Composite functional film with high light transmission and UV (ultraviolet) filtering property

Abstract

The invention relates to the technical field of functional films, and discloses a composite functional film with high light transmission and UV (ultraviolet) filtering property, which sequentially comprises a base material layer, a bonding layer, a dual-mechanism UV filtering functional layer, a superhard layer and a surface functional layer from bottom to top, the bonding layer is a Cr or Ti layer; the dual-mechanism UV filtering functional layer comprises a disordered multilayer dielectric film and a plasma resonance enhanced absorption layer; the superhard layer is of a three-dimensional interpenetrating network structure formed by a diamond-like carbon phase and hexagonal boron nitride nanosheets; the surface functional layer is a photocatalytic surface functional layer, and the photocatalytic surface functional layer is a TiO2 / SiO2 composite material with a micro-nano hierarchical porous structure. The composite functional film provided by the invention realizes high UV barrier and high light transmission balance, improves the mechanical durability of the film body, and is applicable to multiple scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional film, in particular to a composite functional film with high light transmittance and UV ultraviolet light filtering property. BACKGROUND

[0002] With the rapid development of display technology, aerospace, cultural heritage protection and high-end construction fields, increasingly stringent requirements are put forward for functional transparent films used for surface protection. Among them, how to effectively isolate ultraviolet light (UV, wavelength 200-400 nm) in sunlight while maintaining extremely high visible light transmittance has become a key technical challenge. Ultraviolet light, especially UVA (315-400 nm) and UVB (280-315 nm) bands, has high photon energy. Under long-term or strong irradiation, it can cause serious damage to materials: In the display field: polarizing films, liquid crystals, optical adhesives (OCA), color filters, organic light-emitting diode (OLED) light-emitting layers, and plastic light guide plates inside display devices, etc. Organic materials will undergo photo-oxidative degradation reactions under the action of ultraviolet light, resulting in yellowing, embrittlement, and performance degradation of materials. Specific manifestations are: screen brightness decreases, color deviation (such as yellowing), color saturation decreases, residual images appear, even delamination, bubbles are generated, etc., which seriously shortens the service life of the device and affects the visual experience.

[0003] In the aerospace and transportation fields: spacecraft portholes, aircraft suspended windows, automobile windshields, etc. are exposed to high-intensity ultraviolet radiation for a long time, and their polymer interlayers, sealants, etc. are prone to aging, which threatens safety and transparency.

[0004] In the field of cultural heritage protection: ultraviolet light is the main culprit of the fading and aging of organic cultural relics such as textiles, paper, pigments, etc.

[0005] To cope with the harm caused by ultraviolet light, the existing technology mainly develops the following schemes, but they all have their own limitations: The first type: organic ultraviolet light absorber additive type film Such technology directly blends organic UV absorbers (e.g. benzotriazoles, benzophenones) into polymer substrates (e.g. PET, PC) or coatings. This method is simple and low cost, and is currently the most widely used solution. However, it has inherent drawbacks, including: poor durability: organic absorber molecules gradually photochemically decompose and lose their effectiveness after absorbing UV energy, i.e. there is a "photobleaching" phenomenon, resulting in a sharp decline in UV protection function over time. High load and transparency conflict: to achieve high UV blocking rate, a large amount of absorber is often added, which can easily cause visible light scattering, resulting in increased haze and decreased light transmittance of the film, and even a yellow tint, affecting the visual effect. Potential migration: some small molecule absorbers may migrate out of the substrate, affecting long-term stability.

[0006] Second type: inorganic nanoparticle dispersion type film Nanoscale inorganic UV shielding agents such as titanium dioxide (TiO2) and zinc oxide (ZnO) are dispersed in resins to form films. Compared with organic absorbers, inorganic particles have better chemical stability and durability. However, the technical bottleneck is: photocatalytic activity problem: especially anatase TiO2, under UV light, it can produce strong oxidizing hole-electron pairs, which can catalyze the degradation of the surrounding polymer matrix, accelerating the overall aging of the film (i.e. "powdering" phenomenon). Although surface coating of ZnO and other materials can alleviate this problem, it increases the complexity and cost of the process. Nanoparticle dispersion problem: nanoparticles are prone to agglomeration to form secondary particles, causing severe visible light scattering, reducing light transmittance and increasing haze.

[0007] Third type: medium multilayer film based on optical interference principle This technology alternately deposits high and low refractive index materials on the substrate by vacuum coating (e.g. magnetron sputtering, electron beam evaporation), and uses the interference effect of light to reflect specific wavelengths of UV light by designing the thickness of the film layers. The advantages of this method are that the film layers are all inorganic, have excellent durability, and can achieve high visible light transmission (anti-reflection effect) by design. However, the significant disadvantages are: angle sensitivity: the center wavelength of the reflection band will shift towards the short wave direction (blue shift) as the light incidence angle increases. This means that at large angles of incidence, the UV light that was originally reflected may be transmitted, making the protection effect unstable. Bandwidth limitation: to achieve high reflection in a wide wavelength range (e.g. covering UVA and UVB), a large number of film layers are usually required, resulting in long preparation period, high cost, and high internal stress, affecting the firmness of the film layers. "Edge" effect: in the transition area at the edge of the reflection band, the blocking rate may not be ideal.

