Quantum dot optical film for LCD display and preparation method thereof

Abstract

The invention discloses a quantum dot optical film for LCD display and a preparation method of the quantum dot optical film. The quantum dot optical film structurally comprises an optical base film, a glue layer, a nanoscale inorganic SiO2 coating, a quantum dot prism structure layer, an organic siloxane coating and an optical base film from bottom to top. The optical film has the functions of brightening, enhancing the color gamut and blocking water and oxygen, the functions of different optical films in an existing LCD backlight module are integrated, and the backlight module is light; an optical-grade base film is used for replacing a commercial barrier film, and a physical barrier and chemical barrier combined mode is adopted, so that the water and oxygen barrier performance is improved, and meanwhile, the use of the commercial barrier film is reduced; the prism structure is integrated into the quantum dot optical film, so that the brightness enhancement effect is achieved, the production and assembly cost is reduced, multiple coating operations are avoided, and the process yield is improved; the brightness enhancement function of the prism is integrated into the quantum dot optical film, the water and oxygen barrier performance is enhanced, the use of commercial barrier films is reduced, the production and assembly cost is reduced, and the light weight effect of the backlight module is achieved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor display technologies, and in particular, to a quantum dot optical film for LCD display and a preparation method thereof. Background Art

[0002] Quantum dots are an important type of fluorescent nanomaterial with a particle size of about 1 - 20 nm. Due to the size - dependent effect and quantum confinement effect of quantum dots themselves, they have characteristics such as a broad excitation spectrum, a narrow emission spectrum, a narrow full - width at half - maximum, and a high fluorescence quantum yield, and are widely used in many fields including biological analysis, optoelectronic devices (solar cells, light - emitting diodes), lighting, information display, etc.

[0003] In recent years, the most successful commercial application of quantum dots is to integrate quantum dots into an optical film for use in the field of LCD backlight display. Currently, most commercial quantum dot optical films are composed of three structures, which are, from top to bottom, a barrier film, a quantum dot glue layer, and a barrier film. Since the specific surface area of quantum dots is large, water vapor and oxygen in the air are likely to damage the surface of quantum dots, resulting in fluorescence quenching of quantum dots and affecting product performance. The use of a barrier film can effectively inhibit the occurrence rate of quantum dot quenching. The barrier film generally consists of a PET substrate with a back - coating and a barrier layer, and mainly blocks external water vapor and oxygen through this physical barrier form. However, the use of this laminated barrier film will cause creases during production or assembly, resulting in picture quality problems such as "black lines" and "dark spots". In addition, the basic architecture of current displays using blue light and quantum dot technology usually includes: a common GaN blue - light array, a quantum dot film (containing red and green quantum dots), a brightness - enhancement film, a diffusion film, a liquid - crystal display screen, etc. However, the above - mentioned architecture consists of multiple independent optical film sheets, which is not conducive to the thin - type design of the overall backlight structure.

[0004] Chinese Patent CN113561517A discloses a manufacturing process and equipment for a high - definition thin brightness - enhancement polyester - based film. Applied to LCD displays, it mentions that the brightness - enhancement film is also called a prism film. In the existing polyester - based film coating, the leveling agent is polydimethylsiloxane, and the optical glue is cured into a pre - designed optical micro - prism structure coating. By using the light - converging effect of the micro - prism structure, the scattered light is concentrated towards the front to improve the overall brightness and uniformity of the LCD panel, which is a new type of high - performance optical material. However, considering that the patent of CN113561517A protects the manufacturing process and equipment of an optical film with a brightness - enhancement function, in the claims of this invention, there is no structure for color conversion or gamut improvement, and it does not contain quantum dots at the nanoscale level, so the existing technology has some deficiencies.

[0005] Chinese Patent CN106680915A discloses a composite brightness enhancement film applied to a backlight module and a backlight module. This application discloses that the backlight module is an important component for LCD display functions. The traditional brightness enhancement film includes a substrate and a prism structure layer. The light condensing layer is made of an ultraviolet curable resin glue, and the organic diffusion particles are selected from silicone resins. However, considering that the invention protects a composite brightness enhancement film composed of a light condensing layer, a transparent substrate layer, and a diffusion layer, there is no structural function for color conversion or gamut improvement in the claims, nor does it contain defects such as quantum dots at the nanoscale level, so the prior art seems to be slightly insufficient.

[0006] Chinese Patent CN105301826A, a brightness enhancement film applied to a large-size display, discloses that since LCDs cannot emit light actively and need to rely on a backlight module to achieve the display function, the brightness enhancement film mainly utilizes the total reflection of light by the micro-prism structure. The brightness enhancement film uses a lamination technique to prepare a thicker base film from two thinner base films (diffusion film and transparent substrate film), and uses UV glue on one side to prepare a microstructure. The light condensing layer includes a number of micro-prism structures, and the cross-section of the micro-prism structure is an isosceles triangle. The micro-prism structure of the light condensing layer is made of an ultraviolet curable resin glue, and the organic diffusion particles are selected from silicone resins. Compared with this application, the distinguishing technical features of this invention are: this invention protects a composite brightness enhancement film composed of a transparent substrate layer, a light condensing layer composed of micro-prisms, and a diffusion layer. Considering that this invention does not have structural functions such as color conversion or gamut improvement and other defects, the prior art seems to be slightly insufficient.

