A photochromic printing dye and its preparation method and application

Abstract

The present application relates to the field of printing dye technology, and more particularly to a photochromic printing dye, its preparation method, and its application. The photochromic printing dye provided herein is obtained by dispersing a disperse dye and microcapsules in an organic continuous phase. The disperse dye is selected from indigo dye, anthraquinone dye, or triarylmethane dye. The core material of the microcapsules is an oxidant, and the shell material of the microcapsules is a SiO2 complex. The printing dye provided herein contains microcapsules with an oxidant as the core material. During the washing process, the oxidant is slowly released from the shell material and has strong oxidizing properties. On the one hand, it can have a bactericidal effect. On the other hand, during the drying process, it can react with the disperse dye that is prone to photooxidation, causing the disperse dye to slowly decompose and fade.

Description

Technical Field

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

[0002] Textiles such as towels, underwear, and bed sheets absorb skin oils, sweat, cell debris, and other organic matter during daily use. Long-term use can easily breed bacteria and fungi, potentially affecting health. Therefore, these products require regular replacement during use. However, users often cannot visually assess the performance and duration of textile products, making it difficult to replace them within a reasonable timeframe.

[0003] A color-changing label is pasted on the inside of the towel, ensuring that the label is in contact with the skin. After the towel has been used for a period of time, the label will change color due to the absorption of moisture and sweat. When the label changes from its original color to another color, it means that the towel has been used for a long time and needs to be replaced. For example, patent JP7130292B1 discloses a towel that uses a marked cloth on the towel. After repeated washing, the mark disappears or appears, thereby judging the service life. However, the color-changing label may fall off due to friction, washing, etc., thus affecting its reminder function. In addition, long-term use of the color-changing label may cause damage to the towel fibers, affecting the service life of the towel. Summary of the Invention

[0004] An embodiment of the present application provides a photochromic printing dye that can be printed on textiles to form a printed icon. After a certain number of washing and sun exposure cycles, the printed icon fades, reminding the user to replace it in time, thereby solving the problem of color-changing labels being easily detached when pasted on textiles in related technologies.

[0005] In the first aspect, the present application provides a photochromic printing dye, which is obtained by dispersing a disperse dye and a microcapsule in an organic continuous phase, wherein the disperse dye is selected from indigo dye, anthraquinone dye or triarylmethane dye, the core material of the microcapsule is an oxidant, and the shell material of the microcapsule is a SiO2 complex.

[0006] In some embodiments, the oxidant is selected from any one of sodium ferrate, ferrous sulfate, polyferric sulfate, sodium hypochlorite, aluminum trifluoride or periodic acid.

[0007] In some embodiments, the organic continuous phase is selected from any one of ethylene glycol, 1,2-propylene glycol, and glycerol.

[0008] In a second aspect, the present application also provides a method for preparing the above-mentioned photochromic printing dye, comprising the following steps:

[0009] S101, using a high-speed shearing dispersing disk to fully disperse the disperse dye in the organic continuous phase at room temperature to obtain a disperse dye solution;

[0010] S102, adding an anti-settling agent to the disperse dye solution at room temperature and fully dissolving it, then adding microcapsules and uniformly dispersing them to obtain a photochromic printing dye.

[0011] In some embodiments, the microcapsules are prepared by the following process:

[0012] Add hydrophilic mesoporous nano-SiO2 into the oxidant solution, and evacuate the solution to completely adsorb the oxidant solution onto the nano-SiO2 particles;

[0013] Adding an organic solvent to the emulsifier and fully dissolving it to obtain an oil phase solution;

[0014] Add the nano-SiO2 particles adsorbing the oxidant solution into the oil phase solution and stir at a speed of 500 to 2000 rpm to obtain an emulsion with uniform particle size;

[0015] The shell material solution is added to the emulsion, and an alkaline solution is added to adjust the pH value to 7-10. The reaction is carried out at 30-60° C. for 5-12 hours. After the reaction is completed, the microcapsules are obtained by filtering, washing, and drying.

[0016] In some embodiments, the organic solvent is a mixture of one or more of n-hexane, cyclohexane, toluene, xylene, and diethyl ether.

