Temperature adaptive multifunctional coated bio-based ptt fabric and method of making same

Abstract

The present application relates to temperature self-adaptive multifunctional coating bio-based PTT fabric and its preparation method, belong to functional fabric technical field.The preparation method of the present application comprises the following steps: S1, cellulose acetate, pore forming agent, thermochromic microcapsule and nano negative ion powder are added into organic solvent, after stirring uniformly, precursor solution is obtained through cooling;S2, the precursor solution is coated on the surface of bio-based PTT fabric, then the surface of bio-based PTT fabric coated with precursor solution is immersed in 15 DEG C-30 DEG C cold water bath for 8h-16h to carry out phase separation, and temperature self-adaptive multifunctional coating bio-based PTT fabric is obtained through drying.By introducing thermochromic microcapsule and nano negative ion powder, not only the coating is given radiation cooling function, but also the synergistic effect of the two kinds of materials and radiation cooling coating is used, the radiation cooling performance of the coating is strengthened, and a better negative oxygen ion release environment is created for nano negative ion powder.

Description

Technical Field

[0001] This invention belongs to the field of functional fabric technology, and particularly relates to temperature-adaptive multifunctional coated bio-based PTT fabric and its preparation method. Background Technology

[0002] Against the backdrop of escalating global warming and a growing crisis in traditional energy supplies, energy conservation and emission reduction have become core drivers of global industrial development. Passive radiative cooling technology, with its unique advantages of requiring no additional energy input and providing continuous cooling around the clock, has become a green and environmentally friendly solution for addressing high-temperature environments, attracting widespread attention from academia and industry in recent years. The core mechanism of passive radiative cooling materials lies in their ability to efficiently reflect solar radiation in the 200nm-2500nm wavelength range to reduce energy absorption, while simultaneously radiating heat efficiently to the outside environment through an atmospheric window of 8μm-13μm, thus lowering the material's own temperature below the ambient temperature and achieving a passive cooling effect. Currently, passive radiative cooling materials have shown broad application prospects in various fields such as building energy conservation, transportation, and smart clothing, and a series of systematic research results have been achieved in related technical fields.

[0003] In terms of optimizing the core passive radiative cooling performance, researchers have focused on improving the optical performance by precisely controlling the micro- and nano-structures of the coating. For example, patent CN112250973A discloses a porous radiative cooling film and its preparation method. This technology constructs anisotropic microporous structures by precisely controlling the phase separation behavior during the film formation process, enabling the film to have excellent reflectivity in the solar radiation band and exhibit efficient emission characteristics in the mid-infrared radiation band, successfully achieving efficient daytime radiative cooling.

[0004] To overcome the limitations of traditional cooling materials' "static cooling" and endow them with dynamic environmental adaptability, intelligent response materials are gradually being introduced into the field of passive radiative cooling. Patent CN114736566A discloses a superhydrophobic, self-cleaning, temperature-adaptive radiative cooling coating and its preparation method. This technology innovatively integrates thermochromic phase change microcapsules into the coating system, enabling the coating's optical properties to adaptively adjust with changes in ambient temperature. This represents a preliminary technological upgrade from "static cooling" to "dynamic temperature regulation," improving the applicability of cooling materials in complex environments.

[0005] In the modification and application of functional fillers, the introduction of various environmental functional materials has become an important path to expand the added value of coatings. Among them, tourmaline, as an environmental functional material with the ability to release negative oxygen ions, has been widely studied for use in the preparation of functional coatings. Patent CN112044295A discloses a nano-tourmaline dispersion and its preparation method, which effectively solves the problem of agglomeration and sedimentation of nano-tourmaline particles in the matrix material through an innovative dispersion process. In addition, to improve the practical application performance of coatings, multifunctional integration has become a technological development trend. Patent CN110483924A discloses a superhydrophobic self-cleaning radiative cooling film and its preparation method, which expands the application scenarios of coatings by constructing a synergistic system of superhydrophobic surface structure and radiative cooling function.

