An epoxy resin-based dual-curing color-changing film material and a preparation method thereof

Abstract

The application discloses an epoxy resin-based dual-curing color-changing film material and a preparation method thereof, and relates to the technical field of functional polymer materials. According to the weight parts, the film material is prepared from the following components: 35-50 parts of epoxy resin, 10-15 parts of polypropylene glycol diglycidyl ether, 3-5 parts of a cationic thermal curing agent, 3-5 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3-5 parts of 1,4-diacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 5-8 parts of modified photochromic dye, 2-4 parts of metal-organic framework nanocrystals, 30-40 parts of a solvent and 1-2 parts of an initiator. The film material has good flexibility and aging resistance, a remarkable photochromic effect and a long service life.

Description

Technical Field

[0001] This invention relates to the field of functional polymer materials technology, and in particular to an epoxy resin-based dual-curing color-changing film material and its preparation method. Background Technology

[0002] As people's demands for quality of life increase, color-changing film materials are being used more and more widely in optics, architecture, automobiles, and other fields. Currently, most common color-changing film materials on the market are based on organic small-molecule color-changing systems. While they offer some color-changing effect, they suffer from significant shortcomings in stability and durability. During long-term use, organic small molecules are prone to migration and decomposition, leading to a decline in color-changing performance and a shortened lifespan.

[0003] Some existing color-changing film materials employ a single curing method, such as photocuring or thermocuring alone. While photocuring materials offer the advantage of rapid curing, their curing depth is limited when curing complex shapes or thick coatings. Thick films are prone to the problem of "surface curing, internal uncuring," resulting in insufficient mechanical properties and chemical resistance. Thermocuring materials, on the other hand, have longer curing times, lower production efficiency, and higher energy consumption. Furthermore, the high-temperature curing process can easily cause yellowing of the material, affecting its optical properties. A single curing system cannot simultaneously meet the requirements of "rapid shaping" and "depth enhancement," resulting in an inability to achieve both optimal mechanical and color-changing properties. In addition, the cross-linked network formed by traditional curing systems (such as single thermocuring or photocuring) is not dense enough to effectively encapsulate the color-changing material, making it prone to migration or degradation during use, leading to a decrease in color reversibility.

[0004] For photochromic coating materials used in optical lenses, in addition to photochromic properties, good flexibility and optical transparency are also required. Due to the limitations of their molecular structure, traditional photochromic coating materials cannot simultaneously ensure flexibility and high visible light transmittance, thus failing to meet the requirements of high-quality optical lenses.

[0005] To address the aforementioned issues, Chinese invention patent CN112724796B discloses a photochromic composition, product, and preparation method based on epoxy modification. This composition comprises a polyol, olefinic anhydride, catalyst, alicyclic epoxy, oxetane, photochromic powder, photoinitiator, antioxidant, UV absorber, leveling agent, and defoamer. This invention introduces carbon-carbon unsaturated double bonds and flexible segments of the polyol into the epoxy system, compounded with oxetane to form a dual-curing system. The introduction of epoxy groups reduces shrinkage and improves adhesion. Then, EB radiation curing allows the photochromic composition to adhere well to the surface of a transparent substrate. This avoids damage to the photochromic powder from UV light, enabling the photochromic composition to cure into a film within seconds, improving production efficiency and product yield, and reducing energy consumption and production costs. However, its flexibility and aging resistance still need further improvement.

[0006] It is evident that developing a color-changing film material with excellent flexibility and aging resistance, significant photochromic effect, and long service life, as well as its preparation method, meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the color-changing film material field. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an epoxy resin-based dual-curing color-changing film material with excellent flexibility and aging resistance, significant photochromic effect, and long service life, as well as its preparation method.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an epoxy resin-based dual-curing color-changing film material, comprising the following components by weight: 35-50 parts epoxy resin, 10-15 parts polypropylene glycol diglycidyl ether, 3-5 parts cationic thermosetting agent, 3-5 parts 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3-5 parts 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 5-8 parts modified photochromic dye, 2-4 parts metal-organic framework nanocrystals, 30-40 parts solvent, and 1-2 parts initiator.

