A black-and-white adhesive layered coating vehicle-mounted high-transparency privacy film and a preparation method thereof

Abstract

The application discloses a black-and-white adhesive layered coating vehicle-mounted high-transmittance anti-peeping film and a preparation method thereof, relates to the technical field of vehicle-mounted display optical films, and aims to solve the problem of light reflection and interference of the front windshield of the vehicle-mounted display screen at night driving in the prior art. The vehicle-mounted high-transmittance anti-peeping film comprises, from the light-in surface to the light-out surface, a modified PET base layer, a first black-and-white adhesive anti-peeping layer, a second black-and-white adhesive anti-peeping layer and a modified PVDF resin weather-resistant protective layer which are sequentially arranged. The application can control light, guide light to the required place and reduce light that may distract the driver's attention, thereby providing a safer driving experience for the driver at night.

Description

Technical Field

[0001] This invention relates to a high-transmittance privacy film for vehicles with black and white adhesive layer coating and its preparation method, belonging to the field of automotive display optical film technology. Background Technology

[0002] In-vehicle displays need to reduce light reflection and interference on the windshield during nighttime driving; however, as in-vehicle displays become larger and are positioned higher on the dashboard, managing reflections becomes increasingly important.

[0003] However, existing black and white adhesive privacy films have three major flaws: Optical performance imbalance: The traditional single-layer black and white adhesive alternating coating grating structure has a light transmittance of only 50-70%. After the brightness enhancement film is superimposed, moiré patterns are generated due to refractive index mismatch, and the brightness drops sharply from the side viewing angle, resulting in a poor viewing experience for the driver and passenger. Insufficient weather resistance: During automotive temperature cycling from -40 to 85°C, the shrinkage rate of ordinary UV adhesive after curing exceeds 3%, causing deformation of the black and white adhesive grating, and a drift of more than ±5° in the privacy viewing angle. After 1000 hours in a dual 85 environment (85°C / 85% RH), the light transmittance decreases by more than 10%. Poor process compatibility: The coating precision of black and white glue is insufficient (±2μm), which easily leads to insufficient gap filling. The mass production yield is only 60%, and it cannot meet the bonding requirements of automotive curved screens. After the black and white glue are coated, the excess glue layer is removed by a scraper process, resulting in poor surface roughness and horizontal lines.

[0004] Although the existing technology uses a black and white adhesive coating design, it has not been modified for weather resistance in the automotive environment, and the optical interference problem of layered coating has not been solved, so it cannot meet the automotive-grade requirements. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-transmittance privacy film for vehicles with black and white adhesive layer coating and its preparation method. By controlling light, guiding light to where it is needed and reducing light that may distract the driver, it provides the driver with a safer driving experience at night.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a high-transmittance privacy film for vehicles with a black and white adhesive layer coating, comprising a modified PET base layer, a first black and white adhesive privacy layer, a second black and white adhesive privacy layer and a modified polyvinylidene fluoride resin weather-resistant protective layer arranged sequentially from the light-incident surface to the light-outceasing surface, wherein the first black and white adhesive privacy layer and the second black and white adhesive privacy layer are staggered.

[0007] Furthermore, the misalignment length between the second black and white adhesive privacy layer and the first black and white adhesive privacy layer ranges from 3 to 5 μm.

[0008] Furthermore, the thickness of the black and white adhesive-coated high-transmittance privacy film for vehicles ranges from 0.30 to 0.50 mm.

[0009] Furthermore, the thickness of the modified PET substrate layer ranges from 110 to 150 μm; the thickness of the first black and white adhesive privacy layer and the second black and white adhesive privacy layer ranges from 40 to 70 μm; and the thickness of the modified PVDF resin weather-resistant protective layer ranges from 80 to 150 μm.

[0010] In a second aspect, the present invention also provides a method for preparing a high-transmittance privacy film for vehicles with a black and white adhesive layer coating as described in any one of the first aspects, comprising: S1. Prepare a modified PET substrate layer; S2. Apply black adhesive to the surface of the modified PET substrate, cure it with ultraviolet light to form a grating, fill the gaps in the grating with white adhesive, and cure it with ultraviolet light again to obtain the first black and white adhesive privacy layer. S3. Repeat S2 under the condition of grating misalignment to obtain the second black and white adhesive privacy layer; S4. Modify the PVDF resin weather-resistant protective layer to obtain a modified polyvinylidene fluoride resin weather-resistant protective layer. S5. The modified polyvinylidene fluoride resin weather-resistant protective layer is bonded to the surface of the second black and white adhesive privacy layer using ultraviolet optical adhesive, to obtain a high-transmittance vehicle privacy film with black and white adhesive layer coating.

