(meth)acrylate monomers, methods for their preparation and use

Abstract

A (meth)acrylate monomer, its preparation method, and its application are disclosed. The general structural formulas are shown in formulas G1, G2, G3, and G4, where R1 is methyl or hydrogen. The (meth)acrylate monomers proposed in this invention have relatively small molecular size, are not prone to aggregation, have high refractive index, are liquid, have low viscosity, and exhibit good compatibility with other components.

Description

Technical Field

[0001] This invention relates to the field of holographic materials technology, and in particular to (meth)acrylate monomers, their preparation methods and applications. Background Technology

[0002] The various components used to make holographic recording media, such as photosensitive dyes, initiators, chain transfer agents, writing monomers, film-forming resins, and dehydrating agents, work together to determine the performance of the holographic recording media.

[0003] The migration rate and polymerization rate of the writing monomers jointly determine the grating formation speed. A faster migration rate than polymerization rate is required to obtain a grating with stable refractive index modulation. When the writing monomers located in the coherent bright region polymerize, the unreacted writing monomers in the coherent dark region rapidly migrate to the coherent bright region, squeezing the film-forming resin in the bright region into the coherent dark region. This makes the refractive index of the bright region close to that of the writing monomers, and the refractive index of the dark region close to that of the film-forming resin. Simultaneously, a refractive index difference between the writing monomers and the film-forming resin is necessary to form a refractive index-modulated volume holographic grating. A greater refractive index difference between the writing monomers and the film-forming resin allows the holographic recording medium to form a refractive index-modulated volume holographic grating more quickly. In existing photopolymer-based refractive index-modulated phase-type volume holographic gratings, the writing monomer viscosity needs to be low, specifically, with a kinematic viscosity below 100 mm⁻¹. 2 / s. Additionally, the writing monomer needs to have a high refractive index, specifically refractive index n > 1.6. However, writing monomers with a refractive index higher than 1.6 are usually solids or viscous liquids, in which case the kinematic viscosity of these writing monomers is higher than 200 mg / L. 2 The limit of / s restricts the amount of writing monomer added to the photopolymer, resulting in insufficient refractive index difference between the writing monomer and the film-forming resin, which affects the improvement of the holographic performance of the holographic recording medium. Summary of the Invention

[0004] In view of this, the present invention proposes a (meth)acrylate monomer, its preparation method and application, aiming to achieve a (meth)acrylate monomer with a high refractive index and in a liquid state, so as to improve the holographic optical performance of photopolymer holographic recording media containing (meth)acrylate monomers.

[0005] The first aspect of this invention provides a (meth)acrylate monomer with the general structural formulas shown in formulas G1, G2, G3 and G4:

[0006] Wherein, R1 is methyl or hydrogen.

[0007] As can be seen from the above technical solutions, the (meth)acrylate monomers proposed in the first aspect of this invention possess (meth)acrylate groups, exhibiting high refractive index and low volume shrinkage. The monomers contain multiple aromatic rings, thioheterocyclic rings, and other groups with high molar refractive index and low molar volume, resulting in an overall extremely high refractive index for the entire monomer molecule. The entire monomer structure is compact, has low viscosity, and exists in a liquid state.

[0008] The second aspect of the present invention provides a method for preparing (meth)acrylate monomers in the aforementioned examples, comprising the following steps: dissolving compound P1 in a solvent, adding hydride and stirring for a certain time, then adding compound M1 to react, removing excess solvent, and separating to obtain compound P2;

[0009] Compound P2 and an acid-binding agent were dissolved in a solvent, and compound M2 was added until the reaction was complete. Excess reactants and solvent were removed, and the (meth)acrylate monomers were obtained by separation.

[0010] The compound P1 is selected from compounds having the following structural formula:

[0011]

[0012] The compound M1 includes 2,3-dibromo-1-propanol and / or 2,3-dichloro-1-propanol;

[0013] The compound M2 is acryloyl chloride or methacryloyl chloride.

[0014] The method for preparing (meth)acrylate monomers proposed in the second aspect of this invention involves a two-step reaction to synthesize the desired (meth)acrylate monomers. The reaction conditions during the synthesis process are easily controlled. By using hydrides, hydrogen can be abstracted from the thiol group in compound P1, thereby activating compound P1. The sulfur in the thiol group of compound P1 further attacks the halogen functional group in compound M1, forming a rapid polymerization reaction between compound P1 and compound M1 to generate compound P2 with a heterosulfide ring. The hydroxyl group in compound P2 reacts with the halogen in compound M2 to finally generate a compound with (meth)acrylate groups. The molecular structure of the entire compound is stable.

[0015] The third aspect of this invention provides a photopolymer-type holographic recording medium containing (meth)acrylate monomers, comprising a writing monomer, wherein the writing monomer comprises the (meth)acrylate monomer and a polymerizable monomer.

[0016] The photopolymer holographic recording medium containing (meth)acrylate monomers proposed in the third aspect of this invention, by adding (meth)acrylate monomers and polymerizable monomers, the two components can cooperate to form a writing monomer component with a high refractive index, thereby enabling the writing monomer and the film-forming resin to have a greater refractive index difference, providing the necessary material basis for the formation of phase-type volume holographic gratings with refractive index modulation in the photopolymer holographic recording medium.

[0017] The fourth aspect of this invention provides a holographic optical element, wherein the raw material of the holographic optical element includes the photopolymer type holographic recording medium of the aforementioned examples.

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

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

[0020] The optical devices proposed in the fifth aspect of this invention, such as head-up display devices, augmented reality devices, virtual reality devices, and photopolymer holographic storage optical discs, have excellent holographic performance.

[0021] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the disclosure of the embodiments of the present invention. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 These are holographic exposure characteristic curves of photopolymer holographic recording media 5-1, 5-3, and 5-5 in Example 5;

[0024] Figure 2 This is a proportional holographic exposure characteristic curve. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0026] Photopolymer materials used for holographic recording utilize light to polymerize writing monomers, which then combine with film-forming resin to form a phase-type holographic grating with refractive index modulation to achieve holographic recording. In the coherent bright region, monomer polymerization is consumed, reducing its concentration, while in the coherent dark region, monomers hardly react. This difference in monomer concentration between the bright and dark regions causes monomers in the dark region to migrate towards the bright region. Simultaneously, the film-forming resin in the bright region is squeezed into the dark region. Ultimately, the refractive index of the bright region approaches the refractive index of the polymer, and the refractive index of the dark region approaches the refractive index of the film-forming resin, thus forming a phase-type volume holographic grating with refractive index modulation.

[0027] Improving the performance of photopolymers generally requires the film-forming resin to have a lower refractive index and the writing monomer to have a higher refractive index. However, the existing low-viscosity monomers that can be used in photopolymers typically have a refractive index below 1.60, and monomers with a refractive index above 1.60 are usually solids or viscous liquids, which limits their addition amount in photopolymers. Therefore, the refractive index difference between the writing monomer and the film-forming resin is small, usually only 0.1 to 0.2.

[0028] This invention provides a (meth)acrylate monomer as a component of a writing monomer. The (meth)acrylate monomer of this invention has a refractive index higher than 1.61, is in a liquid state, and has a kinematic viscosity lower than 100 mm. 2 / s. The present application uses liquid (meth)acrylate monomers with high refractive index and isocyanate-alcohol with low refractive index as film-forming resin to form a volume holographic grating with greater refractive index difference, thereby improving the holographic performance of the photopolymer holographic recording medium and making the photopolymer holographic recording medium highly sensitive and with high recording grating diffraction efficiency.

