Dimmable front windshield glass film integrated with information safety function and preparation method thereof

Abstract

The invention relates to the technical field of automobile equipment manufacturing and information safety, and discloses a dimmable front windshield glass film integrated with an information safety function and a preparation method of the dimmable front windshield glass film. Injecting a peep-proof liquid crystal mixed material between the two layers of PVB films, and laminating to form a mixed film; the peep-proof liquid crystal mixed material comprises a peep-proof material and a liquid crystal material, and the microstructure of the peep-proof material is matched with the liquid crystal molecule arrangement structure of the liquid crystal material; the surface of one PVB film layer of the mixed film is plated with an anode conductive material, the surface of the other PVB film layer is spin-coated with a cathode conductive material, the mixed film is located between the anode conductive material and the cathode conductive material, and the main body film integrating the information safety function and the dimmable function is obtained. The liquid crystal dimming technology and the information safety peep-proof technology are fused, the preparation technology and the electrode and molecule layout mode are optimized, the multifunctional and high-performance main body film is efficiently prepared, the intelligent light regulation and control requirements and data safety protection in rich scenes can be met, and high universality is achieved.

Description

Technical Field

[0001] The present invention relates to the field of automobile equipment manufacturing and information security technology, and in particular to a dimmable front windshield film with integrated information security function and a preparation method thereof. Background Art

[0002] Automotive safety, energy conservation, and environmental protection have become three major research hotspots in the automotive engineering field, both socially and economically significant, and have received significant attention from the industry. With global demands for energy conservation, environmental protection, and safety, the automotive industry is moving towards safety and low energy consumption.

[0003] In automotive equipment, the front windshield must not only meet the needs of light control, but also meet information security challenges. However, existing front windshield films have significant limitations in the following scenarios:

[0004] 1. Highway application scenario: When a vehicle is traveling at high speed, the intensity of sunlight changes rapidly and frequently. The existing film is not responsive enough, which can easily cause temporary blindness to the driver.

[0005] 2. Rural / bumpy road application scenarios: Road vibration and dust can easily cause film structure damage or surface contamination, reducing dimming performance;

[0006] 3. Application scenarios in extreme temperature environments (-30°C to 80°C): Liquid crystal molecular alignment is easily affected by temperature, and electrode stability is poor, resulting in dimming failure;

[0007] 4. Application scenarios for special vehicle models (such as heavy trucks and autonomous vehicles): Heavy trucks have large windshields and need to withstand higher mechanical stresses, and existing films are insufficiently strong. Autonomous vehicles rely on high-transmittance windshields to be compatible with sensors, and existing switchable films have insufficient transmittance (<90%).

[0008] 5. Application scenarios of special-shaped glass: Windshields with curved surfaces or complex structures result in uneven film adhesion and poor dimming effect in the edge areas.

[0009] 6. In nighttime or strong light environment, the screen information inside the car may be seen by outsiders through the dimming film;

[0010] Existing dimmable films mostly use a homogeneous liquid crystal layer structure, which is not optimized for the above-mentioned scenarios and cannot be applied to the above-mentioned scenarios, resulting in problems such as response delay, poor durability, insufficient light transmittance, and privacy information leakage in actual applications. Summary of the Invention

[0011] The present invention aims to provide a dimmable front windshield film with integrated information security function and a preparation method thereof, which integrates liquid crystal dimming technology and information security anti-peeping technology, optimizes the preparation process and layout method, and realizes the efficient preparation of multifunctional and high-performance main film. It can meet the needs of intelligent light control in a variety of scenarios such as highways, extreme environments, special models and special-shaped glass, while enhancing the security protection of data in the car and having strong versatility.

[0012] The basic solution provided by the present invention is: a dimmable front windshield film with integrated information security function and a preparation method thereof, comprising:

[0013] S100, preparing two layers of PVB (polyvinyl butyral) film;

[0014] S200, injecting an anti-privacy liquid crystal mixed material between two layers of PVB film and laminating them together to form a mixed film; wherein the anti-privacy liquid crystal mixed material includes an anti-privacy material and a liquid crystal material, and the microstructure of the anti-privacy material matches the liquid crystal molecular arrangement structure of the liquid crystal material;

[0015] S300: An anode conductive material is plated on the surface of one layer of the PVB film of the hybrid film, and a cathode conductive material is spin-coated on the surface of the other layer of the PVB film. The hybrid film is located between the anode conductive material and the cathode conductive material to obtain a main film with integrated information security functions and dimmable light.

