Optical film, decorative film, and electronic device

Abstract

The application belongs to the technical field of film materials, and relates to an optical film, a decorative film and an electronic device.The optical film comprises a color layer, and the color layer comprises a high-refractive-index layer and a low-refractive-index layer which are sequentially stacked; the refractive index of the high-refractive-index layer is 2.1-2.5, the band gap width of the material of the high-refractive-index layer is greater than or equal to 3.5eV; and the refractive index of the low-refractive-index layer is 1.45-1.55.The color layer of the application realizes more uniform and stable color development effect through an optical interference effect, improves optical stability, avoids problems such as discoloration and color deviation in a long-term use process, guarantees the color development effect of the optical film, controls the band gap width range of the material of the high-refractive-index layer, can absorb ultraviolet and convert it into heat energy, the high-refractive-index layer has a certain scattering effect on ultraviolet, absorption and scattering cooperation can effectively block ultraviolet penetration, greatly improves the ultraviolet aging resistance of the film layer, and effectively solves the discoloration problem of the optical film under long-time irradiation of the sun.

Description

Technical Field

[0001] This invention belongs to the field of membrane material technology and relates to an optical film, a decorative film, and an electronic device. Background Technology

[0002] Currently, optical films based on polyethylene terephthalate (PET) and polycarbonate (PC) are widely used in consumer electronics and automotive exterior decoration. The industry's conventional film structure is film substrate - brushed texture layer - single-layer electroplated color layer - protective ink layer.

[0003] In existing optical films prepared using evaporation deposition technology, the color layer employs alternating stacks of silicon dioxide and titanium dioxide (TiO2) to enhance the color texture of the optical film. However, the UV aging resistance of titanium dioxide remains insufficient. Under long-term ultraviolet irradiation, photocatalytic reactions easily occur, leading to film surface degradation and discoloration, severely affecting the product's appearance, lifespan, and reliability. In summary, existing optical films generally suffer from weak UV aging resistance, and the industry urgently needs an optical film with superior UV aging resistance. Summary of the Invention

[0004] The main objective of this invention is to overcome the deficiencies in the prior art and provide an optical film, a decorative film, and an electronic device.

[0005] To achieve the above objectives, the specific technical solution is as follows: This invention provides an optical film, including a color layer, wherein the color layer comprises a high refractive index layer and a low refractive index layer stacked sequentially; The high refractive index layer has a refractive index of 2.1-2.5 and a band gap width of ≥3.5eV; the low refractive index layer has a refractive index of 1.45-1.55.

[0006] Furthermore, the material of the high refractive index layer is independently selected from any one of lanthanide metal oxyacid salts and rare high-melting-point binary metal oxides.

[0007] Furthermore, the lanthanide metal oxyacid salt is selected from any one of lanthanum disitinitate, lanthanum niobate, and lanthanum yttrium oxide; the rare high-melting-point binary metal oxide is selected from hafnium oxide or scandium oxide.

[0008] In one specific embodiment of the present invention, the material of the high refractive index layer is selected from lanthanum disitinoate.

[0009] Furthermore, the total thickness of the color layer is 50-300 nm, and the thickness of the low refractive index layer and the high refractive index layer are each independently 10-130 nm.

[0010] In one specific embodiment of the present invention, the optical film is yellow-green, and the color layer is a lanthanum distitanate layer, a silicon dioxide layer and a lanthanum distitanate layer stacked sequentially.

[0011] The present invention also provides a decorative film comprising a shielding layer, the aforementioned optical film, a textured layer, and a substrate stacked sequentially.

[0012] Furthermore, the optical film also includes a first transition layer; the first transition layer is disposed on the side of the color layer near the texture layer, and the material of the first transition layer is a mixture of silicon dioxide and aluminum oxide; preferably, the thickness of the first transition layer is 5-15 nm.

[0013] Furthermore, the mass ratio of aluminum oxide to silicon dioxide is (1-3):(17-19).

[0014] Furthermore, the optical film also includes a second transition layer, which is disposed on the side of the color layer near the shielding layer; The material of the second transition layer is selected from one of silicon dioxide, lanthanum titanate, titanium oxide, and aluminum oxide; preferably, the thickness of the second transition layer is 5-15 nm.

