A functional film

Abstract

The utility model provides a kind of functional film, belong to functional film technical field.The utility model's functional film includes base material layer and the closed cavity inlay in the base material layer.The utility model's functional film only includes a layer of base material layer, more light and thin, optical absorption is lower, heat transfer performance is better;And relative to laminated structure, there is no interface mismatch risk, low in cost, there is no laminated interface, avoid delamination caused by moisture penetration under high temperature and high humidity environment, higher environmental aging resistance, and need not laminating.The utility model's functional film in solar cell field, can improve the structural stability of heat dissipation and packaging, improve the power generation efficiency of solar module, long-term working life and environmental tolerance, in display field, its light and thin, flexible and non-heterogeneous characteristics make it have good application space in precision optical device.

Description

Technical Field

[0001] This utility model relates to the field of functional film technology, and in particular to a functional film. Background Technology

[0002] Optical functional thin films play a crucial role in many modern technology fields, such as improving energy conversion efficiency, optimizing information display effects, and realizing new optoelectronic devices. In particular, in the fields of solar photovoltaics and information display, which have high requirements for optical performance, material stability, and cost-effectiveness, the demand for advanced optical thin film structures is becoming increasingly urgent.

[0003] In the field of solar photovoltaics, there are a lot of gaps between solar cell cells and between the cells and the frame. Therefore, gap films are installed in the gaps to improve light utilization.

[0004] There are several types of gap film structures: (1) Traditional glazed glass: Traditional glazed glass improves light utilization through diffuse reflection, but it has problems such as low reflection efficiency and high breakage rate, and there is a strong trend to be replaced by microprism structure; (2) Mainstream microprism coating structure: Mainstream microprism coating structure achieves light reflection by coating a metal reflective film (such as aluminum film) on the microprism structure; (3) Diffuse reflection film based on material modification: Mesoporous composite materials are applied to the gap film to improve the reflectivity of special bands, but the structural innovation is insufficient; (4) Laminated structure containing optical cavity: The optical cavity is sealed by laminating a double-layer structure, and the optical function is achieved by the difference in refractive index between the substrate of the double-layer structure and the optical cavity.

[0005] With the increasing demands for lightweight and flexible photovoltaic modules, as well as for higher power density and long-term reliability, developing new interstitial membrane technologies that combine high light utilization, excellent weather resistance, structural stability, and low cost has become a crucial issue that the industry urgently needs to address.

[0006] Meanwhile, in the field of light guide display devices, high-performance optical films are also an indispensable core component of modern display panels. These optical films are used to achieve a variety of key functions in backlight modules, such as improving light efficiency, uniform light distribution, viewing angle control, color enhancement, polarization management, and screen protection. The continuous pursuit of thinner, lighter, more flexible, higher image quality (such as high brightness, high color gamut, and high contrast) and lower power consumption in display devices poses severe and ongoing challenges to the precision structural design, material selection, and manufacturing processes of related optical films. Utility Model Content

[0007] In view of this, the purpose of this utility model is to provide a functional membrane. The functional membrane provided by this utility model consists of only one substrate material layer, has low cost, and is simple to prepare, requiring no lamination.

[0008] To achieve the above-mentioned objectives, this utility model provides the following technical solution:

[0009] This invention provides a functional membrane, comprising a matrix material layer and a closed cavity embedded in the matrix material layer, wherein the closure of the closed cavity is achieved by forming an integrated sealing structure in situ within the matrix material layer.

[0010] Preferably, the height of the enclosed cavity is 10–65 μm.

[0011] Preferably, the geometry of the enclosed cavity includes protrusions, ridges, recesses, binary forms, inclined forms, square forms, triangular forms, grating pixel forms, trapezoidal forms, or lens forms.

[0012] Preferably, the functional film further includes a gradient refractive index layer.

[0013] Preferably, the surface of the matrix material layer has a microstructure.

[0014] Preferably, the surface of the substrate material layer is further provided with an additional functional layer, which includes one or more of coatings, films, and surface structures.

[0015] Preferably, the enclosed cavity contains contents, which include fluids and / or solids.

[0016] Preferably, the fluid includes air; the solid includes one or more of temperature-sensitive materials, photosensitizing materials, and functional materials.