[0029] Where there is no conflict, the following embodiments and features can be combined with each other.

[0030] The (meth)acrylate monomers of the present invention will now be described.

[0031] According to the present invention, a (meth)acrylate monomer has the general structural formulas shown in formulas G1, G2, G3 and G4:

[0032] R1 is either methyl or hydrogen.

[0033] As can be seen from the above, the (meth)acrylate monomers proposed in this invention possess at least one (meth)acrylate group, exhibiting high refractive index and low volume shrinkage. The monomers contain multiple aromatic rings, thioheterocyclic rings, and other groups with high molar refractive index and low molar volume, as well as some sulfur atoms that inherently possess high refractive index, resulting in an overall extremely high refractive index for the monomer molecule. The entire monomer structure is compact, has low viscosity, is liquid-like, and exhibits good compatibility with other components. When used in photopolymer-based holographic recording media, it can enhance holographic performance.

[0034] In some examples, (meth)acrylate monomers are selected from monomers having the following structural formula:

[0035]

[0036] Therefore, the (meth)acrylate monomers in the above examples all have the advantages of high refractive index (refractive index higher than 1.61), small molecular structure for easy migration, low viscosity, liquid state and good compatibility with other components.

[0037] In some examples, the refractive index of the (meth)acrylate monomers is 1.61–1.67, and the kinematic viscosity is 10–100 mm. 2 / s.

[0038] The preparation method of the (meth)acrylate monomers of the present invention is described below.

[0039] The preparation method of the (meth)acrylate monomers in the foregoing examples according to the present invention includes the following steps:

[0040] Step S1: Dissolve compound P1 in a solvent, add hydride and stir for a certain time, then add compound M1 to react, remove excess solvent, and separate to obtain compound P2.

[0041] The structural formula of compound P1 in step S1 is:

[0042] Compound M1 includes 2,3-dibromo-1-propanol and / or 2,3-dichloro-1-propanol;

[0043] The structural formula of compound P2, which is formed after the reaction of compound P1 and compound M1, is as follows:

[0044]

[0045] Understandably, in step S1, by using hydrides, hydrogen can be extracted from the thiol group in compound P1, thereby activating compound P1. The S in the thiol group of compound P1 further attacks the halogen functional group in compound M1, forming a rapid polymerization reaction between compound P1 and compound M1 to generate compound P2 with a heterosulfide ring. At the same time, compound P2 has both the aromatic ring on the original compound P1 and the hydroxyl group on the original compound M1.

[0046] In some examples, the hydride includes at least one of sodium hydride or potassium hydride. That is, sodium hydride, potassium hydride, or both can be used. When adding the hydride, it can be added slowly and in multiple additions while stirring to ensure a more complete reaction and full activation of compound P1.

[0047] In some specific examples, the reaction time of compound P1 with the hydride is 0.2h to 2h, for example, it can be 0.2h, 0.5h, 0.7h, 0.8h, 1h, 1.2h, 1.5h, 1.8h or 2h, to allow compound P1 and the hydride to react fully.

[0048] In some examples, the molar ratio of compound P1, the hydride, and compound M1 is 1:(2–5):(1–2). Within this range, the reaction proceeds smoothly, the hydrogen on the thiol group of compound P1 is sufficiently abstracted by the hydride, and the reaction between compound P1 and compound M1 is relatively complete with minimal residue. For example, the molar ratio of compound P1, compound M1, and the first photoinitiator is 1:3:1, 1:2:1, 1:3:2, 1:4:2, 1:5:2, etc.

[0049] In some examples, controlling the reaction time of compounds P1 and M1 within 0.1 h to 1 h ensures that the reaction is complete while keeping the overall reaction time within a reasonable range. For example, reaction times of 0.1 h, 0.2 h, 0.3 h, 0.5 h, 0.8 h, and 1 h are used.

[0050] In some examples, the solvents used in step S1 include one or more of ethanol, petroleum ether, dichloromethane, chloroform, ethyl acetate, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide. These solvents have good compatibility with compound P1, compound M1, and the hydride; they also facilitate the control of the concentrations of the two compounds, resulting in a more homogeneous reaction system; after the reaction is complete, these solvents have good volatility, thus facilitating the removal of the solvents to obtain the desired reactant, such as compound P2, which is convenient for further processing.

[0051] Step S2: Dissolve compound P2 and the acid-binding agent in a solvent, and add compound M2 until the reaction is complete. Remove excess reactants and solvent, and separate to obtain the (meth)acrylate monomer.

[0052] The compound M2 used in step S2 is Where R1 is methyl or hydrogen, R1 is methyl methacryloyl chloride when it is methyl, and methacryloyl chloride when it is hydrogen.

[0053] Understandably, in step S2, the hydroxyl group in compound P2 can react with the halogen in compound M2 to ultimately generate a compound with (meth)acrylate groups, and the molecular structure of the entire compound is stable.

[0054] In some examples, the molar ratio of compound P2, the acid-binding agent, and compound M2 is 1:(1–2):(1–2). The use of an acid-binding agent effectively neutralizes protons in the reaction system, reduces the influence of acid on the reaction, and fixes hydrogen ions in the solution, protecting other substances from the acidic environment, thus facilitating further reaction between compound P2 and compound M2. For example, in specific examples, the molar ratio of compound P2, the acid-binding agent, and compound M2 is 1:1:1, 1:2:1, 1:1.5:1, or 1:2:2. In more specific examples, the molar ratio of compound P2, the acid-binding agent, and compound M2 can be chosen to be between 1:(1–1.5):(1–2).

[0055] In specific examples, the acid-binding agent includes at least one selected from triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, tetrabutylammonium bromide, potassium carbonate, ammonium carbonate, and sodium carbonate. The raw materials are readily available and easily separated from the final (meth)acrylate monomers.

[0056] In some examples, the reaction temperature of compound P2, the acid-binding agent, and compound M2 is controlled at 0°C, for example, using an ice bath. This helps control the reaction rate, prevents overheating which could lead to an increase in byproducts or decomposition of the target substance, thereby improving the yield and selectivity of the main reaction and reducing the volatilization of volatile substances and the degradation of unstable substances. It also facilitates the subsequent separation and purification of the target product.

[0057] In some examples, excess compound M2 in the reactants is removed by adding dilute hydrochloric acid.

[0058] In some examples, the mixture after the reaction in step S2 is washed sequentially with saturated NaCl solution, saturated NaHCO3 solution and deionized water, the organic phase is dried with anhydrous sodium sulfate, excess solvent is removed by rotary evaporation, and then separated by column chromatography to obtain the (meth)acrylate monomers of the present invention.

[0059] In some examples, the solvent includes one or more of ethanol, petroleum ether, dichloromethane, chloroform, ethyl acetate, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide, as long as it facilitates the reaction of compound P2 and compound M2 and has good compatibility with compound P2, the acid-binding agent, and compound M2. For example, in step S2, more specifically, the following solvents can be selected: dichloromethane, chloroform, and ethyl acetate.

[0060] As can be seen from the above, the method for preparing (meth)acrylate monomers proposed in this invention can synthesize the desired (meth)acrylate monomers through a two-step reaction, and the reaction conditions during the synthesis process are easy to control. By using hydrides, hydrogen can be abstracted from the thiol group in compound P1, thereby activating compound P1. The sulfur in the thiol group of compound P1 further attacks the halogen functional group in compound M1, forming a rapid polymerization reaction between compound P1 and compound M1 to generate compound P2 with a heterosulfide ring. The hydroxyl group in compound P2 reacts with the halogen in compound M2 to finally generate a compound with a (meth)acrylate group. The molecular structure of the entire compound is stable.

