Photochromic ink and preparation method thereof

Abstract

The invention relates to photochromic ink and a preparation method thereof, and relates to the field of photochromic ink, the photochromic ink comprises the following raw materials by weight: 10-15 parts of photochromic microcapsules, 15-60 parts of an organic solvent, 25-35 parts of resin, 0.5-1 part of an antifoaming agent, 0.5-1 part of a leveling agent, 0.5-1 part of wax powder, 4-8 parts of an auxiliary agent, and 5-20 parts of a filler; a core material of the photochromic microcapsule comprises 2-10 parts of a photochromic material, 0.5-2 parts of a light stabilizer and 63-100 parts of a diluent, and a wall material of the photochromic microcapsule comprises polymethyl methacrylate and silicon dioxide. According to the photochromic ink, the light stabilizer and the photochromic material are wrapped in the double-layer wall material together, so that the weather resistance of the photochromic ink is improved.

Description

Technical Field

[0001] The present application relates to the field of photochromic ink, and in particular to a photochromic ink and a preparation method thereof. Background Art

[0002] UV photochromic ink is a special coating that can change color under ultraviolet light, and is widely used in anti-counterfeiting labels, smart windows, sunglasses, and building exterior wall decoration. Most of the UV photochromic inks in the prior art are based on organic photochromic materials, such as spiropyrans, spiropyrans, and dioxane compounds, which can change from colorless to colored or from one color to another under ultraviolet light; Although existing UV photochromic inks show good color change effects in initial application, their durability and color stability show obvious deficiencies as the use time increases: When the existing photochromic ink is exposed to ultraviolet rays and the natural environment for a long time, its photochromic performance will gradually decay. Specifically, the photochromic material in the ink will change its chemical structure under the continuous irradiation of ultraviolet rays, resulting in a decrease in color change efficiency and a decrease in the visibility of color change, which will weaken the anti-counterfeiting effect. Based on this, a photochromic ink with high weather resistance is needed. Summary of the invention

[0003] In order to solve the above technical problems, the present application provides a photochromic ink and a preparation method thereof.

[0004] The present application provides a photochromic ink and a preparation method thereof, which adopts the following technical scheme: In a first aspect, the present application provides a photochromic ink, the raw materials of which are calculated by weight and comprise 10-15 parts of photochromic microcapsules, 40-60 parts of organic solvents, 25-35 parts of resins, 0.5-1 parts of defoaming agents, 0.5-1 parts of leveling agents, 0.5-1 parts of wax powders, and 5-20 parts of fillers; the core material of the photochromic microcapsules comprises 2-10 parts of photochromic materials, 0.5-2 parts of light stabilizers, and 63-100 parts of diluents, and the wall material of the photochromic microcapsules comprises polymethyl methacrylate and silica.

[0005] By adopting the above technical solution, the present application adopts photochromic microcapsules to effectively protect the photochromic material. Polymethyl methacrylate has good film-forming properties and has a good coating effect on the core material. Silicon dioxide has good mechanical properties. By combining inorganic wall materials with organic wall materials, the wall materials of the photochromic microcapsules have higher density and higher structural strength, and at the same time have good light transmittance, so that the core material is fully isolated from the outside world and the penetration of light is guaranteed, which effectively reduces the phenomenon of oxidation of the photochromic material exposed to the external environment, thereby effectively improving the weather resistance of the photochromic microcapsules. At the same time, by coating the light stabilizer and the photochromic material together inside the photochromic microcapsules, the light fastness of the photochromic material is effectively extended, the weather resistance of the photochromic material is improved, and the weather resistance of the photochromic ink is thereby improved.

[0006] In summary, the various substances cooperate with each other to give full play to the synergistic effect, thereby effectively improving the weather resistance of photochromic ink.

