Gray fabric dyeing and printing temperature-sensitive color-changing fabric based on temperature-changing material and preparation method thereof

Abstract

The invention discloses a gray fabric dyeing and printing temperature-sensitive color-changing fabric based on a temperature-changing material and a preparation method thereof, and relates to the technical field of temperature-sensitive color-changing textile materials. The fabric comprises a gray fabric base layer, an interface compatibility layer, a dyeing layer and a composite temperature change printing layer, the composite temperature change printing layer is composed of a composite temperature change system in gradient proportion, and the system comprises surface modified photothermal conversion particles, bistable temperature-sensitive color change microcapsules and phase change energy storage particles. The bistable temperature-sensitive color-changing microcapsule is of a core-silane modified transition layer-multi-element blending wall material three-layer structure and comprises three different response types. The preparation method sequentially comprises the steps of two-stage modification pretreatment, ultrasonic-microwave synergistic dyeing, composite printing paste preparation, magnetic control paste scraping screen printing, inert gas-vacuum alternate gradient baking and plasma-assisted after-treatment, and synergistic improvement of the temperature-sensitive color change performance and the adhesion stability of the fabric is achieved. The method is suitable for intelligent wearing and functional decoration fields.

Description

Technical Field

[0001] This invention belongs to the field of thermosensitive color-changing textile materials technology, specifically relating to a thermosensitive color-changing fabric based on thermosensitive materials for dyeing and printing, and its preparation method. Background Technology

[0002] Thermochromic fabrics, capable of dynamically changing color with varying ambient temperature, have broad application prospects in smart wearables, functional decoration, and medical monitoring, making them a research hotspot in the textile materials field. These fabrics typically achieve their function by introducing thermochromic materials onto the surface of the greige fabric. The core lies in the effective integration of the thermochromic system with the fabric substrate, as well as the precise control and long-term stability of the color-changing performance. Currently, most thermochromic fabrics on the market are prepared using direct coating or conventional printing processes, forming a functional layer through simple composite thermochromic materials and adhesives to meet basic color-changing requirements.

[0003] Existing thermochromic fabrics have significant technical shortcomings. Firstly, there is insufficient interlayer compatibility. The lack of an effective transition structure between the greige fabric, dyed layer, and thermochromic functional layer results in weak interfacial adhesion. The thermochromic layer is prone to detachment during washing and friction. Simultaneously, the dyed layer and thermochromic layer interfere with each other, affecting color stability and consistency of color-changing response. Secondly, the performance of the thermochromic system is limited. Traditional thermochromic microcapsules are mostly single-structured with a single response temperature, resulting in monotonous color-changing effects. Furthermore, the wall material has poor weather resistance and temperature resistance, easily leading to color-changing failure and slow response after long-term use.

[0004] In terms of preparation processes, existing technologies also have shortcomings. Pretreatment processes only employ single chemical modification or physical treatment, making it difficult to simultaneously optimize the surface activity of the fabric and the interlayer binding sites; the dyeing and printing processes lack coordinated design, which can easily lead to the deactivation of thermochromic materials during dyeing or uneven coverage of the printed layer; the baking and finishing processes are relatively simple, mostly using single-temperature baking and conventional shaping methods, which cannot simultaneously ensure the structural integrity of thermochromic microcapsules and the adhesion strength of functional layers, making it difficult for fabrics to simultaneously meet the high-end application requirements of accurate color change, adhesion stability, and long-term durability. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a thermosensitive color-changing fabric based on thermochromic material dyeing and printing and its preparation method, which solves the problems of insufficient interlayer compatibility, limited performance of thermochromic system, and lack of synergy in preparation process that lead to poor color-changing accuracy, adhesion firmness and long-term durability in the prior art.

[0006] To address the above problems, the present invention provides the following technical solution:

[0007] A thermochromic fabric based on thermochromic materials, comprising a base fabric, an interface compatibility layer, a dyeing layer, and a composite thermochromic printing layer; the interface compatibility layer has a thickness of 3μm to 5μm; the composite thermochromic printing layer is composed of a gradient ratio composite thermochromic system, which includes surface-modified photothermal conversion particles, bistable thermochromic microcapsules, and phase change energy storage particles, with a mass ratio of 28:55:17; the bistable thermochromic microcapsules include three types: 22℃ responsive, 37℃ responsive, and 48℃ responsive, with a mass ratio of 2:5:3.

[0008] Furthermore, the bistable thermochromic microcapsule has a three-layer structure: a core layer, a silane-modified transition layer, and a multi-component blended wall material. The core layer is the thermochromic component, the transition layer is γ-glycidyl etheroxypropyltrimethoxysilane-modified silica, and the wall material is a chitosan-sodium alginate-polylactic acid blended modified bio-based material. The mass ratio of the core layer, transition layer, and wall material is 65:18:17, and the number-average molecular weight of the polylactic acid is 80,000–120,000. This three-layer structure addresses the problems of core-wall separation, poor weather resistance, and weak interlayer bonding in traditional microcapsules. The core layer, as the core of the thermochromic function, forms a tight connection with the silane-modified transition layer. The transition layer, through chemical modification, optimizes the interfacial forces, enhancing the bonding strength between the core layer and the wall material and preventing core material leakage during use. The multi-component blend wall material, through the synergistic formulation of chitosan, sodium alginate, and polylactic acid, balances biocompatibility and mechanical strength. The precise 65:18:17 mass ratio of each layer balances the color-changing response speed and structural stability, ensuring that the temperature-sensitive core component responds quickly to temperature changes while extending the microcapsule lifespan through the protective effects of the transition layer and the wall material. The number-average molecular weight of polylactic acid is controlled within the range of 80,000 to 120,000, ensuring suitable flexibility and heat resistance of the wall material, preventing cracking during baking and other processes, and simultaneously improving the washability of the temperature-changing layer.

