A weather-resistant multi-spectrum selective adjustment film and a preparation method thereof

Abstract

This invention discloses a low-haze multi-band blocking architectural film and its preparation method, belonging to the field of building energy-saving film technology. The architectural film comprises a PET protective layer, a hardening layer, a TPU substrate, a functional installation adhesive layer, and a release film protective layer, stacked sequentially. The functional installation adhesive layer contains acrylic pressure-sensitive adhesive, near-infrared absorbing functional particles, mid- and far-infrared reflective functional particles, an ultraviolet absorber, and a solvent. The near-infrared absorbing functional particles are cesium tungsten oxide nanoparticles modified with metal elements, and the mid- and far-infrared reflective functional particles are nano-metal wires. The visible light transmittance of this architectural film is 40-70%, the ultraviolet blocking rate is ≥99%, the near-infrared blocking rate is >90%, the mid- and far-infrared blocking rate is >90%, and the haze is <0.6%. This invention achieves efficient blocking of ultraviolet and multi-band infrared light through the multi-band synergistic blocking design of the functional installation adhesive layer, while also exhibiting low haze and high weather resistance, making it suitable for external building curtain walls. The preparation process is simple and suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of building energy-saving membrane technology, specifically relating to a low-haze multi-band blocking building membrane and its preparation method, and particularly to a building membrane that has ultraviolet blocking, near-infrared blocking and mid-far-infrared blocking functions, while also having low haze and high weather resistance, and is suitable for external application to building curtain walls. Background Technology

[0002] As a crucial component of modern architecture, the light transmittance and energy efficiency of building curtain walls have become core requirements. In summer, ultraviolet radiation from the sun can cause indoor furniture and fabrics to age, while near-infrared radiation can raise indoor temperatures and increase air conditioning energy consumption. In winter, mid- and far-infrared radiation from indoor objects can escape through the curtain wall, reducing indoor insulation. Statistics show that thermal radiation from indoor objects accounts for 30%-40% of indoor heat loss, making it vital for winter insulation.

[0003] Several technical solutions have been proposed in the field of building energy-saving films. For example, patent application CN118126640A published by the Institute of Engineering Thermophysics, Chinese Academy of Sciences, proposes a mid-to-far infrared energy blocking film comprising a protective layer, a nano-coating layer, a PET substrate, and an adhesive layer. The nano-coating layer is composed of silver nanowires and transparent polymers, primarily targeting the mid-to-far infrared band. While this solution achieves some effect in reducing mid-to-far infrared emissivity, it only blocks the mid-to-far infrared band and cannot simultaneously block the near-infrared band and ultraviolet rays. Furthermore, using PET as the substrate results in limited weather resistance, making it difficult to apply to outdoor application scenarios.

[0004] The same applicant's patent application CN118126617A discloses a scheme that uses silver nanowires and transparent polymers to construct photonic crystal metamaterials. This scheme also only blocks energy in the mid- and far-infrared bands, and has virtually no blocking effect on the near-infrared band. Furthermore, it does not involve improving the dispersibility of nanoparticles or designing for low haze.

[0005] In addition, existing technologies also disclose schemes using cesium tungsten bronze as a near-infrared absorbing material. For example, patent application CN118206374A discloses a cesium tungsten bronze ceramic target and its preparation method for use in energy-saving glass. This target can be used for magnetron sputtering coating, and the resulting cesium tungsten bronze thin film has the characteristics of good near-infrared light shielding effect and high visible light transmittance. However, this scheme has the following shortcomings: First, the investment in magnetron sputtering equipment is high, and the production efficiency is relatively limited; second, the prepared cesium tungsten bronze thin film does not have mid- and far-infrared blocking functions; third, the film is an independent coating layer, which is difficult to integrate with the mounting adhesive layer, resulting in film composite stability problems in practical applications.

[0006] Furthermore, in the research on doping modification of cesium tungsten bronze, existing technologies have reported various metal element doping schemes. For example, patent application CN120882665A discloses a composite tungsten oxide particle, in which the M element in the general formula MxWyOz includes elements selected from alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, etc., and can be used as a near-infrared absorbing material. However, none of the above-mentioned existing technologies involve a technical solution for dispersing Cr-doped cesium tungsten oxide as a functional filler in acrylic pressure-sensitive adhesive for use in the functional installation adhesive layer of building membranes, nor have there been any reports of compounding Cr-doped cesium tungsten oxide with silver nanowires to achieve simultaneous near-infrared and mid-far-infrared blocking.

[0007] Regarding the surface modification of nanoparticles, patent application CN118460012A discloses a modified cesium tungsten bronze powder, the coating material of which includes silane compounds. Existing technologies also disclose methods for surface modification of tungsten bronze particles using silane coupling agents. However, none of the aforementioned prior technologies involve applying silane coupling agent-modified metal-doped cesium tungsten oxide particles to acrylic pressure-sensitive adhesive systems, nor do they address the technical means to simultaneously solve the problems of nanoparticle agglomeration and increased haze in pressure-sensitive adhesives through silane coupling agent modification.

[0008] Regarding the substrate for exterior architectural membranes, existing technologies have disclosed exterior architectural glass films employing a TPU + substrate + TPU sandwich structure, with an anti-fouling coating applied to one TPU layer as the exterior facade. However, existing TPU exterior films primarily address weather resistance issues and do not involve technical solutions for integrating functional nanoparticles into the adhesive layer to achieve multi-band spectral selective blocking.

[0009] In the research field of cesium tungsten bronze, existing literature reports its basic properties as a near-infrared shielding material, but no reports have been found on in-situ doping modification with other metal elements such as chromium, nor on its application in acrylic pressure-sensitive adhesive systems after surface modification with silane coupling agents. Acrylic pressure-sensitive adhesives, due to their good adhesion, film-forming properties, and compatibility, are often used as the installation adhesive layer for architectural membranes. However, plain acrylic pressure-sensitive adhesives do not possess ultraviolet and infrared blocking functions, requiring the addition of functional fillers to achieve energy-saving effects. Chromium-doped cesium tungsten oxide, as a highly efficient near-infrared absorbing material, and silver nanowires, which can achieve mid- and far-infrared reflection, can be combined to achieve multi-band infrared blocking. However, nanoparticles tend to aggregate in pressure-sensitive adhesive systems, which not only affects the blocking effect but also leads to increased film haze.

[0010] In addition, conventional architectural films mostly use PET as the base material, which has poor weather resistance. When exposed to the outdoor environment for a long time, it is prone to yellowing, embrittlement, and peeling, making it difficult to meet the weather resistance requirements of the exterior building industry.

[0011] In summary, the existing technologies have the following common shortcomings: (1) Single function, only able to achieve single-band blocking in near-infrared or mid-far-infrared, unable to simultaneously meet the multi-band blocking requirements of ultraviolet, near-infrared and mid-far-infrared; (2) Insufficient weather resistance, mostly using PET substrate, which ages severely when applied to external application scenarios; (3) High haze, the uneven dispersion of nanoparticles in the adhesive layer leads to a decrease in optical clarity; (4) Poor compatibility between nanoparticles and colloids, cesium oxide tungsten and other nanoparticles are prone to agglomeration in acrylic pressure-sensitive adhesives, which affects the blocking effect. The effect also leads to increased haze; (5) The preparation process is complex. Although processes such as magnetron sputtering can achieve high mid- and far-infrared blocking performance (the mid- and far-infrared blocking rate of some high-end products can reach 85%-95%), the equipment investment is high, the production efficiency is low, it is difficult to scale up production, and it usually cannot integrate near-infrared absorption function and ultraviolet blocking function at the same time; (6) There is no technical solution that integrates in-situ doping of metal elements with cesium tungsten oxide, surface modification of silane coupling agent, mid- and far-infrared reflection of nano-silver wires and weather resistance of TPU substrate. Summary of the Invention

[0012] This invention aims to provide a low-haze multi-band barrier architectural film and its preparation method to overcome the aforementioned shortcomings of existing technologies. The invention disperses metal-doped and modified cesium tungsten oxide nanoparticles (near-infrared absorption core), nano-metal wires (mid- and far-infrared reflection core), and ultraviolet absorbers (ultraviolet blocking core) in an acrylic pressure-sensitive adhesive matrix, forming a functional adhesive layer that provides triple synergistic blocking of ultraviolet, near-infrared, mid- and far-infrared rays. Simultaneously, an aliphatic polycarbonate TPU substrate combined with a solvent-based two-component curing layer ensures weather resistance for external application. Surface modification with a silane coupling agent and a three-stage progressive dispersion process address the nanoparticle agglomeration problem, achieving low haze.