[0007] Currently, quantum dot liquid crystal display devices are widely used in the industry. Its architecture sequentially includes a blue backlight source, a diffusion plate, a quantum dot film, a brightness enhancement film, a diffusion film, a liquid crystal display screen, etc. that are stacked on each other. Among them, the quantum dot film is composed of a barrier film, a quantum dot glue layer, and a barrier film. However, the quantum dot film structure still has the following defects: 1. The use of the laminated barrier film will cause creases during production or assembly, resulting in picture quality problems such as "black lines" and "dark spots". 2. The barrier film generally relies on imports, resulting in an increase in the production cost of the optical film. The overall backlight architecture is composed of stacked independent optical film sheets. When assembling the product, scratches and abrasions will occur between adjacent optical film sheets, affecting their brightness. In addition, this architecture is not conducive to product lightweighting. Summary of the Invention

[0008] Technical problems to be solved:

[0009] The object of the present invention is to overcome the technical problems existing in the prior art, such as the large specific surface area of quantum dots, the water vapor and oxygen in the air are likely to damage the surface of quantum dots, resulting in fluorescence quenching of quantum dots and affecting the product performance; it is composed of multiple independent optical films, which is not conducive to the thin design of the overall backlight structure, the use of the laminated barrier film will cause creases in production or assembly, resulting in "black lines" and "dark spots", and scratches and abrasions will occur between adjacent optical films. The present application provides a quantum dot optical film for LCD display and its preparation method.

[0010] Technical solution:

[0011] To achieve the above object, the present application is realized through the following technical solutions:

[0012] A preparation method of a quantum dot optical film for LCD display, comprising the following steps:

[0013] The first step is to prepare the inner coating glue: place the polyurethane matrix resin in an environment of 40-60 °C and heat it for 30-60 min, then weigh 5-30 parts of the polyurethane matrix resin, 0.01-0.05 parts of the thermosetting resin containing unsaturated bonds, and 0.01-0.1 parts of the silane reagent according to the mass ratio, add them to 100 parts of the diluent solvent, and mechanically stir at 200-1000 rpm for 10-30 min until completely dissolved;

[0014] The second step is to introduce an inner coating containing organosiloxane on the optical grade base film: coat the inner coating glue prepared in the first step on the flat optical grade base film by roll-to-roll coating, knife coating, dipping or spraying methods to form an inner coating with a thickness of 0.5-3 μm, that is, an organosiloxane coating;

[0015] The third step is to prepare the quantum dot glue: according to the mass ratio of red quantum dot nanoparticles: green quantum dot nanoparticles: scattering particles:

[0016] matrix resin: initiator = (1-5):(1-4):(10-20):(1-5):(0.01-0.05); mechanically stir the red quantum dot nanoparticles, green quantum dot nanoparticles, scattering particles, matrix resin and initiator at room temperature for 30-120 min until evenly mixed;

[0017] The fourth step is to prepare the prism glue: according to the mass ratio of the UV acrylate monomer with monofunctional or bifunctional groups: curing agent

[0018] = 100:0.1-0.5; take the UV acrylate monomer with monofunctional or bifunctional groups and the curing agent and stir at 40 °C for 2-4 h until evenly mixed;

[0019] Step 5: On the optically clear substrate coated with the inner coating prepared in Step 2, introduce a quantum dot prism structure layer composed of a quantum dot glue and a prism glue: Take the quantum dot glue prepared in Step 3 and the prism glue prepared in Step 4 according to the mass ratio of quantum dot glue:prism glue = (1 - 10):(20 - 50), and stir at 50 - 200 rpm for 60 - 240

[0020] min in a heating environment of 40°C to 50°C to obtain a microstructured glue of quantum dots. The microstructured glue of quantum dots is applied by roll-to-roll coating. Select a copper-plated roller or a soft film with a microstructure, and transfer it to the flat optically clear substrate with an organosiloxane inner coating prepared in Step 2 by UV curing to form a microprism or microlens structure film layer with a complete, uniform, and continuous distribution. Then, pass through a high-temperature oven at 60 - 110°C to remove the remaining diluent solvent on the film to obtain a quantum dot prism structure layer;

[0021] Step 6: Evaporate or sputter a nano-scale inorganic SiO2 coating on the surface of the quantum dot prism structure layer: Use a vacuum evaporation process to evaporate or sputter a 2 - 6 nm inorganic SiO2 coating on the quantum dot prism structure layer. Heat the coating material to evaporation by electron beam heating, resistance heating, radio frequency induction heating, arc heating, or laser heating. The evaporated coating material condenses on the surface of the quantum dot prism structure layer to form a uniform and dense nano-scale inorganic SiO2 coating;

[0022] Step 7: Prepare a blank filling UV acrylate glue layer, i.e., a glue layer: Take a monofunctional acrylate, a difunctional acrylate, and a trifunctional acrylate according to the mass ratio of monofunctional acrylate:difunctional acrylate:trifunctional acrylate = 3 - 5:2 - 3:1. Mix them by mechanical stirring at room temperature at a rotation speed of 200 - 500 rpm for 30 - 60 min to obtain the glue layer;

[0023] Step 8: Based on the roll-to-roll coating line, under the irradiation of a 365 nm LED lamp, select an energy of 50 - 200 mJ / cm 2 , with a coating speed of 5 - 15 m / min, and bond the nano-scale inorganic SiO2 coating to the optically clear substrate through the glue layer to obtain a quantum dot optical film for LCD display.

[0024] Preferably, in the first step, the main resin component of the inner coating glue is a thermosetting resin containing unsaturated bonds. The thermosetting resin containing unsaturated bonds is one or more of epoxy resin, polyurethane, and acrylic resin; the diluent solvent is ethyl acetate and / or cyclopropanone; the silane reagent is a silane with an unsaturated double bond or a silane containing an epoxy group, specifically: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, mercaptopropylsilane, 3-mercaptopropyltrimethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(β-aminoethyl-γ-aminopropyl)trimethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, diethylenetriaminepropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, n-butylaminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine, 3-(phenylamino)propyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, propyltrimethoxysilane, one or more of them; the refractive index of the inner coating glue is 1.48 - 1.51, and the viscosity is 100 to 300 cps.