[0006] Although passive radiation cooling coating technology has made phased progress, there are still many technical bottlenecks that need to be addressed in practical applications: First, the problem of functional limitation is prominent. Most existing passive radiation cooling coatings only focus on the core function of cooling and lack additional functions such as negative oxygen ion release, making it difficult to meet the demand for multifunctional integration of materials in scenarios such as smart clothing and interior decoration. Second, existing negative oxygen ion releasing coatings suffer from unreasonable pore structure design, resulting in obstructed negative oxygen ion release channels and low release efficiency, failing to fully exert their environmental optimization effect. Third, the dynamic temperature regulation capability is lacking. Most coatings are still in a static cooling mode and cannot adaptively adjust their cooling performance according to changes in ambient temperature, resulting in poor stability of cooling effect in environments with temperature fluctuations. Fourth, there are shortcomings in the preparation process. Some technical solutions have problems such as cumbersome process steps, high equipment requirements, and expensive raw material costs, which seriously restrict their large-scale production and market promotion.

[0007] Therefore, developing a multifunctional coated bio-based poly(propylene terephthalate) (PTT) fabric that combines efficient passive radiative cooling, full release of negative oxygen ions, and dynamic temperature adaptive regulation, while also having a simple preparation process and low production cost, can not only effectively compensate for the shortcomings of existing technologies, but also further expand the application scenarios of passive radiative cooling materials in high-end fields such as smart wearables and interior soft furnishings, thus possessing significant academic value and industrial application significance. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the problems of the existing coated fabrics having single function, low negative oxygen ion release efficiency, no dynamic temperature regulation capability, and some complicated preparation processes and high production costs.

[0009] To address the aforementioned technical issues, this invention provides a temperature-adaptive multifunctional coated bio-based PTT fabric and its preparation method. By introducing thermochromic microcapsules and nano-negative ion powder, the coating is not only endowed with radiative cooling function, but also, through the synergistic effect of the two materials and the radiative cooling coating, the coating's radiative cooling performance is enhanced while creating a better environment for the release of negative oxygen ions by the nano-negative ion powder. As a multi-element natural mineral, the nano-negative ion powder has a high negative ion generation capacity and far-infrared emissivity. Its special polar crystal structure enables it to continuously ionize and persistently release negative air ions. The thermochromic microcapsules, by lightening their color when the temperature rises to improve the cooling efficiency of the radiative cooling coating and darkening their color when the temperature falls to promote the coating's temperature recovery, cyclically form an effective temperature difference, thereby driving the nano-negative ion powder to release negative oxygen ions, ultimately achieving a dynamic cooling effect for the fabric in summer.

[0010] The first objective of this invention is to provide a method for preparing a temperature-adaptive multifunctional coated bio-based PTT fabric, comprising the following steps: S1. Add cellulose acetate, pore-forming agent, thermochromic microcapsules and nano negative ion powder to an organic solvent, stir at 1200rpm-1800rpm for 0.5h-1.5h at 70℃-110℃, and obtain the precursor solution after cooling. S2. The precursor solution described in S1 is coated onto the surface of the bio-based PTT fabric. Then, the surface of the bio-based PTT fabric coated with the precursor solution is immersed in a cold water bath at 15℃-30℃ for 8h-16h to perform phase separation. After drying, the temperature-adaptive multifunctional coated bio-based PTT fabric is obtained.

[0011] In one embodiment of the present invention, in S1, the porogen is selected from one or more of polyethylene glycol (PEG), ammonium polyphosphate, polyvinylpyrrolidone (PVP), and urea.

[0012] Furthermore, in S1, the pore-forming agent is polyethylene glycol (PEG), which has the dual functions of pore formation and plasticization. It can effectively control the pore size, pore distribution and pore structure of the coating, increase the pore density, improve the flexibility of the coating and enhance its chemical stability.

[0013] In one embodiment of the present invention, in S1, the thermochromic microcapsule includes a wall material and a core material; the core material includes a color developer, a color developer aid, and a solvent; The mass ratio of the wall material to the core material is (1-3):10; The mass ratio of the color developer, color developer aid and solvent is 1:(1-3):(85-95); The wall material is selected from one or more of melamine-formaldehyde resin, polyurea, polyurethane, and epoxy resin; The colorimetric agent is selected from fluorescein and / or crystal violet lactone; The color-developing agent is selected from bisphenol A and / or octylphenol; The solvent is selected from one or more of tetradecyl alcohol, hexadecyl alcohol, stearic acid, palmitic acid, lauric acid and isopropyl palmitate.

[0014] In one embodiment of the present invention, the particle size of the thermochromic microcapsules is 1μm-10μm.

