Multilayer thermochromic coating, fabric and preparation method of fabric

Abstract

The invention provides a multi-layer thermochromic coating, a fabric and a preparation method of the fabric, and belongs to the technical field of thermosensitive coatings. The coating is formed by mixing water-soluble polyurethane and four thermochromic microcapsule powder with different temperature ranges, and the coating is endowed with four layers of thermochromism. Uniformly coating the surface of the fabric with the prepared coating, and controlling the using amount of the coating through a scraper to ensure the thickness of the coating; the multi-layer thermochromic fabric is characterized in that the fabric is coated with thermochromic paint, then the fabric coated with the thermochromic paint is placed in a drying oven, drying treatment is conducted at the set temperature, and the multi-layer thermochromic fabric is obtained. Meanwhile, the fabric has the properties of air permeability, good hand feeling, breaking strength, washing resistance, wear resistance, solarization resistance, dry and wet friction resistance and the like, is suitable for the fields of textile, clothing, military industry and the like, and has a wide application prospect.

Description

Technical Field

[0001] The present application relates to a multi-layered thermochromic coating, a fabric and a method for preparing the fabric, and belongs to the technical field of thermosensitive coatings. Background Art

[0002] As the traditional textile industry matures, research has gradually shifted to multifunctionality and intelligence. By combining smart materials, fabrics have the ability to sense and respond to external stimuli, such as color change, temperature regulation, and antibacterial, expanding functionality and increasing added value. As a type of smart material, color-changing fabrics have shown great potential in the fields of anti-counterfeiting, smart homes, and thermal storage. They can change color according to changes in temperature, light, humidity, or pressure, and have reminder, warning, or anti-counterfeiting functions.

[0003] At present, it is a common process to prepare a color-changing coating on the surface of a fabric by a single-layer coating method. For example, CN118273094A discloses a method for changing the color of a fabric, which realizes the intelligent color-changing function of the fabric under various stimuli by coating the fabric with a material that responds to electrical, optical, and thermal stimuli. CN111155220A discloses an intelligent color-changing curtain and its control system, which realizes the color change of the curtain by weaving silver-plated conductive nylon filaments into the inner layer of the curtain and applying thermochromic ink on the surface layer, which is then heated by electricity and conducted to the surface layer to activate the thermochromic ink on the surface layer. CN101817251A applies color-changing ink on the surface of the fiber line of the fabric, so that the fabric changes color according to environmental conditions.

[0004] Although the thermochromic fabrics prepared by the above scheme have good color change response and reversible performance, the single-layer coating method has obvious limitations. Its color change level is single, and it can only achieve simple color changes (such as black-colorless, red-colorless) within a specific temperature range, and the color change temperature is fixed (such as 38℃ black-colorless, 38℃ red-colorless), which limits its application in smart home, outdoor protection and high-end fashion scenes that require more complex color changes. Summary of the invention

[0005] In view of this, the present application first provides a multi-layered thermochromic coating, which not only gives the coating multi-layered thermochromic properties, but also has strong bonding strength with the fabric and is not easy to fall off.

[0006] Specifically, the present application is implemented through the following scheme:

[0007] A multi-level thermochromic coating is prepared by mixing water-soluble polyurethane with four thermochromic microcapsule powders in different temperature ranges, which gives the coating four levels of thermochromic properties.

[0008] Further, as a preference:

[0009] The color changing temperature range of the thermochromic microcapsule powder is 31-40° C. More preferably, the thermochromic microcapsule powder includes 31° C. thermochromic microcapsule powder, 35° C. thermochromic microcapsule powder, 38° C. thermochromic microcapsule powder, and 40° C. thermochromic microcapsule powder, with a mass ratio of 1-2:0.5-1:0.5-1:0.5-1.5, giving the coating a multi-level color changing property of yellow, orange, red, and purple with temperature changes.

[0010] The addition amount of the thermochromic microcapsule powder is 1-4% of the mass of the water-soluble polyurethane.

[0011] As a preferred case: in the multi-layer thermochromic coating, the addition amount of the thermochromic microcapsule powder is 2% of the mass of the water-soluble polyurethane, and it is mixed with 31°C thermochromic microcapsule powder, 35°C thermochromic microcapsule powder, 38°C thermochromic microcapsule powder, and 40°C thermochromic microcapsule powder in a mass ratio of 2:1:1:1.