[0015] Furthermore, the thickness of the lanthanum distitanate layer near the first transition layer is 51-60 nm; the thickness of the silicon dioxide layer is 42-51 nm; the thickness of the lanthanum distitanate layer away from the first transition layer is 91-95 nm; preferably, the total thickness of the color layer is 185-195 nm.

[0016] Furthermore, the masking layer is an ink layer; preferably, the thickness of the masking layer is 40-50 μm.

[0017] Furthermore, the material of the substrate is selected from polyethylene terephthalate (PET), polycarbonate (PC), glass fiber, metal, and acrylic sheet; the thickness of the substrate is 80-100μm.

[0018] Furthermore, when the material of the substrate is selected from polyethylene terephthalate, polycarbonate, and acrylic sheet, the textured layer is formed by a wire-drawing adhesive, and preferably the thickness of the textured layer is 8-12 μm; And / or, when the material of the substrate is selected from glass fiber or metal, the textured layer is formed by embossing, laser or chemical etching.

[0019] Furthermore, the substrate is provided with optically transparent adhesive (OCA adhesive), preferably with a thickness of 25±2µm.

[0020] The optical film described above in this invention can be prepared using magnetron sputtering or electron beam evaporation processes.

[0021] The present invention further provides an electronic device, the electronic device comprising the above-mentioned decorative film; Preferably, the electronic device is selected from at least one of a mobile terminal, a smart wearable device, and a camera module.

[0022] Compared with the prior art, the present invention has the following significant advantages: This invention effectively solves the technical problem of discoloration of existing optical films under prolonged sunlight exposure. The color layer in the optical film of this invention employs a sequentially stacked high-refractive-index layer (refractive index 2.1-2.5) and low-refractive-index layer (refractive index 1.45-1.55). This achieves a more uniform and stable color rendering effect through optical interference, improving the optical stability of the color layer and avoiding problems such as fading and color shift during long-term use, thus ensuring the color rendering effect of the optical film. Furthermore, by controlling the band gap width range of the high-refractive-index layer material (≥3.5eV), it can absorb ultraviolet light and convert it into heat energy. Simultaneously, the high-refractive-index layer has a certain scattering effect on ultraviolet light. The combination of absorption and scattering effectively blocks ultraviolet light penetration, eliminates the photocatalytic defects of titanium dioxide, and significantly improves the film's resistance to ultraviolet aging. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0024] Figure 1 This is a schematic diagram of the structure of the optical film of the present invention; 31-First transition layer; 321-Lanium disitinatate layer; 322-Silicon dioxide layer; 323-Lanium disitinatate layer; 33-Second transition layer.

[0025] Figure 2 This is a schematic diagram of the structure of the decorative film of the present invention; 1-Substrate; 2-Texture layer; 31-First transition layer; 32-Color layer; 33-Second transition layer; 4-Mask layer; Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] The terms "preferred," "further preferred," and "more preferred" used in this invention, followed by technical features, constitute preferred embodiments of the invention in a specific aspect, but should not be construed as limiting the scope of protection. When the preferred definitions at each level are combined in a progressive relationship, the degree of preference increases progressively.

[0028] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0029] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0030] In a specific embodiment of the present invention, an optical film is first provided, including a color layer, wherein the color layer includes a high refractive index layer and a low refractive index layer stacked sequentially. The high refractive index layer has a refractive index of 2.1-2.5 and a band gap width of ≥3.5eV; the low refractive index layer has a refractive index of 1.45-1.55.

[0031] The optical film of this invention combines the refractive indices of the high-refractive-index layer and the low-refractive-index layer, achieving a more uniform and stable color rendering effect through optical interference, improving the optical stability of the color layer, avoiding fading and color deviation during long-term use, ensuring the color rendering effect of the optical film, and controlling the band gap width range of the high-refractive-index layer material (≥3.5eV), i.e., having a wide ultraviolet absorption range, capable of absorbing ultraviolet light and converting it into heat energy. At the same time, the high-refractive-index layer has a certain scattering effect on ultraviolet light. The combination of absorption and scattering can effectively block ultraviolet light penetration, significantly improving the film's resistance to ultraviolet aging.

[0032] In addition to effectively absorbing ultraviolet light and converting it into heat energy, the optical film of this invention, due to the sequential stacking of a high refractive index layer (refractive index 2.1-2.5, band gap width ≥3.5eV) and a low refractive index layer (refractive index 1.45-1.55), requires high-energy photons to excite valence band electrons to conduction band transitions, which can reduce the probability of photogenerated carriers (photogenerated electrons and holes) being generated under ultraviolet irradiation.

