Layered coating type reflective film and edge-lit backlight module

Abstract

The present application relates to a kind of layered coating type reflective film and side entry backlight module, it is related to optical film technical field.Wherein, the layered coating type reflective film includes reflective substrate and first coating and second coating sequentially stacked on the reflective substrate, the first coating at least includes mixed particle size polymer particles, the second coating at least includes functional material, the functional material includes one-dimensional tubular carrier and refractive index 1.6 above metal oxide nanoparticles loaded on the one-dimensional tubular carrier, and the functional material in the second coating side away from the first coating content is higher than the content of side close to the first coating.The layered coating type reflective film of the present application can realize high brightness while having excellent anti-absorption performance, so that the side entry backlight module can eliminate appearance defects such as top white, and improve optical performance such as brightness.

Description

Technical Field

[0001] This invention relates to the field of optical film technology, and in particular to a layered coating type reflective film and a side-lit backlight module. Background Technology

[0002] Small and medium-sized displays are widely used in mobile phones, tablets, laptops, automotive displays, smart wearables, and other terminal devices. They often employ edge-lit backlight modules to achieve a thinner and lighter design. In edge-lit backlight modules, a reflective film is placed close to the light guide plate to reflect leaked light back to the light guide plate, improving light utilization. However, when the untreated reflective film is in direct contact with the light guide plate, it is prone to uneven assembly and bonding, localized gap variations, and other problems due to physical adsorption. This can lead to appearance defects such as white spots, shadows, mottled patterns, or uneven brightness.

[0003] To address this issue, a coating process is typically applied to the surface of the reflective film to form an anti-adhesion layer. However, this coating process introduces additional light loss, leading to a decrease in the overall optical brightness of the reflective film. This contradicts the ongoing pursuit of higher reflectivity and brightness in reflective film technology, as well as the demand for high brightness, low power consumption, and superior image quality in display products. Therefore, developing a reflective film that balances anti-adhesion performance with high brightness holds significant promise and will also contribute to the evolution of small- and medium-sized display products towards thinner, lighter, and higher-performance designs. Summary of the Invention

[0004] Therefore, it is necessary to provide a layered coating reflective film and a side-lit backlight module to address the above problems. The layered coating reflective film has excellent anti-adsorption properties and can achieve high brightness, enabling the side-lit backlight module to eliminate appearance defects such as top white and improve optical performance such as brightness.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a layered coating type reflective film, comprising a reflective substrate and a first coating and a second coating sequentially stacked on the reflective substrate, wherein the first coating comprises at least polymer particles of mixed particle sizes, and the second coating comprises at least a functional material, wherein the functional material comprises a one-dimensional tubular carrier and metal oxide nanoparticles with a refractive index of 1.6 or higher loaded on the one-dimensional tubular carrier, and the content of the functional material on the side of the second coating away from the first coating is higher than the content on the side closer to the first coating.

[0006] In one embodiment, the first coating liquid used for the first coating, by mass fraction, comprises 3 wt% to 6 wt% polymer particles, 38 wt% to 42 wt% adhesive, 3.8 wt% to 4.2 wt% curing agent, 0.5 wt% to 1 wt% antistatic agent, and the balance being solvent;

[0007] And / or, the thickness of the first coating is 20μm~40μm.

[0008] In one embodiment, the polymer particles include small-diameter polymer particles with a particle size of 3 μm to 10 μm and large-diameter polymer particles with a particle size of 20 μm to 34 μm, wherein the mass ratio of the small-diameter polymer particles to the large-diameter polymer particles is 1:1 to 3:1.

[0009] In one embodiment, the polymer particles in the first coating liquid are selected from at least one of polyethylene terephthalate particles, polymethyl methacrylate particles, polybutyl methacrylate particles, polyamide particles, and polyurethane particles.

[0010] And / or, the adhesive in the first coating liquid is selected from at least one of acrylic resin adhesive, polycarbonate resin adhesive, polyurethane resin adhesive, and polyimide resin adhesive;

[0011] And / or, the curing agent in the first coating liquid is selected from at least one of isocyanate, epoxy resin, methylphenol resin, and dicyandiamide;

[0012] And / or, the antistatic agent in the first coating liquid is selected from lithium trifluoromethanesulfonate;

[0013] And / or, the solvent in the first coating solution is selected from at least one of ethyl acetate, butyl acetate, and acetone.