[0015] In one embodiment of the present invention, in S1, the nano-negative ion powder includes lanthanum oxide, cerium oxide, zinc oxide, and titanium dioxide; it can serve as micro-nucleation sites during the non-solvent-induced phase separation process, effectively ensuring that the pore size of the cellulose acetate skeleton is precisely distributed in the high-efficiency scattering range of 0.3μm-0.7μm; at the same time, by utilizing the potential difference effect between the multi-component metal oxides in the composite powder, it can not only couple with the thermal stress generated by the thermochromic microcapsules to construct a dynamic electronic excitation chain, thereby solving the technical problem of the decay of the single-component negative ion release efficiency over time, but also, without affecting the color-changing sensitivity of the coating, further enhance the radiation cooling performance of the coating by leveraging its unique high infrared emissivity and synergistic effect with the radiation characteristics of the cellulose acetate skeleton; And / or, the particle size of the nano-negative ion powder is 0.5μm-5μm.

[0016] In one embodiment of the present invention, in S1, the organic solvent is selected from one or more of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, N-methylpyrrolidone and dimethyl sulfoxide.

[0017] In one embodiment of the present invention, in S1, the mass ratio of cellulose acetate, pore-forming agent, thermochromic microcapsules, and nano-negative ion powder is 10:(9-13):(0.8-1.2):(0.8-1.2). And / or, the concentration of cellulose acetate in the precursor solution is 150 mg / mL to 180 mg / mL.

[0018] In one embodiment of the present invention, in S2, the coating amount of the precursor solution is 10 g / m 2 -50g / m 2 The coating amount refers to the mass of precursor loaded on a unit area of ​​the substrate fabric. When this parameter is too low, the coating cannot completely cover the fabric substrate, making it difficult to achieve the expected cooling and heat preservation performance. When the parameter is too high, it can easily lead to a deterioration in the fabric's hand feel.

[0019] In one embodiment of the present invention, in S2, the drying method is air drying or oven drying; And / or, the drying is performed at 50℃-70℃ for 2h-6h.

[0020] A second objective of this invention is to provide a temperature-adaptive multifunctional coated bio-based PTT fabric prepared by the method described.

[0021] The technical solution of the present invention has the following advantages compared with the prior art: (1) The preparation method of the present invention introduces thermochromic microcapsules and nano-negative ion powder into the precursor solution, uses cellulose acetate as the skeleton and a pore-forming agent to assist in pore formation, and relies on non-solvent-induced phase separation technology to construct an anisotropic porous self-adhesive radiation cooling coating with a pore size of 0.3μm-0.7μm on the bio-based PTT fabric. The pore size is precisely matched to the high scattering range of the solar spectrum and can also serve as a carrier microcavity for thermochromic microcapsules and nano-negative ion powder. At the same time, the -CH3, C=O, and COC groups in the cellulose acetate molecular chain have strong absorption vibration peaks in the atmospheric window band of 8μm-13μm, which can be converted into high thermal emissivity according to Kirchhoff's radiation law. Moreover, it can form a suitable viscosity in organic solvents, which can stably bind the thermochromic microcapsules to the skeleton structure and prevent them from settling to the bottom of the pores.

[0022] (2) In the temperature-adaptive multifunctional coating bio-based PTT fabric of the present invention, thermochromic microcapsules are dispersed in the cellulose acetate (CA) skeleton and partially exposed on the pore walls. Relying on the heterogeneity of the thermal expansion coefficient between cellulose acetate and thermochromic components, and the anisotropic pore structure constructed by non-solvent-induced phase separation (NIPS) technology, the microcapsules have excellent intelligent thermal regulation characteristics. Above 20°C, they are white and highly reflective to enhance radiative cooling, and below 20°C, they switch to dark and low-reflective to enhance heat preservation. When the ambient temperature fluctuates, the micro-thermal stress generated between the components can be non-uniformly conducted through the porous network. The dynamic change of such micro-stress can provide continuous mechanical excitation for the embedded nano-negative ion powder, causing its electric dipole moment to deflect and enhancing the piezoelectric effect, thereby significantly improving the instantaneous release efficiency of negative oxygen ions. This dynamic regulation process not only coordinates the high reflectivity and high emission performance of the coating, but also realizes the deep functional integration of efficient cooling of the coating and autonomous release of negative oxygen ions.