[0033] Meanwhile, the high-refractive-index layer of this invention exhibits weak interfacial diffusion between the high-refractive-index layer and the low-refractive-index layer, and good thermal expansion coefficient stress compatibility, which reduces interlayer cracking and delamination problems under humid heat and ultraviolet cycling environments, and enhances the stability of interlayer bonding; moreover, the film has excellent resistance to crystallization and water vapor barrier capabilities, effectively improving the overall structural stability and service life of the optical film.

[0034] Furthermore, the material of the high refractive index layer is independently selected from any one of lanthanide metal oxyacid salts and rare high-melting-point binary metal oxides; the material of each low refractive index layer is independently selected from any one of inorganic fluorides and inorganic oxides.

[0035] The high refractive index layer of this invention employs lanthanide metal oxyacid salts (band gap width 3.5-6.0 eV) and rare high-melting-point binary metal oxides (band gap width 5.3-6.0 eV). Compared to titanium dioxide, these materials have a wider optical band gap, effectively absorbing ultraviolet light and converting it into heat energy. The high refractive index of these materials also provides some scattering effect on ultraviolet light. The combination of scattering and absorption more effectively blocks the penetration of ultraviolet light. Therefore, it significantly improves the film system's resistance to ultraviolet aging.

[0036] Specifically, lanthanide metal oxoacids possess stable high refractive indices and low dispersion characteristics. When applied to the color layer of optical films, they allow for precise control of the film's optical thickness, achieving accurate color rendering through optical interference effects, resulting in uniform color and minimal color deviation. The materials exhibit low intrinsic absorption in the visible light range, minimizing optical loss and ensuring excellent light transmittance of the optical film. Simultaneously, their stable crystal structure provides excellent heat resistance, humidity resistance, and UV aging resistance, inhibiting fading, yellowing, and haze increase in the color layer during long-term use, achieving a synergistic effect of coloring and UV protection. Rare high-melting-point binary metal oxides possess high melting points, low vapor pressures, and excellent chemical stability, along with stable refractive indices. Their application to the color layer of optical films allows for the control of thin-film optical interference conditions to achieve effective color rendering, while simultaneously improving the color layer's resistance to humidity and weathering.

[0037] Furthermore, the lanthanide metal oxyacid salt is selected from any one of lanthanum disitinitate (La2Ti2O7), lanthanum niobate (LaNbO4), and lanthanum yttrium oxide (LaYO3); the rare high-melting-point binary metal oxide is selected from hafnium oxide (HfO2) or scandium oxide (Sc2O3); the inorganic oxide is silicon dioxide, and the inorganic fluoride is magnesium fluoride.

[0038] The high refractive index layer material of this invention adopts any one of lanthanum disitintanate (La₂Ti₂O₇), lanthanum niobate (LaNbO₄), lanthanum yttrium oxide (LaYO₃), hafnium oxide (HfO₂), and scandium oxide (Sc₂O₃). The main advantage is that these materials possess more stable crystal structures; for example, scandium oxide has a manganese-iron-feldspar structure, hafnium oxide has a fluorite structure, and lanthanum disitintanate, lanthanum niobate, and lanthanum yttrium oxide have a perovskite structure. The materials themselves are chemically inert, resistant to acids and alkalis, and resistant to high temperatures, and will not decompose or discolor under long-term ultraviolet irradiation. This further enhances the film system's resistance to ultraviolet aging.

[0039] In one specific embodiment of the present invention, the material of the high refractive index layer is selected from lanthanum disitinocate, and the material of the low refractive index layer is selected from silicon dioxide.

