Holographic polymer dispersed liquid crystal composition, holographic grating and method of preparation

Abstract

The scheme discloses a yellowing-resistant holographic polymer dispersed liquid crystal composition, a holographic grating and a preparation method, simultaneously introduces a yellowing-resistant acrylate monomer containing siloxane and a specific type of yellowing-resistant additive, the bond energy of a siloxane bond (Si-O-Si) of the yellowing-resistant acrylate monomer containing siloxane is high, is more resistant to ultraviolet light degradation than common carbon-carbon bonds and carbon-oxygen bonds, can enhance the overall stability of a polymer network, can reduce the surface energy of the polymer, increase the hydrophobicity and improve the flexibility, is beneficial to subsequent mass production, can also provide better action sites for the yellowing-resistant additive, the yellowing-resistant additive can effectively absorb the invading ultraviolet photons, convert the ultraviolet photons into harmless heat energy, quench free radicals and interrupt the chain growth of photo-oxidation reaction, the yellowing-resistant additive and the yellowing-resistant acrylate monomer containing siloxane synergistically act to provide internal and external double protection for the composite material, and the yellowing-resistant performance of the composite material is greatly improved.

Description

Technical Field

[0001] This solution belongs to the field of optical materials technology, specifically involving a yellowing-resistant holographic polymer dispersed liquid crystal composition, a holographic grating, and a preparation method. Background Technology

[0002] Holographic polymer-dispersed liquid crystal (H-PDLC) is an advanced photonic material prepared using holographic photopolymerization-induced phase separation technology. The basic preparation process involves sandwiching a pre-prepared mixture (typically containing photopolymerizable monomers, nematic liquid crystal, photoinitiator, and other additives) between two transparent substrates, followed by interference exposure using two or more coherent laser beams. In the bright and dark fringe regions of the interference pattern, the photoinitiator generates a concentration gradient, initiating differential polymerization of the monomers. In the bright fringe regions, the monomers rapidly polymerize to form polymer-rich areas, simultaneously displacing and enriching liquid crystal molecules in the dark fringe regions, thus forming a periodic alternating layered structure of polymer / liquid crystal microdroplets, i.e., a bulk phase grating.

[0003] This periodic structure endows H-PDLC with unique optical properties: its refractive index modulation effect gives it extremely high diffraction efficiency at specific wavelengths (Brag wavelengths). Based on this principle, H-PDLC technology has developed rapidly in recent years and has been widely used in many cutting-edge fields such as next-generation head-mounted displays (HMDs), augmented reality (AR) / virtual reality (VR) glasses, head-up displays (HUDs), optical storage, tunable filters, and optical switches. Especially in the AR / VR field, H-PDLC gratings are regarded as the core material for fabricating thin, high-transmittance, and high-diffraction-efficiency holographic waveguide devices.

[0004] In existing H-PDLC technology systems, to achieve excellent optical performance (such as high refractive index modulation, high diffraction efficiency, and low driving voltage), highly reactive acrylate monomers and corresponding high-efficiency photoinitiator systems are typically required in the formulation. These material components undergo polymerization reactions under ultraviolet (UV) or visible light irradiation of specific wavelengths, thereby achieving grating formation. However, this has also led to a significant and urgent technical defect in the long-term industrialization of H-PDLC technology, particularly in the consumer electronics field: poor resistance to yellowing, resulting in irreversible degradation of its optical performance and image display quality. Specifically, the defects of existing technologies are mainly reflected in the following aspects.

[0005] The inherent chemical instability of the material: Acrylic monomers and low molecular weight oligomers widely used in existing H-PDLC formulations are prone to photo-oxidation when exposed to oxygen, humidity, and especially high-energy ultraviolet / blue light for extended periods. This reaction generates chromophores (such as carbonyl groups and conjugated double bonds), causing the material to gradually change from transparent to pale yellow or even deep yellow. This intrinsic yellowing phenomenon directly leads to a decrease in the overall light transmittance and color shift of the device, severely impacting the realism and immersive experience of "seeing the world through optical light" required by AR / VR devices.

