Reflective films, reflective sheets, and backlight modules

Abstract

The present application discloses a reflective film, a reflective sheet and a backlight module. The reflective film includes the following structures stacked in sequence: a base film; a first coating, the raw materials of the first coating include by mass: 50 parts of epoxy resin; 20-50 parts of nanocellulose; 0.5-3 parts of filler; a metal oxide layer, the metal oxide layer includes one or more of aluminum oxide and titanium oxide; a metal layer, including particles containing metal elements, the metal layer is not doped, wherein the particles containing metal elements include one or more of aluminum particles, silver particles, and gold particles, wherein the thickness of the metal layer is 60nm-120nm, and the metal oxide layer is 380 nm-540nm. The reflective film of the present application can solve the problems of poor thermal stability and poor service life of the reflective film on the basis of having good reflective performance.

Description

Technical Field

[0001] The present application belongs to the field of film optical technology, and in particular relates to a reflective film, a reflective sheet and a backlight module. Background Art

[0002] The backlight module is an important component of the liquid crystal display device. After the light source of the backlight module enters the light guide plate, the light source is provided to the LCD module upward, and the downward light hits the reflective sheet, and then rebounds through the light guide plate to return to the LCD module. Therefore, a very important factor affecting the quality and quality of the backlight module is the reflection utilization rate of light.

[0003] The reflective film is an important component of the backlight module, which is used to enhance the reflection effect of light and improve the brightness and energy efficiency of the backlight module. The reflective film is usually included inside the reflective sheet, which is a key part of the reflective sheet and is used to further enhance the reflection effect of light. The reflective film in the reflective sheet plays a role in optimizing light utilization, improving brightness and energy efficiency, improving brightness uniformity, and improving contrast in the backlight module. In the related art, the weather resistance of the reflective film is poor, and light in special wavelengths can directly affect the performance of the reflective sheet and the backlight module, such as the yellowing effect, so it is urgently needed to be improved. Summary of the invention

[0004] The embodiments of the present application provide a reflective film, a reflective sheet and a backlight module to solve the problems of the reflective sheet and the backlight module, including poor thermal stability and short service life.

[0005] In a first aspect, the present application provides a reflective film, wherein the reflective film comprises the following structures stacked in sequence:

[0006] Basement membrane;

[0007] The first coating layer comprises, by weight, 50 parts of epoxy resin, 20-50 parts of nanocellulose, and 0.5-3 parts of filler;

[0008] A metal oxide layer, the metal oxide layer comprising one or more of aluminum oxide and titanium oxide;

[0009] The metal layer includes particles containing metal elements, and the metal layer is not doped; the particles containing metal elements include one or more of aluminum particles, silver particles, and gold particles, wherein the thickness of the metal layer is 60nm-120nm, and the thickness of the metal oxide layer is 380 nm-540nm.

[0010] The particle treatment can increase the surface roughness, causing the incident light to scatter in multiple directions and reduce the specular reflection on the reflective sheet surface. This can reduce glare, improve visual comfort and improve the uniformity of reflected light.

[0011] In some optional embodiments, the metal layer includes metal single substance particles, and the metal single substance particles include one or more of aluminum, silver, and gold.

[0012] In some optional embodiments, the relationship between the sum H of the thicknesses of the metal layer and the metal oxide layer, the refractive index η of the metal layer, and the wavelength λ of the ambient light incident on the metal layer is:

[0013] 2×η×H=λ / 2.

[0014] In some optional embodiments, the thickness ratio of the metal oxide layer to the metal layer is 100:(11-33).

[0015] In some optional embodiments, the raw materials of the first coating include, by mass, 50 parts of epoxy resin, 30-45 parts of nanocellulose, 0.5-3 parts of filler, 50-100 parts of solvent, 10-20 parts of sodium ethylenediaminoethanesulfonate, 0.5-1 part of ethylenediamine, and 0.5-1 part of ultraviolet absorber, wherein the solvent includes one or more of ethylene glycol monobutyl ether and a mixture of anhydrous ethanol.

[0016] In some optional embodiments, the reflectivity of the reflective film to 540nm light is ≥97%.

[0017] In some optional embodiments, the haze of the reflective film is ≤22%.

[0018] In some optional embodiments, in a reliability experiment of the reflective film, after being treated at 80 degrees for 240 hours, the chromaticity of the reflective film is 1.76±0.42, and can be optionally 1.76±0.38.