[0011] Furthermore, the method for preparing the modified PET substrate layer includes: PET substrate, glass microspheres and antioxidants are melt-blended at 250~330℃, biaxially stretched and then cured by ultraviolet light to obtain a modified PET substrate layer. The glass microspheres constitute 3-5% of the mass of the PET substrate, and the antioxidant constitutes 0.1-0.3% of the mass of the PET substrate. And / or, the antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate; And / or, the parameters for the biaxial stretching molding include longitudinal stretching at 110~120℃ and 120~160 mm / s, and transverse stretching at 120~130℃ and 150~180 mm / s.

[0012] Furthermore, the black glue ingredients include, by weight percentage, 50-80% hydroxyl acrylic resin, 8-12% tannin, 6-10% ferric chloride, 0.1-0.3% UV-327, 2-4% photoinitiator and 16-20% acrylate monomer; The white glue ingredients include, by weight percentage, 3-5% polyurethane acrylate, 3-5% nano titanium dioxide, 4-8% dipropylene glycol diacrylate, 3-6% photoinitiator and 70-90% acrylic resin matrix.

[0013] Furthermore, the UV curing energy range of the black adhesive formulation is 1000~1500mJ / cm². 2 The UV curing energy range of the white glue formulation is 200~500mJ / cm. 2 .

[0014] Furthermore, the width of the grating ranges from 10 to 15 μm, and the width of the grating gap ranges from 30 to 45 μm.

[0015] Furthermore, the preparation method of the modified polyvinylidene fluoride resin weather-resistant protective layer includes: Polyvinylidene fluoride resin and polymethyl methacrylate resin were blended, and silicon-coated rutile nano-titanium dioxide, nano-silica, hindered amine light stabilizer and phosphite antioxidant were added to obtain the protective layer material. The protective layer base film is obtained by melt blending the protective layer material and then casting it into a film. The protective base film was subjected to gradient UV curing treatment to obtain a modified polyvinylidene fluoride resin weather-resistant protective layer.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The staggered distribution design of the dual privacy layers in this invention enables the privacy film to achieve a light transmittance of 80~90% (550nm), which is 20% higher than the traditional solution. The brightness uniformity within ±30° of the privacy viewing angle is ≥92%, with no moiré interference and good anti-reflection effect. Furthermore, the addition of a modified PVDF resin weather-resistant protective layer ensures that the light transmittance decay is ≤2% after 1000 hours of dual 85 testing, there is no grating deformation during cycling from -40 to 85℃, and the privacy viewing angle drift is ≤±1°. The black adhesive of this invention contains UV-327 to improve weather resistance, and the white adhesive contains the flexible monomer TPGDA to make the shrinkage rate ≤1.5%. Furthermore, the curing energy of the black adhesive and the curing energy of the white adhesive are in a gradient form to avoid brittleness caused by over-curing. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a high-transmittance privacy film for vehicles with black and white adhesive layered coating in one embodiment of the present invention; Figure 2 This is a schematic diagram of the anti-reflection effect of a high-transmittance privacy film for vehicles with a black and white adhesive layer coating in one embodiment of the present invention. In this diagram, a is a schematic diagram of the anti-reflection effect of a vehicle display screen without the black and white adhesive layer coating, and b is a schematic diagram of the anti-reflection effect of a vehicle display screen with the black and white adhesive layer coating. In the diagram: 1-PET base layer, 2-first black and white adhesive privacy layer, 3-second black and white adhesive privacy layer, 4-modified polyvinylidene fluoride resin weather-resistant protective layer. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0019] Example 1