[0009] Furthermore, the surface-modified photothermal conversion particles are barium strontium titanate-coated nano-cesium tungsten powder, the modifier is KH560 silane coupling agent, the modification temperature is 85℃, and the modification time is 90 min. The particle size of the nano-cesium tungsten powder is 80 nm to 120 nm, and the barium strontium titanate coating amount is 12% to 15% of the total particle mass. This structural design of barium strontium titanate-coated nano-cesium tungsten powder retains the excellent photothermal conversion efficiency of the nano-cesium tungsten powder while enhancing the chemical stability and weather resistance of the particles through the barium strontium titanate coating layer, preventing oxidation failure during dyeing, printing, and use. KH560 silane coupling agent, as a modifier, introduces active groups on the particle surface, enhancing the interaction with the stepwise crosslinking adhesive and the fabric substrate. The modification temperature of 85℃ and the modification time of 90 min ensure that the modification reaction is fully carried out, guaranteeing the stability of the modification effect. The 80nm to 120nm particle size range of nano-cesium tungsten powder can balance the light absorption area and the dispersibility of the paste, avoiding uneven printing layer caused by excessively large particle size or agglomeration caused by excessively small particle size; the 12% to 15% barium strontium titanate coating amount precisely controls the photothermal conversion efficiency and surface characteristics of the particles, so that photothermal conversion and temperature response are synergistic, improving the sensitivity and uniformity of fabric color change.

[0010] The thermosensitive color-changing fabric of this invention adopts a multi-layer structure design consisting of a base fabric, an interface compatibility layer, a dyeing layer, and a composite thermosensitive printing layer. The interface compatibility layer effectively connects the functional layers, eliminating the problem of weak interlayer bonding. The composite thermosensitive printing layer uses surface-modified photothermal conversion particles, bistable thermosensitive color-changing microcapsules, and phase change energy storage particles in a specific ratio. This enhances the temperature response sensitivity through photothermal conversion particles and stabilizes the temperature change range with the help of phase change energy storage particles, ensuring uniform and long-lasting color-changing effects. The bistable thermosensitive color-changing microcapsules are designed as a three-layer structure of a core-silane modified transition layer and a multi-component blended wall material, with three different gradient ratios of microcapsules with different response temperatures. This solves the problems of leakage and poor weather resistance of traditional microcapsule core materials and achieves precise color changing across multiple temperature ranges. At the same time, through the encapsulation modification of photothermal conversion particles and the precise control of the parameters of each component, particle dispersion, interfacial bonding, and functional stability are balanced, ultimately forming a thermosensitive color-changing fabric with a reasonable structure and synergistic performance.

[0011] As a general inventive concept, this invention provides a method for preparing thermosensitive color-changing fabric based on thermochromic materials through dyeing and printing, as described above, comprising the following steps:

[0012] S1. Two-stage pretreatment for modification: First, the blank is placed in a plasma treatment device, and argon gas is introduced at a flow rate of 3.5 L / min, plasma frequency of 13.56 MHz, power of 380 W, and treatment time of 6 min; then, the treated blank is placed in a composite modifier solution at a bath ratio of 1:22, treatment temperature of 65 ℃, and treatment time of 35 min. The composite modifier solution is composed of glycerol, γ-aminopropyltriethoxysilane, and quaternary ammonium salt surfactant in a mass ratio of 4.2:1:0.8, with a concentration of 92 g / L and pH value adjusted to 5.8.

[0013] S2. Ultrasonic-microwave synergistic dyeing: The fabric treated in step S1 is placed in the dyeing solution with a liquor ratio of 1:18. The synergistic action of ultrasound and microwave is initiated, with an ultrasound power of 320W, a microwave frequency of 2450MHz, a dyeing temperature of 88℃, a dyeing time of 45min, and a pH value adjusted to 5.2. The dyeing solution contains anthraquinone disperse dye, fatty alcohol polyoxyethylene ether auxiliary dye, polyethylene glycol leveling agent, and sodium citrate buffer, with a mass ratio of 10:3.2:2.1:1.5 and a concentration of 58g / L. The heating rate is 1.5℃ / min.

