Intelligent printing and dyeing method of temperature-sensitive color-changing silk fabric and fabric

Abstract

The invention relates to the technical field of silk fabric preparation, in particular to an intelligent printing and dyeing method of a temperature-sensitive color-changing silk fabric and the fabric. Silkworm silk fabric is subjected to conventional refining and bleaching, then ultrasonic-assisted compound enzyme system surface modification treatment is performed, and the temperature-sensitive color-changing silk fabric is obtained. The preparation method comprises the following steps: performing high-shear dispersion and vacuum defoamation on components comprising a temperature-sensitive pigment system, a microcapsule-encapsulated phase change material, inorganic nanoparticles and a water-based adhesive to prepare the ink; piezoelectric digital printing equipment is adopted, printing ink is applied to a designated area of the silk fabric in a layered or juxtaposed mode, the printed and dyed fabric is subjected to two-stage stepped curing treatment, and a near-infrared radiation and hot air convection combined energy source is adopted for curing; the cured fabric is sequentially subjected to wet finishing treatment including the steps of soaping, rinsing and soft finishing, the performance of a silk body is kept while complex color changing of the pattern and directional response of a temperature zone are achieved, and the stability and function expression precision of the color-changing pattern are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silk fabric preparation, and relates to an intelligent printing and dyeing method of temperature-sensitive color-changing silk fabric and the fabric. BACKGROUND

[0002] Silk is a high-end natural fiber material, which is widely used in clothing, household textiles and handicrafts due to its unique luster, soft hand feeling and good air permeability. Traditional silk printing and dyeing process mainly adopts dyeing or silk screen printing, etc. Such technology has certain advantages in realizing stable presentation of color patterns, but the dyeing result is usually fixed and irreversible, lacking interactivity and functionality, which is difficult to meet the growing demand of current market for personalized, intelligent and functional textiles.

[0003] In recent years, temperature-sensitive color-changing materials have been widely studied for the development of intelligent textiles due to their reversible color-changing characteristics with environmental temperature changes, especially for creating fabric patterns with dynamic visual effects. By combining temperature-sensitive ink or paint with fabric, the "show-hide" switching effect of the pattern can be achieved, giving the fabric certain information expression, emotional response or environmental perception ability. However, the application of temperature-sensitive color-changing technology in the printing and dyeing process of natural silk fabric has not been reported.

[0004] The existing temperature-sensitive color-changing pigments or inks have poor adhesion on silk surface, are sensitive to washing, rubbing, light and humidity, and are prone to color drift, fading or falling off, making it difficult to achieve long-term stable color-changing effect.

[0005] The commonly used temperature-sensitive pigments have fixed color-changing points, lack of fine and adjustable temperature control means, and are difficult to flexibly set the color-changing threshold according to different use scenarios (such as human body temperature response, indoor and outdoor temperature difference response, etc.), which is not conducive to the personalized customization of product functions.

[0006] Traditional temperature-sensitive pattern printing is mostly for overall color change, which cannot realize different colors in different areas of the pattern at different temperatures, limiting the freedom of pattern design and visual levels, and making it difficult to meet the needs of users for complex color-changing effects.

[0007] Temperature-sensitive ink usually contains polymer carriers and functional particles, which may adversely affect the natural properties of silk such as softness, luster, drape and air permeability if not handled properly, thereby reducing the high-end feel and comfort of the fabric.

[0008] Therefore, there is an urgent need for a new temperature-sensitive color-changing silk printing and dyeing method. SUMMARY

[0009] To this end, the present application aims to provide an intelligent printing and dyeing method of temperature-sensitive color-changing silk fabric and the fabric, which can realize complex pattern color change and temperature zone directional response while maintaining the performance of silk body and significantly improving the stability of color-changing pattern and the accuracy of functional expression.

[0010] To achieve the above object, the present application provides the following technical solutions:

[0011] An intelligent printing and dyeing method of temperature-sensitive color-changing silk fabric, comprising the following steps:

[0012] S1. Fabric pretreatment: The mulberry silk fabric is subjected to conventional refining and bleaching, and then subjected to composite enzyme system surface modification treatment under the assistance of ultrasonic waves, until the water contact angle of the fabric surface is less than or equal to 30°;

[0013] S2. Functional temperature-sensitive ink preparation: the components including temperature-sensitive pigment system, microcapsule-encapsulated phase change material, inorganic nanoparticles and water-based adhesive are prepared into an ink with a shear rate of 100 s -1 and a viscosity of 8-20 mPa·s through high shear dispersion and vacuum degassing;

[0014] S3. High-precision digital printing and dyeing: using a piezoelectric digital printing equipment, the ink prepared in step S2 is applied to the designated area of the silk fabric in a layered or juxtaposed manner with a resolution of not less than 600 dpi;

[0015] S4. Composite energy curing: the printed and dyed fabric is subjected to two-stage stepwise curing treatment, and the curing adopts a combined energy of near-infrared radiation and hot air convection;

[0016] S5. Finishing: the cured fabric is subjected to wet finishing treatment including soaping, rinsing and softening finishing steps in sequence.

