A solid optical material and a preparation method thereof

Abstract

The present invention relates to a solid optical material and a preparation method thereof, in particular to a photochromic solid optical material, which can be used for spatial static three-dimensional imaging. The material includes salicylaldehyde aniline, methyl methacrylate, 4-vinylbenzocyclobutene, (Z)-3-hexenyl-3-boronic acid catechol ester and an initiator, and its optical transparency and imaging stability are improved by optimizing the curing process. The preparation method of the solid optical material includes material mixing, thermal polymerization, stepwise curing and post-treatment processes. Experimental results show that the material has high light transmittance and photochromic properties and can be used for high-precision three-dimensional imaging.

Description

Technical Field

[0001] The present invention relates to the field of optical functional materials, and particularly to a solid optical material and a preparation method thereof. Background Art

[0002] With the development of technology, the demand for information visualization has been increasing day by day. Especially in the fields of medical imaging, aerospace, virtual reality (VR), augmented reality (AR), etc., three-dimensional (3D) display technology has become an important research direction. Currently, common 3D display technologies mainly include stereoscopic display, holographic display, and volumetric three-dimensional display, etc.

[0003] Among them, volumetric three-dimensional display has an important development prospect in future display technologies due to its characteristics of unrestricted viewing angle and strong imaging realism. However, there are still many limitations in the existing volumetric three-dimensional display materials, mainly including:

[0004] Existing photochromic materials are difficult to meet the requirements of 3D imaging: Most traditional photochromic materials are in the form of liquid solutions or powders, such as organic dyes (Spiropyran, Diarylethene), metal complexes ( ), etc. These materials are prone to diffusion in the liquid or gas phase and it is difficult to stably maintain the 3D imaging effect; while solid photochromic materials are usually opaque or have a low light transmittance and are not suitable for high-resolution optical imaging.

[0005] The selection of transparent optical materials is limited: Currently, most of the transparent materials used in 3D optical storage and volumetric three-dimensional imaging are inorganic glasses (such as quartz glass, silicate glass) or polymer-based materials (such as PMMA, polycarbonate). However, inorganic glass materials have high costs and great processing difficulties, and existing polymer materials are prone to degradation or aging at high temperatures, affecting the stability of optical properties. Therefore, it is necessary to develop a new type of optical material that not only has a high light transmittance but also can stably carry photochromic components.

[0006] Photochromic materials are a class of intelligent materials that can change color under specific light conditions and are mainly applied in the fields of optical anti-counterfeiting, sensing, display, etc. In the field of 3D imaging, photochromic materials can form a stable optical contrast at specific positions in space by controlling the light conditions, thereby constructing a 3D stereoscopic image.

[0007] However, the application of traditional photochromic materials in volumetric three-dimensional display is restricted by the following: slow color change response speed, affecting the dynamic display effect; low transparency, affecting the light penetration ability and imaging clarity. Summary of the Invention

[0008] To overcome at least one of the technical problems in the above-mentioned background art, the present invention provides a method for preparing a solid optical material. The solid optical material prepared by this method can play an important role in the fields of optical three-dimensional display, information encryption, holographic anti-counterfeiting, etc., and has broad application prospects.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A solid optical material, in parts by mass, its composition includes:

[0011] Salicylaldehyde anilide: 0.01 - 0.1 part;

[0012] Methyl methacrylate: 100 parts;

[0013] 4-Vinylbenzocyclobutene: 0.3 - 0.8 part;

[0014] (Z)-3-Hexenyl-3-boronic acid catechol ester (CAS: 37490-28-1): 0.08 - 0.2 part;

[0015] Initiator: 0.1 - 3 parts.

[0016] According to some embodiments of the present invention, the initiator is selected from at least one of azobisisobutyronitrile (AIBN), azobisisoheptonitrile (AIHN), benzoyl peroxide (BPO), lauroyl peroxide, and cumene hydroperoxide.