[0040] Lanthanum disitinate crystals consist of alternating layers of perovskite composed of TiO6 octahedra and insulating La2O2 fluorite-type layers, forming a quasi-two-dimensional crystal structure. The TiO6 octahedral framework possesses a high atomic shift threshold energy. 4+ The low cation mobility, combined with the synergistic effect of the two, inhibits the formation and long-range propagation of radiation-induced defects. Simultaneously, the material's low thermal conductivity allows the localized thermal peaks formed by radiation energy deposition to trigger transient annealing within tens of picoseconds, prompting displaced atoms to return to their lattice sites and achieving transient in-situ self-repair of irradiation damage. Furthermore, the perovskite sheets can accommodate high concentrations of point defects through synergistic lattice distortion modes such as TiO6 octahedral tilt, effectively releasing irradiation-induced localized stress. At the optical level, lanthanum titanate has a band gap of approximately 3.8 eV, exhibiting a wider ultraviolet absorption range than anatase titanium dioxide (3.2 eV) and rutile titanium dioxide (3.0 eV). The larger band gap requires higher-energy photons to excite valence band electrons to conduction band transitions, reducing the probability of photogenerated carriers (photogenerated electrons and holes) generation under ultraviolet irradiation. Simultaneously, due to the layered structure of lanthanum titanate, the movement of photogenerated electrons and holes is confined within the two-dimensional perovskite sheets, allowing them to move only in the plane. This increases the recombination probability of photogenerated electrons and holes, resulting in photocatalytic inertness and reducing lattice photocorrosion damage induced by ultraviolet light (such as oxygen vacancy formation, Ti...). 4+ (Reduction, etc.). Lanthanum disitinate can effectively solve the UV aging problem faced by optical films during long-term use.

[0041] The silicon dioxide and lanthanum distitanate used in this invention have refractive indices of approximately 1.46 and 2.30 in the 550nm band, respectively. The alternating high and low refractive index film system can selectively enhance the transmission or reflection of a certain band in the visible light band through light interference, thereby obtaining the desired color.

[0042] Furthermore, the total thickness of the color layer is 50-300 nm, and the thickness of the low refractive index layer and the high refractive index layer are each independently 10-130 nm.

[0043] The color layer of an optical film is based on the interference principle of optical thin films. By adjusting the film material, thickness and structure, the transmission or reflection of a certain band in the visible light band is selectively increased, while the transmission or reflection of other bands is reduced, so that the colors corresponding to the bands with higher transmission or reflectivity are displayed.

[0044] This invention combines lanthanum distitanate with high refractive index and silicon dioxide with low refractive index at different film thicknesses. By using the interference principle of optical thin films, different dazzling color effects can be obtained. For example, if the thickness of the first lanthanum distitanate film is increased, the optical film color will turn yellow; if the thickness of the second silicon dioxide film is increased, the optical film color will turn reddish-yellow. The film thickness combination in the above embodiment can obtain the target yellow-green color effect.

[0045] The present invention also provides a decorative film comprising a shielding layer, the aforementioned optical film, a textured layer, and a substrate stacked sequentially.

[0046] The decorative film using the optical film of this invention has excellent anti-ultraviolet aging properties, and can also obtain decorative films with different dazzling color effects.

[0047] Furthermore, the optical film also includes a first transition layer; the first transition layer is disposed on the side of the color layer near the texture layer, and the material of the first transition layer is a mixture of silicon dioxide and aluminum oxide; Preferably, the thickness of the first transition layer is 5-15 nm.

[0048] In one specific embodiment of the present invention, the optical film is yellow-green, and the color layer consists of three layers, which are, sequentially from the side closest to the first transition layer, a lanthanum distitanate layer, a silicon dioxide layer, and a lanthanum distitanate layer; the thickness of the lanthanum distitanate layer near the first transition layer is 51-60 nm; the thickness of the silicon dioxide layer is 42-51 nm; and the thickness of the lanthanum distitanate layer away from the first transition layer is 91-95 nm; preferably, the total thickness of the color layer is 185-195 nm.

[0049] The first transition layer, acting as an intermediate transition layer, enables strong interfacial bonding between the color layer and the texture layer, and also enhances the bonding force between the first transition layer and the color layer, reducing film cracking. The mixture of aluminum oxide and silicon dioxide can effectively buffer internal stress; it exhibits good miscibility at high temperatures, forming a stable aluminosilicate glass phase that is not prone to phase separation or crystallization; it can be matched with high refractive index layers to obtain the designed dazzling color effect.

