of these additives. The function of the ultraviolet absorber is as described above and will not be repeated here.

[0111] In a specific example, 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. The function of the light stabilizer is as described above and will not be described in detail here.

[0112] In a specific example, the antioxidant includes but is not limited to any one or more of 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, and Irganox Borchors Ascinin@P. When there are multiple antioxidants, they can be any mixture of these antioxidants in any proportion under the premise of meeting the synergistic effect after compounding. The functions of the antioxidants are as described above and will not be repeated here.

[0113] Irganox 1010 is a BASF antioxidant, which has strong anti-extraction ability, low volatility, good solubility with other components, no color pollution and will not color the product.

[0114] Irganox 168 is a BASF antioxidant that is not easy to change color, has strong hydrolysis resistance, is not easy to volatilize, and is not easy to produce bubbles during use. Irganox 168 is an organic phosphite auxiliary antioxidant that can be compounded with Irganox 1010 and Irganox 1010 to produce a synergistic effect and effectively prevent the thermal degradation of each component during the polymerization process.

[0115] Irganox 1076 is a BASF antioxidant, a highly efficient hindered phenol antioxidant, which has good compatibility with most polymers and can effectively prevent product discoloration caused by light and heat. BASF antioxidant 1076 can be used in combination with auxiliary antioxidants such as AT-168 and DLTDP to achieve a synergistic effect and improve the antioxidant effect.

[0116] Irganox 1098 is a BASF antioxidant, a hindered phenol antioxidant with low volatility and no color stain.

[0117] Irganox MD1024 is a BASF antioxidant, a stabilizer and highly efficient metal deactivator used in organic copolymers. It does not produce color stains and can be used alone or mixed with phenolic antioxidants.

[0118] Irganox 1035 is a sulfur-containing hindered phenol antioxidant and heat stabilizer. BASF Liquid Antioxidant 1135 is a liquid hindered phenol antioxidant suitable for polyols, polyurethanes and other polymers.

[0119] BASF's liquid antioxidant Irganox 1135 is an excellent antioxidant suitable for various polymers. It is used in polyurethane soft foam sheets to prevent polyols from generating peroxides during storage.

[0120] Irganox B225 is an antioxidant with good performance, which has outstanding processing stability and long-term protection for polyolefins.

[0121] Irganox PS800 is a processing stabilizer for dialkyl thiodipropionic acid, which is usually used in combination with phenolic antioxidants in organic compounds. Irganox PS800 is usually mixed with phenolic antioxidants to enhance aging stability and light stability. In a specific example, the added amount is 0.2% to 1% by weight of the photopolymer holographic recording medium.

[0122] Irganox B 900 is a compound mixture, including 80% Irgafos 168 and 20% Irganox 1076. It is mainly used for polyethylene and ethylene copolymers, such as ethylene vinyl acetate copolymers. The compound synergist can also be used for other polymers, such as engineering plastics, polycarbonate, polyester, styrene homopolymer and copolymer, polyurethane, etc. In a specific example, the addition amount is 0.1% to 0.3% by weight of the photopolymer holographic recording medium.

[0123] Irganox 3114 is a BASF antioxidant that can prevent polymers from aging due to heat and oxidation, and also has light resistance. BASF antioxidant 3114 is suitable for polyolefins such as polyethylene, polypropylene and polybutylene, as well as styrene homopolymers and copolymers. It can also be used in other organic matrices such as linear polyesters, PVC, polyamides and polyurethanes. It is soluble in acetone, benzene, chloroform, N,N-dimethylformamide, ethanol and methanol.

[0124] Irganox 245 is a highly effective hindered phenolic antioxidant that effectively prevents thermal oxidative degradation of polymers. It can be used in combination with auxiliary antioxidants (such as thioethers, phosphites, phosphonates, furanones), light stabilizers and other functional stabilizers. The combined use of Irganox 245 and Irgafos 168 has a better effect.