[0008] Fourth type: difficulty in balancing function and performance In addition, high-end applications not only require UV protection and high light transmission, but also often require the film to have high hardness (anti-scratch), wear resistance, hydrophobic and oleophobic (anti-fingerprint), and even self-cleaning functions. The existing technology mostly adopts the method of stacking different functional film layers one by one, but the matching (such as adhesion, thermal expansion coefficient, internal stress) between layers is a prominent problem, and the complex structure also increases the process difficulty and failure risk. It is difficult to achieve perfect balance and long-term maintenance of multiple high performance in a single film system.

[0009] In summary, a new technical solution is needed to overcome the various defects of the prior art and achieve the comprehensive goal of ultrahigh and stable ultraviolet blocking rate, extremely high visible light transmittance, excellent mechanical durability, and long-term surface functionality. SUMMARY

[0010] In view of this, the present application proposes a composite functional film with high light transmittance and UV ultraviolet light filtering, aiming to solve at least one of the problems in the above background art.

[0011] The present application proposes a composite functional film with high light transmittance and UV ultraviolet light filtering, which comprises from bottom to top: a substrate layer, a bonding layer, a dual-mechanism UV filtering functional layer, a superhard layer, and a surface functional layer; The bonding layer is a Cr or Ti layer; The dual-mechanism UV filtering functional layer includes an unordered multilayer dielectric film and a plasmonic resonance enhanced absorption layer; The superhard layer is a three-dimensional interpenetrating network structure formed by diamond-like carbon phase and hexagonal boron nitride nanosheet; The surface functional layer is a photocatalytic type surface functional layer, which is a TiO2 / SiO2 composite material with micro-nano hierarchical porous structure.

[0012] Preferably, the unordered multilayer dielectric film includes a high refractive index layer and a low refractive index layer, the material of the high refractive index layer is Ta2O5 or HfO2, and the material of the low refractive index layer is SiO2, the physical thickness of each layer is randomly distributed between λ / 8n and λ / 2n, where λ is a random wavelength in the range of 250nm to 420nm, and n is the refractive index of the corresponding layer material.

[0013] Preferably, the plasmonic resonance enhanced absorption layer includes noble metal nanoparticles, semiconductor quantum dots and dielectric matrix, the noble metal nanoparticles are silver nano-triangular plates or gold nanorods, the semiconductor quantum dots are ZnO or CsPbBr3 quantum dots, and the dielectric matrix is Al2O3 or SiO2, the total thickness of this layer is 30-80nm.

[0014] Preferably, the volume ratio of diamond-like carbon phase to hexagonal boron nitride nanosheet in the superhard layer is 1:1 to 3:1, and the layer thickness of the superhard layer is 50-200 nm.

[0015] Preferably, the photocatalytic surface functional layer is specifically a three-dimensional macroporous framework formed by stacking mesoporous SiO2 balls, and the inner wall of the pores is loaded with anatase TiO2 nanocrystals.

[0016] Preferably, a stress buffer layer with a refractive index of 1.6-1.8 is arranged between the dual-mechanism UV filtering functional layer and the superhard layer.

[0017] The application also provides a preparation method of the composite functional film, comprising the following steps: Substrate pretreatment: ultrasonic cleaning and ion beam bombardment activation of the substrate; Deposition of the bonding layer: depositing a Cr or Ti layer with a thickness of 2-20 nm by direct current magnetron sputtering; Deposition of the dual-mechanism UV filtering functional layer: using high-power pulse magnetron sputtering technology, non-periodically alternating deposition of high-refractive-index layers and low-refractive-index layers by real-time changing of sputtering power and deposition time to form the disordered multilayer dielectric film; Growth of the plasmonic resonance enhanced absorption layer: using plasma enhanced chemical vapor deposition, co-depositing metal organic precursors and semiconductor precursors in an inert gas and reaction gas atmosphere; Deposition of the superhard layer: using double-target co-sputtering combined with ion beam assisted deposition technology, simultaneously sputtering a graphite target and a hexagonal boron nitride target to form an interpenetrating network structure of diamond-like carbon phase and hexagonal boron nitride nanosheet under substrate bias and ion bombardment; Deposition of the surface functional layer: using sol-gel spin coating combined with hydrothermal crystallization treatment, first forming a SiO2 microsphere template, then introducing a titanium source for hydrothermal reaction, and finally obtaining an anatase TiO2 / SiO2 composite photocatalytic layer through annealing treatment.

[0018] Preferably, the pulse frequency of the high-power pulse magnetron sputtering technology is 100-500 Hz, the duty cycle is 50%-90%, and the substrate table temperature is 200-300 DEG C.

[0019] Preferably, the metal organic precursor for growing the plasmonic resonance enhanced absorption layer is trimethylaluminum or tetraethyl orthosilicate, the semiconductor precursor is a diethyl zinc hexane solution, and the plasma power is 200-500 W.

[0020] The application also provides application of the composite functional film in preparation of a space station porthole, a high-end military display device or a long-term protective cover for precious cultural relics outdoors.

[0021] Compared with the prior art, the present application has the beneficial effects that: (1) Achieving high UV blocking and high light transmission balance: The double-mechanism UV filtering functional layer can efficiently block 250-420 nm full-band UV with excellent blocking rate, and the design of each layer is adapted to optical performance, with high visible light transmittance, avoiding color deviation or light transmission loss, solving the problem of difficult balance between blocking and light transmission of traditional films.