[0019] In some optional embodiments, the adhesion of the reflective film at room temperature is 4B-5B, and the adhesion range of the reliability experiment is 4B-5B under the test conditions of temperature 65 degrees, humidity 95%, and 240 hours.

[0020] In some optional embodiments, the reflective film has no corrosion phenomenon in the salt spray test, and the adhesion range after the salt spray test is 4B-5B.

[0021] In a second aspect, the present application provides a reflective sheet, comprising a substrate and a reflective film of the first aspect disposed on a surface of the substrate.

[0022] In a third aspect, the present application provides a backlight module, comprising the reflective sheet of the second aspect.

[0023] Compared with the prior art, this application has at least the following beneficial effects:

[0024] The present application selects a reflective film including the following structures stacked in sequence: a base film; a first coating layer, a metal oxide layer; a metal layer, including particles containing metal elements, and the metal layer is not doped; the first coating layer contains epoxy resin, nanocellulose and fillers, which is beneficial to improving the bonding strength between the base film and the metal oxide layer and the metal layer. The nanocellulose and fillers can improve the heat resistance of the reflective film and make the first coating layer have a certain porosity. The reason for this may be that the nanocellulose and fillers form a stable spatial network structure, so that the layer can have uniform nanopores. The filler of the layer and the arrangement with the metal oxide layer can reduce the shrinkage degree of the base film when heated, reduce the risk of thermal shrinkage of the reflective film, thereby further improving its heat resistance and service life; particles of metal elements, the metal layer is not doped, thereby improving the reflective performance of the reflective film; the reflective film has high brightness and good chromaticity as well as excellent weather resistance and thermal stability due to the combined effect, so that the reflective sheet containing the reflective film has good thermal stability and beneficial properties, especially reflectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 It is a schematic diagram of the structure of the reflective film according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the application purpose, technical solution and beneficial technical effect of the present application clearer, the present application is further described in detail in conjunction with the embodiments below. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.

[0028] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unclearly recorded range; and any lower limit can be combined with other lower limits to form an unclearly recorded range, and any upper limit can be combined with any other upper limit to form an unclearly recorded range. In addition, although not clearly recorded, each point or single value between the endpoints of the range is included in the range. Thus, each point or single value can be combined as its own lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unclearly recorded range.

[0029] In the description of the present application, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number, and the “multiple” in “one or more” means two or more than two.

[0030] The above application content of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example, enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0031] Reflective film is a film with special optical properties used to enhance the reflection effect of light. It is usually composed of multiple materials that are designed and optimized at the optical level to achieve specific reflective properties.

[0032] The reflective film is usually located below the light guide plate of the backlight module. Its function is to increase the reflection of light in the backlight module, thereby improving the efficiency of light utilization, for example, ensuring that more light can be directed to the LCD screen and reducing energy loss.

[0033] In a first aspect, the present application provides a reflective film, wherein the reflective film comprises the following structures stacked in sequence:

[0034] Basement membrane;

[0035] The first coating layer comprises, by weight, 50 parts of epoxy resin, 20-50 parts of nanocellulose, and 0.5-3 parts of filler;

[0036] A metal oxide layer, the metal oxide layer comprising one or more of aluminum oxide and titanium oxide;

[0037] The metal layer includes particles containing metal elements, and the metal layer is not doped; the particles containing metal elements include one or more of aluminum particles, silver particles, and gold particles, wherein the thickness of the metal layer is 60nm-120nm, and the thickness of the metal oxide layer is 380 nm-540nm.

[0038] In this embodiment, the particles containing metal elements in the metal layer can be processed by particle size treatment. The metal layer is not doped, which can improve the reflective performance of the reflective film.

[0039] In this embodiment, the first coating layer contains epoxy resin, nanocellulose and filler, which is beneficial to improve the bonding strength between the base film and the metal oxide layer and the metal layer. The nanocellulose and filler can improve the heat resistance of the reflective film and make the first coating layer have a certain porosity. The reason may be that the nanocellulose and filler form a stable spatial network structure, so that the layer can have uniform nanopores. The filler of the first coating layer and the setting of the metal oxide layer can reduce the shrinkage degree of the base film when heated, reduce the risk of thermal shrinkage of the reflective film, thereby further improving its heat resistance and service life.