[0013] To achieve the above objectives, the present invention adopts the following technical solution: Option 1: A low-haze multi-band barrier architectural film, characterized in that the architectural film comprises a PET protective layer, a hardening layer, a TPU substrate, a functional installation adhesive layer, and a release film protective layer stacked sequentially. The functional mounting adhesive layer comprises acrylic pressure-sensitive adhesive, near-infrared absorbing functional particles, mid- and far-infrared reflective functional particles, ultraviolet absorber, and solvent; The near-infrared absorbing functional particles are cesium tungsten oxide nanoparticles modified with metal elements, and the mid- and far-infrared reflecting functional particles are nano-metal wires.

[0014] Preferably, the TPU substrate is aliphatic polycarbonate thermoplastic polyurethane with a thickness of 50-80 μm.

[0015] Preferably, the hardened layer is a solvent-based two-component polyurethane coating with a thickness of 1-4 μm.

[0016] Preferably, the functional mounting adhesive layer comprises, based on 100 parts by weight of acrylic pressure-sensitive adhesive, 28-35 parts by weight of solvent, 20-50 parts by weight of near-infrared absorbing functional particles, 4-6 parts by weight of mid- and far-infrared reflective functional particle dispersion, and 0.2-2 parts by weight of ultraviolet absorber.

[0017] Preferably, in the metal element-doped modified cesium tungsten oxide nanoparticles, the metal element is selected from at least one of chromium, iron, cobalt, nickel, and manganese, and the atomic ratio of tungsten, cesium, and the metal element in the cesium tungsten oxide is 1:0.25-0.35:0.015-0.025.

[0018] Preferably, the near-infrared absorbing functional particles are chromium-doped cesium oxide nanoparticles modified with a silane coupling agent, and the grafting amount of the silane coupling agent is 4-10% of the mass of the chromium-doped cesium oxide.

[0019] Preferably, the silane coupling agent is selected from one or more combinations of allyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-(methacryloyloxy)propyltrimethoxysilane.

[0020] Preferably, the diameter of the nanowire is 30-50 nm and the length is 5-30 μm, and it is selected from at least one of silver nanowires, gold nanowires, and copper nanowires.

[0021] Preferably, the nanowires are composed of silver nanowires with diameters of 30 nm and 45 nm in a volume ratio of 2:1.

[0022] The core of the low-haze multi-band barrier building membrane proposed in this invention lies in the system integration and synergistic effect of multiple technical means, rather than the simple superposition of various technical features. Specifically: First, in-situ doping with a hydrothermal reaction ensures the uniform embedding of Cr elements into the cesium tungsten oxide lattice. Combined with surface modification using a silane coupling agent to reduce the surface energy of nanoparticles, the two work synergistically to solve the dispersion problem of nanoparticles in acrylic pressure-sensitive adhesives, enabling near-infrared absorption functional particles to be uniformly dispersed at the nanoscale in the adhesive layer. Second, Cr-doped cesium tungsten oxide (near-infrared absorption) and silver nanowires (mid- and far-infrared reflection) complement each other spectrally. The former selectively absorbs near-infrared photons in the 780-2500nm range through the LSPR effect and small polaron transitions, while the latter reflects mid- and far-infrared electromagnetic waves in the 3-50μm range through the high-frequency dielectric response of free electron gas. The two act independently and without interference in the two dimensions of "absorption" and "reflection," jointly achieving full-band infrared blocking. Third, a chemical bonding interface is formed between the TPU substrate and the functional mounting adhesive layer through corona treatment. This not only enhances interlayer adhesion but also allows the flexibility of TPU to buffer the thermal expansion mismatch between the nanoparticles in the functional adhesive layer and the substrate, further improving the long-term stability of the film. The aforementioned technical means are closely related and mutually reinforcing, forming an inseparable overall technical solution. The resulting comprehensive performance of low haze (<0.6%), high blocking rate (both near-infrared and mid-far-infrared >90%) and excellent weather resistance (1500 hours UV aging ΔE <2.1) cannot be achieved by the superposition of the individual effects of each feature.

[0023] Option 2: A method for preparing a low-haze multi-band barrier architectural film, comprising the following steps: A functional mounting adhesive slurry is coated on the release film protective layer to form a functional mounting adhesive layer with a thickness controlled at 10-25μm, which is then bonded to the corona-treated surface of the TPU substrate. A hardening layer slurry is coated on the other side of the TPU substrate to form a hardened layer with a thickness of 1-4μm, which is then laminated with a PET protective layer.

[0024] Preferably, the preparation method further includes a step of preparing a functional mounting adhesive layer slurry, comprising: Add the solvent to the acrylic pressure-sensitive adhesive and stir at 200-500 r / min to disperse it evenly; Add near-infrared absorbing functional particles, mid- and far-infrared reflective functional particle dispersion and ultraviolet absorber in sequence, and continue stirring for 30-40 minutes; After ultrasonic dispersion for 10-20 minutes, the functional installation adhesive layer slurry is obtained.

[0025] Preferably, in the functional mounting adhesive slurry, the dispersion of mid- and far-infrared reflective functional particles is prepared in advance by mixing nano-metal wires, solvents and acrylic pressure-sensitive adhesives at a mass ratio of 0.1-0.3:2:4 and then sonicating at 25-35 kHz for 6-8 minutes.

[0026] Preferably, the near-infrared absorbing functional particles are prepared through in-situ doping hydrothermal reaction and silane coupling agent surface modification, specifically including: Tungsten source, cesium source and metal dopant source are dissolved in deionized water according to the metal atomic ratio, mineralizing agent is added, pH is adjusted to 4-6, hydrothermal reaction is carried out at 180-200℃ for 10-14h, and then calcined at 450-500℃ in an inert atmosphere for 1.5-2h to obtain metal-doped cesium tungsten oxide powder. The surface of the metal-doped cesium oxide tungsten powder was modified using a silane coupling agent, and then ball-milled until D50 < 30 nm after drying.

[0027] Compared with the prior art, the present invention has the following beneficial effects: Achieve efficient multi-band blocking: It has the functions of blocking ultraviolet rays, near-infrared rays, and mid- and far-infrared rays. The ultraviolet blocking rate is ≥99%, the near-infrared blocking rate is >90%, and the mid- and far-infrared blocking rate is >90%. It can effectively reduce the energy consumption of building air conditioning, achieve the dual energy-saving effect of heat insulation in summer and heat preservation in winter, and protect indoor furniture and fabrics from ultraviolet aging.

[0028] Low haze and high light transmittance: Through silane coupling agent modification and three-stage dispersion process, the nanoparticles are uniformly dispersed, the haze of the film layer is <0.6%, and the visible light transmittance is 40-70%, which takes into account both the clarity of light transmission and energy-saving effect, and is suitable for various building curtain walls.

[0029] High weather resistance, suitable for external application scenarios: It adopts an aliphatic polycarbonate TPU substrate and a solvent-based two-component hardening layer, which has excellent anti-yellowing, abrasion resistance and weather resistance. It can withstand harsh environments such as outdoor wind, rain and ultraviolet radiation. There is no obvious aging, peeling or yellowing after long-term use, making it suitable for external building applications.

[0030] Excellent adhesion and easy installation: The functional installation adhesive layer uses acrylic pressure-sensitive adhesive, which has stable adhesion and can be firmly attached to the building curtain wall. The installation process is simple and convenient, and there is no residue after peeling, which does not damage the curtain wall surface.

[0031] The preparation process is simple and can be mass-produced: the entire preparation process does not require complex equipment, and the steps such as coating, lamination and curing are easy to operate in an industrial manner. Each process parameter is controllable, the production efficiency is high, it is suitable for large-scale mass production, and has good industrial application value.