[0023] (3) The temperature-adaptive multifunctional coating bio-based PTT fabric of the present invention constructs a cellulose acetate network with a specific pore size through non-solvent-induced phase separation (NIPS) process, forming an optical-thermal-electrical three-in-one response system. The thermochromic microcapsules act as reflectivity adjustment switches and can generate spontaneous temperature fluctuations through temperature adaptive changes, thereby serving as a dynamic excitation source to continuously activate the piezoelectric effect of nano negative ion powder, fundamentally solving the core problem of poor negative ion release channels and low efficiency of traditional coatings. At the same time, the microporous network formed by the NIPS process creates a semi-closed dry microenvironment inside the coating, which can effectively isolate the neutralization effect of high external humidity on negative ions, so that the nano negative ion powder not only releases a large amount, but also has an effective activity time that is 3-5 times longer than that of traditional coatings, which is also the key to achieving long-term air purification function.

[0024] (4) The temperature-adaptive multifunctional coated bio-based PTT fabric of the present invention utilizes the refractive index difference between the cellulose acetate skeleton and the thermochromic microcapsule interface to construct multiple total internal reflection paths. After sunlight enters the coating, it is not scattered in a straight line, but repeatedly oscillates and reflects between the specific pore size of the cellulose acetate skeleton and the thermochromic microcapsule. This not only increases the optical path to improve reflectivity, but more importantly, it prolongs the contact time between photons and thermochromic particles, effectively improving the temperature sensitivity and achieving a second-level color change response. In the summer, when the temperature is high, the coating can still maintain a stable cooling effect under external temperature fluctuations. Under sunlight, its surface temperature can be 5℃-15℃ lower than the ambient temperature. In the winter, when the temperature is low, the ambient temperature does not reach the color change critical point (20℃) of the thermochromic microcapsule. The coating always appears dark to absorb solar radiation to achieve a temperature rise of 2℃-8℃. This stable temperature change generated under sunlight can provide reliable environmental parameters for the release of negative oxygen ions by the nano negative ion powder.

[0025] (5) The preparation method described in this invention has the advantages of simple process and low cost, which can meet the needs of large-scale production. At the same time, the cellulose acetate matrix is ​​biodegradable, the nano negative ion powder is natural and non-toxic, and the scheme of coating bio-based PTT fabric with cellulose acetate precursor solution is more conducive to product recycling and is in line with the concept of green manufacturing. Attached Figure Description

[0026] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a pore size distribution diagram of the temperature-adaptive multifunctional coating of the present invention; Figure 2 This is a schematic diagram of the daytime passive radiation cooling performance testing device of the present invention; wherein, (a) is a schematic diagram of the radiation cooling performance testing device, and (b) is a schematic diagram of the testing environment; Figure 3 The images show physical pictures of the PTT fabric of the present invention and the temperature-adaptive multifunctional coated PTT fabric prepared in Example 1; wherein, the left image is the PTT fabric and the right image is the temperature-adaptive multifunctional coated PTT fabric. Figure 4 The spectral reflectance diagrams are for the PTT fabric of the present invention and the temperature-adaptive multifunctional coated PTT fabric prepared in Example 1. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0028] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0029] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In this invention, unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0031] In this invention, unless otherwise stated, the cellulose acetate used in the embodiments of this invention was purchased from Shanghai Maclean Biochemical Co., Ltd., with a molecular weight of approximately 60,000.

[0032] In this invention, unless otherwise stated, the polyethylene glycol used in the embodiments of this invention is polyethylene glycol 400 (PEG-400).

[0033] In this invention, unless otherwise stated, the polyvinylpyrrolidone used in the embodiments of this invention was purchased from Sinopharm Reagent Co., Ltd.

[0034] In this invention, unless otherwise stated, the thermochromic microcapsules used in the embodiments of this invention have a particle size of 1μm-10μm, the wall material is melamine-formaldehyde resin, and the core material is composed of crystal violet lactone, bisphenol A and tetradecyl alcohol in a mass ratio of 1:2:90, and the mass ratio of wall material to core material is 2:10.