[0014] In one embodiment, the one-dimensional tubular support is selected from at least one of carbon nanotube supports, boron nitride nanotube supports, and molybdenum disulfide nanotube supports;

[0015] And / or, the metal oxide nanoparticles are selected from at least one of titanium dioxide nanoparticles, zirconium oxide nanoparticles, and zinc oxide nanoparticles.

[0016] In one embodiment, the second coating is a UV coating;

[0017] And / or, the thickness of the second coating is 2μm~6μm.

[0018] In one embodiment, the second coating liquid used in the second coating comprises, by mass fraction, 0.1 wt% to 0.5 wt% of functional material, 48 wt% to 52 wt% of oligomer, 4.5 wt% to 5.7 wt% of photoinitiator, and 42 wt% to 46 wt% of UV diluent.

[0019] In one embodiment, the oligomer in the second coating liquid is selected from at least one of polyacrylate oligomers, polyether acrylate oligomers, polysiloxane acrylate oligomers, and polyamino acrylate oligomers.

[0020] And / or, the photoinitiator in the second coating liquid is selected from at least one of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-methylphenylpropane-1-one, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide and xylene ketone;

[0021] And / or, the UV diluent in the second coating liquid is selected from at least one of methyl acrylate, ethyl acrylate, butyl acrylate and isobornyl acrylate.

[0022] In one embodiment, the reflective substrate is selected from at least one of polyester film and polypropylene film;

[0023] And / or, the thickness of the reflective substrate is 50μm~150μm.

[0024] A side-lit backlight module includes the aforementioned layered coating reflective film.

[0025] In this invention, polymer particles of mixed sizes in the first coating form a microscopic protrusion structure, acting as a physical separator to prevent the reflective film from adsorbing onto the light guide plate, thus achieving excellent anti-adsorption performance. Simultaneously, functional materials in the second coating are enriched on the coating surface, maximizing the exposure of metal oxide nanoparticles with a refractive index of 1.6 or higher in the light path to exert their high refractive index light scattering effect, thereby significantly improving brightness. Furthermore, the synergistic effect of the stacked structure composed of the first and second coatings avoids the problem of mutual constraint between anti-adsorption performance and high brightness in the coating, enabling the reflective film to achieve high brightness while possessing excellent anti-adsorption performance. Therefore, side-lit backlight modules using the layered coating reflective film described in this invention can eliminate appearance defects such as top whitening and improve optical performance such as brightness, which is beneficial for promoting the evolution of small and medium-sized display products towards thinner, lighter, and higher-performance designs. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 Electron microscope image of the light guide plate of the layered coating type reflective film of Example 1;

[0028] Figure 2 Electron microscope image of the light guide plate of the layered coating type reflective film of Example 2;

[0029] Figure 3 Electron microscope image of a light guide plate with a layered coating type reflective film applied as in Comparative Example 5. Detailed Implementation

[0030] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0032] 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. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0033] The layered coating type reflective film provided by the present invention includes a reflective substrate and a first coating and a second coating sequentially stacked on the reflective substrate.

[0034] The choice of reflective substrate is not particularly limited and can be selected from at least one of polyester film (PET film) and polypropylene film (PP film), with PET film being preferred. The thickness of the reflective substrate can be selected according to actual application requirements, typically 50μm to 150μm, such as 50μm, 75μm, or 150μm.

[0035] Specifically, the first coating comprises at least polymer particles of mixed sizes. Larger-sized polymer particles form raised structures on the surface of the first coating, acting as physical spacers to prevent large-area close contact between the reflective film and the light guide plate, thus avoiding appearance defects such as white spots and shadows caused by physical adsorption. Smaller-sized polymer particles fill the gaps between the larger particles, increasing the density of raised areas per unit area and forming a more complex micro-rough surface, further reducing the contact area and enhancing the diffuse reflection effect of light, thus reducing light loss. Therefore, through the synergistic effect of different particle sizes, the first coating achieves excellent anti-adsorption performance at a relatively low coating thickness.

[0036] In the first coating, the mass fraction of the polymer particles is preferably 5% to 15%, and the mass fraction of the polymer particles in the first coating can be controlled by controlling the content of polymer particles in the coating liquid.