[0007] Preferably, the method for preparing the photochromic microcapsules comprises the following steps: S1, adding a photochromic material and a light stabilizer to a diluent, stirring and mixing to obtain a core material, and uniformly mixing the core material with methyl methacrylate, ethyl orthosilicate and an initiator to prepare an oil phase; S2, mixing the emulsifier and water evenly to obtain an aqueous phase, mixing the oil phase in step S1 with the aqueous phase, and homogenizing for 10-15 minutes to obtain a mixed solution; S3. Adjust the pH value of the mixed solution to 10-11 with ammonia water, heat the mixed solution to 53-57°C at 500-550rpm and condense reflux to react for 2-4h, then adjust the temperature of the mixed solution to 75-78°C, react for 3.5-4.5h, then adjust the temperature of the mixed solution to 80-82°C, react for 2-2.5h, centrifuge the reaction product, wash with water and dry to obtain photochromic microcapsules.

[0008] By adopting the above technical scheme, the present application forms polymethyl methacrylate through free radical polymerization of methyl methacrylate, forms silicon dioxide through hydrolysis and condensation of tetraethyl orthosilicate, and polymethyl methacrylate and silicon dioxide are combined to form a wall material coated on the outer surface of the core material, so that the wall material has good coating properties and good structural strength, thereby forming an effective protection for the photochromic material.

[0009] Preferably, in step S1, the mass ratio of the core material, methyl methacrylate, tetraethyl orthosilicate and the initiator is (4-6):(4-6):(2-4):(0.04-0.06).

[0010] By adopting the above technical scheme, the present application improves the structural integrity and coating uniformity of the wall material of the photochromic microcapsule by optimizing the mass ratio between the core material, methyl methacrylate, ethyl orthosilicate and the initiator, thereby further improving the protective effect on the photochromic material and further improving the weather resistance of the photochromic ink.

[0011] Preferably, the mass concentration of the emulsifier in the aqueous phase in step S2 is 25-35 g / L.

[0012] By adopting the above technical scheme, the present application controls the mass concentration of the emulsifier in the aqueous phase so that the particle size distribution of the photochromic microcapsules is uniform and the coating integrity of the wall material on the core material is good, thereby further improving the protective effect of the photochromic microcapsules on the photochromic material and further improving the weather resistance of the photochromic ink.

[0013] Preferably, the photochromic material in step S1 is selected from one or more of spiropyran, diarylethene and naphthopyran, and the light stabilizer in step S1 is a hindered amine light stabilizer.

[0014] By adopting the above technical scheme, the energy barrier for the excitation of the structure of photochromic materials such as spiropyran, diarylethene and naphthopyran is higher, so that it is more resistant to aging, thereby improving the weather resistance of photochromic ink.

[0015] In a specific embodiment, spiropyran is used as the photochromic material to prepare the photochromic ink.

[0016] In a specific embodiment, naphthopyran is used as the photochromic material to prepare the photochromic ink.

[0017] In a specific embodiment, cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethylene in diarylethene compounds is used as the photochromic material to prepare the photochromic ink.

[0018] Among them, the service life of the photochromic ink prepared with spiropyran as the photochromic material was increased by 50 cycles compared with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethylene, and the service life of the photochromic ink prepared with naphthopyran as the photochromic material was increased by 60 cycles compared with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethylene. It may be that the wall material prepared by spiropyran and naphthopyran in combination with polymethyl methacrylate and silica has a stronger linking effect, thereby improving the structural stability of the photochromic microcapsules and further improving the weather resistance of the photochromic ink.

[0019] Hindered amine light stabilizer is a kind of highly efficient light stabilizer, which can effectively capture free radicals in the degradation chain reaction of photochromic materials and inhibit the chain reaction of degradation and aging of photochromic materials by removing and inactivating peroxide free radicals, thereby improving the weather resistance of photochromic microcapsules and further improving the weather resistance of photochromic inks.

[0020] Preferably, the resin is a polyether-modified epoxy resin.

[0021] By adopting the above technical solution, the polyether-modified epoxy resin has more flexible chains, soft structure and high toughness, which is conducive to maintaining the integrity of the wall material structure of the photochromic microcapsules in the polyether-modified epoxy resin, reducing the phenomenon of wall material damage in the photochromic microcapsules, and thus improving the weather resistance of the photochromic microcapsules. In addition, after the introduction of the flexible chain segment, the glass transition temperature of the polyether-modified epoxy resin is reduced, which is conducive to improving the weather resistance of the photochromic ink.