[0040] The metal oxide layer and the metal layer each have a certain reflective effect. The two layers cooperate with each other. The comprehensive reflective film has high brightness and good chromaticity. At the same time, it has excellent weather resistance and thermal stability, which makes the reflective sheet containing the reflective film have good thermal stability and excellent reflectivity.

[0041] When the reflective film of the present application exists in a reflective sheet and is used in a backlight module, it can make the light more evenly distributed on the light guide plate. The increased reflected light can improve the contrast, while increasing the service life and reflectivity of the reflective sheet.

[0042] Figure 1 The reflective film according to the embodiment of the present application is shown.

[0043] See also Figure 1 The reflective film includes the following structures stacked in sequence: a base film 100, a first coating layer 200, a metal oxide layer 300, and a metal layer 400.

[0044] In some optional embodiments, the diameter of the particles containing metal elements is preferably selected to be 5-100 nm, or can be determined according to the actual requirements of the backlight module.

[0045] In some optional embodiments, the thickness of the base film is 20 μm-250 μm. Optionally, the thickness of the base film can be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm.

[0046] In some embodiments, the base film includes one or more of a polyester (PET) film, an olefin film, a polyvinyl alcohol (PC) film, a polyetheretherketone film, and a polyimide film.

[0047] According to the embodiments of the present application, the above materials can be used as base films. In particular, for transparent polyester (PET) films, a thickness range of 23 microns to 250 microns is generally selected, the light transmittance is required to be greater than 85%, and the haze is less than 1.5%. For example, the base film QY01 of Yihua Dongli Polyester Film Co., Ltd. can be used.

[0048] In some embodiments, the base film may include a PET substrate containing a pre-coating layer. The material of the pre-coating layer may be polyurethane, acrylic resin, or polyester material. The thickness of the pre-coating layer is less than 0.3 micrometers.

[0049] In some optional embodiments, the thickness of the metal layer is 60 nm-120 nm, and the thickness of the metal oxide layer is 380 nm-540 nm.

[0050] According to the embodiment of the present application, the metal oxide layer also has a certain reflective effect. When the reflective film is used at high temperature, part of the organic polymer in the first coating layer may diffuse into the metal layer. The metal oxide layer has a buffering effect on the one hand, and enhances the bonding force between the metal layer and the first coating layer on the other hand, thereby reducing the cost. In summary, the cost is further reduced while taking into account the performance.

[0051] The metal oxide layer and the metal layer can be prepared by vacuum evaporation, sputtering, arc plasma plating, and ion plating, and the constituent metals are not particularly limited. For example, other metals include gold, silver, and the like.

[0052] According to the embodiment of the present application, by controlling the effective thickness of the metal layer within the above range, the reflectivity of the reflective film can be effectively provided. In the actual preparation process, the metal layer is easily oxidized. Considering that after the coating is completed, the metal layer has a certain oxidation rate.

[0053] In some optional embodiments, a metal protective layer is provided on the surface of the metal layer. According to research, it is found that the coating thickness is less than 20nm, and its effective metal layer is less than 30%. In some embodiments, the metal protective layer includes resin. The resin includes one or more of thermoplastic resins and thermosetting resins. For example, amino resins, acrylic resins, acrylic-styrene copolymers, polyester resins, vinyl chloride resins, vinyl acetate resins, polyvinyl butanol, polyurethane resins, melamine resins, urea-melamine resins, polyamide resins, etc., alone or in combination thereof, are used.

[0054] In some embodiments, when preparing the metal protective layer, a micro-concave anilox roller is used for reverse coating. During preparation, the drying temperature is 125-145° C. The unique stacking method of the metal layer requires the coating to meet its stacking height and fill its gaps.

[0055] In some optional embodiments, in order to further improve the reflectivity of the reflective film on the basis of saving costs and strengthening the adhesion between the reflective films, the thickness ratio of the metal oxide layer to the metal layer is 100:(11-33). Optionally, the thickness ratio of the metal oxide layer to the metal layer can be 100:11, 100:13, 100:15, 100:17, 100:19, 100:21, 100:23, 100:25, 100:27, 100:29, 100:31, 100:33.

[0056] In some optional embodiments, the relationship between the sum H of the thicknesses of the metal layer and the metal oxide layer, the refractive index η of the metal layer, and the wavelength λ of the ambient light incident on the metal layer is:

[0057] 2×η×H=λ / 2.