[0061] In the following examples, compound M1 is used as an example of 2,3-dibromo-1-propanol to illustrate the preparation method of (meth)acrylate monomers. The specific two-step reaction steps are not described in detail when compound M1 is 2,3-dichloro-1-propanol.

[0062] Therefore, the preparation method of (meth)acrylate monomers with the general structural formula G1 includes the following two reaction steps:

[0063] The first step involves the reaction of the thiol group in compound P1-1 with the halogen functional group in compound M1 to form a -SC- saturated bond, as shown below:

[0064]

[0065] The second step involves the reaction of the carbonyl group of methacryloyl chloride / acryloyl chloride with the hydroxyl group in compound P2-2 to generate a compound with a methacrylate group or acrylate group in the (meth)acrylate monomer with the structural formula G1, as shown below:

[0066]

[0067] Therefore, the preparation method of (meth)acrylate monomers with the general structural formula G2 includes the following two reaction steps:

[0068] The first step involves the reaction of the thiol group in compound P1-2 with the halogen functional group in compound M1 to form a -SC- saturated bond, as shown below:

[0069]

[0070] The second step involves the reaction of the carbonyl group of methacryloyl chloride / acryloyl chloride with the hydroxyl group in compound P2-2 to generate a compound with a methacrylate group or acrylate group in the (meth)acrylate monomer with the structural formula G2, as shown below:

[0071]

[0072] Therefore, the preparation method of (meth)acrylate monomers with the general structural formula G3 includes the following two reaction steps:

[0073] The first step involves the reaction of the thiol group in compound P1-3 with the halogen functional group in compound M1 to form a -SC- saturated bond, as shown below. At this point, the molar ratio of compound P1-3 to compound M1 is 1:2.

[0074]

[0075] The second step involves the reaction of the carbonyl group of methacryloyl chloride / acryloyl chloride with the hydroxyl group in compound P2-3 to generate a compound with a methacrylate group or acrylate group in the (meth)acrylate monomer with the structural formula G3, as shown below:

[0076]

[0077] Therefore, the preparation method of (meth)acrylate monomers with the general structural formula G4 includes the following two reaction steps:

[0078] The first step involves the reaction of the thiol group in compound P1-4 with the halogen functional group in compound M1 to form a -SC- saturated bond, as shown below:

[0079]

[0080] The second step involves the reaction of the carbonyl group of methacryloyl chloride / acryloyl chloride with the hydroxyl group in compound P2-4 to generate a compound with a methacrylate group or acrylate group in the (meth)acrylate monomer with the structural formula G3, as shown below:

[0081]

[0082] The present invention describes a photopolymer-type holographic recording medium containing (meth)acrylate monomers.

[0083] The photopolymer holographic recording medium containing (meth)acrylate monomers from the aforementioned examples, as proposed in this invention, includes a writing monomer, which comprises (meth)acrylate monomers and polymerizable monomers.

[0084] The photopolymer holographic recording medium containing (meth)acrylate monomers proposed in this invention, by adding (meth)acrylate monomers and polymerizable monomers, the two components can cooperate to form a writing monomer component with a high refractive index, thereby enabling the writing monomer and the film-forming resin to have a greater refractive index difference, providing the necessary material basis for the formation of phase-type volume holographic gratings with refractive index modulation in the photopolymer holographic recording medium.

[0085] In some examples of this invention, the writing monomer accounts for 15% to 55% of the total weight of the photopolymer-type holographic recording medium. This ensures that the writing monomer has a sufficient concentration to achieve the concentration difference between bright and dark areas after the reaction under illumination. The photopolymer-type holographic recording medium also includes a film-forming resin, a photoinitiator, a chain transfer agent, a catalyst, and additives. The film-forming resin includes compounds having multiple isocyanate reactive functional groups and polyisocyanate compounds. When the film-forming resin and the writing monomer are combined, a phase-type volume holographic grating with refractive index modulation and refractive index difference can be formed.

[0086] In some embodiments of the invention, the photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight:

[0087] First component: 15 to 40 parts of a compound having multiple isocyanate reactive functional groups. For example, it can be 15 parts, 20 parts, 30 parts, 35 parts, 40 parts, etc.

[0088] Second component: 15 to 40 parts of polyisocyanate group compound. For example, it can be 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, etc.

[0089] The third component consists of 1 to 30 parts of (meth)acrylate monomers. For example, it can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, etc.

[0090] Fourth component: 10 to 40 parts of polymerizable monomers. For example, it can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, etc.

[0091] Fifth component: 0.1 to 3 parts of photosensitizing initiator. For example, it can be 0.1, 0.2, 0.3, 0.5, 1, 1.5, 2.0, 2.5, or 3 parts.

[0092] Component 6: Chain transfer agent, 0.1 to 3 parts. For example, it 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.

[0093] Component 7: Catalyst, 0.1 to 5 parts. For example, it 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, 3.5 parts, 4 parts, 4.2 parts, 4.6 parts, 5 parts, etc.

[0094] Component 8: Additives 0.1 to 9 parts. For example, it can be 0.1 parts, 0.2 parts, 0.3 parts, 0.5 parts, 1 part, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4 parts, 5 parts, 6 parts, 6.5 parts, 7 parts, 8 parts, 9 parts, etc.

[0095] As can be seen from the above, the photopolymer holographic recording medium containing (meth)acrylate monomers proposed in this invention can achieve full synergistic effect of each component by reasonably controlling the amount of each component added. This prevents the holographic performance of the final photopolymer holographic recording medium from deteriorating due to too much or too little of a certain component, thus ensuring that the overall holographic performance of the final photopolymer holographic recording medium is better.

[0096] For example, by controlling the amount of a compound having multiple isocyanate reactive functional groups to 15 to 40 parts and the amount of a polyisocyanate group compound to 15 to 40 parts, the first and second components together form a film-forming resin with a low refractive index, thereby providing support for the other components. In some specific examples, the amount of a compound having multiple isocyanate reactive functional groups is further controlled to 20 to 35 parts, and the amount of a polyisocyanate group compound is further controlled to 20 to 35 parts.

[0097] By controlling the (meth)acrylate monomers to 1-30 parts and the polymerizable monomers to 10-40 parts, and the third and fourth components being the writing monomers, and considering that the intermolecular bonding refractive index will be higher after polymerization, the interaction of the above four components can achieve a high refractive index component and a low refractive index component with a large refractive index difference in the photopolymer holographic recording medium, forming a high refractive index difference between the film-forming resin and the writing monomer. Thus, under the action of light, the monomers in the bright area (such as the third and fourth components) polymerize and are consumed, resulting in a decrease in concentration, while the monomers in the dark area hardly react. The difference in monomer concentration between the bright and dark areas causes the high concentration of monomers in the dark area to begin migrating to the bright area, while the various components of the film-forming resin in the bright area (such as the first and second components) are squeezed into the dark area, making the refractive index of the bright area close to the refractive index of the third and fourth components, while the refractive index of the dark area close to the refractive index of the first and second components, forming a phase-type volume holographic grating with refractive index modulation. In some specific examples, the (meth)acrylate monomers are further controlled in the range of 3 to 20 parts; the polymerizable monomers are further controlled in the range of 20 to 35 parts.