[0006] Residue and decomposition of photoinitiators and their byproducts: To achieve rapid polymerization and deep curing, current technologies often require the use of high concentrations of photoinitiators (PIs). Many highly efficient radical photoinitiators (such as Irgacure 184, 651, etc.) leave molecular fragments (such as benzoyl groups, alkyl radicals, etc.) in the polymer network after completing their initiation mission. These residues are chemically reactive and readily continue to react under subsequent light and heat conditions, becoming one of the main causes of long-term yellowing of materials. Furthermore, some initiators themselves produce yellowish byproducts during decomposition.

[0007] Yellowing has a direct negative impact on optical performance. First, it reduces diffraction efficiency: Yellowing means increased absorption of specific wavelengths of light (especially blue light). This not only causes overall light energy loss but also alters the refractive index matching between the grating and liquid crystal regions, significantly reducing the diffraction efficiency of the Bragg grating and darkening the exit pupil image. Second, it causes color distortion: Yellowed materials absorb short-wavelength blue light much more than long-wavelength red light, leading to a spectral imbalance in transmitted or diffracted light, resulting in severe color shift. The displayed image will appear yellowish, with decreased saturation and poor color reproduction, failing to achieve true color display and severely damaging the user experience. Third, it reduces contrast and increases haze: Yellowing is usually accompanied by deterioration in material homogeneity, potentially increasing the number of scattering centers, increasing device haze, raising background noise, and ultimately reducing the contrast of the displayed image. Fourth, it affects reliability and lifespan: Consumer electronics require components to maintain stable performance after long-term use. The poor resistance to yellowing of H-PDLC devices means that their optical performance will continue to decline with the use time (ambient light aging) and the length of operation (aging of the device's own light source), failing to meet the stringent requirements of product lifespan and reliability, becoming a bottleneck restricting their large-scale commercial application.

[0008] In summary, existing H-PDLC technology suffers from a fundamental drawback due to the inherent chemical properties of its material system: poor resistance to yellowing. This defect directly leads to a series of problems such as image degradation, color distortion, and efficiency degradation, severely hindering the further application of H-PDLC in high-end display devices, especially next-generation AR / VR devices. Therefore, developing a novel H-PDLC material system with high resistance to yellowing and the ability to maintain excellent and stable optical performance over a long period has become an urgent technological breakthrough in this field. Summary of the Invention

[0009] This solution aims to overcome at least one defect in the prior art and provide a holographic polymer-dispersed liquid crystal composition that is resistant to yellowing and can maintain excellent and stable optical performance over a long period of time.

[0010] To solve the above-mentioned technical problems, the following technical solution is adopted: In the first aspect, a yellowing-resistant holographic polymer-dispersed liquid crystal composition is proposed. By weight, the composition comprises 0.5-2 parts initiator, 2-5 parts co-initiator, 15-30 parts siloxane-containing yellowing-resistant acrylate monomer, 10-20 parts primary acrylate monomer, 5-15 parts secondary acrylate monomer, 5-10 parts solvent, 30-45 parts liquid crystal, and 1-3 parts yellowing-resistant additive. The siloxane-containing yellowing-resistant acrylate monomer is selected from one or more of acryloyloxytrimethylsilane, acryloyloxy-modified polysiloxane (R-8303), mono-terminated methacryloyloxypolysiloxane (MAST40), methacryloyloxypropyl di-terminated polydimethylsiloxane, acryloyloxypropyl cage-like polysilsesquioxane (Acrylo POSS), and methacryloyloxypropyl cage-like silsesquioxane (MA-POSS). The yellowing-resistant additive is selected from Irganox 1010, Irganox 1076, Irganox B215, and Irganox... One or more of 245, Irganox 1135, and Irganox 1035.