[0012] The second purpose of the applicant is to provide a method for preparing a multi-layered thermochromic fabric, which comprises selecting four thermochromic microcapsule powders in different temperature ranges, adding them to water-soluble polyurethane, stirring and fully blending them to obtain a multi-layered thermochromic coating; applying the multi-layered thermochromic coating on the surface of the fabric, and drying it to obtain a multi-layered thermochromic fabric.

[0013] in:

[0014] The stirring time for full integration is ≥7 minutes.

[0015] The coating thickness is greater than 0.15 mm, preferably 0.2 mm.

[0016] The drying temperature is 65-95°C, the drying time is 10-50 minutes, and it is best to dry at 70°C for 45 minutes.

[0017] In the above preparation method, based on reversible thermochromic powders at four different temperatures, the coating ratio and process are combined with a multi-layered thermochromic coating to make each color-changing powder evenly distributed on the fabric surface, thereby improving the color change level of the fabric, thereby achieving a variety of color changes in the fabric at different temperatures, and enhancing its durability and wide application.

[0018] The third purpose of the applicant is to provide a multi-layered thermochromic fabric, including a coating layer and a fabric, wherein the coating layer is obtained by applying a multi-layered thermochromic coating on the surface of the fabric and drying it, and the multi-layered thermochromic coating includes a water-soluble polyurethane and four thermochromic microcapsule powders in different temperature ranges, giving the multi-layered thermochromic fabric four levels of thermochromism, and its color change temperature range is 31 to 40°C.

[0019] The beneficial effects of the present invention are:

[0020] (1) Rich multi-level color change effect: The present invention uses four different temperature ranges of thermochromic microcapsule powders to enable the fabric to display multi-level color changes under various temperature conditions. Compared with the fixed color conversion of the traditional single-layer coating method, the present invention can show a variety of changes in yellow, orange, red, and purple at 31°C, 35°C, 38°C, and 40°C, respectively. This diverse color change effect significantly improves the functionality and aesthetics of the product, and broadens the scope of application in smart home, outdoor protection, and high-end fashion.

[0021] (2) Enhanced durability and color change performance: By optimizing the ratio of thermochromic microcapsule powder and water-soluble polyurethane, the multi-layered thermochromic fabric prepared by the present invention has excellent color fastness and wear resistance. At a coating thickness of 0.2 mm, a drying time of 45 minutes and a drying temperature of 70°C, the color change response speed of the fabric is fast and the color change is significant, which can meet the durability requirements in actual use.

[0022] (3) Stable coating adhesion: The present invention uses water-soluble polyurethane as the coating matrix, which effectively improves the adhesion and uniformity of the coating on the fabric surface. The test by scanning electron microscope shows that the thermochromic powder is evenly distributed after coating, and the chemical composition of the developer is not damaged, thus ensuring the stable color change performance of the fabric after multiple uses and washings.

[0023] This application successfully solves the problems of single color change, complex coating structure and poor durability in traditional methods by optimizing the preparation and coating process of thermochromic coatings, and achieves excellent color performance and temperature response characteristics. At the same time, it has air permeability, good hand feel, breaking strength, and resistance to water washing, wear, sunlight, dry and wet friction, etc. It is suitable for the fields of textiles, clothing, military industry, etc., and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a schematic diagram of the structure of the multi-layered thermochromic fabric of this application.

[0026] Numbers in the figure: 1. fabric; 2. thermochromic coating;

[0027] Figure 2 is a SEM photo of the thermochromic microcapsule powder in Example 1,

[0028] (a) is the SEM photo of the thermochromic microcapsule powder at 31°C.

[0029] (b) is the SEM photo of the thermochromic microcapsule powder at 35°C.

[0030] (c) is the SEM photo of the thermochromic microcapsule powder at 38°C.

[0031] (d) is the SEM image of the thermochromic microcapsule powder at 40°C;

[0032] Figure 3 This is a SEM photo of the multi-layered thermochromic fabric obtained in Example 1.

[0033] (a) is a SEM image of the multi-layered thermochromic fabric before coating with thermochromic coating.