[0125] Irganox B215 is a synergistic compound consisting of hindered phenol and phosphite complex. It has the low volatility and hydrolysis resistance of organic phosphite antioxidant 168, as well as the processing stability and long-term thermal stability of antioxidant 1010. It can be used with other additives such as UV absorbers and light stabilizers to enhance their effects. It is suitable for olefin copolymers and polyolefins.

[0126] Irganox PS-802FL is a dialkyl ester of thiodipropionic acid, which is a secondary antioxidant. It can be used as a synergist with phenolic antioxidants to improve the effect of phenolic antioxidants. Thiodipropionic acid esters are very effective in polyolefins such as polypropylene, polyethylene, impact polystyrene and other organic substances.

[0127] Irganox Borchors Ascinin@P is a BASF antioxidant with excellent thermal oxidation stability.

[0128] In some embodiments of the present invention, when the seventh component is a solvent, the weight percentage of the solvent in the photopolymer holographic recording medium is less than or equal to 3 parts.

[0129] In a specific embodiment, the solvent is selected from at least one of petroleum ether, dichloromethane, ethyl acetate, n-hexane, tetrahydrofuran, acetone, benzene, methyl ethyl ketone, methyl formate, methyl propionate, isobutyl formate, butyl chloride, ethyl propionate, ethylene dichloride, chloroisopentane, methyl carbonate, trichloroethane, carbon tetrachloride, ethylene dichloride, carbon disulfide, 3-propanol pentanone, dichloropropane, butanone, ethyl bromide, and cyclohexane. These solvents have good compatibility with other components, so that each component is fully dissolved, and the solvent is easy to remove by subsequent drying.

[0130] Next, a method for preparing the photopolymer type holographic recording medium of the present invention comprising the aforementioned volatilized film-forming resin will be described.

[0131] The method for preparing the photopolymer holographic recording medium according to the present invention comprises the following steps:

[0132] Step S10, weighing the raw materials of the components of the photopolymer holographic recording medium (cellulose acetate or polyvinyl alcohol, epoxy resin, polymerizable monomer, photosensitive initiator combination agent, chain transfer agent, catalyst, additive or solvent) into a container, and stirring thoroughly until all the components are dissolved.

[0133] Step S20, filtering using a filter membrane to obtain a mixture.

[0134] Step S30, coating the mixture onto a substrate, and drying it in a dark room at a humidity of 10% to 85% and a temperature of 20° C. to 50° C. to obtain a photopolymer holographic recording medium after the solvent evaporates.

[0135] As can be seen from the above, the preparation method of the photopolymer holographic recording medium proposed in the present invention has few preparation steps, simple operation, easy implementation conditions, and solvent evaporation to obtain a photopolymer holographic recording medium with high photosensitivity, high diffraction efficiency and good weather resistance.

[0136] Next, a method for preparing a photopolymer type holographic recording medium comprising a second-stage reaction type film-forming resin according to the present invention will be described.

[0137] Step S100, weighing the raw materials of various components of the photopolymer holographic recording medium (polyol compound and polyisocyanate compound, epoxy resin, polymerizable monomer, photosensitive initiator combination agent, chain transfer agent, catalyst, additive or solvent) into a container, and stirring thoroughly until all components are dissolved.

[0138] Step S200, filtering with a filter membrane to obtain a mixture.

[0139] Step S300, coating the mixture onto a substrate, and curing the mixture in a dark room at a temperature of 10°C to 50°C, and obtaining a photopolymer holographic recording medium after the polyol compound and the polyisocyanate compound form a film.

[0140] It can be seen from the above that the preparation method of the photopolymer holographic recording medium proposed in the present invention has fewer preparation steps, simple operation, easy implementation conditions, and convenient observation of the progress of film formation. The obtained photopolymer holographic recording medium has high photosensitivity, high diffraction efficiency and stable holographic performance.

[0141] Next, the application of the aforementioned photopolymer type holographic recording medium of the present invention will be described.