[0009] Preferably, the epoxy resin is hydrogenated epoxy resin EP-4080E.

[0010] Preferably, the polypropylene glycol diglycidyl ether is polypropylene glycol diglycidyl ether EPG-207.

[0011] Preferably, the cationic thermosetting agent is the cationic thermosetting agent Vicbase TC 3630.

[0012] Preferably, the solvent is at least one of xylene and n-butanol.

[0013] Preferably, the initiator is benzoin ether.

[0014] Preferably, the preparation method of the modified photochromic dye includes the following steps: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, deionized water and sodium dodecyl sulfate are added and stirred until homogeneous. Then, glycidyl methacrylate monomer is slowly added dropwise over 28-32 minutes, with continuous stirring during the addition process, maintaining the temperature at 25-30°C to obtain a pre-emulsion. Spiral pyran is added to the pre-emulsion and stirred until homogeneous. Then, azobisisobutyronitrile (AIBN) and sodium bicarbonate, purified by recrystallization, are added and stirred until homogeneous again. An emulsion polymerization reaction is carried out at 68-72°C for 3-5 hours. After the reaction, the reaction solution is cooled to room temperature. After centrifugation and washing, the solution is dried in a vacuum drying oven at 48-52°C until constant weight to obtain the modified photochromic dye.

[0015] Preferably, the ratio of deionized water, sodium dodecyl sulfate, glycidyl methacrylate monomer, spiropyran, azobisisobutyronitrile, and sodium bicarbonate is 100mL:1.5g:15g:5g:0.3g:0.5g.

[0016] Preferably, the metal-organic framework nanocrystals have an average particle size of 10-20 nm and a specific surface area greater than 500 m². 2 / g.

[0017] Preferably, the preparation method of the metal-organic framework nanocrystals includes the following steps: adding zinc nitrate, terephthalic acid and N,N-dimethylformamide into a reaction vessel, reacting at 118-122℃ for 22-25 hours, after the reaction is completed, centrifuging the product, washing it three times alternately with N,N-dimethylformamide and methanol, and finally vacuum drying at 58-62℃ for 10-14 hours to obtain the organic framework nanocrystals.

[0018] Preferably, the molar ratio of zinc nitrate, terephthalic acid, and N,N-dimethylformamide is 1:2:100.

[0019] Another objective of this invention is to provide a method for preparing the epoxy resin-based dual-curing color-changing film material, comprising the following steps: mixing each component evenly and then ultrasonically dispersing it to obtain a uniform dispersion; coating it on the surface of a substrate, and then placing it in an oven at 78-82°C for curing for 0.5-1 hour to complete the thermosetting process; simultaneously, using ultraviolet light irradiation for pre-curing during the coating process to achieve dual curing, thereby obtaining the epoxy resin-based dual-curing color-changing film material.

[0020] Preferably, the ultrasonic dispersion power is 200-300W and the dispersion time is 15-20 minutes.

[0021] Preferably, the wavelength of the ultraviolet light is 365 nm and the light intensity is 50 mW / cm². 2 The irradiation time is 3-5 minutes.

[0022] Preferably, the thickness of the epoxy resin-based dual-curing color-changing film material is 20-40 μm.

[0023] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0024] (1) The preparation method of epoxy resin-based dual-curing color-changing film material disclosed in this invention has low equipment dependence, simple process, easy control of production conditions, strong operability, low energy consumption, high preparation efficiency and high finished product qualification rate, and is suitable for continuous large-scale production. It has high promotion and application value.

[0025] (2) The epoxy resin-based dual-curing color-changing film material disclosed in this invention comprises, by weight, the following components: 35-50 parts epoxy resin, 10-15 parts polypropylene glycol diglycidyl ether, 3-5 parts cationic thermosetting agent, 3-5 parts 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3-5 parts 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 5-8 parts modified photochromic dye, 2-4 parts metal-organic framework nanocrystals, 30-40 parts solvent, and 1-2 parts initiator. Through the synergistic effect of the components, the resulting color-changing film exhibits excellent flexibility and aging resistance, significant photochromic effect, and long service life.

