High-reflectivity optical film and backlight module

Abstract

The utility model relates to a high-reflectivity optical film and a backlight module. The high-reflectivity optical film comprises a biaxially oriented polypropylene layer and a silver layer which are stacked, inorganic filler particles are doped in the biaxially oriented polypropylene layer, the particle size of the inorganic filler particles is 20-400 nm, micropores are distributed in the biaxially oriented polypropylene layer, and the pore size of the micropores is 0.1-5 microns. The high reflectivity of biaxially oriented polypropylene is utilized, the inorganic filler particles are utilized to scatter light, the diffuse reflection effect is achieved through the micropores, large-angle incident light is converted into reflected light towards the light guide plate, and the light utilization rate is increased. The reflection effect of the silver layer is better than that of the biaxially oriented polypropylene layer, but the absorption rate of the silver layer to incident light is 2%-5%, the absorption of the biaxially oriented polypropylene layer is close to zero, and the biaxially oriented polypropylene layer is combined with the silver layer, so that the biaxially oriented polypropylene layer reflects most of light rays and reduces light absorption at the same time, and the reflection effect of the biaxially oriented polypropylene layer is improved. And the silver layer further efficiently reflects the escape light.

Description

Technical Field

[0001] The utility model relates to the technical field of optical elements, in particular to a high-reflectivity optical film and a backlight module. Background Art

[0002] Reflective film is an important optical component in the backlight module. It can reflect the light leaking from the bottom of the light guide plate back, reducing light loss and increasing the brightness of the backlight module. It is widely used in LCD TVs, laptops, and mobile phones.

[0003] Silver has high reflectivity in the visible and infrared bands. Reflective films based on the principle of specular reflection from a silver layer possess excellent optical properties. However, the silver layer absorbs incident light to a certain extent, with an absorption rate of 2% to 5%. This limits the utilization of light, and the reflectivity of reflective films needs to be further improved. Utility Model Content

[0004] Based on this, it is necessary to provide a high-reflectivity optical film and a backlight module to improve the reflectivity.

[0005] A high-reflectivity optical film comprises a stacked biaxially oriented polypropylene layer and a silver layer, wherein the biaxially oriented polypropylene layer is doped with inorganic filler particles, the particle size of the inorganic filler particles is 20 nm to 400 nm, and micropores are distributed in the biaxially oriented polypropylene layer, the pore size of the micropores is 0.1 μm to 5 μm.

[0006] In one embodiment, the inorganic filler particles include a TiO2 core and a SiO2 coating layer coating the TiO2 core.

[0007] In one embodiment, the volume fraction of the inorganic filler particles in the biaxially oriented polypropylene layer is 10% to 30%.

[0008] In one embodiment, the porosity of the biaxially oriented polypropylene layer is 10% to 40%.

[0009] In one embodiment, the biaxially oriented polypropylene layer includes a plurality of stacked sub-layers, and the pore sizes of the micropores in different sub-layers increase successively as they approach the silver layer.

[0010] In one embodiment, the biaxially oriented polypropylene layer includes a first sublayer, a second sublayer, and a third sublayer stacked in sequence, the first sublayer is located on the side of the second sublayer away from the silver layer, the third sublayer is located on the side of the second sublayer close to the silver layer, the pore size of the micropores in the first sublayer is 0.1 μm~0.5 μm, the pore size of the micropores in the second sublayer is 0.8 μm~1.5 μm, and the pore size of the micropores in the third sublayer is 3 μm~5 μm.

[0011] In one embodiment, the thickness of the biaxially oriented polypropylene layer is 10 μm to 100 μm.

[0012] In one embodiment, the thickness of the silver layer is 20 nm to 100 nm.

[0013] In one embodiment, the high reflectivity optical film further includes a first topography layer, which is disposed on a side of the biaxially oriented polypropylene layer away from the silver layer, and has a moth-eye structure.