[0017] In some embodiments, the emulsifier is a mixture of one or more of Tween-80, polyvinyl alcohol, OP-10, styrene-maleic anhydride copolymer, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate.

[0018] In some embodiments, the shell material is a mixture of one or more of ethyl orthosilicate, tetrabutyl titanate, KH550, KH560, and KH570.

[0019] In some embodiments, the alkaline solution is selected from any one of sodium hydroxide, potassium hydroxide, calcium hydroxide, and triethanolamine.

[0020] In some embodiments, in the oxidant solution, the mass ratio of the oxidant to deionized water is 0.5-3.

[0021] In some embodiments, the amount of the emulsifier added is 1% to 5% of the mass of the oxidant solution.

[0022] In some embodiments, the added amount of the shell material is 0.5 to 2 times the mass of the oxidant solution.

[0023] In some embodiments, the weight ratio of the disperse dye to the organic continuous phase is 1:5 to 1:15.

[0024] In some embodiments, the anti-settling agent is a mixture of one or more of organic montmorillonite, polyethylene wax, and non-ionic surfactant.

[0025] In some embodiments, the mass concentration of the anti-settling agent in the photochromic printing dye is 1‰ to 1%.

[0026] In some embodiments, the mass concentration of the microcapsules in the photochromic printing dye is 2‰ to 2%.

[0027] In a third aspect, the present application also provides the above-mentioned photochromic printing dye added to screen printing paste, screen thermal transfer paste or inkjet thermal transfer paste for printing textiles.

[0028] The beneficial effects of the technical solution provided by this application include:

[0029] 1. The printing dye provided in this application contains microcapsules with an oxidant as the core material. The shell material of the microcapsule is a double-layer composite structure with an inner layer of SiO2 and an outer layer of SiO2 or TiO2. The oxidant is slowly released from the shell material during the washing process and has strong oxidizing properties. On the one hand, it can have a bactericidal effect. On the other hand, during the drying process, it can react with disperse dyes that are prone to photooxidation reactions, causing the disperse dyes to slowly decompose and fade;

[0030] 2. The printing dye provided in this application is printed on a textile as a printed icon. After a certain number of washing and sun exposure cycles, the printed icon slowly fades from the original color A to colorless or the target color B. When the printed icon has completely faded or reaches the target color, it indicates that the textile has reached the end of its life cycle and can be replaced, avoiding health problems caused by long-term use. The printing dye of this application does not need to be pasted as a printed icon but is directly printed on the textile, avoiding the problem of shedding during the washing process and will not affect the textile fibers.

[0031] 3. This application realizes the control of fading / discoloration cycle by combining microcapsules of different concentrations and different shell material mechanical properties with different disperse dyes. The printing dye of this application is used as a printing icon, and the color changes significantly after 30 cycles of washing and sun exposure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0033] Figure 1 Schematic diagram of the structure of the microcapsules prepared in the examples of this application.

[0034] Figure 2 This is an electron microscope image of the microcapsules prepared in Example 1 of the present application.

[0035] Figure 3 This is a cross-sectional SEM image of a printed icon made with the printing dye of Example 1 of the present application.

[0036] Figure 4 This is a schematic diagram of the printed icon made of the printing dye of Example 1 of the present application before and after simulating 30 washing and sun-drying cycles.

[0037] Figure 5 This is a schematic diagram of the color change process of a printed icon made of the printing dye of Example 1 of the present application after simulating 30 washing and sun-drying cycles. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0039] The embodiments of the present application provide a photochromic printing dye, which can solve the problem in the prior art that color-changing labels are easily detached when affixed to textiles.

[0040] The present invention provides a method for preparing a photochromic printing dye, comprising the following steps:

[0041] Step S101: using a high-speed shearing dispersing disk to fully disperse a disperse dye in an organic continuous phase at room temperature to obtain a disperse dye solution; the disperse dye is selected from indigo dye, anthraquinone dye, or triarylmethane dye; the organic continuous phase is selected from any one of ethylene glycol, 1,2-propylene glycol, and glycerol; and the weight ratio of the disperse dye to the organic continuous phase is 1:5 to 1:15;

[0042] Step S102, at room temperature, adding an anti-settling agent to the disperse dye solution, fully dissolving it, then adding microcapsules and uniformly dispersing it to obtain a photochromic printing dye; the mass concentration of the microcapsules in the photochromic printing dye is 2‰ to 2%; the anti-settling agent is a mixture of one or more of organic montmorillonite, polyethylene wax, and a nonionic surfactant; the mass concentration of the anti-settling agent in the photochromic printing dye is 1‰ to 1%.