[0142] The holographic optical element proposed by the present invention is made of materials including the photopolymer holographic recording media in the above-mentioned examples. The holographic optical element includes but is not limited to a volume holographic grating.

[0143] From the above, it can be seen that the holographic optical element proposed in the present invention, because it contains the photopolymer holographic recording medium mentioned above in the present invention, also has the advantages of the photopolymer holographic recording medium of the present invention, has excellent holographic performance, high diffraction efficiency, high sensitivity, small exposure required, and stable holographic performance.

[0144] The optical device proposed by the present invention includes the holographic optical element as described above. The optical device includes but is not limited to a head-up display device (HUD), an augmented reality device (AR device, Augmented Reality), a virtual reality device (VR device, Virtual Reality), a photopolymer holographic storage disc, etc. The photopolymer holographic storage disc can be erasable and rewritable and record in real time, is suitable for storing a large amount of data, and has a very fast data transmission speed.

[0145] It can be seen from the above that the optical device proposed by the present invention, because it includes the aforementioned holographic optical element of the present invention, also has the advantages of the holographic optical element of the present invention, and the optical device has excellent and stable holographic performance.

[0146] The photopolymer holographic recording medium of the present invention is described below with reference to specific embodiments.

[0147] Example 1

[0148] In this embodiment, the photopolymer holographic recording medium 1-1 includes the following raw materials of various components in parts by weight:

[0149] The first component: 30 parts of cellulose acetate.

[0150] The second component: 25 parts of epoxy resin; the epoxy resin is bisphenol A type epoxy resin.

[0151] The third component: 39 parts of polymerizable monomers; the polymerizable monomers are 15 parts of pentabromophenyl acrylate and 24 parts of phenoxyethyl acrylate.

[0152] The fourth component: 2 parts of a photosensitive initiator combination; the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the photosensitizer new methylene blue is taken in 0.3 parts, the free radical photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is taken in 1.3 parts, and the cationic photoinitiator diaryliodonium salt is taken in 0.4 parts.

[0153] The fifth component: 0.3 parts of chain transfer agent; the chain transfer agent is mercaptoethanol.

[0154] The sixth component: 0.4 parts of catalyst; the catalyst is triethylenediamine.

[0155] The seventh component: 3 parts of additives. The additives include antioxidants and leveling agents, wherein the antioxidants are 1 part of Irganox 1010 and 0.5 parts of Irganox 168, and the leveling agent is 1.5 parts of BYK-302.

[0156] Example 2

[0157] In this embodiment, the photopolymer holographic recording medium 1-2 includes the following raw materials of various components in parts by weight:

[0158] The first component: 20 parts of cellulose acetate.

[0159] The second component: 18 parts of epoxy resin; the epoxy resin is glycerol triglycidyl ether.

[0160] The third component: 49 parts of polymerizable monomers; the polymerizable monomers are 20 parts of 2-phenoxyethyl methacrylate and 29 parts of benzyl methacrylate.

[0161] The fourth component: 2 parts of a photosensitive initiator combination; the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the photosensitizer ethyl violet is taken in 0.3 parts, the free radical photoinitiator 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl is taken in 1.5 parts and the cationic photoinitiator triarylsulfonium salt is taken in 0.2 parts.

[0162] The fifth component: 1 part of chain transfer agent; the chain transfer agent is hexanethiol.

[0163] The sixth component: 2 parts of catalyst; the catalyst is dimethylethanolamine.

[0164] The seventh component: 8 parts of additives. The additives include defoamer, leveling agent, plasticizer, ultraviolet absorber and light stabilizer, wherein defoamer BYK-085 is taken in 2 parts, leveling agent BYK-329 is taken in 2 parts, plasticizer phthalate is taken in 1 part, ultraviolet absorber 2-hydroxy-4-n-octyloxybenzophenone is taken in 2 parts, and light stabilizer 944 is taken in 1 part.