[0022] (2) Improving the mechanical durability of the film body: The super-hard layer has high hardness and strong wear resistance, can resist scratching and collision, and protect the underlying functional layer; the interlayer (Cr / Ti) enhances the interlayer adhesion to avoid interlayer peeling, and is suitable for complex use environments such as aerospace and outdoor. In addition, the anatase TiO2 of the surface functional layer (TiO2 / SiO2 micro-nano porous structure) can photocatalytically decompose organic pollutants, the porous structure improves the reaction efficiency, reduces manual cleaning, and the refractive index of SiO2 and TiO2 is adapted, without affecting the light transmittance.

[0023] (3) Adapting to multiple scene requirements: The substrate layer of the present application can be selected from quartz glass (extreme environment resistant), chemically strengthened aluminosilicate glass (anti-creation durable), polycarbonate (lightweight), combined with the characteristics of each functional layer, and can be used in different high-end scenes such as space station porthole, military display, cultural relic protection, etc. DETAILED DESCRIPTION

[0024] The various illustrative embodiments of the present application will now be described in detail in connection with the following figures. This description is not to be considered limiting in scope, but rather as merely one description of certain aspects of the present application. It is understood that the use of certain specific language makes it possible that not all aspects of the present application are covered by each statement made. It is further understood that the present application includes all products of the manufacture (articles of manufacture) that can be made by a process of the present application, regardless of whether the final product is expressly claimed.

[0025] In addition, for numerical ranges in the present application, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or intervening value in any stated range, and any other stated value or intervening value in that stated range, is also encompassed within the application. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In the case of conflict between any document incorporated by reference and the present specification, the present specification will control.

[0027] Many modifications and variations to the illustrative embodiments described herein will be apparent to those skilled in the art from consideration of the specification and practice of the subject technology. Additional embodiments of the technology will be apparent to those skilled in the art from consideration of the specification and practice of the subject technology. The specification and examples provided should be considered exemplary only.

[0028] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean including, but not limited to.

[0029] The present application provides a composite functional film with high light transmittance and UV ultraviolet light filtering function, which comprises from bottom to top: a substrate layer, a bonding layer, a dual-mechanism UV filtering functional layer, a superhard layer and a surface functional layer; The bonding layer is a Cr or Ti layer; The dual-mechanism UV filtering functional layer comprises a disordered multilayer dielectric film and a plasmonic resonance enhanced absorption layer; The superhard layer is a three-dimensional interpenetrating network structure formed by diamond-like carbon phase and hexagonal boron nitride nanosheet; The surface functional layer is a photocatalytic type surface functional layer, which is a TiO2 / SiO2 composite material with micro-nano hierarchical porous structure.

[0030] The substrate layer of the present application is preferably quartz glass, chemically strengthened aluminosilicate glass or polycarbonate, which has high light transmittance, wherein the visible light transmittance of quartz glass is ≥93%, the temperature resistance range is -200~1200℃, the radiation resistance dose is ≥10 6 Gy, the bending strength is ≥80MPa, the visible light transmittance of chemically strengthened aluminosilicate glass is ≥92%, the surface hardness is ≥6H (Mohs hardness), the impact strength is ≥50kJ / m 2 , the salt spray resistance level is ≥96h (neutral salt spray), the density of polycarbonate is low, which can greatly reduce the weight of the finished composite film, and the impact strength is 200~300 times that of ordinary glass, which is not easy to break and has high safety, in addition, it also has certain ultraviolet resistance and high temperature resistance.

[0031] The bonding layer of the present application is preferably a Cr or Ti layer, which can form firm bonding with the substrate layer (such as quartz glass, polycarbonate, etc.) below and the dual-mechanism UV filtering functional layer above, avoiding interlayer peeling caused by large material difference between the substrate and the functional layer material, and ensuring the stability of the overall structure of the film body. In addition, The direct current magnetron sputtering method can efficiently deposit a Cr / Ti thin layer with a thickness of 2-20 nm, which is controllable and uniform, does not affect the light transmittance of the composite film, and provides a flat and clean substrate for the deposition of subsequent functional layers (such as disordered multilayer dielectric films), thereby reducing defects of subsequent film layers.

[0032] The double-mechanism UV filtering functional layer comprises a disordered multilayer dielectric film and a plasmonic resonance enhanced absorption layer.

[0033] The disordered multilayer dielectric film preferably comprises a high refractive index layer and a low refractive index layer, the material of the high refractive index layer is preferably Ta2O5 or HfO2, the material of the low refractive index layer is preferably SiO2, and the physical thickness of each layer is preferably randomly distributed between λ / 8n and λ / 2n, wherein λ is a random wavelength in the range of 250-420 nm, and n is the refractive index of the corresponding layer material.

[0034] More specifically, the high refractive index layer and the low refractive index layer are deposited in a non-periodic manner in the disordered multilayer dielectric film, and the thickness of each layer is randomly distributed according to λ / 8n to λ / 2n (λ is a random wavelength of 250-420 nm, and n is the refractive index of the material), which can form a wide range of reflection bands, completely covering the UVA (315-400 nm) and UVB (280-315 nm) bands, and avoiding the problems of traditional ordered films, such as narrow bandwidth and poor edge blocking rate. The non-periodic layer thickness design breaks the traditional ordered film rule that the reflection band blue shifts when the angle increases, so that UV light can be stably reflected even when the light is incident at a large angle, which is suitable for scenes with variable light incidence angles, such as space station portholes and outdoor artifact protective covers. By optimizing the combination and thickness of the high / low refractive index layers, the interference reflection loss of visible light is reduced while reflecting UV light, the overall visible light transmittance of the composite film is ensured, and the visual effect of display devices or the observation clarity of artifacts is not affected.