[0032] The problem of nanoparticle aggregation was solved: chromium-doped cesium tungsten oxide was surface modified by silane coupling agent, which effectively reduced its surface energy and improved its dispersion uniformity in acrylic pressure-sensitive adhesive, avoiding the decline in optical performance and infrared blocking effect caused by aggregation. At the same time, the in-situ doping process ensured that the Cr element was effectively embedded in the cesium tungsten oxide lattice, ensuring near-infrared blocking performance. Detailed Implementation

[0033] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further explained below with reference to specific examples.

[0034] Through thorough research of existing technologies, this invention provides a weather-resistant multispectral selective adjustment film, thereby systematically solving the comprehensive technical problems of existing energy-saving films, such as single function, high haze, and poor weather resistance.

[0035] Therefore, this invention uses doped tungsten bronze nanoparticles (such as chromium-doped cesium tungsten oxide) as near-infrared absorbing nanofillers. The near-infrared absorption mechanism of the doped tungsten bronze nanoparticles is the synergistic effect of localized surface plasmon resonance (LSPR) and small polaron transitions. Specifically, the introduction of cesium (Cs) causes a large number of free carriers to be contained within the [WO6] tunnels. These carriers are confined to the W positions due to lattice energy, generating small polarons in the surrounding lattice. These small polarons then transition between different W positions, absorbing near-infrared light. Simultaneously, free electrons generate localized surface plasmon resonance in the Cs-doped hexagonal tungsten bronze. The small polaron transitions mainly absorb near-infrared light in the 780-1100 nm wavelength range, while the LSPR effect mainly absorbs near-infrared light in the 1500-2500 nm wavelength range. Cr doping allows for further control of carrier concentration and lattice defects, optimizing the intensity ratio of the LSPR effect and small polaron transitions, achieving highly efficient selective absorption of near-infrared light in the 780-2500nm wide wavelength range, thus providing summer heat insulation. It should be noted that under the conditions of high filler content (20-50 parts) and relatively thick adhesive layer (10-25μm) specified in this invention, Cr doping significantly improves the near-infrared blocking rate while slightly affecting visible light transmittance (visible light transmittance decrease ≤5 percentage points). This is a technical trade-off made to achieve a near-infrared blocking rate >90%. This invention uses silane coupling agent surface modification and a three-stage progressive dispersion process to minimize the haze increase during this trade-off (haze <0.6%).

[0036] Simultaneously, high aspect ratio one-dimensional metal nanowires (such as silver nanowires) are interlocked within the adhesive layer. Based on the high-frequency dielectric response of free electron gas (Drude model), they efficiently reflect mid- and far-infrared wavelengths. This effectively reflects 3-50μm mid- and far-infrared electromagnetic waves radiated by indoor objects back into the room, reducing heat loss from the mid- and far-infrared regions during winter and achieving insulation. Furthermore, these two mechanisms act independently in the "absorption" and "reflection" dimensions, with no spectral interference. The ultraviolet absorber selectively absorbs ultraviolet wavelengths with a blocking rate ≥99%, preventing ultraviolet radiation from harming indoor objects and the human body. The synergistic effect of these three components achieves comprehensive blocking of ultraviolet and multi-band infrared radiation.

[0037] Furthermore, to address the problem that nanofillers with different morphologies and surface properties are prone to agglomeration in adhesives, leading to increased haze, this invention introduces a silane coupling agent. The hydrolytic groups in the silane coupling agent molecule hydrolyze to generate silanol groups, which can undergo a condensation reaction with the hydroxyl groups on the surface of chromium-doped cesium oxide to form strong SiO2 chemical bonds, thus grafting the silane coupling agent onto the surface of chromium-doped cesium oxide. The organic groups of the silane coupling agent can interact with the acrylic pressure-sensitive adhesive, reducing the surface energy of chromium-doped cesium oxide, effectively preventing its agglomeration, and improving its dispersion uniformity in the acrylic pressure-sensitive adhesive, thereby ensuring the optical performance (i.e., low haze) and infrared blocking effect of the architectural film.

[0038] Furthermore, this invention abandons the conventional PET substrate and instead uses aliphatic polycarbonate thermoplastic polyurethane (TPU) as the main substrate. Through the aliphatic polycarbonate thermoplastic polyurethane (TPU) substrate and the solvent-based two-component curing layer, excellent anti-yellowing, abrasion resistance, and weather resistance are achieved, making it suitable for outdoor environments and application in the building construction field. Simultaneously, a chemical bonding interface is formed between the TPU substrate and the functional installation adhesive layer through corona treatment, which not only enhances interlayer adhesion but also allows the flexibility of the TPU to buffer the thermal expansion mismatch between the nanoparticles in the functional adhesive layer and the substrate, further improving the long-term stability of the film.

[0039] Based on the above-mentioned core technical mechanism, the present invention designs the following material formulation system: The functional installation adhesive is formed by mixing the following components in the following proportions: Based on 100 parts of acrylic pressure-sensitive adhesive: 2835 parts of solvent, 2050 parts of modified chromium-doped cesium tungsten oxide particles, 46 parts of silver nanowire dispersion, and 0.22 parts of ultraviolet absorber.

[0040] Among them, the acrylic pressure-sensitive adhesive has a solid content of 30%-45%, is compatible with solvent systems, and has good film-forming properties, adhesion and compatibility. It can be used as a carrier for functional fillers to ensure uniform dispersion of each component.

[0041] The solvent contains one or more of ethanol, ethyl acetate, toluene, and butyl acetate, which can fully dissolve and disperse the components and has a moderate evaporation rate, avoiding defects such as pinholes and bubbles in the film.

[0042] As further explanation, the acrylic pressure-sensitive adhesive in this functional mounting adhesive serves as a film-forming matrix and bonding carrier, providing adhesion, dispersion medium, and continuous film-forming properties. The amount of acrylic pressure-sensitive adhesive used is further limited to a solids content range of 30%-45% to achieve a suitable viscosity, effectively carrying and dispersing nanoparticles while forming a continuous and uniform coating. If the solids content is too low, the film thickness after coating will be insufficient, and the adhesion will decrease; if the solids content is too high, the viscosity will be too high, which is not conducive to the uniform dispersion of functional nanoparticles.

[0043] The solvent in this functional mounting adhesive is specifically used to dilute the acrylic pressure-sensitive adhesive, adjust the coating viscosity, promote the dispersion of functional particles in the colloid, and regulate the solvent evaporation rate to avoid coating defects. The preferred amount of solvent in this functional mounting adhesive is 2835 parts by weight. Insufficient solvent (e.g., less than 28 parts) will result in high system viscosity and difficulty in uniform particle dispersion, leading to increased haze; excessive solvent (e.g., more than 35 parts) will result in prolonged coating drying time and insufficient film thickness.

[0044] The modified chromium-doped cesium tungsten oxide particles in this functional mounting adhesive are responsible for efficient absorption in the near-infrared band. The preferred amount of modified chromium-doped cesium tungsten oxide particles in this functional mounting adhesive is 2050 parts by weight. If the amount is less than 20 parts, the near-infrared blocking rate decreases, and if it is more than 50 parts, the visible light transmittance decreases and the haze increases.

[0045] For the modified chromium-doped cesium tungsten oxide particles, this invention employs a dual process of in-situ doping hydrothermal reaction and silane coupling agent surface modification to complete the preparation.

[0046] As further explanation, the preparation process of the corresponding modified chromium-doped cesium oxide tungsten particles is as follows: (1) Preparation of chromium-doped cesium oxide tungsten powder by in-situ doping hydrothermal reaction: (1.1) Dissolve ammonium metatungstate, cesium nitrate, and chromium nitrate in deionized water in a certain proportion and stir continuously, wherein the atomic ratio of tungsten, cesium, and chromium is 1:0.25-0.35:1.5%-2.5%; (1.2) Add citric acid as a mineralizing agent to the mixed solution formed in step (1.1), adjust the pH of the system to 46, place the mixed solution in a high-pressure reactor, and react at 180-200℃ for 10-14 hours. After the reaction is completed, cool to room temperature and then centrifuge, wash and dry. (1.3) After calcination at 450-500℃ in an argon atmosphere for 1.52 h, chromium-doped cesium oxide powder with high crystallinity and good dispersibility is obtained.