[0025] Preferably, in the second step, the optical grade base film is one or more of polyethylene terephthalate PET, polyethylene naphthalate PEN, polycarbonate PC, polymethyl methacrylate PMMA, polyethylene PE, and polyvinylidene fluoride PVDF transparent base films. The thickness of the optical grade base film is 12 - 150 μm. The surface of the optical grade base film is flat, without MD lines and TD lines, and the light transmittance is above 90%. The water and oxygen barrier rate of the optical grade PET base film is 2 - 6 g / (m 2 ·day).

[0026] Preferably, in the third step, the scattering particles are one or more of silica, titanium dioxide, zinc oxide, and organosilicon, and the particle size of the scattering particles is 100-2000 nm; the red quantum dot nanoparticles and the green quantum dot nanoparticles are oil-soluble quantum dots with organic ligands distributed on the surface, and the organic ligands are one or more of oleic acid, oleylamine, and long-chain organophosphorus compounds. The long-chain organophosphorus compounds are selected from tetradecylphosphine and / or octadecylphosphine; the wavelength range of the red quantum dot nanoparticles is 600-640 nm, and the wavelength range of the green quantum dot nanoparticles is 510-540 nm; according to the mass ratio, the total mass of the red quantum dot nanoparticles and the green quantum dot nanoparticles: the thermosetting resin containing unsaturated bonds = 1:150-200; the addition amount of the scattering particles accounts for 0.01-0.03% of the total mass of the red quantum dot nanoparticles, the green quantum dot nanoparticles, and the thermosetting resin containing unsaturated bonds; the matrix resin is one or more of UV acrylate type, epoxy resin, and polyurethane; the inorganic crystal composition of the red quantum dot nanoparticles and the green quantum dot nanoparticles is one or more of CdSe, CdS, CdZnS, ZnSe, and InP, and organic ligands are distributed on the surface.

[0027] Preferably, in the fourth step, the refractive index of the prism glue is 1.48-1.51, and the viscosity is 50-300 cps; the monofunctional UV acrylate monomer is one or more of caprolactone acrylate, 2-phenoxyethyl acrylate, o-phenylphenoxyethyl acrylate, and isobornyl acrylate; the difunctional UV acrylate monomer is one or more of dipropylene glycol diacrylate, tripropylene glycol diacrylate, and neopentyl glycol diacrylate; the curing agent is TOP or TOP-L.

[0028] Preferably, the fifth-step microprism or microlens structure is formed by curing acrylate adhesives with different refractive indices. Through the microprism or microlens structure, light in the horizontal or vertical direction can be converged and emitted along the direction of the LCD screen, efficiently collecting the light of the backlight source. There are two implementation methods for the microprism or microlens. One is realized by transfer printing with a copper-plated roller engraved with microstructures, and the other is realized by flipping a soft film with microstructures. For the copper-plated roller with microstructures, a tool is used to precisely engrave the surface of the copper-plated roller to control and realize various parameters of the microprisms, including: the apex angle of the microprism, the pitch of the microprism, and the bottom side length of the prism. Finally, the microstructures on the copper-plated roller are transferred onto a flat optical-grade base film. For the soft film, first, a copper-plated roller with microstructures is used for transfer printing to prepare a soft film with microstructures, and these master films serve as the soft films. Then, through reverse transfer printing of the soft film, microstructures are obtained on a flat optical-grade base film, and the microprism or microlens structure formed by curing the microstructured glue of quantum dots. Different microstructures are realized by transfer printing with a copper-plated roller engraved with microstructures or by flipping a soft film with microstructures. The pitch of the microprism structure is 20 - 70 μm, the height of the prism is 10 - 35 μm, and the included angle of the prism apex angle is 70 - 120°. The microlens is a hemispherical structure formed by a resin adhesive, and its diameter is 20 - 50 μm.

[0029] Preferably, in the sixth step, the coating material is a high-purity oxide with a high melting point and a low vapor pressure. Silicon dioxide can be replaced by one or several of titanium dioxide, zinc oxide, and aluminum oxide. The thickness of the nano-scale inorganic SiO2 coating is 2 - 6 nm. With a nano-scale thickness, SiO2 itself has a dense structure, which can prevent water and oxygen molecules in the environment from entering the prism structure, improving the stability of the prism structure and ensuring the stability of the quantum dots in the prism.

[0030] Preferably, the mono-functional acrylate is one or several of methyl acrylate, ethyl acrylate, and isopropyl acrylate, the di-functional acrylate is one or several of dipropylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,6-hexanediol diacrylate, and the tri-functional acrylate is polyurethane acrylate and / or trimethylolpropane triacrylate. The thickness of the glue layer is 20 - 50 μm, and the refractive index is 1.51 - 1.53.

[0031] This application also discloses a quantum dot optical film for LCD display prepared by any of the above preparation methods. The structure of the quantum dot optical film for LCD display from bottom to top is respectively: an optical-grade base film, a glue layer, a nano-scale inorganic SiO2 coating, a quantum dot prism structure layer, an organosiloxane inner coating, and an optical-grade base film.

[0032] Preferably, the refractive index of the quantum dot prism structure layer is 1.51 - 1.53.