[0014] S3. Preparation of composite printing paste: Take 55 parts by weight of bistable thermosensitive color-changing microcapsules, 28 parts by weight of surface-modified photothermal conversion particles, 17 parts by weight of phase change energy storage particles, 36 parts by weight of stepwise crosslinking adhesive, 3.5 parts by weight of nano-montmorillonite synergist, 6 parts by weight of hydroxyethyl cellulose thickener, and 110 parts by weight of deionized water. First, stir at 800 r / min for 25 min, then heat to 60℃, increase the speed to 1200 r / min and stir for 35 min. Adjust the viscosity to 9200 mPa·s and keep warm for later use.

[0015] S4. Magnetically controlled squeegee screen printing: A stainless steel screen with a mesh count of 180 and a mesh diameter of 85μm is used. The printing pattern resolution is 400dpi. The magnetic squeegee device is started with a magnetic field strength of 0.08T, a squeegee speed of 2.8m / min, and an imprinting pressure of 0.35MPa. The paste prepared in step S3 is printed onto the surface of the fabric dyed in step S2. After printing, the fabric is pre-baked at 65℃ for 4min.

[0016] S5. Inert gas-vacuum alternating gradient baking: First, nitrogen gas is introduced at a flow rate of 2.5 L / min, and baking is carried out at 105℃ for 6 min; then, vacuum is applied to a vacuum degree of 0.06 MPa, and the temperature is raised to 145℃ for 4 min; finally, the pressure is restored to normal and nitrogen gas is introduced again, and the temperature is raised to 175℃ for 2.5 min. The heating rate at each stage is 12℃ / min.

[0017] S6. Plasma-assisted finishing: The fabric treated in step S5 is cooled to 30°C and subjected to a second low-temperature plasma treatment with an argon flow rate of 2.2 L / min, a power of 250 W, and a treatment time of 3 min; then hot air setting is performed with a wind speed of 5.5 m / s, a setting temperature of 125°C, and a setting time of 2.5 min; finally, it is washed with 28°C cold water for 6 min and air-dried naturally until the moisture content is ≤6%.

[0018] Furthermore, in step S1, the quaternary ammonium salt surfactant is hexadecyltrimethylammonium bromide. The composite modifier solution needs to be filtered through a 1μm filter membrane before use. During the treatment process, ultrasonic dispersion at a frequency of 50Hz and a power of 180W is used for assisted dispersion. Here, hexadecyltrimethylammonium bromide can enhance the active sites and charge density on the fabric surface, improving the adsorption efficiency of the composite modifier; 1μm filter membrane filtration can remove fine impurities in the solution, avoiding defects in subsequent processes; ultrasonic dispersion at a frequency of 50Hz and a power of 180W allows the composite modifier to be evenly distributed in the bath, ensuring consistent modification effects in all areas of the fabric, and laying a uniform and stable surface foundation for the firm bonding of the subsequent dyeing layer and thermochromic printing layer.

[0019] Furthermore, in step S2, the concentration of sodium citrate buffer in the dyeing solution is 8 g / L. After dyeing, the solution is cooled to 42°C at a rate of 0.8°C / min, while maintaining ultrasonic activity during cooling, with the power reduced to 150W. This specific concentration of sodium citrate buffer stabilizes the pH environment of the dyeing solution, preventing pH changes from affecting the binding efficiency of the dye to the fabric and the stability of the thermochromic components. The slow cooling rate of 0.8°C / min allows the dye to fully diffuse and fix within the fiber, reducing color difference and uneven coloring in the dyed layer. Maintaining low-power ultrasonic activity during the cooling stage promotes the desorption of residual dye, prevents dye accumulation on the fabric surface, and protects the surface activity of the fabric required for subsequent printing processes, ensuring the compatibility of the dyed layer and the thermochromic printing layer.

[0020] Furthermore, in step S3, the stepwise crosslinking adhesive is a compound of waterborne polyurethane, epichlorohydrin crosslinking agent, polyamide epichlorohydrin resin, and acrylate reactive emulsifier in a mass ratio of 68:22:6:4. The nano-montmorillonite synergist has a particle size of 50nm to 80nm and a cation exchange capacity of 95mmol / 100g. Here, the waterborne polyurethane, epichlorohydrin crosslinking agent, polyamide epichlorohydrin resin, and acrylate reactive emulsifier are compounded in a specific ratio to achieve a multi-stage crosslinking reaction. This ensures the fluidity of the paste during the printing process and forms a high-strength crosslinking network after baking, improving the adhesion between the thermochromic layer and the dyed layer. The particle size and cation exchange capacity parameters of the nano-montmorillonite synergist are designed to enhance the thixotropy and dispersion stability of the paste, preventing component agglomeration that leads to uneven printing. Simultaneously, it improves the abrasion resistance and washability of the printed layer, extending the fabric's service life.

[0021] Furthermore, in step S4, the squeegee angle of the magnetic squeegee device is 65°, the squeegee strokes are performed twice, and the interval between the two squeegee strokes is 15 seconds. The pre-baking process uses an environment with a humidity of 45%. This 65° squeegee angle and the two-stroke design ensure that the paste fully fills the mesh and is evenly transferred to the fabric surface, avoiding missed printing or excessive paste thickness. The 15-second squeegee interval allows the paste from the previous stroke to initially wet the fabric, improving the bonding effect of the second stroke. The 45% pre-baking humidity balances the drying rate of the paste, preventing cracking of the printed layer or pattern deformation due to rapid drying. Simultaneously, it creates suitable conditions for the cross-linking reaction in the subsequent gradient baking, ensuring a tight bond between the printed layer and the dyed layer.