[0050] For example, lanthanum disitinocate (La₂Ti₂O₇) contains the rare earth element lanthanum (La). La ions are positively charged and readily form strong coordination bonds with oxygen (O) on the surface of the silicon-aluminum mixed layer, forming a continuous and dense "metal-oxygen" network through shared oxygen atoms. Meanwhile, Al and Si atoms in the aluminum oxide and silicon dioxide mixture readily form stable Al-O and Si-O bonds with oxygen in lanthanum disitinocate, thereby enhancing the film adhesion. During the evaporation coating process, Si and Al atoms undergo short-range diffusion to the lanthanum titanate surface, forming a gradient interface layer. Al atoms may occupy La or Ti sites in the lanthanum titanate lattice to form a solid solution, increasing the mechanical interlocking strength and further enhancing the interfacial adhesion.

[0051] The first transition layer of this invention uses a silicon-aluminum oxide mixture to enhance the adhesion between the first transition layer and the texture layer; it can also be bonded to the color layer through covalent bonds, further enhancing the adhesion between the first transition layer and the color layer.

[0052] Furthermore, the mass ratio of silicon dioxide to aluminum oxide is (1-3):(17-19).

[0053] The present invention uses the above-mentioned mass ratio range of silicon dioxide and aluminum oxide to make the gradient modulus between the soft substrate and the hard functional layer, effectively buffering internal stress; it has better miscibility at high temperature, can form a stable aluminosilicate glass phase, and is not prone to phase separation or crystallization; and it makes the refractive index between 1.46 and 1.76, which matches the high refractive index layer, thereby controlling the interface reflection to obtain the designed dazzling color effect.

[0054] Furthermore, the optical film also includes a second transition layer, which is disposed on the side of the color layer near the shielding layer; The material of the second transition layer is selected from one of silicon dioxide, lanthanum titanate, titanium dioxide, and aluminum oxide; Preferably, the thickness of the second transition layer is 5-15 nm.

[0055] The second transition layer material used in this invention can be used in optical films with different color requirements and has good adhesion to the masking layer (ink layer).

[0056] Furthermore, the masking layer may be selected from the ink layer, and preferably the thickness of the masking layer is 40-50 μm.

[0057] Specifically, the ink layer can be obtained by spraying, spin coating, screen printing, etc., and the present invention does not impose any special limitations.

[0058] The ink layer has strong opacity, which can effectively block unwanted light from passing through, meeting the product's requirements for light-blocking and color rendering.

[0059] Furthermore, the material of the substrate is selected from polyethylene terephthalate (PET), polycarbonate (PC), glass fiber, metal, and acrylic sheet; the thickness of the substrate is 80-100μm.

[0060] The substrate used in this invention has good flatness and mechanical stability, which can provide a stable adhesion base for subsequent functional layers.

[0061] Furthermore, when the material of the substrate is selected from polyethylene terephthalate, polycarbonate, and acrylic sheet, the textured layer is formed by a wire-drawing adhesive, and preferably the thickness of the textured layer is 8-12 μm; And / or, when the material of the substrate is selected from glass fiber or metal, the textured layer is formed by embossing, laser or chemical etching.

[0062] After curing, the wire-drawing adhesive stably retains the pre-pressed texture structure, exhibits strong adhesion to the substrate, has low cost, and is easy to process, making it suitable for mass production. For high-hardness substrates such as fiberglass and metal, texture layers can be formed through embossing, laser etching, chemical etching, etc., resulting in high texture forming precision and strong texture stability. No additional adhesive materials are required, avoiding the adverse effects of adhesive curing shrinkage on texture precision, making it suitable for processing products with high requirements for texture complexity and precision.

[0063] Furthermore, the substrate is provided with optically transparent adhesive (OCA adhesive), preferably with a thickness of 25±2µm.

[0064] The substrate of this invention is also provided with optically transparent adhesive, which can bond and fix the optical film to the product to be used without affecting the optical display effect of the optical film itself, ensuring the clarity and aesthetics of the finished product, and after bonding, it is not easy to have problems such as edge lifting, bulging, or delamination, thus improving the stability and service life of the overall structure.

[0065] The present invention also provides that the above-mentioned optical film can be prepared by magnetron sputtering or electron beam evaporation, or other evaporation coating methods, and no specific requirements are specified.

[0066] For example, the preparation method can be adopted, including the following steps: The substrate is fixed on the umbrella of the vacuum evaporation coating machine, and the material is deposited layer by layer using electron beam evaporation technology. By controlling the deposition rate of lanthanum titanate and silicon dioxide, the film thickness reaches the predetermined requirement.

