Intelligent light-adjusting vehicle window based on liquid crystal discoloration technology and preparation method thereof

Abstract

The application relates to the technical field of electro-optical functional devices and smart materials, in particular to a smart light-adjusting vehicle window based on liquid crystal color-changing technology and a preparation method thereof. The vehicle window comprises a glass substrate, a transparent conductive layer, a liquid crystal composite material functional layer, a polyvinyl butyral interlayer and a packaging sealing structure. The glass substrate is subjected to chemical toughening treatment and is coated with the transparent conductive layer. A liquid crystal composite prepolymer containing liquid crystals, polymerizable monomers, dichroic dyes and modified nanoparticles is prepared. The prepolymer is coated, film-coated and pre-pressed to form a pre-assembled body. Polymerization is carried out by controlling the temperature and the ultraviolet light intensity in stages to construct a required microstructure. Edge sealing and hot-press laminating integration are carried out. The application solves the technical problem that traditional light-adjusting vehicle windows are difficult to simultaneously have high light transmittance, low haze, fast response and high contrast, the structure is reliable and the smart touch display can be integrated.

Description

Technical Field

[0001] This application relates to the field of electro-optic functional devices and smart materials technology, and in particular to a smart dimming car window based on liquid crystal color-changing technology and its preparation method. Background Technology

[0002] With the booming development of intelligent vehicles and green buildings, people have placed higher demands on intelligent lighting systems that can dynamically adjust the brightness of light. These systems not only need to meet basic functions such as privacy protection and energy conservation and emission reduction, but also need to take into account visual comfort and clarity. As a key component for realizing these functions, the core performance of intelligent dimming windows lies in their internal electro-optical response functional layer.

[0003] Currently, large-area electronically controlled dimming mainly relies on liquid crystal materials, achieved through different polymer-liquid crystal composite structures. One common technique is polymer-dispersed liquid crystal, which disperses liquid crystal in the form of microdroplets within a polymer matrix. By changing the liquid crystal alignment through an electric field, the switching between transparent and hazy states is achieved. The advantages of this method are less visual haziness and faster response in the hazy state; however, its disadvantages are also obvious: in the light-blocking state, the transmittance is still relatively high, resulting in limited light-blocking effect and insufficient contrast between light and dark; furthermore, to achieve a fast response, a higher operating voltage is often required, which not only increases energy consumption but also burdens circuit design.

[0004] Another common technique is polymer-stabilized liquid crystal, which constructs a slight polymer network within the liquid crystal to stabilize the initial alignment of the liquid crystal molecules. This approach typically achieves high contrast and good light-blocking effect; however, because the polymer network itself scatters light, the haze in the transparent state is often high, affecting visual clarity, and its response speed is generally also slow.

[0005] To compensate for the shortcomings of single technologies, the industry has made some attempts at improvement. For example, adding dyes to polymer-dispersed liquid crystals can enhance light blocking, but this often affects the clarity of the transparent state or requires further increases in voltage. Some studies have also tried to optimize the polymer network structure, but these focus on improving a single performance aspect—such as only increasing contrast or only reducing haze. It is difficult to systematically balance multiple indicators such as high light transmittance, low haze, fast response, high contrast, and low voltage in a single-layer function.

[0006] With the advancement of concepts such as smart cockpits, car windows are no longer just light-blocking components, but are gradually becoming intelligent surfaces integrating interactive functions such as touch and display. In existing technologies, the dimming layer and display module are mostly manufactured separately and then integrated through post-lamination or assembly. This can easily lead to problems such as interface reflection, structural thickening, reduced reliability, and optical inconsistencies, making it difficult to achieve a truly smooth, reliable, and integrated smart glass experience.

[0007] Therefore, there is an urgent need for a dimming window solution that can overcome existing limitations at the material and structural levels, synergistically optimize multiple optical and response performances within a single functional layer, and support high-quality and high-reliability integration with intelligent interaction modules. Summary of the Invention

[0008] The purpose of this application is to provide an intelligent dimming car window based on liquid crystal color-changing technology and its manufacturing method, which solves the problem that traditional dimming car windows cannot simultaneously achieve high light transmittance, low haze, fast response and high contrast.

[0009] On one hand, according to embodiments of this application, a smart dimming car window based on liquid crystal color-changing technology is proposed, including:

[0010] The first glass substrate and the second glass substrate are glass substrates that have undergone ion exchange chemical tempering treatment.

[0011] A first transparent conductive layer is bonded to the surface of the first glass substrate facing the second glass substrate;

[0012] A second transparent conductive layer is bonded to the surface of the second glass substrate facing the first glass substrate;

[0013] A first polyvinyl butyral intermediate film covers the surface of the first transparent conductive layer away from the first glass substrate;

[0014] A second polyvinyl butyral intermediate film covers the surface of the second transparent conductive layer away from the second glass substrate;

[0015] The liquid crystal composite functional layer is formed by curing a liquid crystal composite prepolymer between a first polyvinyl butyral intermediate film and a second polyvinyl butyral intermediate film through a two-stage ultraviolet light polymerization process. The microstructure of the cured liquid crystal composite functional layer has the composite characteristics of polymer-dispersed liquid crystal and polymer-stabilized liquid crystal coexisting, including nematic liquid crystal microdroplets dispersed in a flexible chain polymer continuous matrix, and a rigid chain polymer three-dimensional network penetrating the interior of the nematic liquid crystal microdroplets.

