A double-shell thermotropic reversible color-changing microcapsule, its preparation method, and its application.

Abstract

This application relates to the field of thermochromic materials technology, and particularly to a double-shell thermochromic reversible microcapsule, its preparation method, and its application. The double-shell thermochromic reversible microcapsule provided in this application includes a shell material and a core material. The shell material, from the inside out, consists of a cured epoxy resin and polymethyl methacrylate (PMMA), which are bonded together by a silane coupling agent. By weight, the core material includes 2-10 parts of a leucochromic agent, 6-16 parts of a chromogenic agent, 25-40 parts of a phase change material, and 1-2 parts of an antioxidant. The microcapsules prepared in this application have an enthalpy value of up to 190 KJ / KG and can withstand at least 200 thermal cycling experiments with an enthalpy decay of less than 5%.

Description

Technical Field

[0001] This application relates to the field of thermochromic materials technology, and in particular to a double-shell thermochromic reversible microcapsule, its preparation method, and its application. Background Technology

[0002] Thermochromic properties refer to the phenomenon of reversible or irreversible color changes in response to temperature variations. Thermochromic materials are functional materials in which the visible absorption spectrum changes when heated or cooled, exhibiting the characteristic of color change with temperature. As a class of smart materials with thermal memory function, thermochromic materials have been widely used in various fields such as anti-counterfeiting, temperature indication, textiles, and daily life.

[0003] Patent CN104877065B discloses a long-life, high-color-difference organic reversible thermochromic microcapsule and its preparation method. The wall material of the microcapsule is polymerized from 30-95% by weight of acrylate and / or methacrylate, 5-70% by weight of a mixture of divinyl and / or polyvinyl monomers, and 0-10% by weight of a mixture of acrylic acid and / or methacrylic acid. The core material is composed of a color-developing agent 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide, a color-developing agent 4,4′-dihydroxydiphenyl sulfone, and a solvent selected from 1-dodecanol, 1-tetradecanol, 1-hexadecanol, and 1-octadecanol. The wall material of the microcapsule has a single-layer structure and is easily swollen and ruptured in organic solvents such as toluene, xylene, and ethyl acetate.

[0004] Based on the above analysis, it is essential to provide a thermochromic microcapsule for wall materials that is resistant to organic solvents. Summary of the Invention

[0005] This application provides a double-shell thermochromic microcapsule to solve the problem of existing thermochromic microcapsules easily swelling and rupturing in organic solvents. The microcapsule provided in this application has a double-shell structure, which tightly encapsulates the thermochromic material, exhibits sensitive thermochromic changes, high fatigue resistance, and strong practicality.

[0006] In a first aspect, this application provides a double-shell thermotropic reversible color-changing microcapsule, comprising a shell material and a core material. The shell material consists of an epoxy resin cured product and polymethyl methacrylate from the inside out, and the epoxy resin cured product and polymethyl methacrylate are bonded together by a silane coupling agent. By weight, the core material comprises 2-10 parts of a leucochromic agent, 6-16 parts of a color-developing agent, 25-40 parts of a phase change material, and 1-2 parts of an antioxidant.

[0007] In some embodiments, the weight ratio of the shell material to the core material is 1:5 to 1:2.

[0008] In some embodiments, the color-developing agent is selected from crystal violet lactone, thermo red, thermo black, and thermo green; the structures of each color-developing agent are shown below:

[0009]

[0010] In some embodiments, the leucoant is selected from one or more of bisphenol A, bisphenol AF, and phthalimide; the phase change material is selected from one or more of n-tetradecyl alcohol, n-hexadecyl alcohol, n-octadecyl alcohol, n-docosahexane, methyl octadecanoate, ethyl octadecanoate, methyl docosahexanoate, and ethyl docosahexanoate.

[0011] In some embodiments, the antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant B225, and antioxidant DLTP, or a mixture thereof.

