Temperature-sensitive color-changing microcapsule, temperature-sensitive color-changing fabric and preparation method thereof

Abstract

The invention belongs to the technical field of functional textiles, and relates to a temperature-sensitive color-changing microcapsule, a temperature-sensitive color-changing fabric and a preparation method of the temperature-sensitive color-changing microcapsule. The temperature-sensitive color-changing microcapsule comprises an outer shell layer, an inner shell layer and a core layer from inside to outside, the outer shell layer is made of silicon dioxide, the inner shell layer is made of melamine-urea-formaldehyde resin, the core layer is a temperature-sensitive color-changing mixture, and the temperature-sensitive color-changing mixture comprises temperature-sensitive color-changing leuco dye, a color developing agent and a phase change material. The temperature-sensitive color-changing microcapsule is low in temperature-sensitive color-changing response temperature, and the leakage rate of the temperature-sensitive color-changing mixture is low. The temperature-sensitive color-changing microcapsule is fixed on a fabric substrate, so that a temperature-sensitive color-changing fabric can be obtained, and the temperature-sensitive color-changing microcapsule can be widely applied to the technical field of functional textiles.

Description

Technical Field

[0001] The invention belongs to the technical field of functional textiles and relates to a thermosensitive color-changing microcapsule, a thermosensitive color-changing fabric and a preparation method thereof. Background Art

[0002] With the rapid development of smart wearable technology, textiles with both temperature response and active thermal management functions have become a research hotspot. Traditional electrothermal textiles mostly rely on carbon-based materials or metal wires to achieve heating, but their functions are single and they cannot dynamically respond to changes in the environment or human body temperature. Existing thermosensitive color-changing fabrics often use phase change materials combined with hidden dyes to trigger color change through environmental heat sources, which have problems such as slow response speed, high triggering temperature, and poor cycle stability. In recent years, researchers have tried to improve performance through microcapsule modification or conductive network optimization, but have failed to break through the bottleneck of low-voltage drive, fast response and long-term stability. Therefore, there is an urgent need to develop a smart fabric with high-efficiency electrothermal conversion, low color change triggering temperature and strong durability to meet the urgent needs of medical monitoring, military camouflage, personalized wear and other fields for real-time dynamic temperature control and visual feedback.

[0003] CN117816065A discloses a method for preparing and applying thermochromic microcapsules with high color change sensitivity. These microcapsules are suitable for improving the thermal conductivity of microcapsules and reducing the impact of the microcapsule wall material on the heat conduction rate between the core material and the environment. The microcapsule can be applied to silk fabrics. However, the synergistic conductive network does not act directly on the fabric substrate, but rather conducts heat through the microcapsule wall material, which is an indirect path. CN111607972A discloses a thermochromic microcapsule for use on fabrics and its preparation method. These microcapsules utilize the piezoelectric and thermoelectric effects of tourmaline materials, while also utilizing thermally conductive materials to increase the sensitivity of the microcapsules to temperature changes and shorten the color change reaction time. However, the phase change material tetradecyl alcohol only accounts for 30% of the core material, resulting in insufficient thermal buffering capacity. Furthermore, due to its small molecular weight, tetradecyl alcohol is prone to leakage during long-term circulation.

[0004] Therefore, it is necessary to provide a thermochromic microcapsule and a thermochromic material with fast technical response speed, good stability, the ability to meet the rapid response requirements of low-voltage drive and low leakage rate. Summary of the Invention

[0005] The purpose of the present invention is to at least partially solve the above technical problems and provide a thermosensitive color-changing microcapsule, a thermosensitive color-changing fabric and a preparation method thereof.

[0006] The first aspect of the present invention provides a thermochromic microcapsule, which includes an outer shell layer, an inner shell layer and a core layer from the inside to the outside. The material of the outer shell layer is silica, the material of the inner shell layer is melamine-urea-formaldehyde resin, and the core layer is a thermochromic mixture. The thermochromic mixture includes a thermochromic leuco dye, a color developer and a phase change material.

[0007] In some embodiments of the present invention, in the thermosensitive color-changing microcapsules, the shell layer thickness is 50 to 100 nm.

[0008] In some embodiments of the present invention, the thermochromic leuco dye is one or a combination of crystal violet lactone, 6'-(diethylamino)-1',3'-dimethylfluoran and 2'-(dibenzylamino)-6'-(diethylamino)fluoran.