[0098] For example, controlling the photoinitiator composition to 0.1 to 3 parts allows for the absorption of a suitable number of photons during exposure and controls the polymerization reaction at a certain rate, enabling the grating to form quickly and achieve high diffraction efficiency. Furthermore, it ensures that the final holographic recording medium has the required light transmittance and that the grating has a certain diffraction efficiency. In some specific examples, the photoinitiator composition is 0.3 to 2 parts.

[0099] For example, controlling the chain transfer agent to 0.1 to 3 parts allows the polymer chain length to be kept within a reasonable range and effectively prevents excessive polymerization, ensuring that the final holographic recording medium has the required optical properties and diffraction efficiency. In some specific examples, the chain transfer agent is further controlled to 0.5 to 2 parts.

[0100] For example, controlling the catalyst content to 0.1 to 5 parts can effectively increase the reaction rate of related components and the consumption rate of related components after exposure, thereby rapidly forming a concentration difference of monomers in the bright and dark areas and realizing a phase-type volume holographic grating with refractive index modulation. In some specific examples, the catalyst content is further controlled to 0.5 to 3 parts.

[0101] For example, controlling the additive to 0.1 to 9 parts, using the additive as a leveling agent, can effectively improve the uniformity of the mixture, enhance its flowability, and reasonably control costs. In some specific examples, the additive is further controlled to 0.6 to 6 parts.

[0102] In some optional examples, a photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight: Component 1 – 15 parts of a compound having multiple isocyanate reactive functional groups; Component 2 – 31 parts of a polyisocyanate group compound; Component 3 – 30 parts of (meth)acrylate monomers; Component 4 – 20 parts of polymerizable monomers; Component 5 – 1 part of a photoinitiator; Component 6 – 1 part of a chain transfer agent; Component 7 – 0.7 parts of a catalyst; and Component 8 – 1.3 parts of additives.

[0103] In some optional examples, a photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight: Component 1 – 20 parts of a compound having multiple isocyanate reactive functional groups; Component 2 – 37 parts of a polyisocyanate group compound; Component 3 – 3 parts of (meth)acrylate monomers; Component 4 – 24 parts of polymerizable monomers; Component 5 – 3 parts of a photoinitiator; Component 6 – 3 parts of a chain transfer agent; Component 7 – 3 parts of a catalyst; and Component 8 – 7 parts of additives.

[0104] In some optional examples, a photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight: Component 1 – 40 parts of a compound having multiple isocyanate reactive functional groups; Component 2 – 15 parts of a polyisocyanate group compound; Component 3 – 2 parts of (meth)acrylate monomers; Component 4 – 33 parts of polymerizable monomers; Component 5 – 1 part of a photoinitiator; Component 6 – 1 part of a chain transfer agent; Component 7 – 2 parts of a catalyst; and Component 8 – 6 parts of additives.

[0105] In some optional examples, a photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight: Component 1 – 34 parts of a compound having multiple isocyanate reactive functional groups; Component 2 – 15 parts of a polyisocyanate group compound; Component 3 – 1 part of a (meth)acrylate monomer; Component 4 – 30 parts of a polymerizable monomer; Component 5 – 3 parts of a photoinitiator; Component 6 – 3 parts of a chain transfer agent; Component 7 – 5 parts of a catalyst; and Component 8 – 9 parts of an additive.

[0106] In some optional examples, a photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight: Component 1 – 30 parts of a compound having multiple isocyanate reactive functional groups; Component 2 – 16 parts of a polyisocyanate group compound; Component 3 – 30 parts of (meth)acrylate monomers; Component 4 – 12 parts of polymerizable monomers; Component 5 – 2.9 parts of a photoinitiator combination; Component 6 – 0.1 parts of a chain transfer agent; Component 7 – 2 parts of a catalyst; and Component 8 – 7 parts of additives.

[0107] In some optional examples, a photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight: Component 1 – 33 parts of a compound having multiple isocyanate reactive functional groups; Component 2 – 18 parts of a polyisocyanate group compound; Component 3 – 35 parts of (meth)acrylate monomers; Component 4 – 11 parts of polymerizable monomers; Component 5 – 1 part of a photoinitiator; Component 6 – 1 part of a chain transfer agent; Component 7 – 0.1 parts of a catalyst; and Component 8 – 0.9 parts of an additive.

[0108] In some optional examples, a photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight: Component 1 – 25 parts of a compound having multiple isocyanate reactive functional groups; Component 2 – 30 parts of a polyisocyanate group compound; Component 3 – 22 parts of (meth)acrylate monomers; Component 4 – 13 parts of polymerizable monomers; Component 5 – 0.2 parts of a photoinitiator combination; Component 6 – 0.8 parts of a chain transfer agent; Component 7 – 3 parts of a catalyst; and Component 8 – 6 parts of additives.

[0109] In some optional examples, a photopolymer-type holographic recording medium containing (meth)acrylate monomers comprises the following components in parts by weight: Component 1 – 35 parts of a compound having multiple isocyanate reactive functional groups; Component 2 – 15 parts of a polyisocyanate group compound; Component 3 – 21 parts of (meth)acrylate monomers; Component 4 – 28.6 parts of polymerizable monomers; Component 5 – 0.1 parts of a photoinitiator; Component 6 – 0.1 parts of a chain transfer agent; Component 7 – 0.1 parts of a catalyst; and Component 8 – 0.1 parts of an additive.

[0110] In some examples of the present invention, in compounds having multiple isocyanate reactive functional groups, the isocyanate reactive functional group is a hydroxyl group. The hydroxyl group is a polar group, and the alcoholic hydroxyl group therein is easily oxidized, exhibiting high reactivity. For example, in specific examples, compounds having multiple isocyanate reactive functional groups are compounds with a refractive index less than 1.5 and containing two or more hydroxyl functional groups.

[0111] More specifically, compounds having multiple isocyanate reactive functional groups are 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 also have low refractive indices; for example, tetraethylene glycol has a refractive index of 1.46 (20°C); trimethylolethane has a refractive index of 1.5; glycerol has a refractive index of 1.474 (20°C); and triethanolamine has a refractive index of 1.482 to 1.485 (20°C).

[0112] In some examples of the present invention, the polyisocyanate compound is a compound with a refractive index of less than 1.5 and having two or more isocyanate groups.

[0113] 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)tri(hexamethylene)isocyanate, butane-1,4-diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate. These compounds also have low refractive indices: hexamethylene diisocyanate has a refractive index of 1.453; trimethylhexamethylene diisocyanate has a refractive index of 1.462; (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tri(hexamethylene)isocyanate has a refractive index of 1.472; butane-1,4-diisocyanate has a refractive index of 1.453; isophorone diisocyanate has a refractive index of 1.484; and dicyclohexylmethane diisocyanate has a refractive index of 1.496 (25°C).

[0114] In some examples of the present invention, the polymerizable monomer is selected from at least one of alkenylnaphthalene compounds, alkenylanthracene compounds, alkenylbenzene compounds, acrylic compounds, methacrylic acid compounds, acrylate compounds, methacrylate compounds, N-vinylpyrrole, N-vinylcarbazole, N-vinylimidazol, N-vinylindole, N-vinylpyrrolidone, and trans-N-3-yntynebutenylcarbazole.

[0115] In a specific example, the alkenylnaphthalene compound is selected from at least one of 1-vinylnaphthalene and 2-vinylnaphthalene.