[0016] A sealing structure is attached to the periphery of the first glass substrate and the second glass substrate.

[0017] On the other hand, this application proposes a method for manufacturing a smart dimming car window based on liquid crystal color-changing technology, including the following steps:

[0018] S1: Two glass substrates are subjected to ion-exchange chemical tempering treatment, and a transparent conductive layer is formed on a predetermined surface of the glass substrates.

[0019] S2: Formulate a homogeneous liquid crystal composite prepolymer composed of liquid crystal, flexible chain polymerizable monomer, rigid chain polymerizable monomer, photoinitiator, dichroic dye and surface modified nanoparticles.

[0020] S3: On the first glass substrate covered with the first transparent conductive layer, a first polyvinyl butyral intermediate film is covered; the liquid crystal composite prepolymer is coated on the first polyvinyl butyral intermediate film; a second polyvinyl butyral intermediate film is covered on the coated prepolymer; the second glass substrate covered with the second transparent conductive layer is aligned, bonded and pre-pressed with the above-mentioned components to form a pre-assembled body.

[0021] S4: Perform two-stage ultraviolet light polymerization on the pre-assembled body to sequentially initiate the polymerization of the flexible chain polymerizable monomer and the rigid chain polymerizable monomer, and form a liquid crystal composite functional layer with a microstructure of coexistence of polymer dispersed liquid crystal and polymer stable liquid crystal in situ between the first transparent conductive layer and the second transparent conductive layer.

[0022] S5: Perform hot-press lamination on the polymerized components, and then seal the edges of the hot-pressed components.

[0023] In summary, the beneficial technical effects of this application are as follows:

[0024] This application achieves a structural innovation through the coexistence of polymer-dispersed liquid crystal and polymer-stabilized liquid crystal, enabling the dimming car window to exhibit a highly transparent state when not powered on, and to quickly transform into a dark, light-blocking state after being powered on. This simultaneously achieves high light transmittance, low haze, high contrast, and fast response, resolving the performance contradictions of traditional single-technology approaches.

[0025] This application employs a two-stage ultraviolet polymerization process to achieve a stable bond between the functional layer and the substrate; combined with a laminated glass structure and edge sealing, the final product possesses the high strength, impact resistance, weather resistance, and long lifespan characteristics of safety glass.

[0026] The manufacturing process described in this application can pre-install and encapsulate the transparent touch display module inside the interlayer without affecting the main process, achieving a seamless and reliable integration of dimming control and information display, without affecting the overall aesthetics and optical performance of the vehicle window.

[0027] The preparation method of this application has clear steps, well-defined key process parameters, and good repeatability in the production process, which helps to ensure the consistency of product performance and lays a solid foundation for large-scale production. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the steps of a method for preparing an intelligent dimming car window based on liquid crystal color-changing technology, according to an embodiment of this application. Detailed Implementation

[0029] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0031] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0032] In this application, "multiple" means two or more (including two).

[0033] The following is combined with Figure 1 The present application provides a detailed description of an intelligent dimming car window based on liquid crystal color-changing technology and its manufacturing method.

[0034] See appendix Figure 1 This is a flowchart illustrating the steps of a method for preparing an intelligent dimming car window based on liquid crystal color-changing technology, according to an embodiment of this application.

[0035] Example

[0036] This embodiment provides a method for preparing an intelligent dimming car window based on liquid crystal color-changing technology. The specific implementation process is as follows.

[0037] Substrate selection and pretreatment: Two pieces of ultra-clear float glass, each 500mm × 300mm in size and 2.1mm thick, were selected as the substrate materials. They were precision-cut to the required dimensions using CNC machining, and then polished on both sides with cerium oxide polishing powder. Following this, a three-stage cleaning process was performed, using an alkaline cleaning solution with pH=10, deionized water with a resistivity greater than 18 MΩ·cm, and 40 kHz ultrasonic waves. Finally, the surface was dried with dry nitrogen gas to ensure that the cleanliness met the requirements of subsequent coating processes.

[0038] Ion exchange chemical tempering: The cleaned glass is immersed in a molten salt bath with a constant temperature of 400℃ (deviation ±5℃) and a composition of 99.5% potassium nitrate and 0.5% sodium nitrate as a catalyst for 360 minutes; after treatment, the glass is transferred to an annealing furnace preheated to 250℃ and slowly cooled to room temperature.

[0039] Transparent conductive layer deposition: The tempered and cooled glass substrate is fed into a high-vacuum magnetron sputtering coating system. The cavity is evacuated to a base vacuum better than 5.0 × 10⁻⁶. -3 Pa, 99.999% pure argon gas is introduced as the working gas and the pressure is maintained at 0.5 Pa; indium tin oxide ceramic target with a density of not less than 99.9% is used, and reactive sputtering is performed at a substrate temperature of 250±10℃ and a sputtering power of 8 kW to deposit a first transparent conductive layer and a second transparent conductive layer with a thickness of 120±10nm on one main surface of each glass substrate.