[0009] In some embodiments of the present invention, the temperature-sensitive color-changing mixture includes a temperature-sensitive color-changing leuco dye, diphenol propane (bisphenol A) and a straight-chain saturated fatty alcohol.

[0010] In some embodiments of the present invention, the phase change material is a straight-chain saturated fatty alcohol, preferably hexadecanol or stearyl alcohol.

[0011] In some embodiments of the present invention, in the thermochromic mixture, the mass ratio of the thermochromic leuco dye, the developer and the phase change material is 1:3:(40-70).

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned thermochromic microcapsules, characterized in that the preparation method comprises the following steps:

[0013] S1. The thermochromic mixture is emulsified and then added to a melamine-urea-formaldehyde prepolymer solution to react to form a melamine-urea-formaldehyde resin shell layer that wraps the thermochromic mixture to obtain a single-shell microcapsule;

[0014] S2. The single-shell microcapsules are dispersed in an ethanol-water mixture, and after adding tetraethyl orthosilicate, the pH is adjusted to 9-10 for reaction to form an outer shell layer on the surface of the single-shell microcapsules to obtain the thermosensitive color-changing microcapsules.

[0015] In some embodiments of the present invention, the preparation method of the melamine-urea-formaldehyde prepolymer solution (MUF prepolymer solution) is as follows: urea and melamine are added to a formaldehyde aqueous solution, the temperature is raised to 60-90° C., and stirred in a water bath. After the solution is completely clarified, the reaction is continued for 10-60 minutes to obtain the melamine-urea-formaldehyde prepolymer solution.

[0016] In some embodiments of the present invention, the pH of the formaldehyde aqueous solution is preferably 8.5-9, and the concentration is 3-7%; the mass ratio of urea, melamine and the formaldehyde aqueous solution is 1:1:(40-100).

[0017] In some embodiments of the present invention, in step S1 of the method for preparing the thermochromic microcapsules, the mass ratio of the thermochromic mixture to the melamine-urea-formaldehyde prepolymer is (1-4):1, and the mass of the melamine-urea-formaldehyde prepolymer is the total mass of melamine, urea and formaldehyde in the melamine-urea-formaldehyde prepolymer solution.

[0018] In some embodiments of the present invention, in step S2 of the method for preparing the thermosensitive color-changing microcapsules, the mass ratio of the single-shell microcapsules to tetraethyl orthosilicate is (0.2-10):1.

[0019] In some embodiments of the present invention, in step S2 of the method for preparing the thermosensitive color-changing microcapsules, the volume ratio of ethanol to water in the ethanol-water mixture is (1-5): 1. This volume ratio is key to the size of the silica particles.

[0020] A third aspect of the present invention provides a temperature-sensitive color-changing fabric, comprising:

[0021] fabric base layer;

[0022] Thermochromic layer, the thermochromic layer is fixed to at least one side surface of the fabric base layer, and the material of the thermochromic layer is the above-mentioned thermochromic microcapsule.

[0023] In some embodiments of the present invention, the fabric base layer is a conductive layer, and the conductive layer is used to provide electrical and thermal regulation for the thermosensitive color-changing microcapsules to change color.

[0024] A fourth aspect of the present invention provides a method for preparing the above-mentioned temperature-sensitive color-changing fabric, comprising the following steps:

[0025] (1) preparing a conductive layer;

[0026] (2) preparing the above-mentioned thermosensitive color-changing microcapsules;

[0027] (3) The thermosensitive color-changing microcapsules are mixed with a polyether thickener and a polyester adhesive to prepare a printing paste, and the printing paste is applied to the surface of the conductive layer by screen printing, pre-baked, and cured to obtain the thermosensitive color-changing fabric.

[0028] In some embodiments of the present invention, step (1) specifically comprises: subjecting cotton fabric to graphene oxide (GO) treatment, carboxylation modification, plasma treatment, chemical silver plating and reduction treatment in sequence to obtain the conductive layer, wherein the conductive layer has a composite conductive network formed by nanosilver particles and reduced graphene oxide.

[0029] In some embodiments of the present invention, step (1) of the method for preparing the thermosensitive color-changing fabric is specifically as follows:

[0030] a. Immerse cotton fabric in GO dispersion to obtain GO / cotton.