[0017] The present application is further provided that: the composite enzyme system surface modification treatment in step S1 is carried out in a phosphate buffer solution, the composite enzyme system contains sericinase and alkaline protease, the total concentration is 0.5%-2.0%(v / v), the treatment temperature is 30-45℃, the pH value is 7.5-9.0, and it is assisted by ultrasonic waves with a frequency of 25-40 kHz, and the treatment time is 30-60 minutes.

[0018] The present application is further provided that: the temperature-sensitive pigment in step S2 is encapsulated in a microcapsule, the capsule wall material of the microcapsule is polyurethane, and the pigment system contains pigments with thermal hysteresis effect, and there is a temperature difference of 2℃ to 8℃ between the heating color-changing point and the cooling recovery color-changing point.

[0019] The present application is further configured that the inorganic nanoparticles in step S2 are at least one selected from nano-silica, nano-titania or nano-alumina, with an average particle size of 20-100 nm, and are surface-modified with a silane coupling agent before use.

[0020] The present application is further configured that the microcapsule-encapsulated phase change material in step S2 has a core substance of a mixture of n-alkanes with a chain length of C18-C28, with a latent heat of phase change greater than 150 J / g, and a phase change core temperature set between 26-34°C.

[0021] The present application is further configured that the high-precision digital printing in step S3 is to form a hidden pattern that appears after being revealed on the fabric, and the embodiment specifically includes the following steps executed in sequence:

[0022] First, take the ink prepared in step S2, which has the property of presenting a first effective color in a first temperature interval, and changing into a second color in a second temperature interval, and the CIELAB color difference value ΔE between the first and second effective colors is ≥20;

[0023] After printing and complete curing of the ink on the reference silk fabric sample, use a spectrophotometer to measure the surface color value as the target color in the first temperature interval;

[0024] Based on the measured target color value, prepare a background ink containing a conventional non-thermochromic colorant and the same water-based aliphatic polyurethane binder as the temperature-sensitive ink, and the color difference value ΔE between the color of the background ink after curing and the target color is ≤1.5;

[0025] Print the reversible temperature-sensitive ink into a hidden pattern on the predetermined position of the silk fabric;

[0026] Perform an intermediate curing treatment on the fabric printed with the hidden pattern at a temperature of 50-70°C for 2-5 minutes;

[0027] Using a visual alignment system, print the background ink on the adjacent or surrounding area of the hidden pattern, and ensure that the edges of the background pattern and the edges of the hidden pattern achieve an overlap of ≤0.1 mm. The present application is further configured that the two-stage stepwise curing treatment in step S4 includes the following steps:

[0028] The first stage is to uniformly pre-cure the entire fabric at a temperature of 60-80°C by a combination of hot air and near-infrared (NIR) radiation with an intensity set to 5-15 kW / m², for a time of 10-20 minutes;

[0029] The second stage lasts for 20-30 minutes, by taking the following steps:

[0030] Calculating ink load: before curing, the pattern data of step S3 is obtained, and the theoretical application volume of ink of each area of the pattern is calculated;

[0031] Matching process parameters: according to the calculated ink load value, independent second-stage curing parameters are matched for each area of the pattern, wherein high near-infrared radiation power and temperature are matched for the high-ink-load area, the temperature is 125-130℃, low near-infrared radiation power and temperature are matched for the low-ink-load area, the temperature is 110-115℃, and the hot air flow rate is controlled at 0.2-0.5m / s.

[0032] The present application is further provided that: the wet finishing treatment in step S5 has the following specific process conditions:

[0033] Soaping treatment: a non-ionic soaping agent with a concentration of 1-3g / L is used, and the treatment is carried out at 40-50℃ for 10-15 minutes;

[0034] Soft finishing treatment: a hydrophilic silicone or modified amino silicone oil softener with a concentration of 10-30g / L is used, and the treatment is carried out at 30-40℃ for 15-20 minutes, and finally the pH value of the finished fabric is controlled at 6.0-7.5.

[0035] A kind of warm sensitive color-changing silk fabric is prepared by the intelligent printing and dyeing method, and the fabric has a functional pattern layer,

[0036] The functional pattern layer includes a hidden pattern area and a background pattern area; the hidden pattern area includes the first microcapsule component; the background pattern area includes a conventional non-color-changing colorant, and the color difference ΔE between the color of the first microcapsule component and the color of the background pattern area at the first temperature interval is less than or equal to 1.5.

[0037] Compared with the prior art, the present application has the following advantages:

[0038] By integrating temperature-sensitive pigments and phase change materials, controllable color changes within a specific temperature range (26-34℃) are achieved, and the temperature-sensitive pigments have a certain thermal hysteresis effect (2-8℃), providing more dynamic and interesting designs, such as "hidden and visible" patterns or temperature memory effects.

[0039] Combined with high-precision digital printing and dyeing technology and precise control of background ink color (ΔE≤1.5), the hidden pattern can be finely made, and the visual concealment of the pattern at a specific temperature can be ensured, improving the technological sense and added value of the product.

[0040] Ultrasonic-assisted complex enzyme treatment significantly improves the hydrophilicity of silk fabric, providing a better basis for ink adhesion and penetration.