[0035] In the present application, the plasmonic resonance enhanced absorption layer comprises noble metal nanoparticles, semiconductor quantum dots and a dielectric matrix, the noble metal nanoparticles are silver nano-triangular plates or gold nanorods, the semiconductor quantum dots are ZnO or CsPbBr3 quantum dots, and the dielectric matrix is Al2O3 or SiO2, and the total thickness of the layer is 30-80 nm.

[0036] More preferably, the mass fraction of the noble metal nanoparticles, the semiconductor quantum dots and the dielectric matrix in the plasmonic resonance enhanced absorption layer is 5-15% for the noble metal nanoparticles, 8-20% for the semiconductor quantum dots, and the rest is the dielectric matrix.

[0037] More specifically, the noble metal nanoparticles in the plasmonic resonance enhanced absorption layer produce plasmonic resonance effect in the UV band, which can strongly absorb specific wavelength UV light; the semiconductor quantum dots can adjust the energy band gap due to the quantum size effect, and can absorb the UV band not covered by the noble metal particles, and the two can realize the dual protection of reflection + absorption, and greatly improve the UV blocking rate. In addition, the absorption peaks of the noble metal nanoparticles and the semiconductor quantum dots are accurately positioned in the UV band, and there is almost no absorption of visible light above 400 nm, avoiding the decrease of film transmittance or the appearance of color deviation (such as yellowing) caused by UV filtering function, and ensuring the display and observation requirements. The nanoparticles and quantum dots are fixed in the dielectric matrix, which can prevent particle agglomeration and migration, and avoid the problems of decreased transmittance and increased haze caused by uneven dispersion of nanoparticles; at the same time, the dielectric matrix protects the active ingredients and improves the weather resistance of the layer, which is suitable for long-term outdoor or aerospace applications. Finally, the total thickness of the layer is only 30-80 nm, which is thin and uniform, and will not increase the overall thickness or internal stress of the composite film, and can be stably compatible with the subsequent superhard layer and surface functional layer, avoiding the risk of film peeling and cracking caused by excessive layer thickness.

[0038] The superhard layer is a three-dimensional interpenetrating network structure formed by diamond-like carbon phase and hexagonal boron nitride nanosheet; In the present application, the volume ratio of the diamond-like carbon phase to the hexagonal boron nitride nanosheet in the superhard layer is preferably 1:1-3:1, and the layer thickness of the superhard layer is 50-200 nm.

[0039] The superhard layer of the present application provides excellent mechanical protection performance for the film body of the composite film. Specifically, the superhard layer adopts a three-dimensional interpenetrating network structure formed by diamond-like carbon phase and hexagonal boron nitride nanosheet, and the volume ratio of the two is controlled at 1:1-3:1 and the layer thickness is 50-200 nm. This structure gives it extremely high hardness and wear resistance, which can effectively resist scratches (such as accidental friction of display device touch operation and cultural relic protective cover), collisions or sand and dust impact in daily use, avoid scratches and damage on the surface of the film body, and thus protect the core structure of the double-mechanism UV filtering function layer below, and maintain the overall functional integrity of the composite film.

[0040] In addition, the three-dimensional interpenetrating network structure design of the superhard layer can reduce light scattering, and the optical properties of the diamond-like carbon phase and the hexagonal boron nitride nanosheet are adapted to other layers of the composite film, without additional absorption of visible light or interference with the blocking effect of the dual-mechanism UV filtering function layer on ultraviolet light, thereby protecting the core advantage of the composite film, i.e., high light transmittance, and avoiding the decline of the visual effect of the display device or the damage of the observation clarity of the cultural relics.

[0041] The surface functional layer is preferably a photocatalytic surface functional layer, and the photocatalytic surface functional layer is preferably a TiO2 / SiO2 composite material with a micro-nano hierarchical porous structure.

[0042] In the present application, the photocatalytic surface functional layer is specifically a three-dimensional macroporous framework formed by stacking mesoporous SiO2 spheres, and the inner wall of the pores is loaded with anatase TiO2 nanocrystals.

[0043] Specifically, the loaded anatase TiO2 nanocrystals have photocatalytic activity, can generate strong oxidizing hole-electron pairs under ultraviolet light irradiation, and can decompose organic pollutants attached to the surface. At the same time, the micro-nano hierarchical porous structure can increase the specific surface area and improve the efficiency of pollutant adsorption and photocatalytic reaction, and the reaction products can easily detach from the surface with airflow or rainwater, thereby realizing self-cleaning, avoiding the accumulation of pollutants affecting the light transmittance of the composite film (such as the visual effect of the display device or the observation clarity of the cultural relics protective cover), and reducing the frequency of manual cleaning.

[0044] In addition, the refractive indexes of SiO2 and TiO2 are well matched, and the micro-nano hierarchical porous structure design can reduce light scattering, so that the surface functional layer does not significantly reduce the visible light transmittance of the composite film, thereby ensuring that it does not interfere with the core requirement of high light transmittance, and balancing the self-cleaning function and optical performance.

[0045] In the present application, a stress buffer layer with a refractive index of 1.6-1.8 is preferably further arranged between the dual-mechanism UV filtering function layer and the superhard layer.