[0012] Secondly, this application also provides a method for preparing the above-mentioned double-shell thermotropic reversible color-changing microcapsules, including the following steps:

[0013] Step S101: The leucoant, color developer, phase change material and antioxidant are heated and dissolved to obtain a thermochromic material;

[0014] Step S102: The epoxy shell polymer and oil-based curing agent are dissolved in an organic solvent, and then the thermochromic material is added and mixed to obtain the oil phase;

[0015] Step S103: Homogenize and emulsify the oil phase and emulsifier to obtain an O / W type emulsion. Heat the emulsion to evaporate the solvent, and then add an aqueous curing agent to obtain a first mixed solution with a pH value of 9 to 10.

[0016] Step S104: Add silane coupling agent to the first mixed solution to obtain the second mixed solution;

[0017] In step S105, methyl methacrylate, phase transfer catalyst and initiator are added to the second mixed solution, and the reaction is continued by stirring. After the reaction is completed, the mixture is centrifuged, washed and dried to obtain double-shell thermochromic microcapsule powder.

[0018] In some embodiments, the heating temperature in step S101 is 150–200°C.

[0019] In some embodiments, the organic solvent is dichloromethane and / or ethyl acetate.

[0020] In some embodiments, the epoxy shell polymer includes at least one of bisphenol A type epoxy resin E44, bisphenol A type epoxy resin E51, phenolic epoxy resin F44, and phenolic epoxy resin F51.

[0021] In some embodiments, the oil-based curing agent is selected from one or more of m-phenylenediamine, 4,4'-diaminodiphenylmethane, and diaminodiphenyl sulfone; the water-based curing agent is selected from one or more of ethylenediamine (EDA), diethylenetriamine (DETA), tetraethylenepentamine (TEPA), and m-phenylenediamine.

[0022] In some embodiments, the emulsifier is selected from one or more of polyvinyl alcohol, sodium dodecylbenzene sulfonate, styrene-maleic anhydride, and Tween 80; the mass concentration of the emulsifier is 5%.

[0023] In some embodiments, the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0024] In some embodiments, the phase transfer catalyst is selected from one or more of benzyltriethylammonium chloride (TEBA), tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bisulfate (TBAB), trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, and tetradecyltrimethylammonium chloride.

[0025] In some embodiments, the initiator is selected from one or more of potassium persulfate, ammonium persulfate, benzoyl peroxide, or azobisisobutyronitrile.

[0026] In some embodiments, the mass fractions of each raw material are as follows: 180-250 parts emulsifier, 4-20 parts epoxy shell polymer, 2-5 parts oil-based curing agent, 2-10 parts water-based curing agent, 4-10 parts silane coupling agent, 2-10 parts methyl methacrylate, 0.2-1 parts phase transfer catalyst, and 0.1-0.5 parts initiator.

[0027] In some embodiments, in step S105, 4 to 10 parts by weight of isoprene tetraacrylate or trimethylolpropane triacrylate are added to the second mixed solution.

[0028] The double-shell thermochromic microcapsules provided in this application can be used to manufacture color-changing inks, temperature-sensitive indicator stickers, anti-counterfeiting coatings, thermochromic pens, etc.

[0029] The beneficial effects of the technical solution provided in this application include:

[0030] 1. The shell material of the microcapsule provided in this application is a double shell. The hydroxyl groups on the inner shell self-assemble with the silane coupling agent to the surface of the microcapsule through electrostatic interaction. Through hydrolysis, silanol is further generated, which dehydrates and condenses with the functional groups on the surface of the microcapsule to finally form a silane coupling agent modified microcapsule containing double bonds. This allows the surface of the microcapsule to carry more reactive groups. Then, methyl methacrylate is grafted onto the surface of the microcapsule through free radical polymerization. Under the impact of external force, the integrity of the capsule body can be maintained, protecting the core material from the external environment.