[0014] In one embodiment, the high reflectivity optical film further includes a second topography layer, which is disposed on a side of the biaxially oriented polypropylene layer facing the silver layer, and has a moth-eye structure.

[0015] In one embodiment, the high reflectivity optical film further comprises a primer layer, wherein the primer layer is disposed between the second topography layer and the silver layer, and the primer layer comprises at least one of a polyurethane layer, an acrylic layer, and a cycloolefin copolymer layer.

[0016] In one embodiment, the high reflectivity optical film further includes a supporting substrate layer and an adhesive layer, wherein the supporting substrate layer is disposed between the primer layer and the second topography layer, and the adhesive layer is disposed between the supporting substrate layer and the second topography layer.

[0017] A backlight module comprises a light source, a brightness enhancement component, a diffusion film, a light guide plate and the high-reflectivity optical film described in any one of the above embodiments, wherein the diffusion film and the high-reflectivity optical film are respectively arranged on opposite sides of the light guide plate, the brightness enhancement component is arranged on the side of the diffusion film away from the light guide plate, and the light source is arranged on the side of the light guide plate.

[0018] Compared with traditional solutions, the above-mentioned high-reflectivity optical film and backlight module have the following beneficial effects:

[0019] The above-mentioned high-reflectivity optical film can be used in backlight modules. A biaxially oriented polypropylene layer containing inorganic filler particles of a specific particle size and micropores of a specific pore size is placed on the silver layer. The high reflectivity of the biaxially oriented polypropylene is utilized, and the inorganic filler particles in the biaxially oriented polypropylene layer scatter light. The micropores achieve diffuse reflection, converting large-angle incident light into reflected light toward the light guide plate, thereby improving light utilization. The silver layer has a better reflective effect than the biaxially oriented polypropylene layer, but the silver layer has an absorption rate of 2% to 5% for incident light, while the biaxially oriented polypropylene layer absorbs incident light close to zero. By combining the biaxially oriented polypropylene layer with the silver layer, the biaxially oriented polypropylene layer serves as the main reflective surface, reflecting most of the light while reducing its absorption of incident light. The silver layer further efficiently reflects escaping light, thereby increasing the reflectivity of the high-reflectivity optical film to over 98%, achieving full utilization of light from side light sources.

[0020] The above-mentioned backlight module includes the high-reflectivity optical film described in any of the above-mentioned embodiments, and thus has corresponding technical features and can obtain corresponding beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of a high reflectivity optical film according to an embodiment;

[0022] Figure 2 To include Figure 1 Schematic diagram of the structure of the backlight module of the high reflectivity optical film shown.

[0023] Description of reference numerals:

[0024] 100. High-reflectivity optical film; 110. Biaxially oriented polypropylene layer; 111. First sublayer; 112. Second sublayer; 113. Third sublayer; 120. Silver layer; 130. First morphology layer; 140. Second morphology layer; 150. Primer layer; 160. Support substrate layer; 170. Adhesive layer; 180. Water and oxygen barrier layer; 190. AF layer; 200. Backlight module; 201. Light source; 202. Diffuser film; 203. Light guide plate; 204. Brightness enhancement component; 2041. Upper brightness enhancement film; 2042. Lower brightness enhancement film. DETAILED DESCRIPTION

[0025] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of this invention are for the purpose of describing specific embodiments only and are not intended to limit this invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0029] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0030] like Figure 1 As shown, a high-reflectivity optical film 100 according to one embodiment of the present invention includes a stacked biaxially oriented polypropylene layer 110 and a silver layer 120. The biaxially oriented polypropylene layer 110 is doped with inorganic filler particles. The inorganic filler particles have a particle size of 20 nm to 400 nm. Micropores are distributed within the biaxially oriented polypropylene layer 110. The pore size of the micropores ranges from 0.1 μm to 5 μm. Biaxially oriented polypropylene is BOPP.