[0037] In some embodiments, the first coating is made using a first coating liquid by mass fraction. The first coating liquid comprises 3 wt% to 6 wt% polymer particles, 38 wt% to 42 wt% adhesive, 3.8 wt% to 4.2 wt% curing agent, and 0.5 wt% to 1 wt% antistatic agent, with the balance being solvent. The first coating is obtained after the solvent in the first coating liquid evaporates. Specifically, the polymer particles, adhesive, curing agent, and antistatic agent can be dispersed in a solvent, ultrasonically dispersed for 0.5 h to 2 h, and stirred evenly to obtain the first coating liquid. Then, the first coating liquid is applied to the surface of the reflective substrate and heated at 100°C to 120°C for 1 min to 3 min to allow the adhesive to fully crosslink and the solvent to completely evaporate, thus obtaining the first coating.

[0038] The polymer particles are selected from at least one of polyethylene terephthalate (PET) particles, polymethyl methacrylate (PMMA) particles, polybutyl methacrylate (PBMA) particles, polyamide (PA) particles, and polyurethane (PU) particles; the adhesive is selected from at least one of acrylic resin adhesives, polycarbonate resin adhesives, polyurethane resin adhesives, and polyimide resin adhesives; the curing agent is selected from at least one of isocyanate, epoxy resin, methylphenol resin, and dicyandiamide; the antistatic agent is selected from lithium trifluoromethanesulfonate, including at least one of lithium bis(trifluoromethanesulfonyl)imide and lithium trifluoromethanesulfonate; and the solvent is selected from at least one of ethyl acetate, butyl acetate, and acetone.

[0039] It is understandable that in polymer particles with mixed particle sizes, polymer particles of different sizes can be selected from the same material or from different materials.

[0040] Furthermore, the polymer particles include small-diameter polymer particles with a particle size of 3μm to 10μm and large-diameter polymer particles with a particle size of 20μm to 34μm, and preferably the mass ratio of the small-diameter polymer particles to the large-diameter polymer particles is 1:1 to 3:1, which can better utilize the two types of polymer particles to form a micro-rough surface, thereby better improving the anti-adsorption performance.

[0041] In order to obtain excellent anti-adsorption performance while avoiding excessive light loss due to excessive thickness of the first coating, the thickness of the first coating is preferably 20μm~40μm.

[0042] Specifically, the second coating includes at least a functional material, comprising a one-dimensional tubular carrier and metal oxide nanoparticles with a refractive index of 1.6 or higher loaded on the one-dimensional tubular carrier. The content of the functional material on the side of the second coating furthest from the first coating is higher than that on the side closer to the first coating. The metal oxide nanoparticles, as high-refractive-index light scatterers, effectively suppress agglomeration when loaded onto the one-dimensional tubular carrier to form a "point-line" composite structure, enabling them to effectively scatter incident light back towards the light guide plate. Furthermore, the functional material is further enriched on the surface of the second coating, maximizing the exposure of the metal oxide nanoparticles in the optical path and reducing light absorption and scattering losses caused by the coating. Thus, through the synergistic effect of suppressing agglomeration on the one-dimensional tubular carrier and reducing light loss through surface enrichment, the light scattering efficiency of the metal oxide nanoparticles can be fully utilized, effectively improving the optical brightness of the reflective film.

[0043] Optionally, the one-dimensional tubular support is selected from at least one of carbon nanotube (CNT) supports, boron nitride nanotube (BNNT) supports, and molybdenum disulfide nanotube (MoS2NT) supports, preferably a CNT support, and more preferably a multi-walled CNT support.

[0044] Because CNTs, in addition to acting as a carrier to inhibit the aggregation of metal oxide nanoparticles, also have multiple functions. First, CNTs have excellent electrical conductivity; the conductive network they form can dissipate static charge in a timely manner, significantly reducing the surface resistivity of the reflective film, thereby giving the reflective film excellent antistatic properties, preventing the static adsorption of dust particles, and ensuring optical quality. Second, CNTs have high tensile strength and aspect ratio, and can form a three-dimensional network skeleton in the second coating, thereby improving the tensile strength of the reflective film and enabling it to maintain better structural integrity when subjected to external impacts or temperature changes, thus ensuring the overall service life of the reflective film. Furthermore, as a high-temperature resistant material, CNTs can maintain the stability of its mechanical properties and chemical structure even at high temperatures. Applying them to the coating of reflective films can effectively reduce the thermal shrinkage rate of the reflective substrate under high-temperature conditions.