[0022] Preferably, the preparation method of the polyether-modified epoxy resin comprises the following steps: a1. Dehydrate polyethylene glycol monomethyl ether in vacuum at 110-120°C, then cool to 40-50°C, add toluene diisocyanate and stir to mix, react for 2-2.5h, then heat to 70-75°C, react for 1-1.5h to obtain a prepolymer; a2. Dehydrate the epoxy resin under vacuum at 100-110°C, then cool to 40-50°C, add the prepolymer in step a1, disperse and stir evenly, then heat to 75-80°C, react for 3-3.5h, and obtain a polyether-modified epoxy resin; The molar ratio of the polyethylene glycol monomethyl ether to the toluene diisocyanate in the step a1 is (1-1.2):(0.9-1.1).

[0023] By adopting the above technical scheme, the flexible polyether chain segment is effectively grafted into the epoxy resin, thereby increasing the content of the flexible chain segment in the epoxy resin, effectively improving the toughness of the epoxy resin, which is beneficial to the photochromic microcapsule to maintain structural integrity and further improving the weather resistance of the photochromic ink.

[0024] Preferably, the mass ratio of the prepolymer to the epoxy resin in step a2 is (0.5-1):(9-9.5).

[0025] By adopting the above technical solution, the present application controls the mass ratio of prepolymer to epoxy resin so that the polyether-modified epoxy resin has a higher grafting rate, thereby increasing the content of the flexible segment, which is beneficial to improving the weather resistance of the photochromic ink.

[0026] On the other hand, the present application provides a method for preparing photochromic ink, which comprises the following steps: weighing photochromic microcapsules, organic solvents, resins, defoamers, leveling agents, wax powders and fillers by weight, and mixing and stirring the above components to obtain photochromic ink.

[0027] In summary, this application has the following beneficial technical effects: 1. The present application improves the protective effect of photochromic materials by combining polymethyl methacrylate and silicon dioxide as the wall material of photochromic microcapsules, and further improves the weather resistance of photochromic ink by encapsulating the light stabilizer and the photochromic material as the core material inside the photochromic microcapsules; 2. The present application improves the structural stability of the photochromic microcapsules by preparing a polyether-modified epoxy resin with a high flexible segment content, thereby further improving the weather resistance of the photochromic ink. DETAILED DESCRIPTION

[0028] The specific embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

[0029] Material Source Spiropyran, purity 98%, purchased from Guangzhou Chongyu Industrial Materials Technology Co., Ltd.; Naphthopyran, purity 98%, purchased from Wuhan Shuer Biotechnology Co., Ltd.; cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethylene, purity 98%, product number 32238004, purchased from Shanghai Zhenzhun Biotechnology Co., Ltd.; The polymer hindered amine light stabilizer Chimassorrb 944 was purchased from Ciba Specialty Chemicals (China) Co., Ltd. n-Octane was purchased from Shanghai Bailingwei Chemical Technology Co., Ltd.; Methyl methacrylate was purchased from Sinopharm Chemical Reagent Co., Ltd.; Tetraethyl orthosilicate was purchased from Sinopharm Chemical Reagent Co., Ltd.; Azobisisobutyronitrile was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Hexadecyltrimethylbromide was purchased from Sinopharm Chemical Reagent Co., Ltd.; Polyvinyl pyrrolidone was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Ammonia was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Polyethylene glycol monomethyl ether (MPEG-650) industrial grade was purchased from Jiangsu Subote New Materials Co., Ltd.; Toluene diisocyanate was purchased from Sinopharm Chemical Reagent Co., Ltd.; Epoxy resin E51: epoxy value 0.51 mol / 100 g, industrial grade, purchased from Kunshan Nanya Resin Factory; Polysiloxane was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Xylene was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Acrylate-modified polydimethylsiloxane was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Polyethylene wax Sinopharm Chemical Reagent Co., Ltd.; Titanium dioxide was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Rosin-modified phenolic resin, with an active ingredient content of 90%, CAS No. 68186-14-1, was purchased from Dongguang County Jinda Chemical Co., Ltd.