[0043] In step S102, the preparation process of the microcapsules is as follows: adding hydrophilic mesoporous nano-SiO2 to the oxidant solution, vacuuming the oxidant solution to completely adsorb it onto the nano-SiO2 particles, and the amount of hydrophilic mesoporous nano-SiO2 used is 10% to 30% of the mass of the oxidant solution; adding an organic solvent to the emulsifier to fully dissolve it to obtain an oil phase solution; adding the nano-SiO2 particles that adsorbed the oxidant solution to the oil phase solution, stirring at a speed of 500 to 2000 rpm to obtain an emulsion with uniform particle size; adding the shell material solution to the emulsion, adding an alkaline solution to adjust the pH value to 7 to 10, reacting at 30 to 60°C for 5 to 12 hours, filtering, washing, and drying after the reaction is completed to obtain microcapsules. The structural diagram of the microcapsules is shown in FIG. Figure 1 , Figure 1 In the figure, 10 represents the core material oxidant solution, 20 represents the inner layer SiO2 shell material, and 30 represents the outer layer shell material.

[0044] The oxidant is selected from any one of sodium ferrate, ferrous sulfate, polyferric sulfate, sodium hypochlorite, aluminum trifluoride or periodic acid; the organic solvent is selected from a mixture of one or more of n-hexane, cyclohexane, toluene, xylene and ether; the emulsifier is selected from a mixture of one or more of Tween-80, polyvinyl alcohol, OP-10, styrene-maleic anhydride copolymer, sodium dodecylbenzenesulfonate and sodium lauryl sulfate; the shell material is a mixture of one or more of tetraethyl orthosilicate, tetrabutyl titanate, KH550, KH560 and KH570; the alkaline solution is selected from any one of sodium hydroxide, potassium hydroxide, calcium hydroxide and triethanolamine; in the oxidant solution, the mass ratio of the oxidant to deionized water is 0.5 to 3; the amount of the emulsifier added is 1% to 5% of the mass of the oxidant solution; and the amount of the shell material added is 0.5 to 2 times the mass of the oxidant solution.

[0045] Example 1:

[0046] Preparation of microcapsules: fully dissolve ferrous sulfate in deionized water to obtain a ferrous sulfate solution, wherein the mass ratio of ferrous sulfate to deionized water is 1:1; add hydrophilic mesoporous nano-SiO2 to the ferrous sulfate solution, and vacuumize the ferrous sulfate solution to completely adsorb the nano-SiO2 particles, wherein the amount of hydrophilic mesoporous nano-SiO2 is 20% of the mass of the ferrous sulfate solution; add emulsifier OP-10 to n-hexane and fully dissolve it to obtain an oil phase solution, wherein the amount of emulsifier OP-10 added is 3% of the mass of the ferrous sulfate solution. ; Add nano-SiO2 particles adsorbed with ferrous sulfate solution to the oil phase, and obtain an emulsion with uniform particle size at a rotation speed of 1000 rpm; then add ethyl orthosilicate and KH560 to the emulsion, the mass ratio of ethyl orthosilicate to KH560 is 3:1, and the amount of ethyl orthosilicate and KH560 added is 1 times the mass of ferrous sulfate solution; add sodium hydroxide to adjust the pH value of the solution to 9, react at 40°C for 8 hours, then filter, wash, and dry to obtain microcapsules with a particle size of 2 to 8 μm; the electron microscope spectrum of the microcapsules is shown in Figure 2 ,from Figure 2 It can be seen that the prepared microcapsules are uniform in size and densely coated.

[0047] Preparation of a photochromic printing dye: at room temperature, using a high-speed disperser, dispersing a basic violet dye in glycerol, wherein the mass ratio of basic violet to glycerol is 1:10; adding organic montmorillonite to the dispersion at room temperature; adding the dispersion to a kneader, adding microcapsules at room temperature and uniformly dispersing the dispersion to obtain the photochromic printing dye; wherein the mass concentration of the organic montmorillonite in the photochromic printing dye is 0.3%, and the mass concentration of the microcapsules in the photochromic printing dye is 2%.