[0058] Generally speaking, the refractive index of silver is usually in the visible light range (wavelength of about 400 to 700 nanometers) and is a common research object. Its refractive index is about 0.145. The wavelength λ of ambient light can generally be 540nm. Therefore, the range of H can be about 930 nanometers, but the components in the metal oxide layer, for example, the refractive index of aluminum oxide (Al2O3) is about 1.6 to 1.7, and the refractive index of titanium oxide (TiO2) is about 2.3 to 2.6, so the range of H can be greater than 84 nanometers; according to the selection of the metal layer and the metal oxide layer material, the thickness of H can be selectively changed.

[0059] The sum of the thicknesses H of the metal layer and the metal oxide layer, the refractive index η of the metal layer, and the wavelength λ of the ambient light incident on the metal layer satisfy the above relationship. When the ambient light passes through the metal layer, part of the light will be reflected on the surface of the metal layer, and the other part of the light will pass through the metal layer and enter the metal reflective layer. These two kinds of reflected light may interfere with each other to a certain extent during the transmission process, thereby reducing the reflected ambient light emitted from the base film side and affecting the display effect.

[0060] In some optional embodiments, the thickness of the first coating layer is 1 μm-4 μm. The thickness of the first coating layer may be 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, or 4.0 μm.

[0061] In some optional embodiments, the raw materials of the first coating layer include, by weight: epoxy resin: 50 parts; nanocellulose: 20-50 parts; filler: 0.5-3 parts.

[0062] The raw materials of the first coating layer are controlled to include, by weight, 50 parts of epoxy resin, 20-50 parts of nanocellulose, and 0.5-3 parts of filler, which can further improve the bonding strength between the base film and the metal oxide layer and the metal layer. The nanocellulose and filler can improve the heat resistance of the reflective film and make the first coating layer have a certain porosity, thereby reducing the risk of heat shrinkage of the reflective film, thereby further improving its heat resistance and service life.

[0063] In some optional embodiments, the filler includes one or more of aluminum oxide, zinc oxide, silicon oxide, titanium oxide, and zirconium oxide.

[0064] In some optional embodiments, nanocellulose may include at least one of cellulose nanofibers (Cellulose nanofibrils, CNF, also known as nanofibrillated cellulose or microfibrillated cellulose), cellulose nano whiskers (Cellulose nanocrystals, CNC, also known as cellulose nanocrystals, nanocrystalline cellulose) and bacterial nanocellulose (Bacterial nanocellulose, BNC, also known as bacterial cellulose or microbial cellulose), and cellulose nano whiskers may be selected. Cellulose nano whiskers may have a higher degree of crystallinity and a lower hydrophilicity, which is beneficial for the raw material to absorb moisture during storage and preparation, resulting in an impact on the performance of the reflective film.

[0065] In some embodiments, the nanocellulose comprises modified nanocellulose, alternatively referred to as modified nanocellulose.

[0066] The modified nanocellulose includes a modification group. In some embodiments, the modification group includes at least one of an amino group, a carboxylic acid group, an aldehyde group, a sulfonic acid group, a boric acid group, and a phosphoric acid group, and optionally includes at least one of a sulfonic acid group, a boric acid group, and a phosphoric acid group.

[0067] When nanocellulose has the above-mentioned specific modified groups, it can be better combined with the filler and the metal oxide layer, which can effectively improve the heat resistance and stability of the reflective film. On the other hand, it is also beneficial for nanocellulose and fillers to build a more stable spatial network structure, which is beneficial for reserving an appropriate amount of pores, and can reduce the degree of shrinkage of the base film when heated, reduce the risk of thermal shrinkage of the reflective film, thereby further improving its heat resistance and service life.

[0068] In addition, the modified groups can ensure that the coating slurry has a suitable viscosity, which is more conducive to coating, thereby also improving the production efficiency of the isolation film and the uniformity of the coating.

[0069] In some optional embodiments, the raw materials of the first coating include, by mass, 50 parts of epoxy resin, 30-45 parts of nanocellulose, 0.5-3 parts of filler, 50-100 parts of solvent, 10-20 parts of sodium ethylenediaminoethanesulfonate, 0.5-1 part of ethylenediamine, and 0.5-1 part of ultraviolet absorber, wherein the solvent includes one or more of ethylene glycol monobutyl ether and a mixture of anhydrous ethanol.