[0067] The present invention further provides an electronic device, the electronic device comprising the above-mentioned decorative film; Preferably, the electronic device is selected from at least one of a mobile terminal, a smart wearable device, and a camera module; More preferably, the mobile terminal is a mobile phone, and the smart wearable device is a smartwatch.

[0068] The optical film of this invention can maintain good optical transmittance while ensuring the decorative effect of the appearance. It will not obstruct or interfere with the display and shooting functions of the electronic device itself. It also has strong structural stability and will not cause discoloration, texture deformation, delamination or edge lifting problems after long-term use. It can adapt to the design requirements of various thin and light electronic devices.

[0069] The technical solution of the present invention will be described in detail below through embodiments and comparative examples. It should be noted that the following embodiments are only used to help understand the technical solution of the present invention and do not constitute any limitation on the scope of protection of the present invention.

[0070] Unless otherwise specified, specific techniques or conditions in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. All raw materials used in this invention are readily available in the domestic market.

[0071] Example 1 like Figure 1 As shown, this embodiment provides a yellow-green optical film and its preparation method. The optical film consists of a second transition layer, a color layer, and a first transition layer stacked sequentially. The second transition layer is a silicon dioxide layer with a thickness of 10 nm. The color layer has a three-layer structure, consisting of a first lanthanum disitinate layer, a second silicon dioxide layer, and a third lanthanum disitinate layer, sequentially arranged from the side closest to the first transition layer. The first lanthanum disitinate layer has a thickness of 51 nm; the second silicon dioxide layer has a thickness of 47 nm; and the third lanthanum disitinate layer has a thickness of 95 nm. The first transition layer is a silicon-aluminum hybrid layer, composed of 95 wt.% silicon dioxide and 5 wt.% aluminum oxide; the thickness of the first transition layer is 10 nm.

[0072] The yellow-green optical film provided in this embodiment is prepared using evaporation coating technology. The specific preparation steps are as follows: The PET substrate is fixed on the umbrella of the vacuum evaporation coating machine by magnets, and then layer-by-layer deposition is performed by electron beam evaporation. The deposition rates of the first transition layer, lanthanum dititanate, silicon dioxide and the second transition layer are 1.5 A / s, 4.0 A / s, 1.5 A / s and 4.0 A / s, respectively, until the film thickness reaches the preset value.

[0073] like Figure 2As shown, this embodiment also provides a decorative film having the yellow-green optical film, the decorative film comprising a masking layer, the yellow-green optical film, a textured layer, and a substrate stacked sequentially. The second transition layer is located near the masking layer, which is an ink layer with a thickness of 45±5 μm. The first transition layer is located near the textured layer, which is a brushed adhesive layer with a thickness of 10±2 μm; the substrate is a PET substrate layer with a thickness of 49±1 μm.

[0074] Example 2 This embodiment provides a yellow-green optical film and its preparation method. The only difference from Embodiment 1 is that the first transition layer is a silicon-aluminum hybrid layer, which is composed of 90 wt.% silicon dioxide and 10 wt.% aluminum oxide. The rest is the same as in Embodiment 1, and will not be repeated here.

[0075] The composition of the decorative film provided in this embodiment is the same as that in Embodiment 1, and will not be repeated here.

[0076] Example 3 This embodiment provides a yellow-green optical film and its preparation method. The only difference from Embodiment 2 is that the first transition layer is a silicon-aluminum hybrid layer, which is composed of 85 wt.% silicon dioxide and 15 wt.% aluminum oxide. The rest is the same as in Embodiment 1, and will not be repeated here.

[0077] The composition of the decorative film provided in this embodiment is the same as that in Embodiment 1, and will not be repeated here.

[0078] Example 4 This embodiment provides a yellow-green optical film and its preparation method. The only difference from Embodiment 2 is that the thickness of the first lanthanum disitinate layer is 15 nm; the thickness of the second silicon dioxide layer is 50 nm; and the thickness of the third lanthanum disitinate layer is 50 nm. Everything else is the same as in Embodiment 2 and will not be repeated here.

[0079] The composition of the decorative film provided in this embodiment is the same as that in Embodiment 1, and will not be repeated here.

[0080] Example 5 This embodiment provides a yellow-green optical film and its preparation method. The only difference from Embodiment 2 is that the thickness of the first lanthanum disitinate layer is 60 nm; the thickness of the second silicon dioxide layer is 20 nm; and the thickness of the third lanthanum disitinate layer is 120 nm. Everything else is the same as in Embodiment 2 and will not be repeated here.