[0048] The photochromic printing dye prepared in Example 1 was mixed evenly with the screen printing paste in a mass ratio of 1:20, screen printed and transferred onto the cloth, and dried to obtain a sample. The electron microscope spectrum of the screen printed sample is shown in FIG. Figure 3 ,from Figure 3 It can be seen that the microcapsules are uniformly dispersed in the slurry and have good compatibility with the slurry.

[0049] The comparison of the screen printing sample prepared in Example 1 before and after 30 simulated water washing and sun exposure cycles is shown in the figure below: Figure 4 As shown, the color change process is as follows Figure 5 As shown. Figure 4 and Figure 5 It can be seen that after washing and sun exposure, the color of the screen printed sample faded linearly from purple to lavender.

[0050] Example 2:

[0051] Preparation of microcapsules: Sodium ferrate is fully dissolved in deionized water to obtain a sodium ferrate solution, wherein the mass ratio of sodium ferrate to deionized water is 2:1; hydrophilic mesoporous nano-SiO2 is added to the sodium ferrate solution, and vacuum is applied to completely adsorb the sodium ferrate solution onto the nano-SiO2 particles, wherein the amount of hydrophilic mesoporous nano-SiO2 is 25% of the mass of the sodium ferrate solution; Tween-80 is added to cyclohexane and fully dissolved to form an oil phase solution, wherein the amount of Tween-80 added is 1:1 of the sodium ferrate solution. The emulsion is prepared by adding nano-SiO2 particles adsorbed with sodium ferrate solution to the oil phase, and the mixture is stirred at 1000 rpm to obtain an emulsion with uniform particle size. Tetrabutyl titanate and KH560 are then added to the emulsion, with the mass ratio of tetrabutyl titanate to KH560 being 3:1, and the amount of tetrabutyl titanate and KH560 added being 0.8 times the mass of the sodium ferrate solution. Sodium hydroxide is added to adjust the pH value of the solution to 9, and the mixture is reacted at 45°C for 10 hours, followed by filtration, washing, and drying to obtain microcapsules.

[0052] Preparation of photochromic printing dye: Indigo dye is dispersed in glycerol using a high-speed disperser at room temperature, wherein the mass ratio of indigo dye to glycerol is 1:8; polyethylene wax is added to the dispersion at room temperature; the dispersion is added to a kneader, and microcapsules are added and uniformly dispersed at room temperature to obtain the photochromic printing dye; wherein the mass concentration of the polyethylene wax in the photochromic printing dye is 0.5%, and the mass concentration of the microcapsules in the photochromic printing dye is 1%.

[0053] The photochromic printing dye prepared in Example 2 was evenly mixed with the screen printing paste in a mass ratio of 1:20, screen-printed and transferred onto fabric, and dried to obtain a sample.

[0054] The screen-printed sample prepared in Example 2 was subjected to 30 cycles of washing and sun exposure testing, and its color changed from initial purple to pink through linear fading.

[0055] Example 3:

[0056] Preparation of microcapsules: Sodium hypochlorite is fully dissolved in deionized water to obtain a sodium hypochlorite solution, wherein the mass ratio of sodium hypochlorite to deionized water is 1.5:1; hydrophilic mesoporous nano-SiO2 is added to the sodium hypochlorite solution, and vacuum is applied to completely adsorb the sodium hypochlorite solution onto the nano-SiO2 particles, wherein the amount of hydrophilic mesoporous nano-SiO2 is 20% of the mass of the sodium hypochlorite solution; sodium lauryl sulfate is added to ether and fully dissolved to form an oil phase solution, wherein the amount of sodium lauryl sulfate added is 2.5% of the mass of the sodium hypochlorite solution; the nano-SiO2 particles adsorbing the sodium hypochlorite solution are added to the oil phase, and an emulsion with uniform particle size is obtained at a speed of 1500 rpm; KH570 is then added to the emulsion, and the amount of KH570 added is 0.5 times the mass of the sodium hypochlorite solution; sodium hydroxide is added to adjust the pH value of the solution to 9, and the reaction is carried out at 50°C for 8 hours, followed by filtration, washing, and drying to obtain microcapsules;

[0057] Preparation of photochromic printing dye: Malachite green is dispersed in ethylene glycol using a high-speed disperser at room temperature, wherein the mass ratio of malachite green to ethylene glycol is 1:8; epoxy diacetate POD is added to the dispersion at room temperature; the dispersion is added to a kneader, and microcapsules are added and uniformly dispersed at room temperature to obtain the photochromic printing dye; wherein the mass concentration of epoxy diacetate POD in the photochromic printing dye is 0.3%, and the mass concentration of the microcapsules in the photochromic printing dye is 1.2%.