[0026] (3) The epoxy resin-based dual-curing color-changing film material disclosed in this invention has a cationic thermosetting agent and an initiator working together to construct a highly efficient dual-curing system. The cationic thermosetting agent initiates the ring-opening polymerization of epoxy resin under heating conditions, while the initiator generates free radicals under ultraviolet light irradiation, initiating the polymerization reaction of unsaturated double bonds (such as the double bonds in 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline). The two curing methods work synergistically, with photocuring rapidly forming a surface cross-linked layer and thermocuring penetrating deep into the interior to complete the overall cross-linking. Compared with the traditional single curing method, the cross-linking density is high, significantly improving production efficiency, while ensuring that the material can be completely cured even under complex shapes or thick coatings, thus solving the limitations of existing curing methods. The modified photochromic dye, in synergy with 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, endows the material with excellent color-changing properties. The modified photochromic dye itself possesses good photochromic characteristics, while 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline not only participates in the curing reaction, but its conjugated structure can also form an intramolecular charge-transfer complex with the photochromic dye, enhancing light absorption efficiency and achieving a rapid and significant color-changing effect. This allows for precise response to changes in light intensity, meeting the needs of intelligent dimming.

[0027] (4) The epoxy resin-based dual-curing color-changing film material disclosed in this invention comprises epoxy resin and polypropylene glycol diglycidyl ether as the basic framework, and 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6 (1H,3H,5H)-trione and metal-organic framework nanocrystals further enhance the mechanical properties. Polypropylene glycol diglycidyl ether introduces flexible segments to improve the flexibility of the material; 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6 (1H,3H,5H)-trione participates in the crosslinking reaction through its multifunctional structure, increasing the density of crosslinking points; metal-organic framework nanocrystals are uniformly dispersed in the matrix at the nanoscale, inducing the formation of a denser crosslinking network, while its high-strength inorganic-organic hybrid structure plays a role in strengthening and toughening. Metal-organic framework (MOF) nanocrystals possess high specific surface area and unique pore structures, effectively enhancing light scattering and absorption. When light shines on the material surface, more photons are captured by the MOF nanocrystals and transferred to the photochromic dye, promoting conformational changes in the dye molecules and significantly improving the material's color-changing sensitivity. The MOF nanocrystals form a stable interface with the epoxy resin matrix, restricting the migration and diffusion of small molecules (such as photochromic dyes and solvent molecules), preventing performance degradation due to small molecule loss.

[0028] (5) The epoxy resin-based dual-curing color-changing film material disclosed in this invention introduces epoxy groups into the modified photochromic dye, enabling the dye to chemically bond with the epoxy resin matrix. Compared with traditional physically doped dyes, its dispersion uniformity in the matrix is ​​higher. Chemical bonding effectively avoids dye agglomeration and migration, allowing the dye to be uniformly and stably distributed in the resin matrix, laying the foundation for the stable performance of the material. Detailed Implementation

[0029] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0030] Example 1

[0031] An epoxy resin-based dual-curing photochromic film material, by weight, comprises the following components: 35 parts epoxy resin, 10 parts polypropylene glycol diglycidyl ether, 3 parts cationic thermosetting agent, 3 parts 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3 parts 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 5 parts modified photochromic dye, 2 parts metal-organic framework nanocrystals, 30 parts solvent, and 1 part initiator.

[0032] The epoxy resin is hydrogenated epoxy resin EP-4080E; the polypropylene glycol diglycidyl ether is polypropylene glycol diglycidyl ether EPG-207; the cationic thermosetting agent is cationic thermosetting agent Vicbase TC 3630; the solvent is xylene; and the initiator is benzoin ether.