[0031] b. GO / cotton was carboxylated using a finishing solution containing BTCA (1,2,3,4-butanetetracarboxylic acid), SHP (sodium hypophosphite), and DMSO (dimethyl sulfoxide). BTCA / GO / cotton was obtained after two dips and two rolls, pre-baking at 80-100°C for 3-5 minutes, and curing at 120-160°C for 1-3 minutes.

[0032] Preferably, in the finishing liquid, the content of BTCA (1,2,3,4-butanetetracarboxylic acid) is 100-120 g / L, the content of SHP (sodium hypophosphite) is 80-100 g / L, and the content of DMSO (dimethyl sulfoxide) is 3-6 wt %.

[0033] c. Plasma treatment of BTCA / GO / Cotton;

[0034] Preferably, the helium flow rate of the plasma treatment is 20-25 L / min, the electrode spacing is 3.0-4.0 mm, the treatment power is preferably 190-210 W, and the treatment time is preferably 115-125 s.

[0035] d. The plasma-treated fabric was immersed in a silver ammonia solution, glyoxal was added dropwise, and chemical silver plating was performed for a reaction time of 30 to 90 min to obtain Ag / BTCA / GO / Cotton.

[0036] Preferably, the silver ammonia solution is prepared by taking silver nitrate and adjusting the pH value to 9 to 10 with ammonia water. The ratio of the nitrate to glyoxal is 50 mL:8.75 mmol.

[0037] Preferably, the concentration of the silver ammonia solution is 0.1 to 0.3 mol / L, and the amount of glyoxal added is 5 to 7 mmol.

[0038] Preferably, the plasma-treated fabric is immersed in the silver ammonia solution at a bath ratio of (50-100):1.

[0039] e. Ag / BTCA / GO / Cotton was reduced with 3-10 wt% hydrazine hydrate solution at a temperature of 60-90°C for 1-3 h to obtain Ag / BTCA / rGO / Cotton.

[0040] In some embodiments of the present invention, in step (3) of the above-mentioned method for preparing the thermosensitive color-changing fabric, the mass ratio of the thermosensitive color-changing microcapsules, the polyether thickener, and the polyester adhesive in the printing paste is (8-10): (1-4): (10-15).

[0041] In some embodiments of the present invention, in step (3) of the above-mentioned method for preparing the thermosensitive color-changing fabric, the pre-baking is: pre-baking at 60-80° C. for 5-10 minutes.

[0042] In some embodiments of the present invention, in step (3) of the method for preparing the thermosensitive color-changing fabric, the curing is performed at 110-140° C. for 1-5 minutes.

[0043] Compared with the prior art, the present invention has the following technical effects:

[0044] (1) The present invention develops thermochromic double-layer microcapsules with low response temperature, low leakage rate, and good thermal cycling stability by coating a phase change material system containing a thermochromic leuco dye with a melamine-urea-formaldehyde resin as an inner layer and then coating it with silica as an outer layer. This solves the problem of high color change response temperature and poor thermal cycling stability in the prior art. Experiments have shown that the response temperature of the thermochromic double capsules provided by the present invention is only 50-60°C, and the core material leakage rate is only about 0.02% after 25 thermal cycles.

[0045] (2) The present invention constructs a fabric substrate layer with a graphene / nanosilver synergistic conductive network. After plasma treatment of the fabric, the porosity of the silver layer is reduced, the conductivity is improved, and the energy efficiency is significantly improved compared to similar products. The graphene / nanosilver substrate has a high heating temperature, and the double-shell microcapsule triggering temperature is low, achieving a fast response and good durability. Experiments have shown that when the applied voltage is only 2.5V, the temperature-sensitive color-changing fabric provided by the present invention reaches a high temperature of 180°C within 10 seconds, giving the fabric the triple advantages of efficient heating, rapid response, and long-term stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of the preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0047] Figure 1 The color change of the double-shell microcapsule SiO2-Red-1 prepared in Example 5 at different temperatures is shown;

[0048] Figure 2 A bar chart showing the cycle stability test results of the double-shell microcapsules SiO2-Red-1 prepared in Example 5;

[0049] Figure 3 The 10s heating temperature curve of the Ag / BTCA / rGO / Cotton conductive layer prepared in Example 1 at different voltages is shown;

[0050] Figure 4 The digital image and corresponding infrared image of the double-shell microcapsule SiO2-Red-1 prepared in Example 5 changing color within 0 to 10 seconds on the temperature-sensitive color-changing fabric are shown. DETAILED DESCRIPTION

[0051] The technical solution of the present invention will be further described in detail below through examples and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as limiting the present invention.