[0022] Furthermore, in step S5, the vacuum stage involves releasing the pressure to 0.02 MPa every 1 minute, maintaining it for 10 seconds, and then pumping it back down to 0.06 MPa. The initial relative humidity of the baking environment is controlled at 32%–36%. This pressure release and pumping operation every minute removes residual gas from the fabric and printing layer, preventing interlayer peeling or defects in the printing layer caused by air bubbles. The initial relative humidity of 32% to 36% controls the rate of moisture evaporation during the baking process, ensuring that the stepwise crosslinking adhesive is fully crosslinked and cured, while preventing the temperature-sensitive microcapsules from cracking due to rapid dehydration and causing leakage of the core material. At the same time, the alternating environment of inert gas and vacuum reduces the oxidation failure of the temperature-sensitive components, balancing adhesion strength and color-changing function stability.

[0023] Furthermore, in step S6, the cold water washing uses flowing water at a speed of 0.8 m / s, the drying environment temperature is 25℃~28℃, the relative humidity is 50%~60%, and the drying time is controlled at 8h~10h. This combination of flowing water and a specific water flow speed effectively removes residual sizing agents, unfixed dyes, and impurities from the fabric surface, preventing residual substances from affecting the fabric's feel or causing uneven color change. The temperature, humidity, and time parameters of the drying environment are designed to prevent the fabric from shrinking or deforming due to excessively rapid drying, or the temperature-sensitive layer from cracking, ensuring that the fabric's moisture content meets the standards.

[0024] This invention discloses a method for preparing thermosensitive color-changing fabrics based on thermochromic materials through dyeing and printing. The pretreatment employs a two-stage design to enhance the surface activity and binding sites of the fabric. The dyeing process combines ultrasound and microwave synergy to ensure uniform dye fixation without affecting the stability of the thermochromic components. The printing stage utilizes magnetron sputtering technology to improve the uniformity of sizing transfer. The baking process employs an alternating gradient of inert gas and vacuum to prevent the deactivation of thermochromic microcapsules and promote cross-linking and curing. The finishing process introduces plasma-assisted treatment to further strengthen interlayer bonding. Simultaneously, by rationally setting key parameters such as reagent ratios and treatment conditions in each process, the method ensures smooth transitions and mutual compatibility between processes, avoiding interference and ultimately achieving a synergistic improvement in the fabric's color-changing performance and structural stability.

[0025] Compared with the prior art, the advantages of the present invention are as follows:

[0026] (1) This invention effectively optimizes the interfacial forces between the base layer of the fabric, the dyeing layer and the composite thermochromic printing layer by setting an interface compatibility layer, a two-stage modification pretreatment and plasma-assisted finishing, and a multi-component synergistic effect of stepwise crosslinking adhesive. It solves the problems of easy shedding of the thermochromic layer and interlayer interference in traditional fabrics, and enhances the abrasion resistance and washability of the fabric.

[0027] (2) The gradient ratio of three bistable thermosensitive color-changing microcapsules with different response temperatures in the composite thermo-changing system of the present invention, combined with the synergistic effect of surface-modified photothermal conversion particles and phase change energy storage particles, not only achieves accurate color-changing response in multiple temperature ranges, but also enhances color-changing sensitivity through photothermal conversion, enriching the color-changing effect and visual experience of the fabric.

[0028] (3) The three-layer structure of the bistable thermosensitive color-changing microcapsule of the present invention, which consists of a core-silane modified transition layer and a multi-component blended wall material, combined with an inert gas-vacuum alternating gradient baking process, effectively avoids leakage and oxidation failure of the thermosensitive core material. At the same time, the polylactic acid modified wall material and the photothermal particles coated with barium strontium titanate improve the weather resistance of the system, ensuring that the fabric can maintain stable color-changing performance after long-term use.

[0029] (4) The ultrasonic-microwave synergistic dyeing process of the present invention ensures uniform fixation of dyes. The precise parameter design of magnetic control scraping screen printing avoids problems such as missing printing and paste accumulation. Gradient baking and controllable drying conditions reduce fabric shrinkage and deformation and cracking of printing layer, making the fabric uniform in color, clear in pattern, good in hand feel, and with high production consistency.