[0033] Beneficial effects:

[0034] The present application provides a quantum dot optical film for LCD display and a preparation method thereof, having the following beneficial effects:

[0035] 1. The optical film has functions such as brightness enhancement, color gamut enhancement, high water and oxygen resistance, etc. For the quantum dot optical film of the present application, the stability of quantum dots can be improved. Based on the fact that quantum dots are prone to quenching, first, a glue system composed of a matrix resin and quantum dots is used to encapsulate the quantum dots; secondly, on the prepared quantum dot microstructure layer, a vacuum evaporation process is adopted to introduce a nano-scale inorganic SiO2 coating to physically block water vapor and oxygen, further protecting the glue system of the quantum dots and reducing the quenching of quantum dots, thereby improving the stability of quantum dots;

[0036] 2. The product of the present application adopts an internal "water and oxygen barrier" structure combining physical barrier and chemical barrier. While improving the water and oxygen barrier performance, it reduces the use of commercial barrier films and lowers the production cost. For the quantum dot optical film of the present application, the peel strength between film layers can be improved. In commercial quantum dot optical films, a barrier film is used as the base material, and a high-viscosity photocurable adhesive is selected and bonded through high-temperature curing; the bonding strength (i.e., peel strength) between film layers mainly depends on the viscosity of the photocurable adhesive and the regulation of UV energy; the silane reagent adopted in the present application has two functional groups of organic group affinity and inorganic group affinity in its molecule, which can serve as a "molecular bridge" connecting organic molecules and inorganic molecules, and finally form a connection layer of inorganic phase (nano-scale inorganic SiO2)-silane reagent-organic phase (photocurable adhesive); therefore, in the quantum dot optical film of the present application, in addition to using a high-viscosity photocurable adhesive to increase the peel strength, the organosiloxane coating coated on the PET substrate will undergo a hydrolysis reaction when encountering water and oxygen in the outside world, and the hydrolysis products generated will continue to undergo a condensation reaction with the inorganic SiO2 layer, finally forming a dense and uniform network structure, achieving the effect of chemically blocking water and oxygen while significantly improving the bonding strength and durability between film layers;

[0037] 3. Integrating the brightness enhancement function of microprisms or microlenses into the quantum dot optical film can also reduce the production and assembly costs, avoid multiple coating operations, improve the process yield, reduce the thickness of the overall module, simplify the installation difficulty of the module, and reduce the production cost. By adding quantum dots to the prism glue layer, the optical film simultaneously has the characteristics of brightness enhancement of the prism and high color gamut of quantum dots, which can replace the existing form of superposition of quantum dot films and prism films, or microlens films, reducing the thickness of the overall module, simplifying the installation difficulty of the module, and reducing the production cost under the premise of ensuring the optical performance of the whole machine;

[0038] 4. The novel quantum dot optical film proposed by the present invention does not require a commercial barrier film. Quantum dots have the characteristics of a broad absorption spectrum, a narrow emission spectrum, high light stability, and adjustable color. However, quantum dots will undergo fluorescence quenching after contacting water vapor or oxygen in the air, affecting their performance. To solve this problem, currently, commercial quantum dot optical films usually use a barrier film as the substrate, encapsulate quantum dots with resin, and coat them. The barrier film is obtained by coating or laminating a barrier layer onto a PET substrate. The commercial barrier film (relative to the PET base film) has a high cost, and during the production and assembly of quantum dot optical films, problems such as "black lines" and "dark spots" are likely to occur in the picture. The quantum dot optical film of this application has an internal "water and oxygen barrier" structure. While ensuring the performance of quantum dots, it can not only reduce the defective rate of the picture but also reduce the use of commercial barrier films and lower the production cost;

[0039] 5. The products of this application have a wide range of application scenarios, such as LCD displays, such as TVs, desktop computers, in-vehicle displays, laptops, etc. Description of the Drawings

[0040] Figure 1 It is a schematic diagram of introducing a silicone oxide coating on an optical-grade PET base film in the second step of Example 1 of this application;

[0041] Figure 2 It is a schematic diagram of introducing a quantum dot prism structure layer composed of micro prism glue and quantum dot glue on the silicone oxide coating in the fifth step of Example 1 of this application;

[0042] Figure 3 It is a schematic diagram of evaporating or sputtering a nanoscale inorganic SiO2 coating on the surface of the quantum dot micro prism structure layer in the sixth step of Example 1 of this application;

[0043] Figure 4 It is a schematic diagram of a chemical reaction occurring between the silicone oxide layer and the nanoscale inorganic layer in an air environment in the sixth step of Example 1 of this application;

[0044] Figure 5 It is a schematic diagram of manufacturing a quantum dot optical film for LCD display by roll-to-roll coating and laminating in the eighth step of Example 1 of this application;

[0045] Figure 6 It is a schematic diagram of the structure of the quantum dot optical film for LCD display of this application;

[0046] Figure 7 It is a backlight application architecture diagram of the quantum dot optical film for LCD display of this application.

[0047] Description of the reference numerals: 1. Optical-grade base film; 2. Glue layer; 3. Nanoscale inorganic SiO2 coating; 4. Quantum dot prism structure layer; 5. Silicone oxide inner coating. Detailed implementation mode

[0048] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made. These all belong to the protection scope of the present invention.

[0049] Embodiment 1

[0050] A preparation method of a quantum dot optical film for LCD display includes the following steps:

[0051] The first step is to prepare the inner coating glue: Place the polyurethane matrix resin in an environment of 40°C and heat it for 30 minutes. Then, weigh 5 parts of the polyurethane matrix resin, 0.01 part of the thermosetting resin containing unsaturated bonds, and 0.01 part of the silane reagent according to the mass ratio, and add them to 100 parts of the diluent solvent. Stir mechanically at 200 rpm for 10 minutes until completely dissolved:

[0052] The second step is to introduce an organosiloxane coating on the optical-grade PET base film: Coating the inner coating glue prepared in the first step on the flat base film by roll-to-roll coating, knife coating, dipping or spraying methods to form an inner coating with a thickness of 0.5 μm, that is, an organosiloxane coating;

[0053] The third step is to prepare the quantum dot glue: According to the mass ratio of red quantum dot nanoparticles: green quantum dot nanoparticles: scattering particles: matrix resin: initiator = 1:1:10:1:0.01; Mechanically stir the red quantum dot nanoparticles, green quantum dot nanoparticles, scattering particles, matrix resin and initiator at room temperature for 30 minutes, and the stirring speed is 100 rpm until evenly mixed;