[0031] The high-reflectivity optical film 100 can be used in backlight modules. A biaxially oriented polypropylene layer 110 containing inorganic filler particles of a specific size and micropores of a specific pore size is disposed on a silver layer 120. Leveraging the high reflectivity of biaxially oriented polypropylene, the inorganic filler particles in the biaxially oriented polypropylene layer 110 scatter light, and the micropores achieve diffuse reflection, the film converts wide-angle incident light into reflected light directed toward the light guide plate, thereby improving light utilization. The silver layer 120 has a better reflectivity than the biaxially oriented polypropylene layer 110, but the silver layer 120 has an absorption rate of 2% to 5% for incident light, while the biaxially oriented polypropylene layer 110 absorbs almost zero light. By combining the biaxially oriented polypropylene layer 110 with the silver layer 120, the biaxially oriented polypropylene layer 110 serves as the primary reflective surface, reflecting most light while minimizing absorption of incident light. The silver layer 120 further efficiently reflects escaping light, thereby increasing the reflectivity of the high-reflectivity optical film 100 to over 98%, fully utilizing light from side sources.

[0032] In some examples, the inorganic filler particles include a TiO2 core and a SiO2 coating layer covering the TiO2 core. The inorganic filler particles have a good light scattering effect.

[0033] The particle size of the inorganic filler particles is 20 nm to 400 nm, for example, 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, etc., or a range between any two of the above values.

[0034] In some examples, the volume fraction of the inorganic filler particles in the biaxially oriented polypropylene layer 110 (including the micropores) is 10% to 30%, specifically, for example, 10%, 15%, 20%, 25%, 30%, etc.

[0035] In some examples, the biaxially oriented polypropylene layer 110 has a thickness of 10 μm to 100 μm, specifically 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, etc.

[0036] The micropores in the biaxially oriented polypropylene layer 110 can be formed by adding a foaming agent during the film preparation process. The foaming agent may be, for example, but not limited to, azodicarbonamide, biurea, etc. The pore size of the micropores can be controlled by selecting the type of foaming agent and the foaming conditions.

[0037] The pore diameter of the micropores in the biaxially oriented polypropylene layer 110 is 0.1 μm to 5 μm, and specifically, for example, 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0038] In some examples, the porosity of the biaxially oriented polypropylene layer 110 is 10% to 40%, specifically, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc.

[0039] In some examples, the biaxially oriented polypropylene layer 110 includes multiple sublayers stacked together. The pore sizes of the micropores in the different sublayers increase as they approach the silver layer 120. By providing multiple sublayers with different pore sizes, the reflection effect of light of different wavelengths can be improved.

[0040] The biaxially oriented polypropylene layer 110 can be formed by heat-compression bonding a plurality of membrane layers with different pore sizes.

[0041] like Figure 1 As shown, in some examples, the biaxially oriented polypropylene layer 110 includes a first sublayer 111, a second sublayer 112, and a third sublayer 113, which are stacked in sequence. The first sublayer 111 is located on the side of the second sublayer 112 away from the silver layer 120. The third sublayer 113 is located on the side of the second sublayer 112 close to the silver layer 120. The pore size of the micropores in the first sublayer 111 is 0.1 μm to 0.5 μm, which can improve the reflection effect of blue light. The pore size of the micropores in the second sublayer 112 is 0.8 μm to 1.5 μm, which can improve the reflection effect of green light. The pore size of the micropores in the third sublayer 113 is 3 μm to 5 μm, which can improve the reflection effect of red light.

[0042] The silver layer 120 can be prepared by a magnetron sputtering process, for example, the process is as follows: first, the cavity is evacuated to 2×10 -5 Pa~8×10 -5 Pa, Ar is introduced at 20 sccm~100 sccm, direct current (DC) mode is adopted, the working gas pressure is 0.1Pa~1Pa, and the power is 10W~40W.

[0043] In some examples, the thickness of the silver layer 120 is 20 nm to 100 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.