[0058] The photochromic printing dye prepared in Example 3 was evenly mixed with the screen printing paste in a mass ratio of 1:20, screen-printed and transferred onto fabric, and dried to obtain a sample.

[0059] The screen-printed sample prepared in Example 3 was subjected to 30 cycles of washing and sun exposure, and its color faded linearly from green to light yellow.

[0060] Example 4:

[0061] Preparation of microcapsules: fully dissolve periodic acid in deionized water to obtain a periodic acid solution, wherein the mass ratio of periodic acid to deionized water is 1:1; add hydrophilic mesoporous nano-SiO2 to the periodic acid solution, and evacuate the solution to completely adsorb the periodic acid solution onto the nano-SiO2 particles, wherein the amount of hydrophilic mesoporous nano-SiO2 used is 18% of the mass of the periodic acid solution; add sodium dodecylbenzenesulfonate to n-hexane and fully dissolve it to form an oil phase solution, wherein the amount of sodium dodecylbenzenesulfonate added is 3% of the mass of the periodic acid solution; add the nano-SiO2 particles adsorbing the periodic acid solution to the oil phase, and obtain an emulsion with uniform particle size at a speed of 1000 rpm; then add KH550 to the emulsion, and the amount of KH550 added is 1 times the mass of the periodic acid solution; add potassium hydroxide to adjust the pH value of the solution to 9, react at 55°C for 8 hours, and then filter, wash, and dry to obtain microcapsules;

[0062] Preparation of photochromic printing dye: at room temperature, using a high-speed disperser, dispersing dye fuchsin in glycerol, wherein the mass ratio of fuchsin to glycerol is 1:12; at room temperature, adding organic montmorillonite to the dispersion; adding the dispersion to a kneader, adding microcapsules at room temperature and uniformly dispersing the dispersion to obtain the photochromic printing dye; wherein the mass concentration of the organic montmorillonite in the photochromic printing dye is 0.6%, and the mass concentration of the microcapsules in the photochromic printing dye is 5‰.

[0063] The photochromic printing dye prepared in Example 4 was evenly mixed with the screen printing paste in a mass ratio of 1:20, screen-printed and transferred onto fabric, and dried to obtain a sample.

[0064] The screen printing sample prepared in Example 4 was tested after 30 cycles of washing and sun exposure, and its color faded linearly from red to light yellow.

[0065] Example 5:

[0066] Preparation of microcapsules: fully dissolve polyferric sulfate in deionized water to obtain polyferric sulfate solution, the mass ratio of polyferric sulfate to deionized water is 2:1; add hydrophilic mesoporous nano-SiO2 to the polyferric sulfate solution, vacuumize the polyferric sulfate solution to completely adsorb it onto the nano-SiO2 particles, the amount of hydrophilic mesoporous nano-SiO2 is 15% of the mass of the polyferric sulfate solution; add emulsifier OP-10 to n-hexane and fully dissolve it to obtain an oil phase solution, wherein the amount of emulsifier OP-10 added is 15% of the mass of the polyferric sulfate solution. The method comprises the following steps: adding nano-SiO2 particles adsorbed with the polyferric sulfate solution to the oil phase, and rotating the mixture at 1800 rpm to obtain an emulsion with uniform particle size; then adding ethyl orthosilicate and KH570 to the emulsion, wherein the mass ratio of ethyl orthosilicate to KH570 is 3:1, and the amount of ethyl orthosilicate and KH570 added is 1.2 times the mass of the polyferric sulfate solution; adding triethanolamine to adjust the pH value of the solution to 9, reacting at 60°C for 8 hours, and then filtering, washing, and drying to obtain microcapsules;

[0067] Preparation of photochromic printing dye: at room temperature, using a high-speed disperser to disperse the dye methyl violet in 1,2-propylene glycol, wherein the mass ratio of methyl violet to 1,2-propylene glycol is 1:15; at room temperature, polyethylene wax is added to the dispersion; the dispersion is added to a kneader, and microcapsules are added and uniformly dispersed at room temperature to obtain the photochromic printing dye; wherein the mass concentration of the polyethylene wax in the photochromic printing dye is 8‰, and the mass concentration of the microcapsules in the photochromic printing dye is 1.5%.