[0017] This utility model also provides a solar cell module, including a stacked structure from top to bottom: tempered glass, an upper encapsulating film, solar cells arranged side by side, a lower encapsulating film, and a backsheet. The functional film is disposed between two adjacent solar cells, or / and in the gap between the solar cells and the module frame.

[0018] This utility model also provides a side-lit backlight module, including a reflective sheet, a light guide plate, a lower diffuser sheet, a prism sheet, and an upper diffuser sheet, wherein the light guide plate is the functional film described in the above technical solution.

[0019] This invention provides a functional membrane, comprising a matrix material layer and a closed cavity embedded in the matrix material layer.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] The functional film provided by this invention forms an integrated closed structure in situ through the matrix material, eliminating the physical interface between different layers in the traditional laminated structure. Therefore, it fundamentally avoids failure modes such as interface delamination and cracking caused by poor interface adhesion, material thermal mismatch or moisture penetration, and significantly improves the structural stability and service life of the functional film under harsh environments (such as long-term outdoor operation of solar modules and repeated bending of flexible display devices).

[0022] Furthermore, since the sealing is a natural continuation or highly compatible combination of the matrix material layers, it avoids light scattering, absorption or abrupt changes in refractive index that may be caused by heterogeneous interfaces, which is beneficial to maintaining excellent optical performance (such as high transmittance and uniform optical response).

[0023] In addition, the functional film of this invention is a single substrate material layer, which has significant advantages over multi-layer lamination in terms of thinness, flexibility, reduced material costs, and simplification of some manufacturing processes. It also has lower optical absorption and better heat transfer performance, thus having good application potential in the fields of solar cells and optical displays. Attached Figure Description

[0024] Figure 1 A schematic diagram of a functional membrane structure containing a closed cavity;

[0025] Figure 2 This is a schematic diagram of the structure of the matrix material layer before reflow.

[0026] Figure 3 This is a schematic diagram of the surface microstructure of the functional membrane of the epitaxial removable template and the springback area before springback.

[0027] Figure 4 A schematic diagram of a functional membrane structure including a functional material layer for a removable template;

[0028] Figure 5 The optical transmission simulation diagram of the thin film with a laminated structure in Comparative Example 1 is shown.

[0029] Figure 6 This is a simulated optical transmission diagram of the functional film in Embodiment 1 of this utility model;

[0030] Figure 7 This is a luminous flux test diagram of the thin film with a laminated structure in Comparative Example 1;

[0031] Figure 8 This is a light flux test diagram of the functional film in Example 1. Detailed Implementation

[0032] This invention provides a functional membrane, comprising a substrate material layer and a closed cavity embedded in the substrate material layer, wherein the closed cavity has at least one predetermined optical function relative to the capture of incident light and / or the capture of internally reflected light.

[0033] In this invention, the functional film has no lamination interface, avoiding delamination caused by moisture penetration under high temperature and humidity conditions. It exhibits high resistance to environmental aging and is lightweight. The functional film of this invention comprises only one substrate material layer, making it thinner and lighter, with lower optical absorption and better heat transfer performance. Compared to laminated structures, it eliminates the risk of interface mismatch, has lower cost, avoids delamination caused by moisture penetration under high temperature and humidity conditions, has high resistance to environmental aging, and is simple to prepare without lamination. In the field of solar cells, this functional film can improve the power generation efficiency, long-term operating life, and environmental tolerance of solar modules by improving heat dissipation and the structural stability of the encapsulation. In the field of displays, its thinness, flexibility, and non-heterogeneous characteristics make it well-suited for applications in precision optical devices.

[0034] The functional film of this invention has a single-layer structure. Compared with the laminated structure in the prior art, the functional film provided by this invention does not require lamination, and its "top layer" is relatively thin. The optical advantages are reflected in the thin top layer and fewer interfaces: a thin top layer reduces the absorption and scattering of light by the material, improves light transmittance, and optimizes off-axis performance, reducing the change in path length when light is obliquely incident; fewer interfaces (such as replacing PET-adhesive-PET-air and other multi-layer structures with PET-air) can reduce Fresnel reflection loss and scattering sources, thereby improving total transmittance, reducing haze and stray light, and can also improve image clarity or signal-to-noise ratio in optical applications.

[0035] In this invention, the optical function is preferably obtained and constituted through the internal structure of the embedded closed cavity and the size, material, position and / or alignment of the contents of the closed cavity.