[0054] The fourth step is to prepare the prism glue: According to the mass ratio of UV acrylate monomers with monofunctional or bifunctional groups: curing agent = 100:0.1; Take the UV acrylate monomers with monofunctional or bifunctional groups and the curing agent and stir at 40°C for 2 hours until evenly mixed;

[0055] Step 5: On the base film coated with the inner coating prepared in Step 2, introduce a quantum dot microstructure layer composed of a prism glue and a quantum dot glue: Take the quantum dot glue prepared in Step 3 and the prism glue prepared in Step 4 according to the mass ratio of quantum dot glue:prism glue = 1:20, stir at 50 rpm for 60 min in a heating environment at 40°C to obtain the microstructure glue of quantum dots. The microstructure glue of quantum dots is coated in a roll-to-roll manner, and a rigid roller or a soft film with a microstructure is selected, and transferred to the flat base film with a silicone oxide inner coating prepared in Step 2 through UV curing to form a micro prism or micro lens structure film layer with a complete, uniform and continuous distribution. Then, pass through a high-temperature oven at 60°C to remove the remaining diluent solvent on the film to obtain a quantum dot prism structure layer;

[0056] Step 6: Evaporate or sputter a nanoscale inorganic SiO2 coating on the surface of the quantum dot prism structure layer: Use a vacuum evaporation process to evaporate or sputter a 2-nm inorganic SiO2 coating on the quantum dot prism structure layer, and heat the coating material to evaporation by electron beam heating, resistance heating, radio frequency induction heating, arc heating or laser heating methods. The evaporated coating material condenses on the surface of the quantum dot prism structure layer to form a uniform and dense nanoscale inorganic SiO2 coating;

[0057] Step 7: Configure a blank filling UV acrylate glue layer, i.e., a glue layer: Take monofunctional acrylate:bifunctional acrylate:trifunctional acrylate according to the mass ratio of 3 - 5:2 - 3:1; Take monofunctional, bifunctional and trifunctional acrylates, and mechanically stir and mix at room temperature at a rotation speed of 200 rpm for 30 min to obtain the glue layer;

[0058] Step 8: Based on the roll-to-roll coating line, under the irradiation of a 365-nm LED lamp, with an energy of 50 mJ / cm 2 , a coating speed of 5 m / min, and bond the nanoscale inorganic SiO2 coating and the optical grade base film through the glue layer to obtain a quantum dot optical film for LCD display.

[0059] In the first step, the main resin component of the inner coating glue is a thermosetting resin containing unsaturated bonds. The thermosetting resin containing unsaturated bonds is one or more of epoxy resin, polyurethane, and acrylic resin. The diluent solvent is ethyl acetate and / or cyclohexanone. The silane reagent is a silane with an unsaturated double bond or a silane containing an epoxy group, specifically: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, mercaptopropylsilane, 3-mercaptopropyltrimethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(β-aminoethyl-γ-aminopropyl)trimethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, diethylenetriaminepropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, n-butylaminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine, 3-(phenylamino)propyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, propyltrimethoxysilane; the refractive index of the inner coating glue is 1.48 - 1.51, and the viscosity is 100 to 300 cps..

[0060] In the second step, the optical-grade base film is a transparent base film of polyethylene terephthalate PET, polyethylene naphthalate PEN, polycarbonate PC, polymethyl methacrylate PMMA, polyethylene PE, or polyvinylidene fluoride PVDF. The thickness of the optical-grade base film is 12 - 150 μm. The surface of the optical-grade base film is flat, without MD lines and TD lines, and the light transmittance is above 90%. The water and oxygen barrier rate of the optical-grade PET base film is 2 - 6 g / (m 2 ·day). The physical barrier performance against water and oxygen is lower than that of commercial barrier films. When used in combination with the inner coating containing a silane reagent, it produces a synergistic effect, increasing the chemical barrier of the silane reagent hydrolysis reaction on the basis of the PET barrier performance and enhancing the water and oxygen barrier performance.

[0061] In the third step, the scattering particles are one or more of silicon dioxide, titanium dioxide, zinc oxide, and organosilicon, and the particle size of the scattering particles is 100-2000 nm; the red quantum dot nanoparticles and the green quantum dot nanoparticles are oil-soluble quantum dots with organic ligands distributed on the surface. The organic ligands are oleic acid and / or oleylamine / or long-chain organophosphorus compounds, and the long-chain organophosphorus compounds are selected from tetradecylphosphine and / or octadecylphosphine; the wavelength range of the red quantum dot nanoparticles is 600-640 nm, and the wavelength range of the green quantum dot nanoparticles is 510-540 nm; according to the mass ratio, the total mass of the red quantum dot nanoparticles and the green quantum dot nanoparticles: the thermosetting resin containing unsaturated bonds = 1:150-200; the addition amount of the scattering particles accounts for 0.01-0.03% of the total mass of the red quantum dot nanoparticles, the green quantum dot nanoparticles, and the thermosetting resin containing unsaturated bonds; the matrix resin is one or more of UV acrylate type, epoxy resin, and polyurethane; the inorganic crystal compositions of the red quantum dot nanoparticles and the green quantum dot nanoparticles are one or more of CdSe, CdS, CdZnS, ZnSe, and InP, and organic ligands are distributed on the surface.

[0062] In the fourth step, the refractive index of the prism glue is 1.48-1.51, and the viscosity is 50-300 cps; the monofunctional monomers are one or more of caprolactone acrylate, 2-phenoxyethyl acrylate, o-phenylphenoxyethyl acrylate, and isobornyl acrylate; the difunctional monomers are one or more of dipropylene glycol diacrylate, tripropylene glycol diacrylate, and neopentyl glycol diacrylate; the curing agent is TOP or TOP-L.