[0030] (5) The synergistic design of photothermal conversion, thermochromic color change and phase change energy storage functions of the present invention enables the fabric to not only dynamically change color with temperature changes, but also stabilize the temperature change range through phase change particles, adapting to the needs of multiple fields such as smart wearables, functional decoration, and medical monitoring, thus expanding the application scenarios of thermochromic fabrics. Attached Figure Description

[0031] Figure 1 This is a flowchart of the present invention regarding a thermosensitive color-changing fabric based on thermochromic materials for dyeing and printing, and its preparation method. Detailed Implementation

[0032] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0033] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0034] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0035] Example 1

[0036] refer to Figure 1This invention discloses a thermochromic fabric based on thermochromic materials, comprising a base fabric, an interface compatibility layer, a dyeing layer, and a composite thermochromic printing layer. The interface compatibility layer has a thickness of 4 μm. The composite thermochromic printing layer is composed of a gradient-proportioned composite thermochromic system, which includes surface-modified photothermal conversion particles, bistable thermochromic microcapsules, and phase change energy storage particles in a mass ratio of 28:55:17. The bistable thermochromic microcapsules include three types: 22°C responsive, 37°C responsive, and 48°C responsive, in a mass ratio of 2:5:3. The bistable thermochromic microcapsules are nucleo-silane modified transition materials. The three-layer structure of the multi-component blend wall material consists of a core layer composed of a thermosensitive color-changing component, a transition layer of γ-glycidyl etheroxypropyltrimethoxysilane modified silica, and a wall material of chitosan-sodium alginate-polylactic acid blend modified bio-based material. The mass ratio of the core layer, transition layer, and wall material is 65:18:17, and the number average molecular weight of polylactic acid is 100,000. The surface-modified photothermal conversion particles are barium strontium titanate-coated nano-cesium tungsten powder, modified by KH560 silane coupling agent, modified at 85℃ for 90 min, with a particle size of 100 nm and a barium strontium titanate coating amount of 13% of the total particle mass.

[0037] The method for preparing the thermosensitive color-changing fabric in this embodiment includes the following steps:

[0038] S1. Two-stage pretreatment for modification: First, the blank is placed in a plasma treatment device, and argon gas is introduced at a flow rate of 3.5 L / min, plasma frequency of 13.56 MHz, power of 380 W, and treatment time of 6 min. Then, the treated blank is placed in a composite modifier solution at a bath ratio of 1:22, treatment temperature of 65 ℃, and treatment time of 35 min. The composite modifier solution is composed of glycerol, γ-aminopropyltriethoxysilane, and hexadecyltrimethylammonium bromide in a mass ratio of 4.2:1:0.8, with a concentration of 92 g / L and pH adjusted to 5.8. The composite modifier solution is filtered through a 1 μm filter membrane before use. During the treatment, ultrasonic dispersion at a frequency of 50 Hz and a power of 180 W is used.

[0039] S2. Ultrasonic-microwave synergistic dyeing: The fabric treated in step S1 is placed in the dyeing solution with a liquor ratio of 1:18. The synergistic action of ultrasound and microwave is initiated, with an ultrasound power of 320W, a microwave frequency of 2450MHz, a dyeing temperature of 88℃, a dyeing time of 45min, and the pH value adjusted to 5.2. The dyeing solution contains anthraquinone disperse dye, fatty alcohol polyoxyethylene ether auxiliary dye, polyethylene glycol leveling agent, and sodium citrate buffer, with a mass ratio of 10:3.2:2.1:1.5 and a concentration of 58g / L. The heating rate is 1.5℃ / min, and the concentration of sodium citrate buffer is 8g / L. During the dyeing process, the fabric is stirred once every 10min at a stirring speed of 200r / min. After dyeing, the fabric is cooled to 42℃ at a cooling rate of 0.8℃ / min. Ultrasonic action is maintained during the cooling process, and the power is reduced to 150W.

[0040] S3. Preparation of composite printing paste: Take 55 parts by weight of bistable thermosensitive color-changing microcapsules, 28 parts by weight of surface-modified photothermal conversion particles, 17 parts by weight of phase change energy storage particles, 36 parts by weight of stepwise crosslinking adhesive, 3.5 parts by weight of nano-montmorillonite synergist, 6 parts by weight of hydroxyethyl cellulose thickener, and 110 parts by weight of deionized water. First, stir at 800 r / min for 25 min, then heat to 60℃, increase the speed to 1200 r / min and stir for 35 min. Nitrogen protection is used during stirring, with a nitrogen flow rate of 1 L / min. Adjust the viscosity to 9200 mPa·s and keep at 60℃ for later use. The stepwise crosslinking adhesive is compounded by waterborne polyurethane, epichlorohydrin crosslinking agent, polyamide epichlorohydrin resin and acrylate reactive emulsifier in a mass ratio of 68:22:6:4. The nano-montmorillonite synergist has a particle size of 60 nm and a cation exchange capacity of 95 mmol / 100 g.

[0041] S4. Magnetron squeegee screen printing uses a stainless steel screen with a mesh count of 180, a mesh diameter of 85μm, a printing pattern resolution of 400dpi, and screen tension controlled at 25N / cm. The magnetron squeegee device is activated with a magnetic field strength of 0.08T, a squeegee blade angle of 65°, a squeegee speed of 2.8m / min, an imprinting pressure of 0.35MPa, and two squeegee passes with a 15s interval between the two passes. The paste prepared in step S3 is then printed onto the surface of the fabric dyed in step S2. After printing, the fabric is pre-baked at 65℃ for 4 minutes, with the humidity of the pre-baking environment controlled at 45%.