[0036] In this invention, when the surface of the functional film has a microstructure and / or an additional functional layer with optical function, the optical function is preferably obtained and constituted through the microstructure and the additional functional layer with optical function.

[0037] In this invention, the design space of the closed cavity is free. Through the synergistic advantages of materials and structure, a functional layer is preferably deposited on the cavity wall to enhance the overall optical benefits. The material of the functional layer preferably includes TiO2 or SiO2-TiO2 composite layer.

[0038] In this invention, the closed cavity is preferably obtained by at least one of embossing, stamping, photolithography, molding, casting and removable template, more preferably by a removable template. The removable template, relative to stamping, can form a closed cavity structure with a small opening and a large cavity.

[0039] In this invention, the material of the removable template is preferably blended with the substrate by pre-embedding the template, and combined with the template removal mechanism and the material rebound and / or material reflow mechanism of the substrate material layer, so as to achieve precise control and stable encapsulation of the closed cavity structure, and provide a new technical path for improving the efficiency of functional membrane components.

[0040] In one embodiment of this utility model, the matrix material layer preferably incorporates a soluble material (such as polyvinyl alcohol, PVA) during the molding process. After the matrix is ​​cured, the soluble material is dissolved to form an embedded cavity. Combined with the substrate rebound mechanism, the closed cavity is obtained.

[0041] In this invention, the closed cavity is preferably obtained by co-extrusion casting. In a specific embodiment of this invention, the base material layer and the removable template are preferably co-extruded using a co-extrusion device to form an integrated structure, thereby obtaining the closed cavity.

[0042] In this invention, the removable template is preferably designed to include a deformation compensation design to compensate for cavity deformation during the process.

[0043] In this invention, the material of the removable template and the material of the matrix material layer are preferably chemically stable.

[0044] In this invention, the number of enclosed cavities is preferably greater than one, and the multiple enclosed cavities preferably have the same function or at least multiple functions designed together.

[0045] In this invention, the geometric form of the closed cavity preferably includes a protrusion, a ridge, a recess, a binary form, an inclined form, a square form, a triangular form, a grating pixel form, a trapezoidal form, or a lens form.

[0046] In this invention, the height of the enclosed cavity is preferably 10 to 65 μm, specifically 10, 20, 30, 40, 50, 55, 60 or 65 μm.

[0047] In this invention, the closed cavity is preferably sealed by a self-sealing layer, which preferably originates from the material rebound and / or material reflow of the substrate material layer. Preferably, an interlocking / optical microstructure is formed between the substrate material layer and the self-sealing layer. In a specific embodiment of this invention, the closed cavity is obtained by a removable template, and the closed cavity is sealed by the material rebound of the substrate material layer. The removable template is preferably a partially epitaxial template, and the epitaxial region guides the substrate to rebound at the cavity opening to form an interlocking / optical microstructure. During the process, the removable template is controlled to rebound to the point of cavity closure after removal (and cleaning).

[0048] In this invention, the "springback" in material springback refers to the elastic recovery of the base material layer. The self-sealing layer formed by the material springback refers to the elastic recovery deformation of the base material layer at the opening after a front cavity structure with an opening is formed by means of imprinting, mold removal, or sacrificial template removal. This deformation causes the opening to shrink or close, forming a self-sealing layer. In a specific embodiment of this invention, the base material layer preferably contains a shape memory polymer. Through preset programming steps, under specific external stimuli (such as temperature changes), the base material layer around the front cavity structure with the opening undergoes a preset shape recovery, achieving self-sealing of the opening. In another embodiment of this invention, the base material layer generates internal residual stress during the molding process, which is released after the opening is formed. This release of internal residual stress may synergistically promote the self-sealing of the opening.

[0049] In this invention, the material reflow forming a self-sealing layer refers to the process of locally heating or inputting other energy into the opening edge region of the front cavity structure with an opening, causing the material of the matrix material layer to soften, melt, and flow in that region. Driven by surface tension or capillary force, the molten matrix material layer bridges and seals the opening. After cooling and solidification, a closed cavity is formed integral with the matrix material layer. The capillary force helps prevent the molten matrix material layer from collapsing into the closed cavity and promotes the bridging and sealing of the opening.