[0041] The two-stage ladder curing, especially the gradient temperature and NIR radiation control in the second stage, can effectively solve the uneven curing problem in different ink amount areas, improve the curing efficiency and overall product quality. The introduction of NIR radiation accelerates the curing process and reduces energy consumption.

[0042] The introduction of modified inorganic nanoparticles significantly improves the wash fastness and rubbing fastness of the printed pattern, ensuring the durability of the functional pattern.

[0043] Excellent hand feeling: scientific post-treatment steps, especially the application of hydrophilic organic silicone softener, ensures the function of the pattern while giving the fabric excellent softness, drape, and wearing comfort.

[0044] The use of water-based ink and lower processing temperature (relative to traditional thermal curing) reduces VOC emissions, meeting the requirements of green environmental protection and sustainable development.

[0045] Process flexibility: This method is suitable for various complex digital printing pattern designs and can flexibly adjust the parameters of temperature-sensitive pigments, phase change materials, and curing processes to meet the functional and aesthetic needs of different products. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 The process flowchart of the present invention. DETAILED DESCRIPTION

[0047] REFERENCE Figure 1 Further explanation of the invention: First step, fabric pretreatment: The substrate used in this example is 100% mulberry silk fabric, which has been subjected to conventional refining and bleaching treatment to remove natural impurities and improve whiteness. Subsequently, the fabric is subjected to a composite enzyme system surface modification treatment assisted by ultrasonic waves.

[0048] Selection and ratio of composite enzyme system: The composite enzyme system contains sericinase and alkaline protease. The main role of sericinase is to gently remove sericin protein, providing a more uniform surface for subsequent dyeing; alkaline protease helps to further hydrolyze certain side chains in silk fibroin, increasing the hydrophilicity of the fiber. Commercially available sericinase and alkaline protease stock solutions are mixed in a volume ratio of 1:1, then diluted with a phosphate buffer solution to a total enzyme concentration of 0.5%–2.0% (v / v), with sodium phosphate dibasic (Na2HPO4) 0.1 M and potassium phosphate monobasic (KH2PO4) 0.1 M, adjusting the pH to 7.5-9.0. The enzyme solution is placed in a treatment tank with the silk fabric, and an ultrasonic generator with a frequency of 25-40 kHz is started in a water bath at 30–45°C to enhance the contact between the enzyme and the silk fiber and improve the efficiency of enzymatic hydrolysis, lasting for 30–60 minutes.

[0049] After the treatment, the silk fabric is thoroughly rinsed. The wettability of the fabric surface is evaluated by a water contact angle measuring instrument. This example requires that the water contact angle of the fabric surface after treatment be less than or equal to 30°, indicating that the fiber surface has been effectively modified and the hydrophilicity has been significantly enhanced, laying the foundation for uniform penetration and adhesion of subsequent ink.

[0050] Second step, preparation of functional temperature-sensitive ink: The temperature-sensitive ink prepared in this example is a multi-component functional ink with synergistic effect. The core of the temperature-sensitive pigment system is a temperature-sensitive pigment prepared by microencapsulation technology. The microcapsule shell material is preferably polyurethane to provide good wear resistance and stability. The pigment itself has a thermal hysteresis effect, i.e., there is a temperature difference (ΔT = 2-8°C) between the heating color change point (e.g., from blue to red) and the cooling recovery color change point (from red to blue). This hysteresis effect helps to achieve memory or delayed response of the temperature-sensitive pattern. The specific type and color of the pigment will be determined according to the expected pattern effect. Temperature-sensitive pigments based on liquid crystals or organic dyes can be used. The core substance of the phase change material encapsulated by microcapsules is a mixture of n-alkanes with chain lengths C18-C28. Such alkanes have a clear melting / solidification temperature and a large latent heat of fusion, requiring a latent heat of phase change greater than 150 J / g. The key is that the phase change core temperature is designed and fixed between 26°C and 34°C. When the ambient temperature fluctuates within this range, the phase change material will undergo a phase change, absorbing or releasing a large amount of latent heat of phase change, thereby stabilizing or buffering the temperature of the surrounding environment, which is crucial for regulating the color change behavior of the temperature-sensitive pigment, ensuring that the color change depends on a specific temperature range.

[0051] The inorganic nanoparticles are preferably at least one of nano-silicon dioxide (SiO2), nano-titanium dioxide (TiO2), or nano-aluminum oxide (Al2O3). These nanoparticles have a high specific surface area and strengthening effect. Before use, they are subjected to surface modification treatment with a silane coupling agent such as KH550. The functional groups of the silane coupling agent can form covalent bonds with the surface of the nanoparticles, and the other end of the functional groups can interact with the water-based adhesive or the microcapsule shell, improving the dispersibility and compatibility of the nanoparticles in the ink system, and enhancing the adhesion and weather resistance of the ink. The average particle size is controlled to be between 20 and 100 nanometers.

[0052] An aqueous acrylic or polyurethane-based adhesive is selected to provide good film-forming properties, water resistance, and adhesion to silk fibers.