[0042] S5. Inert gas-vacuum alternating gradient baking: First, nitrogen gas is introduced at a flow rate of 2.5 L / min, and baking is carried out at 105℃ for 6 min; then, vacuum is evacuated to a vacuum degree of 0.06 MPa, and the temperature is raised to 145℃ for 4 min. During the vacuum stage, the pressure is released to 0.02 MPa every 1 min, maintained for 10 s, and then evacuated to 0.06 MPa again; finally, atmospheric pressure is restored and nitrogen gas is introduced again, and the temperature is raised to 175℃ for 2.5 min. The heating rate for each stage is 12℃ / min, and the initial relative humidity of the baking environment is controlled at 34%.

[0043] S6. Plasma-assisted finishing: The fabric treated in step S5 is naturally cooled to 30°C, and then subjected to a second low-temperature plasma treatment with an argon flow rate of 2.2 L / min, a power of 250 W, and a treatment time of 3 min. Then, it is hot-air set at a wind speed of 5.5 m / s, a setting temperature of 125°C, and a setting time of 2.5 min. Finally, it is washed with 28°C cold water (deionized water) for 6 min using running water at a flow rate of 0.8 m / s. After washing, it is air-dried at an ambient temperature of 26°C and a relative humidity of 55% for 9 h.

[0044] Example 2

[0045] The difference between this embodiment and Embodiment 1 is that the mass ratio of surface-modified photothermal conversion particles, bistable thermochromic microcapsules, and phase change energy storage particles in the composite thermochromic system is adjusted to 30:52:18; the mass ratio of 22℃-responsive, 37℃-responsive, and 48℃-responsive microcapsules in the bistable thermochromic microcapsules is adjusted to 3:4:3; and the heating rate of each stage of the alternating gradient baking of inert gas and vacuum is adjusted to 10℃ / min. The remaining fabric structure, preparation process, and parameters are the same as in Embodiment 1.

[0046] Example 3

[0047] The difference between this embodiment and Example 1 is that the modifier for the surface-modified photothermal conversion particles is replaced with KH550 silane coupling agent, and the proportion of polyamide epichlorohydrin resin in the stepwise crosslinking adhesive is adjusted to 8%, with the corresponding mass ratio of each component of the stepwise crosslinking adhesive being 66:22:8:4. The remaining fabric structure, preparation process, and parameters are the same as in Example 1.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that the interfacial compatibility layer of the fabric is removed, and only the base fabric, dyeing layer, and composite thermochromic printing layer are retained. The remaining fabric structure, preparation process and parameters are the same as those in Example 1.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 1 is that the bistable thermosensitive color-changing microcapsules are replaced with ordinary thermosensitive microcapsules with a single chitosan wall material. The ordinary thermosensitive microcapsules have a core-wall bilayer structure, no silane-modified transition layer, and contain only one type of 37°C responsive microcapsule. The remaining fabric structure, preparation process, and parameters are the same as in Example 1.

[0052] Comparative Example 3

[0053] The difference between this comparative example and Example 1 is that the two-stage pretreatment for modification is replaced with immersion in a composite modifier solution only, and the plasma pretreatment step is removed. The remaining fabric structure, preparation process and parameters are the same as in Example 1.

[0054] Comparative Example 4

[0055] The difference between this comparative example and Example 1 is that the ultrasonic-microwave synergistic dyeing was replaced with conventional water bath dyeing, and the ultrasonic and microwave auxiliary effects were removed. The remaining fabric structure, preparation process and parameters are the same as those in Example 1.

[0056] Comparative Example 5

[0057] The difference between this comparative example and Example 1 is that the magnetic control screen printing is replaced with conventional mechanical screen printing, and the magnetic field assistance is removed. The rest of the fabric structure, preparation process and parameters are the same as those in Example 1.

[0058] Comparative Example 6

[0059] The difference between this comparative example and Example 1 is that the alternating gradient baking of inert gas and vacuum is replaced with baking at a single temperature of 150°C for 8 minutes, and the introduction of inert gas and vacuum operation are removed. The rest of the fabric structure, preparation process and parameters are the same as those in Example 1.

[0060] The thermosensitive color-changing fabrics in Examples 1-3 and Comparative Examples 1-6 were tested using the following methods:

[0061] 1. Interlayer bonding strength (washing resistance): Using a standard washing program with 50℃ water temperature and regular detergent, the maximum number of washes was recorded as the criterion for no peeling of the thermochromic layer and no significant attenuation of the color-changing effect.

[0062] 2. Color change response temperature range: The color change of the fabric was tested at 22℃, 37℃ and 48℃ respectively, and the number of temperature ranges in which the effective color change could be stably displayed was counted;

[0063] 3. Weather resistance and color change stability: After 1000h of UV aging test, the initial color change effect of the fabric is compared and rated from 1 to 5 according to the degree of no fading and no slow response (5th grade is the best).

[0064] 4. Pattern clarity: Visually observe whether the printed edges are blurry, whether there are any missing prints or ink buildup, and rate the clarity on a scale of 1-5 (5 being the best).

[0065] 5. Color uniformity: Visually observe whether there is color difference, color spots, or uneven color change in the temperature-sensitive layer, and rate the uniformity from 1 to 5 (5 being the best).