[0030] Preparation Example 1-1 The preparation method of photochromic microcapsules comprises the following steps: S1. Add 2 g of spiropyran and 2 g of polymer hindered amine light stabilizer 944 to 63 g of diluent, stir and mix to obtain core material, and evenly mix 4 g of core material with 6 g of methyl methacrylate, 2 g of ethyl orthosilicate and 0.06 g of initiator to prepare an oil phase; S2, the emulsifier and water are mixed uniformly to obtain an aqueous phase, the concentration of the emulsifier in the aqueous phase is 25g / L, the oil phase in step S1 is mixed with the aqueous phase (the volume ratio of the oil phase to the aqueous phase is 1:7) and homogenized for 10-15min to obtain a mixed solution; S3. The pH value of the mixed solution was adjusted to 10 with ammonia water, the mixed solution was heated to 53° C. at 550 rpm and condensed under reflux for 4 hours, then the temperature of the mixed solution was adjusted to 75° C. and reacted for 4.5 hours, then the temperature of the mixed solution was adjusted to 80° C. and reacted for 2.5 hours, the reaction product was centrifuged, washed with water and dried to obtain photochromic microcapsules.

[0031] The diluent in step S1 is n-octane, the initiator is azobisisobutyronitrile, and the emulsifier in step S2 is composed of hexadecyltrimethylbromide and polyvinylpyrrolidone in a mass ratio of 1:1.

[0032] Preparation Example 1-2 The preparation method of photochromic microcapsules comprises the following steps: S1. Add 10 g of spiropyran and 0.5 g of polymer hindered amine light stabilizer 944 to 100 g of diluent, stir and mix to obtain core material, and evenly mix 6 g of core material with 4 g of methyl methacrylate, 4 g of ethyl orthosilicate and 0.04 g of initiator to prepare an oil phase; S2, the emulsifier and water are mixed uniformly to obtain an aqueous phase, the concentration of the emulsifier in the aqueous phase is 35g / L, the oil phase in step S1 is mixed with the aqueous phase (the volume ratio of the oil phase to the aqueous phase is 1:7) and homogenized for 10-15min to obtain a mixed solution; S3. The pH value of the mixed solution was adjusted to 11 with ammonia water, the mixed solution was heated to 57° C. at 500 rpm and condensed under reflux for 2 h, then the temperature of the mixed solution was adjusted to 78° C. and reacted for 3.5 h, then the temperature of the mixed solution was adjusted to 82° C. and reacted for 2 h, the reaction product was centrifuged, washed with water and dried to obtain photochromic microcapsules.

[0033] The diluent in step S1 is n-octane, the initiator is azobisisobutyronitrile, and the emulsifier in step S2 is composed of hexadecyltrimethylbromide and polyvinylpyrrolidone in a mass ratio of 1:1.

[0034] Preparation Example 1-3 The difference from Preparation Example 1-1 is that the spiropyran in step S1 is replaced by cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethylene.

[0035] Preparation Example 1-4 The difference from Preparation Example 1-1 is that the spiropyran in step S1 is replaced by naphthopyran.

[0036] Preparation Example 2-1 The difference from Preparation Example 1-1 is that in step S1, the core material is 2 g, methyl methacrylate is 8 g, tetraethyl orthosilicate is 1 g, and the initiator is 0.1 g.

[0037] Preparation Example 2-2 The difference from Preparation Example 1-1 is that in step S1, the core material is 8 g, methyl methacrylate is 2 g, tetraethyl orthosilicate is 6 g, and the initiator is 0.02 g.

[0038] Preparation Example 3-1 The difference from Preparation Example 1-1 is that in step S2, the concentration of the emulsifier in the aqueous phase is 15 g / L.

[0039] Preparation Example 3-2 The difference from Preparation Example 1-1 is that in step S2, the concentration of the emulsifier in the aqueous phase is 45 g / L.