[0165] Example 3

[0166] In this embodiment, the photopolymer holographic recording medium 1-3 includes the following raw materials of various components in parts by weight:

[0167] The first component: 40 parts of cellulose acetate.

[0168] The second component: 20 parts of epoxy resin; the epoxy resin is n-butyl glycidyl ether.

[0169] The third component: 35 parts of polymerizable monomers; the polymerizable monomers are 15 parts of pentachlorophenyl methacrylate and 20 parts of bisphenol A diacrylate.

[0170] The fourth component: 2 parts of a photosensitive initiator combination; the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the photosensitizer basic yellow takes 0.3 parts, the free radical photoinitiator 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone takes 0.9 parts, and the cationic photoinitiator ferrocenium salt compound takes 0.8 parts.

[0171] The fifth component: 1 part of chain transfer agent; the chain transfer agent is 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol.

[0172] The sixth component: 1 part of catalyst; the catalyst is stannous octoate.

[0173] The seventh component: 1 part of additives. The additives include ultraviolet absorbers, light stabilizers and antioxidants, wherein the ultraviolet absorber 2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol is taken in 0.3 parts, the light stabilizer 622 is taken in 0.4 parts, and the antioxidant Irganox B900 is taken in 0.3 parts.

[0174] Example 4

[0175] In this embodiment, the photopolymer holographic recording medium 1-4 includes the following raw materials of various components in parts by weight:

[0176] The first component: 30 parts of polyvinyl alcohol.

[0177] The second component: 11 parts of epoxy resin; the epoxy resin is 1 part of glycidyl acrylate, 5 parts of glycidyl linoleate, and 5 parts of 1-benzyl-4-glycidyl piperazine.

[0178] The third component: 46 parts of polymerizable monomers; the polymerizable monomers are 26 parts of 2-naphthyl acrylate and 20 parts of 2-naphthyl methacrylate.

[0179] The fourth component: 2 parts of photosensitive initiator combination agent; the photosensitive initiator combination agent includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein 0.2 parts of brilliant green, 1 part of free radical photoinitiator 2,2-dimethoxy-phenylacetophenone, and 0.8 parts of cationic photoinitiator diaryliodonium salt are taken.

[0180] The fifth component: 2 parts of chain transfer agent; the chain transfer agent is hexanethiol.

[0181] The sixth component: 3 parts of catalyst; the catalyst is 1.3 parts of dibutyltin dilaurate.

[0182] The seventh component: 6 parts of additives. The additives include defoamer, leveling agent and plasticizer, wherein the defoamer BYK-1707 is taken in 0.4 parts, the leveling agent BYK-358 is taken in 1 parts, and the plasticizer glycerin is taken in 0.5 parts.

[0183] Example 5

[0184] In this embodiment, the photopolymer holographic recording medium 1-5 includes the following raw materials of various components in parts by weight:

[0185] The first component: 42 parts of polyvinyl alcohol.

[0186] The second component: 5 parts of epoxy resin; the epoxy resin is triglycidyl isocyanurate (S,S,S).

[0187] The third component: 50 parts of polymerizable monomers; the polymerizable monomers are 25 parts of tetrabromobisphenol A dimethacrylate and 25 parts of 2,4,6-tribromophenyl acrylate.

[0188] The fourth component: 1 part of a photosensitive initiator combination; the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the photosensitizer is eosin Y taking 0.1 part, the free radical photoinitiator is 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone taking 0.6 part, and the cationic photoinitiator is triarylsulfonium salt taking 0.3 part.

[0189] The fifth component: 0.2 parts of chain transfer agent; the chain transfer agent is mercaptoethanol.

[0190] The sixth component: 1 part of catalyst; the catalyst is N,N-bis(dimethylaminopropyl)isopropanolamine.

[0191] The seventh component: 0.8 parts of additives. The additives include a leveling agent and an antioxidant, wherein the leveling agent BYK-333 is taken in 0.2 parts and the antioxidant Irganox 1035 is taken in 0.6 parts.

