Photochromic agents, photochromic anti-counterfeiting silicone adhesives, and methods of making and using the same

Abstract

The application discloses a photochromic agent, a photochromic anti-fake silicone adhesive and a preparation method and application thereof, and belongs to the technical field of high polymer materials. The photochromic agent contains (CH2)n-SiR"3 in a molecular structure, has good compatibility and stability in the silicone adhesive, solves the delamination and influence on discoloration caused by poor compatibility of the photochromic agent with the system, and does not have a negative influence on the transparency and mechanical properties of the sealant itself. The photochromic agent has a fast discoloration speed, appears discoloration within 3s after ultraviolet treatment, the color becomes deeper with the extension of irradiation time, and finally reaches stability. When the ultraviolet irradiation is finished, the color of the photochromic agent slowly disappears, the color can be accelerated to disappear by using a daylight lamp to color, and the photochromic agent has excellent reversibility (i.e. discoloration under ultraviolet irradiation, and gradually returns to a colorless and transparent state by removing the ultraviolet source or irradiating with white light).

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high molecular materials, in particular to a photochromic agent, a photochromic anti-counterfeiting silicone sealant and a preparation method and application thereof. BACKGROUND

[0002] Silicone sealant can be used as adhesive, sealant and potting agent, etc., and has good bonding effect on materials such as metal, glass, doors and windows, and is widely used in the fields of curtain wall, building, electronic and electrical appliances, automobile, aviation, etc., and is an indispensable material for sealing and bonding in daily life. With the continuous development of the silicone sealant market, counterfeit and inferior silicone sealant products frequently appear, with uneven quality, and consumers have difficulty in accurately identifying the authenticity of the products. For quality problems that occur during use, manufacturers have difficulty in identifying their own products through effective means and effectively handling consumer complaints, making it difficult for consumers and manufacturers to maintain their own rights and interests. Therefore, it is necessary to develop anti-counterfeiting silicone sealant, which is of great significance for the identification, quality assurance, consumer rights protection and market stability of silicone sealant.

[0003] Photochromic materials have significant advantages in remote control, instantaneity, signal stability and environmental protection due to their specific photochromic properties, and are widely used in many fields such as information storage, light control devices, security and anti-counterfeiting technology, decoration, etc. Light-stimulated responsive molecules will change their structure under specific wavelength light, sometimes accompanied by a change in color on a macro scale. Under another wavelength of light or in the dark, the molecular structure will return to its original structure, and the color will also fade.

[0004] Most of the commonly used organic photochromic compounds are spiro-pyrans, azobenzenes, spiro-oxazines, fulgides, diarylethene, etc., but not all of them are suitable for developing anti-counterfeiting silicone sealant. The compatibility and stability of photochromic compounds with silicone sealant also need to be considered to ensure that the addition of photochromic compounds will not affect the bonding performance and appearance effect of the sealant. In addition, the production cost of the manufacturer also needs to be considered, so that the photochromic anti-counterfeiting function is achieved while also having certain economic benefits. Therefore, selecting the appropriate organic photochromic agent and reasonable component configuration is very important for obtaining reversible photochromic anti-counterfeiting silicone sealant.

[0005] Patent CN104974710A discloses a dealcoholization type anti-fake silicone sealant, which achieves the effect of anti-fake by adding a photochromic agent in the dealcoholization type silicone sealant, but the photochromic agent is an inorganic metal compound, such as a transition metal oxide, a metal halide, a rare earth complex, etc. However, such photochromic agent has the following disadvantages: 1. slow photochromic response speed; 2. poor reversibility of color change; 3. limited color change range; 4. limited application in transparent glue, which affects the transparency; 5. when used in sealant, the mechanical properties of the sealant are reduced due to the large particle size.

[0006] Patent CN 108913062A discloses a photosensitive color-changing environmentally friendly sealant and a preparation method thereof, which realizes color change by adding a photosensitive color-changing powder in the environmentally friendly sealant. The color-changing powder includes spiropyrans, a rohun voice, azo compounds, etc. It further discloses that the coupling agent is at least one of gamma-aminopropyl triethoxysilane, gamma-(2,3-epoxypropoxy) propyl trimethoxysilane, and N-beta-aminoethyl-gamma-aminopropyl trimethoxysilane; the spiropyrans are in a closed ring state under no light and present no color; when irradiated by a specific wavelength of light, the spiropyrans will undergo photochromism and change from colorless to colored state. The silane coupling agent in the silicone sealant is alkaline, and in the preparation of the sealant with spiropyrans as photosensitizer, the first few steps can normally change color. However, after adding the coupling agent containing amino group in the last step, the sealant presents yellow color and does not have the color change function. This is because the addition of amino group will affect the stability of spiropyrans, and the spiropyrans are prone to ring-opening reaction, so that the proportion of ring-opening state spiropyrans increases. Under this condition, the ring-opening state spiropyrans usually present yellow color, so the yellowing phenomenon is observed after mixing.