[0044] In some examples, the high-reflectivity optical film 100 further includes a first topographic layer 130. The first topographic layer 130 is disposed on a side of the biaxially oriented polypropylene layer 110 away from the silver layer 120. The first topographic layer 130 has a moth-eye structure. The first topographic layer 130 can convert incident light at a large angle into uniform light perpendicular or nearly perpendicular to the light guide plate, thereby improving the brightness of the backlight module.

[0045] In some examples, the first topography layer 130 is a UV adhesive layer. The first topography layer 130 is prepared by first coating UV adhesive on the biaxially oriented polypropylene layer 110, forming a surface pattern by embossing with precision equipment, and then curing it with ultraviolet light.

[0046] In some examples, the high-reflectivity optical film 100 further includes a second topographical layer 140. The second topographical layer 140 is disposed on the side of the biaxially oriented polypropylene layer 110 facing the silver layer 120. The second topographical layer 140 has a moth-eye structure. The second topographical layer 140 can convert incident light at a large angle into uniform light perpendicular or nearly perpendicular to the light guide plate, thereby improving the brightness of the backlight module.

[0047] In some examples, the second topography layer 140 is a UV adhesive layer. The second topography layer 140 is prepared by first coating UV adhesive on the biaxially oriented polypropylene layer 110, forming a surface pattern by embossing with precision equipment, and then curing it with ultraviolet light.

[0048] In some examples, the high-reflectivity optical film 100 further includes a primer layer 150. Primer layer 150 is disposed between the second topographical layer 140 and the silver layer 120. Primer layer 150 includes at least one of a polyurethane layer, an acrylic layer, and a cyclic olefin copolymer layer. Thus, primer layer 150 can improve interlayer connectivity while also providing a barrier against moisture and oxygen.

[0049] In some examples, the thickness of the primer layer 150 is 0.5µm to 2µm, for example, 0.5µm, 0.8µm, 1µm, 1.3µm, 1.5µm, 1.8µm, 2µm, etc.

[0050] In some examples, the high reflectivity optical film 100 further includes a supporting substrate layer 160 and an adhesive layer 170. The supporting substrate layer 160 is disposed between the primer layer 150 and the second topography layer 140. The adhesive layer 170 is disposed between the supporting substrate layer 160 and the second topography layer 140.

[0051] In some examples, the transparent substrate layer is a polymer layer. Furthermore, the transparent substrate layer is a PET layer. In some examples, the thickness of the transparent substrate layer is 20µm to 100µm, specifically 20µm, 40µm, 60µm, 80µm, 100µm, etc. In some examples, the light transmittance of the transparent substrate layer is 88% to 91%, specifically 88%, 88.5%, 89%, 89.5%, 90%, 90.5%, 91%, etc.

[0052] Adhesive layer 170 comprises, for example, acrylic resin. Adhesive layer 170 may be further doped with hollow silica microspheres, for example, with a particle size of 0.5 μm to 2 μm. This results in a refractive index of 1.35 to 1.45 for adhesive layer 170, which matches the refractive index of biaxially oriented polypropylene layer 110 (refractive index of approximately 1.49) and silver layer 120 (refractive index of approximately 1.33), thereby reducing interfacial reflection loss and improving reflectivity.

[0053] In some examples, the thickness of the adhesive layer 170 is 3 μm to 8 μm, specifically 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc.

[0054] In some examples, the high reflectivity optical film 100 further includes a water and oxygen barrier layer 180. The water and oxygen barrier layer 180 is disposed on the side of the silver layer 120 away from the biaxially oriented polypropylene layer 110. The water and oxygen barrier layer 180 includes at least one of an inorganic oxide layer, an inorganic nitride layer, and an organic polymer layer.

