Preparation method and application of high-variable-color-sensitivity temperature-sensitive color-changing microcapsules

Abstract

This invention discloses a method for preparing and applying high-sensitivity thermochromic microcapsules, belonging to the field of thermochromic microcapsule preparation technology. This method is suitable for improving the thermal conductivity of microcapsules, reducing the influence of the microcapsule wall material on the thermal conduction rate between the core material and the environment, and is applicable to preparing antibacterial thermochromic silk fabrics with different color-changing temperatures. A three-component core material is encapsulated inside a shell material. While the wall material monomers are polymerized, nano-silver is doped. Under low temperature and low vacuum, ultraviolet-induced secondary polymerization improves the degree of polymerization and crystallinity of polystyrene, reducing defects between the filler and the wall material, resulting in a tighter bond between the two, thus preparing highly thermally conductive and antibacterial thermochromic microcapsules; antibacterial thermochromic silk fabric is then obtained through printing. This invention uses nano-silver to modify the microcapsule wall material and increases the wall material density through ultraviolet irradiation, which not only improves the thermal conductivity of the wall material and the color-changing sensitivity of the thermochromic microcapsules, but also endows the fabric with durable antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of thermosensitive color-changing microcapsule preparation technology, and in particular to a method for preparing and applying a high color-changing sensitivity thermosensitive color-changing microcapsule. Background Technology

[0002] Microcapsules are microscopic, closed systems with a core-shell structure. Microencapsulation technology refers to the technique of encapsulating chemically sensitive, volatile, and difficult-to-store substances—which are unsuitable for direct use—into microscopic capsules using polymers with film-forming properties. A microcapsule consists of two parts: a capsule wall and a core. The polymer with film-forming properties is called the wall material, and the encapsulated active substance is called the core material. The advantages of microencapsulation technology include: protecting the core material, improving its durability, increasing its utilization rate, and being environmentally friendly. Microencapsulation technology is widely used in thermochromic materials. Organic thermochromic materials are the most studied, and among these, the most mature research is on three-component thermochromic materials, composed of a leucocyanide, a developer, and a solvent. At higher temperatures, the solvent undergoes a solid-liquid phase transition, and proton transfer occurs between the leucocyanide and the developer, resulting in color development or change. This ternary thermochromic compound exhibits poor solvent and heat resistance. Its color changes with temperature accompanied by a phase transition, making it susceptible to environmental influences and prone to losing its reversible color-changing ability. Therefore, encapsulating it using microencapsulation technology can improve the stability of the thermochromic material and extend its lifespan.

[0003] The wall material is the substance that encapsulates the core material within the microcapsule and prevents leakage. Wall materials can be inorganic or organic, with polymers being the most commonly used. The performance of the wall material significantly impacts the quality of the microcapsule product. The selection of the wall material must consider many factors, such as: opposite solubility to the core material; excellent toughness, durability, and strength; good sealing properties; a melting point higher than the core material; and good moldability and resistance to adhesion. Polystyrene (PS) is an excellent wall material due to its good chemical properties, high mechanical strength, good film-forming properties, non-toxicity, high transparency, and low cost and availability. Furthermore, polystyrene offers good moldability and prevents microcapsules from sticking together, making it a highly sought-after environmentally friendly material in today's society. However, the presence of the microcapsule wall material weakens the thermal conductivity between the internal phase change material and the external environment, leading to a decrease in the temperature sensitivity of the thermochromic material. Furthermore, polystyrene itself has certain thermal insulation properties, with a thermal conductivity of only 0.08 W / (m·K). Using polystyrene as the wall material in thermochromic microcapsules significantly impacts the temperature-sensitive performance of the thermochromic material. Temperature sensitivity is a crucial factor for thermochromic materials, and rapid color change is one of the desired goals. Modifying the polystyrene wall material to improve the thermal conductivity of the encapsulated microcapsules and enhance the temperature sensitivity of the thermochromic material is of great significance. Improving the microcapsule polymer wall material through doping with high thermal conductivity materials is a common method. However, due to the significant differences in the physical and chemical properties of the matrix and filler, the interface formed between them is weak and prone to defects. Preliminary findings suggest that defects such as interfacial phases and pores exist at the filler-matrix interface, resulting in poor interfacial bonding, requiring improvement through physical or chemical methods.