[0016] Furthermore, in S100, the method for preparing the PVB film includes:

[0017] S101, adding hydrochloric acid to the polyvinyl acetate solution for hydrolysis, wherein the mixing ratio of the hydrochloric acid to the polyvinyl acetate solution is 1:1;

[0018] S102, when the hydrolysis reaches a certain degree, adding butyraldehyde in a preset ratio, and controlling the reaction rate and cross-linking density so that the obtained product meets the preset hardness requirement;

[0019] S103, adding water to the product and adjusting the pH value to neutral, leaving it to stand for a preset time, and the precipitated PVB forms a PVB film.

[0020] Furthermore, PVB is precipitated, and a layered casting method is used to apply PVB glue multiple times and solidify it to form a PVB film with an outer film; and nano-silicon dioxide particles are added to the liquid crystal material.

[0021] Furthermore, S200 includes:

[0022] S201, preparing an anti-peeping liquid crystal mixed material;

[0023] S202, applying a preset pressure to inject the anti-peeping liquid crystal mixed material between the two layers of PVB film, and irradiating with ultraviolet light for a preset time;

[0024] S203 , applying a preset pressure in a vacuum environment and maintaining the pressure for a preset time to laminate the two layers of PVB film and the anti-peeping liquid crystal mixed material.

[0025] Furthermore, the anti-peeping material has a prismatic microstructure; the liquid crystal molecules are arranged in a pentagonal honeycomb pattern.

[0026] Furthermore, the liquid crystal material adopts a nematic liquid crystal material or a mixture of a nematic liquid crystal material and a photocurable monomer; polycarbonate and polymethyl methacrylate are used as the base material, and a prismatic microstructure is formed on the surface of the base material using precision manufacturing technology to obtain an anti-peeping material; the anti-peeping material and the liquid crystal material are mixed according to a preset ratio.

[0027] Furthermore, a solution method is used to dissolve the anti-peeping liquid crystal mixed material in chlorobenzene, spin-coat at a preset speed for a preset time, anneal at a preset temperature for a preset time, complete the injection, and simultaneously complete the drying and dehydration of the PVB film.

[0028] Furthermore, in S300, the operation is carried out in an environment where nitrogen is used as a protective gas; indium tin oxide is plated on the edge area of the PVB film by magnetron sputtering to form an edge ring layout, or indium tin oxide is plated on the surface of the PVB film by magnetron sputtering and then the ITO layer is etched away in a preset manner in the central area of its surface to retain the edge ring electrode; zinc oxide sol-gel is spin-coated as the cathode conductive material.

[0029] Furthermore, a nano-hydrophobic coating is added to the surface of the obtained main membrane.

[0030] The present invention is based on a method for preparing a dimmable front windshield film with integrated information security function, and further provides a dimmable front windshield film with integrated information security function, wherein the film is obtained by the above-mentioned preparation method.

[0031] The working principle and advantages of the present invention are as follows: the prepared main film is used on the front windshield of an automobile. In specific applications, the anode conductive material and the cathode conductive material form an electrode layer, which is connected to a control unit comprising a photosensor and a controller. When the light intensity changes, the photosensor generates corresponding electrical signals. The control circuit receives and interprets these signals and adjusts the voltage applied to the electrode layer accordingly. Different voltages lead to different arrangements of liquid crystal molecules, thereby affecting the effect of light passing through the liquid crystal layer. For example, when no current passes through the liquid crystal molecules, the liquid crystal molecules are in an isolated state, perpendicular to the glass surface, allowing light to pass through the front windshield, making the glass appear transparent and allowing a clear view of the scene outside the car window. However, when a voltage passes through the liquid crystal molecules, the voltage drives the liquid crystal molecules to rearrange, causing deviation and forming a certain texture structure, thereby blocking the passage of light. The device dynamically adjusts the liquid crystal molecular alignment in response to changes in light intensity to achieve dimming. The liquid crystal molecules and the privacy-protection microstructure are electrically coupled to form a spatial coupling effect, achieving enhanced performance. In the absence of voltage, the liquid crystal molecules align vertically, matching the tilt angle of the light-transmitting channel with the porous microstructure of the privacy layer. This convex lens diffusion effect widens the viewing angle to over 160°. When medium voltage is applied, the pitch of the liquid crystal helical arrangement resonates with the gradient-index microlens to form a photonic band gap, dynamically adjusting the forward transmittance (60±5%) while simultaneously increasing the attenuation of stray light 30° to 92%. Under high voltage, the liquid crystals align horizontally, triggering the field-induced orientation of the nanowires in the privacy layer, creating a subwavelength grating structure. This dual Brewster angle effect reduces the transmittance at angles greater than 15° to 0.3%, while maintaining 42% visibility in the forward direction. These two factors synergistically increase response speed by 2.3 times (τ = 85ms) and reduce energy consumption by 57%, achieving an adaptive balance between transmittance, viewing angle, and privacy protection.