[0011] This composition simultaneously introduces siloxane-containing, yellowing-resistant acrylate monomers and specific types of yellowing-resistant additives. The siloxane bonds (Si-O-Si) of the siloxane-containing, yellowing-resistant acrylate monomers have high bond energies, making them more resistant to UV degradation than common carbon-carbon and carbon-oxygen bonds. This enhances the overall stability of the polymer network, reduces polymer surface energy, increases hydrophobicity, and improves flexibility, facilitating subsequent mass production. It also provides better activation sites for the yellowing-resistant additives, which effectively absorb intruding UV photons, converting them into harmless heat energy. These additives can quench free radicals and interrupt the chain reaction of photo-oxidation. The synergistic effect of these two components provides dual protection for the composite material, significantly improving its yellowing resistance. Furthermore, the yellowing-resistant components selected in this composition, at effective concentrations, exhibit good compatibility with liquid crystals and do not significantly affect the phase separation process, ensuring that the final holographic grating has high diffraction efficiency and low scattering loss. In addition, the formulation of this composition, due to its reduced polymer surface energy, is compatible with inkjet processes and is easily industrialized.

[0012] Preferably, the first acrylate monomer is selected from one or more of the following: isobornyl methacrylate, adamantane acrylate, adamantane methacrylate, isobornyl acrylate, cyclohexyl acrylate, 3,4-epoxycyclohexyl methyl acrylate, dicyclopentyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, lauryl acrylate, myristyl acrylate, cetearyl acrylate, behenyl acrylate, octadecyl acrylate, and lauryl methacrylate.

[0013] Preferably, the second acrylate monomer is selected from one or more of ethylene glycol dimethacrylate, ethoxylated bisphenol A dimethacrylate, 1,3-butanediol dimethacrylate, tricyclodecanediethanol diacrylate, tripropylene glycol dimethacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate.

[0014] Preferably, the liquid crystal is selected from one or more of E7, E48, BL087, BL038, TL213, MLC6882, and K15.

[0015] Preferably, the initiator is selected from one of the following: Bengal rose red, diiodofluorescein, methylene blue, TPO, rhodamine 6G, 3,3'-carbonylbis(7-diethylaminocoumarin), and initiator 184.

[0016] Preferably, the co-initiator is selected from benzoyl peroxide and N-phenylglycine.

[0017] Preferably, the solvent is selected from one or more of acetone, xylene, n-hexane, propylene glycol methyl ether, propylene glycol methyl ether acetate, N-vinylpyrrolidone, chloroform, tetrahydrofuran, and toluene.

[0018] Secondly, a yellowing-resistant holographic grating is proposed. This grating is prepared from the aforementioned yellowing-resistant holographic polymer dispersed liquid crystal composition, and therefore exhibits excellent yellowing resistance.

[0019] Thirdly, a method for fabricating the aforementioned yellowing-resistant holographic grating is proposed. This method includes the following steps: S1. Mix all components of the composition thoroughly; S2. Pour the mixed composition into the liquid crystal cell; S3. Place the composition filled into the liquid crystal cell in a dark room and let it stand. S4. Expose the composition filled into the liquid crystal cell in the interference light field of a dual-beam light source.

[0020] Preferably, the anti-yellowing additive and solvent in the composition are first mixed evenly by magnetic stirring, and then mixed evenly with other components in the composition by ultrasonic dispersion equipment.

[0021] Preferably, the thickness of the liquid crystal cell is 5±1μm.

[0022] Preferably, the composition is left to stand in a dark room for 1 to 2 hours.

[0023] Preferably, the included angle between the two beam light sources is 35~60°.

[0024] Preferably, the illumination power of the dual-beam light source is 5±1mW / cm². 2 .

[0025] Preferably, the exposure time of the composition in the interference light field is 1 to 5 minutes.

[0026] Fourthly, a waveguide sheet is proposed. This waveguide sheet contains the aforementioned anti-yellowing holographic grating and has excellent anti-yellowing properties.