[0050] In this invention, the material reflow preferably utilizes a focused laser beam to precisely irradiate the opening edge region of the front cavity structure (laser fusion), causing the substrate material layer to locally melt in this region. The molten material flows and re-solidifies under the influence of surface tension, thereby sealing the opening and forming a closed cavity integral with the substrate material layer. In this invention, the laser fusion is characterized by non-contact, high precision, and localized heating, making it suitable for the precise sealing of tiny openings. By adjusting the laser parameters of the laser fusion (including power, pulse width, and scanning path), precise control of the melting area and the sealing process can be achieved.

[0051] In this invention, the functional film preferably further includes a gradient refractive index layer (GRIN layer), the material of which is preferably the same as that of the substrate material layer, differing only in material density. In this invention, the GRIN layer is preferably formed during a laser fusion process.

[0052] In this invention, the interaction between the laser and the substrate material layer during the laser fusion process may also generate a slight change in refractive index around the fusion region, bringing additional optical functions to the device. The monolithic structure (including the substrate material layer and the enclosed cavity embedded in the substrate material layer) makes the area of ​​refractive index change around the enclosed cavity an integral part of the optical design, rather than an interface effect, unlike laminated structures. It also eliminates the need to fabricate a separate GRIN layer (e.g., generating a refractive index gradient GRIN layer in the surrounding substrate material layer while using laser to seal the opening). This GRIN effect can be adjusted by controlling the laser parameters, thereby achieving unique optical functions directly integrated with the enclosed cavity.

[0053] In this invention, the material rebound and material reflow preferably occur simultaneously. If rebound and reflow occur simultaneously under heat assistance, the material rebound has problems such as incomplete closure, weak interfacial bonding, and insufficient long-term stability. If the material reflow closes a large initial opening, it may require higher temperatures and longer heating times, or face challenges such as molten material collapse, uneven flow, and impact on flatness. Combining the material rebound and material reflow can leverage the advantages and avoid the disadvantages, improve efficiency, and broaden the process window.

[0054] In this invention, the material rebound and material reflow preferably occur simultaneously, enabling more complete sealing within a relatively low temperature (preferably 90–170°C, specifically 90, 130, or 170°C) and a short time (preferably 2–30 seconds, specifically 2, 10, 20, or 30 seconds), and reducing the thermal impact or deformation caused by large-scale reflow. During the simultaneous occurrence of material rebound and material reflow, it is preferable to apply a small auxiliary pressure (more preferably 0.01–0.3 MPa, specifically 0.01, 0.05, 0.1, 0.2, or 0.3 MPa) to help ensure close contact and fusion of the rebound / reflow interface.

[0055] In this invention, the surface of the substrate material layer preferably has a microstructure, that is, the self-sealing layer preferably has a functional surface microstructure. The microstructure is the in-situ microstructure of the substrate material layer, which can be obtained during the preparation of the substrate material layer or during the in-situ sealing process.

[0056] In this invention, the substrate material layer is preferably disposed in the gap structure between the solar cell and the battery or / and between the battery and the frame, or disposed in the layer structure above / below the gap between the solar cell and the battery or / and between the battery and the frame.

[0057] In this invention, the substrate material layer preferably comprises an optically transparent material.

[0058] In this invention, the substrate material layer is preferably composed of one or more of ethylene-vinyl acetate copolymer (EVA), polyethylene terephthalate (PET), polyolefin elastomer (POE), and their modified materials.

[0059] In this invention, the matrix material layer preferably includes a springy region and / or a rigid region, and the elastic modulus of the springy region and / or the rigid region is different from that of the non-springy region and / or the rigid region of the matrix material layer. In a specific embodiment of this invention, the matrix material layer has a springy region at the opening of the closed cavity, and the differentiated elastic modulus setting facilitates the self-sealing of the closed cavity opening.

[0060] In this invention, the surface of the substrate material layer is preferably further provided with an additional functional layer, which preferably includes one or more of a coating, a film, and a surface structure. The coating and the film are preferably planar structures. The coating is chemically bonded, and the film is obtained by multi-layer lamination, such as including hot-press bonding. The surface structure is preferably a non-planar structure that serves an optical function.

[0061] In this invention, the additional functional layer preferably includes, but is not limited to, an optical functional layer, a mechanical functional layer, a self-cleaning layer, and a weather-resistant functional layer. Specifically, the coating is preferably an anti-reflective coating, more preferably a nano-scale silica / titanium dioxide composite coating, and the film is preferably a composite film with both optical and anti-aging properties, more preferably an acrylate antireflective coating with a UV absorber as the inner layer and a silica-alumina wear-resistant layer as the outer layer.