[0007] In view of this, the present application is proposed. SUMMARY

[0008] The purpose of the present application is to overcome the deficiencies in the prior art and provide a photochromic agent, a photochromic anti-fake silicone glue, and a preparation method and application thereof. The photochromic agent has good compatibility and stability in the silicone glue, solves the delamination and influence on color change caused by poor compatibility of the photochromic agent with the system, and does not have negative effects on the transparency and mechanical properties of the sealant itself.

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

[0010] A photochromic agent, the structural formula of which is shown as formula I:

[0011]

[0012] In formula I, R' is selected from one of hydrogen, methyl or phenyl, R'' is selected from one of methoxy, ethoxy, butanone oxime; n is an integer greater than or equal to 1.

[0013] The photochromic agent has a molecular structure containing (CH2)n-SiR''3, has good compatibility and stability in a silicone glue, solves delamination and influence on discoloration caused by poor compatibility of the photochromic agent with the system, and does not have a negative influence on the transparency and mechanical properties of the sealant itself.

[0014] The photochromic agent has a molecular structure containing (CH2)n-SiR''3, and the introduction of the (CH2)n-SiR''3 structure ensures original properties of the sealant and excellent weather resistance, and the sealant can still quickly discolor in response after salt spray, high temperature and high temperature and high humidity treatment, and has excellent anti-aging performance.

[0015] The application further provides a preparation method of the photochromic agent, including the following steps:

[0016] (1) reacting compound 1 and tributyl borate in the presence of a first solvent and a first catalyst, extracting, washing the aqueous phase, filtering, and drying to obtain compound 2;

[0017] (2) heating and refluxing the modifier and compound 2 in the presence of a second solvent, a second catalyst and a pH regulator, extracting, and drying the organic phase to obtain compound 3;

[0018] (3) reacting compound 3 and perfluorocyclopentene in the presence of a third solvent and a third catalyst, extracting, and drying the organic phase to obtain the photochromic agent;

[0019] The structural formula of compound 1 is as follows:

[0020]

[0021] R' in compound 1 is selected from one of hydrogen, methyl or phenyl.

[0022] The structural formula of the modifier is as follows:

[0023]

[0024] wherein R" in the modifier is selected from one of methoxy, ethoxy, butanone oxime; n is an integer ≥ 1.

[0025] wherein the reaction process involved in the photochromic agent of the present application is shown as follows:

[0026]

[0027] As a preferred embodiment of the present application, the molar ratio of the compound 1 and tributyl borate is 1: (0.8-1.2).

[0028] As a preferred embodiment of the present application, the molar ratio of the modifier and compound 2 is 1: (0.8-1.2).

[0029] As a preferred embodiment of the present application, the molar ratio of the compound 3 and perfluorocyclopentene is 1: (1.8-2.2).

[0030] As a preferred embodiment of the present application, the first solvent, the second solvent, and the third solvent are each independently selected from at least one of diethyl ether, dimethyl ether, dipropyl ether, tetrahydrofuran, 2-methyltetrahydrofuran.

[0031] As a preferred embodiment of the present application, the first catalyst and the third catalyst are each independently selected from at least one of n-butyllithium, neodecanoic acid neodymium, bismuth naphthenate, diethylaluminum chloride, dibutyltin dilaurate, stannous octoate, and dimorpholine diethyl ether.

[0032] As a preferred embodiment of the present application, the second catalyst is selected from at least one of tetrakis(triphenylphosphine)palladium and tetrakis(triphenylphosphine)platinum.

[0033] As a preferred embodiment of the present application, the reaction temperature in step (1) is 20-50°C, and the reaction time is 1-3h.

[0034] As a preferred embodiment of the present application, the heating reflux reaction time is 16-20h; and / or

[0035] As a preferred embodiment of the present application, the reaction temperature in step (3) is 20-50°C, and the reaction time is 1-3h.