[0031] 2. The microcapsules prepared in this application have an enthalpy value of up to 190 KJ / KG and can withstand at least 200 thermal cycling experiments with an enthalpy value decay of less than 5%. Experiments show that the microcapsules prepared in this application can still maintain their morphology after being soaked in organic solvents toluene, xylene, and ethyl acetate for 24 hours. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the reaction process for preparing double-shell thermotropic reversible color-changing microcapsules according to an embodiment of this application;

[0034] Figure 2 This is a SEM image of the double-shell thermotropic reversible color-changing microcapsules prepared in Example 1 of this application;

[0035] Figure 3 This is a SEM image of the microcapsules prepared in Comparative Example 1 of this application in ethyl acetate. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] This application provides a double-shell thermochromic microcapsule that can solve the problems of existing thermochromic microcapsules in related technologies, such as easy swelling and rupture in organic solvents.

[0038] This application provides a method for preparing double-shell thermotropic reversible color-changing microcapsules, including the following steps:

[0039] Step S101: By mass, mix 2-10 parts of leucoant, 6-16 parts of color developer, 25-40 parts of phase change material and 1-2 parts of antioxidant, and melt-blend at a temperature of 150-200°C until a clear and transparent solution is obtained. After naturally cooling to room temperature, the thermochromic material can be obtained.

[0040] Step S102: By weight, 4-20 parts of epoxy shell polymer and 2-5 parts of oil-based curing agent are added to an organic solvent to dissolve, and then thermochromic material is added and mixed to obtain an oil phase;

[0041] Step S103: By weight, add 180-250 parts of an oil phase to a 5% emulsifier at 60-80℃ and stir at high speed to form an oil-in-water O / W emulsion; after emulsifying the oil-in-water O / W emulsion for 10 minutes, add 2-10 parts of an aqueous curing agent and continue stirring, then heat to evaporate the solvent in the emulsion to obtain the first mixed solution.

[0042] Step S104: Add 4 to 10 parts by mass of silane coupling agent to the first mixed solution to obtain the second mixed solution;

[0043] In step S105, by mass, 2-10 parts of methyl methacrylate, 0.2-1 parts of phase transfer catalyst and 0.1-0.5 parts of initiator are added to the second mixed solution. After stirring and reacting, the mixture is centrifuged, washed and dried at 60-80°C to obtain double-shell thermotropic reversible color-changing microcapsule powder.

[0044] The process for preparing the microcapsules in this application is described below. Figure 1 ,from Figure 1 It can be seen that the leucocyanate, color developer, phase change material and antioxidant are all encapsulated in the shell material. The outer layer of the shell material is polymethyl methacrylate, and the inner layer of the shell material is epoxy resin cured product. The epoxy resin cured product and polymethyl methacrylate are bonded together by a silane coupling agent.

[0045] The following describes in detail the double-shell thermotropic reversible color-changing microcapsules, their preparation method, and applications provided in this application, with reference to embodiments and comparative examples.

[0046] Example 1:

[0047] Example 1 provides a method for preparing bishell thermotropic reversible color-changing microcapsules, comprising the following steps:

[0048] (1) Weigh 7 parts crystal violet lactone, 3 parts bisphenol AF, 35 parts methyl octadecanoate and 2 parts antioxidant B225 by weight and mix them. Melt and blend them at 170°C until a clear and transparent solution is obtained. After naturally cooling to room temperature, the thermochromic material can be obtained.

[0049] (2) By mass, 15 parts of bisphenol A type epoxy resin E44 and 2 parts of m-phenylenediamine were added to ethyl acetate and dissolved, and then mixed with the thermochromic material obtained in step (1) as the oil phase.

[0050] (3) By mass, the oil phase solution was added to 200 parts of an aqueous solution (5% by mass) of styrene-maleic anhydride copolymer at 70°C and stirred at 2500 rpm for 20 min to form an oil-in-water O / W emulsion; after emulsifying the oil-in-water O / W emulsion for 10 min, 10 parts of ethylenediamine were added and stirring was maintained. The emulsion was heated to evaporate the solvent and obtain a first mixed solution with a pH of 9.