[0070] Furthermore, the epoxy resin is selected to have a light transmittance greater than 85%, which is beneficial to further improve the light transmittance and brightness and reduce the impact on the optical properties of the substrate.

[0071] In some optional embodiments, the reflectivity of the reflective film to 540nm light is ≥97%.

[0072] In some optional embodiments, the haze of the reflective film is ≤22%.

[0073] In some optional embodiments, the chromaticity of the reflective film is 1.76±0.42, and optionally 1.76±0.38, when the reflective film is treated at 80 degrees for 240 hours in a reliability experiment.

[0074] In some optional embodiments, the adhesion of the reflective film at room temperature is 4B-5B, and the adhesion range of the reliability test is 4B-5B under the test conditions of temperature 65 degrees, humidity 95%, and 240 hours.

[0075] In some optional embodiments, the reflective film has no corrosion phenomenon in the salt spray test, and the adhesion range after the salt spray test is 4B-5B.

[0076] In a second aspect, the present application provides a reflective sheet, comprising a substrate and a reflective film of the first aspect disposed on a surface of the substrate.

[0077] In a third aspect, the present application provides a backlight module, comprising the reflective sheet of the second aspect. Example

[0078] The following examples describe the disclosure of the present application in more detail, and these examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available. For example, the epoxy resin used in the examples of the present application can be derived from the NPEL-128E model of Nan Ya Plastics Industrial Co., Ltd. Example 1

[0079] The embodiment of the present application provides a reflective film, which includes the following structures stacked in sequence:

[0080] Base film: 40μm thick, made of PET, with a light transmittance of 95% and a haze of 1.5%;

[0081] The first coating layer comprises raw materials of the first coating layer, which are calculated by weight: 50 parts of epoxy resin, 40 parts of nanocellulose, 1 part of filler, 80 parts of solvent, 10 parts of sodium ethylenediaminoethanesulfonate, 1 part of ethylenediamine, and 0.8 parts of ultraviolet absorber, wherein the ultraviolet absorber is 2,4-dihydroxybenzophenone, wherein the solvent comprises a mixture of ethylene glycol monobutyl ether and anhydrous ethanol in a weight ratio of 1:1, and the filler is aluminum oxide and titanium oxide; the transmittance of the first coating layer is 82%, the haze is ≤5%, and the thickness of the first coating layer is 2.0 μm.

[0082] A metal oxide layer including aluminum oxide and titanium oxide in a mass ratio of 1:1;

[0083] The metal layer is a silver layer, the surface of which includes particles containing metal elements. The metal layer is not doped and has a thickness of 100 nm.

[0084] The specific parameters are shown in Table 1.

[0085] Example 2 to Example 3

[0086] The differences between Example 2 and Example 3 and Example 1 are as follows: the thicknesses of the metal layer and the metal oxide layer are different, as shown in Table 1. Example 4

[0087] Example 4 is different from Example 1 in that the raw materials of the first coating include, by mass, 50 parts of epoxy resin, 30 parts of nanocellulose, and 2 parts of filler. Example 5

[0088] Example 5 is different from Example 1 in that the raw materials of the first coating include, by mass, 50 parts of epoxy resin, 45 parts of nanocellulose, and 0.5 parts of filler. Example 6

[0089] Example 6 is different from Example 1 in that the raw materials of the first coating include, by mass, 50 parts of epoxy resin, 40 parts of nanocellulose, and 3 parts of filler.

[0090] Comparative Example 1

[0091] The difference between this comparative example and the embodiment is that no metal oxide layer is provided and the thickness of the metal layer is 480 nm.

[0092] Comparative Example 2

[0093] The difference between this comparative example and the embodiment is that the raw materials of the first coating layer include, by mass, 90 parts of epoxy resin and 1 part of filler.

[0094] Comparative Example 3

[0095] The difference between this comparative example and the embodiment is that the raw materials of the first coating layer include, by mass, 51 parts of epoxy resin and 40 parts of nanocellulose.

[0096] Test Section Reflective film performance test:

[0097] Chromaticity detection: The reflective films prepared in the examples and comparative examples were tested according to the following experimental conditions as shown in Table 1. The chromaticity b of the substrate was tested using a Shimadzu UV-spectrophotometer 2600i chromaticity tester. The test conditions are shown in Table 1.