[0062] In this invention, the substrate material layer and the enclosed cavity preferably have different refractive indices.

[0063] In this invention, the enclosed cavity includes an inclusion, which preferably includes a fluid and / or a solid, and the inclusion is preferably contained inside the enclosed cavity before the enclosed cavity is closed.

[0064] In this invention, the fluid preferably includes air.

[0065] In this invention, the solid preferably includes one or more of the following: temperature-sensitive materials, photosensitizing materials, and functional materials.

[0066] In this invention, the temperature-sensitive material and the photosensitive material independently include poly(N-isopropylacrylamide) (PNIPAM) and / or paraffin-based composites, which can achieve dynamic control of the closed cavity.

[0067] In this invention, the functional material preferably includes TiO2, which can form a closed cavity internal microstructure, creating synergistic optical benefits with the closed cavity structure and balancing light transmittance, reflection gain and mechanical properties.

[0068] This utility model also provides a method for preparing the functional membrane described in the above technical solution, comprising the following steps:

[0069] By opening the base material, a front cavity structure with an opening is obtained;

[0070] The front cavity structure is sealed to form a closed cavity, thus obtaining the functional membrane.

[0071] This invention creates an opening in the base material to obtain a front cavity structure with an opening.

[0072] The present invention preferably obtains the front cavity structure by at least one of embossing, stamping, photolithography, molding, casting or a removable template.

[0073] In this invention, at least one of the closed cavities is obtained by removing the removable template, which is preferably removed by at least one of template etching, degradation, phase transition, or absorption. In one specific embodiment of this invention, a functional membrane is prepared by synergistically employing multiple template removal methods.

[0074] In this invention, the etched substrate for the template etching preferably includes CaCO3 micro / nano particles and / or ZnO micro / nano particles.

[0075] In this invention, the front cavity structure is preferably obtained by removing a removable template. The removal process is preferably a multi-stage removal process. By adjusting the reaction conditions, sudden environmental changes are avoided, which facilitates the gradual release of gas, avoids the generation of mist (gas and product mixing), ensures thorough removal, and enhances the stability of the cavity structure.

[0076] After the removable template is removed, a post-cleaning process is preferably included to obtain the front cavity structure.

[0077] In this invention, the etching rate ratio of the removable template material to the substrate material is preferably >100:1.

[0078] In this invention, the material of the removable template is preferably a green material, more preferably polylactic acid (PLA degradable material) or photoresist, wherein the photoresist is a laser-degradable polymer.

[0079] After obtaining the front cavity structure, the present invention closes the front cavity structure to form a closed cavity, thereby obtaining the functional membrane.

[0080] In this invention, the sealing preferably includes material springback and / or material reflow of the substrate material layer, and more preferably includes applying hot pressure at the opening of the front cavity structure to promote material springback of the substrate material layer. This invention does not specifically limit the parameters of the hot pressure; methods well known to those skilled in the art can be used.

[0081] In this invention, the pre-sealing process preferably includes a directional stretching process to optimize the wall surface of the sealed cavity and avoid surface unevenness that could affect optical efficiency.

[0082] The functional membrane of this invention is an integrally formed closed cavity in a single-layer matrix material layer. The preparation method preferably omits the lamination process, thus eliminating the risk of interface mismatch.

[0083] This utility model also provides the application of the functional film described in the above technical solution or the functional film prepared by the above technical solution in the field of solar cells.

[0084] This utility model also provides a solar cell, including the functional film described in the above technical solution or the functional film prepared by the preparation method described in the above technical solution, for improving the light efficiency of the gap between the solar cell and the battery or / and between the battery and the frame, wherein the functional film serves as an integrated fixing component of the solar cell.

[0085] In the field of solar cells, the functional film of this invention can improve the power generation efficiency, long-term service life and environmental tolerance of solar modules by improving heat dissipation and the structural stability of the encapsulation.

[0086] In this invention, the typical application structure of the functional film in the field of photovoltaic modules preferably includes:

[0087] When the functional film of this invention is applied to a solar cell module, it can serve as an integrated gap film.