[0035] In this invention, unless otherwise stated, the nano-negative ion powder used in the embodiments of this invention was purchased from Xuancheng Jingrui New Materials Co., Ltd., model JR-NF50, with a particle size of 0.5μm-5μm. Example 1

[0036] The temperature-adaptive multifunctional coated PTT fabric and its preparation method in this embodiment specifically include the following steps: S1, 10g cellulose acetate, 10g polyethylene glycol, 1g polyvinylpyrrolidone, 1g thermochromic microcapsules, 1g nano-negative ion powder and 60mL N,N-dimethylacetamide were added to a round-bottom flask. The mixture was then magnetically stirred at 1500rpm for 1h under reflux condensation at 95℃ to ensure that all components were fully dissolved. The mixture was then cooled to room temperature to obtain the precursor solution.

[0037] S2. The precursor solution was applied using a scraper at a concentration of 30 g / m³. 2 The coating was uniformly applied to the surface of the bio-based PTT fabric. After standing for 2 minutes, the PTT fabric coated with the precursor solution was immersed in a 20°C cold water bath for 12 hours to complete phase separation. After drying at room temperature, the temperature-adaptive multifunctional coated PTT fabric was obtained. Comparative Example 1

[0038] It is basically the same as Example 1, except that no nano negative ion powder is added. Comparative Example 2

[0039] The method is basically the same as in Example 1, except that the amount of nano negative ion powder used is 2g. Comparative Example 3

[0040] The method is basically the same as in Example 1, except that the amount of nano negative ion powder used is 3g. Comparative Example 4

[0041] The method is basically the same as in Example 1, except that the amount of nano negative ion powder used is 4g. Comparative Example 5

[0042] It is basically the same as Example 1, except that thermochromic microcapsules are not added. Comparative Example 6

[0043] The method is basically the same as in Example 1, except that the amount of thermochromic microcapsules used is 1.5g. Comparative Example 7

[0044] The method is basically the same as in Example 1, except that the amount of thermochromic microcapsules used is 2g. Comparative Example 8

[0045] The method is basically the same as in Example 1, except that the amount of thermochromic microcapsules used is 2.5g. Comparative Example 9

[0046] The basic structure is the same as in Example 1, except that cellulose acetate is replaced with polylactic acid. Comparative Example 10

[0047] It is basically the same as Example 1, except that polyethylene glycol is not added. Comparative Example 11

[0048] The basic structure is the same as in Example 1, except that the thermochromic microcapsules are replaced with vanadium dioxide. Test Example 1

[0049] Based on Example 1, pore size analysis was performed on the temperature-adaptive multifunctional coating in the temperature-adaptive multifunctional coated PTT fabric, and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the temperature-adaptive multifunctional coating has a concentrated pore size distribution in the 0.3μm-0.7μm range. This range precisely matches the optimal range for Mie scattering. When sunlight shines on the coating, the incident light undergoes strong Mie scattering in the pore structure with this specific pore size. Simultaneously, combined with the multiple total internal reflection paths constructed by the refractive index difference between the cellulose acetate skeleton and the thermochromic microcapsule interface, sunlight entering the coating is not scattered linearly, but rather oscillates and reflects repeatedly between this specific pore size of the cellulose acetate skeleton and the thermochromic microcapsules. This not only extends the optical path but also maximizes the scattering efficiency for the 200nm-25nm range. The reflectance efficiency in the 00nm solar spectrum band; in addition, this pore size range can not only serve as a carrier microcavity for thermochromic microcapsules and nano negative ion powder, stabilizing the functional particles and preventing their sedimentation, but also provide a smooth channel for the release of negative oxygen ions. Combined with the semi-closed dry microenvironment formed by the non-solvent-induced phase separation process, it effectively isolates the neutralization effect of high external humidity on negative ions. Combined with the continuous temperature fluctuations generated by the thermochromic microcapsules with temperature changes (white high reflectance state above 20℃, dark low reflectance state below 20℃), it provides continuous mechanical excitation for nano negative ion powder, enhancing its piezoelectric effect. Test Example 2