[0032] Compared with the existing technology, this solution optimizes the preparation method and can achieve significant improvements in multiple key performance aspects in a single preparation process, showing superior comprehensive performance and application potential. By optimizing the electrode structure and the spatial distribution of liquid crystal molecules, the electrical signal is more evenly distributed on the liquid crystal layer, reducing the delay in the transmission of electrical signals and ensuring that each area can quickly respond to voltage changes. The initial orientation and arrangement of the liquid crystal molecules enable them to quickly rearrange when an electric field is applied, enhancing their sensitivity to electric field changes, effectively improving the response speed, and achieving millisecond-level light intensity regulation (<50ms), meeting dynamic scenarios with high requirements for real-time regulation; at the same time, the preparation process is optimized, and through the modification of the functional thin film material, its wear resistance, pollution resistance and temperature change resistance are enhanced, enabling it to operate in complex and harsh environments. It can operate stably in various environments, greatly improving its service life and reliability. In addition, the solution has good compatibility with special scenarios. It is not only adaptable to special-shaped glass and large-size glass, but also meets the stringent requirements of autonomous vehicles for high light transmittance and optical uniformity. In terms of privacy protection, it uses a mixture of anti-peeping materials and liquid crystal materials. While dimming is achieved by precisely controlling the arrangement of liquid crystal molecules, the special structure of the anti-peeping material can achieve an anti-peeping effect, which can effectively limit the lateral viewing angle and prevent outsiders from peeping into the content of the display screen inside the car, thereby improving passenger safety and information confidentiality, and expanding its application prospects in the fields of intelligent transportation and high-end displays.

[0033] It should be emphasized that the reason why the combination of prismatic microstructure and liquid crystal molecules can provide excellent anti-peeping and dimmable functions is that the prismatic microstructure limits light to a specific viewing angle through directional refraction, statically blocking side peeping, while the liquid crystal molecules can dynamically adjust the transmittance or scatter light through voltage. The combination of the two can not only reduce the visible range and blur the side view in anti-peeping mode, but also flexibly switch the transmittance state according to the ambient light, taking into account both privacy protection and adaptive optimization of screen display effects. This combination not only improves the user's privacy protection level, but also enhances the functionality and practicality of the display device.

[0034] In summary, this solution, through process and structural optimization, improves response speed to milliseconds, enhances light intensity regulation, and implements privacy protection, while ensuring high uniformity and stability of the main film. This makes it suitable for complex environments and special scenarios requiring dimming and privacy protection. Furthermore, the optimized design reduces production costs and increases the feasibility of large-scale production. Furthermore, this solution can be combined with touch and sensing technologies to achieve touch and interactive functions, enhancing the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic flow chart of a method for preparing a dimmable front windshield film with integrated information security function provided in the first embodiment of the present invention;

[0036] Figure 2 This is a schematic structural diagram of the main membrane provided in Example 1 of the present invention;

[0037] Figure 3 A schematic diagram of the surface morphology of the nano-hydrophobic coating provided in Example 1 of the present invention;

[0038] Figure 4 This is a schematic structural diagram of the main film provided in Example 1 of the present invention applied on a windshield;

[0039] Figure 5 This is a working principle diagram of the main membrane provided in Example 1 of the present invention;

[0040] The symbols in the drawings of the specification include: PVB film 1, anti-peeping liquid crystal mixed material 2, anode conductive material 3, cathode conductive material 4, and windshield 5. DETAILED DESCRIPTION

[0041] The following is a further detailed description through specific implementation methods:

[0042] Example 1

[0043] Basically as attached Figure 1 and Figure 2 Shown: A method for preparing a dimmable front windshield film with integrated information security function:

[0044] S100, preparing two layers of PVB film 1.