[0051] (4) Add 5 parts by mass of silane coupling agent KH-570 to the first mixed solution to obtain the second mixed solution;

[0052] (5) Add 7 parts of methyl methacrylate, 0.2 parts of tetrabutylammonium chloride and 0.2 parts of ammonium persulfate to the second mixed solution by mass, continue stirring, and then heat to 90-95℃ for 3-5 hours to allow it to be completely cross-linked and solidified. After the reaction is completed, cool down, centrifuge, wash and dry at 60℃ to obtain double-shell thermo-reversible color-changing microcapsule powder.

[0053] SEM image of the microcapsules prepared in Example 1 is shown below. Figure 2 ,from Figure 2 It can be seen that the microcapsule has a regular spherical shape.

[0054] The microcapsules prepared in Example 1 can achieve a reversible color change from blue to colorless under conditions of 31-32°C.

[0055] The microcapsules prepared in Example 1 have an enthalpy of 190 KJ / KG and can withstand at least 200 thermal cycles with an enthalpy decay of less than 5%.

[0056] The microcapsules prepared in Example 1 were soaked in organic solvents toluene, ethyl acetate, and xylene for 24 hours, respectively. Microscopic observation showed that the microcapsules still maintained their morphology.

[0057] Comparative Example 1:

[0058] Comparative Example 1 provides a method for preparing epoxy shell thermotropic reversible color-changing microcapsules, comprising the following steps:

[0059] (1) Weigh 7 parts crystal violet lactone, 3 parts bisphenol AF, 35 parts methyl octadecanoate and 2 parts antioxidant B225 by weight and mix them. Melt and blend them at 170°C until a clear and transparent solution is obtained. After naturally cooling to room temperature, the thermochromic material can be obtained.

[0060] (2) By mass, 15 parts of bisphenol A type epoxy resin E44 and 2 parts of m-phenylenediamine were added to ethyl acetate and dissolved, and then mixed with the thermochromic material obtained in step (1) as the oil phase.

[0061] (3) By mass, the oil phase solution was added to 200 parts of an aqueous solution (5% by mass) of styrene-maleic anhydride copolymer at 70°C and stirred at 2500 rpm for 20 min to form an oil-in-water O / W emulsion; after emulsifying the oil-in-water O / W emulsion for 10 min, 10 parts of ethylenediamine were added and stirring was maintained. The emulsion was heated to evaporate the solvent and obtain a mixed solution with a pH of 9.

[0062] (4) The mixed solution is heated to 90-95℃ and reacted for 3-5 hours to ensure complete cross-linking and curing. After the reaction is completed, the solution is cooled, filtered, washed, and dried at 60℃ to obtain epoxy shell material thermo-reversible color-changing microcapsules.

[0063] The SEM image of the microcapsules prepared in Comparative Example 1 in ethyl acetate is shown in Figure 1. Figure 3 ,from Figure 3 It can be seen that the morphology of the microcapsule has changed significantly, the color has disappeared, and the color cannot be restored after drying.

[0064] Example 2:

[0065] Example 2 provides a method for preparing bishell thermotropic reversible color-changing microcapsules, comprising the following steps:

[0066] (1) Weigh out 10 parts of Thermos Red, 4 parts of Bisphenol AF, 30 parts of n-octadecyl alcohol and 1.5 parts of antioxidant 168 by mass, mix them, melt and blend them at 160°C until a clear and transparent solution is obtained, and then cool them naturally to room temperature to obtain the thermochromic material.

[0067] (2) By mass, 16 parts of phenolic epoxy resin F51 and 4 parts of 4,4'-diaminodiphenylmethane were added to dichloromethane and dissolved, and then mixed with the thermochromic material obtained in step (1) as the oil phase;

[0068] (3) By mass, the oil phase solution was added to 185 parts of an aqueous solution of polyvinyl alcohol (5% by mass) at 70°C and stirred at 2000 rpm for 20 min to form an oil-in-water O / W emulsion; after the oil-in-water O / W emulsion was emulsified for 10 min, 3 parts of tetraethylenepentamine were added and stirring was maintained. The emulsion was heated to evaporate the solvent and obtain a first mixed solution with a pH of 10.