[0045] Optionally, the metal oxide with a refractive index of 1.6 or higher is selected from at least one of titanium dioxide nanoparticles, zirconium oxide nanoparticles, and zinc oxide nanoparticles, preferably titanium dioxide nanoparticles.

[0046] It should be noted that the content of titanium dioxide in the functional material can be adjusted as needed to achieve the preset scattering effect. Preferably, the mass fraction of titanium dioxide nanoparticles in the functional material is 84wt%~99wt%.

[0047] Taking the preferred CNTs carrier and titanium dioxide nanoparticles as an example, titanium sources such as tetrabutyl titanate can be hydrolyzed and polycondensed to nucleate and grow on the surface of CNTs. Through CO-Ti chemical bonds, titanium dioxide nanoparticles are uniformly coated on the surface of CNTs, realizing the in-situ growth and firm anchoring of titanium dioxide nanoparticles on the surface of CNTs, and obtaining functional materials.

[0048] Since UV curing can produce ultra-thin coatings, reduce light loss, and facilitate the enrichment of functional materials on the surface, in some embodiments, the second coating is preferably a UV coating, and the thickness of the second coating is preferably 2μm to 6μm.

[0049] In the second coating, the mass fraction of the functional material is preferably 0.1wt% to 0.5wt%, and the mass fraction of the functional material in the second coating can be controlled by controlling the content of the functional material in the coating liquid.

[0050] In some embodiments, the second coating is made using a second coating liquid, by mass fraction. The second coating liquid comprises 0.1 wt% to 0.5 wt% of functional materials, 48 ​​wt% to 52 wt% of oligomers, 4.5 wt% to 5.7 wt% of photoinitiator, and 42 wt% to 46 wt% of UV diluent, and is obtained by UV curing. Specifically, the functional materials, oligomers, photoinitiator, and UV diluent are first mixed and ultrasonically dispersed for 0.5 h to 1 h to obtain the second coating liquid. Then, the second coating liquid is applied to the surface of the first coating away from the reflective substrate, and the second coating is formed by UV curing. Preferably, the UV curing energy is 200 mJ / cm². 2 ~1000mJ / cm 2 .

[0051] The oligomer is selected from at least one of polyacrylate oligomers, polyether acrylate oligomers, polysiloxane acrylate oligomers, and polyamino acrylate oligomers; the photoinitiator is selected from at least one of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-methylphenylpropane-1-one, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and xylene ketone; and the UV diluent is selected from at least one of methyl acrylate, ethyl acrylate, butyl acrylate, and isobornyl acrylate.

[0052] Therefore, the present invention, through the synergistic effect of the stacked structure composed of the first coating and the second coating, can avoid the problem of mutual restriction between the anti-adsorption performance and high brightness in the coating, so that the reflective film can achieve high brightness while having excellent anti-adsorption performance.

[0053] This invention also provides a side-lit backlight module, including the aforementioned layered coating reflective film. Because the reflective film of this invention possesses excellent anti-adhesion properties while achieving high brightness, the side-lit backlight module using the layered coating reflective film of this invention can eliminate appearance defects such as top white and improve optical performance such as brightness. This is beneficial for promoting the evolution of small and medium-sized display products towards thinner, lighter, and higher-performance designs.

[0054] The technical solution of the present invention will be further described below through specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without specified manufacturers are all commercially available conventional products.

[0055] Example 1

[0056] 0.1 g of CNTs (multi-walled, 30 nm–50 nm in diameter), 10 mL of concentrated HNO3, and 30 mL of concentrated H2SO4 were placed in a three-necked flask and refluxed magnetically in a 60 °C water bath for 1.5 hours. After cooling to room temperature, the mixture was diluted with a large amount of deionized water until the supernatant was neutral. The mixture was centrifuged at 8000 rpm for 10 min, and the supernatant was discarded. The resulting acid-treated CNT solid was dried in a 60 °C oven for 12 hours to obtain acid-oxidized CNTs. Then, 0.05 g of the acid-oxidized CNTs was added to 50 mL of anhydrous ethanol and ultrasonically dispersed for 20 min to obtain a CNT dispersion.