[0063] In the fifth step, the microstructure in the quantum dot microstructure glue is a microprism or microlens structure. The microprism or microlens structure is formed by curing acrylate glues with different refractive indices. Through the microprism or microlens structure, light in the horizontal or vertical direction can be converged and emitted along the direction of the LCD screen, efficiently collecting the light of the backlight source. Through the transfer method, the microstructure is transferred to the target base film. There are two ways to achieve the microstructure: one is through transfer printing with a copper-plated roller engraved with the microstructure, and the other is through flipping a soft film with the microstructure. For the copper-plated roller with the microstructure, a tool is used to precisely engrave the surface of the copper-plated roller to control and achieve various parameters of the microprisms, including: the apex angle of the microprism, the pitch of the prism, and the base length of the prism. Finally, the microstructure on the copper-plated roller is transferred onto the target base film. For the soft film, first, a copper-plated roller with the microstructure can be used for transfer printing to prepare a soft film with the microstructure, and these master films serve as the soft films. Then, through reverse transfer printing of the soft film, the microstructure is obtained on the target base film. The microprism or microlens structure formed by curing the quantum dot microstructure glue, different microstructures are achieved through transfer printing with a copper-plated roller engraved with the microstructure or through flipping a soft film with the microstructure. The pitch of the microprism structure, the base length is 50 μm, the height of the prism is 25 μm, and the included angle of the prism apex angle is 90°. The microlens is a hemispherical structure formed by a resin glue, with a diameter of 20 - 50 μm.

[0064] In the sixth step, the evaporation material is a high-purity oxide with a high melting point and low vapor pressure, specifically one or several of silicon dioxide, titanium dioxide, zinc oxide, and aluminum oxide. The thickness of the nano-scale inorganic SiO2 coating is 2 nm. With a nano-scale thickness, SiO2 itself has a dense structure, which can prevent molecules such as moisture and oxygen in the environment from entering the prism structure, improving the stability of the prism structure and ensuring the stability of the quantum dots in the prism.

[0065] The monofunctional acrylate is one or several of methyl acrylate, ethyl acrylate, and isopropyl acrylate. The difunctional acrylate is one or several of dipropylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,6-hexanediol diacrylate. The trifunctional acrylate is polyurethane acrylate and / or trimethylolpropane triacrylate. The thickness of the glue layer is 20 - 50 μm, and the refractive index is 1.51 - 1.53.

[0066] The structure of the quantum dot optical film for LCD display in this application from bottom to top is as follows: optical grade base film 1, glue layer 2, nano-scale inorganic SiO2 coating 3, quantum dot prism structure layer 4, organosiloxane inner coating 5, and optical grade base film. The structure can be determined and analyzed by preparing a cross-section sample of the sample and then using a 3D optical microscope or a cross-sectional scanning electron microscope (cross-sectional SEM). The composition of the substances in the film and the added micro-nano particles can be analyzed by an energy dispersive spectrometer (EDS). The refractive index of the prism structure layer is 1.51 - 1.53.

[0067] Scanning transmission electron microscope combined with energy dispersive spectrometer (STEM-EDS), this device can determine the cross-sectional morphology of the film, the morphology and elemental composition of the quantum dot glue layer.

[0068] The quantum dot optical film prepared according to Example 1 is used in the LCD backlight module. Figure 7 This is the backlight application architecture diagram of the quantum dot optical film for LCD display in this application. The basic structure from bottom to top is: blue backlight source, quantum dot optical film, TFT-LCD panel, etc.

[0069] Example 2

[0070] A preparation method of a quantum dot optical film for LCD display includes the following steps:

[0071] The first step, prepare the inner coating glue: Place the polyurethane matrix resin in an environment of 50 °C and heat for 60 min, then weigh 30 parts of the polyurethane matrix resin, 0.05 part of the thermosetting resin containing unsaturated bonds, and 0.1 part of the silane reagent according to the mass ratio, and add them to 100 parts of the diluent solvent. Stir mechanically at 1000 rpm for 30 min until completely dissolved;

[0072] The second step, introduce an inner coating containing organosiloxane on the optical grade base film: Coat the inner coating glue prepared in the first step on the flat base film by roll-to-roll coating, knife coating, dipping or spraying methods to form an inner coating with a thickness of 3 μm, that is, an organosiloxane coating;

[0073] The third step, prepare the quantum dot glue: According to the mass ratio, red quantum dot nanoparticles: green quantum dot nanoparticles: scattering particles:

[0074] matrix resin: initiator = 5:4:20:5:0.01; Mechanically stir the red quantum dot nanoparticles, green quantum dot nanoparticles, scattering particles, matrix resin and initiator at room temperature for 60 min until evenly mixed;

[0075] The fourth step, prepare the prism glue: According to the mass ratio, UV acrylate monomer with monofunctional or bifunctional groups: curing agent

[0076] = 100:0.5; Take a mono-functional or bi-functional UV acrylate monomer and a curing agent and stir at 40 °C for 4 h until evenly mixed;

[0077] Fifth step, on the base film coated with the inner coating prepared in the second step, introduce a quantum dot micro-structure layer composed of a prism glue and a quantum dot glue: Take the quantum dot glue prepared in the third step and the prism glue prepared in the fourth step according to the mass ratio of quantum dot glue:prism glue = 10:20, stir at 100 rpm for 100 min in a heating environment of 40 °C to 50 °C to obtain a micro-structure glue of quantum dots. The micro-structure glue of quantum dots is coated in a roll-to-roll manner, and a rigid roller or a soft film with a micro-structure is selected, and is transferred to the flat base film with a silicone oxide inner coating prepared in the second step through UV curing to form a micro-prism or micro-lens structure film layer with a complete, uniform and continuous distribution. Then, through a high-temperature oven at 60 - 110 °C, the remaining diluent solvent on the film is removed to obtain a quantum dot prism structure layer;