[0055] The material of the inorganic oxide layer may be, but is not limited to, at least one of Al2O3, SiO2, TiO2, and Ta2O5. The material of the inorganic nitride layer may be, but is not limited to, at least one of AlN and Si3N4. The material of the organic polymer layer may be, but is not limited to, at least one of polyurethane, acrylic, and cycloolefin copolymer.

[0056] When the water and oxygen barrier layer 180 is an inorganic oxide layer or an inorganic nitride layer, the thickness is, for example, 10 nm to 50 nm, specifically 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc. The inorganic oxide layer and the inorganic nitride layer can be prepared by a magnetron sputtering process, for example, the process is as follows: first, the chamber is evacuated to 2×10 -5 Pa~8×10 -5 Pa, Ar is introduced at 20 sccm~100 sccm, RF mode is adopted, the working gas pressure is 0.1Pa~1Pa, and the power is 20W~55W.

[0057] When the water and oxygen barrier layer 180 is an organic polymer layer, the thickness thereof is, for example, 0.5 μm to 2 μm, specifically, 0.5 μm, 1 μm, 1.5 μm, 2 μm, etc. The organic polymer layer can be formed by coating a polymer and curing it.

[0058] In some examples, the high-reflectivity optical film 100 further includes an AF layer 190. The AF layer 190 is disposed on the side of the water and oxygen barrier layer 180 away from the silver layer 120. The AF layer 190 has low surface energy and high hardness, providing anti-fingerprint and scratch resistance, thereby preventing the high-reflectivity optical film 100 from being damaged during manufacturing, transportation, and assembly, which could reduce the reflective performance of the product.

[0059] AF layer 190 is formed by applying an AF coating solution and drying it. The AF coating solution contains 40% to 65% by mass of an acrylic resin prepolymer, 10% to 15% by mass of an acrylate monomer, 1% to 5% by mass of an initiator, 0.5% to 1.5% by mass of a fluorinated additive, and 23% to 48% by mass of a solvent. Examples of the acrylic resin prepolymer include trifunctional urethane acrylic resin prepolymers and hexafunctional urethane acrylic resin prepolymers. Examples of the acrylate monomer include trifunctional acrylate monomers. Examples of the initiator include Irgacure 184. Examples of the fluorinated additive include fluorocarbon cyclic ethers, fluoroalkanes, fluorosilicones, and perfluoropolyethers. Examples of the solvent include ethyl acetate.

[0060] Further, if Figure 2 As shown, the present invention further provides a backlight module 200, comprising a light source 201, a diffusion film 202, a light guide plate 203, and any of the above-described high-reflectivity optical films 100. The diffusion film 202 and the high-reflectivity optical film 100 are disposed on opposite sides of the light guide plate 203, and the light source 201 is disposed on the side of the light guide plate 203.

[0061] The light source 201 is, for example, an LED.

[0062] The diffusion film 202 can improve the brightness uniformity of the entire backlight surface by scattering light, making the light more uniform and soft, and reducing the brightness and darkness differences caused by problems such as uneven light output from the light guide plate 203 or the light emitting angle of the light source 201.

[0063] In some examples, the backlight module 200 further includes a brightness enhancement component 204, which is disposed on a side of the diffusion film 202 away from the light guide plate 203. The surface of the brightness enhancement component 204 has many tiny prism structures that can focus and direct light forward, thereby increasing the vertical brightness of the backlight module 200, thereby enhancing the display effect, reducing light scattering in the horizontal direction, and improving light utilization efficiency.

[0064] In some examples, the brightness enhancement component 204 includes an upper brightness enhancement film 2041 and a lower brightness enhancement film 2042. The lower brightness enhancement film 2042 is located between the upper brightness enhancement film 2041 and the diffuser film 202. The lower brightness enhancement film 2042 initially converges and redirects light passing through the diffuser film 202. The upper brightness enhancement film 2041 further performs secondary focusing and optimizes light uniformity, thereby achieving progressive light convergence and ultimately achieving a balance between brightness, power, and uniformity.