[0004] Furthermore, silk fabrics, as textile materials, possess characteristics such as softness, smoothness, comfort, and strong adaptability to the human body, making them particularly suitable as clothing materials for technicians engaged in high-intensity work for short periods, such as surgical gowns, as they can reduce physical fatigue and improve comfort. However, silk is essentially a natural protein fiber, which easily traps and breeds a large number of bacteria in humid air. As a clothing material for special applications such as medical surgical gowns, which are easily exposed to bacteria and viruses, it also lacks antibacterial properties. Temperature management for specific personnel is one of the application directions of smart textiles. Combining thermosensitive color-changing dyes with silk fabrics to create thermosensitive color-changing silk fabrics for visual monitoring of the human body surface temperature is currently an important research area. Existing color-changing silk technologies involve conventionally dyeing silk fabrics to give them overall color-changing properties. Because the surface of the color-changing microcapsules is completely covered, the softness of the color-changing silk fabric is reduced, making it difficult to create personalized patterns through localized dyeing. Moreover, the dye utilization rate during the dyeing process is low, increasing the technical and raw material costs of color-changing silk fabrics. Summary of the Invention

[0005] To address the above issues, this invention utilizes the high thermal conductivity of nano-silver (414 W / (m·K)) to improve the thermal conductivity of the microcapsule wall material by doping with polystyrene. Furthermore, the prepared microcapsules undergo secondary UV-initiated polymerization under low temperature and low vacuum conditions. This increases the degree of polymerization, crystallinity, and density of the polymer, thereby enhancing molecular orientation consistency. It also reduces interfacial defects between polystyrene and nano-silver, resulting in a more uniform distribution of nano-silver in the wall material and a tighter bond between the wall material and the filler, further improving the thermal conductivity of the wall material and thus enhancing the color-changing sensitivity of the thermochromic microcapsules upon heating. Finally, the invention leverages the inherent antibacterial properties of nano-silver to simultaneously improve the thermal conductivity and thermochromic sensitivity of the thermochromic microcapsule shell material, imparting lasting antibacterial properties.

[0006] This invention provides a method for preparing high-sensitivity thermosensitive color-changing microcapsules, comprising the following steps:

[0007] (1) Preparation of thermosensitive color-changing microcapsule precursor emulsion: Bisphenol A dye was dissolved in octadecanol and mixed evenly as core material. Then styrene was added to the core material, followed by water and sodium dodecylbenzenesulfonate. Azobisisobutyronitrile was added as an initiator to initiate styrene polymerization. The emulsion was obtained by ultrasonic emulsification.

[0008] (2) Preparation of wall material modified high thermal conductivity thermosensitive color-changing microcapsules: The emulsion is heated to 70-75℃ and kept at the temperature for 20-30 min. Then, nano silver emulsion is added dropwise. While styrene polymerizes to form wall material, it is doped. The reaction continues for 5-6 h. After centrifugation, washing and drying, nano silver doped polystyrene high thermal conductivity thermosensitive color-changing microcapsules are obtained.

[0009] (3) Photo-initiated secondary polymerization treatment of thermosensitive color-changing microcapsules: The thermosensitive color-changing microcapsules obtained in step (2), polyvinylpyrrolidone, and α-hydroxyalkyl phenyl ketone were added to water and mixed and stirred. Then, the mixture was subjected to secondary polymerization under ultraviolet light at low temperature and low vacuum. After centrifugation, washing, and drying, high color-changing sensitivity thermosensitive color-changing microcapsules were obtained.