[0033] The preparation method of the modified photochromic dye includes the following steps: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, deionized water and sodium dodecyl sulfate are added and stirred until homogeneous. Then, glycidyl methacrylate monomer is slowly added dropwise over 28 minutes, with continuous stirring during the addition process. The temperature is maintained at 25°C to obtain a pre-emulsion. Spiral pyran is added to the pre-emulsion and stirred until homogeneous. Then, azobisisobutyronitrile (AIBN) purified by recrystallization and sodium bicarbonate are added, and stirring is continued until homogeneous. An emulsion polymerization reaction is carried out at 68°C for 3 hours. After the reaction, the reaction solution is cooled to room temperature. After centrifugation and washing, it is dried in a vacuum drying oven at 48°C to constant weight to obtain the modified photochromic dye. The molar ratio of deionized water, sodium dodecyl sulfate, glycidyl methacrylate monomer, spiral pyran, azobisisobutyronitrile, and sodium bicarbonate is 100 mL: 1.5 g: 15 g: 5 g: 0.3 g: 0.5 g.

[0034] The preparation method of the metal-organic framework nanocrystals includes the following steps: zinc nitrate, terephthalic acid and N,N-dimethylformamide are added to a reaction vessel and reacted at 118°C for 22 hours. After the reaction is completed, the product is centrifuged and washed three times alternately with N,N-dimethylformamide and methanol. Finally, it is vacuum dried at 58°C for 10 hours to obtain the organic framework nanocrystals. The molar ratio of zinc nitrate, terephthalic acid and N,N-dimethylformamide is 1:2:100.

[0035] A method for preparing the epoxy resin-based dual-curing color-changing film material includes the following steps: mixing the components evenly, then ultrasonically dispersing to obtain a uniform dispersion; coating the dispersion onto a substrate surface, and then curing it in an oven at 78°C for 0.5 hours to complete the thermosetting process; simultaneously, ultraviolet light irradiation is used for pre-curing during the coating process to achieve dual curing, thereby obtaining the epoxy resin-based dual-curing color-changing film material; the ultrasonic dispersion power is 200W, the dispersion time is 15 minutes; the wavelength of the ultraviolet light is 365nm, and the light intensity is 50mW / cm². 2 The irradiation time is 3 minutes; the thickness of the epoxy resin-based dual-curing color-changing film material is 30 μm.

[0036] Example 2

[0037] An epoxy resin-based dual-curing photochromic film material, by weight, comprises the following components: 40 parts epoxy resin, 12 parts polypropylene glycol diglycidyl ether, 3.5 parts cationic thermosetting agent, 3.5 parts 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3.5 parts 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 6 parts modified photochromic dye, 2.5 parts metal-organic framework nanocrystals, 33 parts solvent, and 1.2 parts initiator.

[0038] The epoxy resin is hydrogenated epoxy resin EP-4080E; the polypropylene glycol diglycidyl ether is polypropylene glycol diglycidyl ether EPG-207; the cationic thermosetting agent is cationic thermosetting agent Vicbase TC 3630; the solvent is n-butanol; and the initiator is benzoin ether.

[0039] The preparation method of the modified photochromic dye includes the following steps: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, deionized water and sodium dodecyl sulfate are added and stirred until homogeneous. Then, glycidyl methacrylate monomer is slowly added dropwise over 29 minutes, with continuous stirring during the addition process. The temperature is maintained at 26°C to obtain a pre-emulsion. Spiral pyran is added to the pre-emulsion and stirred until homogeneous. Then, azobisisobutyronitrile (AIBN) purified by recrystallization and sodium bicarbonate are added and stirred until homogeneous again. An emulsion polymerization reaction is carried out at 69°C for 3.5 hours. After the reaction, the reaction solution is cooled to room temperature. After centrifugation and washing, it is dried in a vacuum drying oven at 49°C to constant weight to obtain the modified photochromic dye. The molar ratio of deionized water, sodium dodecyl sulfate, glycidyl methacrylate monomer, spiral pyran, azobisisobutyronitrile, and sodium bicarbonate is 100mL:1.5g:15g:5g:0.3g:0.5g.

[0040] The preparation method of the metal-organic framework nanocrystals includes the following steps: zinc nitrate, terephthalic acid and N,N-dimethylformamide are added to a reaction vessel and reacted at 119°C for 23 hours. After the reaction is completed, the product is centrifuged and washed three times alternately with N,N-dimethylformamide and methanol. Finally, it is vacuum dried at 59°C for 11 hours to obtain the organic framework nanocrystals. The molar ratio of zinc nitrate, terephthalic acid and N,N-dimethylformamide is 1:2:100.