[0053] The above components are mixed in proportion. First, the temperature-sensitive pigment microcapsules, modified inorganic nanoparticles, and phase change material microcapsules are dispersed in the aqueous binder, and high-shear dispersion (such as using a high-speed stirrer or sand mill) is performed to ensure uniform dispersion of the components and prevent agglomeration. Subsequently, a defoaming treatment is performed under vacuum conditions to remove bubbles in the system to prevent pinholes or discontinuous printing during the printing process.

[0054] The viscosity of the ink is determined by a rheometer, and the ink is required to have a shear rate of 100 s -1 The viscosity is then stabilized at 8-20 mPa·s, which ensures that the ink has good jetting performance in the piezoelectric printhead, neither clogging the printhead due to excessively high viscosity nor causing blurred edges or bleeding due to excessively low viscosity.

[0055] A high-resolution (not less than 600 dpi) piezoelectric digital inkjet printing machine is selected, and the temperature-sensitive ink prepared in step two is precisely applied to the designated area of the silk fabric in a layered or juxtaposed manner. Layered printing refers to superimposed printing of inks of different colors or with different functions, and juxtaposed printing refers to side-by-side printing of inks of different colors or functions. In order to form a hidden pattern that appears later, the following specific implementation is adopted:

[0056] A temperature-sensitive ink that exhibits a first effective color (such as transparent or light color) in a first temperature range (15-25°C) and changes to a second color (such as bright red) in a second temperature range (30-40°C) is used. The key is that the CIELAB color difference value ΔE between the two colors is ≥ 20, ensuring a significant visual contrast. A reference silk fabric sample is printed with the temperature-sensitive ink and completely cured, and then a spectrophotometer is used to measure the surface color value in the first temperature range (15-25°C), which is used as the basis for the design of the background pattern (target color value). Based on the measured target color value, the background ink is prepared. The background ink contains conventional colorants without temperature-sensitive color-changing function and uses the same type of aqueous aliphatic polyurethane binder as the temperature-sensitive ink; the color of the background ink needs to be highly consistent with the color of the temperature-sensitive ink in the first temperature range (target color value). By adjusting the proportion of conventional colorants, the color difference value ΔE between the cured background pattern color and the target color value is ≤ 1.5, achieving a nearly perfect visual fusion, making the hidden pattern almost invisible at lower temperatures. The prepared temperature-sensitive ink is precisely printed as a hidden pattern on the predetermined position of the silk fabric.

[0057] An intermediate curing process is applied to the printed fabric with the hidden pattern. At this stage, the fabric is heated at a temperature of 50-70°C for 2-5 minutes. This temperature and time are intended to preliminarily solidify the ink, allowing it to maintain its pattern shape in subsequent steps, but without activating the full color change function of the temperature-sensitive pigments or phase-change materials (especially the potential color change range of the phase-change materials).

[0058] A visual alignment system is used to achieve high-precision calibration, allowing the background ink to be accurately printed in the adjacent or surrounding area of the hidden pattern. To ensure the continuity and visual effect of the pattern, the edges of the background pattern need to be precisely overlapped with the edges of the hidden pattern, with an overlap of ≤ 0.1 mm. This small overlap ensures a smooth color transition when the hidden pattern appears, avoiding harsh boundaries.

[0059] Fourth step, composite energy composite curing: a two-stage step curing strategy is used, combining near-infrared (NIR) radiation and hot air convection to optimize the curing effect, especially when dealing with areas with different ink load.

[0060] First stage: after printing, the fabric is sent through a conveyor belt into a composite curing oven. The entire fabric is treated at a temperature of 60-80°C, with the application of hot air convection and near-infrared (NIR) radiation. The NIR radiation intensity is set at 5-15 kW / m², and the curing time is 10-20 minutes. The purpose of this stage is to preliminarily and uniformly pre-cure the ink layer on the entire fabric, which helps to evaporate water, preliminarily form a film of adhesive and pigments, and fix the shape of the ink. At the same time, NIR radiation can penetrate a certain thickness, accelerating the evaporation of internal moisture and early cross-linking reactions.

[0061] Second stage: duration of 20-30 minutes, identifying and processing the load differences of the ink in different areas (pattern area), achieving regional fine curing by dynamically adjusting the NIR radiation power and temperature.

[0062] Calculate ink load: before curing, the theoretical ink application volume (ink load) of each area of the pattern is obtained through the graphic data input of the printing machine. This can be estimated by calculating the number of ink dots or models in a unit area. The system can read the ink load value of each area and match the corresponding second-stage curing parameters accordingly.

[0063] High ink load area: these areas have thicker ink, which requires more energy and longer time for full curing. Therefore, they are matched with high near-infrared radiation power (corresponding to higher NIR lamp voltage or power output) and higher temperature (125-130°C).

[0064] Low ink load area: These areas have thinner ink, and too much energy will cause over-curing or damage to the substrate, so lower near-infrared radiation power and lower temperature (110-115°C) are matched for them. At this stage, the hot air flow rate is kept at 0.2-0.5 m / s to ensure uniform heat transfer and effective removal of volatile substances.