[0045] Specifically, the preparation method of the PVB film 1 includes:

[0046] S101, adding hydrochloric acid to the polyvinyl acetate (PVAc) solution for hydrolysis, wherein the mixing ratio of hydrochloric acid to the polyvinyl acetate (PVAc) solution is 1:1; in this embodiment, 30 ml of PVAc solution and 30 ml of hydrochloric acid can be mixed for reaction to ensure sufficient hydrolysis and generate an intermediate product with moderate viscosity to facilitate subsequent acetalization reaction;

[0047] S102: When the hydrolysis reaches a certain level, a predetermined proportion (10% in this embodiment) of butyraldehyde is added, and the reaction rate and cross-linking density are controlled so that the resulting product meets a predetermined hardness requirement (Shore D60 in this embodiment). This method can achieve both flexibility and impact resistance and is suitable for heavy truck vibration scenarios.

[0048] S103: Water is added to the product and the pH is adjusted to neutral. The product is then allowed to stand for a predetermined time (15 minutes in this embodiment). The precipitated PVB forms a PVB film 1. A neutral environment reduces the precipitation of impurities from the PVB and improves its transparency (up to 92% in this embodiment, meeting the requirements of autonomous driving sensors). In this embodiment, a transparent PVB film 1 (500 mm × 500 mm) with a surface roughness of less than 1 nm is obtained.

[0049] S200, injecting an anti-peeping liquid crystal mixed material 2 between two layers of PVB film 1 and laminating them to form a mixed film; wherein the anti-peeping liquid crystal mixed material 2 includes an anti-peeping material and a liquid crystal material, and the microstructure of the anti-peeping material matches the liquid crystal molecular arrangement structure of the liquid crystal material.

[0050] Specifically, they include:

[0051] S201, prepare an anti-peeping liquid crystal mixed material 2.

[0052] The liquid crystal material may be a nematic liquid crystal material. In this embodiment, the nematic phase 5CB is used, which has good thermal stability and electro-optical effect. It exhibits an ordered but flowing state within a specific temperature range.

[0053] Furthermore, the liquid crystal material is mixed with a photocurable monomer (5% in this embodiment) to balance the curing speed with the degree of freedom of arrangement of the liquid crystal molecules and prevent excessive cross-linking. By mixing the photocurable monomer with the liquid crystal material, photosensitive properties can be introduced while maintaining the liquid crystal properties. This means that the structure and properties of the material can be adjusted by controlling the light exposure. The network structure formed by the polymerization of the photocurable monomer can provide additional mechanical support for the liquid crystal molecules, increasing the stability of the overall material.

[0054] In this embodiment, polycarbonate (PC) and polymethyl methacrylate (PMMA) are used as substrates, and precision manufacturing technology (such as photolithography, electron beam etching or laser processing) is used to form a prismatic microstructure on the surface of the substrate to obtain an anti-peeping material.

[0055] S202, applying a preset pressure (10 MPa in this embodiment), injecting the anti-peeping liquid crystal mixed material 2 between the two layers of PVB film 1, and simultaneously using ultraviolet light (in this embodiment, wavelength 365 nm, intensity 20 mW / cm 2 ) for a preset irradiation time (in this embodiment, 10 seconds).

[0056] In this embodiment, the mixing ratio of the anti-peeping material and the liquid crystal material is 1:10. The solution method is used to dissolve the mixed material in chlorobenzene, and then spin-coated at a preset speed (600 rpm in this embodiment) for a preset time (30 seconds in this embodiment), annealed at a preset temperature (140°C in this embodiment) for a preset time (5 minutes in this embodiment), complete the injection, and simultaneously complete the drying and dehydration of the PVB film 1.

[0057] Ultraviolet curing technology can combine the anti-peeping liquid crystal mixed material 2 and the two layers of PVB film 1, ensuring that the prismatic microstructure of the anti-peeping material matches the pentagonal arrangement of the liquid crystal molecules, and the liquid crystal molecules form a pentagonal honeycomb arrangement; the liquid crystal molecules are arranged in a pentagonal shape, and the pentagonal lattice can disperse stress in a bumpy environment, reduce structural deformation, and improve mechanical stability.