[0050] Performance tests were conducted on the coated PTT fabrics (modified PTT fabrics) and unmodified PTT fabrics prepared in the examples and comparative examples: (1) Reflectance test: The spectral reflectance in the 200nm-2500nm band was tested and characterized using a Shimadzu UV3600 tester with BaSO4 as the standard backplate under AM1.5 solar spectrum conditions. (2) Temperature change test: such as Figure 2As shown, a LIANYI SH-X (SH-16XL) multi-temperature tester manufactured by Dongguan Lianyi Instrument Co., Ltd. was used to measure and record temperature data. A radiative cooling performance testing device was constructed using a LIANYI K-type thermocouple. This thermocouple has a relative error of less than 0.5℃ and can be used to monitor the ambient temperature and the surface temperature of the upper and lower layers of the sample. The testing device includes a polystyrene foam box wrapped in aluminum foil to minimize heat transfer and reflect sunlight. (2) Negative oxygen ion concentration: The amount of negative oxygen ions released by the fabric was measured using a COM-3200PRO II air negative ion detector; Figures 3-4 Table 1 shows the final measured properties of the modified PTT fabric and the unmodified PTT fabric: Table 1

[0051] from Figures 3-4 As shown in Table 1, the coating is continuous and uniform on the surface of the PTT fabric. Compared to the uncoated PTT fabric, the coating is distinctly white with a rough texture, which enhances the diffuse reflection effect. The coating thickness is 120 μm, and the pore size is concentrated in the high-efficiency scattering range of 0.3 μm-0.7 μm. In terms of performance, the fabric exhibits a reflectivity of up to 96.4% at high temperatures (above 20℃) and drops to 38.2% at low temperatures (below 20℃). It achieves a cooling effect of 11.7℃ outdoors in summer and a warming effect of 7.5℃ in winter, with a negative ion release rate of 5500 ions / (cm³). 3 •s), with overall performance far exceeding that of unmodified PTT fabrics.

[0052] Comparing Example 1 and Comparative Examples 1-4, it can be seen that the negative oxygen ion release of Comparative Example 1 (without nano negative ion powder) is <100 ions / (cm³). 3 •s), the temperature drop was only 6.1℃ and the temperature rise was 3.8℃; the negative oxygen ion release of comparative examples 2-4 (nano negative ion powder dosage of 2g, 3g, 4g) increased from 2800 to 3500 ions / (cm³) with increasing dosage. 3However, the solar reflectivity and cooling rate were significantly lower than in Example 1, and the coating rigidity increased while the adhesion to the substrate decreased significantly. This is because the amount of nano-negative ion powder is positively correlated with the amount of negative oxygen ions released. Whether the amount is appropriate directly affects the structure and function of the coating. When the amount is excessive, the nanoparticles will agglomerate, causing the internal structure of the coating to become dense, destroying the porous skeleton of cellulose acetate, reducing the solar spectrum reflectivity and radiation cooling performance of the coating. At the same time, the enhanced interaction between particles will also lead to an increase in coating rigidity and a decrease in adhesion. When the amount is too small, the potential difference effect of the multi-component metal oxide cannot be fully utilized, making it difficult to couple with the thermal stress of the thermochromic microcapsules, resulting in incomplete construction of the dynamic electronic excitation chain, ultimately causing insufficient release of negative oxygen ions. When the amount is appropriate, the nano-negative ion powder can not only serve as micro-nucleation points to ensure the precise distribution of coating pore size, but also enhance the piezoelectric effect through synergistic effect with the thermochromic microcapsules, thereby achieving a balance between coating structure and function.

[0053] Comparing Example 1 and Comparative Examples 5-8, it can be seen that the coating reflectance of Comparative Example 5 (without thermochromic microcapsules) showed no temperature-dependent difference (88.4% in summer / 88.5% in winter), with a temperature drop of only 5.1℃ in summer and no heat preservation effect in winter (temperature increase of 0℃). The release of negative oxygen ions was only 500 ions / (cm³). 3 •s); Although the release of negative oxygen ions in comparative examples 6-8 (1.5g, 2g, and 2.5g of thermochromic microcapsules) was slightly increased, the reflectivity and cooling rate were not significantly improved, and the adhesion between the coating and the substrate deteriorated, resulting in a stiff feel. This is because thermochromic microcapsules, as the core trigger source of "dynamic temperature regulation-negative ion excitation," not only regulate the reflectivity of the coating due to their "high-temperature white / low-temperature deep" characteristics, but also generate continuous temperature fluctuations. They provide mechanical excitation for the nano-negative ion powder through the dynamic conduction of microscopic thermal stress, thereby enhancing the piezoelectric effect. Without the addition of these microcapsules, the system cannot spontaneously generate a temperature difference, resulting in insufficient negative ion excitation. Furthermore, the fixed reflectivity directly leads to an imbalance in the cooling and heat preservation functions of the coating. When the amount of microcapsules is excessive, they will aggregate and destroy the uniformity of the porous structure. The mutual obstruction between particles will also reduce the reflectivity of the coating. At the same time, excessive microcapsules will increase the interfacial tension between the coating and the substrate, resulting in a decrease in the coating's bonding strength and a worse feel. When the amount of microcapsules is appropriate, it can ensure that they are uniformly dispersed in the cellulose acetate skeleton and partially exposed on the pore walls. It can also generate effective microscopic stress by utilizing the heterogeneity of the coefficient of thermal expansion, ultimately achieving the synergistic effect of coating temperature regulation and negative ion release.