[0078] Sixth step, evaporate or sputter a nano-scale inorganic SiO2 coating on the surface of the quantum dot prism structure layer: Use a vacuum evaporation process to evaporate or sputter a 6 nm inorganic SiO2 coating on the quantum dot prism structure layer, heat the coating material to evaporation by means of electron beam heating, resistance heating, radio frequency induction heating, arc heating or laser heating, and the evaporated coating material condenses on the surface of the quantum dot prism structure layer to form a uniform and dense nano-scale inorganic SiO2 coating;

[0079] Seventh step, configure a blank filling UV acrylate glue layer, i.e., a glue layer: According to the mass ratio of mono-functional acrylate:bi-functional acrylate:tri-functional acrylate = 5:3:1; Take mono-functional, bi-functional, and tri-functional acrylates, mechanically stir and mix at room temperature, with a rotation speed of 500 rpm and a time of 60 min to obtain a glue layer;

[0080] Eighth step: Based on the roll-to-roll coating line, under the irradiation of a 365 nm LED lamp, select an energy of 100 mJ / cm 2 , with a coating speed of 10 m / min, and bond the nano-scale inorganic SiO2 coating and the optical-grade base film through the glue layer to obtain a quantum dot optical film for LCD display.

[0081] In the first step, the main resin component of the inner coating glue is a thermosetting resin containing unsaturated bonds. The thermosetting resin containing unsaturated bonds is one or more of epoxy resin, polyurethane, and acrylic resin. The diluent solvent is ethyl acetate and / or cyclohexanone. The silane reagent is a silane with an unsaturated double bond or a silane containing an epoxy group, specifically: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, mercaptopropylsilane, 3-mercaptopropyltrimethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(β-aminoethyl-γ-aminopropyl)trimethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, diethylenetriaminepropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, n-butylaminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine, 3-(phenylamino)propyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, propyltrimethoxysilane; the refractive index of the inner coating glue is 1.48 - 1.51, and the viscosity is 100 to 300 cps. In the second step, the optical grade base film is polyethylene terephthalate PET, polyethylene naphthalate PEN, polycarbonate PC, polymethyl methacrylate PMMA, polyethylene PE, polyvinylidene fluoride PVDF transparent base film. The thickness of the optical grade base film is 12 - 150 μm. The surface of the optical grade base film is flat, without MD lines and TD lines, and the light transmittance is above 90%. The water and oxygen barrier rate of the optical grade PET base film is 2 - 6 g / (m 2 ·day). The physical barrier performance of water and oxygen is lower than that of commercial barrier films. When used in combination with the inner coating containing a silane reagent, a synergistic effect is produced, increasing the chemical barrier of the silane reagent hydrolysis reaction on the basis of the PET barrier performance and enhancing the water and oxygen barrier performance.

[0082] In the third step, the scattering particles are one or more of silica, titanium dioxide, zinc oxide, and organosilicon, and the particle size of the scattering particles is 100-2000 nm; the red quantum dot nanoparticles and the green quantum dot nanoparticles are oil-soluble quantum dots with organic ligands distributed on the surface. The organic ligands are oleic acid and / or oleylamine / or long-chain organophosphorus compounds. The long-chain organophosphorus compounds are selected from tetradecylphosphine and / or octadecylphosphine; the wavelength range of the red quantum dot nanoparticles is 600-640 nm, and the wavelength range of the green quantum dot nanoparticles is 510-540 nm; according to the mass ratio, the total mass of the red quantum dot nanoparticles and the green quantum dot nanoparticles: the thermosetting resin containing unsaturated bonds = 1:150-200; the addition amount of the scattering particles accounts for 0.01-0.03% of the total mass of the red quantum dot nanoparticles, the green quantum dot nanoparticles, and the thermosetting resin containing unsaturated bonds; the matrix resin is one or more of UV acrylate type, epoxy resin, and polyurethane; the inorganic crystal composition of the red quantum dot nanoparticles and the green quantum dot nanoparticles is one or more of CdSe, CdS, CdZnS, ZnSe, and InP, and organic ligands are distributed on the surface.

[0083] In the fourth step, the refractive index of the prism glue is 1.48-1.51, and the viscosity is 50-300 cps; the monofunctional monomers are one or more of caprolactone acrylate, 2-phenoxyethyl acrylate, o-phenylphenoxyethyl acrylate, and isobornyl acrylate; the difunctional monomers are one or more of dipropylene glycol diacrylate, tripropylene glycol diacrylate, and neopentyl glycol diacrylate; the curing agent is TOP or TOP-L.

[0084] In the fifth step, the microstructure in the quantum dot microstructure glue is a microprism or microlens structure. The microprism or microlens structure is formed by curing acrylate glues with different refractive indices. Through the microprism or microlens structure, light in the horizontal or vertical direction can be converged and emitted along the direction of the LCD screen, efficiently collecting the light from the backlight source. Through the transfer method, the microstructure is transferred to the target base film. There are two ways to realize the microstructure: one is through transfer printing with a copper-plated roller engraved with the microstructure, and the other is through flipping a soft film with the microstructure. For the copper-plated roller with the microstructure, a cutting tool is used to precisely engrave the surface of the copper-plated roller to control and realize various parameters of the microprisms, including: the apex angle of the microprism, the pitch of the prism, and the bottom side length of the prism. Finally, the microstructure on the copper-plated roller is transferred onto the target base film. For the soft film, first, the copper-plated roller with the microstructure can be used for transfer printing to prepare a soft film with the microstructure, and these master films serve as the soft films. Then, through reverse transfer printing of the soft film, the microstructure is obtained on the target base film. The microprism or microlens structure formed by curing the quantum dot microstructure glue, different microstructures are realized through transfer printing with a copper-plated roller engraved with the microstructure or through flipping a soft film with the microstructure. The pitch of the microprism structure (bottom side length) is 40 μm, the height of the prism is 10 - 35 μm, and the included angle of the prism apex angle is 120°. The microlens is a hemispherical structure formed by a resin glue, and its diameter is 20 - 50 μm.