[0058] S203, under a vacuum environment (<0.1Pa), apply a preset pressure (10MPa in this embodiment), maintain the pressure for a preset time (5 minutes in this embodiment), and perform lamination of the two layers of PVB film 1 and the anti-peeping liquid crystal mixed material 2 to eliminate bubbles, ensure uniform distribution of liquid crystal molecules, and avoid local defects with a uniformity deviation of <2%.

[0059] S300, anode conductive material 3 is plated on the surface of one layer of PVB film 1 of the hybrid film, cathode conductive material 4 is spin-coated on the surface of the other layer of PVB film 1, and the hybrid film is located between the anode conductive material 3 and the cathode conductive material 4, thereby obtaining a main body film with integrated information security function and dimmable light, such as Figure 2 shown.

[0060] Specifically, they include:

[0061] In S300 , the cathode conductive material 4 and the anode conductive material 3 are prepared under a nitrogen protective gas environment.

[0062] In this embodiment, a transparent PVB film 1 (500 mm × 500 mm in this embodiment) with a surface roughness of <1 nm is selected; the anode conductive material 3 is indium tin oxide (ITO) material. The two layers of transparent PVB film 1 and the ITO conductive glass substrate are cleaned in isopropyl alcohol for 10 minutes using an ultrasonic cleaner (frequency 40 kHz in this embodiment) and blown dry with nitrogen; an ITO anode with a thickness of 80 nm and a resistance of <10 Ω / sq is plated on the edge area of one layer of the PVB film 1 (width 5 mm in this embodiment) using magnetron sputtering. The edge is arranged in a ring shape, and the center area (diameter 400 mm in this embodiment) remains free of electrode coverage to avoid blocking the driver's line of sight while ensuring uniform distribution of the electric field.

[0063] In this embodiment, zinc oxide (ZnO) sol-gel is spin-coated as the cathode conductive material 4 on the surface of another layer of PVB film 1. The spin-coating thickness is 30 nm, the annealing temperature is 150° C., and the time is 15 minutes to promote sol-gel conversion and form a porous structure to enhance carrier mobility and improve transmission efficiency.

[0064] A nano-hydrophobic coating (contact angle>120°) is added to the surface of the formed main film. The surface morphology of the nano-hydrophobic coating is as follows: Figure 3 As shown, Figure 3 (a) shows the surface morphology of the hydrophobic coating, with a roughness (RMS) of 2.95. Figure 3 (b) is the surface morphology of the single PVB film 1, with an RMS of 3.37. It can be seen from the figure that the addition of a hydrophobic layer reduces the roughness and dust adhesion, making it suitable for dusty environments.

[0065] Based on the above-mentioned method for preparing a dimmable front windshield film with integrated information security function, the prepared main film is used as a front windshield film of a car, thereby obtaining a dimmable front windshield film with integrated information security function; the main film can also be used for other glass or a wider range of application scenarios. Figure 4 FIG. 1 is a schematic diagram of affixing the main body film prepared by the present solution on the front windshield 5 of a car.

[0066] The main film prepared in this embodiment was subjected to a performance test. In the performance test, a 10,000 lux xenon lamp was used to simulate strong light. After the photosensor triggered the current, the time required for the light intensity to drop to 1,000 lux was recorded (<50ms). In the vibration test, the sample was fixed on a vibration table (frequency 20 Hz, amplitude 2 mm) and vibrated continuously for 24 hours. After the test, the transmittance deviation was <1%. An anti-peeping effect test was performed: a light source was used to illuminate the front windshield from different angles, and the transmittance and scattering angle were measured to ensure that the transmittance of the side light was less than 5% and the transmittance of the light directly in front was higher than 90%. The test results show that the anti-peeping function of the present invention can effectively prevent outsiders from peeping into the information inside the car from the side without affecting the line of sight and transmittance directly in front.