[0041] A method for preparing the epoxy resin-based dual-curing color-changing film material includes the following steps: mixing the components evenly, then ultrasonically dispersing to obtain a uniform dispersion; coating the dispersion onto a substrate surface, and then curing it in an oven at 79°C for 0.6 hours to complete the thermosetting process; simultaneously, ultraviolet light irradiation is used for pre-curing during the coating process to achieve dual curing, thereby obtaining the epoxy resin-based dual-curing color-changing film material; the ultrasonic dispersion power is 230W, the dispersion time is 16 minutes; the wavelength of the ultraviolet light is 365nm, and the light intensity is 50mW / cm². 2 The irradiation time is 3.5 minutes; the thickness of the epoxy resin-based dual-curing color-changing film material is 30 μm.

[0042] Example 3

[0043] An epoxy resin-based dual-curing photochromic film material, by weight, comprises the following components: 43 parts epoxy resin, 13 parts polypropylene glycol diglycidyl ether, 4 parts cationic thermosetting agent, 4 parts 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 4 parts 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 6.5 parts modified photochromic dye, 3 parts metal-organic framework nanocrystals, 35 parts solvent, and 1.5 parts initiator.

[0044] The epoxy resin is hydrogenated epoxy resin EP-4080E; the polypropylene glycol diglycidyl ether is polypropylene glycol diglycidyl ether EPG-207; the cationic thermosetting agent is cationic thermosetting agent Vicbase TC 3630; the solvent is xylene; and the initiator is benzoin ether.

[0045] The preparation method of the modified photochromic dye includes the following steps: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, deionized water and sodium dodecyl sulfate are added and stirred until homogeneous. Then, glycidyl methacrylate monomer is slowly added dropwise over 30 minutes, with continuous stirring during the addition process. The temperature is maintained at 28°C to obtain a pre-emulsion. Spiral pyran is added to the pre-emulsion and stirred until homogeneous. Then, azobisisobutyronitrile (AIBN) purified by recrystallization and sodium bicarbonate are added, and stirring is continued until homogeneous. An emulsion polymerization reaction is carried out at 70°C for 4 hours. After the reaction, the reaction solution is cooled to room temperature. After centrifugation and washing, it is dried in a vacuum drying oven at 50°C to constant weight to obtain the modified photochromic dye. The molar ratio of deionized water, sodium dodecyl sulfate, glycidyl methacrylate monomer, spiral pyran, azobisisobutyronitrile, and sodium bicarbonate is 100 mL: 1.5 g: 15 g: 5 g: 0.3 g: 0.5 g.

[0046] The preparation method of the metal-organic framework nanocrystals includes the following steps: zinc nitrate, terephthalic acid and N,N-dimethylformamide are added to a reaction vessel and reacted at 120°C for 23.5 hours. After the reaction is completed, the product is centrifuged and washed three times alternately with N,N-dimethylformamide and methanol. Finally, it is vacuum dried at 60°C for 12 hours to obtain the organic framework nanocrystals. The molar ratio of zinc nitrate, terephthalic acid and N,N-dimethylformamide is 1:2:100.

[0047] A method for preparing the epoxy resin-based dual-curing color-changing film material includes the following steps: mixing the components evenly, then ultrasonically dispersing to obtain a uniform dispersion; coating the dispersion onto a substrate surface, and then curing it in an oven at 80°C for 0.7 hours to complete the thermosetting process; simultaneously, ultraviolet light irradiation is used for pre-curing during the coating process to achieve dual curing, thereby obtaining the epoxy resin-based dual-curing color-changing film material; the ultrasonic dispersion power is 250W, the dispersion time is 18 minutes; the wavelength of the ultraviolet light is 365nm, and the light intensity is 50mW / cm². 2 The irradiation time is 4 minutes; the thickness of the epoxy resin-based dual-curing color-changing film material is 30 μm.

[0048] Example 4

[0049] An epoxy resin-based dual-curing photochromic film material, by weight, comprises the following components: 48 parts epoxy resin, 14 parts polypropylene glycol diglycidyl ether, 4.5 parts cationic thermosetting agent, 4.5 parts 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 4.5 parts 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 7.5 parts modified photochromic dye, 3.5 parts metal-organic framework nanocrystals, 38 parts solvent, and 1.8 parts initiator.