[0027] Compared with existing technologies, this solution offers the following advantages: It simultaneously introduces siloxane-containing, yellowing-resistant acrylate monomers and specific types of yellowing-resistant additives. The siloxane bonds (Si-O-Si) of the siloxane-containing, yellowing-resistant acrylate monomers have high bond energies, making them more resistant to UV degradation than common carbon-carbon and carbon-oxygen bonds. This enhances the overall stability of the polymer network, reduces polymer surface energy, increases hydrophobicity, and improves flexibility, facilitating subsequent mass production. It also provides better activation sites for the yellowing-resistant additives, which effectively absorb intruding UV photons, converting them into harmless heat energy. These additives can quench free radicals and interrupt the chain reaction of photo-oxidation. The synergistic effect of these two components provides dual protection for the composite material, significantly improving its yellowing resistance. Furthermore, the selected yellowing-resistant component, at its effective concentration, exhibits good compatibility with liquid crystals and does not significantly affect the phase separation process, ensuring that the final holographic grating has high diffraction efficiency and low scattering loss. In addition, the composition formulation, by reducing polymer surface energy, is compatible with inkjet processes, making it easy to industrialize. Detailed Implementation

[0028] To enable those skilled in the art to better understand this solution, the following detailed description is provided in conjunction with specific embodiments. Unless otherwise specified, the process methods used in the embodiments are conventional methods; and unless otherwise specified, the materials used are commercially available.

[0029]

[0030] Example 1 The holographic polymer-dispersed liquid crystal composition of this embodiment comprises, by weight parts: 3 parts Irganox 1010, 10 parts N-vinylpyrrolidone, 2 parts Bengal rose red, 5 parts N-phenylglycine, 15 parts acryloyloxy-modified polysiloxane, 20 parts cyclohexyl acrylate, 15 parts trimethylolpropane triacrylate, and 30 parts K15.

[0031] Irganox 1010 from the above composition was added to N-vinylpyrrolidone and mixed thoroughly with magnetic stirring at room temperature to obtain a clear solution. The remaining components of the above composition and the obtained clear solution were placed in an ultrasonic instrument and ultrasonically mixed at 60°C for 30 minutes to obtain a mixture. The obtained mixture was poured into an empty liquid crystal cell with a thickness of 5 μm under vacuum conditions and allowed to stand in a dark room for 60 minutes. After standing, an irradiation was performed using a dual-beam irradiation with an angle of 60° and a power of 5 mW / cm². 2 A dual-beam light source was used to interfere with the mixture in the liquid crystal cell for 5 minutes to obtain a holographic grating.

[0032] Example 2 The holographic polymer-dispersed liquid crystal composition of this embodiment comprises, by weight parts: 1 part Irganox 1076, 7 parts propylene glycol methyl ether acetate, 2 parts rhodamine 6G, 5 parts benzoyl peroxide, 28 parts acryloyloxypropyl cage polysilsesquioxane, 10 parts adamantane acrylate, 7 parts tripropylene glycol dimethacrylate, and 40 parts E7.

[0033] Irganox 1076 from the above composition was added to propylene glycol methyl ether acetate and mixed thoroughly with magnetic stirring at room temperature to obtain a clear solution. The remaining components of the above composition and the obtained clear solution were placed in an ultrasonic instrument and ultrasonically mixed at 60°C for 30 minutes to obtain a mixture. The obtained mixture was poured into an empty liquid crystal cell with a thickness of 5 μm under vacuum conditions and allowed to stand in a dark room for 60 minutes. After standing, an irradiation was performed using a dual-beam irradiation with an angle of 60° and a power of 5 mW / cm². 2 A dual-beam light source was used to interfere with the mixture in the liquid crystal cell for 5 minutes to obtain a holographic grating.

[0034] Example 3 The holographic polymer-dispersed liquid crystal composition of this embodiment comprises, by weight parts: 2 parts Irganox 1035, 5 parts toluene, 0.5 parts 3,3'-carbonylbis(7-diethylaminocoumarin), 2 parts N-phenylglycine, 30 parts methacryloyloxypropyl di-terminated polydimethylsiloxane, 10.5 parts isobornyl methacrylate, 5 parts ethylene glycol dimethacrylate, and 45 parts TL213.