[0067] Working principle in specific application: Anode conductive material 3 and cathode conductive material 4 form an electrode layer, which is connected to a control unit. The control unit includes a photosensor and a controller electrically connected to the photosensor. The photosensor can be located close to the side of the liquid crystal panel or directly embedded in the frame. The model of the photosensor should be selected considering its sensitivity, response time and working range, and matching the expected application scenario so as to accurately sense changes in ambient light intensity. Figure 5As shown in the figure, the arrow indicates the direction of light exposure. When the light intensity changes, the photosensor generates corresponding electrical signals. The control circuit receives and interprets these signals and adjusts the voltage applied to the electrode layer accordingly to change the arrangement of the liquid crystal molecules. Different voltages will lead to different alignment of the liquid crystal molecules, thus affecting the effect of light passing through the liquid crystal layer. The entire control unit can integrate feedback mechanisms as needed to ensure that the alignment of the liquid crystal molecules is stable and meets expectations.

[0068] The microstructured optical layer of the privacy-prevention material controls the scattering angle of light, preventing outsiders from viewing the vehicle's interior from the side. The prism-like microstructure scatters or absorbs incident light from the side, ensuring only the light directly in front of it passes through. This makes this windshield film both dimming-resistant and privacy-preventing, ensuring information security.

[0069] A specific dimming application process can be: when a vehicle is traveling at high speed, the sunlight intensity changes rapidly and frequently. According to the Freedericksz transition theory, when the external electric field exceeds the threshold, the liquid crystal molecules begin to deflect. The relationship between the tilt angle θ and the electric field intensity E can be approximated by the following formula:

[0070]

[0071] Where θ is the tilt angle of the liquid crystal molecules, E is the electric field intensity, ∈0 is the vacuum dielectric constant, Δ∈ is the dielectric anisotropy of the liquid crystal, k is the elastic constant, and ∝ indicates a proportional relationship.

[0072] The tilt angle increases with the increase of voltage; when the photosensor is driven at a voltage of 2.5V, the tilt angle of the liquid crystal molecules is 90° and the transmittance is 50%; when the voltage rises to 4V, the angle reaches 120° and the transmittance drops to 10%, blocking strong light.

[0073] When the vehicle enters a tunnel or drives at night, the photosensor disconnects the voltage, the liquid crystal molecules return to their natural arrangement angle of 0-30°, and the glass returns to transparency; when the vehicle is parked in a public place, the system can manually or automatically apply a strong voltage to make the glass opaque, allowing light directly in front to pass smoothly through the prismatic microstructure, ensuring that the driver and passengers' vision is not affected.

[0074] The prismatic microstructure of the privacy-prevention material matches the pentagonal arrangement of the liquid crystal material. Prismatic microstructures are solid-state physical structures with a fixed shape and unchangeable molecular arrangement. Voltage acts only on the liquid crystal layer, altering the molecular arrangement through the electric field, while the prismatic structure remains unresponsive, maintaining its static light-guiding properties. The microprism's light-guiding angle (e.g., ±30°) must be aligned with the orientation of the liquid crystal molecules in transparent mode (e.g., horizontally at 0°). When the liquid crystal molecules are horizontally aligned (transmitting state), light propagates along the prism's preset direction, ensuring clear viewing angles from the forward angle. The symmetry of the pentagonal prism matches the periodicity of the liquid crystal molecular arrangement (e.g., the parallel arrangement of nematic liquid crystals), preventing stray light (e.g., diffraction or scattering) from structural differences in the optical path. When the liquid crystal molecules are tilted (e.g., in the 120° scattering state), their scattered light is still confined by the prism to the preset viewing angle, preventing lateral light leakage. Through experiments, the deviation threshold between the liquid crystal tilt angle and the prism light guide angle is calibrated (for example, when the tilt angle exceeds 15°, the scattered light may overflow the prism limit range), and the upper limit of the tilt angle is set in the driving algorithm to ensure that the dimming function and the anti-peep function work together to prevent outsiders from peeping into the information inside the car.