[0116] In a specific example, the alkenyl anthracene compound is selected from at least one of 2-vinylanthracene and 9-vinylanthracene.

[0117] 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.

[0118] In specific examples, methacrylic acid compounds include at least one of methacrylic acid and its derivatives.

[0119] In specific examples, 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-tris(4-chlorophenyl)propionyl]oxy}propane-3,1-diyl)oxyethane-2,1-diyl]diacrylate.

[0120] In specific examples, the methacrylate compounds are 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.

[0121] In some examples of this invention, the photoinitiator combination includes a photosensitizer and a photoinitiator. The photosensitizer, when combined with the photoinitiator, can form a visible light initiation system, adaptable to lasers of different wavelengths. Under irradiation with light within a specific wavelength range, the photosensitizer in the photoinitiation system is correspondingly photoactivated, absorbs light energy, and transfers the light energy to the photoinitiator. This allows the photoinitiator to be activated under light radiation in a wider wavelength range, generating free radicals with initiation functions. These photoinitiated free radicals can initiate monomer polymerization to construct holographic gratings, improve the photosensitivity of photopolymer-type holographic recording media, and broaden the range of selectable light sources.

[0122] Therefore, it is understandable that in other examples, when the present invention uses a photoinitiator with an appropriate wavelength, a photosensitizer may not be added.

[0123] When the photoinitiator combination contains both a photosensitizer and a photoinitiator, the mass ratio of the photosensitizer to the photoinitiator is further (0.001–1):(0.1–3). By controlling the mass ratio of the photosensitizer to the photoinitiator within the above range, the concentration of the photosensitizer can be effectively controlled, ensuring that the number of absorbed photons during holographic exposure is controlled within a suitable range, the polymerization reaction rate is controlled within a reasonable range, and the grating formation rate is controlled within a certain range, thus guaranteeing the transmittance of the photopolymer holographic recording medium and obtaining excellent diffraction efficiency. In more specific examples, the mass of the photosensitizer is 1 / 10 to 1 / 3 of the mass of the photoinitiator, such as 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, or 1 / 3, etc.

[0124] In this invention, different broadband responses can be achieved by controlling the type of photosensitizer. For example, the photosensitizer is a dye that has high electron transfer efficiency under light irradiation.

[0125] In a specific example, 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 benzylidene cycloalkane ketone compounds.

[0126] More specifically, the photosensitizers are selected from methylene blue (maximum absorption wavelength 666 nm), thionine (absorption wavelength 602.5 nm), basic yellow (absorption wavelength 412 nm), pinacyanin chloride, rhodamine 6G (absorption wavelength 400 nm–700 nm), gallium cyanide, ethyl violet (absorption wavelength 596 nm), Victoria Blue R (maximum absorption wavelength 615 nm), celestite blue (absorption wavelength 630–640 nm), methylene blue (maximum absorption wavelength 662 nm), basic orange, and darozyme (maximum absorption wavelength 502 nm). One or more of the following: pyrrole red Y (with strong absorption wavelengths of 235nm, 267nm, 336nm, and 515nm), basic red 29, quinaldinium red (maximum absorption wavelength of 528nm), crystal violet (absorption wavelength of 588nm–592nm), ethyl violet (maximum absorption wavelength of 596nm), brilliant green (maximum absorption wavelength of 630nm), azurite A (maximum absorption wavelength of 633nm), crystal violet cyanine (maximum absorption wavelength of 579nm), malachite green cyanine, and eosin (absorption wavelength of 510nm–518nm).

[0127] In a specific example, the photoinitiator is selected from at least one of aromatic ketone compounds, benzoin and its derivatives, benzoyl ketal, acylphosphine oxide, ammonium arylboronate, chromium salts, aryl diazonium salts, onium salts, and organometallic compounds. Other photoinitiators with similar functions may also be used, and this invention is not limited thereto.

[0128] More specifically, the photoinitiator is selected from benzophenone (absorption wavelengths 210 nm, 255 nm), alkylbenzophenone (290 nm–360 nm), 4,4'-bis(dimethylamino)benzophenone, anthrone (299 nm–366 nm), halogenated benzophenone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide (absorption wavelengths 350 nm–400 nm), diacylphosphine oxide, phenyl dihydroxyacetate, camphorquinone (absorption wavelength 400 nm), etc. One or more of the following photoinitiators are selected: α-aminoalkylphenyl ketone (absorption wavelength 380nm-430nm), α,α-dialkoxyacetophenone, α-hydroxyalkylphenyl ketone (absorption wavelength 320nm-380nm), tetrabutylammonium triphenylhexylborate, tetrabutylammonium tri-(3-fluorophenyl)hexylborate, tetrabutylammonium tri-(3-chloro-4-methylphenyl)hexylborate, ferrocene compounds, iodonium salts, thiodonium salts, and hexaaryldiimidazole. When these photoinitiators are irradiated with light within the corresponding wavelength range, they can be rapidly activated and generate active free radicals, thereby initiating polymerization reactions between the components of the photopolymer-type holographic recording medium, achieving monomer concentration differences between bright and dark areas. Alternatively, when the photosensitizer in combination absorbs light within the corresponding wavelength range, it transfers heat to the photoinitiator, thereby activating the photoinitiator.

[0129] In some examples of this invention, the chain transfer agent is a thiol compound.

[0130] In specific examples, the chain transfer agent includes one or more of the following: dodecyl mercaptoethanol, mercaptoethanol, hexamethylene mercaptoethanol, phenylethyl mercaptoethanol, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, and 4-methyl-4H-1,2,4-triazole-3-thiol.

[0131] In some examples of this invention, the catalyst is a tertiary amine catalyst or an organometallic catalyst.

[0132] In a specific example, the catalyst is selected from at least one of the following: triethylenediamine, bis(dimethylaminoethyl) ether, dimethylethanolamine, 2-(2-dimethylamino-ethoxy)ethanol, trimethylhydroxyethylpropanediamine, N,N-bis(dimethylaminopropyl)isopropanolamine, dibutyltin dilaurate, stannous octoate, potassium carboxylate catalysts, and bismuth carboxylate catalysts. The catalyst is not limited to the types listed above; any catalyst capable of catalyzing the polymerization reaction of the aforementioned components under light irradiation is acceptable. Those skilled in the art should understand that these all fall within the scope of protection of this invention.

[0133] In some examples of the present invention, the additives include one or more of defoamers, leveling agents, and dehydrating agents.

[0134] In a specific example, the defoamer is a silicone defoamer and / or a silicone-free polymeric defoamer, and the defoamer accounts for less than or equal to 3% of the weight of the photopolymeric holographic recording medium. The defoamer can reduce the surface tension of the liquid and remove foam, thereby improving the flowability of the mixture of components.

[0135] More specifically, one can choose, for example, BYK-011, BYK-012, BYK-014, BYK-023, BYK-051N, BYK-085, BYK-1610, BYK-1707, BYK-1740, and BYK-1760 manufactured by BYK Corporation, or DC65 and AFE-7820 manufactured by Dow Corning Corporation, or any mixture of these defoamers in any proportion. The BYK series of defoamers have excellent defoaming performance, good compatibility with other components, and good dispersibility; among them, BYK-011, BYK-012, BYK-014, and BYK-051N are silicone-free polymeric defoamers. DC65 is a water-based ink that dries quickly, provides good printing results, and is not easily peeled off. AFE-7820 has highly efficient defoaming performance.