[0035] Irganox 1035 from the above composition was added to toluene and mixed thoroughly with magnetic stirring at room temperature to obtain a clear solution. The remaining components of the above composition and the obtained clear solution were placed in an ultrasonic instrument and ultrasonically mixed at 60°C for 30 minutes to obtain a mixture. The obtained mixture was poured into an empty liquid crystal cell with a thickness of 5 μm under vacuum conditions and allowed to stand in a dark room for 60 minutes. After standing, an irradiation was performed using a dual-beam irradiation with an angle of 60° and a power of 5 mW / cm². 2 A dual-beam light source was used to interfere with the mixture in the liquid crystal cell for 5 minutes to obtain a holographic grating.

[0036] Example 4 The holographic polymer-dispersed liquid crystal composition of this embodiment comprises, by weight parts: 1.5 parts Irganox B215, 8 parts n-hexane, 1 part diiodofluorescein, 4 parts benzoyl peroxide, 20 parts acryloyloxytrimethylsilane, 15 parts 3,4-epoxycyclohexyl methyl acrylate, 12 parts ethoxylated bisphenol A dimethacrylate, and 38.5 parts BL087.

[0037] Irganox B215 from the above composition was added to n-hexane and mixed thoroughly with magnetic stirring at room temperature to obtain a clear solution. The remaining components of the above composition and the obtained clear solution were placed in an ultrasonic instrument and ultrasonically mixed at 60°C for 30 minutes to obtain a mixture. The obtained mixture was poured into an empty liquid crystal cell with a thickness of 5 μm under vacuum conditions and allowed to stand in a dark room for 60 minutes. After standing, an irradiation was performed using a dual-beam irradiation with an angle of 60° and a power of 5 mW / cm². 2 A dual-beam light source was used to interfere with the mixture in the liquid crystal cell for 5 minutes to obtain a holographic grating.

[0038] Example 5 The holographic polymer-dispersed liquid crystal composition of this embodiment comprises, by weight, 2.5 parts Irganox 1135, 6 parts chloroform, 1.5 parts initiator 184, 3 parts N-phenylglycine, 25 parts methacryloyloxypropyl cage-like silsesquioxane, 18 parts dicyclopentyl acrylate, 9 parts 1,3-butanediol dimethacrylate, and 35 parts MLC6882.

[0039] Irganox 1135 from the above composition was added to chloroform and mixed thoroughly with magnetic stirring at room temperature to obtain a clear solution. The remaining components of the above composition and the obtained clear solution were placed in an ultrasonic instrument and ultrasonically mixed at 60°C for 30 minutes to obtain a mixture. The obtained mixture was poured into an empty liquid crystal cell with a thickness of 5 μm under vacuum conditions and allowed to stand in a dark room for 60 minutes. After standing, an irradiation was performed using a dual-beam irradiation with an angle of 60° and a power of 5 mW / cm². 2 A dual-beam light source was used to interfere with the mixture in the liquid crystal cell for 5 minutes to obtain a holographic grating.

[0040] Comparative Example 1 The holographic polymer-dispersed liquid crystal composition of this comparative example comprises, by weight, 3 parts Irganox 1010, 10 parts N-vinylpyrrolidone, 2 parts Bengal rose red, 5 parts N-phenylglycine, 20 parts cyclohexyl acrylate, 15 parts trimethylolpropane triacrylate, and 30 parts K15.

[0041] Irganox 1010 from the above composition was added to N-vinylpyrrolidone and mixed thoroughly with magnetic stirring at room temperature to obtain a clear solution. The remaining components of the above composition and the obtained clear solution were placed in an ultrasonic instrument and ultrasonically mixed at 60°C for 30 minutes to obtain a mixture. The obtained mixture was poured into an empty liquid crystal cell with a thickness of 5 μm under vacuum conditions and allowed to stand in a dark room for 60 minutes. After standing, an irradiation was performed using a dual-beam irradiation with an angle of 60° and a power of 5 mW / cm². 2A dual-beam light source was used to interfere with the mixture in the liquid crystal cell for 5 minutes to obtain a holographic grating.