[0047] In-situ doping of chromium-doped cesium tungsten oxide powder is employed here, ensuring uniform embedding of chromium within the cesium tungsten oxide lattice, effectively enhancing near-infrared absorption performance, and avoiding problems such as inhomogeneity and performance degradation caused by direct mixing. To further illustrate the Cr doping ratio, the inventors investigated the effect of different Cr / W molar ratios on the optical properties of the thin film through gradient experiments. The results showed that as the Cr / W molar ratio increased from 0.5% to 1.0%, the visible light transmittance gradually increased while the near-infrared blocking rate remained stable; when the Cr / W molar ratio was 1.0%-2.0%, a good balance was achieved between visible light transmittance and near-infrared blocking rate; when the Cr / W molar ratio exceeded 2.5%, the near-infrared blocking rate began to decrease. Therefore, this invention selected a Cr / W range of 1.5%-2.5%, ensuring both an increase in visible light transmittance (8%-12% higher than the undoped sample) and a near-infrared blocking rate >90%.

[0048] (2) Surface modification treatment of silane coupling agent: (2.1) Mix the silane coupling agent and solvent at a mass ratio of 1:5, add hydrochloric acid aqueous solution to adjust the pH to 44.5, and catalyze the hydrolysis of the silane coupling agent; (2.2) According to the ratio of silane coupling agent: chromium-doped cesium oxide powder = 0.04: 0.1: 1, the chromium-doped cesium oxide powder prepared in the previous step was added to the hydrolyzed silane coupling agent solution, and stirred and refluxed at 6570℃ for 6080 min to allow the silane coupling agent to be fully grafted onto the surface of the chromium-doped cesium oxide powder. (2.3) After drying the product formed in step (2.2), the powder is ball-milled to make the particle size D50 < 30 nm, thus obtaining modified chromium-doped cesium oxide particles.

[0049] To further illustrate the grafting amount of the silane coupling agent, the inventors determined the grafting amount under different reaction conditions using thermogravimetric analysis (TGA) and compared the effects of different grafting amounts on dispersibility and haze. The results showed that when the grafting amount was below 4%, the modified particles still exhibited significant agglomeration in the acrylic pressure-sensitive adhesive, with haze > 1.5%; when the grafting amount was 4%-10%, the particles were uniformly dispersed, and the haze could be controlled below 0.6%; when the grafting amount exceeded 10%, the excessive silane coupling agent formed multilayer adsorption on the particle surface, leading to inter-particle bridging and flocculation, and the haze rose back to above 1.0%. Therefore, this invention selected a grafting amount range of 4%-10%.

[0050] As a further explanation, the silane coupling agent used in this preparation step is one or a combination of allyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-(methacryloyloxy)propyltrimethoxysilane. This can effectively improve the dispersibility of chromium-doped cesium oxide tungsten particles, enhance their compatibility with acrylic pressure-sensitive adhesive, avoid the increase in haze caused by particle agglomeration, and at the same time enhance the adhesion and weather resistance of the film layer.

[0051] The nano-silver wire dispersion in this functional mounting adhesive is responsible for efficient reflection in the mid- and far-infrared bands. The preferred amount of nano-silver wire dispersion in this functional mounting adhesive is 46 parts by weight. If the amount is less than 4 parts, the mid- and far-infrared blocking rate will decrease significantly, and if it is more than 6 parts, the haze will increase and the visible light transmittance will decrease.

[0052] The silver nanowire dispersion is specifically prepared from silver nanowires, a solvent, and an acrylic pressure-sensitive adhesive. Specifically, during preparation, the silver nanowires, solvent, and acrylic pressure-sensitive adhesive are mixed in a mass ratio of silver nanowires:solvent:acrylic pressure-sensitive adhesive = 0.1:0.3:2:4, and then sonicated at 2535 kHz for 68 minutes to obtain a uniformly dispersed silver nanowire dispersion.

[0053] In this preparation process, the use of acrylic pressure-sensitive adhesive as a dispersant in advance ensures the compatibility between the silver nanowire dispersion and the functional mounting adhesive layer, avoiding delamination and agglomeration. At the same time, the acrylic pressure-sensitive adhesive can be adsorbed on the surface of the silver nanowire, forming steric hindrance, which further improves the dispersion stability of the silver nanowire and achieves high-efficiency mid- and far-infrared reflection.

[0054] As a further explanation, in this invention, the diameter of the silver nanowires is preferably 3050 nm, and the length is preferably 530 μm. Based on this, as a further preferred configuration, silver nanowires with diameters of 30 nm and 45 nm are combined in a volume ratio of 2:1. This combination method can synergistically enhance the interconnectivity of the conductive network, reduce light scattering, and reduce film haze while ensuring mid- and far-infrared reflectivity.

[0055] The UV absorber in this functional adhesive is responsible for the selective absorption of the ultraviolet band, and the dosage is 0.22 parts by weight. If the dosage is too small (e.g., less than 0.2 parts), the UV blocking effect will be insufficient (e.g., UV blocking rate is less than 99%), and if the dosage is too large (e.g., more than 2 parts), it will affect the visible light transmittance of the film and the film may turn yellow.

[0056] Regarding the above-mentioned functional mounting adhesive formulation system, this invention further provides a preparation process for the functional mounting adhesive.

[0057] This invention, based on the characteristics of each component in the functional mounting adhesive formulation system, employs a "three-stage progressive dispersion" process to prepare the functional mounting adhesive. The specific steps are as follows: First section: Solvent pre-dispersion.

[0058] Add the specified amount of solvent to the acrylic pressure-sensitive adhesive and stir at 200-500 rpm to disperse it evenly. This step dilutes the acrylic pressure-sensitive adhesive, reduces the system viscosity, and creates conditions for the subsequent dispersion of functional particles. A stirring speed of 200-500 rpm is considered low-speed stirring to avoid generating excessive air bubbles; too low a speed results in low dispersion efficiency, while too high a speed easily entangles a large number of air bubbles.

[0059] Second stage: Addition of functional components and medium-speed stirring.

[0060] Modified chromium-doped cesium tungsten oxide particles, silver nanowire dispersion, and ultraviolet absorber are added sequentially, and stirring is continued for 30-40 minutes. This step aims to initially disperse the functional components in the pressure-sensitive adhesive system. The 30-40 minute stirring time is optimized; too short a time will result in insufficient particle dispersion, while too long a time may lead to excessive damage to the silver nanowire network.

[0061] Third stage: Ultrasonic fine dispersion. The above mixture is then ultrasonically dispersed for 10-20 minutes.

[0062] Ultrasonic dispersion uses a high-energy microjets generated by cavitation to break up aggregated nanoparticles, achieving uniform dispersion at the microscale. The ultrasonic time of 10-20 minutes has been optimized; if the time is too short, the aggregates will not be fully opened, while if the time is too long, the silver nanowires may break, reducing the aspect ratio.

[0063] To verify the necessity of the "three-stage progressive dispersion" process, the inventors conducted a comparative experiment: Under the same formulation conditions, omitting the first stage of solvent pre-dispersion (i.e., directly adding functional particles to undiluted acrylic pressure-sensitive adhesive), the resulting slurry showed particle agglomerate size D90 > 500 nm, and the haze of the coated film reached 2.8%; omitting the second stage of medium-speed stirring (i.e., directly performing ultrasonic dispersion after solvent dilution), the resulting slurry showed uneven particle dispersion, with a haze of 1.5%; while using the complete three-stage progressive dispersion process, the particle agglomerate size D90 < 100 nm, and the haze could be controlled below 0.5%. These results demonstrate that the steps of the three-stage progressive dispersion have an irreplaceable sequential order and synergistic effect, and must be performed sequentially to achieve the best dispersion effect.

[0064] In this preparation process, solvent dilution is necessary to reduce viscosity, ensuring smooth dispersion of the functional particles during subsequent stirring. Preliminary dispersion through stirring is essential to provide a foundation for ultrasonic fine dispersion. There is an inverse relationship between stirring speed and stirring time: higher speed requires shorter stirring time, and vice versa. Ultrasonic dispersion time needs to be adjusted based on the dispersion effect of the initial stage; better material dispersion results in shorter ultrasonic time.

[0065] Based on the prepared functional installation adhesive, the present invention further provides a low-haze multi-band barrier architectural film.