[0065] NRI radiation mainly provides penetrating heating, which can quickly raise the temperature inside the ink layer, accelerate the polymerization reaction of the adhesive (such as the aqueous curing of polyurethane), and activate the phase change process of the phase change material. Hot air convection helps to evaporate surface moisture and works synergistically with NIR radiation to ensure uniformity of temperature distribution. Through this regional temperature and radiation power control, incomplete curing of high ink load areas can be avoided, while preventing material degradation or discoloration in low ink load areas due to overheating.

[0066] Fifth step, finishing: After the fabric is completely cured, the following wet finishing treatment is carried out to further improve the performance and wearing comfort of the functional printed fabric.

[0067] Soaping treatment: To remove possible residual unreacted substances, a small amount of loose pigment particles or auxiliaries on the surface of the fabric. A non-ionic soaping agent with a concentration of 1-3 g / L is used. Non-ionic soaping agents are mild and do not easily damage dyes and treatments, and are carried out at 40-50°C for 10-15 minutes.

[0068] After soaping, the fabric is thoroughly rinsed with clean water to completely remove the soaping agent and dirt.

[0069] Soft finishing treatment improves the hand feel of the fabric, increasing the softness and drape of the fabric.

[0070] Softener: Hydrophilic silicone or modified amino silicone oil softener is selected. This type of softener can form a thin film on the fiber surface, giving the fabric excellent softness and good hydrophilicity, avoiding the staining problem that may be caused by traditional softeners. The concentration is 10-30 g / L, and the temperature is 30-40°C, and the treatment time is 15-20 minutes. The final goal of the finishing treatment is to control the pH value of the finished fabric product in the weakly acidic or neutral range of 6.0-7.5. This helps to protect silk fibers from damage and provides a more comfortable environment for wearing.

[0071] To verify the effectiveness of the invention, we will set up the following examples and comparative examples and conduct a series of performance tests.

[0072] Example 1:

[0073] Fabric pretreatment: according to the above method, the silk fabric (dtex = 16-20, density = 220 needles / inch) is treated in a phosphate buffer at 35°C, pH 8.0, with a total concentration of 1.0% (v / v) of sericinase and alcalase, ultrasound 30 kHz, for 45 minutes. The water contact angle is reduced to 25°. Functional thermo-sensitive ink preparation:

[0074] Thermo-sensitive pigment: microencapsulated polyurethane shell, blue (20°C) <-> red (30°C), ΔΤ = 5°C, ΔE (blue-red) = 25; phase change material: C20-C26 alkane mixture, latent heat of phase change 180 J / g, core temperature 30°C; inorganic nanoparticles: nanosilica modified with silane coupling agent (d50 = 50 nm); water-based binder: polyurethane dispersion; ink viscosity (100 s -1 ): 12 mPa-s.

[0075] High-precision digital printing:

[0076] Thermo-sensitive ink: a hidden pattern (e.g. a butterfly) is printed on the silk fabric; intermediate curing at 60°C for 3 minutes; using a spectrophotometer, the target colorimetry in the first temperature interval (15-25°C) is L = 90, a = -2, b = 5 (close to white); the background ink is formulated with a conventional colorless transparent colorant and the same polyurethane binder, after curing the color difference ΔE is ≤ 1.0; background pattern printing: the background pattern surrounds the butterfly, with an overlap ≤ 0.05 mm.

[0077] Composite energy curing:

[0078] First stage: 70°C, NIR 10 kW / m2, hot air, 15 minutes.

[0079] Second stage: high ink load butterfly area: 128°C, NIR 15 kW / m2, hot air 0.3 m / s, 25 minutes; low ink load background area: 113°C, NIR 8 kW / m2, hot air 0.3 m / s, 25 minutes.

[0080] Finishing: soaping agent 2 g / L, 45°C, 12 minutes; softener 20 g / L, 35°C, 18 minutes, pH 6.8.

[0081] Example 2: fabric pretreatment as in example 1.

[0082] Functional thermo-sensitive ink preparation:

[0083] Thermochromic ink: thermochromic pigment with microencapsulated polyurethane shell, red (25°C) <-> yellow (35°C), ΔΤ = 8°C, ΔE (red-yellow) = 28; phase change material: mixture of C18-C28 alkanes, latent heat of phase change 160 J / g, core temperature 33°C; inorganic nanoparticles: nanoscale titanium dioxide modified with silane coupling agent (d50= 80 nm); waterborne binder: acrylate dispersion; ink viscosity (100 s -1 ): 18 mPa-s.

[0084] High-precision digital printing:

[0085] Thermochromic ink: hidden pattern printed at random locations on the silk fabric; intermediate curing: 70°C, 5 minutes; target colorimetry for the first temperature interval (15-25°C) L = 88, a = 5, b = 10 (pale yellow); background ink: conventional yellow dye formulated with the same acrylate binder, color difference ΔE < 1.2 after curing; background pattern: background pattern printed interleaved with the hidden pattern, overlap < 0.1 mm.

[0086] Composite energy curing: first stage: 65°C, NIR 8 kW / m2, hot air, 12 minutes.