[0052] It should be noted that the terms used in this application are generally terms commonly used by those skilled in the art. If there is any inconsistency with commonly used terms, the terms in this application shall prevail.

[0053] Example 1: Preparation of Ag / BTCA / rGO / Cotton conductive layer.

[0054] (1) Cotton fabric was subjected to seven dip-drying cycles of graphene oxide (GO) dispersion to prepare GO / cotton.

[0055] (2) Add BTCA, SHP and DMSO into water to prepare the finishing solution.

[0056] In the finishing solution, the concentration of BTCA was 120 g / L, the concentration of SHP was 100 g / L, and the concentration of DMSO was 6 wt %.

[0057] (3) GO / Cotton was immersed in the finishing liquid (bath ratio 50:1), and after two immersions and two rollings, it was pre-baked at 80°C for 5 minutes and cured at 130°C for 3 minutes to obtain BTCA / GO / Cotton.

[0058] (4) BTCA / GO / Cotton was plasma treated for 120s and then subjected to chemical silver plating.

[0059] The process parameters of the plasma treatment are: treatment power of 200 W, treatment time of 120 s, helium flow rate of 20 L / min, and electrode spacing of 3.5 mm.

[0060] The electroless silver plating process involves preparing a silver-ammonia solution by adjusting the pH of the solution to 9-10 with ammonia water in 50 mL of silver nitrate. The plasma-treated BTCA / GO / cotton was immersed in the silver-ammonia solution for 30 minutes, followed by the addition of 8.75 mmol of glyoxal. The solution was then allowed to stand for 2 hours and then dried at 80°C to obtain the Ag / BTCA / GO / cotton.

[0061] (5) Ag / BTCA / GO / Cotton was reduced with 3 wt% hydrazine hydrate at 90 °C for 1 h to obtain the Ag / BTCA / rGO / Cotton conductive layer.

[0062] Example 2: Preparation of single-shell microcapsules-1

[0063] The masses of the core material (temperature-sensitive color-changing mixture) and the shell material (total mass of urea, melamine, and formaldehyde) are 10 g and 5 g, respectively.

[0064] (1) 0.16 g of 6'-(diethylamino)-1',3'-dimethylfluoran, 0.48 g of bisphenol A and 9.36 g of octadecyl alcohol were stirred and dissolved in a 90°C water bath to prepare a core material ternary oil phase compound (temperature-sensitive color-changing mixture).

[0065] (2) Take an appropriate amount of emulsifier styrene maleic anhydride copolymer and dissolve it in deionized water to prepare a 2 wt% emulsifier solution.

[0066] (3) The core material ternary oil phase compound prepared above was dropped into the emulsifier solution, and emulsified at 50°C with a high-speed shearing machine at a speed of 13,000 rpm / min for 20 minutes to prepare a uniform emulsion.

[0067] (4) Prepare a 5% formaldehyde aqueous solution and adjust the pH to 8.5-9 with triethanolamine. Add urea and melamine (1.2 g, 1.2 g, and 52 g, respectively). Heat to 70°C. After the solution is completely clarified, continue the reaction for 30 min to obtain a MUF prepolymer solution.

[0068] (5) The pH of the emulsion was adjusted to 5-6 with 10 wt% citric acid, and the MUF prepolymer solution was slowly added dropwise thereto. The reaction was pre-reacted at 75°C for 1 h. The temperature was then raised to 85°C while stirring, and the pH was adjusted to approximately 4 with citric acid. The temperature was maintained at 85°C for 2 h, and the pH was adjusted to neutral with sodium hydroxide to terminate the reaction. The mixture was cooled to room temperature, filtered, washed with deionized water several times, and dried. The resulting powder was single-shell microcapsule-1.

[0069] Example 3: Preparation of single-shell microcapsules-2

[0070] The mass of the core material (thermochromic mixture) in step (1) of Example 2 was changed to 10 g and the mass of the shell material (total mass of urea, melamine, and formaldehyde) was 2.5 g. The remaining steps were the same as in Example 2 to obtain single-shell microcapsule-2.