[0040] Composite functional film deposition (outer surface of the first glass substrate): Continuing without disrupting the vacuum, the sputtering target is switched to sequentially deposit films on the other outer surface of the first glass substrate, which is designed to face outwards and lacks a transparent conductive layer. Sequential deposition:

[0041] A silica antireflective layer, 80 nm thick (with a deviation of ±5 nm), reduces Fresnel reflection from the glass surface through the principle of destructive interference.

[0042] The silver and titanium dioxide nanocomposite low-emissivity film is co-sputtered using silver and titanium dioxide targets, with a total thickness of approximately 25 nm (deviation ±2 nm). The silver nanoparticles form a conductive network that can efficiently reflect near-infrared light in the 780 nm to 2500 nm wavelength band. The film system design ensures that the average reflectivity in this wavelength band is not less than 85%, thereby achieving heat insulation.

[0043] The cerium oxide-based ultraviolet blocking layer has a thickness of 50 nm (with a deviation of ±5 nm). Cerium oxide is a wide bandgap semiconductor that has strong absorption characteristics for ultraviolet light with wavelengths below 380 nm.

[0044] It should be noted that the iron content (calculated as Fe2O3) of ultra-clear float glass is less than 0.015%, and its inherent high light transmittance is the basis for ensuring the final transparent light effect of the car window.

[0045] Thorough cleaning aims to remove organic contaminants, inorganic particles, and ion residues, and is a key pretreatment to ensure the adhesion of the coating layer and the stability of the functional layer interface.

[0046] In ion-exchange chemical tempering, at high temperatures, sodium ions in the glass surface network diffuse and exchange with potassium ions, which have a higher concentration in the molten salt. Upon cooling, the larger volume of the embedded potassium ions creates a continuous compressive effect on the glass surface, forming a surface compressive stress layer with a depth of approximately 50-70 μm and a compressive stress value exceeding 700 MPa. This layer effectively counteracts the surface tensile stress generated by external loads, increasing the glass's bending strength, impact resistance, and thermal shock resistance several times over, meeting the mechanical performance requirements for safety glass in standards such as GB 9656 "Automotive Safety Glass".

[0047] The transparent conductive layer is an n-type semiconductor transparent conductive oxide. Its high transmittance stems from its wide bandgap and low absorption of visible light; its conductivity comes from the free electrons provided by tin doping. The transparent conductive layer deposited under the specified process parameters is polycrystalline with a low defect density, thus achieving low sheet resistance while ensuring a transmittance of over 90% at 550 nm wavelength. As a planar electrode for applying the driving voltage, the uniformity and low resistance of this layer are crucial for achieving a uniform electric field distribution and reducing energy consumption.

[0048] The low-emissivity film reduces the air conditioning load in the vehicle by reflecting the near-infrared portion of sunlight, thus achieving energy saving; the ultraviolet blocking layer protects the interior of the vehicle, human skin, and the organic components in the liquid crystal composite functional layer of this application from ultraviolet degradation, extending their service life; the anti-reflective layer optimizes the film thickness to cause destructive interference of reflected light of specific wavelengths, thereby improving visual transparency and reducing glare.

[0049] Raw material weighing and functional analysis: In a clean environment with a temperature of 23 ℃ (deviation ±2 ℃) and relative humidity below 30%, use an analytical balance with an accuracy of 0.001 g to accurately weigh the following parts by mass:

[0050] Nematic liquid crystal: 60 parts, selected from nematic mixed liquid crystal with a wide liquid crystal phase temperature range and moderate optical anisotropy;

[0051] Flexible chain polymerizable monomer: 35 parts of polyethylene glycol diacrylate with a number average molecular weight of 400; its long-chain polyethylene glycol structure gives the polymer network flexibility, which is conducive to forming a low-modulus continuous matrix, encapsulating liquid crystal and buffering stress.

[0052] Rigid-chain polymerizable monomer: 5 parts, bisphenol A type epoxy acrylate, whose molecular core is a rigid bisphenol A aromatic ring and whose ends are acrylate reactive groups. After polymerization, it forms a network with high crosslinking density and high modulus, whose main function is to anchor liquid crystal molecules and provide strong orientation constraints.

[0053] Photoinitiator: 0.5 parts, 2-hydroxy-2-methyl-1-phenyl-1-propanone, which cleaves under ultraviolet light to generate active free radicals, initiating the addition polymerization of carbon-carbon double bonds.

[0054] Dichroic dye: The amount added is 5% of the mass of the aforementioned nematic liquid crystal, and a black azo dichroic dye is selected. Its order parameter is greater than 0.7, and the molecules are rod-shaped. In the nematic liquid crystal, its long axis, i.e., the direction of the absorption dipole moment, will be parallel to the director of the liquid crystal molecules. When the electric field changes the direction of the liquid crystal director, the dye molecules rotate synchronously, thereby changing its absorption intensity of visible light; this is the guest-host effect.

[0055] Surface-modified nanoparticles: The amount added is 1.0% of the total mass of the liquid crystal composite prepolymer. They are tungsten oxide nanoparticles modified with silane coupling agent and with an average primary particle size of 25 nm (deviation ±5 nm).