[0017] A method for preparing a solid optical material, including the following steps:

[0018] 1) Material mixing: In parts by mass, disperse 0.01 - 0.1 part of salicylaldehyde anilide uniformly in 100 parts of methyl methacrylate; successively add 0.3 - 0.8 part of 4-vinylbenzocyclobutene and 0.08 - 0.2 part of (Z)-3-hexenyl-3-boronic acid catechol ester; add 0.1 - 3 parts of initiator, and stir for 10 - 30 minutes until completely dissolved;

[0019] 2) Thermal polymerization reaction: Heat up to the reaction temperature and maintain it for 0.5 - 3 hours to cause a free radical polymerization reaction in the system, and the reaction solution thickens;

[0020] 3) Curing treatment: Adopt programmed temperature rise curing, heat in a water bath, gradually increase the temperature, reduce internal stress, and enhance the mechanical strength and optical uniformity of the material;

[0021] 4) Post-treatment: Adopt cutting, grinding, and splicing processes to improve the surface finish of the material and enhance the optical transparency.

[0022] According to some embodiments of the present invention, the stirring speed in the material mixing step is 300 - 500 rpm.

[0023] According to some embodiments of the present invention, the reaction temperature in the thermal polymerization reaction step is 50 - 100 °C.

[0024] According to some embodiments of the present invention, in the curing treatment step, the programmed temperature rise curing step:

[0025] Primary curing: Constant temperature curing for 18 - 24 hours at 45 - 60 °C;

[0026] Secondary curing: Raise the temperature to 60 - 80 °C and maintain for 6 - 12 hours;

[0027] Final curing: Raise the temperature to 80 - 100 °C and maintain for 1 - 2 hours.

[0028] Advantageous effects of this method on solid optical materials:

[0029] Improve light transmittance: The formed cross - linked network inhibits the occurrence of polymer phase separation, makes the internal structure of the material more uniform, and reduces the occurrence of light scattering. At the same time, the dynamic bond rearrangement of (Z)-3 - hexenyl - 3 - boronic acid catechol ester also helps to reduce internal defects and stress concentration, further reducing light scattering, thereby improving the light transmittance of the material in the visible light region, making the material have better optical transparency and realizing high - quality three - dimensional imaging.

[0030] Regulate refractive index: The benzene ring structure in 4 - vinylbenzocyclobutene and the borate group of (Z)-3 - hexenyl - 3 - boronic acid catechol ester have relatively high refractive indices. Their introduction can adjust the overall refractive index of the material to meet the requirements of different optical applications for refractive index and achieve precise regulation of refractive index.

[0031] Reduce birefringence: The dynamic bond rearrangement of (Z)-3 - hexenyl - 3 - boronic acid catechol ester makes the orientation of molecular chains more random and uniform, reduces the orientation difference of molecular chains, thereby reducing the birefringence phenomenon of the material, improving the consistency of the optical properties of the material, and improving the three - dimensional imaging resolution.

[0032] Improve optical response speed: Using salicylideneaniline as a photochromic molecule, its molecular structure undergoes a proton transfer reaction under ultraviolet light irradiation. Control the content of salicylideneaniline to ensure fast and uniform color change response. Detailed implementation mode

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Example 1

[0035] 1) Material mixing

[0036] Take 0.05 g of salicylaldehyde anilide and add it to 100 g of methyl methacrylate, and stir evenly.

[0037] Sequentially add 0.5 g of 4-vinylbenzocyclobutene and 0.15 g of (Z)-3-hexenyl-3-boronic acid catechol ester.

[0038] Add 1.5 g of azobisisobutyronitrile (AIBN) as an initiator.

[0039] Stir for 25 minutes at a stirring speed of 400 rpm until the solution is completely mixed evenly.

[0040] 2) Thermal polymerization reaction

[0041] Gradually heat up to 80°C and maintain for 2.5 hours. A free radical polymerization reaction occurs in the system, and the reaction solution thickens and becomes in a uniform viscous state.