[0036] It should be noted that in the preparation method of the photochromic agent of the present application, the usage amount of the catalyst (including the first catalyst, the second catalyst, and the third catalyst) and the solvent (including the first solvent, the second solvent, and the third solvent) is not limited, and those skilled in the art can adjust the usage amount of the catalyst and the solvent according to the conventional technical means in the art, wherein the solvent is sufficient to provide a reaction environment, and the catalyst is sufficient to catalyze the reaction.

[0037] The molar ratio of the compound 1 to the first catalyst is 1:(0.1-2).

[0038] The mass ratio of the compound 1 to the first solvent is 1:(4-100).

[0039] The step (1) can be terminated by adding dilute hydrochloric acid solution (0.1-1 mol / L) according to the situation.

[0040] The mass ratio of the compound 2 to the second solvent is 1:(4-100).

[0041] The molar ratio of the compound 2 to the second catalyst is 1:(0.01-0.1).

[0042] The pH regulator is sodium carbonate solution with a molar concentration of 1.5-2.5 mol / L.

[0043] The pH is adjusted to 9-11 by adding the pH regulator.

[0044] The molar ratio of the compound 3 to the third catalyst is 1:(0.1-2).

[0045] The mass ratio of the compound 3 to the third solvent is 1:(4-100).

[0046] The application further provides an application of the photochromic agent in preparing silicone glue.

[0047] The application further provides a photochromic anti-fake silicone glue, which comprises the following components in parts by weight: 100 parts of hydroxyl-terminated polydimethylsiloxane, 1-30 parts of plasticizer, 10-25 parts of filler, 5-10 parts of crosslinking agent, 0.5-2 parts of coupling agent, 0.05-0.1 part of catalyst and 0.001-1.5 parts of photochromic agent.

[0048] The photochromic agent comprises the photochromic agent described above.

[0049] In the specific silicone adhesive system of the present application, the photochromic agent has excellent compatibility and stability, solves the delamination and the influence on the discoloration caused by the poor compatibility of the photochromic agent with the system, and does not have a negative impact on the transparency and mechanical properties of the sealant itself. The photochromic agent has a fast photochromic speed, and after UV treatment, the discoloration occurs within 3s. With the extension of the irradiation time, the color becomes deeper and eventually reaches stability. When the UV irradiation is over, the color gradually disappears. The color can be accelerated to disappear by using a daylight lamp to color, and the photochromic agent has excellent reversibility (i.e. discoloration under UV light, and gradually returns to the colorless transparent state by removing the UV light source or irradiating with white light).

[0050] As a preferred embodiment of the present application, the amount of the photochromic agent is 0.05-0.5 parts.

[0051] As a preferred embodiment of the present application, the components include the following parts by weight: 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of plasticizer, 15-20 parts of filler, 6-8 parts of crosslinking agent, 1-1.5 parts of coupling agent, 0.06-0.08 parts of catalyst, and 0.1-0.13 parts of photochromic agent.

[0052] As a preferred embodiment of the present application, the viscosity of the hydroxyl-terminated polydimethylsiloxane at 25°C is 10000-200000 mpa·s.

[0053] The plasticizer is dimethyl silicone oil, and the viscosity of the dimethyl silicone oil at 25°C is 100-20000 mpa·s.

[0054] As a preferred embodiment of the present application, the crosslinking agent includes at least one of methyltrimethoxysilane or its oligomer, vinyltrimethoxysilane or its oligomer, propyltrimethoxysilane or its oligomer, methyl silicate, ethyl silicate, methyltris(butanone oxime)silane, vinyltris(butanone oxime)silane, dimethylbis(butanone oxime)silane, and tetrakis(butanone oxime)silane.

[0055] As a preferred embodiment of the present application, the coupling agent is a reactant of an amino silane coupling agent and an acrylate coupling agent.

[0056] The amino silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0057] The acrylate coupling agent includes at least one of γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, 3-(acryloyloxy)methyl dimethoxysilane, and 3-methacryloyloxypropyltriethoxysilane.

[0058] The molar ratio of the amino silane coupling agent to the acrylate coupling agent is 1:(0.8-1.2). The coupling agent is a reactant of the amino silane coupling agent and the acrylate coupling agent, the Michael addition reaction between the amino silane coupling agent and the acrylate effectively reduces the basicity of the amino silane coupling agent, so that the amino silane coupling agent does not affect the discoloration of the photochromic agent, while the adhesion of the amino silane coupling agent is retained. As a preferred embodiment of the present application, the filler is fumed silica, and the specific surface area of the fumed silica is 130-400 m 2 / g.