[0034] (b) is the SEM image of the multi-layered thermochromic fabric after coating with thermochromic coating;

[0035] Figure 4 This is a reflection spectrum of the visible light band of the multi-layered thermochromic fabric obtained in Example 1;

[0036] Figure 5 The visible light reflection spectrum of the fabric obtained in Comparative Example 1 before and after color change;

[0037] Figure 6 This is a reflection spectrum of the fabric obtained in Comparative Example 2 in the visible light band;

[0038] Figure 7 This is the visible light reflection spectrum of the fabric obtained in Comparative Example 3. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application clearer, the technical solutions in the embodiments of this application will be further described in detail in conjunction with the drawings in the embodiments of this application. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit the technical solutions of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0040] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments. The raw materials used in the present invention are all commercially available unless otherwise specified.

[0041] The microscopic morphology of fabrics and coating materials was observed by FE-SEM (ULTRA 55) scanning electron microscope, and the color of powders and multi-layered thermochromic fabrics made of different proportions during different temperature changes was tested by data color 600X to obtain the visible light band reflectance spectra under different conditions.

[0042] Example 1

[0043] The preparation method of the multi-layered thermochromic fabric of this embodiment is as follows:

[0044] Step 1: Preparation of multi-layer thermochromic coating:

[0045] Weigh 10 grams of water-soluble polyurethane into a clean beaker.

[0046] Weigh 2g of capsule powder in the ratio of 2:1:1:1, including: 0.8g of 31℃ thermochromic capsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.), 0.4g of 35℃ thermochromic capsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.), 0.4g of 38℃ thermochromic capsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.), and 0.4g of 40℃ thermochromic capsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.).

[0047] The capsule powder is added to the water-soluble polyurethane, and stirred at a speed of 500 rpm using a magnetic stirrer for a stirring time of 7 minutes or more to ensure uniform mixing. The result is a multi-layered thermochromic coating.

[0048] Step 2: Apply thermochromic paint: Spread the prepared fabric flat on the workbench, and use a scraper to evenly move from one end of the fabric to the other end to apply the thermochromic paint prepared in step S1 on the fabric, and ensure that the thickness of the coating is 0.2 mm.

[0049] Step 3: Drying: Place the coated fabric in an oven preheated to 70°C for 45 minutes of drying. After drying, cool the fabric to room temperature to obtain a multi-layered thermochromic fabric.

[0050] The multi-layered thermochromic fabric structure obtained by the above method is as follows: Figure 1 As shown: a multi-layered thermochromic coating forms a thermochromic coating 2 on the surface of a fabric 1. The fabric can show yellow, orange, red, and purple at 31°C, 35°C, 38°C, and 40°C, respectively, forming a multi-layered thermochromic coating.

[0051] The SEM photo of the thermochromic microcapsule powder in step 1 is as follows: Figure 2As shown: the powders of the four thermochromic capsule powders are all similar to large beads, distributed in continuous spherical stacks. The surface of a single sphere is smooth and there are a small amount of dust-like particles scattered on it. Some spherical particles are concave and have uneven surfaces, similar to rough pearls. The diameter is 1 to 6 μm, and the size of the materials varies.

[0052] Figure 3 The SEM photos of the obtained multi-layered thermochromic fabrics are shown in Figure 1. (a) is the SEM photo of the fabric before coating. The fibers on the surface of the fiber bundle are clearly visible, the surface is smooth and in bundles, and there are almost no impurities. The diameter of a single fiber is about 5 to 7 μm, and the fiber thickness is relatively uniform. (b) is the SEM photo of the fabric after coating. In the electron microscope image under the scanning electron microscope, it can be seen that the slurry on the fiber surface contains fine particles of thermochromic capsule powder. These powder particles are well dissolved before coating and evenly mixed with the polyurethane solution. After coating, drying and other steps, they are still distributed in the shape of grape clusters on the fiber surface. It can be seen that the thermochromic coating is well added to the fabric through the coating process, and the chemical composition and chemical structure are not damaged, ensuring the stability of the thermochromic performance.