[0050] The epoxy resin is hydrogenated epoxy resin EP-4080E; the polypropylene glycol diglycidyl ether is polypropylene glycol diglycidyl ether EPG-207; the cationic thermosetting agent is cationic thermosetting agent Vicbase TC 3630; the solvent is n-butanol; and the initiator is benzoin ether.

[0051] The preparation method of the modified photochromic dye includes the following steps: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, deionized water and sodium dodecyl sulfate are added and stirred until homogeneous. Then, glycidyl methacrylate monomer is slowly added dropwise over 31 minutes, with continuous stirring during the addition process. The temperature is maintained at 29°C to obtain a pre-emulsion. Spiral pyran is added to the pre-emulsion and stirred until homogeneous. Then, azobisisobutyronitrile (AIBN) purified by recrystallization and sodium bicarbonate are added and stirred until homogeneous again. An emulsion polymerization reaction is carried out at 71°C for 4.5 hours. After the reaction, the reaction solution is cooled to room temperature. After centrifugation and washing, it is dried in a vacuum drying oven at 51°C to constant weight to obtain the modified photochromic dye. The molar ratio of deionized water, sodium dodecyl sulfate, glycidyl methacrylate monomer, spiral pyran, azobisisobutyronitrile, and sodium bicarbonate is 100mL:1.5g:15g:5g:0.3g:0.5g.

[0052] The preparation method of the metal-organic framework nanocrystals includes the following steps: zinc nitrate, terephthalic acid and N,N-dimethylformamide are added to a reaction vessel and reacted at 121°C for 24 hours. After the reaction is completed, the product is centrifuged and washed three times alternately with N,N-dimethylformamide and methanol. Finally, it is vacuum dried at 61°C for 13 hours to obtain the organic framework nanocrystals. The molar ratio of zinc nitrate, terephthalic acid and N,N-dimethylformamide is 1:2:100.

[0053] A method for preparing the epoxy resin-based dual-curing color-changing film material includes the following steps: mixing the components evenly, then ultrasonically dispersing to obtain a uniform dispersion; coating the dispersion onto a substrate surface, and then curing it in an oven at 81°C for 0.9 hours to complete the thermosetting process; simultaneously, ultraviolet light irradiation is used for pre-curing during the coating process to achieve dual curing, thereby obtaining the epoxy resin-based dual-curing color-changing film material; the ultrasonic dispersion power is 290W, the dispersion time is 19 minutes; the wavelength of the ultraviolet light is 365nm, and the light intensity is 50mW / cm². 2 The irradiation time is 4.5 minutes; the thickness of the epoxy resin-based dual-curing color-changing film material is 30 μm.

[0054] Example 5

[0055] An epoxy resin-based dual-curing photochromic film material, by weight, comprises the following components: 50 parts epoxy resin, 15 parts polypropylene glycol diglycidyl ether, 5 parts cationic thermosetting agent, 5 parts 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 5 parts 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 8 parts modified photochromic dye, 4 parts metal-organic framework nanocrystals, 40 parts solvent, and 2 parts initiator.

[0056] The epoxy resin is hydrogenated epoxy resin EP-4080E; the polypropylene glycol diglycidyl ether is polypropylene glycol diglycidyl ether EPG-207; the cationic thermosetting agent is cationic thermosetting agent Vicbase TC 3630; the solvent is xylene; and the initiator is benzoin ether.