[0059] As a preferred embodiment of the present application, the catalyst includes at least one of dibutyltin dilaurate, dibutyltin diacetate, stannous octoate, dioctyltin dilaurate, and titanate.

[0060] The present application also provides a preparation method of the photochromic anti-fake silicone sealant, including the following steps:

[0061] The hydroxyl-terminated polydimethylsiloxane, the plasticizer, the crosslinking agent, and the photochromic agent are uniformly mixed, then the filler is uniformly mixed, and finally the coupling agent and the catalyst are uniformly mixed to obtain the photochromic anti-fake silicone sealant.

[0062] The present application also provides an application of the photochromic anti-fake silicone sealant in the fields of building curtain walls, metals, ceramics, plastics, doors and windows, rubber, electronic components, optical devices, rail transit, and automobiles.

[0063] The present application has the following beneficial effects: the photochromic agent has a molecular structure containing (CH2)n-SiR”3, which has good compatibility and stability in the silicone sealant, solves the delamination and the influence on discoloration caused by the poor compatibility of the photochromic agent with the system, and does not have a negative impact on the transparency and mechanical properties of the sealant itself, the photochromic agent has a fast photochromic speed, the discoloration occurs within 3s after ultraviolet treatment, the color becomes deeper with the extension of the irradiation time, and finally reaches stability, and the photochromic agent gradually disappears after the ultraviolet irradiation is stopped, the color disappears faster when colored by a daylight lamp, and has excellent reversibility (i.e., the color changes under ultraviolet irradiation, and gradually returns to the colorless and transparent state when the ultraviolet source is removed or irradiated by white light). DETAILED DESCRIPTION

[0064] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0065] In the present application, the technical features described in an open way include both a closed technical solution consisting of listed features and an open technical solution containing the listed features.

[0066] In the present application, if no special description is made, the numerical range is regarded as continuous and includes the minimum value and the maximum value of the range and each value between the minimum value and the maximum value. Further, when the range refers to an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a property, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0067] In the present application, the specific dispersion, stirring, filtration and extraction treatment methods are not particularly limited.

[0068] In addition, the terms "first", "second" are only used for description purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0069] The raw materials used in the examples and comparative examples are described as follows:

[0070] Hydroxyl-terminated polydimethylsiloxane: viscosity at 25°C is 80000 mPa·s, Xin'an Chemical, brand RTV-107-8.

[0071] Dimethyl silicone oil: viscosity at 25°C is 100 mPa·s. Brand 201-100.

[0072] Filler: fumed silica, specific surface area 180 m 2 / g, commonly commercially available.

[0073] Catalyst: dibutyl tin dilaurate, commonly commercially available.

[0074] Crosslinking agents: methyltributanone oxime silane and vinyltributanone oxime silane, mixed in a ratio of 4-8:1. For ease of comparison, all examples below use a mass ratio of 5:1, and are commercially available.

[0075] Coupling agent-1: The reaction product of γ-aminopropyltriethoxysilane and acrylate.

[0076] Coupling agent-2: The reaction product of γ-aminopropyltrimethoxysilane and acrylate.

[0077] The preparation methods for coupling agents-1 to-2 are as follows: In a 1000ml four-necked flask equipped with a stirrer, thermometer, reflux condenser, and dropping funnel, add 1 mol of γ-aminopropyltriethoxysilane (coupling agent-2 is γ-aminopropyltrimethoxysilane). Then, add 1 mol of γ-acryloyloxypropyltrimethoxysilane to the dropping funnel, slowly adding it dropwise over 3 hours. Slowly raise the temperature to 80℃ and continue the reaction for 5 hours, finally obtaining a pale yellow transparent liquid, which is the product.

[0078] Coupling agent-3: γ-aminopropyltriethoxysilane.

[0079] The preparation of photochromic agents 1 to 3 is as follows: (1) Compound 1 is dissolved in diethyl ether, and under nitrogen protection, n-butyllithium and tributyl borate are added. The reaction is carried out at 25°C for 1.5 h. The organic phase is extracted, the aqueous phase is washed until neutral, filtered, and dried to obtain compound 2. The molar ratio of compound 1, n-butyllithium and tributyl borate is 1:1:1.05.