[0087] Second stage: high ink load pattern area: 130°C, NIR 13 kW / m2, hot air 0.4 m / s, 30 minutes; low ink load background area (no pattern): 110°C, NIR 6 kW / m2, hot air 0.4 m / s, 30 minutes.

[0088] Finishing: soaping agent 3 g / L, 50°C, 15 minutes; softener 15 g / L, 40°C, 20 minutes, pH 7.2.

[0089] Example 3: fabric pretreatment as in Example 1.

[0090] Functional thermochromic ink preparation:

[0091] Thermochromic ink: thermochromic pigment with microencapsulated polyurethane shell, green (22°C) <-> blue (28°C), ΔΤ = 4°C, ΔE (green-blue) = 22; phase change material: mixture of C22-C28 alkanes, latent heat of phase change 170 J / g, core temperature 28°C; inorganic nanoparticles: nanoscale alumina modified with silane coupling agent (d50= 30 nm); waterborne binder: polyurethane dispersion; ink viscosity (100 s -1 ): 10 mPa-s.

[0092] High-precision digital printing:

[0093] Thermally sensitive ink printed on silk fabric with a hidden pattern; intermediate curing: 50°C, 2 minutes; first temperature interval (15-25°C) target colorimetry L=92, a=-5, b=5 (close to white); background ink formulated with the same polyurethane binder and conventional colorless transparent colorants, color difference ΔE < 1.5 after curing; background pattern fills most of the fabric area, hidden pattern is located within it, overlap < 0.08 mm.

[0094] Composite energy curing: first stage: 60°C, NIR 5kW / m2, hot air, 10 minutes;

[0095] Second stage: high ink amount pattern area: 125°C, NIR 10kW / m2, hot air 0.2m / s, 20 minutes; low ink amount background area: 115°C, NIR 5kW / m2, hot air 0.2m / s, 20 minutes.

[0096] Finishing: soaping agent 1g / L, 40°C, 10 minutes; softener 10g / L, 30°C, 15 minutes, pH 6.2.

[0097] Comparative Example 1: without ultrasonic assistance

[0098] Fabric pretreatment: same enzyme system and ratio, but in phosphate buffer at 35°C, pH 8.0, without ultrasonic assistance, 45 minutes; S2-S5: same process and materials as in Example 1.

[0099] Comparative Example 2: single energy curing (hot air only)

[0100] S1-S3: same process and materials as in Example 1.

[0101] Composite energy curing with hot air convection only (e.g. 125°C, 0.3m / s, 30 minutes), without NIR radiation.

[0102] Finishing: same process as in Example 1.

[0103] Comparative Example 3: without phase change material

[0104] S1-S2: in S2, the phase change material is not added, other components and processes are the same.

[0105] S3-S5: same process and materials as in Example 1.

[0106] Comparative Example 4: without nanoparticles

[0107] S1-S2: in S2, the inorganic nanoparticles are not added, other components and processes are the same.

[0108] S3-S5: Same process and materials as in Example 1 were used.

[0109] Performance Test Methods

[0110] Water Contact Angle: Using a contact angle meter, the angle of a water droplet on the fabric surface after spreading for 2 seconds was recorded.

[0111] Color Change Performance Test:

[0112] Color Change Temperature Measurement: In a thermostat, using a temperature control console and a spectrophotometer, the temperature at which the pattern on the fabric changes from one color to another (both heating and cooling) was recorded at a rate of 1°C / min.

[0113] Color Difference Value (ΔE): Using a spectrophotometer, the colorimetric values of the pattern were measured at the first and second temperature intervals, and the CIELAB color difference was calculated.

[0114] Thermal Hysteresis Effect: The temperature difference between the heating color change point and the cooling color change recovery point was recorded.

[0115] Concealment Evaluation: In the first temperature interval, the degree of integration of the hidden pattern with the background pattern was visually inspected. The color difference (ΔE) between the hidden pattern area and the background area was measured using a spectrophotometer, with a requirement of ≤1.5.

[0116] Washing Fastness: According to the GB / T 3921 (Color Fastness to Washing of Fabrics) standard, the color brightness, clarity, and contrast with the background of the color-changing pattern after multiple washes were evaluated.

[0117] Rubbing Fastness: According to the GB / T 3920 (Color Fastness to Rubbing of Fabrics) standard, the staining of the pattern after dry and wet rubbing was evaluated.

[0118] Adhesion Test: Using a pressure-sensitive tape method (such as ASTM D3359), the adhesion of the printed layer on the fabric was evaluated.

[0119] Hand Feel and Wear Comfort: Through expert review or sensory evaluation, the softness, drape, and overall comfort of the fabric were evaluated.

[0120] Curing Uniformity: The integrity of the pattern after curing was observed, and whether there were white spots, transfer, or peeling phenomena caused by uneven curing was observed.

[0121] The above test results are as follows in Table 1:

[0122]

[0123] Data Analysis:

[0124] Ultrasonic-assisted treatment (Comparative Example 1 vs. Example 1): The water contact angle of Comparative Example 1 is significantly higher than that of Example 1, indicating that the lack of ultrasonic assistance leads to poor enzyme treatment effect, and the hydrophilicity of the fiber surface is insufficient. This directly affects the subsequent ink penetration and adhesion. Comparative Example 1 also shows a decrease in wash fastness and adhesion.