[0057] The preparation method of the modified photochromic dye includes the following steps: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, deionized water and sodium dodecyl sulfate are added and stirred until homogeneous. Then, glycidyl methacrylate monomer is slowly added dropwise over 32 minutes, with continuous stirring during the addition process. The temperature is maintained at 30°C to obtain a pre-emulsion. Spiral pyran is added to the pre-emulsion and stirred until homogeneous. Then, azobisisobutyronitrile (AIBN) purified by recrystallization and sodium bicarbonate are added, and stirring is continued until homogeneous. An emulsion polymerization reaction is carried out at 72°C for 5 hours. After the reaction, the reaction solution is cooled to room temperature. After centrifugation and washing, it is dried in a vacuum drying oven at 52°C to constant weight to obtain the modified photochromic dye. The molar ratio of deionized water, sodium dodecyl sulfate, glycidyl methacrylate monomer, spiral pyran, azobisisobutyronitrile, and sodium bicarbonate is 100 mL: 1.5 g: 15 g: 5 g: 0.3 g: 0.5 g.

[0058] The preparation method of the metal-organic framework nanocrystals includes the following steps: zinc nitrate, terephthalic acid and N,N-dimethylformamide are added to a reaction vessel and reacted at 122°C for 25 hours. After the reaction is completed, the product is centrifuged and washed three times alternately with N,N-dimethylformamide and methanol. Finally, it is vacuum dried at 62°C for 14 hours to obtain the organic framework nanocrystals. The molar ratio of zinc nitrate, terephthalic acid and N,N-dimethylformamide is 1:2:100.

[0059] A method for preparing the epoxy resin-based dual-curing color-changing film material includes the following steps: mixing the components evenly, then ultrasonically dispersing to obtain a uniform dispersion; coating the dispersion onto a substrate surface, and then curing it in an oven at 82°C for 1 hour to complete the thermosetting process; simultaneously, pre-curing is performed by irradiating with ultraviolet light during the coating process to achieve dual curing, thereby obtaining the epoxy resin-based dual-curing color-changing film material; the ultrasonic dispersion power is 300W, the dispersion time is 20 minutes; the wavelength of the ultraviolet light is 365nm, and the light intensity is 50mW / cm². 2 The irradiation time is 5 minutes; the thickness of the epoxy resin-based dual-curing color-changing film material is 30 μm.

[0060] Comparative Example 1

[0061] An epoxy resin-based dual-curing color-changing film material and its preparation method are basically the same as those in Example 1, except that metal-organic framework nanocrystals and 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline are not added.

[0062] Comparative Example 2

[0063] An epoxy resin-based dual-curing color-changing film material and its preparation method are basically the same as those in Example 1, except that an equal amount of spiral pyran is used instead of the modified photochromic dye, and 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione is not added.

[0064] To further illustrate the beneficial technical effects of the epoxy resin-based dual-curing color-changing film materials involved in the various embodiments of the present invention, relevant performance tests were conducted on the epoxy resin-based dual-curing color-changing film materials involved in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1; the test methods are as follows:

[0065] (1) Visible light transmittance test: Referring to GB / T 2410-2008 "Determination of transmittance and haze of transparent plastic", a UV-Vis spectrophotometer was used to test the visible light transmittance of colorless and color-changing film materials. The test wavelength range was 380-780nm, and the average value was taken as the test result.

[0066] (2) Flexibility test: Refer to GB / T 1731-2020 "Determination of Flexibility of Paint Film and Putty Film", use a flexibility tester to make standard test pieces of film material, and conduct bending tests through shafts of different diameters to observe whether the film material cracks, peels off or other phenomena, so as to evaluate its flexibility.

[0067] (3) Yellow index test: Refer to ASTM D1925-70 "Standard test method for determining color and color difference by tristimulus values", use a colorimeter to test the yellow index of the cured film material. After aging for 1000 hours at 80℃ and 90% relative humidity, test the yellow index again and calculate the increase in yellow index.

[0068] Table 1 Performance test results of epoxy resin-based dual-curing color-changing film material

[0069] project Colorless visible light Color-changing visible light Flexibility (by shaft diameter) Yellow Index Increase Value Example 1 88.2 21.5 2mm 0.3 Example 2 88.5 20.8 1mm 0.2 Example 3 89.0 20.3 1mm 0.2 Example 4 89.2 20.0 1mm 0.1 Example 5 89.5 19.4 1mm 0.1 Comparative Example 1 86.5 24.8 3mm 0.6 Comparative Example 2 85.9 25.2 3mm 0.8

[0070] As can be seen from Table 1, the epoxy resin-based dual-curing color-changing film material disclosed in this invention has a more obvious photochromic effect, and better flexibility and aging resistance. The combination of metal-organic framework nanocrystals, 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, modified photochromic dye and 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione is beneficial to improving the above properties.