[0040] Preparation Example 4-1 The preparation method of polyether modified epoxy resin comprises the following steps: a1. Vacuum dehydrate 40 g of polyethylene glycol monomethyl ether at 110° C., then cool to 50° C., add 12 g of toluene diisocyanate and stir to mix, react for 2 h, then heat to 75° C. and react for 1 h to obtain a prepolymer.

[0041] a2. Dehydrate 90g of epoxy resin under vacuum at 110°C, then cool to 40°C, add 10g of prepolymer in step a1, disperse and stir evenly, then heat to 90°C and react for 3h to obtain polyether-modified epoxy resin.

[0042] Preparation Example 4-2 The preparation method of polyether modified epoxy resin comprises the following steps: a1. Vacuum dehydrate 50 g of polyethylene glycol monomethyl ether at 120° C., then cool to 40° C., add 10 g of toluene diisocyanate and stir to mix, react for 2.5 h, then heat to 70° C. and react for 1 h to obtain a prepolymer.

[0043] a2. Dehydrate 95g of epoxy resin under vacuum at 100°C, then cool to 50°C, add 5g of prepolymer in step a1, disperse and stir evenly, then heat to 80°C, react for 3.5h, and obtain polyether-modified epoxy resin.

[0044] Preparation Example 4-3 The difference from Preparation Example 4-1 is that in step a2, the epoxy resin is 100 g and the prepolymer is 3 g.

[0045] Preparation Example 4-4 The difference from Preparation Example 4-1 is that in step a2, the epoxy resin is 85 g and the prepolymer is 12 g.

[0046] Comparative Preparation Example 1 The difference from Preparation Example 1-1 is that no ethyl orthosilicate is added in step S1.

[0047] Example 1 The preparation method of the photochromic ink comprises the following steps: 10g of photochromic microcapsules, 60g of organic solvent (xylene), 25g of resin, 1g of defoaming agent (polysiloxane), 0.5g of leveling agent (acrylate-modified polydimethylsiloxane), 1g of wax powder (polyethylene wax) and 5g of filler (titanium dioxide) are mixed and stirred evenly to obtain a photochromic ink.

[0048] The photochromic microcapsules are selected from the photochromic microcapsules prepared in Preparation Example 1-1, and the resin is selected from the polyether-modified epoxy resin prepared in Preparation Example 4-1.

[0049] Example 2 The preparation method of the photochromic ink comprises the following steps: 15 g of photochromic microcapsules, 40 g of organic solvent (xylene), 35 g of resin, 0.5 g of defoaming agent (polysiloxane), 1 g of leveling agent (acrylate-modified polydimethylsiloxane), 0.5 g of wax powder (polyethylene wax) and 20 g of filler (titanium dioxide) are mixed and stirred evenly to obtain a photochromic ink.

[0050] The photochromic microcapsules are selected from the photochromic microcapsules prepared in Preparation Example 1-2, and the resin is selected from the polyether-modified epoxy resin prepared in Preparation Example 4-2.

[0051] Embodiment 3-4 The difference from Example 1 is that the photochromic microcapsules are the photochromic microcapsules prepared in Preparation Examples 1-3 and 1-4 respectively.

[0052] Embodiment 5-6 The difference from Example 1 is that the photochromic microcapsules are the photochromic microcapsules prepared in Preparation Example 2-1 and Preparation Example 2-2 respectively.

[0053] Embodiment 7-8 The difference from Example 1 is that the photochromic microcapsules are the photochromic microcapsules prepared in Preparation Example 3-1 and Preparation Example 3-2 respectively.

[0054] Examples 9-10 The difference from Example 1 is that the resins used are the polyether-modified epoxy resins prepared in Preparation Example 4-3 and Preparation Example 4-4 respectively.

[0055] Comparative Example 1 The difference from Example 1 is that the photochromic microcapsules are the photochromic microcapsules prepared in Comparative Preparation Example 1.

[0056] Comparative Example 2 The difference from Example 1 is that the resin is a commercially available rosin-modified phenolic resin.