[0136] In a specific example, the leveling agent is a silicone surface additive, and the leveling agent accounts for less than or equal to 3% by weight of the photopolymer-type holographic recording medium. Examples include BYK-302, BYK-306, BYK-307, BYK-327, BYK-329, BYK-333, BYK-356, BYK-358, BYK-378, BYK-3455, BYK-3566, or any mixture of these surface additives manufactured by BYK. The BYK series of leveling agents exhibits excellent leveling properties.

[0137] In specific examples, the dehydrating agents are selected from methylbenzenesulfonyl isocyanate, triethyl orthoformate, CUWR-WB20 dehydrating agent from Guangzhou Yourun Synthetic Materials Co., Ltd., ALT-201 dehydrating agent from Anxiang Elite Chemical Co., Ltd., and PCCI dehydrating agent from Shanghai Luer Chemical Trading Co., Ltd., etc.

[0138] In some examples, the dehydrating agent constitutes less than or equal to 3% of the weight of the photopolymer holographic recording medium. The dehydrating agent removes excess water during the reaction, allowing the components to mix better and preventing stratification.

[0139] The application of the photopolymer holographic recording medium containing (meth)acrylate monomers of the present invention is described below.

[0140] The holographic optical element proposed in this invention uses photopolymer-type holographic recording media from the aforementioned examples as raw materials. This holographic optical element includes, but is not limited to, volume holographic gratings.

[0141] As can be seen from the above, the holographic optical element proposed in this invention, since it includes the aforementioned photopolymer holographic recording medium of this invention, also has the advantages of the photopolymer holographic recording medium of this invention, namely high diffraction efficiency, high sensitivity, and small required exposure amount.

[0142] The optical device proposed in this invention includes the holographic optical elements described above. This optical device includes, but is not limited to, head-up displays (HUDs), augmented reality (AR) devices, virtual reality (VR) devices, and photopolymer holographic storage optical discs. Photopolymer holographic storage optical discs can be erasable and rewritable, and can record in real time, making them suitable for storing large amounts of data with very fast data transfer speeds.

[0143] As can be seen from the above, the optical device proposed in this invention, since it includes the aforementioned holographic optical element of this invention, also has the advantages of the holographic optical element of this invention. The optical device has excellent holographic performance, clear optical image, and can store a large amount of data.

[0144] The following describes the (meth)acrylate monomers, the preparation method of (meth)acrylate monomers, and the photopolymer holographic recording medium containing (meth)acrylate monomers of the present invention with reference to specific embodiments.

[0145] Example 1

[0146] In this embodiment, the general structural formula of the (meth)acrylate monomer is G1:

[0147] The preparation method of (meth)acrylate monomers with structural formula G1 includes the following steps:

[0148] Step S1: Compound P1-1 was dissolved in ethanol, stirred until homogeneous, and sodium hydride was slowly added. The mixture was stirred for 1 hour, followed by the addition of compound M1 and a reaction time of 0.5 hours. Excess solvent was removed by rotary evaporation, and the target product, compound P2-1, was obtained by column chromatography. The reaction equation is as follows:

[0149]

[0150] Step S2: Compound P2-1 and the acid-binding agent triethylamine were dissolved in ethyl acetate and stirred for 10 min. Compound M2 (methacryloyl chloride / acryloyl chloride) was added until the reaction was complete. Dilute hydrochloric acid was added to remove excess compound M2. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution, and deionized water. The organic phase was dried over anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. The resulting product was then separated by column chromatography to obtain the (meth)acrylate monomer G1 of this invention. The reaction equation is as follows:

[0151]

[0152] Therefore, when the R1 of compound M2 is different, monomers G1 with different structures (including G1-a and G1-b) are generated in this application, as shown in Table 1 below.

[0153] The characterization data are as follows:

[0154] G1-a: 1 H NMR (400MHz, CDCl3) δ7.37–7.26 (m, 4H), 5.77 (dq, J = 1.9, 0.9Hz, 1H), 5.64

[0155] (dq,J=1.8,0.8Hz,1H),4.47–4.35(m,2H),3.95(p,J=7.7Hz,1H),3.50(d,J=7.5Hz,1H),3.00(d,J=7.5Hz,1H),1.94(t,J=0.9Hz,3H).

[0156] G1-b: 1 H NMR (400MHz, CDCl3) δ7.37–7.25(m,4H),6.16–6.05(m,1H),5.91(dd,J=

[0157] 17.7, 2.7Hz, 1H), 5.84 (dd, J = 17.4, 2.7Hz, 1H), 4.36 (d, J = 7.8Hz, 2H), 3.92 (p, J = 7.6Hz, 1H), 3.50 (d, J = 7.5Hz, 1H), 3.00 (d, J = 7.5Hz, 1H).

[0158] Table 1. M2 corresponding to G1 with different structures and performance parameters

[0159] Example reactant M2 Target single unit G1 G1 refractive index <![CDATA[Kinematic viscosity (mm 2 / s)]]> 1-1 Methacryl chloride G1-a 1.62 11 1-2 Acrylyl chloride G1-b 1.63 13

[0160] Example 2

[0161] In this embodiment, the general structural formula of the (meth)acrylate monomer is G2:

[0162] The preparation method of (meth)acrylate monomers with the structural formula G2 includes the following steps:

[0163] Step S1: Compound P1-2 was dissolved in ethyl acetate, stirred until homogeneous, and sodium hydride was slowly added. The mixture was stirred for 1 hour, followed by the addition of compound M1 and reaction for 0.5 hours. Excess solvent was removed by rotary evaporation, and the target product, compound P2-2, was obtained by column chromatography. The reaction equation is as follows:

[0164]

[0165] Step S2: Compound P2-2 and the acid-binding agent pyridine were dissolved in dichloromethane and stirred for 10 min. Compound M2 (methacryloyl chloride / acryloyl chloride) was added until the reaction was complete. Dilute hydrochloric acid was added to remove excess compound M2. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution, and deionized water. The organic phase was dried over anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. The final product was obtained by column chromatography to obtain the (meth)acrylate monomer G2 of this invention. The reaction equation is as follows:

[0166]

[0167] Therefore, when the R1 of compound M2 is different, monomers G2 with different structures (including G2-a and G2-b) are generated in this application, as shown in Table 2 below.

[0168] The characterization data are as follows:

[0169] G2-a: 1 H NMR (400MHz, CDCl3) δ7.24 (d, J = 7.7Hz, 1H), 7.15–7.09 (m, 1H), 7.13–7.06

[0170] (m,1H),5.79(dq,J=1.7,0.9Hz,1H),5.65(dq,J=1.8,0.8Hz,1H),4.47–4.35(m,2H),3.95(p,J =7.7Hz,1H),3.51(d,J=7.5Hz,1H),3.01(d,J=7.5Hz,1H),2.31(s,3H),1.94(t,J=0.9Hz,3H).

[0171] G2-b: 1 H NMR (400MHz, CDCl3) δ7.21 (d, J = 7.5Hz, 1H), 7.15–7.08 (m, 2H), 6.15–6.04

[0172] (m,1H),5.88(ddd,J=26.9,17.5,2.7Hz,2H),4.36(d,J=7.8Hz,2H),3.92(p,J=7.6Hz,1H),3.29(dd,J=17.6,7.5Hz,2H),2.30(s,3H).

