A kind of vehicle head-up display PVB nano transparent wedge film and preparation method thereof

Abstract

The present invention belongs to the technical field of special functional films, and specifically relates to a vehicle-mounted head-up display PVB nano-transparent wedge film and a preparation method. The wedge angle of the PVB nano-transparent wedge film is 0.3-0.7 mrad; a composite film with an S-polarized light reflection layer-PVB base film layer-light deflection layer structure is formed by a three-layer co-extrusion extrusion; the S-polarized light reflection layer is provided with a nano-transparent coating on the surface away from the PVB base film layer; the front windshield interlayer is used as a vehicle-mounted head-up display, and the first reflection is enhanced by the S-polarized light reflection layer, so that the main virtual image light becomes clear; in the light deflection layer, by adding birefringent crystal powder, a half-wave phase delay can be generated, and the S-polarized light will be converted into P-polarized light. Due to the high transmittance of P-polarized light, the reflection is reduced, thereby reducing the reflectivity of the outer glass, so that the secondary virtual image light formed by the second reflection becomes significantly weaker. Furthermore, the contrast between the main virtual image and the secondary virtual image is enhanced, which is conducive to clear imaging and eliminates the sense of ghosting. The problem that a single wedge film cannot accurately eliminate ghosting is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of special functional films, and in particular relates to a vehicle-mounted head-up display PVB nano-transparent wedge film and a preparation method thereof. Background Art

[0002] Heads-up display (HUD) has been widely used in the automotive field. HUD is also called head-up display system. Its principle is to project relevant data of vehicle driving, such as navigation, vehicle speed data, vehicle control signals, external signal information, etc., directly onto the windshield in front of the driver, so that the driver can easily obtain vehicle data at any time without lowering his head. This can reduce the frequency of the driver looking down at the dashboard, avoid external interference and distraction of the driver's attention, improve reaction speed, and enhance the driving experience.

[0003] In the existing vehicle head-up display system, the front windshield is used as a projection reflector to visualize information on the front windshield. However, since the front windshield is double-layered, the inner glass undergoes the first reflection to form a primary virtual image, and the outer glass undergoes the second reflection, and the light becomes weaker, forming a secondary virtual image. The light reflected by the inner and outer glass layers respectively, due to the difference in glass thickness, the two virtual images cannot overlap, resulting in double images and dizziness.

[0004] In order to solve the ghosting problem, the PVB wedge film is currently used in the interlayer of the windshield. Through the wedge angle of the wedge film, the windshield is made thick at the top and thin at the bottom, so that the reflected image on the inner surface of the glass is almost overlapped with the reflected image on the outer surface of the glass, thereby eliminating the ghosting problem. For example, Chinese invention patents CN116533612B, CN105793033B, CN111417518A, CN110709359A and many other patents disclose the use of wedge-shaped PVB interlayer films in the interlayer of the windshield, which can well solve the ghosting problem of HUD projection.

[0005] However, since the windshield is a curved glass, the wedge film needs to be designed according to each type of glass, and the angle of the wedge film is related to the incident angle of the light, the distance of the virtual image projection and other multiple factors, resulting in the current single wedge film being difficult to fundamentally solve the ghosting problem. And as the requirements for HUD technology become higher and higher, the requirements for imaging clarity and ghosting problems are becoming more and more stringent. The existing wedge film technology is difficult to meet the requirements. Summary of the invention

[0006] In the vehicle head-up display system, the front windshield is used as a projection reflector to visualize information on the front windshield. However, since the front windshield is double-layered, the inner glass undergoes the first reflection to form a main virtual image, and the outer glass undergoes the second reflection, and the light becomes weaker, forming a secondary virtual image. The light reflected by the inner and outer glass layers respectively cannot overlap due to the thickness of the glass and the inner and outer layers, resulting in ghosting. In order to solve the problems of unclear head-up display and dizziness caused by ghosting, the present invention first proposes a vehicle head-up display PVB nano transparent wedge film.