[0075] The present embodiment provides a dimmable front windshield film with integrated information security function and its preparation method, which has achieved significant improvements in multiple key performance aspects and demonstrated superior comprehensive performance and application potential. By optimizing the electrode structure and the spatial distribution of liquid crystal molecules, the electrical signal is more evenly distributed on the liquid crystal layer, reducing the delay in the transmission of electrical signals and ensuring that each area can quickly respond to voltage changes. The initial orientation and arrangement of the liquid crystal molecules enable them to quickly rearrange when an electric field is applied, enhancing their sensitivity to electric field changes and effectively improving the response speed, achieving millisecond-level light intensity regulation (<50ms), and meeting dynamic scenarios with high requirements for real-time regulation. At the same time, the preparation process is optimized, and the wear resistance, pollution resistance and temperature change resistance of the functional thin film material are enhanced through modification, enabling it to operate in complex and harsh environments. It can operate stably in various environments, greatly improving its service life and reliability. In addition, the solution has good compatibility with special scenarios. It is not only adaptable to special-shaped glass and large-size glass, but also meets the stringent requirements of autonomous vehicles for high light transmittance and optical uniformity. In terms of privacy protection, it uses a mixture of anti-peeping materials and liquid crystal materials. While dimming is achieved by precisely controlling the arrangement of liquid crystal molecules, the special structure of the anti-peeping material can achieve an anti-peeping effect, which can effectively limit the lateral viewing angle and prevent outsiders from peeping into the content of the display screen inside the car, thereby improving passenger safety and information confidentiality, and expanding its application prospects in the fields of intelligent transportation and high-end displays.

[0076] Example 2

[0077] Unlike Example 1, PVB is deposited and a layered casting method is used, with PVB adhesive applied in multiple layers (e.g., three times) (each layer having a thickness of approximately 267 μm) to a total thickness of 800 μm. Each layer is pre-cured at 80°C for 10 minutes and finally cured at 150°C for 30 minutes to form a PVB film 1 with an outer film, achieving a hardness of Shore D65. Nano-silica particles (3%) are then added to the liquid crystal material to enhance impact resistance. The high-pressure lamination parameters are adjusted to 12 MPa, with a holding pressure of 8 minutes to ensure thick film adhesion strength.

[0078] Performance testing was performed using a drop ball test (a 500g steel ball dropped freely from a height of 1m) to impact the film surface, with no cracks or delamination. Light intensity stability test: Under 80,000 lux illumination for 4 hours, the light intensity fluctuation range in the cabin was ±2% (stable at 6,000 lux).

[0079] The present embodiment provides a dimmable front windshield film with integrated information security function and a preparation method thereof, which improves the hardness and strength of the main film and enhances its impact resistance, and is particularly suitable for heavy truck application scenarios.

[0080] Example 3

[0081] Unlike Examples 1 and 2, laser etching is used to remove the ITO layer in the central area (diameter 400 mm) of the surface of a PVB film 1 coated with the anode material ITO, retaining the edge ring electrode. The surface roughness after etching is <2 nm to avoid light scattering. Then, a low birefringence liquid crystal material (Δn = 0.05) is selected to match the refractive index of PVB (1.48) to reduce interface reflection. The thickness of the liquid crystal layer is controlled at 5 μm, and the transmittance is increased to 95%.

[0082] LiDAR compatibility testing: The film was installed on the windshield of an autonomous driving test vehicle, transmitting a 1550nm LiDAR signal. A spectrometer was used to measure the transmitted signal intensity, revealing an attenuation of <1% (compared to the ≈5% attenuation of conventional films).

[0083] This embodiment provides a method for preparing a dimmable front windshield film with integrated information security function. The prepared main film has significantly improved light transmittance and low attenuation rate, and is particularly suitable for autonomous driving vehicles.

[0084] In summary, in different application scenarios, the functional effects of the main film prepared based on the preparation method of this solution and the traditional film are compared as shown in Table 1:

[0085] Table 1 Comparison of the functional effects of the main film prepared by this scheme and the traditional film in different scenarios

[0086] Scenario Traditional film defects Improved effects of the present invention highway Response delay (>200ms) Response time <50ms Heavy truck vibration Film cracking 30% increase in impact resistance Extreme temperatures Failure below -20℃ Operating temperature extended to -30℃-80℃ Special-shaped glass Uneven dimming at the edges (deviation > 15%) Uniformity deviation <5% Anti-peeping function No protection from side peeping The side light transmittance is less than 5%, and the front light transmittance is higher than 90%.

[0087] As can be seen in Table 1, this solution incorporates liquid crystal molecules into PVB film, optimizes the arrangement of the liquid crystal molecules and the position of the electrodes, and applies the resulting film to automotive windshields, enabling intelligent light control on the windshield. Furthermore, by adding a privacy protection feature, it effectively prevents outsiders from viewing the vehicle interior from the side, enhancing privacy protection within the vehicle. This invention not only addresses existing issues with light transmittance, response speed, and environmental adaptability, but also fills a technological gap in privacy protection, offering broad application prospects. This product can also be applied to side windshields and other applications requiring integrated information security and dimming.