[0010] Furthermore, in step (1), the mass ratio of bisphenol A dye to octadecyl alcohol is 1:16-20.

[0011] Furthermore, in step (1), the mass ratio of styrene to core material is 12:3 to 5.

[0012] Furthermore, in step (1), the mass ratio of styrene to water is 12:150-170.

[0013] Furthermore, in step (1), the mass ratio of styrene to sodium dodecylbenzenesulfonate is 12:1.5 to 2.

[0014] Furthermore, in step (1), the mass ratio of styrene to azobisisobutyronitrile initiator is 12:2-3.

[0015] Furthermore, in step (2), the concentration of nano-silver in the nano-silver emulsion is 0.5–1 mol / L.

[0016] Furthermore, the particle size of the nano-silver is 1–100 nm.

[0017] Furthermore, in step (2), the mass ratio of styrene to nano-silver emulsion is 12:5 to 30.

[0018] Preferably, the mass ratio of styrene to nano-silver emulsion is 12:20.

[0019] Furthermore, in step (3), the mass ratio of thermosensitive color-changing microcapsules to polyvinylpyrrolidone is 20:1 to 3.

[0020] Furthermore, in step (3), the mass ratio of thermosensitive color-changing microcapsules to α-hydroxyalkyl phenyl ketone is 20:1 to 5.

[0021] Furthermore, the low temperature mentioned in step (3) is 0 to 15°C.

[0022] Furthermore, the low vacuum mentioned in step (3) is 0.1 to 0.3 MPa.

[0023] Furthermore, the parameters of the ultraviolet irradiation mentioned in step (3) are 12-15W and 365nm.

[0024] Furthermore, the duration of the secondary polymerization in step (3) is 2 to 10 hours.

[0025] Preferably, the duration of the secondary polymerization is 8 hours.

[0026] This invention provides high color-changing sensitivity thermosensitive color-changing microcapsules prepared according to the above method.

[0027] The high color-changing sensitivity thermosensitive color-changing microcapsules provided by this invention have applications in the textile and dyeing fields.

[0028] This invention provides a method for preparing an antibacterial, thermosensitive, color-changing printed silk fabric, comprising the following steps:

[0029] The thermosensitive color-changing microcapsules, thickener, adhesive and water prepared above are mixed and stirred evenly to prepare printing paste. The paste is then used to print, pre-dry, bake, soap and wash and dry silk fabrics to prepare antibacterial thermosensitive color-changing printed silk fabrics.

[0030] Furthermore, the thickener is one of the following: natural organic polymer thickener, polyacrylic acid thickener, and polyurethane thickener.

[0031] Furthermore, the adhesive is one of polyacrylate copolymer adhesives, butadiene emulsion copolymers, vinyl acetate copolymer adhesives, and polyurethane adhesives.

[0032] Furthermore, the mass percentage of thermosensitive color-changing microcapsules in the printing paste is 4-6%.

[0033] Furthermore, the thickener in the printing paste accounts for 2-3% of the total mass.

[0034] Furthermore, the binder accounts for 5-10% of the mass of the printing paste.

[0035] Preferably, the binder content in the printing paste is 10% by mass.

[0036] Furthermore, the printing method is either flatbed printing or rotary screen printing.

[0037] Furthermore, the pre-baking temperature is 60-110℃, and the pre-baking time is 30-300s.

[0038] Furthermore, the baking temperature is 110-130℃, and the baking time is 30-120s.

[0039] Furthermore, the concentration of soap flakes in the soap washing process is 2-5 g / L, the soap washing temperature is 25-45℃, and the soap washing time is 10-30 min.

[0040] The present invention provides an antibacterial thermosensitive color-changing printed silk fabric prepared by the above method.

[0041] The present invention also provides the application of antibacterial thermosensitive color-changing silk fabric prepared by the above preparation method, including the following steps: the thermosensitive color-changing silk fabric prepared by using different phase change materials has different color-changing temperatures; the thermosensitive microcapsule dye with tetradecanol as solvent has a color-changing temperature near human body temperature and can be used for human body temperature environment indication.