[0192] Example 6

[0193] In this embodiment, the photopolymer holographic recording medium 1-6 includes the following raw materials of various components in parts by weight:

[0194] The first component: 60 parts of polyvinyl alcohol.

[0195] The second component: 20 parts of epoxy resin; the epoxy resin is 10 parts of diglycidyl hexahydrophthalate and 10 parts of glycidyl laurate.

[0196] The third component: 10 parts of polymerizable monomers; the polymerizable monomers are 5 parts of bisphenol A diacrylate and 5 parts of bisphenol A dimethacrylate.

[0197] The fourth component: 1 part of a photosensitive initiator combination; the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the photosensitizer is eosin Y taking 0.1 part, the free radical photoinitiator is 1-hydroxycyclohexyl phenyl ketone taking 0.5 part, and the cationic photoinitiator is a ferrocenium salt compound taking 0.4 part.

[0198] The fifth component: 1 part of chain transfer agent; the chain transfer agent is dodecyl mercaptan.

[0199] The sixth component: 1 part of catalyst; the catalyst is dibutyltin dilaurate.

[0200] The seventh component: additives 7 parts. The additives include plasticizers, ultraviolet absorbers, light stabilizers and antioxidants, wherein the plasticizer is 1 part of phthalate, the ultraviolet absorber 2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol 2 parts, the light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate 2 parts, and the antioxidant Irganox3114 takes 2 parts.

[0201] Example 7

[0202] In this embodiment, the photopolymer holographic recording medium 1-7 includes the following raw materials of various components in parts by weight:

[0203] The first component: a total of 60 parts of a polyol compound and a polyisocyanate compound, wherein the polyol compound is tetraethylene glycol; and the polyisocyanate compound is hexamethylene diisocyanate.

[0204] The second component: 12 parts of epoxy resin, the epoxy resin is glycidyl linoleate.

[0205] The third component: 18 parts of polymerizable monomers; the polymerizable monomers are 8 parts of styrene and 10 parts of p-chlorophenyl methacrylate.

[0206] The fourth component: 1 part of a photosensitive initiator combination; the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the photosensitizer is erythrosine, which takes 0.1 part, the free radical photoinitiator 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, which takes 0.3 part, and the cationic photoinitiator ferrocenium salt compound, which takes 0.6 part.

[0207] The fifth component: 1 part of chain transfer agent; the chain transfer agent is hexanethiol.

[0208] The sixth component: 2 parts of catalyst; the catalyst is bis(dimethylaminoethyl) ether.

[0209] The seventh component: 6 parts of additives. The additives include leveling agent, UV absorber and antioxidant, 3 parts of leveling agent BYK-329, 2 parts of UV absorber 2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, and 1 part of antioxidant Irganox B900.

[0210] Example 8

[0211] In this embodiment, the photopolymer holographic recording medium 1-8 includes the following raw materials of various components in parts by weight:

[0212] The first component: a total of 58 parts of a polyol compound and a polyisocyanate compound, wherein the polyol compound is trimethylolethane; and the polyisocyanate compound is dicyclohexylmethane diisocyanate.

[0213] The second component: 30 parts of epoxy resin, the epoxy resin is 1-benzyl-4-glycidyl ester piperazine.

[0214] The third component: 2.1 parts of polymerizable monomer; the polymerizable monomer is phenoxyethoxyethyl methacrylate.

[0215] The fourth component: 4 parts of a photosensitive initiator combination; the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the photosensitizer is 0.3 parts of rhodamine B, the free radical photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is 1.8 parts, and the cationic photoinitiator ferrocenium salt compound is 1.9 parts.

[0216] The fifth component: 0.1 parts of chain transfer agent; the chain transfer agent is hexanethiol.

[0217] The sixth component: 3 parts of catalyst; the catalyst is bis(dimethylaminoethyl) ether.

[0218] The seventh component: 2.8 parts of solvent, which is benzene.