[0088] The above is only an embodiment of the present invention. Common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. Ordinary technicians in the relevant field are aware of all common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all existing technologies in the field, and have the ability to apply conventional experimental means before that date. Ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the guidance of this application. Some typical well-known structures or well-known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for preparing a dimmable front windshield film with integrated information security function, characterized in that: include: S100, preparing two layers of PVB film; S200, injecting an anti-peeping liquid crystal mixed material between two layers of PVB film and laminating them to form a mixed film; The anti-peeping liquid crystal hybrid material includes an anti-peeping material and a liquid crystal material, and the microstructure of the anti-peeping material matches the liquid crystal molecular arrangement structure of the liquid crystal material; S300: An anode conductive material is plated on the surface of one layer of the PVB film of the hybrid film, and a cathode conductive material is spin-coated on the surface of the other layer of the PVB film. The hybrid film is located between the anode conductive material and the cathode conductive material to obtain a main film with integrated information security functions and dimmable light.

2. The method for preparing a dimmable front windshield film with integrated information security function according to claim 1, characterized in that: In S100, the method for preparing the PVB film includes: S101, adding hydrochloric acid to the polyvinyl acetate solution for hydrolysis, wherein the mixing ratio of the hydrochloric acid to the polyvinyl acetate solution is 1:1; S102, when the hydrolysis reaches a certain degree, adding butyraldehyde in a preset ratio, and controlling the reaction rate and cross-linking density so that the obtained product meets the preset hardness requirement; S103, adding water to the product and adjusting the pH value to neutral, leaving it to stand for a preset time, and the precipitated PVB forms a PVB film.

3. The method for preparing a dimmable front windshield film with integrated information security function according to claim 2, characterized in that: PVB is precipitated, and the PVB glue is coated multiple times by a layered casting method and solidified to form a PVB film with an outer film; nano-silicon dioxide particles are added to the liquid crystal material.

4. The method for preparing a dimmable front windshield film with integrated information security function according to claim 1, characterized in that: The S200 includes: S201, preparing an anti-peeping liquid crystal mixed material; S202, applying a preset pressure to inject the anti-peeping liquid crystal mixed material between the two layers of PVB film, and irradiating with ultraviolet light for a preset time; S203 , applying a preset pressure in a vacuum environment and maintaining the pressure for a preset time to laminate the two layers of PVB film and the anti-peeping liquid crystal mixed material.

5. The method for preparing a dimmable front windshield film with integrated information security function according to claim 1 or 4, characterized in that: The anti-peeping material has a prismatic microstructure; the liquid crystal molecules are arranged in a pentagonal honeycomb pattern.

6. The method for preparing a dimmable front windshield film with integrated information security function according to claim 1, characterized in that: The liquid crystal material adopts nematic liquid crystal material or a mixture of nematic liquid crystal material and photocurable monomer; polycarbonate and polymethyl methacrylate are used as the base material, and a prismatic microstructure is formed on the surface of the base material using precision manufacturing technology to obtain the anti-peeping material; the anti-peeping material and the liquid crystal material are mixed according to a preset ratio.

7. The method for preparing a dimmable front windshield film with integrated information security function according to claim 6, characterized in that: Using the solution method, the anti-peeping liquid crystal mixed material is dissolved in chlorobenzene, spin-coated at a preset speed for a preset time, annealed at a preset temperature for a preset time, and the injection is completed. The PVB film is dried and dehydrated simultaneously.

8. The method for preparing a dimmable front windshield film with integrated information security function according to claim 1, characterized in that: In S300, the process is performed under a nitrogen protective gas environment; indium tin oxide is plated on the edge area of the PVB film by magnetron sputtering to form an edge ring layout, or indium tin oxide is plated on the surface of the PVB film by magnetron sputtering and then the ITO layer is etched away in a preset manner in the center area of the surface to retain the edge ring electrode; Zinc oxide sol-gel was spin-coated as the cathode conductive material.

9. The method for preparing a dimmable front windshield film with integrated information security function according to claim 1, characterized in that: A nano-hydrophobic coating is added to the surface of the obtained main membrane.

10. A dimmable front windshield film with integrated information security function, characterized in that: The dimmable front windshield film with integrated information security function is obtained by using the preparation method of any one of claims 1 to 9.

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