[0020] This invention provides a method for preparing a high-transmittance privacy film for vehicles with a black and white adhesive layer coating, comprising the following steps: S1. Polyethylene terephthalate (PET) base resin, 3 wt% glass microspheres and 0.2 wt% antioxidant 1010 are mixed evenly and then fed into a twin-screw extruder. The extruder temperature gradient is set to 270℃→280℃→290℃, the die temperature is 290℃, and melt blending extrusion is carried out under the conditions of screw speed of 250 r / min, material residence time of 6 min and system vacuum degree ≥-0.08MPa to fully remove small molecules and water vapor. Modified PET sheets are obtained by casting. Modified PET sheets are fed into a stretching machine for biaxial stretching. The stretching temperature for longitudinal stretching (MD) is 110-120℃, the stretching speed is 140 mm / s, and the stretching ratio is fixed at 3.0 times. The stretching temperature for transverse stretching (TD) is 125℃, the stretching speed is 165 mm / s, and the stretching ratio is fixed at 3.2 times. The biaxially stretched film was introduced into a heat-setting chamber and heat-set at 185°C and a relaxation rate of 5%. It was then rapidly cooled using a cooling roller at 45°C and cured by ultraviolet radiation to obtain a modified PET substrate layer. The modified PET substrate layer had a thickness of 35 μm and a coefficient of thermal expansion of 27 ppm / °C.

[0021] S2. By mass percentage, the black glue ingredients include: 60.0% hydroxyl acrylic resin, 10.0% tannin, 8.0% ferric chloride, 0.2% UV absorber UV-327, 3.0% photoinitiator 819, and 18.8% acrylate monomer. After uniformly mixing the above black glue components, the mixture is milled using a three-roll mill to a fineness ≤3μm to obtain a black glue coating with an optical density (OD) value of 3.6.

[0022] The black adhesive coating was applied to the surface of a modified PET substrate using a micro-grooving process, and the repeating interval period of the formed black adhesive grating structure was controlled to be 14 μm.

[0023] Subsequently, radiation curing is achieved by dynamically controlling the gradient changes in ultraviolet light intensity, irradiation time, and irradiation distance. During this process, the radiation energy received by the black glue grating layer decreases sequentially from the surface to the bottom layer, thereby guiding the curing degree to decrease layer by layer, ultimately forming a non-uniform gradient cured grating structure with a highly cross-linked and dense surface layer and a moderately flexible bottom layer.

[0024] By weight percentage, the white glue formulation includes: 4.0% polyurethane acrylate, 4.0% nano titanium dioxide, 6.0% dipropylene glycol diacrylate (TPGDA), 4.8% photoinitiator 1173, and 81.2% acrylic resin matrix. The white glue coating was prepared by uniformly grinding the above white glue components using a three-roll mill, and its reflectance was measured to be 89%.

[0025] White glue coating is applied to the gaps of the gradient curing grating. After the excess white glue is squeezed out using a mold, it is cured again with ultraviolet light. Finally, the first black and white glue privacy layer is constructed in the gaps of the grating.

[0026] S3. Repeat S2 under the condition of grating misalignment of 4μm to obtain the second black and white adhesive privacy layer.

[0027] S4. By mass, 70 parts of polyvinylidene fluoride (PVDF) resin and 30 parts of weather-resistant polymethyl methacrylate (PMMA) resin are blended together, and 3 parts of silicon-coated rutile nano-titanium dioxide and 2 parts of nano-silica (SiO2) are introduced into the blend as UV shielding fillers. At the same time, 0.5 parts of hindered amine light stabilizer (UV-944) and 0.3 parts of phosphite antioxidant (antioxidant 626) are added to obtain the protective layer material.

[0028] The above-mentioned protective layer material is fed into a twin-screw extruder for melt blending (feeding section (zone 1): 185-215℃, plasticizing section (zone 2): 205-230℃, homogenizing section (zone 3): 210-240℃, conveying section (zone 4): 215-245℃, die section: 220-250℃), and then the protective layer base film is obtained by casting film forming process.

[0029] Next, a gradient ultraviolet (UV) curing process was adopted (from a light intensity of 500 mW / cm²). 2 Accumulated energy 1000 mJ / cm 2 Divided into three stages, each stage using 200 mJ / cm 2The protective layer base film is subjected to single-sided radiation treatment by increasing the cumulative energy gradient; by controlling the gradient distribution of ultraviolet light radiation intensity and irradiation time, the cross-linking reaction inside the film is guided to decrease layer by layer from the surface to the inner layer, thereby forming a non-uniform gradient structure with dense cross-linking on the surface and flexible transition at the bottom layer inside the protective layer, thus obtaining a weather-resistant protective layer.