[0219] Example 9

[0220] In this embodiment, the photopolymer holographic recording medium 1-9 includes the following raw materials of various components in parts by weight:

[0221] The first component: a total of 49 parts of a polyol compound and a polyisocyanate compound, wherein the polyol compound is triethanolamine; and the polyisocyanate compound is isophorone diisocyanate.

[0222] The second component: 13 parts of epoxy resin, the epoxy resin is glycidyl laurate.

[0223] The third component: 19 parts of polymerizable monomer; the polymerizable monomer is phenoxyethoxyethyl methacrylate.

[0224] The fourth component: 0.2 parts of a photosensitive initiator combination; the photosensitive initiator combination includes a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the photosensitizer is quinaldine red, taking 0.01 parts, the free radical photoinitiator ethyl p-dimethylaminobenzoate taking 0.09 parts, and the cationic photoinitiator diaryliodonium salt taking 0.1 parts.

[0225] The fifth component: 0.3 parts of chain transfer agent; the chain transfer agent is phenylethyl mercaptan.

[0226] The sixth component: 0.5 parts of catalyst; the catalyst is dibutyltin dilaurate.

[0227] The seventh component: 18 parts of additives. The additives include defoamers, leveling agents, plasticizers, ultraviolet absorbers, light stabilizers and antioxidants. The defoamer is BYK-1740, which is 3 parts; the leveling agent is BYK-333, which is 3 parts; the plasticizer is dimethylacetamide, which is 3 parts; the ultraviolet absorber is 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol, which is 3 parts; the light stabilizer 622 is 3 parts; the antioxidant is Irganox 1010, which is 1 part; Irganox 168 is 0.5 parts; and Irganox 1076 is 1.5 parts.

[0228] Comparative Example 1

[0229] In this embodiment, the components are substantially the same as those in Embodiment 3, except that the amount of the second component epoxy resin in Embodiment 3 is increased to 55 parts, and the polymerizable monomer is removed to obtain a common photopolymer holographic recording medium 2-1.

[0230] Comparative Example 2

[0231] In this embodiment, the components are substantially the same as those in Embodiment 7, except that the second component epoxy resin in Embodiment 3 is removed, and the amount of the third component polymerizable monomer added is increased to 30 parts, thereby obtaining a common photopolymer holographic recording medium 2-2.

[0232] Test example

[0233] The holographic performance of the grating after recording the grating on the holographic recording medium of Examples 1-9 and Comparative Examples 1-2 is tested, and the testing method comprises the following steps: During the testing, according to different photosensitive systems, different wavelengths of laser light can be selected for exposure in Examples 1-9. In the following testing method, the photosensitive system of the photopolymer holographic recording medium in Examples 1, 3, 5, and 7 is used to select the corresponding wavelength of laser light for illustration.

[0234] Grating preparation: Use solid lasers with wavelengths of 633nm (Example 1), 457nm (Example 3), and 532nm (Example 5 and Example 7) as light sources, and obtain two beams of 8mm diameter with the same light intensity after passing through a beam expander, a beam splitter, and a half-wave plate. The two beams intersect in the prepared holographic recording medium for exposure, and the light intensity is 3mW / cm 2 The detection light source is a 785nm wavelength solid 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 the photodetector, and the single grating diffraction efficiency (η) of the photopolymer holographic recording medium is calculated by formula (1).

[0235]

[0236] Where η is the diffraction efficiency, I d is the diffracted light, I t For transmitted light.

[0237] The diffraction peak shift value of the sample can be tested by UV-visible spectrometer. Figure 3 The transmittance curve of the grating prepared by using 532nm laser at 500-550nm, the greater the deviation from the preparation wavelength (532nm), the higher the shrinkage of the photopolymer.

[0238] The holographic performance tests of the photopolymer holographic recording media 1-1 to 1-9 in Examples 1-9 and the common photopolymer holographic recording media 2-1 and 2-2 in Comparative Example 1-2 are shown in Table 1 below.