[0007] A vehicle-mounted head-up display PVB nano-transparent wedge film, technically characterized in that: the wedge angle of the PVB nano-transparent wedge film is 0.3-0.7mrad; the PVB nano-transparent wedge film comprises a PVB base film layer, an S-polarized light reflection layer and a light deflection layer; the S-polarized light reflection layer and the light deflection layer are respectively arranged on both sides of the PVB base film layer; the S-polarized light reflection layer is provided with a nano-transparent coating on the surface away from the PVB base film layer; the thickness of the nano-transparent coating is 50-100nm; and the refractive index of the nano-transparent coating is 1.48-1.55.

[0008] Particularly preferably, the nano transparent coating is one of a nano silicon dioxide layer, a nano silicon dioxide and nano glass powder composite layer, and a nano silicon dioxide and nano fluorite composite layer. When the wedge-shaped film is used as an interlayer of a front windshield of an automobile, the nano transparent coating adheres to the inner glass. The nano transparent coating adopts a refractive index close to that of glass to ensure basic light transmittance, and at the same time, it can better reflect S polarized light with the S polarized light reflection layer.

[0009] Particularly preferably, the thickest part of the S-polarized light reflecting layer is 10-15 um.

[0010] Particularly preferably, the light deflection layer is a half-wave plate, and the thickest part thereof is 50-100 um.

[0011] Particularly preferably, the thickest part of the PVB base film layer is 0.76-1.46 mm.

[0012] The present invention further provides a method for preparing a vehicle head-up display PVB nano transparent wedge film, characterized in that the specific preparation method is as follows:

[0013] S1. Preparation of PVB base film material: weigh the raw materials according to weight: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, and 0.05-0.1 parts of antioxidant; add to high-speed mixer, mix well and set aside;

[0014] S2.S Preparation of polarized light reflection layer material: weigh the following raw materials by weight: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, 0.05-0.1 parts of antioxidant, 0.3-0.5 parts of nano zinc oxide, and 0.5-0.8 parts of nano tin oxide; add to high-speed mixer, mix well and set aside;

[0015] S3. Preparation of light deflection layer: Weigh the raw materials in parts by weight: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, 0.05-0.1 parts of antioxidant, 1.5-3.0 parts of birefringent crystal powder; add high mixer, mix well and set aside;

[0016] S4. Add the materials prepared in steps S1, S2, and S3 into a three-layer co-extrusion twin-screw extruder, compound through a T-shaped die head, form a composite film with an S-polarized light reflection layer-PVB base film layer-light deflection layer structure, and then biaxially stretch and shape with a wedge-shaped shaping roller to obtain a wedge-shaped film;

[0017] S5. A nano-transparent coating is applied on the surface of the S-polarized light reflecting layer of the wedge-shaped film prepared in step S4, and the coating is dried and cut to obtain a vehicle-mounted head-up display PVB nano-transparent wedge-shaped film.

[0018] It is particularly preferred that the PVB resin powder in steps S1, S2, and S3 has a hydroxyl content of 16-17wt% and a butyraldehyde content of 77-79wt%. A reasonable proportion of hydroxyl groups will ensure good viscosity of the material, but it should not be too high, otherwise it will cause water absorption, excessive viscosity, and unusable; a reasonable proportion of butyraldehyde groups, i.e., vinyl butyral groups, ensures good thermoplastic processability of the material.

[0019] Particularly preferably, the PVB resin powder in step S1 has a melt index of 3-5 g / 10 min (150° C., load 2.16 kg).

[0020] Particularly preferably, the PVB resin powder in steps S2 and S3 has a melt index of 15-20 g / 10 min (test conditions: 150° C., load: 2.16 kg), because its high thermal flowability ensures the dispersion of the powder.

[0021] Particularly preferably, the plasticizer in steps S1, S2, and S3 is at least one of dipropylene glycol dibenzoate, triethylene glycol diisooctanoate, and triethylene glycol di-n-heptanoate.

[0022] Particularly preferably, the antioxidant in steps S1, S2, and S3 is at least one of antioxidant 1010, antioxidant THP-EPQ, and antioxidant 1098.