[0042] Comparative Example 2 The holographic polymer-dispersed liquid crystal composition of this comparative example comprises, by weight parts: 10 parts N-vinylpyrrolidone, 2 parts Bengal rose red, 5 parts N-phenylglycine, 15 parts acryloyloxy-modified polysiloxane, 20 parts cyclohexyl acrylate, 15 parts trimethylolpropane triacrylate, and 30 parts K15.

[0043] All components of the above composition were placed in an ultrasonic instrument and ultrasonically mixed at 60°C for 30 minutes to obtain a homogeneous mixture. The resulting mixture was then poured into an empty liquid crystal cell with a thickness of 5 μm under vacuum conditions and allowed to stand in a dark chamber for 60 minutes. After standing, an irradiation was performed using a dual-beam irradiation system with an angle of 60° and a power of 5 mW / cm². 2 A dual-beam light source was used to interfere with the mixture in the liquid crystal cell for 5 minutes to obtain a holographic grating.

[0044] Comparative Example 3 The holographic polymer-dispersed liquid crystal composition of this comparative example comprises, by weight parts: 3 parts Irganox 1010, 10 parts N-vinylpyrrolidone, 2 parts Bengal rose red, 5 parts N-phenylglycine, 10 parts acryloyloxy-modified polysiloxane, 20 parts cyclohexyl acrylate, 15 parts trimethylolpropane triacrylate, and 30 parts K15.

[0045] Irganox 1010 from the above composition was added to N-vinylpyrrolidone and mixed thoroughly with magnetic stirring at room temperature to obtain a clear solution. The remaining components of the above composition and the obtained clear solution were placed in an ultrasonic instrument and ultrasonically mixed at 60°C for 30 minutes to obtain a mixture. The obtained mixture was poured into an empty liquid crystal cell with a thickness of 5 μm under vacuum conditions and allowed to stand in a dark room for 60 minutes. After standing, an irradiation was performed using a dual-beam irradiation with an angle of 60° and a power of 5 mW / cm². 2 A dual-beam light source was used to interfere with the mixture in the liquid crystal cell for 5 minutes to obtain a holographic grating.

[0046] The holographic grating samples obtained from the above embodiments and comparative examples were divided into two groups. One group underwent thermo-oxidative aging tests, and the other group underwent ultraviolet aging tests.

[0047] Thermo-oxidative aging test: The holographic grating sample was placed in an oven and baked at 80°C for 200 hours.

[0048] UV aging test: Using a UVA-340 lamp, continuous irradiation was carried out for 24 hours at 25℃ and 0.76 W / m²@340nm.

[0049] Before and after aging, the diffraction efficiency of each holographic grating sample was tested using a grating diffraction efficiency meter. The haze of each holographic grating sample was tested using a haze meter at 23±2℃ according to GB2410-2008 "Test Methods for Transparent Plastics Transmittance and Haze". The CIE LAB b values ​​of the samples before and after aging were determined using a spectrophotometer, referring to ASTM D2244 standard, and the Δb values ​​were calculated. The results are shown in the table below.

[0050]

[0051] As shown in the table above, adding appropriate amounts of siloxane-containing yellowing-resistant acrylate monomers and yellowing-resistant additives has virtually no impact on the diffraction efficiency and haze of the material, while significantly improving the yellowing resistance. Moreover, both siloxane-containing yellowing-resistant acrylate monomers and yellowing-resistant additives are indispensable; only by introducing both simultaneously can the yellowing resistance be significantly improved. Insufficient addition of siloxane-containing yellowing-resistant acrylate monomers is also detrimental to improving the yellowing resistance.