[0068] The photochromic printing dye of Example 5 was evenly mixed with the screen printing paste in a mass ratio of 1:20, screen-printed and transferred onto fabric, and dried to obtain a sample.

[0069] The screen-printed sample prepared in Example 5 was subjected to 30 cycles of washing and sun exposure, and its color faded linearly from purple to light pink.

[0070] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0071] It should be noted that, in the present application, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements. In the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly specified.

[0072] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A photochromic printing dye, characterized in that: The invention is obtained by dispersing disperse dye and microcapsules in an organic continuous phase. The disperse dye is an anthraquinone dye. The core material of the microcapsule is an oxidant, which is any one of sodium ferrate, sodium hypochlorite or periodic acid. The shell material of the microcapsule is a SiO2 complex.

2. The photochromic printing dye according to claim 1, characterized in that The organic continuous phase is any one of ethylene glycol, 1,2-propylene glycol, and glycerol.

3. The photochromic printing dye according to claim 1, characterized in that The weight ratio of the disperse dye to the organic continuous phase is 1:5 to 1:15; the mass concentration of the microcapsules in the photochromic printing dye is 2‰ to 2%.

4. The method for preparing the photochromic printing dye according to claim 1, characterized in that: The following steps are involved: S101, fully dispersing a disperse dye in an organic continuous phase at room temperature to obtain a disperse dye solution; S102, adding an anti-settling agent to the disperse dye solution at room temperature and fully dissolving it, then adding microcapsules and uniformly dispersing them to obtain a photochromic printing dye.

5. The method for preparing the photochromic printing dye according to claim 4, wherein: The microcapsules are prepared by the following process: Add hydrophilic mesoporous nano-SiO2 into the oxidant solution, and evacuate the solution to completely adsorb the oxidant solution onto the nano-SiO2 particles; Adding an organic solvent to the emulsifier and fully dissolving it to obtain an oil phase solution; Adding the nano-SiO2 particles adsorbing the oxidant solution into the oil phase solution and stirring to obtain an emulsion with uniform particle size; The shell material solution is added to the emulsion, and then an alkaline solution is added to adjust the pH value to 7-10, and the reaction is carried out at 30-60° C. After the reaction is completed, the microcapsules are obtained by filtering, washing and drying.

6. The method for preparing the photochromic printing dye according to claim 5, characterized in that: The organic solvent is a mixture of one or more of n-hexane, cyclohexane, toluene, xylene, and ether; the emulsifier is a mixture of one or more of Tween-80, polyvinyl alcohol, OP-10, styrene-maleic anhydride copolymer, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate.

7. The method for preparing the photochromic printing dye according to claim 5, characterized in that: The shell material solution is a mixture of one or more of ethyl orthosilicate, tetrabutyl titanate, KH550, KH560, and KH570; and the alkaline solution is any one of sodium hydroxide, potassium hydroxide, calcium hydroxide, and triethanolamine.

8. The method for preparing the photochromic printing dye according to claim 5, wherein: The added amount of the emulsifier is 1% to 5% of the mass of the oxidant solution; and the added amount of the shell material is 0.5 to 2 times the mass of the oxidant solution.

9. The method for preparing the photochromic printing dye according to claim 4, wherein: The anti-settling agent is a mixture of one or more of organic montmorillonite, polyethylene wax and non-ionic surfactant; the mass concentration of the anti-settling agent in the photochromic printing dye is 1‰ to 1%.

10. The photochromic printing dye prepared by the preparation method according to any one of claims 4 to 9 is added to screen printing paste, screen thermal transfer paste or inkjet thermal transfer paste for printing textiles.

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