[0065] The following specific embodiments are provided to further illustrate the present invention. The present invention provides the following specific embodiments for a better understanding of the present invention, but is not limited to the specific embodiments and does not limit the scope of protection of the present invention.

[0066] Example 1

[0067] The reflective film provided in this embodiment includes a first morphology layer, a biaxially oriented polypropylene layer, a second morphology layer, an adhesive layer, a supporting substrate layer, a primer layer, a silver layer, a water and oxygen barrier layer, and an AF layer stacked in sequence.

[0068] The first and second topography layers are both 0.5µm thick UV adhesive layers, onto which the moth-eye structure is formed using an embossing process. The biaxially oriented polypropylene layer is doped with inorganic filler particles, consisting of a TiO2 core encapsulated by a SiO2 coating. The particle size distribution ranges from 100nm to 400nm. The volume fraction of the inorganic filler particles is 17%. Micropores are distributed within the biaxially oriented polypropylene layer. The pore size distribution ranges from 0.1µm to 5µm, resulting in a porosity of 22%. The biaxially oriented polypropylene layer is 60µm thick. The adhesive layer is made of acrylic resin and is 4µm thick. The supporting substrate layer is made of PET and is 25µm thick. The primer layer is made of acrylic and is 1µm thick. The silver layer is 80nm thick. The water and oxygen barrier layer is made of aluminum oxide and is 30nm thick. The AF layer is formed by applying an AF coating solution and then drying it. The AF coating solution consists of 45% by weight of a hexafunctional polyurethane acrylic resin prepolymer, 12% of a trifunctional acrylate monomer, 2% of an Irgacure 184 initiator, 1% of a pentafluorocarbon cyclic ether, and 40% of ethyl acetate. The AF layer is 2 µm thick.

[0069] Example 2

[0070] The only difference between this embodiment and embodiment 1 is that the biaxially oriented polypropylene layer includes a first sublayer, a second sublayer, and a third sublayer, which are stacked in sequence. The first sublayer is located on the side of the second sublayer away from the silver layer. The third sublayer is located on the side of the second sublayer closer to the silver layer. The thickness of the first sublayer, the second sublayer, and the third sublayer are all 20 μm. The pore size distribution of the micropores in the first sublayer is 0.1 μm to 0.5 μm. The pore size distribution of the micropores in the second sublayer is 0.8 μm to 1.5 μm. The pore size distribution of the micropores in the third sublayer is 3 μm to 5 μm.

[0071] Example 3

[0072] The high reflectivity optical film provided in this embodiment includes a first morphology layer, a biaxially oriented polypropylene layer, a second morphology layer, a primer layer, a silver layer, a water and oxygen barrier layer, and an AF layer stacked in sequence.

[0073] The first and second topography layers are both 0.5µm thick UV adhesive layers, onto which the moth-eye structure is formed using a stamping process. The biaxially oriented polypropylene layer is doped with inorganic filler particles, consisting of a TiO2 core encapsulated by a SiO2 coating, with a particle size distribution of 20nm to 100nm. The volume fraction of the inorganic filler particles is 10%. Micropores are distributed in the biaxially oriented polypropylene layer. The pore size distribution ranges from 2µm to 5µm, with a porosity of 32%. The biaxially oriented polypropylene layer is 50µm thick. The basecoat is acrylic, 1µm thick. The silver layer is 80nm thick. The water and oxygen barrier layer is aluminum oxide, 30nm thick. The AF layer is formed by applying an AF coating solution and then drying it. The AF coating solution consists of 45% by weight of a hexafunctional polyurethane acrylic resin prepolymer, 12% of a trifunctional acrylate monomer, 2% of an Irgacure 184 initiator, 1% of a pentafluorocarbon cyclic ether, and 40% of ethyl acetate. The AF layer is 2 µm thick.