[0071] Example 4: Preparation of single-shell microcapsules-3

[0072] The mass of the core material (thermochromic mixture) in step (1) of Example 2 was changed to 10 g and the mass of the shell material (total mass of urea, melamine, and formaldehyde) were 10 g and 10 g, respectively. The remaining steps were the same as in Example 2 to obtain single-shell microcapsule-3.

[0073] Example 5: Preparation of double-shell microcapsules SiO2-Red-1

[0074] Single-shell microcapsules-1 were dispersed in a mixture of ethanol and water at a ratio of 3:1. The pH of the mixture was adjusted to 9-10 with aqueous ammonia. Tetraethyl orthosilicate (TES) was slowly added dropwise (5g single-shell microcapsules and 1g TES). The mixture was reacted at 40°C for 12 hours. After centrifugal drying, the resulting double-shell microcapsules were designated SiO2-Red-1.

[0075] Example 6: Preparation of double-shell microcapsules SiO2-Red-2

[0076] The single-shell microcapsule-1 in Example 5 was replaced with the single-shell microcapsule-2, and the other steps remained unchanged to obtain the double-shell microcapsule SiO2-Red-2.

[0077] Example 7: Preparation of double-shell microcapsules SiO2-Red-3

[0078] The single-shell microcapsule-1 in Example 5 was replaced with the single-shell microcapsule-3, and the other steps remained unchanged to obtain the double-shell microcapsule SiO2-Red-3.

[0079] Example 8: Preparation of double-shell microcapsules SiO2-Red-1-1

[0080] The ratio of ethanol to water in the ethanol-water mixture in Example 5 was adjusted to 5:1, and the remaining steps remained unchanged to obtain double-shell microcapsules SiO2-Red-1-1.

[0081] Example 9: Preparation of double-shell microcapsules SiO2-Red-1-2

[0082] The ratio of ethanol to water in the ethanol-water mixture in Example 5 was adjusted to 1:1, and the remaining steps remained unchanged to obtain double-shell microcapsules SiO2-Red-1-2.

[0083] Example 10: Preparation of double-shell microcapsules SiO2-Red-1-3

[0084] The masses of the single-shell microcapsules and tetraethyl orthosilicate in Example 5 were adjusted to 5 g and 0.5 g, respectively, and the remaining steps remained unchanged to obtain double-shell microcapsules SiO2-Red-1-3.

[0085] Example 11: Preparation of double-shell microcapsules SiO2-Red-1-4

[0086] The masses of the single-shell microcapsules and tetraethyl orthosilicate in Example 5 were adjusted to 5 g and 25 g respectively, and the remaining steps remained unchanged to obtain double-shell microcapsules SiO2-Red-1-4.

[0087] Comparative Example 1

[0088] GO / cotton was prepared by subjecting cotton fabric to seven dip-drying cycles with a GO dispersion. Then, rGO / cotton was reduced with 3% hydrazine hydrate at 90°C for 1 hour, resulting in the electrothermal substrate. The remaining steps remained unchanged.

[0089] Comparative Example 2

[0090] The single-shell microcapsule 1' was obtained by replacing octadecyl alcohol with hexadecanol and keeping the other steps unchanged.

[0091] The single-shell microcapsule-1 in Example 5 was replaced with single-shell microcapsule-1', and the other steps remained unchanged to obtain double-shell microcapsule SiO2-Red-4.

[0092] Comparative Example 3

[0093] The ratio of ethanol to water in the ethanol-water mixture in Example 5 was adjusted to 1:5, and the other steps remained unchanged. It was found that double-shell microcapsules could not be formed.

[0094] Test Example 1: Color change response temperature test

[0095] Test method: Place the double-shell microcapsules SiO2-Red-1 in Example 5 on a heating platform, adjust the temperature of the heating platform to 20-80°C, and record the color changes of the microcapsules at different temperatures. The results are as follows: Figure 1 shown.

[0096] Depend on Figure 1 It can be seen that the double-shell microcapsules provided in the embodiment of the present invention have a relatively low color change response temperature and can completely change color below 70°C.