[0023] Particularly preferably, the birefringent crystal powder in step S3 is selected from at least one of quartz, mica, and calcite with a particle size of 20-50um. The light deflection layer is prepared by uniformly dispersing birefringent crystals in PVB. By reasonably controlling the film thickness of the light deflection layer, the phase difference between ordinary light (o light) and extraordinary light (e light) is equal to π or an odd multiple, resulting in a half-wave phase delay. If the vibration direction of the incident linear polarized light is at an angle α with the fast axis (or slow axis) of the wave plate, the vibration direction of the outgoing linear polarized light rotates by an angle of 2α toward the direction of the fast axis (or slow axis). Therefore, the incident angle of the S-plate polarized light is reasonably selected, and in the light deflection layer, the S polarized light will be converted into P polarized light. When the angle between the optical axis direction and the optical axis is 45°, the half-wave plate can rotate the polarization direction by twice the angle, that is, 90°, so that the S light becomes P light.

[0024] It is particularly preferred that the three-layer co-extrusion twin-screw extruder in step S4 is three parallel co-rotating twin-screw extruders that hot-melt extrude the PVB base film material, the S-polarized light reflecting layer material, and the light deflection layer material in layers, and overlap them at the die head and compound them through a T-shaped die head, and the extrusion amount of the three is controlled according to the thickness of each layer.

[0025] Particularly preferably, in step S4, the extrusion temperature of the twin-screw extruder is controlled at 165-185°C, and the die temperature is controlled at 130-145°C.

[0026] It is particularly preferred that a wedge-shaped shaping roller is used for shaping in step S4. According to the wedge angle parameter requirements of the wedge-shaped film, an infrared thickness scanner is set at different points to continuously monitor the thickness. The system automatically feeds back the thickness and automatically adjusts the gap between the wedge angle shaping roller and the reducer to ensure that the film thickness is within the tolerance range.

[0027] Particularly preferably, in step S5, the nano transparent coating is applied by radio frequency magnetron sputtering, using SiO2 as a target material to form a uniform, dense, nano silicon dioxide transparent coating with good optical properties.

[0028] Particularly preferably, in step S5, the nano transparent coating is applied by using one or more of liquid acrylic resin, polyurethane resin, silicone resin, and silicone-acrylic resin as film-forming materials, dispersing nano powder in the film-forming material, and forming the nano transparent coating by ultrasonic spraying.

[0029] In the vehicle head-up display system, the front windshield is used as a projection and reflection device. The main reason for the generation of ghosting is that the front windshield is double-layered. The inner glass undergoes the first reflection to form a main virtual image, which cannot overlap with the outer glass for the second reflection of the secondary virtual image. Based on such defects, the present invention provides a vehicle head-up display PVB nano transparent wedge film. First, a wedge film with a wedge angle of 0.3-0.7mrad is provided. The wedge film is in the interlayer of the windshield, and is thick on the top and thin on the bottom. When the projection light reaches the outer glass after the first refraction of the inner glass, the reflection height and angle are changed due to the wedge film, so that the two virtual images reflected by the inner glass and the outer glass of the incident light are close to overlap, thereby reducing the ghosting phenomenon. However, since the windshield is a curved glass, the wedge film needs to be designed according to each type of glass, and the angle of the wedge film is related to the incident angle of the light, the virtual image projection distance, and other multiple factors. It is difficult for a single wedge film to fundamentally solve the ghosting problem. Furthermore, the PVB nano-transparent wedge film of the present invention comprises a PVB base film layer, an S-polarized light reflection layer and a light deflection layer; the S-polarized light reflection layer and the light deflection layer are respectively arranged on both sides of the PVB base film layer; the S-polarized light reflection layer is provided with a nano-transparent coating on the surface away from the PVB base film layer; when the wedge film is used as an interlayer of the front windshield of an automobile, the nano-transparent coating is attached to the inner layer of glass, and the light deflection layer is attached to the outer layer of glass. The nano-transparent coating adopts a refractive index close to that of the glass to ensure basic light transmittance. During projection, the reflectivity of the S-polarized light at an incident angle of 35°-55° for visible light in the 380nm-780nm band exceeds 25%, forming a relatively clear main virtual image. After the light refracts into the glass, it passes through the light deflection layer before reaching the outer glass. The light deflection layer converts the S-polarized light into P-polarized light. The P-polarized light has a high transmittance and a reduced reflection, thereby reducing the reflectivity of the outer glass, so that the secondary virtual image light formed by the second reflection becomes significantly weaker. Therefore, the present invention eliminates the ghosting sensation by enhancing the primary virtual image light reflected for the first time and weakening the secondary virtual image light reflected for the second time, thereby avoiding the problem that a single wedge-shaped film cannot accurately eliminate the ghosting.