[0069] (4) Add 5 parts by mass of silane coupling agent KH-570 to the first mixed solution to obtain the second mixed solution;

[0070] (5) Add 5 parts of methyl methacrylate, 0.5 parts of trioctylmethylammonium chloride and 0.2 parts of potassium persulfate to the second mixed solution by mass, continue stirring, and then heat to 90-95℃ for 3-5 hours to allow it to be completely cross-linked and solidified. After the reaction is completed, cool down, centrifuge, wash, and dry at 70℃ to obtain double-shell thermo-reversible color-changing microcapsule powder.

[0071] The microcapsules prepared in Example 2 have an enthalpy of 183 KJ / KG and can withstand at least 200 thermal cycles with an enthalpy decay of less than 4%.

[0072] The microcapsules prepared in Example 2 were soaked in organic solvents toluene, xylene, and ethyl acetate for 24 hours, respectively. Microscopic observation showed that the microcapsules still maintained their morphology.

[0073] Example 3:

[0074] Example 3 provides a method for preparing bishell thermotropic reversible color-changing microcapsules, comprising the following steps:

[0075] (1) Weigh 12 parts of thermosensitive black, 4.5 parts of bisphenol AF, 38 parts of n-hexadecyl alcohol and 1 part of antioxidant DLTP by mass and mix them. Melt and blend them at 170°C until a clear and transparent solution is obtained. After naturally cooling to room temperature, the thermochromic material can be obtained.

[0076] (2) By weight, 18 parts of phenolic epoxy resin F44 and 3.5 parts of m-phenylenediamine were added to ethyl acetate and dissolved, and then mixed with the thermochromic material obtained in step (1) as the oil phase;

[0077] (3) By mass, the oil phase solution was added to 220 parts of Tween 80 aqueous solution (mass concentration 5%) at 70°C and stirred at 1800 rpm for 20 min to form an oil-in-water O / W emulsion; after the oil-in-water O / W emulsion was emulsified for 10 min, 6 parts of m-phenylenediamine were added and stirring was maintained. The emulsion was heated to evaporate the solvent and obtain a first mixed solution with a pH of 9.

[0078] (4) Add 7 parts by mass of silane coupling agent KH-570 to the first mixed solution to obtain the second mixed solution;

[0079] (5) Add 8 parts of methyl methacrylate, 0.6 parts of trioctylmethylammonium chloride and 0.3 parts of potassium persulfate to the second mixed solution by mass, continue stirring, and then heat to 90-95℃ for 3-5 hours to allow it to be completely cross-linked and solidified. After the reaction is completed, cool down, centrifuge, wash, and dry at 80℃ to obtain double-shell thermo-reversible color-changing microcapsule powder.

[0080] The microcapsules prepared in Example 3 have an enthalpy of 177 KJ / KG and can withstand at least 200 thermal cycling experiments with an enthalpy decay of less than 5%.

[0081] The microcapsules prepared in Example 3 were soaked in organic solvents toluene, xylene, and ethyl acetate for 24 hours, respectively. Microscopic observation showed that the microcapsules still maintained their morphology.

[0082] Example 4:

[0083] Example 4 provides a method for preparing bishell thermotropic reversible color-changing microcapsules, comprising the following steps:

[0084] (1) Weigh out 13.5 parts of thermosensitive green, 4 parts of phthalimide, 28 parts of methyl dodecanoate and 2 parts of antioxidant 1076 by mass, mix them, melt and blend them at 185°C until a clear and transparent solution is obtained, and then cool them naturally to room temperature to obtain the thermochromic material.