[0173] Table 2. M2 corresponding to G2 with different structures and performance parameters

[0174]

[0175] Example 3

[0176] In this embodiment, the general structural formula of the (meth)acrylate monomer is G3:

[0177] The preparation method of (meth)acrylate monomers with the structural formula G3 includes the following steps:

[0178] Step S1: Compound P1-3 was dissolved in petroleum ether, stirred until homogeneous, and sodium hydride was slowly added. The mixture was stirred for 1 hour, followed by the addition of compound M1 and reaction for 0.5 hours. Excess solvent was removed by rotary evaporation, and the target product, compound P2-3, was obtained by column chromatography. In this step, the molar ratio of compound P1-3 to compound M1 was 1:2. The reaction equation is as follows:

[0179]

[0180] Step S2: Compound P2-3 and the acid-binding agent pyridine were dissolved in chloroform and stirred for 10 min. Compound M2 (methacryloyl chloride / acryloyl chloride) was added until the reaction was complete. Dilute hydrochloric acid was added to remove excess compound M2. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution, and deionized water. The organic phase was dried over anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. The resulting product was then separated by column chromatography to obtain the (meth)acrylate monomer G3 of this invention. In this step, the molar ratio of compound P2-3 to compound M2 was 1:2. The reaction equation is as follows:

[0181]

[0182] Therefore, when the R1 of compound M2 is different, monomers G3 with different structures (including G3-a and G3-b) are generated in this application, as shown in Table 3 below.

[0183] The characterization data are as follows:

[0184] G3-a: 1H NMR (400MHz, CDCl3) δ7.25 (s, 1H), 7.19 (s, 1H), 5.80 (q, J = 1.6Hz, 1H), 5.76

[0185] (dq,J=1.8,0.9Hz,1H),5.61(ddt,J=14.9,2.7,1.2Hz,2H),4.34(d,J=7.7Hz,4H),3.99(p,J= 7.7Hz,2H),3.35(d,J=7.5Hz,2H),3.23(d,J=7.7Hz,2H),1.94(d,J=2.9Hz,2H),1.94(s,4H).

[0186] G3-b: 1 H NMR (400MHz, CDCl3) δ7.25(s,1H),7.19(s,1H),6.14–6.04(m,2H),5.95–5.87(m,2H),5.85(dt,J=14.7,2.7Hz,2H ), 4.37 (dd, J = 10.6, 7.7 Hz, 2H), 4.32 ( dd, J = 10.6, 7.9 Hz, 2H), 3.97 ( p, J = 7.6 Hz, 2H), 3.25 ( dd, J = 12.3, 7.7 Hz, 4H).

[0187] Table 3. M2 corresponding to G3 with different structures and performance parameters

[0188]

[0189] Example 4

[0190] In this embodiment, the general structural formula of the (meth)acrylate monomer is G4:

[0191] The preparation method of (meth)acrylate monomers with structural formula G4 includes the following steps:

[0192] Step S1: Compound P1-4 was dissolved in petroleum ether, stirred until homogeneous, and sodium hydride was slowly added. The mixture was stirred for 1 hour, followed by the addition of compound M1 and a reaction time of 0.5 hours. Excess solvent was removed by rotary evaporation, and the target product, compound P2-4, was obtained by column chromatography. The reaction equation is as follows:

[0193]

[0194] Step S2: Compound P2-4 and potassium carbonate (an acid-binding agent) were dissolved in acetonitrile and stirred for 10 min. Compound M2 (methacryloyl chloride / acryloyl chloride) was added until the reaction was complete. Dilute hydrochloric acid was added to remove excess compound M2. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution, and deionized water. The organic phase was dried over anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. The final product was obtained by column chromatography to obtain the (meth)acrylate monomer G4 of this invention. The reaction equation is as follows:

[0195]

[0196] Therefore, when the R1 of compound M2 is different, monomers G4 with different structures (including G4-a and G4-b) are generated in this application, as shown in Table 4 below.

[0197] The characterization data are as follows:

[0198] G4-a: 1 H NMR (400MHz, CDCl3) δ7.29 (d, J = 1.7Hz, 1H), 7.21 (d, J = 1.8Hz, 1H), 5.76

[0199] (dq,J=1.7,0.8Hz,1H),5.64(dq,J=1.7,0.9Hz,1H),4.47–4.35(m,2H),3.93(p,J=7.7Hz,1H),3.39(dd,J=15.6,7.6Hz,2H),1.94(t,J=0.9Hz,3H).

[0200] G4-b: 1 H NMR (400MHz, CDCl3) δ7.27 (dd, J=13.2, 1.6Hz, 2H), 6.15–6.05 (m, 1H), 5.91

[0201] (dd,J=17.8,2.7Hz,1H),5.84(dd,J=17.4,2.7Hz,1H),4.40–4.30(m,2H),3.91(p,J=7.7Hz,1H),3.39(d,J=7.5Hz,1H),3.30(d,J=7.5Hz,1H).

[0202] Table 4. M2 corresponding to G4 with different structures and performance parameters.

[0203]

[0204] The solvents and acid-binding agents in Examples 1-4 are for illustrative purposes only and should not be construed as limiting the scope of this application. Solvents may be one or more of ethanol, petroleum ether, dichloromethane, chloroform, ethyl acetate, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide. Acid-binding agents include at least one of triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, tetrabutylammonium bromide, potassium carbonate, ammonium carbonate, and sodium carbonate. Those skilled in the art should understand that these should all be within the scope of protection of this invention.

[0205] Example 5

[0206] Photopolymer holographic recording media 5-1 to 5-8 containing (meth)acrylate monomers from Examples 1-4 are used: The specific components of photopolymer holographic recording media 5-1 to 5-8 are shown in Table 5 below.

[0207] Table 5 shows the components of each photopolymer-type holographic recording medium containing (meth)acrylate monomers from each embodiment.

[0208]

[0209]

[0210] In this embodiment, the selection of each component may also be other components listed above. These embodiments should not be construed as limiting the scope of protection of the present invention.

[0211] Comparative Example

[0212] The composition is roughly the same as that of the photopolymer holographic recording medium 5-1 in Example 5. The difference is that the (meth)acrylate monomer G1-a of the photopolymer holographic recording medium 5-1 is removed, so that the number of (meth)acrylate monomers becomes 0 parts, while the polymerizable monomer 2-chlorostyrene is increased to 27 parts, so as to obtain a common photopolymer holographic recording medium.

[0213] Test case

[0214] The performance of the photopolymer holographic recording media 5-1 to 5-8 containing (meth)acrylate monomers in Examples 5 and the conventional photopolymer holographic recording media of the comparative examples were tested, and the results are shown in Table 6. During the tests, different wavelengths of laser light were selected for exposure of each holographic recording medium in Example 5, depending on the photosensitive system, with an exposure intensity of 3 mW / cm². 2 .

[0215] Using the photopolymer holographic recording media 5-1 containing (meth)acrylate monomers, photopolymer holographic recording media 5-3 containing (meth)acrylate monomers, and photopolymer holographic recording media 5-5 containing (meth)acrylate monomers from Example 5, corresponding holographic performance diagrams were plotted to obtain... Figure 1 .

[0216] Specifically, for the three holographic recording media 5-1, 5-3, and 5-5, solid-state lasers with wavelengths of 633nm, 457nm, and 532nm were used as light sources, respectively. After passing through a beam expander, beam splitter, and half-wave plate, two beams of equal intensity and 8mm diameter were obtained. The two beams were then exposed within the prepared holographic recording medium at an intensity of 3mW / cm². 2 The detection light source uses a 785nm wavelength solid-state laser that does not react with the recording medium. The detection light is incident on the exposure area from the Bragg angle. The transmitted light and diffracted light are monitored in real time by a photodetector. The single grating diffraction efficiency (η) and photosensitivity (S) of the photopolymer holographic recording medium are calculated by formulas (1) to (3).