[0057] Performance Testing The photochromic ink prepared in Examples 1-10 and Comparative Examples 1-2 was made into a sample card, and the sample card was placed in a dark box, with a long arc xenon lamp inside, the cycle on and off period was 60 seconds, the xenon lamp was on and off for 30 seconds, and an ultraviolet spectrometer was used to detect the absorption at a fixed wavelength, and the number of cycles used for the cyclic absorption peak to drop by more than 10% was recorded as the service life. The specific results are shown in Table 1: Table 1 Weathering resistance test data Detection object Service life (cycles) Example 1 1520 Example 2 1550 Example 3 1470 Example 4 1530 Example 5 1260 Example 6 1290 Example 7 1180 Example 8 1210 Example 9 1320 Example 10 1300 Comparative Example 1 910 Comparative Example 2 970 It can be seen from Table 1 that the service life of the photochromic inks prepared in Examples 1 and 2 of the present application is 1520 cycles and 1550 cycles, indicating that the photochromic inks prepared in Examples 1 and 2 of the present application have good weather resistance.

[0058] The service life of the photochromic ink prepared in Example 1 of the present application is increased by 50 cycles compared with that prepared in Example 3 of the present application, and the service life of the photochromic ink prepared in Example 4 of the present application is increased by 60 cycles compared with that prepared in Example 3 of the present application, indicating that the spiropyran and naphthopyran in the photochromic material provided by the present application have a tighter and stronger linking effect than the wall material prepared by the composite of diarylethene compounds, polymethyl methacrylate and silica, thereby making the photochromic ink using spiropyran and naphthopyran as the photochromic material have higher weather resistance.

[0059] The service life of the photochromic ink prepared in Example 1 of the present application is increased by 260 cycles and 230 cycles respectively compared with those prepared in Examples 5 and 6 of the present application. The service life of the photochromic ink prepared in Example 2 of the present application is increased by 290 cycles and 260 cycles respectively compared with those prepared in Examples 5 and 6 of the present application. This indicates that when the mass ratio of the core material, methyl methacrylate, tetraethyl orthosilicate and initiator in the preparation process of the photochromic microcapsules is (4-6):(4-6):(2-4):(0.04-0.06), the prepared photochromic microcapsules have higher coating uniformity and structural integrity, thereby improving the weather resistance of the photochromic ink.

[0060] The service life of the photochromic ink prepared in Example 1 of the present application is increased by 340 cycles and 310 cycles respectively compared with those prepared in Example 7 and Example 8 of the present application. The service life of the photochromic ink prepared in Example 2 of the present application is increased by 360 cycles and 330 cycles respectively compared with those prepared in Example 7 and Example 8 of the present application. This indicates that when the mass ratio of the core material, methyl methacrylate, ethyl orthosilicate and initiator in the preparation process of the photochromic microcapsules is (4-6):(4-6):(2-4):(0.04-0.06) and the mass concentration of the emulsifier in the aqueous phase is 25-35 g / L, the particle size distribution of the prepared photochromic microcapsules is uniform, and the outer surface of the core material can form a complete wall material, which further improves the protective effect on the photochromic material and further improves the weather resistance of the photochromic ink.

[0061] The service life of the photochromic ink prepared in Example 1 of the present application is increased by 200 cycles and 220 cycles respectively compared with that prepared in Example 9 and Example 10 of the present application, and the service life of the photochromic ink prepared in Example 2 of the present application is increased by 220 cycles and 240 cycles respectively compared with that prepared in Example 9 and Example 10 of the present application, indicating that when the mass ratio of the prepolymer to the epoxy resin in step a2 in the preparation process of the polyether-modified epoxy resin is (0.5-1):(9-9.5), the prepared polyether-modified epoxy resin has a higher grafting rate, so that the polyether-modified epoxy resin has a higher flexible segment content, thereby improving the structural stability of the photochromic microcapsules in the photochromic ink, and further improving the weather resistance of the photochromic ink.