[0085] (2) By weight, 6 parts of phenolic epoxy resin F51 and 3 parts of diaminodiphenyl sulfone were added to ethyl acetate and dissolved, and then mixed with the thermochromic material obtained in step (1) as the oil phase.

[0086] (3) By mass, the oil phase solution was added to 180 parts of an aqueous solution of sodium dodecylbenzenesulfonate (mass concentration 5%) at 70°C and stirred at 2300 rpm for 20 min to form an oil-in-water O / W emulsion; after the oil-in-water O / W emulsion was emulsified for 10 min, 6 parts of ethylenediamine were added and stirring was maintained. The emulsion was heated to evaporate the solvent and obtain a first mixed solution with a pH of 9.

[0087] (4) Add 8 parts by mass of silane coupling agent KH-570 to the first mixed solution to obtain the second mixed solution;

[0088] (5) Add 4 parts of methyl methacrylate, 0.8 parts of dodecyltrimethylammonium chloride and 0.3 parts of ammonium persulfate to the second mixed solution by mass, continue stirring, and then heat to 90-95℃ for 3-5 hours to allow it to be completely cross-linked and solidified. After the reaction is completed, cool down, centrifuge, wash, and dry at 65℃ to obtain double-shell thermo-reversible color-changing microcapsule powder.

[0089] The microcapsules prepared in Example 4 have an enthalpy of 184 KJ / KG and can withstand at least 200 thermal cycling experiments with an enthalpy decay of less than 5%.

[0090] The microcapsules prepared in Example 4 were soaked in organic solvents toluene, xylene, and ethyl acetate for 24 hours, respectively. Microscopic observation showed that the microcapsules still maintained their morphology.

[0091] Example 5:

[0092] Example 5 provides a method for preparing double-shell thermotropic reversible color-changing microcapsules, comprising the following steps:

[0093] (1) Weigh out 14.5 parts of thermosensitive green, 5.5 parts of bisphenol A, 32 parts of methyl dodecanoate and 2 parts of antioxidant DLTP by mass, mix them, melt and blend them at 185°C until a clear and transparent solution is obtained, and then cool it naturally to room temperature to obtain the thermochromic material.

[0094] (2) By weight, 8 parts of phenolic epoxy resin F44 and 4.5 parts of diaminodiphenyl sulfone were added to ethyl acetate and dissolved, and then mixed with the thermochromic material obtained in step (1) as the oil phase;

[0095] (3) By mass, the oil phase solution was added to 180 parts of an aqueous solution of sodium dodecylbenzenesulfonate (mass concentration 5%) at 75°C and stirred at 2500 rpm for 20 min to form an oil-in-water O / W emulsion; after the oil-in-water O / W emulsion was emulsified for 10 min, 5 parts of ethylenediamine were added and stirring was maintained. The emulsion was heated to evaporate the solvent and obtain a first mixed solution with a pH of 9.

[0096] (4) Add 8 parts by mass of silane coupling agent KH-570 to the first mixed solution to obtain the second mixed solution;

[0097] (5) Add 4 parts of methyl methacrylate, 6 parts of isoprene tetraacrylate, 0.5 parts of dodecyltrimethylammonium chloride and 0.4 parts of ammonium persulfate to the second mixed solution by mass, continue stirring, and then heat to 90-95℃ for 3-5 hours to allow it to be completely cross-linked and solidified. After the reaction is completed, cool down, centrifuge, wash, and dry at 75℃ to obtain double-shell thermo-reversible color-changing microcapsule powder.

[0098] The microcapsules prepared in Example 5 have an enthalpy of 173 KJ / KG and can withstand at least 200 thermal cycles with an enthalpy decay of less than 5%.

[0099] The microcapsules prepared in Example 5 were soaked in organic solvents toluene, xylene, and ethyl acetate for 24 hours. Microscopic observation showed that the microcapsules still maintained their morphology.