[0080] (2) The modifier and tetra(triphenylphosphine)palladium were dissolved in tetrahydrofuran, compound 2 was added, the pH was adjusted to 10 with 2 mol / L sodium carbonate solution, the mixture was heated under reflux for 18 h, cooled to room temperature, extracted, and the organic phase was dried to obtain compound 3; wherein the molar ratio of modifier, compound 2 and tetra(triphenylphosphine)palladium was 1:1:0.05.

[0081] (3) Compound 3 was dissolved in tetrahydrofuran, and under nitrogen protection, n-butyllithium and perfluorocyclopentene were added. The mixture was reacted at 25°C for 1.5 h, extracted, and the organic phase was dried to obtain a photochromic agent. The molar ratio of compound 3, n-butyllithium, and perfluorocyclopentene was 1:1:2.

[0082] The structural formula of compound 1, which is used to prepare photochromic agent-1, is shown below:

[0083]

[0084] In compound 1 used to prepare photochromic agent-1, R' is hydrogen.

[0085] The structure of the modifier for preparing the photochromic agent-1 is shown as follows:

[0086]

[0087] In the modifier for preparing the photochromic agent-1, R" is methoxy; n is 1.

[0088] The structure of the compound 1 for preparing the photochromic agent-2 is shown as follows:

[0089]

[0090] In the compound 1, R' is hydrogen;

[0091] The structure of the modifier for preparing the photochromic agent-2 is shown as follows:

[0092]

[0093] In the modifier for preparing the photochromic agent-2, R" is ethoxy; n is 2.

[0094] The structure of the compound 1 for preparing the photochromic agent-3 is shown as follows:

[0095]

[0096] In the compound 1 for preparing the photochromic agent-3, R' is methyl;

[0097] The structure of the modifier for preparing the photochromic agent-3 is shown as follows:

[0098]

[0099] In the modifier for preparing the photochromic agent-3, R" is butanone oxime; n is 4.

[0100] Photochromic agent-4: The preparation method of the photochromic agent-4 is completely same as that of the photochromic agent-1, except that the modifier for preparing the photochromic agent-4 is different.

[0101] The structure of the modifier for preparing the photochromic agent-4 is shown as follows:

[0102]

[0103] Photochromic agent-5: Molybdenum trioxide.

[0104] Photochromic agent-6: Spiropyran.

[0105] Photochromic agent-7: 1,2-bis(2,5-dimethylthiophene-3-yl) perfluorocyclopentene.

[0106] The components and raw materials used in the embodiments and comparative examples of the present application are commercially available unless otherwise specified, and the components and raw materials used in each parallel experiment are the same.

[0107] Examples 1-7 and Comparative Examples 1-5

[0108] The formulations of the photochromic anti-counterfeiting silicone glue of Examples 1-7 and Comparative Examples 1-5 are shown in Table 1 (all in parts by weight).

[0109] The hydroxyl-terminated polydimethylsiloxane, plasticizer, crosslinking agent, and photochromic agent were mixed uniformly, then the filler was added and mixed uniformly, and finally the coupling agent and catalyst were added and mixed uniformly to obtain the photochromic anti-counterfeiting silicone glue.

[0110] Table 1

[0111]

[0112]

[0113] Performance test

[0114] (1) 100% modulus: tested according to the test method for tensile modulus in GB / T 13477.8-2017.

[0115] (2) Elongation: tested according to the method specified in 6.8.4 of GB / T 16776.

[0116] (3) Light transmittance / haze: the light transmittance and haze of the film were tested using a light transmittance instrument and recorded.

[0117] (4) Color change time: timing started from the beginning of irradiation of ultraviolet light until the appearance of color change.

[0118] (5) Color change time after 850: the film was placed in a high temperature and high humidity chamber at a temperature of 85°C and a humidity of 85% RH for 1000h, then taken out and placed at room temperature, and then timing was started.

[0119] Table 2

[0120]

[0121] As can be seen from Table 2, the photochromic anti-counterfeiting glue described in the present application has excellent mechanical properties, color change effect, and color change stability.

[0122] It can be seen from the comparative examples 1-4 that the silicone adhesive with better comprehensive performance can be obtained by controlling the amount of each raw material: 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of plasticizer, 15-20 parts of filler, 6-8 parts of crosslinking agent, 1-1.5 parts of coupling agent, 0.06-0.08 parts of catalyst and 0.1-0.13 parts of photochromic agent.