[0030] Compared with the prior art, the present invention has the following outstanding features and significant advantages:

[0031] 1. The present invention pre-disperses nano zinc oxide and nano tin oxide in the S polarized light reflecting layer material to form a high refractive index layer, and lays a nano transparent coating as a medium refractive index layer, which better solves the problem of the difficulty in preparing the S polarized light reflecting layer and can better reflect the S polarized light.

[0032] 2. The present invention has a wedge-shaped structure and adds an S-polarized light reflection layer and a light deflection layer. The first reflection is enhanced by the S-polarized light reflection layer, making the main virtual image light clear; in the light deflection layer, by adding birefringent crystal powder, a half-wave phase delay can be generated, and the S-polarized light will be converted into P-polarized light. Since the transmittance of P-polarized light is high, the reflection is reduced, thereby reducing the reflectivity of the outer glass, making the secondary virtual image light formed by the second reflection significantly weaker. Furthermore, the contrast between the main virtual image and the secondary virtual image is enhanced, which is conducive to clear imaging and eliminates the sense of ghosting. The problem that a single wedge-shaped film cannot accurately eliminate ghosting is avoided.

[0033] 3. The present invention forms a composite film of an S-polarized light reflecting layer-PVB base film layer-light deflecting layer structure by extruding three layers at one time, which is easy to control production and easy to mass-produce, and avoids complicated multi-layer coating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to further clarify the technical implementation scheme of the present invention, the present invention is further described below in conjunction with the accompanying drawings:

[0035] Figure 1 This is a schematic structural diagram of a vehicle head-up display PVB nano transparent wedge film of the present invention, wherein 1-PVB base film layer; 2-S polarized light reflection layer; 21-nanometer transparent coating layer; 3-light deflection layer.

[0036] Figure 2 This is a schematic structural diagram of a vehicle head-up display PVB nano transparent wedge film applied to laminated glass of the present invention, wherein 4 is inner glass; 5 is outer glass. DETAILED DESCRIPTION

[0037] The following examples are intended to further describe the implementation process of the technical content of the present invention, but are not intended to limit the scope of protection of the claims of the present invention. If no specific conditions are specified in the examples, they are all carried out according to conventional conditions or process conditions recommended by the manufacturer.

[0038] Example 1

[0039] S1. Preparation of PVB base film material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index is 5g / 10min, hydroxyl content is 17wt%, butyraldehyde content is 79wt%), 25kg of triethylene glycol diisooctanoate, and 0.3kg of antioxidant THP-EPQ; add them into a high-speed mixer and mix them evenly for use;

[0040] S2.S Preparation of polarized light reflection layer material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index is 15g / 10min, hydroxyl content is 17wt%, butyraldehyde content is 79wt%), 25kg of dipropylene glycol dibenzoate, 0.3kg of antioxidant THP-EPQ, 0.3kg of nano zinc oxide, and 0.8kg of nano tin oxide; add them into a high-speed mixer, mix well and set aside;

[0041] S3. Preparation of light deflection layer material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index of 15g / 10min, 17wt% hydroxyl group, 79wt% butyraldehyde group), 25kg of dipropylene glycol dibenzoate, 0.3kg of antioxidant THP-EPQ, and 3kg of quartz powder;