[0042] 3) Curing treatment (programmed temperature curing, water bath heating)

[0043] Primary curing: Constant temperature curing for 20 hours at 45°C;

[0044] Secondary curing: Heat up to 70°C and maintain for 10 hours;

[0045] Final curing: Heat up to 90°C and maintain for 1.5 hours, and the material curing is completed.

[0046] 4) Post-treatment

[0047] Use a precision cutting device to cut the cured material into a 3×3×3 cm transparent optical sheet;

[0048] Use a polishing machine to polish the surface to reduce light scattering and improve the light transmittance.

[0049] Example 2

[0050] 1) Material mixing

[0051] Take 0.02 g of salicylaldehyde anilide and add it to 100 g of methyl methacrylate, and stir evenly.

[0052] Add 0.3 g of 4-vinylbenzocyclobutene and 0.08 g of (Z)-3-hexenyl-3-boronic acid catechol ester in sequence.

[0053] Add 2.5 g of benzoyl peroxide (BPO) as an initiator.

[0054] Stir for 30 minutes at a stirring speed of 500 rpm to ensure the solution is homogeneous.

[0055] 2) Thermal polymerization reaction

[0056] Gradually heat up to 70°C and maintain for 3 hours to gradually thicken the reaction system and form a pre-cured state.

[0057] 3) Curing treatment (programmed temperature curing, water bath heating)

[0058] Primary curing: Constant temperature curing for 18 hours at 50°C;

[0059] Secondary curing: Heat up to 60°C and maintain for 8 hours;

[0060] Final curing: Heat up to 80°C and maintain for 2 hours to complete the curing of the material.

[0061] 4) Post-treatment

[0062] Cut into 5×5×1 cm transparent optical sheets using a laser cutting machine;

[0063] Perform surface fine treatment using a nanoscale polishing process.

[0064] Example 3

[0065] 1) Material mixing

[0066] Take 0.08 g of salicylaldehyde anilide and add it to 100 g of methyl methacrylate, and stir evenly.

[0067] Add 0.7 g of 4-vinylbenzocyclobutene and 0.2 g of (Z)-3-hexenyl-3-boronic acid catechol ester in sequence.

[0068] Add 0.8 g of lauroyl peroxide as an initiator.

[0069] Stir for 20 minutes at a stirring speed of 350 rpm to ensure uniform mixing.

[0070] 2) Thermal polymerization reaction

[0071] Gradually heat up to 90 °C and maintain for 1 hour to gradually form a network structure of the polymer and increase the viscosity.

[0072] 3) Curing treatment (programmed temperature curing, water bath heating)

[0073] Primary curing: Constant temperature curing for 22 hours at 55 °C;

[0074] Secondary curing: Heat up to 75 °C and maintain for 6 hours;

[0075] Final curing: Heat up to 100 °C and maintain for 1 hour to complete the curing of the material.

[0076] 4) Post-treatment

[0077] Use precision laser cutting to make a 2×2×2 cm optical device;

[0078] Use high-precision mechanical polishing to improve the optical uniformity.

[0079] Example 4

[0080] 1) Material mixing

[0081] Take 0.03 g of salicylaldehyde anilide and add it to 100 g of methyl methacrylate, and stir evenly;

[0082] Add 0.4 g of 4-vinylbenzocyclobutene and 0.12 g of (Z)-3-hexenyl-3-boronic acid catechol ester in sequence;

[0083] Add 1.2 g of cumene hydroperoxide as an initiator;

[0084] Stir for 15 minutes at a stirring speed of 300 rpm to ensure the uniformity of the solution.

[0085] 2) Thermal polymerization reaction

[0086] Gradually heat up to 60 °C and maintain for 2 hours to make the solution become viscous.

[0087] 3) Curing treatment (programmed temperature curing, water bath heating)

[0088] Primary curing: Constant temperature curing for 24 hours at 48 °C;

[0089] Secondary curing: Heat up to 65 °C and maintain for 12 hours;

[0090] Final curing: Heat up to 85 °C and maintain for 1.5 hours to complete the curing of the material.