[0081] The composition of the decorative film provided in this embodiment is the same as that in Embodiment 1, and will not be repeated here.

[0082] Example 6 This embodiment provides a yellow-green optical film and its preparation method. The only difference from Embodiment 2 is that the thickness of the first lanthanum disitinate layer is 60 nm; the thickness of the second silicon dioxide layer is 42 nm; and the thickness of the third lanthanum disitinate layer is 91 nm. Everything else is the same as in Embodiment 2 and will not be repeated here.

[0083] The composition of the decorative film provided in this embodiment is the same as that in Embodiment 1, and will not be repeated here.

[0084] Example 7 This embodiment provides an optical film and its preparation method. The only difference from Embodiment 2 is that the color layer is a three-layer film structure, consisting of a first lanthanum niobate layer, a second silicon dioxide layer, and a third lanthanum niobate layer, arranged sequentially from the bottom layer side. Everything else is the same as in Embodiment 2 and will not be repeated here.

[0085] The composition of the decorative film provided in this embodiment is the same as that in Embodiment 1, and will not be repeated here.

[0086] Example 8 This embodiment provides an optical film and its preparation method. The only difference from Embodiment 1 is that the color layer is a three-layer film structure, consisting of a first hafnium oxide layer, a second silicon dioxide layer, and a third hafnium oxide layer, sequentially from the bottom layer side. Everything else is the same as in Embodiment 2 and will not be repeated here.

[0087] The composition of the decorative film provided in this embodiment is the same as that in Embodiment 1, and will not be repeated here.

[0088] Comparative Example 1 This comparative example provides an optical film and its preparation method. The difference from Example 5 is that the color layer is a three-layer film structure, consisting of a first titanium dioxide layer, a second silicon dioxide layer, and a third titanium dioxide layer sequentially from the first transition layer side; the thickness of the first titanium dioxide layer is 23.3 nm; the thickness of the second silicon dioxide layer is 52 nm; and the thickness of the third titanium dioxide layer is 83.5 nm.

[0089] Comparative Example 2 This comparative example provides an optical film and its preparation method. The difference from Example 5 is that the color layer is a three-layer film structure, consisting of a first titanium dioxide layer, a second silicon dioxide layer, and a third titanium dioxide layer sequentially from the first transition layer side; the thickness of the first titanium dioxide layer is 55 nm; the thickness of the second silicon dioxide layer is 46 nm; and the thickness of the third titanium dioxide layer is 93 nm.

[0090] Comparative Example 3 This comparative example provides an optical film and its preparation method. The difference from Example 5 is that the color layer is a three-layer film structure, consisting of a first lanthanum distitanate layer, a second silicon dioxide layer, and a third titanium dioxide layer, sequentially from the first transition layer side. The rest is the same as in Example 5 and will not be repeated here.

[0091] The decorative films of the embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0092] Adhesion test (water boiling cross-cut test): The sample is boiled in water at 80℃±2℃ for 30 minutes and then removed and left to stand at room temperature for 2 hours. After confirming that there are no appearance defects such as wrinkles or peeling on the coating surface, a 2mm*2mm grid is cut out on the coating surface. Standard tape is used to vertically stick the grid area and then quickly peel off the tape. The actual area of ​​damage and peeling on the coating surface is calculated to determine the adhesion.

[0093] UV aging resistance test: This includes adhesion testing and color difference testing of samples after accelerated aging testing. The specific methods are as follows: (1) Cover half of the area to be tested on the test sample with tin foil, and place the test sample in the xenon lamp test chamber. Set the temperature of the test chamber to 40℃ dry heat and the irradiance of the lamp tube in the 340nm band to 0.55W / m. 2 The wavelength range is 300-800nm. The test is maintained for 20 hours, and then the solar radiation source is turned off for 4 hours. This is one cycle. Three cycles are performed to complete a 72-hour test. (2) Take out the sample and wait for it to return to room temperature. Check the appearance of the paint coating and use a colorimeter to test the color difference between the irradiated and aged areas and the areas covered by tin foil. (3) The appearance of the sample should be checked and the adhesion test should be performed at 4 hours, 24 hours, 48 ​​hours and 72 hours after the test. The adhesion test here is the cross-cut adhesion test, a standard adhesion test. A 2mm*2mm grid is cut out on the coating surface, and standard tape is used to vertically stick to the grid area and then quickly peel off the tape. The actual area of ​​damage and peeling off the coating surface is calculated to determine the adhesion.