[0057] 10.7 mL of benzyl alcohol and 0.72 mL of deionized water were poured into a beaker and magnetically stirred for 10 minutes to obtain a benzyl alcohol-deionized water mixed solution. A three-necked flask was placed in an ice-water bath with magnetic stirring turned on. Then, the CNT dispersion and the benzyl alcohol-deionized water mixed solution were slowly poured into the three-necked flask separately, maintaining the ice bath, and stirred for 30 minutes to ensure thorough mixing of the CNTs, benzyl alcohol, and deionized water, yielding the first solution.

[0058] 10 mL of anhydrous ethanol and 3.4 mL of tetrabutyl titanate were placed in a beaker and slowly stirred with a glass rod until homogeneous. The beaker was then placed in an ice-water bath to obtain a second solution. This second solution was placed in a constant-pressure dropping funnel and slowly added dropwise to the first solution at a rate of 1-2 drops / second. The mixture was stirred in an ice bath for 2 hours, then the ice-water bath was removed, and the mixture was stirred at room temperature for 8 hours. After filtration, the mixture was dried in a 70°C oven for 36 hours to obtain a solid sample. The solid sample was then ground and placed in a ceramic crucible in a muffle furnace. Calcination was performed under an argon atmosphere, with the temperature increased to 350°C at a rate of 3°C / min and held for 1.5 hours to obtain the functional material, which includes a CNT support and titanium dioxide nanoparticles loaded on the CNT support.

[0059] By weight, 3 parts of small-particle-size PMMA polymer particles with a particle size of 8 μm, 1.5 parts of large-particle-size PU polymer particles with a particle size of 25 μm, 40 parts of acrylic resin adhesive, 4 parts of isocyanate, and 0.7 parts of lithium bis(trifluoromethanesulfonyl)imide were dispersed in 50.8 parts of ethyl acetate and ultrasonically dispersed for 1 hour to obtain the first coating solution. This coating solution was then coated onto the surface of a 75 μm thick PET film and cured in an oven at 110°C for 2 minutes to form the first coating layer.

[0060] By weight, 0.3 parts of the above functional material, 50 parts of acrylate oligomer, 4.8 parts of 1-hydroxycyclohexylphenyl ketone, and 44.9 parts of methyl acrylate were mixed and ultrasonically dispersed for 0.5 h to obtain a second coating liquid. This coating liquid was applied to the surface of the first coating layer and UV cured at an energy of 460 mJ / cm² to form a second coating layer, thus obtaining a layered coating type reflective film.

[0061] Example 2

[0062] The only difference between Example 2 and Example 1 is that the amount of small-particle-size PMMA polymer particles with a particle size of 8 μm is 2.3 parts, and the amount of large-particle-size PU polymer particles with a particle size of 25 μm is 2.2 parts.

[0063] Example 3

[0064] The only difference between Example 3 and Example 1 is that the amount of small-particle-size PMMA polymer particles with a particle size of 8 μm is 3.3 parts, and the amount of large-particle-size PU polymer particles with a particle size of 25 μm is 1.2 parts.

[0065] Example 4

[0066] The only difference between Example 4 and Example 1 is that in the second coating liquid, the amount of functional material is 0.1 parts, the amount of acrylate oligomer is 50 parts, the amount of 1-hydroxycyclohexylphenyl ketone is 4.8 parts, and the amount of methyl acrylate is 45.1 parts.

[0067] Example 5

[0068] The difference between Example 5 and Example 1 is that in the second coating liquid, the amount of functional material is 0.5 parts, the amount of acrylate oligomer is 50 parts, the amount of 1-hydroxycyclohexylphenyl ketone is 4.8 parts, and the amount of methyl acrylate is 44.7 parts.

[0069] Example 6

[0070] The only difference between Example 6 and Example 1 is that the carbon nanotubes are single-walled carbon nanotubes (with a diameter of 1 nm to 2 nm).

[0071] Example 7

[0072] The only difference between Example 7 and Example 1 is that the carbon nanotubes are boron nitride carbon nanotubes.

[0073] Example 8

[0074] The only difference between Example 8 and Example 1 is that the carbon nanotubes are molybdenum disulfide nanotubes.

[0075] Example 9

[0076] The only difference between Example 9 and Example 1 is that 3.4 mL of tetrabutyl titanate was replaced with 2.2 g of zinc acetate dihydrate, and the final nanoparticles obtained were zinc oxide nanoparticles.

[0077] Example 10

[0078] The only difference between Example 10 and Example 1 is that 3.4 mL of tetrabutyl titanate was replaced with 3.6 mL of tetrabutyl zirconate, and the final nanoparticles obtained were zirconium oxide nanoparticles.