[0217]

[0218] In the formula, η is the diffraction efficiency, η max For the highest diffraction efficiency, I d For diffracted light, I t S represents transmitted light, S represents photosensitivity, E represents exposure energy, and ΔE represents the exposure energy required to achieve the highest diffraction efficiency.

[0219] like Figure 1 As shown, the final measured diffraction efficiency of the photopolymer holographic recording medium of this invention is greater than 95%, and the exposure dose is less than 20 mJ / cm². 2 Sensitivity greater than 100cm 2 / mJ.

[0220] And such Figure 2 As shown, a conventional photopolymer holographic recording medium was exposed at a wavelength of 633 nm and an exposure intensity of 3 mW / cm². 2 The diffraction efficiency of the ordinary photopolymer holographic recording medium in the comparative example was found to be less than 50%, requiring an exposure dose greater than 100 mJ / cm². 2 The sensitivity is low.

[0221] The holographic performance tests of the photopolymer holographic recording media 5-1 to 5-8 in Example 5 and the ordinary photopolymer holographic recording media of the comparative example are shown in Table 6 below.

[0222] Table 6. Holographic performance test table of each photopolymer holographic recording medium in Example 5 and Comparative Examples.

[0223]

[0224] In summary, for reference Figure 1 , Figure 2 As shown in Table 6, the diffraction efficiency and sensitivity of the photopolymer-type holographic recording medium in the embodiments of the present invention are significantly higher than those of the comparative examples, and the required exposure amount is much smaller. The kinematic viscosity of the (meth)acrylate monomers in Examples 1-2 and Example 4 of the present invention is less than 20 mm². 2 / s, the kinematic viscosity of the (meth)acrylate monomers in Example 3 of the present invention is less than 100 mm. 2 The viscosity is low, and it is liquid. Furthermore, the refractive index of the (meth)acrylate monomers in Examples 1-4 of this invention is between 1.61 and 1.67, which is high. It can be seen that the (meth)acrylate monomers of this invention can be added in a high amount to the photopolymer, thereby effectively improving the refractive index of the writing monomer and further improving the refractive index difference between the writing monomer and the film-forming resin. This significantly improves the holographic performance of the photopolymer holographic recording medium containing the (meth)acrylate monomers of this invention.

[0225] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A (meth)acrylate monomer, characterized by, The structural general formula is shown as formula G1, G2, G3 and G4: ; wherein R1 is methyl or hydrogen.

2. The (meth)acrylate monomer according to claim 1, wherein The (meth) acrylic ester monomer is selected from monomers with the following structural formula: 。 3. A method for producing the (meth)acrylate monomer according to claim 1 or 2, characterized by, The method comprises the following steps: dissolving compound P1 in a solvent, adding a hydride and stirring for a certain time, then adding compound M1 for reaction, removing excess solvent, and separating to obtain compound P2; Compound P2 is dissolved with an acid binding agent in a solvent, and compound M2 is added until the reaction is complete, excess reactants are removed, and the solvent is removed, and the (meth) acrylic ester monomer is separated. The compound P1 is selected from compounds with the following structural formula: ； The compound M1 is selected from at least one of 2,3-dibromo-1-propanol or 2,3-dichloro-1-propanol; The hydride is selected from at least one of sodium hydride or potassium hydride; The compound M2 is acryloyl chloride or methacryloyl chloride.

4. The method for preparing the (meth) acrylic ester monomer according to claim 3, wherein: The stirring reaction time of the compound P1 and the hydride is 0.2h-2h; The molar ratio of the compound P1, the hydride and the compound M1 is 1:(2-5):(1-2); The reaction time of the compound P1 and the compound M1 is 0.1h-1h.

5. The method for preparing the (meth) acrylic ester monomer according to claim 3, wherein: The molar ratio of the compound P2, the acid binding agent and the compound M2 is 1:(1-2):(1-2); The reaction temperature of the compound P2, the acid binding agent and the compound M2 is controlled at 0℃; The solvent is selected from at least one of ethanol, petroleum ether, dichloromethane, trichloromethane, ethyl acetate, tetrahydrofuran, acetonitrile, N,N-dimethylformamide or dimethyl sulfoxide; The acid binding agent is selected from at least one of triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, tetrabutylammonium bromide, potassium carbonate, ammonium carbonate and sodium carbonate.

6. A photopolymer type holographic recording medium containing the (meth)acrylate monomer according to claim 1 or 2, characterized by, The writing monomer comprises the (meth) acrylic ester monomer and a polymerizable monomer.

7. The photopolymer-type holographic recording medium as described in claim 6, characterized in that, The weight percentage of the writing monomer in the entire photopolymer type holographic recording medium is 15%-55%; The photopolymer type holographic recording medium further comprises a film-forming resin, a photosensitive initiation combination agent, a chain transfer agent, a catalyst and an additive, and the film-forming resin comprises a compound with multiple isocyanate reactive functional groups and a polyisocyanate-based compound.

8. The photopolymer-type holographic recording medium as described in claim 7, characterized in that, Each component comprises the following weight parts: The first component: a compound with multiple isocyanate reactive functional groups, 15-40 parts; The second component: a polyisocyanate-based compound, 15-40 parts; The third component: a (meth) acrylic ester monomer, 1-30 parts; The fourth component: a polymerizable monomer, 10-40 parts; The fifth component: a photosensitive initiation combination agent, 0.1-3 parts; The sixth component: a chain transfer agent, 0.1-3 parts; The seventh component: a catalyst, 0.1-5 parts; The eighth component: an additive, 0.1-9 parts.

9. The photopolymer-type holographic recording medium as described in claim 7 or 8, characterized in that, In the compound with multiple isocyanate reactive functional groups, the isocyanate reactive functional group is a hydroxyl group. The compound having multiple isocyanate-reactive functional groups is selected from at least one of tetraglycol, trimethylolethane, glycerol, triethanolamine, polyester polyol having a molecular weight of 200-2000, polycarbonate polyol, and polyether polyol; The polyisocyanate-based compound is a compound having two or more isocyanate groups; The polymerizable monomer is selected from at least one of alkenyl naphthalene compound, alkenyl anthracene compound, alkenyl benzene compound, acrylic acid compound, methacrylic acid compound, acrylate compound, methacrylate compound, N-vinyl pyrrole, N-vinyl carbazole, N-vinyl imidazole, N-vinyl indole, N-vinyl pyrrolidone, and trans-N-3-alkynyl butenyl carbazole; The photosensitive initiation combination agent comprises a photosensitizer and a photoinitiator; a mass ratio of the photosensitizer to the photoinitiator is (0.001-1):(0.1-3); and an absorption wavelength of the photosensitizer and an absorption wavelength of the photoinitiator in the photosensitive initiation combination agent are different; The chain transfer agent is a thiol compound; The catalyst is a tertiary amine catalyst or an organic metal catalyst; The additive is selected from one or more of defoaming agent, leveling agent, and water removal agent.

10. A holographic optical element, characterized by The raw material of the holographic optical element comprises the photopolymer type holographic recording medium according to any one of claims 6-9.

11. An optical device, characterized by The holographic optical element comprises the holographic optical element according to claim 10.

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