[0066] This architectural membrane comprises a PET protective layer, a hardening layer, a TPU substrate, a functional installation adhesive layer, and a release film protective layer, stacked sequentially. The thickness of each layer is precisely controlled to ensure the overall performance and effectiveness of the membrane. The specific thicknesses are as follows: The thickness of the PET protective layer is preferably 40-50 μm, and more preferably 45 μm; The thickness of the hardened layer is preferably 1-4 μm, and more preferably 2 or 3 μm; The thickness of the TPU substrate is preferably 50-80μm, and more preferably 60 or 70μm; The thickness of the functional mounting adhesive layer is preferably 10-25 μm, and more preferably 15 or 20 μm; The thickness of the release film protective layer is preferably 20-25 μm, and more preferably 23 μm.

[0067] In some embodiments, the PET protective layer in the building film formed by the present invention is a highly transparent PET film with good light transmittance, which can provide good protection for the hardened layer and can be directly peeled off during use.

[0068] In some embodiments, the hardened layer in the building membrane formed by the present invention is preferably a solvent-based two-component polyurethane coating, which can significantly improve the surface hardness and abrasion resistance of the building membrane, prevent scratches on the membrane surface, and at the same time have hydrophobicity, providing good stain resistance.

[0069] In some embodiments, the TPU substrate in the architectural film formed by the present invention is preferably aliphatic polycarbonate thermoplastic polyurethane, which has excellent weather resistance, anti-yellowing and flexibility, can adapt to complex outdoor environments, can solve the problem of insufficient weather resistance of traditional PET substrates, and is suitable for the use needs of external building applications. At the same time, it has good light transmittance and does not affect the optical performance of the architectural film.

[0070] In some embodiments, the functional mounting adhesive layer in the architectural membrane formed by the present invention is formed using the functional mounting adhesive provided by the present invention, which can achieve efficient blocking of ultraviolet and multi-band infrared while ensuring low haze and good adhesion; when applied, it can ensure that the architectural membrane can be firmly adhered to the building curtain wall.

[0071] In some embodiments, the release film protective layer in the architectural membrane formed by the present invention can protect the adhesiveness of the functional installation adhesive layer, allowing for direct peeling during use.

[0072] As a further explanation, this invention also provides a corresponding preparation method for this low-haze multi-band blocking architectural film, which includes the following steps: a) Functional mounting adhesive layer coating and lamination: The functional mounting adhesive prepared according to the present invention is uniformly coated on the release film protective layer, and the coating thickness is controlled to be 10-25μm to form a functional mounting adhesive layer; the corona-treated surface of the TPU substrate is bonded to the functional mounting adhesive layer and compacted by a composite equipment to ensure that the two are tightly bonded without bubbles or delamination; the corona treatment can improve the surface roughness and surface energy of the TPU substrate and enhance its adhesion to the functional mounting adhesive layer.

[0073] b) Hardening layer coating and lamination: A solvent-based two-component polyurethane coating is uniformly applied to the other side of the TPU substrate, with the coating thickness controlled at 1-4μm, and the PET protective layer is then bonded to the hardening layer. The resulting low-haze, multi-band barrier architectural membrane has a unique multi-layered structure. The outermost layer is a peelable PET protective layer, which is removed during construction. Below this is a two-component polyurethane hardening layer, providing scratch resistance and stain resistance. The middle layer is an aliphatic TPU substrate layer, providing flexibility and long-term weather resistance. Below that is the core functional layer of this architectural membrane—a multi-spectral selective adjustment installation adhesive layer. The innermost layer is a PET release film, which is peeled off during construction to expose the pressure-sensitive adhesive surface.

[0074] The low-haze multi-band blocking architectural film formed based on the aforementioned formula and process has excellent comprehensive performance: the visible light transmittance can be flexibly adjusted between 40% and 75%, the haze is stably controlled below 0.6%, the ultraviolet blocking rate is ≥99%, the near-infrared blocking rate is ≥90%, and the mid- and far-infrared blocking rate is ≥90%.

[0075] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the following examples are only for providing best practice models of the present invention and should not be construed as limiting the scope of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed according to conventional operating methods and conditions, or according to the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are by weight.

[0076] Performance testing methods: Visible light transmittance and haze: tested according to GB / T 2410-2008 standard; Ultraviolet blocking rate and near-infrared blocking rate: tested according to GB / T 2680-2021 standard using a spectrophotometer (wavelength range 280-2500nm); Mid- and far-infrared blocking rate: Tested according to ASTM E424 standard using a Fourier transform infrared spectrometer (wavelength range 3-50μm); Adhesion: Tested according to GB / T 9286-1998 standard; Weather resistance: In accordance with GB / T 16422.3-2014 standard, a 1500-hour accelerated aging test was conducted using a QUV accelerated aging tester (UVA-340 lamp, irradiance 0.93W / ㎡; UVB-313 lamp, irradiance 0.1W / ㎡), and the degree of yellowing was evaluated by color difference ΔE.

[0077] To further verify the rationality of maintaining ultra-low haze (0.5%) even with high filling amounts (such as 50 parts of modified particles in Example 3), the inventors characterized the dispersibility of the functional mounting adhesive slurries prepared in each example. The particle size distribution and Zeta potential of the particles in the slurry were tested using a dynamic light scattering particle size analyzer. The results showed that: D90 = 95 nm and Zeta potential = -48.2 mV for Example 1; D90 = 88 nm and Zeta potential = -46.5 mV for Example 2; and D90 = 112 nm and Zeta potential = -43.7 mV for Example 3. These data indicate that after modification with a silane coupling agent and three-stage progressive dispersion, the nanoparticles in the slurry did not exhibit significant agglomeration (D90 < 120 nm), and the particle surfaces carried a high negative charge (absolute Zeta potential > 43 mV), generating a strong electrostatic repulsion effect and effectively suppressing the formation of scattering centers. Even under conditions of high filling volume and large thickness, the particles still maintain a highly monodisperse state. Although the scattering optical path increases, the number of scatterers per unit volume does not increase exponentially. Therefore, the haze only increases slightly from 0.3% in Example 2 to 0.5% in Example 3, which is in line with the basic laws of colloidal optics.

[0078] Example 1 This example provides a low-haze multi-band barrier architectural film with the following thicknesses for each layer: PET protective layer 45μm, hardening layer 2μm, TPU substrate 65μm, functional installation adhesive layer 18μm, and release film protective layer 23μm.

[0079] Functional installation adhesive layer components (based on 100 parts of acrylic pressure-sensitive adhesive): 100 parts acrylic pressure-sensitive adhesive (38% solid content), 32 parts solvent (ethanol: ethyl acetate = 3:1), 35 parts modified chromium-doped cesium oxide tungsten particles, 5 parts silver nanowire dispersion, and 1 part ultraviolet absorber.

[0080] The preparation process is as follows: (1) Preparation of modified chromium-doped cesium oxide tungsten particles: Ammonium metatungstate, cesium nitrate, and chromium nitrate were dissolved in deionized water at an atomic ratio of 1:0.3:2% for tungsten, cesium, and chromium, stirred evenly, and citric acid was added as a mineralizing agent to adjust the pH to 5. The mixture was placed in a high-pressure reactor and reacted at 190°C for 12 h. After cooling, the mixture was centrifuged, washed, and dried. It was then calcined at 480°C under an argon atmosphere for 1.8 h to obtain chromium-doped cesium oxide tungsten powder. Allyltrimethoxysilane and solvent (ethanol:ethyl acetate = 3:1) were mixed at a mass ratio of 1:5. Hydrochloric acid aqueous solution was added to adjust the pH to 4.2. After catalytic hydrolysis, the powder was added at a ratio of silane coupling agent: chromium-doped cesium oxide tungsten powder = 0.07:1. The mixture was stirred and refluxed at 68°C for 70 min. After drying, the powder was ball-milled to D50 = 25 nm to obtain modified chromium-doped cesium oxide tungsten particles.

[0081] (2) Preparation of silver nanowire dispersion: Silver nanowires (30nm and 45nm mixed in a volume ratio of 2:1, diameter 3045nm, length 1020μm) were mixed with solvent (ethanol: ethyl acetate = 3:1) and acrylic pressure-sensitive adhesive = 0.2:2:4. The mixture was sonicated at 28kHz for 7min to obtain a uniform silver nanowire dispersion.