[0100] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0101] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0102] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this 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 this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a double-shelled thermotropic reversible color-changing microcapsule, characterized in that, Includes the following steps: S101, a thermochromic material is obtained by heating and dissolving a leucochromic agent, a color developer, a phase change material and an antioxidant; wherein the mass parts of each raw material are: 2-10 parts of leucochromic agent, 6-16 parts of color developer, 25-40 parts of phase change material and 1-2 parts of antioxidant. S102, the epoxy shell polymer and oil-based curing agent are dissolved in an organic solvent, and then a thermochromic material is added and mixed to obtain an oil phase; the oil-based curing agent is selected from one or more of m-phenylenediamine, 4,4'-diaminodiphenylmethane, and diaminodiphenyl sulfone. S103, the oil phase and emulsifier are homogenized and emulsified to obtain an O / W type emulsion, then an aqueous curing agent is added and heated to obtain a first mixed solution; the aqueous curing agent is selected from one or more of ethylenediamine, diethylenetriamine, tetraethylenepentamine, and m-phenylenediamine. S104, a silane coupling agent is added to the first mixed solution to obtain a second mixed solution; the silane coupling agent is selected as γ-methacryloyloxypropyltrimethoxysilane. S105, add methyl methacrylate, phase transfer catalyst and initiator to the second mixed solution, continue stirring the reaction, after the reaction is completed, centrifuge, wash and dry to obtain double-shell thermochromic microcapsule powder.

2. The method for preparing the double-shell thermotropic reversible color-changing microcapsules according to claim 1, characterized in that, In step S101, the heating temperature is 150-200℃.

3. The method for preparing double-shell thermotropic reversible color-changing microcapsules according to claim 1, characterized in that, The organic solvent is dichloromethane and / or ethyl acetate; the epoxy shell polymer includes one or more of bisphenol A type epoxy resin E44, bisphenol A type epoxy resin E51, phenolic epoxy resin F44, and phenolic epoxy resin F51.

4. The method for preparing the double-shell thermotropic reversible color-changing microcapsules according to claim 1, characterized in that, The emulsifier is selected from one or more of polyvinyl alcohol, sodium dodecylbenzenesulfonate, styrene maleic anhydride and Tween 80; the initiator is selected from one or more of potassium persulfate, ammonium persulfate, benzoyl peroxide or azobisisobutyronitrile.

5. The method for preparing double-shell thermotropic reversible color-changing microcapsules according to claim 1, characterized in that, The phase transfer catalyst is selected from one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, and tetradecyltrimethylammonium chloride.

6. The method for preparing the double-shell thermotropic reversible color-changing microcapsules according to claim 1, characterized in that, The mass fractions of each raw material are as follows: emulsifier 180-250 parts, epoxy shell polymer 4-20 parts, oil phase curing agent 2-5 parts, water-based curing agent 2-10 parts, silane coupling agent 4-10 parts, methyl methacrylate 2-10 parts, phase transfer catalyst 0.2-1 parts, and initiator 0.1-0.5 parts.

7. The method for preparing the double-shell thermotropic reversible color-changing microcapsules according to claim 1, characterized in that, The color developer is selected from any one of crystal violet lactone, thermosensitive red, thermosensitive black, and thermosensitive green; the leucoant is selected from one or more of bisphenol A, bisphenol AF, and phthalimide; the phase change material is selected from one or more of n-tetradecyl alcohol, n-hexadecyl alcohol, n-octadecyl alcohol, n-docosahexane, methyl octadecanoate, ethyl octadecanoate, methyl docosahexanoate, and ethyl docosahexanoate; the antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant B225, and antioxidant DLTP.

8. A double-shelled thermotropic reversible color-changing microcapsule, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The application of the double-shell thermochromic microcapsules prepared by the preparation method according to any one of claims 1-7 or the double-shell thermochromic microcapsules according to claim 8 in the production of color-changing inks, temperature-sensitive indicator stickers, anti-counterfeiting coatings, and thermochromic pens.

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