[0030] S5. A modified PVDF resin weather-resistant protective layer is bonded to the surface of the second black and white adhesive privacy layer using UV optical adhesive, resulting in a high-transmittance automotive privacy film with layered black and white adhesive coating. Figure 1 As shown.

[0031] Combination Figure 2 The anti-reflective effect of the vehicle screen is effectively improved after the product of Example 1 is applied.

[0032] Comparative Example 1: The only difference between this comparative example and Example 1 is that steps S4 and S5 are omitted.

[0033] Comparative Example 2: The only difference between this comparative example and Example 1 is that, in step S4, the gradient UV curing treatment of the modified PVDF resin weather-resistant protective layer is replaced with a constant UV curing treatment (light intensity 600mW / cm²). 2 Accumulated energy 1200mJ / cm 2 ).

[0034] The performance of the black and white adhesive layered coating automotive high-transmittance privacy films prepared in Example 1, Comparative Examples 1 and 2 was analyzed.

[0035] The specific testing methods are as follows: Transmittance test: A spectrophotometer was used. The test steps included: calibrating the instrument and selecting the transmittance mode; taking an uncoated vehicle display screen as a blank control; attaching the high-transmittance privacy film with black and white adhesive layered onto a standard transparent substrate and placing it in the instrument's measuring hole; setting the test wavelength to 550nm; and taking the average value after three consecutive measurements.

[0036] Privacy viewing angle test: A viewing angle test fixture and a luminance meter are used. The test procedure includes: fixing the high-transmittance automotive privacy film with black and white adhesive layered onto the test fixture, facing the light source. Using the normal (0°) as a reference, slowly rotate the test fixture clockwise / counterclockwise. Observe the changes in brightness / contrast. When the screen contrast drops to 50% or the visibility becomes significantly blurred, stop rotating and record the left and right angles.

[0037] Double 85 Aging (Weather Resistance) Test: A constant temperature and humidity chamber was used. The test procedure included: placing the high-transmittance privacy film with black and white adhesive layered coating into the constant temperature and humidity chamber, setting the temperature to 85℃ and the relative humidity to 85%, and leaving it continuously for 1000 hours. After cooling to room temperature, the transmittance attenuation value was measured, and the calculation expression was as follows: Transmittance attenuation value = (Transmittance before aging - Transmittance after aging) / Transmittance before aging × 100% Scratch resistance hardness test: A pencil hardness tester is used. The test procedure includes: selecting a 3H pencil, sharpening it to expose 2-3mm of lead, and smoothing the end face. Fixing the high-transparency privacy film with black and white adhesive layers on the car screen, with the pencil at a 45° angle to the film surface. Applying a 750g weight, scratching the film 5 times at a uniform speed, and observing the scratches. If there are no obvious dents, no transparency, and no obvious white marks, it is judged to be 3H qualified.

[0038] Test results: The light transmittance of the product in Example 1 reached 88%, and the privacy viewing angle was ±30°; after the double 85 test, the light transmittance decreased by only 1.8%, and the scratch resistance hardness reached 3H. All indicators were qualified.

[0039] Compared with Comparative Example 1, Example 1, by adopting a PVDF protective layer, has a 2-fold increase in UV aging resistance, significantly enhanced salt spray resistance, UV resistance and abrasion resistance, a 75% reduction in film warpage defect rate, and a substantial improvement in product consistency and weather resistance, which can meet the requirements for long-term outdoor use.

[0040] Compared with Comparative Example 2, Example 1 showed improved grating size stability, 42% improved protective layer adhesion, 2 times longer UV aging resistance, and increased production yield from 83% to 94%.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-transmittance privacy film for vehicles with a black and white adhesive layered coating, characterized in that, It includes a modified PET base layer, a first black and white adhesive privacy layer, a second black and white adhesive privacy layer and a modified polyvinylidene fluoride resin weather-resistant protective layer arranged sequentially from the light-incident surface to the light-outceasing surface, wherein the first black and white adhesive privacy layer and the second black and white adhesive privacy layer are staggered.