[0079] Comparative Example 1

[0080] The only difference between Comparative Example 1 and Example 1 is that no functional materials are added to the second coating liquid.

[0081] Comparative Example 2

[0082] The only difference between Comparative Example 2 and Example 1 is that the functional material in the second coating liquid is replaced with pure titanium dioxide nanoparticles.

[0083] Comparative Example 3

[0084] The only difference between Comparative Example 3 and Example 1 is that, by weight, 3 parts of small-diameter PMMA polymer particles with a particle size of 8 μm, 1.5 parts of large-diameter PU polymer particles with a particle size of 25 μm, 40 parts of acrylic resin adhesive, 4 parts of isocyanate, 0.7 parts of lithium bis(trifluoromethanesulfonyl)imide, and 0.3 parts of functional material are dispersed in 50.5 parts of ethyl acetate, ultrasonically dispersed for 1 hour, and stirred evenly to obtain a coating liquid. The obtained coating liquid is then coated on the surface of a PET reflective substrate and cured in an oven at 110°C for 2 minutes to obtain the final coating.

[0085] Comparative Example 4

[0086] The only difference between Comparative Example 4 and Example 1 is that, when preparing the first coating liquid, the amount of small-diameter PMMA polymer particles with a particle size of 8 μm is 4.5 parts and the amount of large-diameter PU polymer particles with a particle size of 25 μm is 0 parts.

[0087] Comparative Example 5

[0088] The only difference between Comparative Example 5 and Example 1 is that, when preparing the first coating liquid, the amount of small-diameter PMMA polymer particles with a particle size of 8 μm is 0 parts, and the amount of large-diameter PU polymer particles with a particle size of 25 μm is 4.5 parts.

[0089] The performance of the layered coating type reflective films of the examples and comparative examples was tested. The test methods are as follows, and the results are shown in Table 1.

[0090] Brightness test: The reflective film was placed in the side-lit backlight module and the brightness was tested using a BM-7A luminance meter.

[0091] Top white value measurement: Assemble the reflective film into the side-lit backlight module, press the backlight module with a push-pull force gauge, and record the pressure reading when the white spot is about to appear but has not yet appeared. The data obtained is the top white value.

[0092] Table 1

[0093]

[0094] Based on the results of Example 1 and Comparative Examples 1-3, it can be seen that coating polymer particles and functional materials of mixed particle sizes onto the reflective film separately by a layered coating method can maximize the excellent performance of polymer particles and functional materials compared to directly adding them to the coating liquid, thereby improving the reflective film's anti-adsorption effect, optical brightness, tensile strength, heat resistance, etc.

[0095] The results from Example 1, Example 2, Example 3, Comparative Example 4, and Comparative Example 5, and Figures 1-3 It is known that the mass ratio of small-diameter polymer particles to large-diameter polymer particles affects the luminance and top white value of the high-brightness layered coating reflective film. In Example 1, the mass ratio of small-diameter polymer particles to large-diameter polymer particles is optimal. In Examples 2 and 5, increasing the proportion of large-diameter polymer particles results in a rougher film surface, making the resulting reflective film more prone to scratching the light guide plate (e.g., during scratch tests). Figure 3 Furthermore, the gaps between large particles cannot be effectively filled by small particles, resulting in a slight decrease in the average luminance of the reflective film. In Examples 3 and 4, the proportion of small-diameter polymer particles increased, while the proportion of large particles in the coating decreased, leading to a worse anti-whitening effect of the reflective film.

[0096] As can be seen from the results of Examples 1, 4, and 5, if the amount of functional material added to the coating is too small, the brightness improvement effect of the resulting reflective film is weak. If the amount of functional material added to the coating is too large, the light absorption of CNTs will cause the brightness of the reflective film to decrease, and too much functional material will affect the flatness of the film surface.

[0097] The results of Examples 1 and 6 show that single-walled carbon nanotubes have a very large specific surface area. In the subsequent synthesis of functional materials, the use of magnetic stirring alone caused the single-walled carbon nanotubes to re-agglomerate into bundles, which affected the growth of titanium dioxide nanoparticles. In contrast, the multi-walled carbon nanotubes used are relatively less likely to form dense agglomerates and are easier to disperse than single-walled carbon nanotubes. They are suitable for the synthesis of functional materials, and multi-walled carbon nanotubes have a higher cost-performance ratio and are more suitable for industrial production.