[0046] The present application also provides a preparation method of the composite functional film described in the above technical solution, which comprises the following steps: Pre-treatment of the substrate: ultrasonic cleaning and ion beam bombardment activation of the substrate; Deposition of the bonding layer: deposition of a Cr or Ti layer with a thickness of 2-20 nm by direct current magnetron sputtering; Deposition of the dual-mechanism UV filtering function layer: formation of the disordered multilayer dielectric film by non-periodically and alternately depositing high-refractive-index layers and low-refractive-index layers through real-time variation of the sputtering power and deposition time by using high-power pulse magnetron sputtering technology; The plasma resonance enhanced absorption layer is grown by a plasma enhanced chemical vapor deposition method in an inert gas and reaction gas atmosphere through co-deposition of a metal organic precursor and a semiconductor precursor; Depositing the superhard layer: a double-target co-sputtering combined with ion beam assisted deposition technology is adopted to sputter a graphite target and a hexagonal boron nitride target simultaneously, and an interpenetrating network structure of diamond-like carbon phase and hexagonal boron nitride nanosheet is formed under the substrate bias and ion bombardment; Depositing the surface functional layer: a sol-gel spin coating method combined with hydrothermal crystallization treatment is adopted to form a SiO2 microsphere template, introduce a titanium source for hydrothermal reaction, and finally obtain a anatase TiO2 / SiO2 composite photocatalytic layer through annealing treatment.

[0047] In the preparation of the composite functional film, the substrate layer is preferably pretreated first, and the substrate is ultrasonically cleaned and ion beam bombarded and activated, the pollutants such as oil stains, dust, residual impurities and the like on the surface of the substrate are efficiently removed through the breakage of micro-bubbles generated by ultrasonic vibration, and the adhesion of the subsequent bonding layer to the substrate is avoided from being affected by the pollutants, thereby providing a clean substrate for the deposition of the subsequent film layer. The substrate surface is bombarded by high-energy ions, which can further remove residual trace pollutants and improve the surface cleanliness, and on the other hand, can change the micro-topography of the substrate surface (such as forming micro concave-convex), increase the surface active sites, enhance the bonding strength of the subsequent bonding layer (Cr or Ti layer) to the substrate, and reduce the risk of interlayer peeling.

[0048] After the pretreatment of the substrate layer, the bonding layer is deposited, and specifically, the Cr or Ti layer is deposited by a direct current magnetron sputtering method, and the thickness is 2-20 nm.

[0049] More preferably, the process of depositing the bonding layer is specifically as follows: a high-purity Cr target or Ti target with a purity of ≥99.9% is selected and installed at the target position of a magnetron sputtering device to ensure the accurate relative position of the target material and the substrate and to ensure the uniformity of film formation; the pretreated substrate is placed in a sputtering chamber, and the vacuum degree is extracted to 10 -4 ~10 -6 Pa, then inert gas (such as Ar gas) is introduced as a sputtering gas to maintain a stable low-pressure atmosphere in the chamber, which is 0.1-1.0 Pa, to avoid the influence of impurity gas on the purity of the film layer; then a direct current power source is connected, and appropriate sputtering power and voltage are applied to ionize Ar gas to form plasma, and the Ar + In the electric field, the surface of the Cr target or Ti target is bombarded, so that the target atoms are separated from the target surface and migrate to the substrate surface; the deposition time is accurately controlled by real-time monitoring equipment to ensure that the thickness of the bonding layer is strictly controlled within the range of 2-20 nm; after the deposition is completed, the chamber is maintained in a vacuum or inert atmosphere environment, and the substrate and the bonding layer are naturally cooled to room temperature to avoid film cracking or stress concentration caused by sudden temperature change, and finally a uniform and dense Cr layer or Ti layer is formed.

[0050] The deposition of the dual-mechanism UV filtering functional layer: using high-power pulsed magnetron sputtering technology, by changing the sputtering power and deposition time in real time, non-periodically alternating deposition of high refractive index layers and low refractive index layers to form the disordered multilayer dielectric film; In the present application, the pulse frequency of the high-power pulsed magnetron sputtering technology is preferably 100-500 Hz, the duty cycle is preferably 50%-90%, and the substrate table temperature is preferably 200-300℃.

[0051] The deposition process of the disordered multilayer dielectric film in the present application is more preferably: selecting high refractive index target material (Ta2O5 or HfO2) and low refractive index target material (SiO2) and installing them in the corresponding target positions of the high-power pulsed magnetron sputtering equipment; fixing the substrate with the deposited bonding layer on the substrate table and ensuring that the substrate table temperature is preheated to 200-300℃. Vacuumize the sputtering chamber to achieve a vacuum degree of usually 10 -4 ~10 -6 Pa, and introduce inert gas (such as Ar gas) as sputtering gas, maintain the chamber pressure at 0.1~1.0 Pa stably, avoid impurities affecting the purity of the film layer. Set the pulse frequency to 100-500 Hz and the duty cycle to 50%-90%, and adjust the sputtering power and deposition time of the high / low refractive index target material in real time through the equipment control system to realize non-periodic alternating deposition - not following a fixed layer thickness order, but making the physical thickness of each layer randomly distributed within the range of “λ / 8n to λ / 2n” (λ is a random wavelength of 250-420 nm, n is the refractive index of the corresponding layer material). Real-time tracking of the UV reflection band coverage of the film layer is realized through an optical monitoring system (such as a spectrometer), and after the reflection band completely covers the 250-420 nm (UVA+UVB) band, the sputtering is stopped to form the disordered multilayer dielectric film.