[0066] Table 1: Experimental Results of Examples and Comparative Examples

[0067] Case Interlayer bonding strength (wash resistance / cycle) Color-changing response temperature ranges (number) Weather resistance and color change stability Pattern clarity Color uniformity Example 1 ≥50 3 5 5 5 Example 2 ≥48 3 5 5 5 Example 3 ≥45 3 4 5 5 Comparative Example 1 ≤30 3 4 5 5 Comparative Example 2 ≥40 1 2 5 5 Comparative Example 3 ≤35 3 3 4 4 Comparative Example 4 ≥40 3 4 5 3 Comparative Example 5 ≥40 3 4 3 4 Comparative Example 6 ≤38 3 2 4 5

[0068] In summary, as shown in Table 1, the embodiment is significantly superior to the comparative example in key performance indicators such as interlayer bonding strength, number of color change response temperature ranges, color change stability after weathering, pattern clarity, and color uniformity.

[0069] Comparative Example 1, lacking an interface compatibility layer, suffered from insufficient interfacial forces between functional layers, resulting in a significant decrease in interlayer bonding strength. Comparative Example 2, using ordinary thermochromic microcapsules with a single chitosan wall material, lacked a silane-modified transition layer for protection and was only a single-response temperature type. The core material was prone to leakage and had poor weather resistance, thus resulting in a limited color-changing response temperature range and extremely poor stability after weathering. Comparative Example 3, by omitting plasma pretreatment, had insufficient active sites on the fabric surface and uneven modification effects, affecting interlayer bonding strength, weather resistance stability, and color uniformity. Comparative Example 4, using conventional water bath dyeing, lacked the synergistic effect of ultrasound and microwave, leading to uneven dye fixation and a low level of color uniformity. Comparative Example 5, using conventional mechanical scraping printing, lacked magnetic field assistance, making it difficult to ensure uniform paste transfer, resulting in blurred printing edges and a significant decrease in pattern clarity. Comparative Example 6, using single-temperature baking without alternating protection from inert gas and vacuum, caused the thermochromic microcapsules to easily fail due to insufficient cross-linking or oxidation, resulting in poor interlayer bonding strength and color-changing stability after weathering.

[0070] Example 1 adopts a complete technical solution, with a multi-layer structure, a composite temperature change system, and a synergistic process and key parameters precisely matched, achieving optimal performance indicators.

[0071] Example 2 only slightly adjusts the core parameters to maintain a process compatibility similar to Example 1, so there is no significant attenuation in various performance indicators.

[0072] In Example 3, due to the replacement of the surface modifier and the slight adjustment of the proportion of the adhesive components, the material compatibility decreased slightly, resulting in a slight reduction in interlayer bonding strength and weather resistance and color change stability, but still maintaining an excellent level.

Claims

1. A thermosensitive color-changing fabric based on thermochromic materials for dyeing and printing, characterized in that: The material includes a base fabric, an interface compatibility layer, a dyeing layer, and a composite thermochromic printing layer. The interface compatibility layer has a thickness of 3μm to 5μm. The composite thermochromic printing layer is composed of a gradient ratio composite thermochromic system, which includes surface-modified photothermal conversion particles, bistable thermosensitive color-changing microcapsules, and phase change energy storage particles in a mass ratio of 28:55:

17. The bistable thermosensitive color-changing microcapsules include three types: 22℃ responsive, 37℃ responsive, and 48℃ responsive, in a mass ratio of 2:5:

3.

2. The thermosensitive color-changing fabric based on thermochromic materials for dyeing and printing as described in claim 1, characterized in that: The bistable thermosensitive color-changing microcapsule has a three-layer structure: a core layer, a silane-modified transition layer, and a multi-component blended wall material. The core layer is the thermosensitive color-changing component, the transition layer is γ-glycidyl etheroxypropyltrimethoxysilane-modified silica, and the wall material is a chitosan-sodium alginate-polylactic acid blended modified bio-based material. The mass ratio of the core layer, transition layer, and wall material is 65:18:17, and the number-average molecular weight of the polylactic acid is 80,000 to 120,000.

3. The thermosensitive color-changing fabric based on thermochromic materials for dyeing and printing as described in claim 1, characterized in that: The surface-modified photothermal conversion particles are barium strontium titanate-coated nano-cesium tungsten powder, the modifier is KH560 silane coupling agent, the modification temperature is 85℃, the modification time is 90min, the particle size of the nano-cesium tungsten powder is 80nm~120nm, and the amount of barium strontium titanate coating is 12%~15% of the total mass of the particles.

4. A method for preparing thermosensitive color-changing fabric by dyeing and printing on greige fabric based on thermochromic materials, characterized in that: Includes the following steps, S1. Two-stage pretreatment for modification: First, the blank is placed in a plasma treatment device, and argon gas is introduced at a flow rate of 3.5 L / min, plasma frequency of 13.56 MHz, power of 380 W, and treatment time of 6 min; then, the treated blank is placed in a composite modifier solution at a bath ratio of 1:22, treatment temperature of 65 ℃, and treatment time of 35 min. The composite modifier solution is composed of glycerol, γ-aminopropyltriethoxysilane, and quaternary ammonium salt surfactant in a mass ratio of 4.2:1:0.8, with a concentration of 92 g / L and pH value adjusted to 5.