[0042] Furthermore, in order to achieve the effect of different patterns appearing at different temperatures on color-changing silk fabrics, temperature-sensitive microcapsule dyes with different color-changing temperatures can be printed on the same side of the fabric. After the temperature is increased, the patterns will appear or disappear one by one.

[0043] Furthermore, antibacterial thermosensitive color-changing silk fabrics can be applied to clothing that requires human body temperature management and antibacterial properties, such as medical work clothes. They can indicate the temperature of the external environment of the human body and effectively kill contaminated bacteria.

[0044] Beneficial effects:

[0045] 1. This invention uses nano-silver to dope polystyrene wall materials. Polystyrene has good film-forming properties and microcapsule shell molding properties, but it also has a certain thermal insulation effect, which reduces the thermal conductivity between the environment and the core material. Nano-silver has high thermal conductivity. Doping it into polystyrene improves the thermal conductivity of the microcapsule wall material. Secondary polymerization further increases the thermal conductivity from 0.0495 W / (m·K) before modification to 0.1466 W / (m·K) after modification, a 196.2% increase, thereby improving the color-changing sensitivity of the microcapsules when heated. Furthermore, nano-silver has a strong killing effect on dozens of pathogenic microorganisms without inducing drug resistance. The addition of nano-silver endows the temperature-sensitive color-changing microcapsules with long-lasting antibacterial properties.

[0046] 2. This invention uses printing technology to apply antibacterial, high thermal conductivity, temperature-sensitive color-changing microcapsules to silk fabrics. The process is simple and avoids the problems of long dyeing time and low dye uptake rate in the dyeing process of silk fabrics using temperature-sensitive color-changing dyes.

[0047] 3. This invention uses printing technology to apply antibacterial, high thermal conductivity, temperature-sensitive color-changing microcapsules to silk fabrics, which can effectively improve the problem of a significant decrease in the overall hand feel of the fabric caused by dyeing. Furthermore, the prepared temperature-sensitive color-changing printed fabric not only has high color-changing sensitivity but also has long-lasting antibacterial properties. Attached Figure Description

[0048] Figure 1 A flowchart illustrating the application of high-sensitivity thermochromic microcapsules.

[0049] Figure 2 The images shown are microscopic images of the thermosensitive color-changing silk fabric obtained by printing in Example 5 at low and high magnification, where Figure a is a low-magnification microscopic image and Figure b is a high-magnification microscopic image. Detailed Implementation

[0050] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0051] The preparation process of the nano-silver emulsion in the following examples or comparative examples is as follows: nano-silver particles are prepared using silver nitrate as the silver source, hydrazine hydrate as the reducing agent, and polyol as the surfactant. A certain amount of the prepared nano-silver powder and dispersant are dissolved in deionized water and stirred evenly to obtain the nano-silver emulsion.

[0052] Example 1

[0053] This embodiment describes the synthesis of melamine-formaldehyde resin thermosensitive color-changing microcapsules.

[0054] Crystal violet lactone, bisphenol A, and tetradecyl alcohol were mixed in a mass ratio of 1:4:70 and heated and stirred at 70°C for 2 hours, followed by cooling to obtain a three-component thermosensitive color-changing core material. 2g of melamine, 3.86g of formaldehyde solution, and 22mL of distilled water were placed in a three-necked flask and placed in a 70°C water bath. The pH of the solution was adjusted to 9.0 using triethanolamine, and after stirring for 1 hour, a transparent prepolymer solution was obtained.