[0239] Table 1 Holographic performance test table of each photopolymer holographic recording medium in Examples 1-9 and Comparative Examples 1-2

[0240]

[0241] In summary, the photopolymer holographic recording media 1-1, 1-3, 1-5, and 1-7 in Example 1, Example 3, Example 5, and Example 7 are selected to draw corresponding holographic performance graphs, and the results are as follows: Figure 1 Select the ordinary holographic recording medium 2-1 of comparative example 1 and the ordinary holographic recording medium 2-2 of comparative example 2 to draw a holographic performance diagram, and obtain Figure 2 It can be seen that the photopolymer holographic recording medium of the present invention has high photosensitivity and requires a small exposure. 2 Transmissive and reflective volume holographic gratings with diffraction efficiency greater than 95% can be recorded. In addition, for the photopolymer holographic recording medium 2-1 of comparative example 1, in which no polymerizable monomer is added to the writing monomer and only epoxy resin is present, the diffraction peak shift value is the smallest compared to the preparation wavelength (457nm), indicating that the sample has the smallest shrinkage rate; but the required exposure amount is the largest, the diffraction efficiency of the volume holographic grating is the lowest among all the test examples, the sensitivity is also the lowest, and the holographic performance is poor. The general shrinkage rate of the photopolymer holographic recording medium of the present invention can be controlled within a certain range.

[0242] Combination Figure 3 As shown in Table 1, for the photopolymer holographic recording medium 2-2 of Comparative Example 2, in which no epoxy resin is added to the writing monomer and only the polymerizable monomer is present, the diffraction peak shift value is larger than the preparation wavelength (532 nm); while the diffraction peak shift value of the photopolymer holographic recording medium 1-6 of the present invention is smaller than the preparation wavelength (532 nm).

[0243] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A photopolymer holographic recording medium, characterized in that: It comprises a writing unit, wherein the writing unit comprises: Epoxy resin; The polymerizable monomer is selected from at least one of alkenyl naphthalene compounds, alkenyl anthracene compounds, alkenyl benzene compounds, acrylic compounds, methacrylic compounds, acrylate compounds, methacrylate compounds, N-vinyl pyrrole, N-vinyl carbazole, N-vinylimidazole, N-vinyl indole, N-vinyl pyrrolidone, and trans-N-3-ynyl butenyl carbazole.

2. The photopolymer holographic recording medium according to claim 1, wherein: The epoxy resin has a refractive index greater than 1.5 and a viscosity lower than 100 mPa·s; and / or, The epoxy resin is selected from bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, hydrogenated bisphenol A epoxy resin, glycerol triglycidyl ether, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, diglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, pentanediol diglycidyl ether, glycerol triglycidyl ether, 3,4-epoxycyclohexenemethyl-3,4- Epoxy cyclohexene ester, polyethylene glycol diglycidyl ether, diglycidyl ether, diethylene glycol diglycidyl ether, benzyl glycidyl ether, phenyl glycidyl ether, furfuryl glycidyl ether, 2-biphenyl glycidyl ether, pentaerythritol glycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,4-butanediol glycidyl ether, trimethylolethane triglycidyl ether, 2-ethoxyphenyl Glycidyl ether, 1,2-cyclohexanediol diglycidyl ether, tetrabromobisphenol A epoxy resin, diglycidyl phthalate, glycidyl p-toluenesulfonate, glycidyl butyrate, glycidyl decanoate, glycidyl octanoate, glycidyl oleate, glycidyl stearate, glycidyl laurate, glycidyl acrylate, glycidyl versatate, glycidyl palmitate, glycidyl linolenate, glycidyl linoleate, triglycidyl isocyanurate , diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, glycidyl 4-tert-butylbenzoate, 1-benzyl-4-glycidyl piperazine, triglycidyl isocyanurate (S,S,S), diglycidyl 4,5-epoxytetrahydrophthalate, 4-hydroxybutyl acrylate glycidyl ether, 3-glycidylpropyl (dimethoxy)methylsilane, triglycidyl amino-meta-cresol, and triglycidyl p-aminophenol.