[0053] Figure 4 The visible light band reflectance spectrum curves of the multi-layered thermochromic fabric under different temperatures (31°C, 35°C, 38°C, 40°C) as stimulation conditions are shown. By comparison, it can be observed that the reflectivity of the multi-layered thermochromic fabric of this embodiment changes significantly in the wavelength range of 450nm to 700nm. Among them, the optical modulation ranges from 31°C to 40°C are 65.62%, 68.57%, 48.90%, and 65.62%, respectively, indicating that the optical response of the multi-layered thermochromic fabric at different wavelengths changes with time and has good modulation ability.

[0054] The performance test is shown in Table 1.

[0055] Table 1 Wearing performance test of the fabric obtained in Example 1

[0056] performance Test method / standard Test Results evaluate Color fastness to washing GB / T 3921-2008 4～5 excellent Color fastness to perspiration GB / T 3922-2008 4～5 excellent Wear resistance GB / T 13775-1992 Dry massage 4~5, wet massage 4 very good Breathability GB / T5453-1997 250~272mm / s good Thermal insulation (K value) GB / T 11048-1989 30.20％ Good thermal insulation Breaking strength GB / T 3923.1-1997 Warp: 1110.7N, Weft: 744N Strong and durable Elongation at break GB / T 3923.1-1997 Warp: 54.73mm, Weft: 40.35mm Good flexibility

[0057] It can be seen from Table 1 that the thermochromic fabric provided in this embodiment has good air permeability, good hand feel, breaking strength, and resistance to washing, abrasion, sunlight, dry and wet friction, and is suitable for the fields of textiles, clothing, and military industry.

[0058] Comparative Example 1

[0059] The configuration of this comparative example is the same as that of Example 1, except that in step 1, the capsule powder only includes 2 g of 38° C. thermochromic microcapsule powder (red turns to orange).

[0060] The obtained fabric was tested for visible light reflection spectrum curve under external stimulation conditions. The results are as follows: Figure 5 As shown. By comparing the spectral curves before and after the color change, we can observe that the reflectivity of the fabric obtained in this case has changed significantly in the wavelength range of 450nm to 700nm. However, compared with Example 1, its color change level is single, and it can only achieve a simple color change (red to orange) within a specific temperature range, and the color change temperature is fixed at 38°C. At this time, the color of the fabric changes from red to orange, which limits its application range.

[0061] Comparative Example 2

[0062] This comparative example has the same configuration as that of Example 1, except that: in step one, the ratio of thermochromic powder is 1:1:1:1, 31°C thermochromic microcapsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.), 35°C thermochromic microcapsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.), 38°C thermochromic microcapsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.), and 40°C thermochromic microcapsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.) are each 0.5g, with a total weight of 2g.

[0063] The obtained fabric was tested for visible light reflection spectrum curve under external stimulation conditions. The results are as follows: Figure 6 As shown: Compared with Example 1, the fabric obtained in Comparative Example 2 has a smaller optical modulation range under external stimulation, a weaker reflectivity change, and exhibits a poorer color change effect.

[0064] Comparative Example 3

[0065] The configuration of this comparative example is the same as that of Example 1, except that: in step one, the ratio of thermochromic powder is 3:2:2:3, 31°C thermochromic microcapsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.) 0.6g, 35°C thermochromic microcapsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.) 0.4g, 38°C thermochromic microcapsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.) 0.4g, 40°C thermochromic microcapsule powder (Shenzhen Huancai Color Change Technology Co., Ltd.) 0.6g, and the total weight of the microcapsule powder is 2g.

[0066] The obtained fabric was tested for visible light reflection spectrum curve under external stimulation conditions. The results are as follows: Figure 7 As shown: compared with Example 1, the fabric obtained in Comparative Example 3 has a smaller optical modulation range under external stimulation, a weaker change in reflectivity, and exhibits a poorer color change effect.

[0067] Comparative Example 4

[0068] The configuration of this comparative example is the same as that of Example 1, except that in step 1, the stirring time is 5 min.

[0069] Compared with Example 1, the color change of the fabric obtained in Comparative Example 4 is relatively weak, because the extension of the stirring time can promote the uniform mixing of the coating slurry. During the stirring process, as time goes by, more particles and substances are effectively dispersed into the slurry, making the distribution of the thermochromic microcapsule powder, a color-changing color-developing additive, in the water-soluble polyurethane material more uniform. This uniform distribution not only improves its stability, but also accelerates the efficiency of the reaction between the thermochromic microcapsule powder and the water-soluble polyurethane, thereby enhancing the bonding strength between the two.