[0055] Add 3g of styrene-maleic anhydride copolymer emulsifier to 100g of deionized water, and add 3g of the three-component thermosensitive color-changing core material. Emulsify and stir in a 60℃ water bath for 15min to form a white emulsion. Place the emulsion in a three-necked flask, and add the previously prepared transparent prepolymer solution dropwise. Then, adjust the pH of the system to 4.0 using a 10% wt citric acid solution. After 30min of polymerization, gradually add 10mL of 1mol / L nano silver emulsion, and stir for 2.5h. The reaction temperature is controlled at 75℃. After the reaction is complete, adjust the pH of the system to 7.0 using a 20% sodium hydroxide solution. Then cool, filter, wash, and dry to obtain the melamine-formaldehyde resin thermosensitive color-changing microcapsule dye.

[0056] The results showed that microcapsules made with urea-formaldehyde resin as the wall material were not smooth spheres and were severely adhered to each other, indicating that the method of preparing microcapsules was not very effective.

[0057] Example 2

[0058] This embodiment describes the synthesis of nano-silver-doped polystyrene thermosensitive color-changing microcapsules.

[0059] Preparation of thermosensitive color-changing microcapsules by emulsion polymerization: 0.94 g of bisphenol A dye was dissolved in 18.75 g of octadecyl alcohol and sonicated until homogeneous, serving as the core material. 4 g of the prepared core material was placed in a beaker, 12 g of styrene was added, and after sonication, 160 g of deionized water was added, followed by 1.76 g of sodium dodecylbenzenesulfonate and 2.64 g of azobisisobutyronitrile initiator. The mixture was then sonicated to emulsify, yielding an emulsion. The emulsion was then transferred to a flask and heated to 75 °C and maintained at this temperature. 30 min after polymerization began, 1 mol / L nano-silver emulsion was added dropwise under stirring. The mass ratio of styrene to nano-silver emulsion was 12:20, and the reaction continued for 6 h. Afterward, the mixture was centrifuged, washed, and dried to obtain nano-silver-doped polystyrene thermosensitive color-changing microcapsules.

[0060] The results showed that polystyrene has good stability and excellent film-forming properties, while the microcapsule dyes doped with nano-silver exhibited rapid thermo-sensitive color change and high sensitivity.

[0061] Example 3

[0062] This embodiment further improves the thermal conductivity of the thermosensitive color-changing microcapsules of Example 2.

[0063] The microcapsules prepared in Example 2, polyvinylpyrrolidone as a stabilizer, and α-hydroxyalkyl phenyl ketone as a photoinitiator were added to water in a ratio of 10:1:1 and ultrasonically dispersed. The mixture was stirred under low temperature (0°C) and low vacuum (0.1 MPa) conditions and irradiated with ultraviolet light (12W, 365nm) for 8 hours to carry out secondary photoinitiated polymerization. After the reaction was completed, the microcapsules were centrifuged, washed, and dried to obtain the highly sensitive thermochromic microcapsules.

[0064] Example 4

[0065] This embodiment describes the preparation of a thermosensitive color-changing printing paste.

[0066] Take 5% of the high color-changing sensitivity thermochromic microcapsules synthesized in Example 3, 3% of the thickener, 5% of the binder, and the remainder is water; mix the thermochromic microcapsules, thickener, binder and water and stir evenly to obtain thermochromic printing paste.

[0067] The results showed that the components of the color paste were uniformly mixed, with no impurities, large particles, or lumps.

[0068] Example 5

[0069] This embodiment describes the preparation of thermosensitive color-changing printed silk fabric.

[0070] The printing paste prepared in Example 4 was printed onto one side of the silk fabric using screen printing. The printing was done twice, pre-baked at 60°C for 180s, baked at 110°C for 60s, with a soap flake concentration of 5g / L, soaped at 40°C for 20min, and dried to obtain the thermosensitive color-changing silk fabric.

[0071] The results showed that the thermosensitive dye was evenly distributed on the silk fabric, and the fabric color change was obvious and sensitive with high contrast.

[0072] Figure 2 The low-magnification and high-magnification micrographs of the printed silk fabric show that the dye is evenly distributed on the surface and inside the fabric.

[0073] Comparative Example 1

[0074] This comparative example describes the preparation of polystyrene thermochromic microcapsules without nano-silver doping.