[0052] The plasma resonance enhanced absorption layer is grown by plasma enhanced chemical vapor deposition method in an inert gas and reaction gas atmosphere in a co-deposition manner of metal organic precursor and semiconductor precursor; In the present application, the metal organic precursor used for growing the plasma resonance enhanced absorption layer is preferably trimethylaluminum or tetraethyl orthosilicate, the semiconductor precursor is preferably diethyl zinc hexane solution, and the plasma power is preferably 200-500 W.

[0053] The deposition process of the plasmonic resonance enhanced absorption layer is more preferably: preparing metal organic precursors (trimethylaluminum or tetraethyl orthosilicate) and semiconductor precursors (hexane solution of diethyl zinc), and proportionally accessing the precursor delivery system of the deposition equipment; inert gas and a small amount of reaction gas (such as O2, auxiliary precursor decomposition) are introduced into the chamber to maintain a stable atmosphere. Turn on the plasma power, set the power to 200-500W, ionize the gas in the chamber to form a plasma; the plasma energy excites the metal organic precursor and the semiconductor precursor to co-decompose on the surface of the disordered multilayer dielectric film, and the dielectric matrix gradually forms the substrate, while the noble metal nanoparticles (silver nano-triangular plate or gold nano-rod, converted from the metal component in the precursor) and the semiconductor quantum dots (ZnO or CsPbBr3) are uniformly dispersed in the matrix. Adjust the layer thickness by deposition time to ensure that the total thickness is controlled within 30-80nm (to avoid affecting the light transmittance due to excessive thickness); monitor the microstructure of the film layer during the process to ensure that the nanoparticles and quantum dots are not agglomerated and are uniformly distributed in the dielectric matrix to form a stable plasmonic resonance enhanced absorption layer.

[0054] Depositing a superhard layer: using double-target co-sputtering combined with ion beam assisted deposition technology, sputtering graphite target and hexagonal boron nitride target at the same time, forming an interpenetrating network structure of diamond-like carbon phase and hexagonal boron nitride nanosheet under the action of substrate bias and ion bombardment; The specific process of depositing a superhard layer is preferably: selecting high-purity graphite target and hexagonal boron nitride target, and installing them on the corresponding target positions of the double-target co-sputtering equipment to ensure that the distance between the two targets and the substrate is consistent and the angle is suitable; fix the substrate on which the double-mechanism UV filtering functional layer has been deposited on the substrate table that can apply a bias, check that the substrate surface is free of impurities and scratches to ensure that the deposition substrate is clean and flat. Close the sputtering chamber, start the vacuum pump group to pump the chamber to an ultra-high vacuum degree of 10 -4 ~10 -6 Pa to exclude the influence of impurity gases such as air and water vapor on the purity of the film layer; then introduce inert gas as the sputtering gas to maintain the chamber pressure at 0.1-1.0Pa, and connect the double-target sputtering power supply to apply appropriate sputtering power to the graphite target and the hexagonal boron nitride target; at the same time, turn on the substrate table bias system to apply a negative bias (usually -50--200V) to form an electric field on the substrate surface to guide the directional deposition of sputtered particles. Start the ion beam source to generate high-energy inert ions (such as Ar + ) and direct them to bombard the substrate surface and the film layer being deposited; on the one hand, high-energy ions can "bombard and densify" the film layer to reduce internal voids and improve structural density and hardness; on the other hand, carbon ions sputtered from the graphite target can form a diamond-like structure (sp 3Hybridization), while assisting the uniform dispersion of hexagonal boron nitride nanosheets, and promoting the formation of a three-dimensional interpenetrating network - the diamond-like carbon phase provides high hardness, and the hexagonal boron nitride nanosheets improve the toughness of the film layer to avoid brittle fracture of the film layer. The composition ratio of the diamond-like carbon phase and the hexagonal boron nitride nanosheet in the film layer is tracked in real time by a monitoring device to ensure that the volume ratio of the two is stable at 1:1~3:1; at the same time, the deposition thickness is monitored by a quartz crystal microbalance, and when the thickness reaches 50-200nm, the sputtering power and ion beam intensity are gradually reduced to prepare for the termination of deposition.

[0055] Depositing a surface functional layer: using a sol-gel spin coating method combined with hydrothermal crystallization treatment, first forming a SiO2 microsphere template, then introducing a titanium source for hydrothermal reaction, and finally obtaining an anatase TiO2 / SiO2 composite photocatalytic layer through annealing treatment.

[0056] More preferably, specifically: taking the substrate with the deposited superhard layer as the base, preparing SiO2 microsphere template preparation raw materials, titanium source (such as tetrabutyl titanate), etc., and building a sol-gel spin coating and hydrothermal reaction device. Using a sol-gel spin coating method, the SiO2 sol is uniformly spin-coated on the surface of the substrate, and after drying treatment, a three-dimensional macroporous framework template of mesoporous SiO2 sphere accumulation is formed. Put the substrate with the SiO2 template into the reaction kettle, add the titanium source solution, control the temperature and time for hydrothermal reaction, and make the titanium source generate TiO2 precursor in the inner wall of the macroporous framework pores. Place the hydrothermally treated substrate in an annealing furnace and anneal at a specific temperature to convert the TiO2 precursor into anatase TiO2 nanocrystals, and finally form a TiO2 / SiO2 composite photocatalytic surface functional layer.

[0057] The application also provides the application of the composite functional film in the preparation of a space station porthole, a high-end military display device, or a long-term protective cover for precious cultural relics outdoors.