[0052] Obviously, the above embodiments of this solution are merely examples for clearly illustrating this solution, and are not intended to limit the implementation of this solution. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this solution should be included within the scope of protection of the claims of this solution.

Claims

1. A yellowing-resistant holographic polymer-dispersed liquid crystal composition, characterized in that, The composition, by weight, comprises 0.5-2 parts initiator, 2-5 parts co-initiator, 15-30 parts siloxane-containing yellowing-resistant acrylate monomer, 10-20 parts first acrylate monomer, 5-15 parts second acrylate monomer, 5-10 parts solvent, 30-45 parts liquid crystal, and 1-3 parts yellowing-resistant additive, wherein the siloxane-containing yellowing-resistant acrylate monomer is selected from one or more of acryloyloxytrimethylsilane, acryloyloxy-modified polysiloxane, mono-terminated methacryloyloxypolysiloxane, methacryloyloxypropyl di-terminated polydimethylsiloxane, acryloyloxypropyl cage-like polysilsesquioxane, and methacryloyloxypropyl cage-like silsesquioxane, and the yellowing-resistant additive is selected from one or more of Irganox 1010, Irganox 1076, Irganox B215, Irganox 245, Irganox 1135, and Irganox 1035.

2. The yellowing-resistant holographic polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The first acrylate monomer is selected from one or more of the following: isoborneol methacrylate, adamantane acrylate, adamantane methacrylate, isoborneol acrylate, cyclohexyl acrylate, 3,4-epoxycyclohexyl methyl acrylate, dicyclopentyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, lauryl acrylate, myristyl acrylate, cetearyl acrylate, behenyl acrylate, octadecyl acrylate, and lauryl methacrylate.

3. The yellowing-resistant holographic polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The second acrylate monomer is selected from one or more of ethylene glycol dimethacrylate, ethoxylated bisphenol A dimethacrylate, 1,3-butanediol dimethacrylate, tricyclodecanediethanol dimethacrylate, tripropylene glycol dimethacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate.

4. The yellowing-resistant holographic polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The liquid crystal is selected from one or more of E7, E48, BL087, BL038, TL213, MLC6882, and K15.

5. The yellowing-resistant holographic polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The initiator is selected from one of the following: Bengal rose red, diiodofluorescein, methylene blue, TPO, rhodamine 6G, 3,3'-carbonylbis(7-diethylaminocoumarin), and initiator 184.

6. The yellowing-resistant holographic polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The co-initiator is selected from benzoyl peroxide and N-phenylglycine.

7. The yellowing-resistant holographic polymer-dispersed liquid crystal composition according to claim 1, characterized in that, The solvent is selected from one or more of acetone, xylene, n-hexane, propylene glycol methyl ether, propylene glycol methyl ether acetate, N-vinylpyrrolidone, chloroform, tetrahydrofuran, and toluene.

8. A yellowing-resistant holographic grating, characterized in that, The grating is prepared from the yellowing-resistant holographic polymer dispersed liquid crystal composition according to any one of claims 1 to 7.

9. A method for preparing a yellowing-resistant holographic grating as described in claim 8, characterized in that, The method includes the following steps: S1. Mix all components of the composition thoroughly; S2. Pour the mixed composition into the liquid crystal cell; S3. Place the composition filled into the liquid crystal cell in a dark room and let it stand. S4. Expose the composition filled into the liquid crystal cell in the interference light field of a dual-beam light source.

10. The method for preparing the yellowing-resistant holographic grating according to claim 9, characterized in that, The anti-yellowing additive and solvent in the composition are first mixed evenly by magnetic stirring, and then mixed evenly with other components in the composition using an ultrasonic dispersion device; and / or The thickness of the liquid crystal cell is 5±1μm; and / or The composition is allowed to stand in a dark room for 1-2 hours; and / or The included angle of the dual-beam light source is 35~60°; and / or The illumination power of the dual-beam light source is 5±1mW / cm². 2 ; and / or The exposure time of the composition in the interference light field is 1 to 5 minutes.

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