[0123] It can be seen from the comparative example 3 and comparative example 1 that the specific coupling agent used in the present application can significantly improve the mechanical properties and color changing effect.

[0124] It can be seen from the comparative example 3 and comparative examples 2-5 that the photochromic agent used in the present application can significantly improve the color changing effect and has excellent stability.

[0125] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A photochromic agent, characterized in that, Its structural formula is shown in Formula I: In Formula I, R' is selected from hydrogen or methyl, and R'' is selected from methoxy, ethoxy, and butanone oxime; n is an integer from 1 to 4.

2. The method for preparing the photochromic agent according to claim 1, characterized in that, Includes the following steps: (1) Compound 1 and tributyl borate were reacted in the presence of the first solvent and the first catalyst, extracted, washed, filtered and dried to obtain compound 2; (2) The modifier and compound 2 were heated under reflux in the presence of the second solvent, the second catalyst and the pH adjuster, extracted and dried to obtain compound 3; (3) Compound 3 and perfluorocyclopentene were reacted in the presence of a third solvent and a third catalyst, extracted, and the organic phase was dried to obtain a photochromic agent; The structural formula of compound 1 is shown below: In compound 1, R' is selected from either hydrogen or methyl; The structural formula of the modifier is shown below: In this modifier, R'' is selected from one of methoxy, ethoxy, or butanone oxime; n is an integer from 1 to 4.

3. The method for preparing the photochromic agent according to claim 2, characterized in that, The molar ratio of compound 1 to tributyl borate is 1:(0.8~1.2). The molar ratio of the modifier to compound 2 is 1:(0.8~1.2). The molar ratio of compound 3 to perfluorocyclopentene is 1:(1.8~2.2).

4. The method for preparing the photochromic agent according to claim 2, characterized in that, The first solvent, the second solvent, and the third solvent are each independently selected from at least one of diethyl ether, methyl ether, dipropyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran; The first catalyst and the third catalyst are each independently selected from at least one of the following: n-butyllithium, neodymium neodecanoate, bismuth naphthenate, diethylaluminum chloride, dibutyltin dilaurate, stannous octoate, and dimorpholine diethyl ether; The second catalyst is selected from at least one of tetra(triphenylphosphine)palladium and tetra(triphenylphosphine)platinum.

5. The method for preparing the photochromic agent according to claim 2, characterized in that, The reaction temperature in step (1) is 20~50℃ and the reaction time is 1~3h; The heating and reflux reaction in step (2) takes 16-20 hours; The reaction temperature in step (3) is 20~50℃ and the reaction time is 1~3h.

6. The use of the photochromic agent according to claim 1 in the preparation of silicone sealant.

7. A photochromic anti-counterfeiting silicone adhesive, characterized in that, It comprises the following components in parts by weight: 100 parts hydroxyl-terminated polydimethylsiloxane, 1-30 parts plasticizer, 10-25 parts filler, 5-10 parts crosslinking agent, 0.5-2 parts coupling agent, 0.05-0.1 parts catalyst, and 0.001-1.5 parts photochromic agent; The photochromic agent includes the photochromic agent according to claim 1.

8. The photochromic anti-counterfeiting silicone sealant according to claim 7, characterized in that, The viscosity of the hydroxyl-terminated polydimethylsiloxane at 25°C is 10,000~200,000 mPa·s. The plasticizer is dimethyl silicone oil, and the viscosity of the dimethyl silicone oil at 25°C is 100~20000 mpa·s.

9. The photochromic anti-counterfeiting silicone sealant according to claim 7, characterized in that, The crosslinking agent includes at least one of methyltrimethoxysilane or its oligomer, vinyltrimethoxysilane or its oligomer, propyltrimethoxysilane or its oligomer, methyl silicate, ethyl silicate, methyltributanone oxime silane, vinyltributanone oxime silane, dimethyldibutyl ketone oxime silane, and tetrabutyl ketone oxime silane. The coupling agent is a reaction product of an aminosilane coupling agent and an acrylate coupling agent. The aminosilane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane. The acrylate coupling agent includes at least one of γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, 3-(acryloyloxy)methyldimethoxysilane, and 3-methacryloyloxypropyltriethoxysilane.

10. The application of the photochromic anti-counterfeiting silicone sealant according to any one of claims 7 to 9 in building curtain walls, metals, ceramics, plastics, doors and windows, rubber, electronic components, optical devices, rail transportation, and automobiles.

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