[0058] Example 1 1. Raw material and equipment preparation Substrate: quartz glass with a thickness of 2mm (visible light transmittance ≥93%, anti-radiation dose ≥10 6 Gy); Target material: Cr target (purity 99.9%), Ta2O5 target (high refractive index, purity 99.9%), SiO2 target (low refractive index, purity 99.9%), graphite target (purity 99.9%), hexagonal boron nitride target (purity 99.9%); Precursor: trimethylaluminum (metal-organic precursor), diethylzinc hexane solution (semiconductor precursor, concentration 0.1mol / L), tetrabutyl titanate (titanium source), and tetraethyl orthosilicate (SiO2 microsphere raw material); Equipment: ultrasonic cleaning machine, ion beam activation instrument, direct current magnetron sputtering equipment, high-power pulsed magnetron sputtering equipment, plasma enhanced chemical vapor deposition (PECVD) equipment, double-target co-sputtering + ion beam assisted deposition equipment, sol-gel spin coater, hydrothermal reactor, annealing furnace.

[0059] 2. Preparation steps (1) Pretreatment of substrate Put the quartz glass into the ultrasonic cleaning machine, clean it with ethanol-deionized water mixture (volume ratio 1:1) for 30 min to remove surface oil and dust; then transfer it to the ion beam activation instrument, introduce Ar gas, and bombard the substrate surface with an ion beam of 500 eV energy for 10 min to enhance the surface activity.

[0060] (2) Deposition of bonding layer Use the direct current magnetron sputtering equipment, fix the pretreated substrate on the substrate table, vacuumize to 10 -5 Pa, introduce Ar gas to maintain the chamber pressure at 0.5 Pa; turn on the Cr target sputtering power source, set the sputtering power to 100 W, and deposit for 3 min to form a Cr bonding layer with a thickness of 8 nm.

[0061] (3) Deposition of double-mechanism UV filtering functional layer Disordered multilayer dielectric film: use high-power pulsed magnetron sputtering equipment, preheat the substrate table to 250°C, pulse frequency 300 Hz, duty cycle 70%; alternately sputter Ta2O5 target (high refractive index layer) and SiO2 target (low refractive index layer), adjust the sputtering power (Ta2O5 target 80 W, SiO2 target 60 W) and deposition time (10-20 s per layer) in real time to make the thickness of each layer randomly distributed in the range of λ / 8n~λ / 2n (λ takes a random value of 250-420 nm, Ta2O5 refractive index n=2.1, SiO2 refractive index n=1.5), a total of 15 layers, total thickness about 180 nm.

[0062] Plasmonic resonance enhanced absorption layer: transfer to PECVD equipment, vacuumize to 10 -4 Pa, introduce Ar gas (flow rate 20 sccm) and O2 gas (flow rate 5 sccm) to maintain the chamber pressure at 1.0 Pa; introduce trimethylaluminum (flow rate 0.5 sccm) and diethyl zinc hexane solution (flow rate 0.3 sccm) into the chamber, set the plasma power to 300 W, and deposit for 5 min to form an absorption layer (containing silver nano-triangle plate, ZnO quantum dots, and Al2O3 dielectric matrix, mass ratio 10%, 15%, and 75%, respectively) with a thickness of 50 nm.

[0063] (4) Deposition of superhard layer Use double-target co-sputtering + ion beam assisted deposition equipment, fix the substrate, vacuumize to 10-5 Pa, Ar gas was introduced to maintain the chamber pressure at 0.8 Pa; at the same time, the graphite target (sputtering power 150 W) and the hexagonal boron nitride target (sputtering power 120 W) were turned on, a substrate bias of -100 V was applied, and the ion beam source (Ar + 800 eV) was started, and the deposition time was 15 min, forming a superhard layer (volume ratio of diamond-like carbon phase to hexagonal boron nitride nanosheet 2:1) with a thickness of 120 nm.

[0064] (5) Depositing a surface functional layer SiO2 sol (tetraethyl orthosilicate: ethanol: water: hydrochloric acid = 1:4:1:0.01, molar ratio) was prepared and spin-coated on the surface of the superhard layer at a speed of 3000 r / min using a sol-gel spin coater, and then dried at 80°C for 1 h to form a SiO2 microsphere three-dimensional macroporous framework. The substrate was placed in a hydrothermal reactor, and tetrabutyl titanate-ethanol solution (concentration 0.2 mol / L) was added, and hydrothermal reaction was carried out at 120°C for 4 h to load TiO2 precursor on the inner wall of the pores; then it was transferred to an annealing furnace and annealed at 500°C in air for 2 h to obtain an anatase TiO2 / SiO2 surface functional layer (thickness about 30 nm), and finally a composite functional film was prepared.

[0065] Performance and testing 1. Test sample The composite functional film prepared in Example 1 above was used as the experimental group, and uncoated quartz glass was used as the control group.

[0066] 2. Test items and methods (1) Visible light transmittance test According to GB / T 2410-2008 "Determination of Transmittance and Haze of Transparent Plastics", an ultraviolet-visible spectrophotometer was used to test the transmittance in the wavelength range of 400-800 nm, and the average transmittance was recorded.

[0067] (2) UV blocking rate test An ultraviolet spectrophotometer was used to test the transmittance in the wavelength range of 280-315 nm (UVB) and 315-400 nm (UVA), respectively, and the UV blocking rate was calculated according to "UV blocking rate = 1-UV transmittance".

[0068] (3) Hardness test According to GB / T 6739-2021 "Determination of Film Hardness of Pigment and Varnish by Pencil Method", a pencil hardness tester was used to test from 6H to 2B, and the highest pencil hardness grade without scratches was recorded.