8. S2. Ultrasonic-microwave synergistic dyeing: The fabric treated in step S1 is placed in the dyeing solution with a liquor ratio of 1:

18. The synergistic action of ultrasound and microwave is initiated, with an ultrasound power of 320W, a microwave frequency of 2450MHz, a dyeing temperature of 88℃, a dyeing time of 45min, and a pH value adjusted to 5.

2. The dyeing solution contains anthraquinone disperse dye, fatty alcohol polyoxyethylene ether auxiliary dye, polyethylene glycol leveling agent, and sodium citrate buffer, with a mass ratio of 10:3.2:2.1:1.5 and a concentration of 58g / L. The heating rate is 1.5℃ / min. S3. Preparation of composite printing paste: Take 55 parts by weight of bistable thermosensitive color-changing microcapsules, 28 parts by weight of surface-modified photothermal conversion particles, 17 parts by weight of phase change energy storage particles, 36 parts by weight of stepwise crosslinking adhesive, 3.5 parts by weight of nano-montmorillonite synergist, 6 parts by weight of hydroxyethyl cellulose thickener, and 110 parts by weight of deionized water. First, stir at 800 r / min for 25 min, then heat to 60℃, increase the speed to 1200 r / min and stir for 35 min. Adjust the viscosity to 9200 mPa·s and keep warm for later use. S4. Magnetically controlled squeegee screen printing: A stainless steel screen with a mesh count of 180 and a mesh diameter of 85μm is used. The printing pattern resolution is 400dpi. The magnetic squeegee device is started with a magnetic field strength of 0.08T, a squeegee speed of 2.8m / min, and an imprinting pressure of 0.35MPa. The paste prepared in step S3 is printed onto the surface of the fabric dyed in step S2. After printing, the fabric is pre-baked at 65℃ for 4min. S5. Inert gas-vacuum alternating gradient baking: First, nitrogen gas is introduced at a flow rate of 2.5 L / min, and baking is carried out at 105℃ for 6 min; then, vacuum is applied to a vacuum degree of 0.06 MPa, and the temperature is raised to 145℃ for 4 min; finally, the pressure is restored to normal and nitrogen gas is introduced again, and the temperature is raised to 175℃ for 2.5 min. The heating rate at each stage is 12℃ / min. S6. Plasma-assisted finishing: The fabric treated in step S5 is cooled to 30°C and subjected to a second low-temperature plasma treatment with an argon flow rate of 2.2 L / min, a power of 250 W, and a treatment time of 3 min; then hot air setting is performed with a wind speed of 5.5 m / s, a setting temperature of 125°C, and a setting time of 2.5 min; finally, it is washed with 28°C cold water for 6 min and air-dried naturally until the moisture content is ≤6%.

5. The method for preparing a thermosensitive color-changing fabric based on thermochromic materials through dyeing and printing as described in claim 4, characterized in that: In step S1, the quaternary ammonium salt surfactant is hexadecyltrimethylammonium bromide. The composite modifier solution needs to be filtered through a 1μm filter membrane before use. During the treatment process, ultrasonic dispersion with a frequency of 50Hz and a power of 180W is used.

6. The method for preparing a thermosensitive color-changing fabric based on thermochromic materials through dyeing and printing as described in claim 4, characterized in that: In step S2, the concentration of sodium citrate buffer in the staining solution is 8 g / L. After staining, the solution is cooled to 42°C at a cooling rate of 0.8°C / min. During the cooling process, sonication is maintained, and the power is reduced to 150W.

7. The method for preparing a thermosensitive color-changing fabric based on thermochromic materials through dyeing and printing as described in claim 4, characterized in that: In step S3, the stepwise crosslinking adhesive is composed of waterborne polyurethane, epichlorohydrin crosslinking agent, polyamide epichlorohydrin resin, and acrylate reactive emulsifier in a mass ratio of 68:22:6:

4. The nano-montmorillonite synergist has a particle size of 50nm to 80nm and a cation exchange capacity of 95mmol / 100g.

8. The method for preparing a thermosensitive color-changing fabric based on thermochromic materials through dyeing and printing as described in claim 4, characterized in that: In step S4, the angle of the scraper blade of the magnetic scraper is 65°, the number of scrapings is 2, the interval between the two scrapings is 15s, and the ambient atmosphere with a humidity of 45% is used during the pre-drying process.

9. The method for preparing a thermosensitive color-changing fabric based on thermochromic materials through dyeing and printing, as described in claim 4, is characterized in that: In step S5, the vacuum stage is maintained by releasing the pressure to 0.02 MPa every 1 minute, maintaining it for 10 seconds, and then pumping it back down to 0.06 MPa. The initial relative humidity of the baking environment is controlled at 32% to 36%.

10. The method for preparing a thermosensitive color-changing fabric based on thermochromic materials through dyeing and printing as described in claim 4, characterized in that: In step S6, cold water washing uses flowing water with a flow rate of 0.8 m / s. The drying environment temperature is 25℃~28℃, the relative humidity is 50%~60%, and the drying time is controlled between 8h and 10h.

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