[0097] Test Example 2: Color change response time test

[0098] A printing paste was prepared, wherein the printing paste formulation comprises 1 wt% polyether thickener, 10 wt% polyester binder, 8 wt% microcapsules, and the remainder being deionized water. The Ag / BTCA / rGO / Cotton conductive layer prepared in Example 1 was screen-printed at 45° using a squeegee, pre-baked at 80°C for 5 minutes, and fixed at 140°C for 3 minutes. The resulting fabric is a temperature-sensitive color-changing fabric. The microcapsules can be the single-shell microcapsules prepared in Examples 2-4, the double-shell microcapsules prepared in Examples 5-11, or the double-shell microcapsules prepared in Comparative Example 2.

[0099] A driving voltage of 2.50 V was applied to the prepared thermosensitive color-changing fabric, and the time taken for the microcapsules on the thermosensitive color-changing fabric to completely change color was measured with a stopwatch, which was recorded as the response time. The results are shown in Table 1.

[0100] Test Example 3: Microcapsule Leakage Rate Test

[0101] Test method: Weigh microcapsules and place them in a watch glass. Heat at 70°C for 20 minutes, then hold at 20°C for 20 minutes. Repeat this cycle 25 times. Record the mass each time and calculate the final leakage rate using the following formula.

[0102] Leakage rate = m1-m n / m1×100% where m1 is the initial mass, m n is the mass after n heating-cooling cycles.

[0103] The double-shell microcapsules SiO2-Red-1 prepared in Example 5 were subjected to a cycle stability test. The cycle stability test results are shown in the bar graph. Figure 2 As shown. Figure 2 It can be seen that after 25 thermal cycles, the leakage rate is only 0.02%, indicating that the prepared microcapsules have good thermal stability and reusability.

[0104] Test Example 4: Microcapsule Dispersibility Test

[0105] Test method: Weigh the microcapsules and disperse them in water. Stir evenly and place them for 7 days to observe whether there is any precipitation to test the dispersibility of the microcapsules.

[0106] The color change response time, leakage rate after 25 thermal cycles, and dispersibility of the microcapsules prepared in Examples 2-11 of the present invention and Comparative Example 2 are shown in Table 1.

[0107] Table 1 Microcapsule response time, leakage rate and dispersion test results

[0108]

[0109]

[0110] It can be seen from Examples 2 to 5 that, compared with double-shell microcapsules, the response time of single-shell microcapsules is slightly faster than that of double-shell microcapsules, but the leakage rate of double-shell microcapsules is significantly lower.

[0111] As can be seen from Examples 5, 8, and 9 and Comparative Example 3, when forming double-shell microcapsules, a higher ethanol-to-water ratio results in smaller silica particles, a denser loading on the surface of the single-shell microcapsules, and a lower leakage rate, but the triggering response time of the thermochromic material changes slightly. However, when the water ratio is too high, the hydrolysis reaction of the silicon source is greatly accelerated, resulting in larger silica particles that are easier to handle in a free state rather than being deposited in a targeted manner on the surface of the single-shell microcapsules, which in turn increases the leakage rate.

[0112] As shown in Examples 5, 10, and 11, increasing the ratio of single-shell microcapsules to tetraethyl orthosilicate results in a less dense silica shell on the surface, leading to an increased leakage rate. However, decreasing the ratio (i.e., increasing the amount of tetraethyl orthosilicate) results in an excessive silica loading, resulting in poor dispersibility in the solution.

[0113] It can be seen from Example 1 and Comparative Example 1 that when the substrate is a pure RGO substrate, the electrothermal effect of the pure graphene substrate is poor. After power is applied, the heating temperature of the substrate is too low and cannot reach the temperature at which the microcapsules change color.

[0114] As can be seen from Example 5 and Comparative Example 2, the response time of hexadecanol is slightly faster than that of octadecanol. This is because the temperature-sensitive color change trigger temperature of hexadecanol is lower than that of octadecanol, the hexadecanol molecular chain is shorter, the intermolecular forces (van der Waals forces) are weaker, and the melting point is lower. At the same time, because the hexadecanol molecule is smaller, the leakage rate of Comparative Example 2 also increases.

[0115] Test Example 5: Conductive performance test of fabric base layer

[0116] The surface resistance of the fabric base materials prepared in Comparative Example 1 and Example 1 was tested using a resistivity meter. Five different positions of each fabric were measured, and the average value was taken as its surface resistance value. The results are shown in Table 2.

[0117] A driving voltage of 2.50 V was applied to the fabric base materials prepared in Comparative Example 1 and Example 1, and the surface temperature of the materials was measured at 2 s and 10 s. The results are shown in Table 2.