[0125] Composite energy curing (Comparative Example 2 vs. Example 1): Comparative Example 2 uses single hot air curing, and in Comparative Example 2, the curing effect of high ink amount areas (such as the butterfly pattern of Example 1) is significantly inferior to that of Example 1, showing color under-saturation and possibly hardened areas of the pattern. The composite energy curing of Example 1, especially the gradient control of the second stage, ensures that different ink amount areas can achieve the best curing effect. The introduction of NIR radiation accelerates internal curing, improving overall fastness and hand feel.

[0126] Role of phase change material (Comparative Example 3 vs. Example 1): Comparative Example 3 does not add phase change material. The results show that Example 1 is superior to Comparative Example 3 in terms of stability at color change temperature and thermal hysteresis effect. The presence of phase change material helps to alleviate the impact of temperature fluctuations on the color change process and provides more obvious and controllable thermal hysteresis, which is the key to achieving "pattern memory" and "temperature buffering".

[0127] Role of nanoparticles (Comparative Example 4 vs. Example 1): Comparative Example 4 does not add nanoparticles. The results show that the presence of nanoparticles (especially after surface modification) significantly improves the adhesion, rubbing fastness and washing fastness of the ink. At the same time, nanoparticles may also have a positive impact on the rheological properties of the ink, the dispersion stability of pigments and the film-forming properties after curing, reflected in hand feel and curing uniformity.

[0128] Conclusion:

[0129] The above comparative experimental data show that each step and key component of the invention plays a unique role.

[0130] The ultrasonic-assisted enzyme treatment of S1 is the basis for achieving excellent hydrophilicity of the fabric.

[0131] The functional ink of S2, especially the synergistic effect of temperature-sensitive pigments (containing thermal hysteresis), phase change materials and modified nanoparticles, is the carrier for achieving intelligent color change and improving comprehensive performance.

[0132] The hidden pattern design of S3 is the key to achieving visual surprise, and the color difference control between the background color and the temperature-sensitive pattern at low temperature is crucial.

[0133] The composite energy curing of S4, especially the gradient curing in the second stage, is the key technology to ensure sufficient curing in different ink amount areas and optimize processing efficiency and product quality.

[0134] The wet finishing of S5 has a decisive influence on the hand feeling and the quality of the final product.

[0135] Further analysis of the preferred range of raw material ratio / structure parameter:

[0136] Enzyme concentration (0.5%-2.0% v / v): Lower concentration (such as 0.5%) is suitable for short time or mild modification, with lower energy consumption; higher concentration (such as 2.0%) can quickly reach the target contact angle, but the cost is higher, and it may be over-processed. The preferred range is 1.0%-1.5%, which can achieve a good balance between cost and efficiency.

[0137] Phase change material core temperature (26℃-34℃): This range covers the main comfortable temperature area of human body perception of warming. The preferred range is 28℃-30℃, which can achieve cool in summer and warm in winter touch.

[0138] Thermal hysteresis of temperature-sensitive pigment (2℃-8℃): Smaller hysteresis (2℃) responds quickly; larger hysteresis (8℃) has a more lasting effect. The preferred range is 4℃-6℃, which can provide observable hysteresis effect while ensuring certain response speed.

[0139] Average particle size of inorganic nanoparticles (20-100nm): Smaller particle size (20-40nm) has better dispersion, but higher cost; larger particle size (80-100nm) may affect dispersion uniformity. The preferred range is 40-60nm, which balances dispersion and cost.

[0140] NIR radiation intensity (5-15kW / m²): The higher the NIR intensity, the faster the heating, but more precise control is needed to prevent local overheating. The preferred range is 8-12kW / m², which can achieve efficient drying and curing.

[0141] Temperature control (110-130℃): This temperature range is the preferred curing range for waterborne polyurethane systems. The preferred range is 115-125℃, which can obtain high-performance cured layers.

[0142] The above only describes the preferred embodiments of the present application and does not limit the present application. Those skilled in the art can make usual changes and replacements within the technical solution range of the present application, which should be included in the protection scope of the present application.

Claims

1. An intelligent printing and dyeing method for thermosensitive color-changing silk fabric, characterized in that, Includes the following steps: S1. Fabric pretreatment: The mulberry silk fabric is conventionally refined and bleached, and then subjected to ultrasonic-assisted composite enzyme surface modification treatment until the water contact angle of the fabric surface is less than or equal to 30°. S2. Preparation of Functionalized Thermosensitive Ink: A component comprising a thermosensitive pigment system, microencapsulated phase change material, inorganic nanoparticles, and an aqueous binder is prepared by high-shear dispersion and vacuum degassing to create a thermosensitive ink that operates at a shear rate of 100 s⁻¹. -1 Inks with a viscosity of 8-20 mPa·s; S3. High-precision digital printing: Using piezoelectric digital printing equipment, the ink prepared in step S2 is applied to the designated area of ​​the silk fabric in layers or side by side at a resolution of not less than 600 dpi. S4. Composite Energy Curing: The dyed fabric undergoes a two-stage stepped curing process, using a combination of near-infrared radiation and hot air convection as the curing energy source. S5. Finishing: The cured fabric is subjected to a wet finishing process that includes soaping, rinsing and softening steps.