[0042] S4. Add the materials prepared in steps S1, S2, and S3 into a three-layer co-extrusion twin-screw extruder, and the three parallel co-rotating twin-screw extruders hot-melt and layer-extrude the PVB base film material, the S-polarized light reflection layer material, and the light deflection layer material, respectively, and overlap them at the die head and compound them through a T-shaped die head. The extrusion amount of the three is controlled according to the thickness of each layer, and the extrusion temperature of the twin-screw extruder is controlled at 165-185°C, and the die head temperature is controlled at 145°C; through the T-shaped die head compounding, a composite film with a structure of an S-polarized light reflection layer-PVB base film layer-light deflection layer is formed, and after biaxial stretching and wedge-shaped shaping roller shaping, the wedge angle is set to 0.4mrad. According to the wedge angle parameter requirements of the wedge-shaped film, infrared thickness scanners are set at different points to continuously monitor the thickness. The system automatically feeds back the thickness and automatically adjusts the gap between the wedge angle shaping rollers to ensure that the film thickness is within the tolerance range, thereby obtaining a wedge-shaped film;

[0043] S5. The surface of the wedge-shaped film S polarized light reflecting layer prepared in step S4 is subjected to radio frequency magnetron sputtering to form a uniform, dense, optically excellent nano-silicon dioxide transparent coating using SiO2 as a target, and then dried and cut to obtain a vehicle-mounted head-up display PVB nano-transparent wedge-shaped film.

[0044] The above-mentioned technical solution of the vehicle head-up display PVB nano-transparent wedge film adopts three-layer co-extrusion and compounding, which can efficiently and stably set the S-polarized light reflection layer and the light deflection layer on both sides of the PVB base film layer. Figure 1The S-polarized light reflection layer (2) and the light deflection layer (3) are arranged on both sides of the PVB base film layer (1), and a nano transparent coating (21) is arranged on the surface of the S-polarized light reflection layer (2) away from the PVB base film layer (1); nano zinc oxide and nano tin oxide are pre-dispersed in the S-polarized light reflection layer material to form a high refractive index layer, and the nano transparent coating is applied as a medium refractive index layer, which preferably solves the problem that the S-polarized light reflection layer is difficult to prepare, and can better reflect the S-polarized light. The light deflection layer is prepared by uniformly dispersing birefringent crystal powder quartz in the PVB, and by reasonably controlling the film thickness of the light deflection layer, the phase difference between ordinary light (o light) and extraordinary light (e light) is equal to π or an odd multiple, thereby generating a half-wave phase delay. If the vibration direction of the incident linear polarized light is at an angle α to the fast axis (or slow axis) of the wave plate, the vibration direction of the outgoing linear polarized light will rotate by an angle of 2α toward the fast axis (or slow axis). Therefore, by reasonably selecting the incident angle of the S-plate polarized light, the S-polarized light will be converted into P-polarized light in the light deflection layer.

[0045] According to the infrared thickness gauge, measure the thickness at different points and calculate the wedge angle β between the points 1-10 The calculation method of wedge angle β is: thickness difference between points / distance between points, unit: 1mm / 1000mm wedge angle is 1mrad. As shown in Table 1. The wedge angle β is relatively stable.

[0046] Table 1:

[0047]

[0048] Example 2

[0049] S1. Preparation of PVB base film material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index is 3g / 10min, hydroxyl content is 17wt%, butyraldehyde content is 79wt%), 30kg of triethylene glycol diisooctanoate, and 0.3kg of antioxidant THP-EPQ; add them into a high-speed mixer and mix them evenly for use;

[0050] S2.S Preparation of polarized light reflection layer material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index is 15g / 10min, hydroxyl content is 17wt%, butyraldehyde content is 79wt%), 25kg of dipropylene glycol dibenzoate, 0.3kg of antioxidant THP-EPQ, 0.3kg of nano zinc oxide, and 0.8kg of nano tin oxide; add them into a high-speed mixer, mix well and set aside;

[0051] S3. Preparation of light deflection layer material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index of 20g / 10min, 17wt% hydroxyl group, 79wt% butyraldehyde group), 30kg of dipropylene glycol dibenzoate, 0.3kg of antioxidant THP-EPQ, and 3kg of mica powder;