[0088] In this invention, the solar cell module preferably includes a stacked structure from top to bottom: tempered glass, an upper encapsulating film, multiple solar cells arranged in parallel, a lower encapsulating film, and a backsheet. The functional film is disposed between two adjacent solar cells, or / and in the gap between the solar cells and the module frame.

[0089] In this invention, the functional film is completely embedded and encapsulated within the encapsulation layer composed of the upper and lower encapsulation films. The substrate material layer of the functional film is preferably the same as or highly compatible with the encapsulation film. After heat lamination, the functional film and the encapsulation film are fused together to form an integral encapsulation structure without obvious interfaces.

[0090] This utility model also provides the application of the functional film described in the above technical solution or the functional film prepared by the above technical solution in the field of light guide display devices.

[0091] In the field of displays, the functional film of this invention can ensure display effect and device life by optimizing heat dissipation, and ensure the stability of optical film function and product durability through structural integrity, thereby improving display quality, extending service life, and promoting thinner and more flexible designs.

[0092] In this invention, the typical application structure of the functional film in the field of light guide display preferably includes:

[0093] When the functional film of this invention is applied to a light guide display device, it can form a novel integrated light guide plate (LGP). The functional film is located in the backlight module of the display, and the functional film is preferably integrated into the backlight module of the display device as a light guide plate.

[0094] This utility model also provides a side-lit backlight module, preferably including a reflective sheet, a light guide plate, a lower diffuser sheet, a prism sheet, and an upper diffuser sheet. An LED light source is also provided on the side of the side-lit backlight module. The light guide plate is the functional film described in this utility model. The functional film itself is used as a light guide plate, replacing the traditional solid acrylic or PC light guide plate.

[0095] This utility model does not have any special limitations on the specific way of application, and any method known to those skilled in the art can be used.

[0096] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0097] Those skilled in the art should understand that the optimal value of the opening size described in the embodiments is closely related to the specific matrix material selected (e.g., its melt viscosity, surface tension, and other thermophysical properties) and the laser process parameters used (e.g., laser power, spot size, scanning speed, pulse width, etc.). Therefore, the 3μm opening size described in this embodiment is only a feasible and preferred example under specific material and process conditions, and should not be construed as the sole limitation on the scope of protection of this utility model. Those skilled in the art can adjust and determine other suitable opening sizes through conventional experimental methods based on different material systems and process equipment used to achieve the integrated closed structure of this utility model.

[0098] Those skilled in the art will understand that the thickness of the substrate material (typical thicknesses include 25, 38, 50, 75, 100, 125, 188, and 250 μm) can significantly affect its effective mechanical properties and its thermodynamic response during localized laser processing. While the inherent material properties (such as chemical composition and glass transition temperature) remain consistent for a given grade of polymer such as PET, variations in film thickness can affect parameters such as flexural stiffness, heat dissipation characteristics, and the distribution of laser-induced thermal stress. For example, thinner films may exhibit greater flexibility but may also be more prone to thermal deformation or have different heat dissipation capabilities compared to thicker films of the same material. Conversely, thicker films possess greater heat capacity, which can alter the temperature gradient achieved during laser irradiation, the size of the molten pool, and the subsequent cooling rate.

[0099] Example 1

[0100] The substrate material is optical grade PET film (model AGO8 PETMO1, purchased from Shanghai Qisheng Electronic Technology Co., Ltd., with TD orientation and refractive index of 1.56), and the removable template is photoresist.

[0101] Preparation steps: (1) Remove the removable template to prepare a front cavity structure with an opening, the opening size of which is 3μm; (2) Material reflow and closure of the front cavity structure: a. Use a focused ultraviolet picosecond laser (wavelength 355nm, pulse width 10ps, repetition frequency 1MHz); b. Control the laser spot size (5μm), scanning speed (100mm / s) and average laser power to make the laser beam scan along the edge of the microchannel opening; c. The PET film undergoes local and rapid melting under laser irradiation, and the molten PET flows under the drive of surface tension and capillary force, bridging and closing the opening. d. After the laser is removed, the molten PET cools and solidifies rapidly, completely fused with the substrate material PET to form a closed cavity, the height of which is 10μm, the distance between the top of the closed cavity and the top of the functional film (i.e., the "top layer" thickness) is 2μm, and the distance between the bottom of the closed cavity and the bottom of the functional film (i.e., the "bottom layer" thickness) is 10μm.