[0054] Comparing Example 1 and Comparative Example 9, it can be seen that Comparative Example 9 (cellulose acetate replaced with polylactic acid) has a reflectivity of only 87.2%, a temperature drop of 4.5℃ in summer, a temperature rise of 1.9℃ in winter, and a negative oxygen ion release of 2100 ions / (cm³). 3•s), and the coating is prone to peeling and has extremely poor adhesion. This is because cellulose acetate has good flexibility and interfacial adhesion, and can form a stable bond with substrates such as polyester and nylon. It is also easily soluble in organic solvents such as N,N-dimethylacetamide, and can form a uniform precursor solution with pore-forming agents and functional particles, forming a continuous porous structure after curing. The strong absorption vibration peaks of the -CH3, C=O, and COC groups in the cellulose acetate molecular chain in the 8μm-13μm atmospheric window can be converted into high thermal emissivity, enhancing radiative cooling. Polylactic acid has poor flexibility, weak interfacial compatibility, and poor dispersion of functional particles, which leads to the aggregation of dopants in the coating at the interface and a decrease in adhesion. At the same time, its molecular structure lacks the functional groups required for efficient radiative cooling, and its optical and thermal properties are inferior to those of cellulose acetate.

[0055] Comparing Example 1 and Comparative Example 10, it can be seen that the coating of Comparative Example 10 (without polyethylene glycol) has obvious defects and an incomplete surface, with a reflectivity of only 76.3%, a temperature drop of only 0.8℃ in summer, a temperature rise of 1.4℃ in winter, and a negative oxygen ion release of 1100 ions / (cm³). 3 •s). This is because polyethylene glycol has both pore-forming and plasticizing effects. It can precisely control the pore size, pore distribution, and pore density of the coating, ensuring that the pore size is concentrated in the high-efficiency range of 0.3μm-0.7μm, providing a structural basis for improved reflectivity and negative ion release. It can also improve the flexibility of cellulose acetate, enhance the chemical stability of the coating, and improve its adhesion to the substrate. Without the addition of polyethylene glycol, the coating has poor pore-forming effect, with sparse pores and uneven pore size distribution, which cannot form an effective light scattering path and negative ion release channel. At the same time, the rigidity of cellulose acetate is too strong, and cracks and defects are prone to occur after curing, resulting in a significant decrease in reflectivity and cooling performance, and hindering the release of negative oxygen ions.

[0056] Comparing Example 1 and Comparative Example 11, it can be seen that the coating reflectance of Comparative Example 11 (where the thermochromic microcapsules were replaced with vanadium dioxide) showed no significant temperature-dependent difference (90.6% in summer / 90.4% in winter), with a temperature drop of only 6.4°C in summer and no heating or heat preservation effect in winter (temperature rise of 0°C). The release of negative oxygen ions was only 600 ions / (cm³). 3•s). This is because vanadium dioxide has a phase transition temperature of approximately 68°C, far exceeding the human comfort range (18°C-26°C) and typical indoor and outdoor temperatures. In daily use, it is difficult to reach its critical phase transition point, preventing the coating from achieving temperature self-adjustment and ultimately causing an imbalance between cooling and insulation functions. Simultaneously, as a metallic particle, vanadium dioxide has a relatively high density and mass, making it prone to settling to the bottom of the coating during precursor solution coating and phase separation. This phenomenon not only disrupts the uniformity of the porous structure within the coating but also results in a lack of effective color-changing components on the coating surface, preventing the formation of a refractive index difference with the cellulose acetate skeleton to construct multiple total internal reflection paths, thus allowing sunlight to escape. After incident light, repeated oscillations and reflections are difficult to achieve, resulting in poor optical path extension and a significant decrease in the coating's reflection efficiency for the 200nm-2500nm solar spectrum. Vanadium dioxide, unable to achieve temperature-adaptive color change, cannot generate spontaneous temperature fluctuations, leading to a lack of dynamic thermal stress excitation in the system. This results in limited deflection of the electric dipole moment of the nano-negative ion powder and difficulty in activating the piezoelectric effect. Its sedimentation characteristics also block some negative ion release channels, further reducing the amount of negative oxygen ions released. In addition, the metallic optical properties of vanadium dioxide make its reflection mechanism singular, unable to synergize with the infrared emission characteristics of the cellulose acetate skeleton.