[0069] (4) Self-cleaning performance test In the experimental group and the control group, 0.1 mL of methylene blue solution with a concentration of 0.1% (simulating organic pollutants) was added on the surface, and was irradiated under a 30W ultraviolet lamp (wavelength 254nm) for 2h. The absorbance of the methylene blue solution before and after irradiation was tested by a spectrophotometer (wavelength 664nm). The self-cleaning effect was evaluated according to the formula "degradation rate = (initial absorbance- absorbance after irradiation) / initial absorbance x 100%".

[0070] The test results are shown in Table 1: Table 1 Test results of the experimental group and the control group

[0071] Based on Table 1, it can be seen that the composite functional film prepared in Example 1 of the present application has high visible light transmittance (91.5%), efficient blocking of UVB and UVA, high hardness and excellent self-cleaning performance, and meets the use requirements of high-end scenarios such as space station portholes, outdoor cultural relic protective covers, etc.

[0072] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application. Any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered within the protection scope of the claims of the present application.

Claims

1. A composite functional membrane with high light transmittance and UV filtration properties, characterized in that, From bottom to top, they include: Substrate layer, bonding layer, dual-mechanism UV filtration functional layer, superhard layer and surface functional layer; The bonding layer is a Cr or Ti layer; The dual-mechanism UV filtration functional layer includes a disordered multilayer dielectric membrane and a plasma resonance enhanced absorption layer. The superhard layer is a three-dimensional interpenetrating network structure formed by diamond-like carbon phase and hexagonal boron nitride nanosheets; The surface functional layer is a photocatalytic surface functional layer, which is a TiO2 / SiO2 composite material with a micro-nano hierarchical porous structure.

2. The composite functional membrane with high light transmittance and UV filtration as described in claim 1, characterized in that, The disordered multilayer dielectric film includes a high refractive index layer and a low refractive index layer. The high refractive index layer is made of Ta2O5 or HfO2, and the low refractive index layer is made of SiO2. The physical thickness of each layer is randomly distributed between λ / 8n and λ / 2n, where λ is a random wavelength in the range of 250nm to 420nm, and n is the refractive index of the corresponding layer material.

3. The composite functional membrane according to claim 1, characterized in that, The plasma resonance enhancement absorption layer comprises noble metal nanoparticles, semiconductor quantum dots, and a dielectric matrix. The noble metal nanoparticles are silver nanoplatelets or gold nanorods, the semiconductor quantum dots are ZnO or CsPbBr3 quantum dots, and the dielectric matrix is ​​Al2O3 or SiO2. The total thickness of the layer is 30-80 nm.

4. The composite functional membrane according to claim 1, characterized in that, The volume ratio of diamond-like carbon phase to hexagonal boron nitride nanosheets in the superhard layer is 1:1 to 3:1, and the thickness of the superhard layer is 50-200 nm.

5. The composite functional membrane according to claim 1, characterized in that, The photocatalytic surface functional layer is specifically a three-dimensional macroporous framework formed by the stacking of mesoporous SiO2 spheres, with anatase TiO2 nanocrystals loaded on the inner walls of its pores.

6. The composite functional membrane according to claim 1, characterized in that, A stress buffer layer is provided between the dual-mechanism UV filter functional layer and the ultra-hard layer. The stress buffer layer is a silicon oxynitride layer with a refractive index between 1.6 and 1.

8.

7. A method for preparing the composite functional membrane according to any one of claims 1 to 6, characterized in that, Includes the following steps: Substrate pretreatment: The substrate is subjected to ultrasonic cleaning and ion beam bombardment activation; Deposition bonding layer: Cr or Ti layer with a thickness of 2-20 nm is deposited by DC magnetron sputtering; Dual-mechanism UV filter functional layer deposition: High-power pulsed magnetron sputtering technology is used to non-periodically deposit high-refractive-index layers and low-refractive-index layers by changing the sputtering power and deposition time in real time, forming the disordered multilayer dielectric film; The plasma resonance enhanced absorption layer was grown in an inert gas and reactive gas atmosphere by using plasma-enhanced chemical vapor deposition with co-deposition of metal-organic precursors and semiconductor precursors. Depositing an ultrahard layer: A dual-target co-sputtering combined with ion beam-assisted deposition technology is used to simultaneously sputter graphite targets and hexagonal boron nitride targets. Under substrate bias and ion bombardment, an interpenetrating network structure of diamond-like carbon phase and hexagonal boron nitride nanosheets is formed. Deposited surface functional layer: The sol-gel spin coating method combined with hydrothermal crystallization treatment is used to first form SiO2 microsphere template, then introduce titanium source for hydrothermal reaction, and finally annealing treatment to obtain anatase TiO2 / SiO2 composite photocatalytic layer.

8. The preparation method according to claim 7, characterized in that, The high-power pulsed magnetron sputtering technology has a pulse frequency of 100-500Hz, a duty cycle of 50%-90%, and a substrate stage temperature of 200-300℃.

9. The preparation method according to claim 7, characterized in that, The metal-organic precursor used to grow the plasma resonance enhancement absorption layer is trimethylaluminum or tetraethyl orthosilicate, the semiconductor precursor is a hexane solution of diethylzinc, and the plasma power is 200-500W.

10. The application of the composite functional membrane according to any one of claims 1 to 6 in the preparation of space station portholes, high-end military display equipment or long-term protective covers for precious outdoor cultural relics.

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