[0118] As shown in Table 2, the conductive substrate prepared in Example 1 has low resistance and high electrothermal temperature, while the conductive substrate prepared in Comparative Example 1 has poor electrothermal performance. 2 / R)t, it can be seen that the greater the resistance, the smaller the thermal energy and the lower the heating temperature.

[0119] Table 2 Conductive properties and quick response test results of fabric base materials

[0120]

[0121] A driving voltage of 0.50 to 2.50 V was applied to the fabric base material prepared in Example 1, and the surface temperature of the material was measured after 10 seconds. The results were as follows: Figure 3 shown.

[0122] Depend on Figure 3 As shown in the figure, the electrothermal temperature of the material when tested at different voltages for 10s indicates that U 2 There is a positive correlation between T.

[0123] Test Example 6

[0124] The temperature-sensitive color-changing fabric prepared by the double-shell microcapsule SiO2-Red-1 prepared in Example 5 was subjected to a driving voltage of 2.50V. The color-changing digital image and the corresponding infrared image results within 0 to 10 seconds were as follows: Figure 4 As shown in the image, the discolored portion is the double-shelled SiO2-Red-1 microcapsule. When power is off, the image appears pink. After just 2 seconds of power application, the color disappears, ultimately revealing a transparent shape on the base fabric. The corresponding infrared digital image shows that at 10 seconds, the maximum temperature measured on the fabric surface exceeds 180°C, demonstrating excellent Joule heating and electrothermochromic properties.

[0125] Although some embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined in the claims and their equivalents.

Claims

1. A thermosensitive color-changing microcapsule, characterized in that: The thermosensitive color-changing microcapsule includes an outer shell layer, an inner shell layer and a core layer from the inside to the outside. The material of the outer shell layer is silicon dioxide, the material of the inner shell layer is melamine-urea-formaldehyde resin, and the core layer is a thermosensitive color-changing mixture. The thermosensitive color-changing mixture includes a thermosensitive color-changing leuco dye, a color developer and a phase change material.

2. The thermosensitive color-changing microcapsule according to claim 1, characterized in that: The thickness of the outer shell layer is 50-100 nm.

3. The thermosensitive color-changing microcapsule according to claim 1, characterized in that: The temperature-sensitive color-changing leuco dye is one or a combination of crystal violet lactone, 6'-(diethylamino)-1',3'-dimethylfluoran and 2'-(dibenzylamino)-6'-(diethylamino)fluoran.

4. The thermosensitive color-changing microcapsule according to claim 1, characterized in that The temperature-sensitive color-changing mixture comprises a temperature-sensitive color-changing leuco dye, diphenol propane and a straight-chain saturated fatty alcohol.

5. The thermosensitive color-changing microcapsule according to claim 1, characterized in that The phase change material is octadecyl alcohol or hexadecanol.

6. The thermosensitive color-changing microcapsule according to claim 1, characterized in that: In the thermochromic mixture, the mass ratio of the thermochromic leuco dye, the developer and the phase change material is 1:3:(40-70).

7. A method for preparing the thermosensitive color-changing microcapsules according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1. The thermochromic mixture is emulsified and then added to a melamine-urea-formaldehyde prepolymer solution to react to form a melamine-urea-formaldehyde resin shell layer that wraps the thermochromic mixture to obtain a single-shell microcapsule; S2. The single-shell microcapsules are dispersed in an ethanol-water mixture, tetraethyl orthosilicate is added, the pH is adjusted to 9-10, and the reaction is carried out to form the outer shell layer on the surface of the single-shell microcapsules to obtain the thermosensitive color-changing microcapsules.

8. The preparation method according to claim 6, characterized in that In step S2, the mass ratio of the single-shell microcapsules to tetraethyl orthosilicate is (0.2-10):

1.

9. The preparation method according to claim 6, characterized in that In step S2, the volume ratio of ethanol to water in the ethanol-water mixture is (1-5):

1.

10. A thermosensitive color-changing fabric, characterized in that: The temperature-sensitive color-changing fabric comprises: fabric base layer; The thermochromic layer is fixed to the surface of at least one side of the fabric base layer, and the material of the thermochromic layer is the thermochromic microcapsule according to any one of claims 1 to 6.

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