[0057] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a temperature-adaptive multifunctional coated bio-based PTT fabric, characterized in that, Includes the following steps: S1. Add cellulose acetate, pore-forming agent, thermochromic microcapsules and nano negative ion powder to an organic solvent, stir at 1200rpm-1800rpm for 0.5h-1.5h at 70℃-110℃, and obtain the precursor solution after cooling. S2. The precursor solution described in S1 is coated onto the surface of the bio-based PTT fabric. Then, the surface of the bio-based PTT fabric coated with the precursor solution is immersed in a cold water bath at 15℃-30℃ for 8h-16h to perform phase separation. After drying, the temperature-adaptive multifunctional coated bio-based PTT fabric is obtained.

2. The method for preparing temperature-adaptive multifunctional coated bio-based PTT fabric according to claim 1, characterized in that, In S1, the pore-forming agent is selected from one or more of polyethylene glycol, ammonium polyphosphate, polyvinylpyrrolidone, and urea.

3. The method for preparing temperature-adaptive multifunctional coated bio-based PTT fabric according to claim 1, characterized in that, In S1, the thermochromic microcapsule includes a wall material and a core material; the core material includes a color developer, a color developer aid, and a solvent. The mass ratio of the wall material to the core material is (1-3):10; The mass ratio of the color developer, color developer aid and solvent is 1:(1-3):(85-95); The wall material is selected from one or more of melamine-formaldehyde resin, polyurea, polyurethane, and epoxy resin; The colorimetric agent is selected from fluorescein and / or crystal violet lactone; The color-developing agent is selected from bisphenol A and / or octylphenol; The solvent is selected from one or more of tetradecyl alcohol, hexadecyl alcohol, stearic acid, palmitic acid, lauric acid and isopropyl palmitate.

4. The method for preparing temperature-adaptive multifunctional coated bio-based PTT fabric according to claim 1, characterized in that, In S1, the particle size of the thermochromic microcapsules is 1μm-10μm.

5. The method for preparing temperature-adaptive multifunctional coated bio-based PTT fabric according to claim 1, characterized in that, In S1, the nano-negative ion powder includes lanthanum oxide, cerium oxide, zinc oxide, and titanium dioxide; And / or, the particle size of the nano-negative ion powder is 0.5μm-5μm.

6. The method for preparing temperature-adaptive multifunctional coated bio-based PTT fabric according to claim 1, characterized in that, In S1, the organic solvent is selected from one or more of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

7. The method for preparing temperature-adaptive multifunctional coated bio-based PTT fabric according to claim 1, characterized in that, In S1, the mass ratio of cellulose acetate, pore-forming agent, thermochromic microcapsules, and nano-negative ion powder is 10:(9-13):(0.8-1.2):(0.8-1.2). And / or, the concentration of cellulose acetate in the precursor solution is 150 mg / mL to 180 mg / mL.

8. The method for preparing temperature-adaptive multifunctional coated bio-based PTT fabric according to claim 1, characterized in that, In S2, the coating amount of the precursor solution is 10 g / m. 2 -50g / m 2 .

9. The method for preparing temperature-adaptive multifunctional coated bio-based PTT fabric according to claim 1, characterized in that, In S2, the drying method is air drying or oven drying; And / or, the drying is performed at 50℃-70℃ for 2h-6h.

10. Temperature-adaptive multifunctional coated bio-based PTT fabric prepared by the method of any one of claims 1-9.

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