[0082] (3) Preparation of functional installation adhesive layer slurry: Add the remaining solvent to the acrylic pressure-sensitive adhesive, stir and disperse evenly at 350 r / min, add the modified chromium-doped cesium oxide tungsten particles, nano silver wire dispersion and ultraviolet absorber in sequence, continue stirring for 35 min, and then ultrasonically disperse for 15 min to obtain the functional installation adhesive layer slurry.

[0083] (4) Film coating: Apply functional mounting adhesive slurry to the release film protective layer, control the thickness to 18μm, and composite it with the corona-treated surface of the TPU substrate (aliphatic polycarbonate thermoplastic polyurethane); apply solvent-based two-component curing layer to the other side of the TPU substrate, control the thickness to 2μm, and composite it with the PET protective layer.

[0084] Performance test results: The visible light transmittance of this building film is 55%, haze is 0.4%, ultraviolet blocking rate is 99.2%, near-infrared blocking rate is 93%, mid- and far-infrared blocking rate is 92%, adhesion reaches level 1 in GB / T 92861998, and after 1500 hours of UV aging (QUVA 340nm 0.93W / ㎡, QUVB 313nm 0.1W / ㎡), the color difference ΔE=1.71, and there are no abnormalities in appearance.

[0085] Example 2 This example provides a low-haze multi-band barrier architectural film with the following thicknesses for each layer: PET protective layer 45μm, hardening layer 1μm, TPU substrate 50μm, functional installation adhesive layer 10μm, and release film protective layer 23μm.

[0086] Functional installation adhesive layer components (based on 100 parts of acrylic pressure-sensitive adhesive): 100 parts acrylic pressure-sensitive adhesive (30% solid content), 28 parts solvent (toluene: butyl acetate = 2:1), 20 parts modified chromium-doped cesium tungsten oxide particles, 4 parts silver nanowire dispersion, and 0.2 parts ultraviolet absorber.

[0087] The preparation process is as follows: (1) Preparation of modified chromium-doped cesium oxide tungsten particles: Ammonium metatungstate, cesium nitrate, and chromium nitrate were dissolved in deionized water at an atomic ratio of 1:0.25:1.5% for tungsten, cesium, and chromium, stirred evenly, and citric acid was added as a mineralizing agent to adjust the pH to 4. The mixture was placed in a high-pressure reactor and reacted at 180°C for 14 h. After cooling, the mixture was centrifuged, washed, and dried. It was then calcined at 450°C under an argon atmosphere for 2 h to obtain chromium-doped cesium oxide tungsten powder. γ-glycidyl etheroxypropyltrimethoxysilane and solvent (toluene: butyl acetate = 2:1) were mixed at a mass ratio of 1:5. Hydrochloric acid aqueous solution was added to adjust the pH to 4.0. After catalytic hydrolysis, the powder was added at a ratio of silane coupling agent: chromium-doped cesium oxide tungsten powder = 0.04:1. The mixture was stirred and refluxed at 65°C for 60 min. After drying, it was ball-milled to D50 = 28 nm to obtain modified chromium-doped cesium oxide tungsten particles.

[0088] (2) Preparation of silver nanowire dispersion: Silver nanowires (30nm and 45nm mixed in a volume ratio of 2:1, diameter 3045nm, length 515μm) were mixed with solvent (toluene: butyl acetate = 2:1) and acrylic pressure-sensitive adhesive = 0.1:2:4. The mixture was sonicated at 25kHz for 6min to obtain a uniform silver nanowire dispersion.

[0089] (3) Preparation of functional installation adhesive layer slurry: Add the remaining solvent to the acrylic pressure-sensitive adhesive, stir and disperse evenly at 200 r / min, add the modified chromium-doped cesium oxide tungsten particles, nano-silver wire dispersion and ultraviolet absorber in sequence, continue stirring for 30 min, and then ultrasonically disperse for 10 min to obtain the functional installation adhesive layer slurry.

[0090] (4) Film coating: Apply functional mounting adhesive slurry to the release film protective layer, control the thickness to 10μm, and composite it with the corona-treated surface of the TPU substrate (aliphatic polycarbonate thermoplastic polyurethane); apply solvent-based two-component curing layer to the other side of the TPU substrate, control the thickness to 1μm, and composite it with the PET protective layer.

[0091] Performance test results: The visible light transmittance of this building film is 70%, haze is 0.3%, ultraviolet blocking rate is 99.0%, near-infrared blocking rate is 90%, mid- and far-infrared blocking rate is 90%, adhesion reaches level 1, color difference ΔE=1.92 after 1500 hours of UV aging, and there are no abnormalities in appearance.

[0092] Example 3 This example provides a low-haze multi-band barrier architectural film with the following thicknesses for each layer: PET protective layer 45μm, hardening layer 4μm, TPU substrate 80μm, functional installation adhesive layer 25μm, and release film protective layer 23μm.

[0093] Functional installation adhesive layer components (based on 100 parts of acrylic pressure-sensitive adhesive): 100 parts acrylic pressure-sensitive adhesive (45% solid content), 35 parts solvent (ethanol:toluene:ethyl acetate = 2:1:1), 50 parts modified chromium-doped cesium oxide tungsten particles, 6 parts silver nanowire dispersion, and 2 parts ultraviolet absorber.

[0094] The preparation process is as follows: (1) Preparation of modified chromium-doped cesium oxide tungsten particles: Ammonium metatungstate, cesium nitrate, and chromium nitrate were dissolved in deionized water at an atomic ratio of 1:0.35:2.5% for tungsten, cesium, and chromium, stirred evenly, and citric acid was added as a mineralizing agent to adjust the pH to 6. The mixture was placed in a high-pressure reactor and reacted at 200°C for 10 h. After cooling, the mixture was centrifuged, washed, and dried. It was then calcined at 500°C under an argon atmosphere for 1.5 h to obtain chromium-doped cesium oxide tungsten powder. γ-(methacryloyloxy)propyltrimethoxysilane was mixed with a solvent (ethanol:toluene:ethyl acetate = 2:1:1) at a mass ratio of 1:5. Hydrochloric acid aqueous solution was added to adjust the pH to 4.5. After catalytic hydrolysis, the powder was added at a ratio of silane coupling agent: chromium-doped cesium oxide tungsten powder = 0.1:1. The mixture was stirred and refluxed at 70°C for 80 min. After drying, it was ball-milled to D50 = 22 nm to obtain modified chromium-doped cesium oxide tungsten particles.

[0095] (2) Preparation of silver nanowire dispersion: Silver nanowires (30nm and 45nm mixed in a volume ratio of 2:1, diameter 3045nm, length 2030μm) were mixed with solvent (ethanol:toluene:ethyl acetate = 2:1:1) and acrylic pressure-sensitive adhesive = 0.3:2:4. The mixture was ultrasonicated at 35kHz for 8min to obtain a uniform silver nanowire dispersion.

[0096] (3) Preparation of functional installation adhesive layer slurry: Add the remaining solvent to the acrylic pressure-sensitive adhesive, stir and disperse evenly at 500 r / min, add the modified chromium-doped cesium oxide tungsten particles, nano silver wire dispersion and ultraviolet absorber in sequence, continue stirring for 40 min, and then ultrasonically disperse for 20 min to obtain the functional installation adhesive layer slurry.

[0097] (4) Film coating: Apply functional mounting adhesive slurry to the release film protective layer, control the thickness to 25μm, and composite it with the corona-treated surface of the TPU substrate (aliphatic polycarbonate thermoplastic polyurethane); apply solvent-based two-component curing layer to the other side of the TPU substrate, control the thickness to 4μm, and composite it with the PET protective layer.

[0098] Performance test results: The visible light transmittance of this building film is 40%, haze is 0.5%, ultraviolet blocking rate is 99.5%, near-infrared blocking rate is 95%, mid- and far-infrared blocking rate is 94%, adhesion reaches level 1, color difference ΔE=2.08 after 1500 hours of UV aging, and there are no abnormalities in appearance.

[0099] Comparative Example 1 (Silane Coupling Agent-Free Modification) This example provides a building membrane, which differs from Example 1 in that no silane coupling agent is added (i.e., no silane coupling agent surface modification is performed during the preparation of modified chromium-doped cesium oxide tungsten particles), while the remaining components and preparation methods are the same.