[0056] Mixing and homogenization: Put all the above raw materials into a planetary mixer with a cooling jacket; purge the tank with dry nitrogen to replace the air for 5 minutes, and then seal it; under nitrogen atmosphere, first stir at a revolution speed of 200 r / min and a rotation speed of 50 r / min for 30 minutes to complete macroscopic mixing; then transfer the mixture to the processing chamber of an ultrasonic cell disruptor, and perform pulsed ultrasound treatment (working for 2 seconds, with a 1-second interval) at 30% amplitude under ice-water bath circulation cooling, for a total effective ultrasound time of 30 minutes.

[0057] Vacuum degassing: The ultrasonically treated mixture is transferred into a vacuum degassing device, the pressure is reduced to and maintained at -0.098 MPa, and it is allowed to stand for 40 min (deviation ±5 min). Until no bubbles are observed floating in the liquid and the liquid surface is as calm as a mirror, a homogeneous and transparent liquid crystal composite prepolymer is obtained.

[0058] It should be noted that bisphenol A epoxy acrylate, as a rigid-chain polymerizable monomer, forms a network through polymerization that is the core of the stable liquid crystal region. Its anchoring force originates from the van der Waals forces and steric hindrance effects between the rigid network and the liquid crystal molecules. The order parameter measures the degree of orientational order of dye molecules in the liquid crystal; a higher value indicates better dye-liquidity alignment and higher off-state light absorption efficiency. Surface modification of nanoparticles imbues them with polymerizable olefin bonds, enabling them to participate in the polymerization network, improve the interface, and potentially act as nucleation sites influencing phase separation.

[0059] Planetary stirring provides gentle macroscopic mixing, avoiding localized overheating caused by violent shearing that could trigger prepolymerization; ultrasonic dispersion utilizes the localized extreme high temperature and pressure and strong shock waves generated by the collapse of cavitation bubbles in the liquid, which can effectively dissociate soft and hard agglomerates of nanoparticles, and is one of the most effective means to achieve uniform nanoscale dispersion in low-viscosity prepolymer liquids; ice-water bath cooling is crucial to dissipate the heat generated by ultrasound and prevent temperature rise from triggering thermal polymerization or component volatilization.

[0060] Vacuum static degassing utilizes the principle that dissolved gases in a liquid precipitate out under supersaturation at low pressure, and that existing bubbles rise and burst under pressure difference and buoyancy. Thorough degassing is a crucial pretreatment process to ensure uniform and defect-free subsequent coating layers and a bubble-free final laminated glass product.

[0061] Coating and Applying the First Intermediate Film: The coated first glass substrate is horizontally fixed on the vacuum adsorption stage of the high-precision coating platform, with its first transparent conductive layer facing upwards and adjusted to be horizontal. A transparent polyvinyl butyral intermediate film, pre-cut to the glass size with a nominal thickness of 0.76 mm and corona-treated, is taken as the first intermediate film and slowly laid flat over the first transparent conductive layer from one end to the other, ensuring a smooth and bubble-free fit. Subsequently, the die lip gap of the slit coating head is set to 100 μm and the squeegee angle to 60°; at a constant speed of 0.8 m / min, the prepared liquid crystal composite prepolymer is uniformly coated on the entire surface of the first intermediate film, forming a continuous and smooth liquid film with a wet film thickness of 25 μm (deviation ±2 μm).

[0062] Cover with the second interlayer film: Immediately take a second transparent polyvinyl butyral interlayer film of the same size and slowly lay it flat on the uncured prepolymer liquid film from one end to the other, avoiding the inclusion of large air bubbles.

[0063] It should be noted that the detailed description in this embodiment of using a preferred preparation method with two layers of polyvinyl butyral interlayer to coat the liquid crystal composite prepolymer onto the first transparent conductive layer is key in that an electric field is applied to the liquid crystal composite prepolymer through the first transparent conductive layer. This should be interpreted as covering both methods of directly coating the liquid crystal composite prepolymer onto the surface of the first transparent conductive layer and equivalent methods such as pre-setting other auxiliary layers on the first transparent conductive layer before coating, as in this embodiment. The two-layer interlayer structure of this embodiment provides superior stress buffering and interface protection for the functional layer of the liquid crystal composite material.

[0064] Integrated transparent touch display module: After covering the second layer of polyvinyl butyral intermediate film, a pre-customized thin film electroluminescent transparent display screen (overall thickness 0.3 mm, active area transmittance 85%) is immediately and precisely placed in the predetermined non-viewing window area of ​​the second transparent conductive layer of the second glass substrate (inner substrate), and its ultra-thin flexible ribbon cable is led out from the reserved gap at the edge of the stack.

[0065] Alignment and Pre-compression: Using a robotic arm equipped with a high-resolution camera, the pre-coated second glass substrate is grasped, and its second transparent conductive layer surface is aligned with the underlying polyvinyl butyral interlayer for visual alignment. After alignment, the substrates are stably stacked. The entire stacked structure is moved into a flat-plate vacuum pre-compression machine. After the machine is turned off, a vacuum is first evacuated to -0.08 MPa and held for 3 minutes to initially remove gas. Then, the heating plate is activated to raise the temperature to 85 ℃ (±2 ℃ deviation), while the pressure is slowly applied to 0.6 MPa and held at this pressure for 15 minutes (±2 minutes deviation). After the pressure holding is completed, the pressure is maintained, and the substrate is allowed to cool naturally to below 50 ℃, forming a dense pre-assembled structure.