[0094] Colorimetric (Lab value) testing standard: The CIE 1976 L*a*b* colorimetric system is adopted, using the CIE standard illuminant D65 as the light source. A reflectance spectrophotometer (such as a Konica Minolta CM-700d spectrophotometer) is used to measure the colorimetric parameters of the sample. The measurement geometry is d / 8° (diffuse illumination / 8° reception). Calibration is performed against both a standard white board and a black board. Measurements are taken at five different locations evenly selected on the sample surface, and the average value is taken as the L*, a*, and b* values ​​of the sample.

[0095] Table 1

[0096] As can be seen from the data in Table 1, the adhesion of the decorative film of the present invention after boiling is above 4B and there are no appearance defects such as wrinkling or peeling on the surface after boiling. The adhesion after UV aging test is also above 4B and the color difference ΔE < 2.8. No color change or coating peeling occurs due to ultraviolet irradiation.

[0097] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An optical film, characterized in that, Includes a color layer, which comprises a high refractive index layer and a low refractive index layer stacked sequentially; The high refractive index layer has a refractive index of 2.1-2.5 and a band gap width of ≥3.5eV; the low refractive index layer has a refractive index of 1.45-1.

55.

2. The optical film according to claim 1, characterized in that, The material of the high refractive index layer is independently selected from any one of lanthanide metal oxyacid salts and rare high-melting-point binary metal oxides.

3. The optical film according to claim 2, characterized in that, The lanthanide metal oxyacid salt is selected from any one of lanthanum disitinitate, lanthanum niobate, and lanthanum yttrium oxide; the rare high-melting-point binary metal oxide is selected from hafnium oxide or scandium oxide; The preferred material for the high refractive index layer is lanthanum disitinoate.

4. The optical film according to claim 1 or 2, characterized in that, The total thickness of the color layer is 50-300 nm, and the thickness of the low refractive index layer and the high refractive index layer are each 10-130 nm independently. Preferably, the optical film is yellow-green, and the color layer is a lanthanum distitanate layer, a silicon dioxide layer and a lanthanum distitanate layer stacked sequentially.

5. A decorative film, characterized in that, It includes a shielding layer, an optical film as described in any one of claims 1-4, a textured layer, and a substrate stacked sequentially.

6. The decorative film according to claim 5, characterized in that, The optical film further includes a first transition layer; the first transition layer is disposed on the side of the color layer near the texture layer, and the material of the first transition layer is a mixture of silicon dioxide and aluminum oxide; preferably, the mass ratio of aluminum oxide to silicon dioxide is (1-3):(17-19); more preferably, the thickness of the first transition layer is 5-15 nm.

7. The decorative film according to claim 5, characterized in that, The optical film further includes a second transition layer, which is disposed on the side of the color layer near the shielding layer; The material of the second transition layer is selected from one of silicon dioxide, lanthanum titanate, titanium dioxide, and aluminum oxide; Preferably, the thickness of the second transition layer is 5-15 nm.

8. The decorative film according to claim 6, characterized in that, The color layer is composed of a lanthanum distitanate layer, a silicon dioxide layer, and a lanthanum distitanate layer stacked sequentially. The thickness of the lanthanum distitanate layer near the first transition layer is 51-60 nm; the thickness of the silicon dioxide layer is 42-51 nm; and the thickness of the lanthanum distitanate layer away from the first transition layer is 91-95 nm. Preferably, the total thickness of the color layer is 185-195 nm.

9. The decorative film according to claim 5, characterized in that, The masking layer is an ink layer; preferably, the thickness of the masking layer is 40-50 μm; the material of the substrate is selected from polyethylene terephthalate, polycarbonate, acrylic sheet, glass fiber, and metal; preferably, the thickness of the substrate is 80-100 μm. And / or, the thickness of the texture layer is 8-12 μm; And / or, the substrate is provided with an optically transparent adhesive.

10. An electronic device, characterized in that, Includes the decorative film as described in any one of claims 5 to 9; Preferably, the electronic device is selected from at least one of a mobile terminal, a smart wearable device, and a camera module.

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