[0075] Unlike Example 2, the polymerization stage after ultrasonic emulsification does not involve the addition of nano-silver emulsion.

[0076] The results showed that, due to the thermal insulation properties of polystyrene, the thermosensitive color-changing microcapsules prepared in this case exhibited lower color-changing sensitivity and a slower color-changing speed after heating compared to Example 2. However, the high thermal conductivity of nano-silver demonstrated that the addition of nano-silver could improve the color-changing sensitivity of the microcapsule dye.

[0077] Comparative Example 2

[0078] This comparative example demonstrates the preparation of thermosensitive color-changing microcapsules with different amounts of silver nanoparticles in polystyrene wall materials.

[0079] Unlike Example 2, the mass ratio of styrene to nano-silver emulsion used was 12:5, 12:10, 12:15, 12:25 and 12:30, respectively.

[0080] Comparative Example 3

[0081] This comparative example involves subjecting thermosensitive color-changing microcapsules to ultraviolet light irradiation for different durations.

[0082] Unlike Example 2, the ultraviolet light exposure time was 2h, 4h, 6h, and 10h.

[0083] Comparative Example 4

[0084] This comparative example demonstrates the preparation of thermosensitive color-changing printing pastes with different amounts of adhesive.

[0085] Unlike Example 3, the amount of adhesive used was 8%, 10%, 12%, and 15%, respectively.

[0086] Thermal conductivity test

[0087] 1. Comparison of thermal conductivity of thermosensitive color-changing microcapsules with different amounts of silver nanoparticles in polystyrene wall materials

[0088] The thermal conductivity of thermosensitive color-changing microcapsules prepared with different amounts of nano-silver emulsions in Examples 2, 1, and 2 was tested using a thermal conductivity analyzer.

[0089] Table 1 shows the effect of different amounts of nano-silver emulsion on the thermal conductivity of thermochromic microcapsules.

[0090]

[0091]

[0092] Table 1 shows the effect of different amounts of nano-silver emulsion on the thermal conductivity of thermosensitive color-changing microcapsules. As the amount of nano-silver emulsion increases, the thermal conductivity initially increases slowly, then rapidly, and finally increases slowly again. When the mass ratio of styrene to nano-silver emulsion is 12:5 and 12:10, the amount of nano-silver particles doped in the polystyrene is relatively small, and the thermal conductivity of the microcapsules does not increase significantly. When the mass ratio increases to 12:15, the thermal conductivity increases from 0.0495 W / (m·K) without added nano-silver to 0.0921 W / (m·K), an increase of 86.0%. With the increase of nano-silver emulsion, the number of successfully doped nano-silver particles increases, resulting in a significant increase in thermal conductivity. When the mass ratio increases to 12:20, the thermal conductivity increases by 180.6%. At this point, the amount of nano-silver doped in the polystyrene wall material increases, and the nano-silver loading is relatively uniform, or a small number of thermally conductive pathways are formed on the polystyrene wall material, resulting in a significant improvement in thermal conductivity. Subsequently, the improvement in thermal conductivity was not significant with the increase in the amount of nano-silver emulsion, limiting the successful loading of nano-silver particles onto polystyrene wall materials. The effect of increasing nano-silver emulsion dosage on the color of the thermochromic material itself also gradually became apparent. To reduce this effect and considering the principle of material conservation, a styrene to nano-silver emulsion mass ratio of 12:20 was selected as the optimal dosage.

[0093] 2. Compare the thermal conductivity of microcapsules after treatment with different UV light exposure durations.

[0094] The thermal conductivity of the microcapsules treated with ultraviolet light for different durations in Examples 2, 3, and Comparative Example 3 was tested using a thermal conductivity analyzer, and the improvement in thermal conductivity compared to microcapsules without nano-silver doping and ultraviolet light-induced secondary polymerization was calculated.

[0095] Table 2 shows the effect of different photo-initiated secondary polymerization durations on the thermal conductivity of thermochromic microcapsules.