[0066] It should be noted that slot coating is a precision metering coating technology that uses a pump to precisely deliver liquid, which is then extruded through a slot die to form a film. It offers advantages such as uniform film thickness, neat edges, and high efficiency. The wet film thickness is the main factor determining the final dry film thickness and must be precisely controlled to ensure consistent electric field strength and uniform optical performance.

[0067] Polyvinyl butyral interlayer is a high molecular polymer interlayer for laminated glass. It has extremely high transparency, viscoelasticity, adhesion to glass, and penetration resistance, making it a core material for meeting safety glass regulations.

[0068] Corona treatment introduces polar oxygen-containing groups into the membrane surface through high-voltage discharge, which instantaneously increases its surface energy, improves its wettability to the prepolymer solution, and helps to eliminate interlayer bubbles and establish initial bonding forces.

[0069] This process forms an unpolymerized pre-assembled structure. The vacuum environment facilitates the removal of interlayer gases; heating softens the polyvinyl butyral interlayer, increasing its fluidity and allowing for better filling of microscopic irregularities; pressure promotes close contact between the layers. This pre-compression process aims to obtain a sandwich structure with tight interfaces, no macroscopic bubbles, and fixed relative positions of the layers, providing a stable and well-interfacially contacted "reactor" for subsequent in-situ photopolymerization.

[0070] Atmosphere control: The pre-assembled components are quickly transferred to a closed photocuring reaction chamber containing nitrogen with a purity of ≥99.999% and extremely low water content; nitrogen is continuously introduced for purging, and the oxygen content is monitored in real time by an online oxygen content analyzer until the oxygen concentration in the chamber stabilizes below 0.01% (volume fraction).

[0071] First-stage polymerization: The overall temperature of the pre-assembled assembly is precisely controlled and stabilized at 70℃ (deviation ±1℃) using the heating plates in the reaction chamber. A surface light source of ultraviolet light-emitting diodes with a main peak wavelength of 365 nm is employed, at a power of 40 mW / cm². 2 (deviation ±2mW / cm) 2 The light intensity was used to vertically irradiate the pre-assembled body (incident from the first glass substrate side) for 50 s.

[0072] It should be noted that oxygen is an effective inhibitor of free radical polymerization. It can react with initiator free radicals or chain-growing free radicals to generate inert peroxy free radicals, thereby terminating the polymerization chain. Maintaining an inert atmosphere is a key prerequisite for ensuring that the polymerization reaction proceeds fully and rapidly throughout the entire film depth, avoiding surface stickiness or uneven degree of polymerization.

[0073] The purpose of setting the temperature to 70 °C is to ensure that the system temperature is higher than the clearing point of the nematic liquid crystal used. At this temperature, the liquid crystal is in an isotropic phase, and the liquid crystal molecules and polymerizable monomers are completely miscible, forming a homogeneous solution. Under 365 nm ultraviolet light irradiation, the photoinitiator decomposes to generate free radicals, which mainly initiate rapid free radical polymerization of the flexible polymerizable monomers. As the polymer chains grow and a cross-linked network forms, the entropy of the system decreases, and the free energy changes, leading to thermodynamic polymerization-induced phase separation. The liquid crystals originally dissolved in the monomers are gradually expelled and aggregate to form discrete regions at the nanometer to micrometer scale. Due to the high temperature, the system viscosity is relatively low, and the phase separation kinetics are fast, ultimately forming relatively uniform liquid crystal droplets with an average diameter of about 2 μm. These droplets are encapsulated and fixed by the solidified flexible polymer network, thus forming the basic framework of the polymer-dispersed liquid crystal—that is, liquid crystal droplets dispersed in a continuous polymer matrix.

[0074] Second-stage convergence: After the first-stage irradiation ends, the control system completes two tasks within 3 seconds (deviation ±0.5 seconds):

[0075] The pre-assembled unit's overall temperature is rapidly reduced to 30 ℃ (with a deviation of ±1 ℃) through the integrated forced cooling system within the reaction chamber.

[0076] Simultaneously increase the light intensity of the ultraviolet light source to 80 mW / cm² 2 (deviation ±3 mW / cm) 2 Continue irradiation for 100 seconds under these new conditions.

[0077] Scientific Principles and Process: After the temperature drops to 30 ℃, the system temperature is much lower than the clearing point of the liquid crystal, and the previously formed liquid crystal droplets enter the highly ordered nematic phase. At this point, on a microscopic scale, rigid-chain polymerizable monomers, due to their hydrophobicity and better compatibility with the liquid crystal phase, tend to accumulate inside the formed liquid crystal droplets and at the interface between the liquid crystal droplets and the flexible polymer matrix during and after phase separation. Under higher intensity ultraviolet light irradiation, the bisphenol A type epoxy acrylate monomers in these enriched regions are efficiently initiated to polymerize. Polymerization occurs inside and at the interface of the liquid crystal droplets, thereby generating a through-hole rigid polymer three-dimensional network with a pore size in the range of 500-800 nm within the liquid crystal droplet phase. This rigid network exerts a strong anchoring effect on the liquid crystal molecules inside, firmly fixing the initial alignment direction of the liquid crystal molecules in the absence of an electric field, thus endowing the polymer in this region with the property of stabilizing liquid crystals.