[0098]

[0099] Reflectivity test: Use UV-2600i UV-visible spectrophotometer for detection.

[0100] Brightness test: A reflective film with a size of 155mm×68mm was used for brightness comparison with an existing reflective film. The test voltage of the backlight module was 19V, the current was 0.04A, the brightness increase was - (brightness - 8560) / 8560, and the name of the brightness test equipment was the BM-7 colorimetric brightness tester produced by Japan's TOPCON company. The thickness and brightness of the backlight module were tested after running for 10 hours.

[0101] Haze test: Test instrument name: Japan Densho Haze Meter NDH-5000, test standard: ASTM D1003.

[0102] Adhesion test:

[0103] The test and judgment standards according to the 100-grid test method are shown in GB / T9286-1998, and the test conditions are shown in Table 2.

[0104]

[0105] Salt spray test: Test equipment: Salt spray test machine. Test conditions: The spray conditions are that the test room temperature is set at 35°C, the temperature in the pressure barrel is 47°C, 4500ML of water is mixed with 500g of sodium chloride and then 5000ML of water is added; after 240 hours, the functional test needs to meet the requirements.

[0106] The test results are shown in Table 3.

[0107] From the results in Table 3, it can be seen that the reflective film prepared in the embodiment of the present application has high high temperature resistance and good service life. The reflectivity of the reflective film to 540nm light is ≥97%; the haze of the reflective film is ≤22%; the chromaticity of the reflective film in the high temperature (80 degrees, 240 hours) reliability test of the reflective film is 1.76±0.38; the adhesion of the reflective film at room temperature is 4B-5B, and the adhesion range of the reliability test under the test conditions of temperature 65 degrees, humidity 95%, and 240 hours is 4B-5B; the performance is far better than the comparative example.

[0108] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

[0109]

Claims

1. A reflective film, characterized in that: The reflective film includes the following structures stacked in sequence: Basement membrane; The first coating layer comprises, by weight, 50 parts of epoxy resin, 20-50 parts of nanocellulose, and 0.5-3 parts of filler; A metal oxide layer, wherein the metal oxide layer comprises one or more of aluminum oxide and titanium oxide; The metal layer includes particles containing metal elements, and the metal layer is not doped, wherein the particles containing metal elements include one or more of aluminum particles, silver particles, and gold particles, wherein the thickness of the metal layer is 60nm-120nm, and the metal oxide layer is 380 nm-540nm.

2. The reflective film according to claim 1, characterized in that: The relationship between the sum of the thicknesses H of the metal layer and the metal oxide layer, the refractive index η of the metal layer, and the wavelength λ of the ambient light incident on the metal layer is: 2×η×H=λ / 2.

3. The reflective film according to claim 1, characterized in that: The thickness ratio of the metal oxide layer to the metal layer is 100:(11-33).

4. The reflective film according to claim 1, characterized in that The raw materials of the first coating are calculated by weight Including: epoxy resin: 50 parts, nanocellulose: 30-45 parts; filler: 0.5-3 parts; Solvent: 50 parts to 100 parts, sodium ethylenediaminoethanesulfonate: 10 parts to 20 parts, ethylenediamine: 0.5 parts to 1 parts, ultraviolet absorber: 0.5 parts to 1 parts, wherein the solvent comprises one or more of ethylene glycol monobutyl ether and anhydrous ethanol mixture.

5. The reflective film according to claim 1, characterized in that: The reflective film satisfies at least one of the following conditions: The reflectivity of the reflective film to 540nm light is ≥97%, The haze of the reflective film is ≤22%, The reliability test of the reflective film was conducted at 80 degrees for 240 hours. The chromaticity of the reflective film was 1.76±0.

42. The reflective film has a room temperature adhesion of 4B-5B, and the reliability test has an adhesion range of 4B-5B under the test conditions of 65 degrees at a temperature of 65 degrees and a humidity of 95% for 240 hours; The reflective film has no corrosion phenomenon in the salt spray test, and the adhesion range after the salt spray test is 4B-5B.

6. A reflective sheet, characterized in that: It comprises a substrate and a reflective film as claimed in any one of claims 1 to 5 arranged on the surface of the substrate.

7. A backlight module, characterized in that: Includes the reflector sheet as claimed in claim 6.

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