[0100] Performance test results: The haze of the building membrane was 3.7%, the visible light transmittance was 53%, the ultraviolet light blocking rate was 99.2%, the near-infrared blocking rate was 79%, the mid- and far-infrared blocking rate was 82%, and the adhesion was grade 3. Because the sample showed obvious film peeling and discoloration after 500 hours of QUV accelerated aging testing, indicating damage to its physical structure, the aging test was terminated, and data collection for 1500 hours was not continued (the corresponding position in Table 1 is marked "Film failure at 500h, test terminated"). This demonstrates that the silane coupling agent plays a crucial role in improving the dispersibility of nanoparticles.

[0101] Comparative Example 2 (without silver nanowires) This example provides a building membrane that differs from Example 1 in that it does not contain a dispersion of silver nanowires, while the other components and preparation methods are the same.

[0102] Performance test results: The building membrane has a haze of 0.4%, visible light transmittance of 64%, ultraviolet light blocking rate of 99.3%, near-infrared light blocking rate of 93%, and mid- and far-infrared light blocking rate of only 37%. Adhesion is rated at level 1. After 1500 hours of UV aging, the color difference ΔE = 1.66, and there are no abnormalities in appearance. This demonstrates the crucial role of nano-silver wires in mid- and far-infrared reflection; without nano-silver wires, winter insulation effects cannot be achieved.

[0103] Comparative Example 3 (No Cr Doping) This example provides a building membrane, which differs from Example 1 in that it uses undoped cesium tungsten oxide instead of chromium-doped cesium tungsten oxide (i.e., cesium tungsten oxide is synthesized at a W:Cs atomic ratio of 1:0.3 without adding chromium nitrate), while the other components and preparation methods are the same.

[0104] Performance test results: The building membrane has a haze of 0.5%, visible light transmittance of 60%, ultraviolet light blocking rate of 99.2%, near-infrared light blocking rate of 82%, and mid- and far-infrared light blocking rate of 90%. After 1500 hours of UV aging, the color difference ΔE = 1.54, and there are no abnormalities in appearance. This indicates the importance of Cr doping in improving near-infrared blocking performance; the near-infrared blocking rate is significantly reduced when undoped.

[0105] Comparative Example 4 (Non-in-situ doping) This example provides a building membrane, which differs from Example 1 in that the chromium-doped cesium tungsten oxide is prepared by directly mixing chromium nitrate and cesium tungsten oxide (i.e., first synthesizing cesium tungsten oxide powder, then physically mixing it with chromium nitrate, and then modifying it with a silane coupling agent). The other components and preparation methods are the same.

[0106] Performance test results: The building membrane has a haze of 1.8%, visible light transmittance of 61%, ultraviolet light blocking rate of 99.1%, near-infrared blocking rate of 77%, and mid- and far-infrared blocking rate of 88%. After 1500 hours of UV aging, the color difference ΔE = 2.31, with slight discoloration. This indicates that the direct mixing method can only adsorb Cr3+ onto the particle surface and cannot penetrate into the crystal lattice, thus failing to achieve true lattice doping. The near-infrared blocking rate is far lower than that of the in-situ doping method.

[0107] Comparative Example 5 (no TPU substrate, using PET substrate) This example provides a building membrane, which differs from Example 1 in that a PET substrate is used instead of a TPU substrate, while the other components and preparation methods are the same.

[0108] Performance test results: The building film has a haze of 0.5%, visible light transmittance of 56%, ultraviolet blocking rate of 99.2%, near-infrared blocking rate of 92%, mid- and far-infrared blocking rate of 91%, and adhesion rating of Grade 1. However, after 1500 hours of UV aging, the color difference ΔE=4.52, and the appearance becomes yellow and brittle. This indicates the crucial role of TPU substrate in the weather resistance of surface-mount applications, and that PET substrate cannot meet the requirements for long-term surface-mount use.

[0109] Comparative Example 6 (Verification of Overall Synergistic Effect: Not the Complete Solution of This Invention) This example provides a building membrane in which the components of Example 1 are simply mixed (i.e., instead of using a three-stage progressive dispersion process, all components are added at once and stirred for 60 minutes), and the remaining components and preparation methods are the same.

[0110] Performance test results: The building membrane has a haze of 2.1%, visible light transmittance of 51%, ultraviolet light blocking rate of 99.0%, near-infrared blocking rate of 81%, and mid- and far-infrared blocking rate of 79%. After 1500 hours of UV aging, the color difference ΔE = 2.89, and slight particle precipitation is observed. Compared with Example 1, all performance characteristics are significantly deteriorated, indicating that the specific formulation of this invention requires a synergistic relationship with the three-stage progressive dispersion process; the comprehensive performance of this invention cannot be achieved simply by adding components together.

[0111] Commercially available PET type architectural insulation film As a control, commercially available typical PET-based architectural insulation films were selected for performance testing under the same conditions.

[0112] Performance test results: The haze of this commercially available PET building insulation film is 0.7%, the visible light transmittance is 72%, the ultraviolet blocking rate is 99.5%, the near-infrared blocking rate is 85%, the mid- and far-infrared blocking rate is 60%, and the color difference ΔE=4.18 after 1500 hours of UV aging, and the appearance is yellowed and loses its luster.

[0113] Overall synergistic effect verification experiment To further verify the synergistic effect among the various technical features of this invention, the inventors designed the following comparative experiment: (1) Only Cr-doped cesium tungsten oxide (without silver nanowires or TPU substrate): near-infrared blocking rate of 93%, mid-far-infrared blocking rate of only 35%, visible light transmittance of 58%, haze of 0.4%, UV aging ΔE=3.85; (2) Only silver nanowires added (no Cr-doped cesium tungsten oxide, no TPU substrate): mid- and far-infrared blocking rate of 92%, near-infrared blocking rate of only 45%, visible light transmittance of 70%, haze of 0.5%, UV aging ΔE=3.92; (3) Simultaneous addition of Cr-doped cesium tungsten oxide and silver nanowires (with TPU substrate, but without silane coupling agent modification): near-infrared blocking rate 79%, mid-far-infrared blocking rate 82%, haze 3.7%, film failure occurs after 500h of UV aging. (4) Simultaneous addition of Cr-doped cesium tungsten oxide and silver nanowires (modified with silane coupling agent and TPU substrate, but not in-situ doped): near-infrared blocking rate 77%, mid-far-infrared blocking rate 88%, haze 1.8%, UV aging ΔE=2.31; (5) Complete solution of the present invention (Example 1): Near-infrared blocking rate 93%, mid-far-infrared blocking rate 92%, haze 0.4%, UV aging ΔE=1.71.

[0114] The comparative experiments above show that adding Cr-doped cesium tungsten oxide or silver nanowires alone only achieves infrared blocking in a single band; adding both simultaneously without silane coupling agent modification achieves dual-band blocking but results in a sharp increase in haze (3.7%); adding both simultaneously and introducing silane coupling agent modification but using an in-situ doping process still results in unsatisfactory near-infrared blocking (77%); only by using the complete scheme of this invention (in-situ Cr doping + silane coupling agent modification + silver nanowire compound + TPU substrate + three-stage progressive dispersion) can the comprehensive performance of near-infrared blocking >90%, mid- and far-infrared blocking >90%, haze <0.6%, and excellent weather resistance be simultaneously achieved. These results fully demonstrate the significant synergistic effect among the various technical features of this invention, and its comprehensive performance far exceeds the simple summation of the individual contributions of each feature.

[0115] A comprehensive performance comparison between the above embodiments and comparative examples is shown in Table 1: Table 1

[0116] Note: The UV aging test conditions are QUVA (340nm) 0.93W / ㎡, QUVB (313nm) 0.1W / ㎡, and the test duration is 1500 hours.

[0117] Comprehensive performance analysis The above embodiments and comparative examples show that the present invention effectively improves the dispersibility of chromium-doped cesium tungsten oxide by modifying it with a silane coupling agent, and achieves multi-band infrared blocking by combining it with silver nanowires. Furthermore, the chromium-doped cesium tungsten oxide is prepared using an in-situ doping process, avoiding doping failure caused by directly mixing chromium nitrate and cesium tungsten oxide. Acrylic pressure-sensitive adhesive is used as the carrier for the functional installation adhesive layer, in conjunction with a TPU substrate and a hardening layer, so that the building film has low haze, high light transmittance, high weather resistance and excellent adhesion.