[0096]

[0097] As shown in Table 2, the thermal conductivity of the thermochromic microcapsules initially increased and then decreased with increasing photoinitiation time. With the addition of the photoinitiator and the application of 365nm ultraviolet light, the photoinitiator initiated the secondary polymerization of polystyrene. Polymerization under low temperature and low vacuum conditions caused shrinkage of the macromolecular chain segments. With increasing irradiation time, the degree of polymerization and crystallinity of polystyrene increased, the consistency of molecular orientation gradually improved, and the intermolecular porosity decreased, leading to an increase in the density of the microcapsule wall material. Furthermore, the surface defects between polystyrene and nano-silver decreased, resulting in a more compact structure and improved thermal conductivity. The secondary photoinitiated polymerization of polystyrene reached saturation at 8 hours of irradiation. When the irradiation time was 10 hours, its thermal conductivity decreased because the degree of polymerization of polystyrene had reached its maximum. Continued application of ultraviolet light caused the macromolecular chain segments of polystyrene to decay or degrade to some extent, resulting in a slight decrease in its thermal conductivity. Therefore, 8 hours was selected as the optimal time for ultraviolet photoinitiated secondary polymerization, increasing the thermal conductivity by 196.2%.

[0098] Fastness test

[0099] Comparison of the color fastness of printed fabrics to dry and wet rubbing and washing with different amounts of adhesive

[0100] The printing pastes prepared in Example 4 and Comparative Example 4 were used to print on silk fabrics using the method in Example 4. The fastness to dry and wet rubbing and the fastness to washing were tested, and then the results were rated by comparing the gray scale under a D65 light source in a Judge QC standard light source box.

[0101] Table 3 shows the dry and wet rubbing fastness and washing fastness of printed fabrics with different adhesive dosages.

[0102]

[0103] Table 3 shows the dry and wet rubbing fastness and washing fastness of printed fabrics with different adhesive dosages. As the amount of adhesive increases, the fastness shows a trend of first increasing and then stabilizing. Considering the green environmental protection and the fact that the increase in adhesive dosage will affect the hand feel of silk fabrics, 10% is selected as the optimal dosage.

[0104] Thermosensitive color change performance test

[0105] Optical properties of antibacterial thermosensitive color-changing printed silk fabric at different temperatures were tested.

[0106] To visually observe the color changes of printed fabrics before and after color change and the recovery, the nano-silver-doped polystyrene thermochromic microcapsule dye prepared in Example 2 was used to prepare a printing paste at 10% of the optimal adhesive amount selected in the fastness test, and the silk fabric was printed according to the printing process in Example 5. The color changes of the thermochromic microcapsule printed fabrics were observed under a D65 light source using a Judge QC standard light source box.

[0107] Table 4 shows the Lab values ​​of thermosensitive color-changing silk fabrics at different temperatures.

[0108]

[0109] Table 4 shows the Lab values ​​of thermosensitive color-changing silk fabrics at different temperatures. The data shows that as the temperature increases, the fabric color gradually becomes lighter, the contrast is obvious, the color change is relatively fast, and the fabric eventually changes from dark blue to nothing.

[0110] Antibacterial performance test

[0111] The untreated silk fabric, the thermosensitive color-changing microcapsules prepared in Example 2 and Comparative Example 1 were used to prepare color pastes, and the printed silk fabrics were subjected to comparative antibacterial tests. The treated and untreated silk fabrics were cut into 4cm×4cm pieces and treated with Escherichia coli and Staphylococcus aureus, respectively.

[0112] Table 5 shows the inhibition rates of different treatments on Escherichia coli and Staphylococcus aureus in silk fabrics.