[0078] The final composite structure is formed as follows: Through the two polymerization stages, precisely differentiated and continuously conducted in terms of temperature and light intensity, a continuous matrix composed of a flexible polymer network is ultimately formed in situ between the two transparent conductive layers. Nematic liquid crystal droplets are dispersed within this matrix, and each droplet is internally permeated and stabilized by a rigid three-dimensional polymer network. The two structures are not physically mixed, but rather coexisting composite systems formed by stepwise chemical bonding within the same space. Simultaneously, dichroic dye molecules in the system are anchored within this composite structure, and their absorption direction is coupled to the liquid crystal director.

[0079] Through the above polymerization process, a liquid crystal composite functional layer is formed between the first and second polyvinyl butyral interlayer films. Since the two interlayer films are respectively attached to the first and second transparent conductive layers, the functional layer is actually located within the electric field space constructed by the two transparent conductive layers, and can be driven by the voltage applied to the conductive layers.

[0080] In this composite structure, the dichroic dye molecules are effectively anchored to the liquid crystal molecules through the orientational interaction between their rod-shaped structure and the liquid crystal molecules, and some dye molecules may be anchored to the polymer network through the weak physical interaction between their end groups and the polymer network, ensuring that the direction of their absorption dipole moment is highly coupled with the local liquid crystal director.

[0081] Hot lamination process: The photopolymerized components are placed into the working chamber of a high-pressure autoclave vacuum laminator. The following automatic program is executed:

[0082] Evacuate the cavity to a pressure of -0.1 MPa and maintain for 10 minutes;

[0083] The temperature was programmed to rise to 135 ℃ (deviation ±2 ℃) at a rate of 5 ℃ / min (deviation ±1 ℃ / min), with pressure applied simultaneously during the heating process. The pressure was finally stabilized at 1.2 MPa (deviation ±0.05 MPa) at 135 ℃.

[0084] The pressure and temperature were maintained at 135 ℃ (deviation ±2 ℃) and 1.2 MPa (deviation ±0.05 MPa) for 40 min (deviation ±2 min).

[0085] After the process is completed, the components are slowly cooled to below 50°C at a controlled rate, then the pressure is released and the laminated components are removed.

[0086] Edge sealing: After hot-pressing and cooling, the component is removed. Using a multi-axis dispensing robot, a single-component, low-moisture-permeable epoxy acrylate UV-curing sealant is continuously applied along the glass sides of the component at a constant speed. The sealant line dimensions are controlled to be 1.5 mm in width (tolerance ±0.2 mm) and 0.2 mm in height (tolerance ±0.05 mm). Immediately after application, the component is placed in a high-intensity UV tunnel oven at a peak intensity of 60 mW / cm². 2 (deviation ±5 mW / cm) 2 The product is cured by irradiation under ultraviolet light for 30 seconds, and finally encapsulated to obtain the finished product.

[0087] It should be noted that the thermodynamic driving force for the enrichment of rigid-chain polymerizable monomers in liquid crystal droplets stems from their solubility parameters in the nematic liquid crystal environment being more compatible with the liquid crystal, which leads to their tendency to be distributed into the liquid crystal phase rather than the flexible polymer phase during the polymerization-induced phase separation process.

[0088] Under high temperature and pressure, the polyvinyl butyral interlayer softens and flows, its viscosity drops sharply, and it fully flows and wets the surfaces of the glass and functional layers, forming strong chemical bonds and physical adsorption. This process integrates the polyvinyl butyral interlayer with the upper and lower glass substrates, the intermediate liquid crystal composite functional layer, and the pre-installed transparent touch display module into an inseparable whole with high bonding strength. After this treatment, the component possesses the basic structural properties required for safety glass, such as impact resistance, penetration resistance, and fragment retention.

[0089] Edge sealing aims to permanently encapsulate the sides of laminated glass to prevent the long-term penetration of water vapor and oxygen from the external environment into the interlayer. The intrusion of water vapor and oxygen can cause chemical degradation of organic materials such as liquid crystals and dyes in the functional layers of the liquid crystal composite material, affecting its lifespan and performance. This step is an essential final process to ensure the long-term environmental reliability of the product.

[0090] The intelligent dimming car window prepared in this embodiment operates in a normal white mode. Its core mechanism lies in the unique microstructure of the liquid crystal composite material functional layer and its synergistic effect with dichroic dyes.

[0091] Power-off transparent state (normal white): When no driving voltage is applied between the first and second transparent conductive layers, due to the strong anchoring effect of the rigid polymer three-dimensional network penetrating the interior of the liquid crystal microdroplet, the nematic liquid crystal molecules and the dichroic dye molecules dissolved within the microdroplet are all fixed in a uniform preferred orientation. In this state, when incident visible light passes through the liquid crystal microdroplet, the birefringence effect of the liquid crystal molecules is minimized, and the absorption of light by the dye molecules is also weakest, thus allowing light to pass through efficiently, exhibiting a transparent state with high transmittance and low haze.