[0052] S4. Add the materials prepared in steps S1, S2, and S3 into a three-layer co-extrusion twin-screw extruder. The three parallel co-rotating twin-screw extruders respectively hot-melt and layer the PVB base film material, the S-polarized light reflecting layer material, and the light deflecting layer material, and then overlap them at the die head and compound them through a T-shaped die head. The extrusion amount of the three is controlled according to the thickness of each layer. The extrusion temperature of the twin-screw extruder is controlled at 165-185° C., and the die head temperature is controlled at 145° C.; through the T-shaped die head compounding, an S-polarized light reflecting layer-PVB base film layer-light deflecting layer is formed. The composite film of the transfer layer structure is biaxially stretched and shaped by a wedge-shaped shaping roller, and the wedge angle is set to 0.4mrad. According to the wedge angle parameter requirements of the wedge-shaped film, an infrared thickness scanner is set at different points to continuously monitor the thickness. The system automatically feeds back the thickness and automatically adjusts the gap between the wedge angle shaping rollers to ensure that the film thickness is within the tolerance range to obtain a wedge-shaped film; the thickest part of the S-polarized light reflection layer is 15um; the light deflection layer is a half-wave plate, and the thickest part is 100um; the thickest part of the PVB base film layer is 1.46mm;

[0053] S5. Compound nano-silicon dioxide and nano-fluorite in a mass ratio of 2:1, disperse them in an acrylic resin emulsion, and use ultrasonic spraying to form a nano-transparent coating with a thickness of 100 nm on the surface of the S-polarized light reflecting layer of the wedge-shaped film prepared in step S4. Dry and cut the coating to obtain a vehicle-mounted head-up display PVB nano-transparent wedge-shaped film.

[0054] As attached Figure 2 The PVB nano-transparent wedge film is used as the interlayer of the front windshield of the automobile, the nano-transparent coating (21) is attached to the inner glass (4), and the light deflection layer (3) is attached to the outer glass (5). In the vehicle-mounted head-up display system, the front windshield is used as a projection reflection device. When the S-polarized light enters the S-polarized light reflection layer at an incident angle of 35°-55°, the reflectivity exceeds 25%, forming a relatively clear main virtual image. After the light refracts into the glass, it passes through the light deflection layer before reaching the outer glass. The light deflection layer is a half-wave plate with a controlled thickness of 50-100um. The light deflection layer converts the S-polarized light into P-polarized light. The P-polarized light has a high transmittance and the reflection is reduced to less than 0.5%, thereby reducing the reflectivity of the outer glass, so that the secondary virtual image light formed by the second reflection is significantly weakened. The main virtual image light is enhanced by the first reflection, and the secondary virtual image light is weakened (difficult to see) by the second reflection, thereby eliminating the sense of ghosting. Compared with the single wedge film structure to solve the ghosting problem, the PVB nano transparent wedge film obtained by this technical solution is clearer when used for head-up display and can adapt to a wider glass room, solving the problem that the wedge film cannot accurately eliminate ghosting.

[0055] Comparative Example 1

[0056] S1. Preparation of PVB base film material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index is 3g / 10min, hydroxyl content is 17wt%, butyraldehyde content is 79wt%), 25kg of triethylene glycol diisooctanoate, and 0.3kg of antioxidant THP-EPQ; add them into a high-speed mixer and mix them evenly for use;

[0057] S2.S Preparation of polarized light reflection layer material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index is 15g / 10min, hydroxyl content is 17wt%, butyraldehyde content is 79wt%), 25kg of dipropylene glycol dibenzoate, 0.3kg of antioxidant THP-EPQ, 0.3kg of nano zinc oxide, and 0.8kg of nano tin oxide; add them into a high-speed mixer, mix well and set aside;

[0058] S3. Preparation of light deflection layer material: weigh the raw materials according to weight: 80kg of PVB resin powder (melt index of 20g / 10min, 17wt% hydroxyl group, 79wt% butyraldehyde group), 25kg of dipropylene glycol dibenzoate, 0.3kg of antioxidant THP-EPQ, and 3kg of mica powder;