3. The photopolymer holographic recording medium according to claim 1, wherein: The writing monomer accounts for 10 to 60 parts by weight of the photopolymer holographic recording medium; and / or, the photopolymer holographic recording medium further includes a film-forming resin, a photosensitive initiator composition, a chain transfer agent and a catalyst, and the photopolymer holographic recording medium further includes an additive or a solvent.

4. The photopolymer holographic recording medium according to claim 3, wherein: The film-forming resin includes cellulose acetate or polyvinyl alcohol; or, The film-forming resin comprises a polyisocyanate compound and a polyol compound, wherein the polyisocyanate compound is a compound having at least two isocyanate groups, and the polyol compound is a compound having at least two hydroxyl functional groups.

5. The photopolymer holographic recording medium according to claim 3 or 4, wherein: The raw materials of each component are included in the following parts by weight: First component: 20 to 60 parts of cellulose acetate or polyvinyl alcohol; The second component: 1 to 25 parts of epoxy resin; The third component: 5 to 50 parts of polymerizable monomer; The fourth component: 0.1 to 4 parts of photosensitive initiator combination agent; The fifth component: 0.1 to 3 parts of chain transfer agent; The sixth component: 0.1 to 3 parts of catalyst; The seventh component: 0.1 to 18 parts of additives or solvents.

6. The photopolymer holographic recording medium according to claim 3 or 4, wherein: The raw materials of each component are included in the following parts by weight: The first component: 20 to 50 parts of polyol compound and 10 to 40 parts of polyisocyanate compound; The second component: 3 to 30 parts of epoxy resin; The third component: 0.1 to 47 parts of polymerizable monomer; The fourth component: 0.1 to 4 parts of photosensitive initiator combination agent; The fifth component: 0.1 to 3 parts of chain transfer agent; The sixth component: 0.1 to 3 parts of catalyst; The seventh component: 0.1 to 18 parts of additives or solvents.

7. The photopolymer holographic recording medium according to claim 3, wherein: The photosensitive initiator combination comprises a photosensitizer, a free radical photoinitiator and a cationic photoinitiator, wherein the free radical photoinitiator can activate the cationic photoinitiator, and the cationic photoinitiator can initiate the ring-opening of the epoxy resin and the polymerization of the polymerizable monomer; and / or, The chain transfer agent is a thiol compound; and / or, The catalyst is at least one of a tertiary amine catalyst or an organic metal catalyst; and / or, When the photopolymer type holographic recording medium includes additives, the additives include one or more of a defoaming agent, a leveling agent, a plasticizer, an ultraviolet absorber, a light stabilizer, and an antioxidant.

8. A method for preparing a photopolymer holographic recording medium as claimed in claim 5, characterized in that: The following steps are involved: Weigh each component of the photopolymer holographic recording medium into a container, stir thoroughly until all components are dissolved; filter using a filter membrane to obtain a mixture; apply the mixture onto a substrate, dry in a dark room at a humidity of 10% to 85% and a temperature of 20° C. to 50° C., and obtain a photopolymer holographic recording medium after the solvent evaporates.

9. A method for preparing a photopolymer holographic recording medium as claimed in claim 6, characterized in that: The following steps are involved: Weigh the components of the photopolymer holographic recording medium into a container, stir thoroughly until all the components are dissolved; filter using a filter membrane to obtain a mixture; apply the mixture to a substrate, and cure it in a dark room at a temperature of 10° C. to 50° C. to obtain a photopolymer holographic recording medium after the polyol compound and the polyisocyanate compound form a film.

10. A holographic optical element, characterized in that: The raw material of the holographic optical element comprises the photopolymer holographic recording medium according to any one of claims 1 to 7.

11. An optical device, characterized in that: Comprising the holographic optical element as claimed in claim 10.

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