[0071] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An epoxy resin-based dual-curing color-changing film material, characterized in that, The product is made from the following components in parts by weight: 35-50 parts epoxy resin, 10-15 parts polypropylene glycol diglycidyl ether, 3-5 parts cationic thermosetting agent, 3-5 parts 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3-5 parts 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 5-8 parts modified photochromic dye, 2-4 parts metal-organic framework nanocrystals, 30-40 parts solvent, and 1-2 parts initiator. The preparation method of the modified photochromic dye includes the following steps: In a three-necked flask equipped with a stirrer, thermometer, and reflux condenser, deionized water and sodium dodecyl sulfate are added and stirred until homogeneous. Then, glycidyl methacrylate monomer is slowly added dropwise over 28-32 minutes, with continuous stirring during the addition process. The temperature is maintained at 25-30℃ to obtain a pre-emulsion. Spiral pyran is added to the pre-emulsion and stirred until homogeneous. Then, azobisisobutyronitrile (AIBN) and sodium bicarbonate, purified by recrystallization, are added and stirred until homogeneous again. An emulsion polymerization reaction is carried out at 68-72℃ for 3-5 hours. After the reaction, the reaction solution is cooled to room temperature. After centrifugation and washing, the solution is dried in a vacuum drying oven at 48-52℃ to constant weight to obtain the modified photochromic dye. The preparation method of the metal-organic framework nanocrystals includes the following steps: zinc nitrate, terephthalic acid and N,N-dimethylformamide are added to a reaction vessel and reacted at 118-122℃ for 22-25 hours. After the reaction is completed, the product is centrifuged and washed three times alternately with N,N-dimethylformamide and methanol. Finally, it is vacuum dried at 58-62℃ for 10-14 hours to obtain the organic framework nanocrystals. The molar ratio of zinc nitrate, terephthalic acid and N,N-dimethylformamide is 1:2:

100.

2. The epoxy resin-based dual-curing color-changing film material according to claim 1, characterized in that, The epoxy resin is hydrogenated epoxy resin EP-4080E; the polypropylene glycol diglycidyl ether is polypropylene glycol diglycidyl ether EPG-207.

3. The epoxy resin-based dual-curing color-changing film material according to claim 1, characterized in that, The cationic thermosetting agent is Vicbase TC 3630; the solvent is at least one of xylene and n-butanol; and the initiator is benzoin ether.

4. The epoxy resin-based dual-curing color-changing film material according to claim 1, characterized in that, The ratio of deionized water, sodium dodecyl sulfate, glycidyl methacrylate monomer, spiropyran, azobisisobutyronitrile, and sodium bicarbonate is 100mL:1.5g:15g:5g:0.3g:0.5g.

5. The epoxy resin-based dual-curing color-changing film material according to claim 1, characterized in that, The metal-organic framework nanocrystals have an average particle size of 10-20 nm and a specific surface area greater than 500 m². 2 / g.

6. A method for preparing an epoxy resin-based dual-curing color-changing film material according to any one of claims 1-5, characterized in that, The process includes the following steps: after mixing the components evenly, ultrasonically disperse them to obtain a uniform dispersion; coat the substrate surface, and then place it in an oven at 78-82℃ for 0.5-1 hour to complete the thermal curing process. At the same time, ultraviolet light is used for pre-curing during the coating process to achieve double curing and obtain an epoxy resin-based double-cured color-changing film material.

7. The method for preparing the epoxy resin-based dual-curing color-changing film material according to claim 6, characterized in that, The ultrasonic dispersion power is 200-300W, and the dispersion time is 15-20 minutes; the ultraviolet light wavelength is 365nm, and the light intensity is 50mW / cm². 2 The irradiation time is 3-5 minutes.

8. The method for preparing the epoxy resin-based dual-curing color-changing film material according to claim 6, characterized in that, The thickness of the epoxy resin-based dual-curing color-changing film material is 20-40 μm.