[0059] S4. Add the materials prepared in steps S1, S2, and S3 into a three-layer co-extrusion twin-screw extruder. The three parallel co-rotating twin-screw extruders respectively hot-melt and layer the PVB base film material, the S-polarized light reflecting layer material, and the light deflecting layer material, and then overlap them at the die head and compound them through a T-shaped die head. The extrusion amount of the three is controlled according to the thickness of each layer. The extrusion temperature of the twin-screw extruder is controlled at 165-185° C., and the die head temperature is controlled at 145° C.; through the T-shaped die head compounding, an S-polarized light reflecting layer-PVB base film layer-light deflecting layer is formed. The composite film with a transfer layer structure is biaxially stretched and shaped by a wedge-shaped forming roller, and the wedge angle is set to 0.4mrad. According to the wedge angle parameter requirements of the wedge-shaped film, infrared thickness scanners are set at different points to continuously monitor the thickness. The system automatically feeds back the thickness and automatically adjusts the gap between the wedge angle shaping rollers to ensure that the film thickness is within the tolerance range to obtain a wedge-shaped film; the thickest part of the S-polarized light reflection layer is 15um; the light deflection layer is a half-wave plate, and the thickest part is 100um; the thickest part of the PVB base film layer is 1.46mm.

[0060] In this implementation, after the wedge-shaped film was prepared, no nano-transparent layer was applied. The wedge-shaped film was used as the interlayer of the front windshield of the car. When the S-polarized light entered the S-polarized light reflection layer at an incident angle of 35°-55°, the reflectivity was less than 13%, and the main virtual image formed had poor clarity. After the light refracted into the glass, it passed through the light deflection layer before reaching the outer glass. The light deflection layer was a half-wave plate with a controlled thickness of 50-100um. The light deflection layer converted the S-polarized light into P-polarized light. The P-polarized light had high transmittance and reduced reflection, thereby reducing the reflectivity of the outer glass, making the secondary virtual image light formed by the second reflection significantly weaker. The contrast between the main virtual image light reflected for the first time and the secondary virtual image light reflected for the second time was obvious. Although the ghosting was eliminated, the overall clarity decreased.

[0061] The above-mentioned specific preparation and implementation of the PVB nano-transparent wedge film and the interlayer used for the front windshield of the car have been described to explain the principle and positive effect of eliminating the ghosting feeling of the head-up display. Obviously, the PVB nano-transparent wedge film of the present invention has a wedge-shaped structure, and an S-polarized light reflection layer and a light deflection layer are added to enhance the first reflection, so that the main virtual image light becomes clear, and the second reflection is weakened, so that the secondary virtual image is significantly weakened, and the contrast between the main virtual image and the secondary virtual image is enhanced, thereby eliminating the ghosting feeling. The problem that a single wedge film cannot accurately eliminate ghosting is avoided. The composite film with the structure of S-polarized light reflection layer-PVB base film layer-light deflection layer is formed by extruding three layers at a time, which is easy to control production and easy to mass-produce, and avoids complex multi-layer coating process processing. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A vehicle head-up display PVB nano transparent wedge film, characterized in that: The wedge angle of the PVB nano-transparent wedge film is 0.3-0.7 mrad; the PVB nano-transparent wedge film comprises a PVB base film layer, an S-polarized light reflection layer and a light deflection layer; the S-polarized light reflection layer and the light deflection layer are respectively arranged on both sides of the PVB base film layer; the S-polarized light reflection layer is provided with a nano-transparent coating on the surface away from the PVB base film layer; The thickness of the nano transparent coating is 50-100 nm; the refractive index of the nano transparent coating is 1.48-1.55; The raw material composition of the PVB base film layer is as follows: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, and 0.05-0.1 parts of antioxidant. The raw material composition of the S-polarized light reflection layer is as follows: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, 0.05-0.1 parts of antioxidant, 0.3-0.5 parts of nano zinc oxide, and 0.5-0.8 parts of nano tin oxide. The raw material composition of the light deflection layer is as follows: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, 0.05-0.1 parts of antioxidant, and 1.5-3.0 parts of birefringent crystal powder, in parts by weight.

2. The vehicle-mounted head-up display PVB nano-transparent wedge-shaped film according to claim 1, characterized in that: the nano-transparent coating is one of a nano-silicon dioxide layer, a nano-silicon dioxide and nano-glass powder composite layer, and a nano-silicon dioxide and nano-fluorite composite layer.