2. The vehicle-mounted high-transmittance privacy film with black and white adhesive layering as described in claim 1, characterized in that, The misalignment length between the second black and white adhesive privacy layer and the first black and white adhesive privacy layer ranges from 3 to 5 μm.

3. The high-transmittance privacy film for vehicles with black and white adhesive layering as described in claim 1, characterized in that, The thickness range of the black and white adhesive-coated high-transmittance privacy film for vehicles is 0.30~0.50mm.

4. The high-transmittance privacy film for vehicles with black and white adhesive layering as described in claim 3, characterized in that, The thickness of the modified PET substrate layer ranges from 110 to 150 μm; the thickness of the first black and white adhesive privacy layer and the second black and white adhesive privacy layer ranges from 40 to 70 μm. The thickness of the modified polyvinylidene fluoride resin weather-resistant protective layer ranges from 80 to 150 μm.

5. A method for preparing a high-transmittance privacy film for vehicles with a black and white adhesive layered coating as described in any one of claims 1 to 4, characterized in that, include: S1. Prepare a modified PET substrate layer; S2. Apply black adhesive to the surface of the modified PET substrate, cure it with ultraviolet light to form a grating, fill the gaps in the grating with white adhesive, and cure it with ultraviolet light again to obtain the first black and white adhesive privacy layer. S3. Repeat S2 under the condition of grating misalignment to obtain the second black and white adhesive privacy layer; S4. Modify the PVDF resin weather-resistant protective layer to obtain a modified polyvinylidene fluoride resin weather-resistant protective layer. S5. The modified polyvinylidene fluoride resin weather-resistant protective layer is bonded to the surface of the second black and white adhesive privacy layer using ultraviolet optical adhesive, to obtain a high-transmittance vehicle privacy film with black and white adhesive layer coating.

6. The method for preparing a high-transmittance privacy film for vehicles with black and white adhesive layering according to claim 5, characterized in that, The method for preparing the modified PET substrate layer includes: PET substrate, glass microspheres and antioxidants are melt-blended at 250~330℃, biaxially stretched and then cured by ultraviolet light to obtain a modified PET substrate layer. The glass microspheres constitute 3-5% of the mass of the PET substrate, and the antioxidant constitutes 0.1-0.3% of the mass of the PET substrate. And / or, the antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate; And / or, the parameters for the biaxial stretching molding include longitudinal stretching at 110~120℃ and 120~160 mm / s, and transverse stretching at 120~130℃ and 150~180 mm / s.

7. The method for preparing a high-transmittance privacy film for vehicles with black and white adhesive layering according to claim 5, characterized in that, The black glue ingredients include, by weight percentage, 50-80% hydroxyl acrylic resin, 8-12% tannin, 6-10% ferric chloride, 0.1-0.3% UV-327, 2-4% photoinitiator and 16-20% acrylate monomer; The white glue ingredients include, by weight percentage, 3-5% polyurethane acrylate, 3-5% nano titanium dioxide, 4-8% dipropylene glycol diacrylate, 3-6% photoinitiator and 70-90% acrylic resin matrix.

8. The method for preparing a high-transmittance privacy film for vehicles with black and white adhesive layering according to claim 5, characterized in that, The UV curing energy range of the black adhesive ingredients is 1000~1500 mJ / cm². 2 The UV curing energy range of the white glue formulation is 200~500mJ / cm. 2 .

9. The method for preparing a high-transmittance privacy film for vehicles with a black and white adhesive layered coating according to claim 5, characterized in that, The width of the grating ranges from 10 to 15 μm, and the width of the grating gap ranges from 30 to 45 μm.

10. The method for preparing a high-transmittance privacy film for vehicles with black and white adhesive layering according to claim 5, characterized in that, The preparation method of the modified polyvinylidene fluoride resin weather-resistant protective layer includes: Polyvinylidene fluoride resin and polymethyl methacrylate resin were blended, and silicon-coated rutile nano-titanium dioxide, nano-silica, hindered amine light stabilizer and phosphite antioxidant were added to obtain the protective layer material. The protective layer base film is obtained by melt blending the protective layer material and then casting it into a film. The protective base film was subjected to gradient UV curing treatment to obtain a modified polyvinylidene fluoride resin weather-resistant protective layer.

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