[0092] Darkening State (Dimming): When a specific AC driving voltage is applied between two transparent conductive layers, the resulting strong electric field overcomes the anchoring force of the rigid polymer network, forcing the liquid crystal molecules within the liquid crystal droplets to collectively orient themselves, aligning their long axes along the direction of the electric field. Due to the guest-host effect, the absorption dipole moment of the dichroic dye molecules dissolved in the liquid crystal will synchronously rotate with the liquid crystal molecules. This large-angle change in the absorption direction of the dye molecules leads to a sharp increase in their absorption intensity of incident visible light. At this point, the car window macroscopically transforms into a dark-colored, low-transmittance light-blocking state.

[0093] The polymer-dispersed liquid crystal and polymer-stabilized liquid crystal coexistence structure of this invention provides an optimized basis for the above process. The flexible polymer continuous matrix ensures the uniform dispersion and rapid response potential of the liquid crystal droplets; while the internal rigid polymer network precisely controls the initial alignment of the liquid crystal / dye when power is off and provides appropriate elastic recovery force when power is applied. The introduction of modified nanoparticles further improves network uniformity and electro-optic properties. Therefore, this structure successfully synergistically achieves high transmittance, low haze, high contrast, and rapid response.

[0094] The obtained car window samples were tested according to relevant standards:

[0095] Optical performance: The spectral transmittance was measured using a spectrophotometer with an integrating sphere in the unvoltaged state (transparent state) and the state with an applied voltage of 24 V and 1 kHz (dark state). The results showed that the average transmittance of the transparent state in the visible light range was 84% ​​(deviation ±1%), and the haze was 1.5% (deviation ±0.3%). The average transmittance of the dark state was 6.5% (deviation ±0.5%).

[0096] Electro-optic response time: Using a square wave voltage drive (0 V-24 V, 1 kHz), the light intensity change curve was recorded using a high-speed photodetector and a digital storage oscilloscope; the on-state response time from transparent to dark state was measured to be 8 ms (deviation ±1 ms), and the off-state response time from dark state back to transparent state was 12 ms (deviation ±2 ms).

[0097] Reliability testing: After passing high temperature and high humidity storage and cold and heat cycling tests, the main optical performance degradation was less than 5%, and there were no appearance defects such as delamination, bubbles, or discoloration.

[0098] Touch display function: The integrated transparent display screen displays normally after being powered on. The touch sensor sensitivity meets the design specifications and can be linked with the dimming drive circuit to realize functions such as touch adjustment of light transmittance.

[0099] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing an intelligent dimming car window based on liquid crystal color-changing technology, characterized in that, Includes the following steps: S1: Two glass substrates are subjected to ion-exchange chemical tempering treatment, and a transparent conductive layer is formed on a predetermined surface of the glass substrates. S2: Formulate a homogeneous liquid crystal composite prepolymer composed of liquid crystal, flexible chain polymerizable monomer, rigid chain polymerizable monomer, photoinitiator, dichroic dye and surface modified nanoparticles; S3: On a first glass substrate covered with a first transparent conductive layer, a first polyvinyl butyral intermediate film is covered on the surface of the first transparent conductive layer away from the first glass substrate; a liquid crystal composite prepolymer is coated on the first polyvinyl butyral intermediate film; a second polyvinyl butyral intermediate film is covered on the coated prepolymer; the second glass substrate covered with the second transparent conductive layer is aligned, bonded and pre-pressed with the above-mentioned components to form a pre-assembled body, wherein the second polyvinyl butyral intermediate film is located on the surface of the second transparent conductive layer away from the second glass substrate; S4: Perform two-stage ultraviolet light polymerization on the pre-assembled body to sequentially initiate the polymerization of the flexible chain polymerizable monomer and the rigid chain polymerizable monomer, and form a liquid crystal composite functional layer with a microstructure of coexistence of polymer dispersed liquid crystal and polymer stable liquid crystal in situ between the first transparent conductive layer and the second transparent conductive layer. S5: Perform hot-press lamination on the polymerized components, and then seal the edges of the hot-press laminated components. Step S4 includes: The pre-assembled body was subjected to two-stage ultraviolet light polymerization under an inert atmosphere, wherein: In the first stage, the flexible chain polymerizable monomer is irradiated with ultraviolet light with a center wavelength of 365nm and a light intensity of 30 mW / cm² to 50 mW / cm² at a temperature of 60°C to 80°C to initiate the polymerization of the polymerizable monomer and form a continuous polymer matrix containing liquid crystal microdroplets. In the second stage, at a temperature of 20°C to 40°C, ultraviolet light with a center wavelength of 365nm and a light intensity of 70 mW / cm² to 100 mW / cm² is used to irradiate the liquid crystal microdroplets to initiate the polymerization of the rigid chain polymerizable monomers inside the liquid crystal microdroplets and at the interface between the liquid crystal microdroplets and the polymer continuous matrix, forming a rigid polymer three-dimensional network that runs through the liquid crystal microdroplets. Through the first and second stages, a liquid crystal composite functional layer in which polymer-dispersed liquid crystal and polymer-stabilized liquid crystal coexist is formed in situ between the first and second transparent conductive layers.