[0102] Results: A closed cavity with an integrated laser fusion sealing structure embedded in a single-layer PET film was obtained. A GRIN layer (gradient layer) was observed in the laser-acted area. The gradient layer has a uniform transition and is caused by local density changes due to the interaction between the laser and the material.

[0103] Figure 1 This is a schematic diagram of a functional membrane structure containing a closed cavity. Figure 2 This is a schematic diagram of the structure of the matrix material layer before reflow.

[0104] Example 2

[0105] The substrate material is an optical-grade POE film with a thickness of 100μm, and the removable template is a photoresist.

[0106] Preparation steps: (1) Remove the removable template to prepare a front cavity structure with an opening, the opening size of which is 3μm; (2) Material springback and material reflow to close the front cavity structure: a. Use a heater array manufactured by microelectromechanical systems technology to apply a pressure of 130℃ (which is higher than the softening point of the POE film but much lower than its rapid degradation temperature) and 0.05MPa to the front cavity structure to assist the contact and flow of the substrate material layer; b. The POE film springs back and reflows under heating (2s) to close the front cavity structure and form a closed cavity.

[0107] Result: A closed cavity embedded in a single-layer POE film was obtained. This embodiment utilizes material rebound to cause rapid contraction of the opening, reducing the gap required for subsequent material reflow. This allows for more complete sealing at a relatively low temperature (130°C) or in a shorter time (2s), and reduces the thermal effects or deformation caused by large-scale reflow. A small auxiliary pressure (0.05MPa) helps ensure tight contact and fusion at the rebound / reflow interface.

[0108] Example 3

[0109] The substrate material is an optical-grade PET film with a thickness of 100 μm (the optical-grade PET film model is AGO8PETMO1, purchased from Shanghai Qisheng Electronic Technology Co., Ltd., and adopts the MD direction). The epitaxial removable template is a PLA degradable material. The elasticity of the PET film in Example 3 is higher than that of the PET film in Example 1.

[0110] Figure 3 This is a schematic diagram of the surface microstructure of the functional membrane before the extensional removable template and the springback area rebound.

[0111] Preparation steps: (1) Remove the epitaxial removable template to prepare a front cavity structure with an opening, the opening size of the front cavity structure is 3μm; (2) Material springback to close the front cavity structure: a. Use a heater array manufactured by microelectromechanical systems technology to apply a heating temperature of 120°C to the front cavity structure. The modified PET film springs back under heating to close the front cavity structure and form a closed cavity.

[0112] Results: A closed cavity embedded in a single-layer PET film was obtained, with its opening sealed by the rebound of the substrate material. At the sealed cavity or its edge, a pre-defined interlocking structure (enhancing the mechanical stability of the seal) was formed due to the guiding effect of the epitaxial removable template, and an optical microstructure was formed. The optical microstructure can be controlled by controlling the structure of the epitaxial region.

[0113] Example 4

[0114] The substrate material is an optical-grade POE film with a thickness of 100 μm, and the removable template is a photoresist, which includes a functional material layer of TiO2.

[0115] Preparation steps: (1) Remove the removable template to prepare a front cavity structure with an opening, the opening size of which is 3μm; (2) Material springback and material reflow to close the front cavity structure: a. Use a heater array manufactured by microelectromechanical systems technology to apply a pressure of 130℃ (which is higher than the softening point of the POE film but much lower than its rapid degradation temperature) and 0.05MPa to the front cavity structure to assist the contact and flow of the substrate material layer; b. The POE film springs back and reflows (10s) under heating to close the front cavity structure and form a closed cavity.

[0116] Figure 4 A schematic diagram of a functional membrane structure including a TiO2 functional material layer as a removable template.

[0117] Results: A closed cavity embedded in a single-layer POE film was obtained, and the functional film includes a functional material layer TiO2.

[0118] Example 5

[0119] The matrix material is a polyolefin elastomer with a thickness of 100 μm.

[0120] Preparation steps: (1) Soluble material (PVA) is embedded in the matrix material layer during the molding process. After the matrix is ​​cured, the soluble material is dissolved to form a front cavity structure with an opening. The opening size of the front cavity structure is 3μm. (2) Material rebound and material reflux to close the front cavity structure: a. Using a heater array manufactured by microelectromechanical systems technology, a pressure of 135℃ (which is higher than the softening point of polyolefin elastomer but much lower than its rapid degradation temperature) and 0.05MPa is applied to the front cavity structure to assist the matrix material layer in contact and flow. b. The polyolefin elastomer rebounds and refluxes (30s) under heating to close the front cavity structure and form a closed cavity.