[0074] Comparative Example 1

[0075] The optical film of this comparative example is different from that of Example 1 only in that the optical film does not include the first topography layer, the biaxially oriented polypropylene layer, the second topography layer, and the adhesive layer.

[0076] Comparative Example 2

[0077] The optical film of this comparative example is the same as the biaxially oriented polypropylene layer in Example 1.

[0078] The high reflectivity optical films of the above embodiments and comparative examples were tested for brightness and reflectivity. The test results are shown in Table 1.

[0079] Table 1 Brightness and reflectivity of high reflectivity optical films of various embodiments and comparative examples

[0080]

[0081] As can be seen from the results in Table 1, the high reflectivity optical films of Examples 1 to 3 have high brightness, and the reflectivity can reach above 98%, or even above 99%, thereby fully utilizing the light from the side light source.

[0082] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A high reflectivity optical film, characterized in that: The invention comprises a stacked biaxially oriented polypropylene layer and a silver layer, wherein the biaxially oriented polypropylene layer is doped with inorganic filler particles, the particle size of the inorganic filler particles is 20nm~400nm, and micropores are distributed in the biaxially oriented polypropylene layer, the pore size of the micropores is 0.1μm~5μm.

2. The high reflectivity optical film according to claim 1, wherein The inorganic filler particles include a TiO2 core and a SiO2 coating layer coated on the TiO2 core; And / or, the volume fraction of the inorganic filler particles in the biaxially oriented polypropylene layer is 10% to 30%; And / or, the porosity of the biaxially oriented polypropylene layer is 10% to 40%.

3. The high reflectivity optical film according to claim 1, wherein The biaxially oriented polypropylene layer includes a plurality of stacked sublayers, and the pore diameters of the micropores in different sublayers increase gradually as they approach the silver layer.

4. The high reflectivity optical film according to claim 3, wherein The biaxially oriented polypropylene layer includes a first sublayer, a second sublayer, and a third sublayer stacked in sequence, the first sublayer being located on a side of the second sublayer away from the silver layer, the third sublayer being located on a side of the second sublayer close to the silver layer, the pore diameter of the micropores in the first sublayer being 0.1 μm to 0.5 μm, the pore diameter of the micropores in the second sublayer being 0.8 μm to 1.5 μm, and the pore diameter of the micropores in the third sublayer being 3 μm to 5 μm.

5. The high reflectivity optical film according to claim 1, wherein The thickness of the biaxially oriented polypropylene layer is 10 μm to 100 μm; And / or, the thickness of the silver layer is 20nm~100nm.

6. The high reflectivity optical film according to claim 1, wherein The high reflectivity optical film further includes a first topography layer, which is disposed on a side of the biaxially oriented polypropylene layer away from the silver layer, and has a moth-eye structure.

7. The high reflectivity optical film according to any one of claims 1 to 6, wherein The high reflectivity optical film further includes a second topography layer, which is disposed on a side of the biaxially oriented polypropylene layer facing the silver layer, and has a moth-eye structure.

8. The high reflectivity optical film according to claim 7, wherein The high-reflectivity optical film further includes a primer layer, which is disposed between the second topography layer and the silver layer. The primer layer includes at least one layer selected from the group consisting of a polyurethane layer, an acrylic layer, and a cyclic olefin copolymer layer.

9. The high reflectivity optical film according to claim 8, wherein The high reflectivity optical film further includes a supporting substrate layer and an adhesive layer. The supporting substrate layer is disposed between the primer layer and the second topography layer. The adhesive layer is disposed between the supporting substrate layer and the second topography layer.

10. A backlight module, characterized in that: The invention comprises a light source, a brightness enhancement component, a diffusion film, a light guide plate and a high-reflectivity optical film according to any one of claims 1 to 9, wherein the diffusion film and the high-reflectivity optical film are respectively arranged on opposite sides of the light guide plate, the brightness enhancement component is arranged on a side of the diffusion film away from the light guide plate, and the light source is arranged on the side of the light guide plate.

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