2. The method for preparing an intelligent dimming car window based on liquid crystal color-changing technology according to claim 1, characterized in that, Step S1 includes: Two ultra-white float glass substrates were subjected to ion exchange chemical tempering treatment to form a compressive stress layer on the surface of the glass substrates. An indium tin oxide transparent conductive layer is deposited on the inner surface of the glass substrate using a magnetron sputtering process; An anti-reflection film, a low-emissivity film, and an ultraviolet blocking film are sequentially deposited on the outer surface of the first glass substrate to form a composite functional film. The low-emissivity film reflects near-infrared light.

3. The method for preparing an intelligent dimming car window based on liquid crystal color-changing technology according to claim 1, characterized in that, Step S2 includes: By weight, weigh out 55 to 65 parts of nematic liquid crystal, 30 to 40 parts of polyethylene glycol diacrylate, 3 to 8 parts of bisphenol A epoxy acrylate and 0.3 to 1.0 parts of photoinitiator, and mix them to form a basic mixture; Azo dichroic dyes and surface-modified nanoparticles are added to the base mixture, wherein: The amount of the azo dichroic dye added is 3% to 8% of the mass of the nematic liquid crystal; The amount of the surface-modified nanoparticles added is 0.5% to 2.0% of the total mass of the base mixture; Under an inert atmosphere, all materials are mechanically stirred and ultrasonically dispersed, and then degassed under vacuum to obtain a liquid crystal composite prepolymer.

4. The method for preparing an intelligent dimming car window based on liquid crystal color-changing technology according to claim 1, characterized in that, Step S3 includes: The liquid crystal composite prepolymer is coated with a wet film thickness of 20 μm to 30 μm onto the first layer of polyvinyl butyral intermediate film that is pre-covered on the first transparent conductive layer using a slit coating process. A polyvinyl butyral interlayer with a thickness of 0.38 mm to 0.76 mm is used to cover the surface coated with the liquid crystal composite prepolymer. The second glass substrate having the second transparent conductive layer and the first glass substrate carrying the liquid crystal composite prepolymer and the intermediate film are aligned and bonded in a vacuum environment. The aligned and bonded components are pre-compressed under a temperature of 80°C to 100°C and a pressure of 0.5MPa to 0.8MPa to allow the layers to initially bond and remove interlayer air bubbles, thus forming the pre-assembled body.

5. The method for preparing an intelligent dimming car window based on liquid crystal color-changing technology according to claim 1, characterized in that: The inert atmosphere is a nitrogen atmosphere with an oxygen content of no more than 0.1%; the first stage polymerization and the second stage polymerization are carried out continuously, and the switching time between the two stages is less than 5 seconds.

6. The method for preparing an intelligent dimming car window based on liquid crystal color-changing technology according to claim 1, characterized in that, Step S5 includes: The polymerized component is placed in a vacuum laminator and subjected to hot lamination at a temperature of 120°C to 140°C and a pressure of 0.8MPa to 1.2MPa to soften and flow the polyvinyl butyral interlayer and firmly bond it to the adjacent layers. UV-curable sealant is applied to the edges of the hot-pressed components and then cured by UV light.

7. A smart dimming car window based on liquid crystal color-changing technology prepared using the preparation method described in claim 1, characterized in that, include: The first glass substrate and the second glass substrate are glass substrates that have undergone ion exchange chemical tempering treatment. A first transparent conductive layer is bonded to the surface of the first glass substrate facing the second glass substrate; A second transparent conductive layer is bonded to the surface of the second glass substrate facing the first glass substrate; A first polyvinyl butyral intermediate film covers the surface of the first transparent conductive layer away from the first glass substrate; A second polyvinyl butyral intermediate film covers the surface of the second transparent conductive layer away from the second glass substrate; The liquid crystal composite functional layer is formed by curing a liquid crystal composite prepolymer between a first polyvinyl butyral intermediate film and a second polyvinyl butyral intermediate film through a two-stage ultraviolet light polymerization process. The microstructure of the cured liquid crystal composite functional layer has the composite characteristics of polymer-dispersed liquid crystal and polymer-stabilized liquid crystal coexisting, including nematic liquid crystal microdroplets dispersed in a flexible chain polymer continuous matrix, and a rigid chain polymer three-dimensional network penetrating the interior of the nematic liquid crystal microdroplets. A sealing structure is attached to the periphery of the first glass substrate and the second glass substrate.

8. The intelligent dimming car window based on liquid crystal color-changing technology according to claim 7, characterized in that: The functional layer of the liquid crystal composite material is in a normally white mode; When no driving voltage is applied between the first transparent conductive layer and the second transparent conductive layer, the liquid crystal composite functional layer is transparent, with a visible light transmittance of not less than 82% and a haze of less than 2%. When a driving voltage is applied between the first transparent conductive layer and the second transparent conductive layer, the liquid crystal composite material functional layer transforms into a dark state with a light transmittance of no more than 8%.

9. The intelligent dimming car window based on liquid crystal color-changing technology according to claim 7, characterized in that: It also includes an integrated transparent touch display module; the integrated transparent touch display module is a thin-film electroluminescent transparent display screen, which is attached to the surface of the second transparent conductive layer away from the second glass substrate and is located between the second transparent conductive layer and the second polyvinyl butyral intermediate film; the transparent touch display module is bonded to the adjacent layer by softening and bonding the second polyvinyl butyral intermediate film during hot pressing.

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