[0098] As can be seen from the results of Examples 1 and 7 and 8, carbon nanotubes, as excellent conductive materials, can reduce the surface resistivity of the reflective film when added to the reflective film coating, which is beneficial for the cutting and assembly of the product at the back end.

[0099] As shown in the results of Examples 1, 9, and 10, titanium dioxide nanoparticles have a higher refractive index than zinc oxide nanoparticles and zirconium oxide nanoparticles, which can enhance interface reflection and light scattering, thereby improving the brightness of the reflective film. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0100] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A layered coating type reflective film, characterized in that, The material includes a reflective substrate and a first coating and a second coating sequentially stacked on the reflective substrate. The first coating includes at least polymer particles of mixed particle sizes, and the second coating includes at least a functional material. The functional material includes a one-dimensional tubular carrier and metal oxide nanoparticles with a refractive index of 1.6 or higher loaded on the one-dimensional tubular carrier. The content of the functional material on the side of the second coating away from the first coating is higher than the content on the side closer to the first coating.

2. The layered coating type reflective film according to claim 1, characterized in that, By mass fraction, the first coating liquid used in the first coating layer comprises 3wt% to 6wt% polymer particles, 38wt% to 42wt% adhesive, 3.8wt% to 4.2wt% curing agent, 0.5wt% to 1wt% antistatic agent, and the balance being solvent; And / or, the thickness of the first coating is 20μm~40μm.

3. The layered coating type reflective film according to claim 1 or claim 2, characterized in that, The polymer particles include small-diameter polymer particles with a particle size of 3μm to 10μm and large-diameter polymer particles with a particle size of 20μm to 34μm, and the mass ratio of the small-diameter polymer particles to the large-diameter polymer particles is 1:1 to 3:

1.

4. The layered coating type reflective film according to claim 2, characterized in that, The polymer particles in the first coating liquid are selected from at least one of polyethylene terephthalate particles, polymethyl methacrylate particles, polybutyl methacrylate particles, polyamide particles, and polyurethane particles; And / or, the adhesive in the first coating liquid is selected from at least one of acrylic resin adhesive, polycarbonate resin adhesive, polyurethane resin adhesive, and polyimide resin adhesive; And / or, the curing agent in the first coating liquid is selected from at least one of isocyanate, epoxy resin, methylphenol resin, and dicyandiamide; And / or, the antistatic agent in the first coating liquid is selected from lithium trifluoromethanesulfonate; And / or, the solvent in the first coating solution is selected from at least one of ethyl acetate, butyl acetate, and acetone.

5. The layered coating type reflective film according to claim 1, characterized in that, The one-dimensional tubular support is selected from at least one of carbon nanotube support, boron nitride nanotube support, and molybdenum disulfide nanotube support. And / or, the metal oxide nanoparticles are selected from at least one of titanium dioxide nanoparticles, zirconium oxide nanoparticles, and zinc oxide nanoparticles.

6. The layered coating type reflective film according to claim 1, characterized in that, The second coating is a UV coating; And / or, the thickness of the second coating is 2μm~6μm.

7. The layered coating type reflective film according to claim 6, characterized in that, By mass fraction, the second coating liquid used in the second coating layer comprises 0.1wt% to 0.5wt% of functional materials, 48wt% to 52wt% of oligomers, 4.5wt% to 5.7wt% of photoinitiator, and 42wt% to 46wt% of UV diluent.

8. The layered coating type reflective film according to claim 7, characterized in that, The oligomer in the second coating liquid is selected from at least one of polyacrylate oligomers, polyether acrylate oligomers, polysiloxane acrylate oligomers, and polyamino acrylate oligomers; And / or, the photoinitiator in the second coating liquid is selected from at least one of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-methylphenylpropane-1-one, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide and xylene ketone; And / or, the UV diluent in the second coating liquid is selected from at least one of methyl acrylate, ethyl acrylate, butyl acrylate and isobornyl acrylate.

9. The layered coating type reflective film according to claim 1, characterized in that, The reflective substrate is selected from at least one of polyester film and polypropylene film; And / or, the thickness of the reflective substrate is 50μm~150μm.

10. A side-lit backlight module, characterized in that, Includes the layered coating type reflective film as described in any one of claims 1 to 9.

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