[0121] Example 6

[0122] A solar cell uses the functional film prepared in Example 1 as an integrated fixing component to improve the light efficiency of the gap between the solar cell and the cell. During the encapsulation process of the solar cell module, the optical functional area of ​​this functional film is placed at the gap position. The closed cavity inside the functional film and the gradient refractive index structure formed around it can effectively redirect sunlight irradiated into the gap area to the effective photosensitive area of ​​the adjacent solar cell through reflection, refraction, or scattering.

[0123] Example 7

[0124] A flexible light guide display device is obtained by integrating the functional film prepared in Example 1 as a light guide film into the backlight module of the display device, thereby obtaining a light guide display device with good thinness and flexibility.

[0125] Comparative Example 1

[0126] The laminated structure forms a film with a closed cavity structure, consisting of two material layers (both optical-grade PET films from Example 1). The two material layers are laminated together to form the laminated structure, and an optically functional cavity is formed at the interface between the two material layers. The cavity height is 10 μm, the distance from the top of the cavity to the top of the film (i.e., the thickness of the "top layer") is 10 μm, and the distance from the bottom of the cavity to the bottom of the film (i.e., the thickness of the "bottom layer") is 10 μm.

[0127] Figure 5 This is a simulated optical transmission diagram of the thin film with a laminated structure in Comparative Example 1. Figure 6 The image shown is a simulation of the optical transmission of the functional film in Embodiment 1 of this utility model. It can be seen that the functional film of this utility model has higher light transmittance and better off-axis performance.

[0128] Luminous flux test results

[0129] Figure 7 The light flux test diagram for the thin film with a laminated structure in Comparative Example 1 shows a minimum light flux of 0, a maximum of 6267.9 W, an average of 237.13 W, a total light flux of 59.283 W, a light flux / emitted light flux ratio of 0.21876, and 298 incident light rays. Figure 8 The luminous flux test diagram for the functional film in Example 1 shows a minimum luminous flux of 0, a maximum of 6267.9 W, an average of 264.42 W, a total luminous flux of 66.106 W, a luminous flux / emitted luminous flux ratio of 0.24393, and 344 incident light rays. It can be seen that the functional film provided by this invention has a higher luminous flux.

[0130] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.

Claims

1. A functional membrane, characterized in that, It includes a base material layer and a closed cavity embedded in the base material layer. The closure of the closed cavity is achieved by forming an integrated sealing structure in situ through the base material layer.

2. The functional membrane according to claim 1, characterized in that, The height of the enclosed cavity is 10–65 μm.

3. The functional membrane according to claim 1 or 2, characterized in that, The geometric forms of the enclosed cavity include protrusions, ridges, recesses, binary forms, inclined forms, square forms, triangular forms, grating pixel forms, trapezoidal forms, or lens forms.

4. The functional membrane according to claim 1, characterized in that, The functional film also includes a gradient refractive index layer.

5. The functional membrane according to claim 1, characterized in that, The surface of the matrix material layer has a microstructure.

6. The functional membrane according to claim 1 or 5, characterized in that, The surface of the substrate material layer is further provided with an additional functional layer, which includes one or more of coatings, films, and surface structures.

7. The functional membrane according to claim 1, characterized in that, The enclosed cavity contains contents, which include fluids and / or solids.

8. The functional membrane according to claim 7, characterized in that, The fluid includes air; the solid includes one or more of temperature-sensitive materials, photosensitizing materials, and functional materials.

9. A solar cell module, characterized in that, The structure includes a top-to-bottom stacked structure: tempered glass, an upper encapsulating film, side-by-side solar cells, a lower encapsulating film, and a backsheet, wherein the functional film according to any one of claims 1 to 8 is disposed between two adjacent solar cells, or / and in the gap between the solar cells and the module frame.

10. A side-lit backlight module, characterized in that, It includes a reflective sheet, a light guide plate, a lower diffuser sheet, a prism sheet, and an upper diffuser sheet, wherein the light guide plate is the functional film described in any one of claims 1 to 8.

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