[0118] Example 13 simultaneously achieved ultraviolet (≥99%), near-infrared (≥90%), and mid-to-far-infrared (≥90%) blocking, while commercially available PET-type building insulation films only achieved 60% mid-to-far-infrared blocking, Comparative Example 2 (without silver nanowires) only achieved 37% mid-to-far-infrared blocking, and Comparative Example 3 (without Cr doping) only achieved 82% near-infrared blocking. This indicates that only a synergistic system possessing all three functional components can achieve full-spectrum energy saving.

[0119] The haze of Examples 13 was between 0.3% and 0.5%, while the haze of Comparative Example 1 (without silane coupling agent modification) was as high as 3.7%, and the haze of Comparative Example 4 (non-in-situ doping) was 1.8%. This demonstrates that surface modification and in-situ doping of silane coupling agents are necessary technical means to reduce haze, and the synergistic effect of the two can control the haze below 0.5%.

[0120] In Example 13, after 1500 hours of accelerated aging, the ΔE value was less than 2.1, and there were no abnormalities in appearance. In contrast, Comparative Example 1 and the commercially available PET film showed obvious yellowing, discoloration, or peeling after UV aging. Comparative Example 5 (PET substrate) showed ΔE=4.52 after 1500 hours of UV aging, exhibiting yellowing and embrittlement. This demonstrates that the combination of aliphatic polycarbonate TPU substrate and solvent-based two-component curing layer achieves surface-mount-grade weather resistance.

[0121] Comparative Example 4, prepared using a direct mixing method, achieved a near-infrared blocking rate of only 77%, significantly inferior to the 93% of Example 1. This demonstrates that the effective embedding of Cr into the crystal lattice has a significant impact on near-infrared absorption performance. Simultaneously, while the haze of Comparative Example 4 (1.8%) was higher than that of Example 1 (0.4%), it was significantly better than that of Comparative Example 1 (3.7%). This further indicates that the contribution of silane coupling agent modification to haze reduction (3.7% → 1.8%) is greater than the impact of doping method (in-situ vs. non-in-situ) on haze (1.8% → 0.4%). This invention comprehensively achieves the synergistic goal of near-infrared blocking rate >90% and haze <0.6% through a combination of techniques primarily based on "silane coupling agent modification + three-stage dispersion" and supplemented by "in-situ doping".

[0122] Comparative Example 6, which simply mixed all components (without employing the three-stage progressive dispersion process), resulted in a haze as high as 2.1%, a near-infrared blocking rate of only 81%, and a mid-to-far-infrared blocking rate of only 79%, all significantly inferior to Example 1. This demonstrates that the three-stage progressive dispersion process is not a simple superposition of steps, but rather possesses an irreplaceable sequential order and synergistic effect.

[0123] In summary, the technical solution of this invention achieves a balance between high-efficiency blocking and low haze across the ultraviolet, near-infrared, mid- and far-infrared bands through the organic combination of three core technologies: a functional particle system based on "silane coupling agent modification + three-stage dispersion" and supplemented by "in-situ Cr doping," a nano-silver wire system based on "compounding + pre-dispersion," and a preparation process based on "three-stage progressive dispersion." Furthermore, the interfacial synergy between the TPU substrate and the functional adhesive layer ensures weather resistance suitable for external applications. This represents a significant and innovative technological advancement in the field of building energy-saving films.

[0124] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A low-haze multi-band barrier architectural membrane, characterized in that, The architectural membrane comprises a PET protective layer, a hardening layer, a TPU substrate, a functional installation adhesive layer, and a release film protective layer, which are stacked sequentially. The functional mounting adhesive layer comprises acrylic pressure-sensitive adhesive, near-infrared absorbing functional particles, mid- and far-infrared reflective functional particles, ultraviolet absorber, and solvent; The near-infrared absorbing functional particles are cesium tungsten oxide nanoparticles modified with metal elements, and the mid- and far-infrared reflecting functional particles are nano-metal wires.

2. The low-haze multi-band barrier architectural membrane according to claim 1, characterized in that, The TPU substrate is an aliphatic polycarbonate thermoplastic polyurethane with a thickness of 50-80 μm.

3. The low-haze multi-band barrier architectural membrane according to claim 1, characterized in that, The hardened layer is a solvent-based two-component polyurethane coating with a thickness of 1-4 μm.

4. The low-haze multi-band barrier architectural membrane according to claim 1, characterized in that, The functional mounting adhesive layer comprises, based on 100 parts by weight of acrylic pressure-sensitive adhesive, 28-35 parts by weight of solvent, 20-50 parts by weight of near-infrared absorbing functional particles, 4-6 parts by weight of mid- and far-infrared reflective functional particle dispersion, and 0.2-2 parts by weight of ultraviolet absorber.

5. The low-haze multi-band barrier architectural membrane according to claim 1, characterized in that, In the cesium oxide tungsten nanoparticles modified with metal elements, the metal element is selected from at least one of chromium, iron, cobalt, nickel, and manganese, and the atomic ratio of tungsten, cesium, and the metal element in the cesium oxide tungsten is 1:0.25-0.35:0.015-0.

025.

6. The low-haze multi-band barrier architectural membrane according to claim 1, characterized in that, The near-infrared absorbing functional particles are chromium-doped cesium oxide nanoparticles modified with a silane coupling agent, and the grafting amount of the silane coupling agent is 4-10% of the mass of the chromium-doped cesium oxide.

7. The low-haze multi-band barrier architectural membrane according to claim 6, characterized in that, The silane coupling agent is selected from one or more combinations of allyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-(methacryloyloxy)propyltrimethoxysilane.

8. The low-haze multi-band barrier architectural membrane according to claim 1, characterized in that, The diameter of the nanowire is 30-50 nm and the length is 5-30 μm, and it is selected from at least one of silver nanowires, gold nanowires, and copper nanowires.

9. The low-haze multi-band barrier architectural membrane according to claim 8, characterized in that, The nanowires are composed of silver nanowires with diameters of 30 nm and 45 nm in a volume ratio of 2:

1.

10. A method for preparing a low-haze multi-band barrier architectural film according to any one of claims 1 to 9, characterized in that, Includes the following steps: A functional mounting adhesive slurry is coated on the release film protective layer to form a functional mounting adhesive layer with a thickness controlled at 10-25μm, which is then bonded to the corona-treated surface of the TPU substrate. A hardening layer slurry is coated on the other side of the TPU substrate to form a hardened layer with a thickness of 1-4μm, which is then laminated with a PET protective layer.

11. The method for preparing a low-haze multi-band barrier architectural film according to claim 10, characterized in that, It also includes the preparation steps of the functional installation adhesive layer slurry, including: Add the solvent to the acrylic pressure-sensitive adhesive and stir at 200-500 r / min to disperse it evenly; Add near-infrared absorbing functional particles, mid- and far-infrared reflective functional particle dispersion and ultraviolet absorber in sequence, and continue stirring for 30-40 minutes; After ultrasonic dispersion for 10-20 minutes, the functional installation adhesive layer slurry is obtained.

12. The preparation method according to claim 11, characterized in that, In the functional installation adhesive slurry, the mid- and far-infrared reflective functional particle dispersion is prepared in advance by mixing nano-metal wires, solvents and acrylic pressure-sensitive adhesives at a mass ratio of 0.1-0.3:2:4 and then sonicating at 25-35 kHz for 6-8 minutes.

13. The preparation method according to claim 11, characterized in that, The near-infrared absorbing functional particles are prepared through in-situ doping hydrothermal reaction and surface modification with silane coupling agent, specifically including: Tungsten source, cesium source and metal dopant source are dissolved in deionized water according to the metal atomic ratio, mineralizing agent is added, pH is adjusted to 4-6, hydrothermal reaction is carried out at 180-200℃ for 10-14h, and then calcined at 450-500℃ in an inert atmosphere for 1.5-2h to obtain metal-doped cesium tungsten oxide powder. The surface of the metal-doped cesium oxide tungsten powder was modified using a silane coupling agent, and then ball-milled until D50 < 30 nm after drying.

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