[0113]

[0114] As shown in Table 5, untreated silk fabric was used as a blank control, with a sterilization rate of 0% for quantitative comparative analysis. The table shows that the thermosensitive color-changing silk fabric prepared with silver-doped thermosensitive color-changing microcapsules in Example 2 achieved an inhibition rate of over 99% against both *Escherichia coli* and *Staphylococcus aureus*. In contrast, the undoped silver-doped fabric in Comparative Example 1 showed almost no inhibitory effect on the two bacteria tested.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application, and all such modifications or substitutions should be covered within the scope of the claims of this application.

Claims

1. A method for preparing a thermosensitive color-changing microcapsule with high color-changing sensitivity, characterized in that, Includes the following steps: (1) Preparation of thermosensitive color-changing microcapsule precursor emulsion: Bisphenol A dye was dissolved in octadecanol and mixed evenly as core material. Then styrene was added to the core material, followed by water and sodium dodecylbenzenesulfonate. Azobisisobutyronitrile was added as an initiator to initiate styrene polymerization. The emulsion was obtained by ultrasonic emulsification. (2) Preparation of wall material modified high thermal conductivity thermosensitive color-changing microcapsules: The emulsion was heated to 70~75 ℃ and kept at the temperature for 20~30 min. Then, nano silver emulsion was added dropwise. While styrene polymerized to form the wall material, it was doped. The reaction continued for 5~6 h. After centrifugation, washing and drying, nano silver doped polystyrene high thermal conductivity thermosensitive color-changing microcapsules were obtained. (3) Photo-initiated secondary polymerization treatment of thermochromic microcapsules: The thermochromic microcapsules obtained in step (2), polyvinylpyrrolidone, and α-hydroxyalkyl phenyl ketone were added to water and mixed and stirred. Then, the mixture was subjected to secondary polymerization under ultraviolet light at low temperature and low vacuum. After centrifugation, washing, and drying, high-sensitivity thermochromic microcapsules were obtained. The mass ratio of thermochromic microcapsules to polyvinylpyrrolidone was 20:1~3. The mass ratio of thermochromic microcapsules to α-hydroxyalkyl phenyl ketone was 20:1~5. The duration of secondary polymerization was 2~10 h.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of bisphenol A dye to octadecyl alcohol is 1:16~20; the mass ratio of styrene to core material is 12:3~5; the mass ratio of styrene to water is 12:150~170; the mass ratio of styrene to sodium dodecylbenzenesulfonate is 12:1.5~2; and the mass ratio of styrene to azobisisobutyronitrile initiator is 12:2~3.

3. The preparation method according to claim 1, characterized in that, In step (2), the concentration of nano-silver in the nano-silver emulsion is 0.5~1 mol / L; the mass ratio of styrene to nano-silver emulsion is 12:5~30.

4. A high color-changing sensitivity nanosilver-doped polystyrene thermochromic microcapsule prepared by the preparation method according to any one of claims 1 to 3.

5. The application of the nano-silver-doped polystyrene thermosensitive color-changing microcapsules as described in claim 4 in the textile and dyeing fields.

6. A method for preparing an antibacterial, thermosensitive, color-changing printed silk fabric, characterized in that, Includes the following steps: A printing paste is prepared by mixing and stirring a thickener, an adhesive, water, and the high color-changing sensitivity nano-silver doped polystyrene thermochromic microcapsules as described in claim 4. The paste is then used to print, pre-dry, bake, soap, and dry silk fabrics to prepare antibacterial thermochromic printed silk fabrics.

7. The method according to claim 6, characterized in that, The thickener is one of natural organic polymer thickeners, polyacrylic acid thickeners, and polyurethane thickeners; the adhesive is one of polyacrylate copolymer adhesives, butadiene emulsion copolymers, vinyl acetate copolymer adhesives, and polyurethane adhesives.

8. The method according to claim 6, characterized in that, The thermosensitive color-changing microcapsules account for 4-6% of the mass of the printing paste; the thickener accounts for 2-3% of the mass; and the binder accounts for 5-10% of the mass.

9. An antibacterial thermosensitive color-changing printed silk fabric prepared by the method according to any one of claims 6 to 8.

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