2. The intelligent printing and dyeing method for thermosensitive color-changing silk fabric according to claim 1, characterized in that, The surface modification treatment of the complex enzyme system in step S1 is carried out in a phosphate buffer solution. The complex enzyme system contains sericinase and alkaline protease, with a total concentration of 0.5%–2.0% (v / v). The treatment temperature is 30–45℃, the pH value is 7.5–9.0, and it is supplemented by ultrasound at 25–40 kHz for 30–60 minutes.

3. The intelligent printing and dyeing method for thermosensitive color-changing silk fabric according to claim 1, characterized in that, The thermosensitive pigment described in step S2 is encapsulated in microcapsules. The wall material of the microcapsules is polyurethane, and the pigment system contains pigments with thermal hysteresis effect, with a temperature difference of 2°C to 8°C between the color change point when heated and the color recovery point when cooled.

4. The intelligent printing and dyeing method for thermosensitive color-changing silk fabric according to claim 1, characterized in that, The inorganic nanoparticles mentioned in step S2 are selected from at least one of nano-silica, nano-titanium dioxide or nano-alumina, with an average particle size of 20-100 nanometers, and are surface modified by a silane coupling agent before use.

5. The intelligent printing and dyeing method for thermosensitive color-changing silk fabric according to claim 1, characterized in that, The phase change material encapsulated in the microcapsules described in step S2 has a core material that is a mixture of n-alkanes with chain lengths of C18-C28, a latent heat of phase change greater than 150 J / g, and a phase change core temperature set between 26℃ and 34℃.

6. The intelligent printing and dyeing method for thermosensitive color-changing silk fabric according to claim 1, characterized in that, The high-precision digital printing and dyeing in step S3, which forms a hidden and then revealed pattern on the fabric, specifically includes the following steps performed in sequence: First, take the ink prepared in step S2. The ink has the following characteristics: it presents a first effective color in a first temperature range, and changes to a second color in a second temperature range, and the CIELAB color difference value ΔE between the first and second effective colors is ≥20. After the ink is printed on a reference silk fabric sample and completely cured, its surface colorimetric value is measured using a spectrophotometer within the first temperature range as the target colorimetric value. Based on the measured target chromaticity value, a background ink containing a conventional non-color-changing colorant and the same water-based aliphatic polyurethane binder as the temperature-sensitive ink is prepared. The color difference between the cured background ink and the target chromaticity is ΔE≤1.

5. Reversible thermosensitive ink is used to print hidden patterns on predetermined locations on silk fabric; Fabrics with hidden patterns are subjected to intermediate curing treatment at a temperature of 50-70℃ for 2-5 minutes. A visual alignment system is used to print background ink in the area adjacent to or surrounding the hidden pattern, ensuring that the edges of the background pattern and the edges of the hidden pattern overlap by ≤0.1mm.

7. The intelligent printing and dyeing method for thermosensitive color-changing silk fabric according to claim 1, characterized in that, The two-stage stepped curing process in step S4 includes the following steps: The first stage involves uniformly pre-curing the entire fabric at a temperature of 60–80°C using a combination of hot air and near-infrared (NIR) radiation with an intensity set at 5–15 kW / m², for a time of 10–20 minutes. The second phase lasts 20-30 minutes and is carried out in the following steps: Calculate ink load: Before curing, acquire the pattern data from step S3 and calculate the theoretical ink application volume for each region of the pattern; Matching process parameters: Based on the calculated ink load value, independent second-stage curing parameters are matched for each area of ​​the pattern. Specifically, high near-infrared radiation power and temperature are matched for areas with high ink load, with a temperature of 125-130℃, while low near-infrared radiation power and temperature are matched for areas with low ink load, with a temperature of 110-115℃. At the same time, the hot air flow rate is controlled at 0.2-0.5m / s.

8. The intelligent printing and dyeing method for thermosensitive color-changing silk fabric according to claim 1, characterized in that, The specific process conditions for the wet finishing treatment in step S5 are as follows: Soap washing treatment: Use a nonionic soap washing agent with a concentration of 1-3g / L and treat at 40-50℃ for 10-15 minutes; Softening treatment: Use a hydrophilic organosilicon or modified amino silicone oil softener with a concentration of 10-30g / L, treat at 30-40℃ for 15-20 minutes, and finally control the pH value of the finished fabric to 6.0-7.

5.

9. A thermosensitive color-changing silk fabric, characterized in that, It is produced by an intelligent printing and dyeing method for a thermosensitive color-changing silk fabric as described in any one of claims 1-8, wherein the fabric has a functional pattern layer. The functional patterned layer includes a hidden patterned area and a background patterned area; the hidden patterned area contains the first microcapsule component; the background patterned area contains a conventional non-color-changing colorant, and its color differs from the color of the first microcapsule component by ΔE ≤ 1.5 in a first temperature range.

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