[0091] 4) Post-treatment

[0092] Precision cutting is carried out using a CNC machine tool to produce a 4×4×0.5 cm transparent optical sheet;

[0093] Polishing is carried out using a nano-polishing solution to improve smoothness.

[0094] Comparative Example 1

[0095] The difference between this example and Example 1 is only that: 4-vinylbenzocyclobutene is not added.

[0096] Comparative Example 2

[0097] The difference between this example and Example 1 is only that: (Z)-3-hexenyl-3-boronic acid catechol ester is not added.

[0098] The test methods related to the present invention are as follows:

[0099] 1) Transmittance test

[0100] Test method: Use an ultraviolet-visible spectrophotometer (UV-Vis Spectrophotometer) to measure the transmittance of the material in the 400 - 700 nm band, and set the test light source wavelength to 550 nm (the strongest visible light transmission region).

[0101] 2) Photochromic response test

[0102] Test method: Irradiate the sample with a 365 nm ultraviolet LED light source (power 200 mW) for 10 s, and observe the color change of the material; use a 532 nm green laser (power 50 mW) to irradiate the color-changing area, and observe the formation of a three-dimensional fluorescence image; use an optical microscope (100× magnification) + high-speed camera to record the color change process. Record the time required for the material to completely change color after ultraviolet light irradiation, and the response time of green light excitation of red fluorescence.

[0103] Table 1 Test results

[0104] Light transmittance (%) Color change time (s) Fluorescent response time (s) Example 1 96.1 1.5 0.8 Example 2 95.7 1.8 1.0 Example 3 97.0 1.2 0.7 Example 4 96.5 1.4 0.9 Comparative example 1 95.0 2.1 1.3 Comparative example 2 95.3 2.0 1.1

[0105] The solid optical material of the present invention is significantly superior to the comparative examples in terms of transmittance, photochromic speed, and fluorescence excitation. This material can be widely applied to high-tech fields such as three-dimensional optical dynamic information display, anti-counterfeiting identification, and reversible optical marking.

[0106] The above is only the preferred specific implementation manner of the present invention, and the protection scope of the present invention is not limited thereto. Any simple change or equivalent replacement of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A solid optical material, characterized in that: In parts by mass, its composition includes: Salicylaldehyde aniline: 0.01-0.1 parts; Methyl methacrylate: 100 parts; 4-vinylbenzocyclobutene: 0.3-0.8 parts; (Z)-3-Hexenyl-3-boric acid catechol ester: 0.08-0.2 parts; Initiator: 0.1~3 parts.

2. A solid optical material according to claim 1, characterized in that: The initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptylnitrile, benzoyl peroxide, lauroyl peroxide, and cumene hydroperoxide.

3. A method for preparing a solid optical material, characterized in that: The steps include: 1) Material mixing: Disperse 0.01-0.1 parts of salicylaldehyde aniline uniformly in 100 parts of methyl methacrylate by mass; add 0.3-0.8 parts of 4-vinylbenzocyclobutene and 0.08-0.2 parts of (Z)-3-hexenyl-3-boric acid catechol ester in sequence; add 0.1-3 parts of initiator and stir for 10-30 minutes until completely dissolved; 2) Thermal polymerization reaction: Raise the temperature to the reaction temperature and maintain it for 0.5 to 3 hours to allow the system to undergo free radical polymerization and thicken the reaction solution; 3) Curing treatment: programmed temperature curing, water bath heating; 4) Post-processing: cutting, grinding and splicing processes are adopted.

4. The method for preparing a solid optical material according to claim 3, characterized in that: The stirring speed in the material mixing step is 300-500 rpm.

5. The method for preparing a solid optical material according to claim 3, characterized in that: The reaction temperature in the thermal polymerization step is 50-100°C.

6. The method for preparing a solid optical material according to claim 3, characterized in that: The programmed temperature curing step in the curing treatment step is: Initial curing: constant temperature curing at 45-60°C for 18-24 hours; Secondary curing: raise the temperature to 60-80°C and maintain for 6-12 hours; Final curing: Raise the temperature to 80-100°C and maintain for 1-2 hours.