3. According to claim 1, a vehicle head-up display PVB nano-transparent wedge film is characterized in that: the thickest part of the S-polarized light reflection layer is 10-15um; the light deflection layer is a half-wave plate, the thickest part is 50-100um; the thickest part of the PVB base film layer is 0.76-1.46mm.

4. A method for preparing a vehicle head-up display PVB nano transparent wedge film according to any one of claims 1 to 3, characterized in that: the specific preparation method is as follows: S1. Preparation of PVB base film material: weigh the raw materials according to weight: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, and 0.05-0.1 parts of antioxidant; add to high-speed mixer, mix well and set aside; S2.S Preparation of polarized light reflection layer material: weigh the following raw materials by weight: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, 0.05-0.1 parts of antioxidant, 0.3-0.5 parts of nano zinc oxide, and 0.5-0.8 parts of nano tin oxide; add to high-speed mixer, mix well and set aside; S3. Preparation of light deflection layer: Weigh the raw materials in parts by weight: 80-90 parts of PVB resin powder, 25-35 parts of plasticizer, 0.05-0.1 parts of antioxidant, 1.5-3.0 parts of birefringent crystal powder; add high mixer, mix well and set aside; S4. Add the materials prepared in steps S1, S2, and S3 into a three-layer co-extrusion twin-screw extruder, compound through a T-shaped die head, form a composite film with an S-polarized light reflection layer-PVB base film layer-light deflection layer structure, and then biaxially stretch and shape with a wedge-shaped shaping roller to obtain a wedge-shaped film; S5. A nano-transparent coating is applied on the surface of the S-polarized light reflecting layer of the wedge-shaped film prepared in step S4, and the coating is dried and cut to obtain a vehicle-mounted head-up display PVB nano-transparent wedge-shaped film.

5. The method for preparing a vehicle-mounted head-up display PVB nano-transparent wedge-shaped film according to claim 4, characterized in that: the PVB resin powder in steps S1, S2, and S3 is selected from PVB resin powder with a hydroxyl content of 16-17wt% and a butyraldehyde content of 77-79wt%; the PVB resin powder in step S1 is selected from PVB resin powder with a melt index of 3-5g / 10min; the PVB resin powder in steps S2 and S3 is selected from PVB resin powder with a melt index of 15-20g / 10min.

6. The method for preparing a vehicle head-up display PVB nano-transparent wedge film according to claim 4, characterized in that: the plasticizer in steps S1, S2, and S3 is at least one of dipropylene glycol dibenzoate, triethylene glycol diisooctanoate, and triethylene glycol di-n-heptanoate; the antioxidant is at least one of antioxidant 1010, antioxidant THP-EPQ, and antioxidant 1098.

7. The method for preparing a vehicle head-up display PVB nano transparent wedge film according to claim 4, characterized in that: the birefringent crystal powder in step S3 is selected from at least one of quartz, mica, calcite, and sapphire with a particle size of 20-50 um.

8. The method for preparing a vehicle-mounted head-up display PVB nano-transparent wedge-shaped film according to claim 4, characterized in that: the three-layer co-extrusion twin-screw extruder in step S4 is three parallel co-rotating twin-screw extruders that hot-melt and layer-extrude the PVB base film material, the S-polarized light reflection layer material, and the light deflection layer material respectively, and overlap them at the die head and compound them through a T-shaped die head.

9. The method for preparing a vehicle-mounted head-up display PVB nano-transparent wedge-shaped film according to claim 4, characterized in that: in step S4, a wedge-shaped shaping roller is used for shaping, and according to the wedge angle parameter requirements of the wedge-shaped film, an infrared thickness scanner is set at different points to continuously monitor the thickness, and the system automatically feeds back the thickness and automatically adjusts the gap between the large and small heads of the wedge angle shaping roller.

10. The method for preparing a vehicle head-up display PVB nano-transparent wedge film according to claim 4, characterized in that: in step S5, the nano-transparent coating is applied by radio frequency magnetron sputtering to form a nano-silicon dioxide transparent coating using SiO2 as a target; or one or more of liquid acrylic resin, polyurethane resin, silicone resin, and silicone-acrylic resin are used as film-forming materials, nano-powder is dispersed in the film-forming material, and the nano-transparent coating is formed by ultrasonic spraying.

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