[0070] Comparative Example 5

[0071] The configuration of this comparative example is the same as that of Example 1, except that in step 2, the coating thickness is 0.15 mm.

[0072] Compared with Example 1, the thinner coating resulted in a less uniform distribution of the thermochromic microcapsule powder in the coating, which in turn affected the overall color change effect. Due to the thinner coating thickness, the reaction rate of the thermochromic microcapsule powder when the temperature changes is relatively slow, the color change effect is relatively simple, and the layering is not strong. At the same time, the thin coating also reduces the bonding strength between the developer and the water-soluble polyurethane material, affecting the durability and color stability of the coating.

[0073] It can be seen from the above Example 1 and the comparative examples that the multi-layered thermochromic coating designed in the present application exhibits excellent performance in many aspects, especially in terms of thermochromic sensitivity, color hierarchy and stability, which is superior to the traditional method. In contrast, due to the different stirring time, proportion of thermochromic microcapsule powder and coating thickness in the comparative example, the color change effect is relatively simple, the color change is not obvious, and the stability is insufficient. In particular, when the coating is thin or the stirring is insufficient, the uniformity and bonding strength of the coating are greatly reduced, which affects the continuity and effect of the color change.

[0074] The above-mentioned embodiments only express several feasible implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention, and the embodiments are not used to limit the scope of protection in the claims of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and all equivalent implementations or changes that do not depart from the present invention should be included in the technology of the present invention.

Claims

1. A multi-layered thermochromic coating, characterized in that: It is a mixture of water-soluble polyurethane and four thermochromic microcapsule powders with different temperature ranges, giving the coating four levels of thermochromism.

2. A multi-layered thermochromic coating according to claim 1, characterized in that: The color changing temperature range of the thermochromic microcapsule powder is 31-40°C.

3. A multi-layered thermochromic coating according to claim 2, characterized in that: The thermochromic microcapsule powder includes 31°C thermochromic microcapsule powder, 35°C thermochromic microcapsule powder, 38°C thermochromic microcapsule powder and 40°C thermochromic microcapsule powder, with a mass ratio of 1-2:0.5-1:0.5-1:0.5-1.5, giving the coating a multi-level color-changing property of yellow, orange, red and purple as the temperature changes.

4. The multi-layered thermochromic coating according to claim 1, characterized in that: The added mass percentage of the thermochromic microcapsule powder to the water-soluble polyurethane is 1-5%.

5. The multi-layered thermochromic coating according to claim 1, characterized in that: In the multi-layer thermochromic coating, the addition amount of the thermochromic microcapsule powder is 2% of the mass of the water-soluble polyurethane, and it is mixed with 31°C thermochromic microcapsule powder, 35°C thermochromic microcapsule powder, 38°C thermochromic microcapsule powder, and 40°C thermochromic microcapsule powder in a mass ratio of 2:1:1:

1.

6. A method for preparing a multi-layered thermochromic fabric, characterized in that: Four thermochromic microcapsule powders in different temperature ranges are selected, added into water-soluble polyurethane, stirred and fully blended to obtain a multi-layered thermochromic coating; the multi-layered thermochromic coating is applied on the surface of fabric, dried, and a multi-layered thermochromic fabric is obtained.

7. The method for preparing a multi-layered thermochromic fabric according to claim 6, characterized in that: Stirring time for complete blending is ≥ 7 min.

8. The method for preparing a multi-layered thermochromic fabric according to claim 6, characterized in that: The coating thickness is 0.15~0.20 mm.

9. The method for preparing a multi-layered thermochromic fabric according to claim 6, characterized in that: The drying temperature is 65~95℃ and the drying time is 10~50min.

10. A multi-layered thermochromic fabric, characterized in that: The invention comprises a coating layer and a fabric, wherein the coating layer is obtained by coating a multi-layer thermochromic coating on the fabric surface and drying the coating, wherein the multi-layer thermochromic coating comprises a water-soluble polyurethane and four thermochromic microcapsule powders in different temperature ranges, and the multi-layer thermochromic fabric is endowed with four levels of thermochromism, and the color change temperature range is 31-40°C.

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