[0062] The service life of the photochromic ink prepared in Example 1 of the present application is increased by 610 cycles compared with that in Comparative Example 1 of the present application, indicating that the photochromic microcapsule wall material combining polymethyl methacrylate and silica prepared in the present application has a good effect on improving the weather resistance of the photochromic microcapsules, thereby effectively improving the weather resistance of the photochromic ink.

[0063] The service life of the photochromic ink prepared in Example 1 of the present application is increased by 550 cycles compared with that in Comparative Example 2 of the present application, indicating that the polyether-modified epoxy resin provided in the present application has a better effect on the weather resistance of the photochromic ink than the commercially available rosin-modified phenolic resin.

Claims

1. A photochromic ink, characterized in that: The raw materials thereof are calculated by weight and comprise 10-15 parts of photochromic microcapsules, 40-60 parts of organic solvents, 25-35 parts of resins, 0.5-1 parts of defoaming agents, 0.5-1 parts of leveling agents, 0.5-1 parts of wax powders, and 5-20 parts of fillers; the core material of the photochromic microcapsules comprises 2-10 parts of photochromic materials, 0.5-2 parts of light stabilizers, and 63-100 parts of diluents; and the wall material of the photochromic microcapsules comprises polymethyl methacrylate and silicon dioxide.

2. The photochromic ink according to claim 1, characterized in that: The preparation method of the photochromic microcapsule comprises the following steps: S1, adding a photochromic material and a light stabilizer to a diluent, stirring and mixing to obtain a core material, and uniformly mixing the core material with methyl methacrylate, ethyl orthosilicate and an initiator to prepare an oil phase; S2, mixing the emulsifier and water evenly to obtain an aqueous phase, mixing the oil phase in step S1 with the aqueous phase, and homogenizing for 10-15 minutes to obtain a mixed solution; S3. The pH value of the mixed solution is adjusted to 10-11 with ammonia water, the mixed solution is heated to 53-57°C at 500-550 rpm and condensed and refluxed for reaction for 2-4 h, then the temperature of the mixed solution is adjusted to 75-78°C, the reaction is carried out for 3.5-4.5 h, then the temperature of the mixed solution is adjusted to 80-82°C, the reaction is carried out for 2-2.5 h, the reaction product is centrifuged, washed with water and dried to obtain photochromic microcapsules.

3. A photochromic ink according to claim 2, characterized in that: In the step S1, the mass ratio of the core material, methyl methacrylate, tetraethyl orthosilicate and the initiator is (4-6):(4-6):(2-4):(0.04-0.06).

4. The photochromic ink according to claim 2, characterized in that: The mass concentration of the emulsifier in the water phase in step S2 is 25-35 g / L.

5. The photochromic ink according to claim 2, characterized in that: The photochromic material in step S1 is selected from one or more of spiropyran, diarylethene and naphthopyran, and the light stabilizer in step S1 is a hindered amine light stabilizer.

6. The photochromic ink according to claim 1, characterized in that: The resin is a polyether modified epoxy resin.

7. The photochromic ink according to claim 6, characterized in that: The preparation method of the polyether-modified epoxy resin comprises the following steps: a1. Dehydrate polyethylene glycol monomethyl ether in vacuum at 110-120°C, then cool to 40-50°C, add toluene diisocyanate and stir to mix, react for 2-2.5h, then heat to 70-75°C, react for 1-1.5h to obtain a prepolymer; a2. Dehydrate the epoxy resin under vacuum at 100-110°C, then cool to 40-50°C, add the prepolymer in step a1, disperse and stir evenly, then heat to 80-90°C, react for 3-3.5h, and obtain a polyether-modified epoxy resin; The mass ratio of the polyethylene glycol monomethyl ether to the toluene diisocyanate in the step a1 is (4-5):(1-1.2).

8. The photochromic ink according to claim 7, characterized in that: The mass ratio of the prepolymer to the epoxy resin in the step a2 is (0.5-1):(9-9.5).

9. The method for preparing the photochromic ink according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: weighing photochromic microcapsules, organic solvents, resins, defoamers, leveling agents, wax powders and fillers by weight, and mixing and stirring the above components evenly to prepare the photochromic ink.