[0085] In the sixth step, the evaporation coating material is a high-purity oxide with a high melting point and low vapor pressure, specifically one or several of silicon dioxide, titanium dioxide, zinc oxide, and aluminum oxide. The thickness of the nanoscale inorganic SiO2 coating is 6 nm. With a nanoscale thickness, SiO2 itself has a dense structure, which can prevent molecules such as moisture and oxygen in the environment from entering the prism structure, improving the stability of the prism structure and ensuring the stability of the quantum dots in the prism.

[0086] The monofunctional acrylate is one or several of methyl acrylate, ethyl acrylate, and isopropyl acrylate. The difunctional acrylate is one or several of dipropylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,6 - hexanediol diacrylate. The trifunctional acrylate is polyurethane acrylate and / or trimethylolpropane triacrylate. The thickness of the glue layer is 20 - 50 μm, and the refractive index is 1.51 - 1.53.

[0087] The quantum dot optical film prepared according to Example 2 is used in an LCD backlight module. Figure 7 This is the backlight application architecture diagram of the quantum dot optical film for LCD display in this application. The basic structure from bottom to top is: blue backlight source, quantum dot optical film, TFT - LCD panel.

[0088] Example 3

[0089] A preparation method of a quantum dot optical film for LCD display, comprising the following steps:

[0090] The first step is to prepare the inner coating glue: After heating the polyurethane matrix resin at 50 °C for 50 min, weigh 15 parts of the polyurethane matrix resin, 0.03 parts of the thermosetting resin containing unsaturated bonds, and 0.05 parts of the silane reagent according to the mass ratio, and add them to 100 parts of the diluent solvent. Stir mechanically at 1000 rpm for 10 min until completely dissolved:

[0091] The second step is to introduce an inner coating containing organosiloxane on the optical grade base film: The inner coating glue prepared in the first step is coated on the flat base film by roll-to-roll coating, knife coating, dipping or spraying methods to form an inner coating with a thickness of 2 μm, that is, an organosiloxane coating;

[0092] The third step is to prepare the quantum dot glue: According to the mass ratio, red quantum dot nanoparticles: green quantum dot nanoparticles: scattering particles:

[0093] matrix resin: initiator = 3:2:15:1:0.05; Mechanically stir the red quantum dot nanoparticles, green quantum dot nanoparticles, scattering particles, matrix resin and initiator at room temperature for 30 min until evenly mixed;

[0094] The fourth step is to prepare the prism glue: According to the mass ratio, the UV acrylate monomer with monofunctional or bifunctional groups: curing agent

[0095] = 100:0.1 - 0.5; Take the UV acrylate monomer with monofunctional or bifunctional groups and the curing agent and stir at 40 °C for 3 h,

[0096] until evenly mixed;

[0097] The fifth step is to introduce a quantum dot microstructural layer composed of prism glue and quantum dot glue on the base film coated with the inner coating prepared in the second step: According to the mass ratio of quantum dot glue: prism glue = 1:50, take the quantum dot glue prepared in the third step and the prism glue prepared in the fourth step, stir at 200 rpm for 120 min in a heating environment of 40 °C to 50 °C to obtain the microstructural glue of the quantum dots. The microstructural glue of the quantum dots is coated by roll-to-roll coating, and a rigid roller or soft film with a microstructure is selected, and transferred to the flat base film with an organosiloxane inner coating prepared in the second step by UV curing to form a film layer with a complete, uniform and continuously distributed micro prism or micro lens structure. Then, pass through a high-temperature oven at 60 - 110 °C to remove the remaining diluent solvent on the film to obtain a quantum dot prism structure layer;

[0098] Step 6: Evaporate or sputter a nanoscale inorganic SiO2 coating on the surface of the quantum dot prism structure layer: Use a vacuum evaporation process to evaporate or sputter a 4-nm inorganic SiO2 coating on the quantum dot prism structure layer. Heat the coating material to evaporation by means of electron beam heating, resistance heating, radio frequency induction heating, arc heating, or laser heating. The evaporated coating material condenses on the surface of the quantum dot prism structure layer to form a uniform and dense nanoscale inorganic SiO2 coating.

[0099] Step 7: Prepare a blank-filling UV acrylate glue layer, i.e., the glue layer: According to the mass ratio, monofunctional acrylate: difunctional acrylate: trifunctional acrylate = 4:2.5:1. Take monofunctional, difunctional, and trifunctional acrylates and mechanically stir and mix them at room temperature at a rotation speed of 300 rpm for 30 minutes to obtain the glue layer.

[0100] Step 8: Based on the roll-to-roll coating line, under the irradiation of a 365-nm LED lamp, select an energy of 150 mJ / cm 2 , with a coating speed of 10 m / min, and bond the nanoscale inorganic SiO2 coating to the optical-grade base film through the glue layer to obtain a quantum dot optical film for LCD display.

[0101] In the first step, the main resin component of the inner coating glue is a thermosetting resin containing unsaturated bonds. The thermosetting resin containing unsaturated bonds is one or more of epoxy resin, polyurethane, and acrylic resin. The diluent solvent is ethyl acetate and / or cyclopropanone. The silane reagent is a silane with an unsaturated double bond or a silane containing an epoxy group, specifically: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, mercaptopropylsilane, 3-mercaptopropyltrimethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(β-aminoethyl-γ-aminopropyl)trimethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, diethylenetriaminepropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, n-butylaminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine, 3-(phenylamino)propyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, propyltrimethoxysilane; the refractive index of the inner coating glue is 1.48 - 1.51, and the viscosity is 100 to 300 cps.

[0102] In the second step, the optical grade base film is a transparent base film of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene (PE), or polyvinylidene fluoride (PVDF). The thickness of the optical grade base film is 12 - 150 μm. The surface of the optical grade base film is flat, without MD lines and TD lines, and the light transmittance is above 90%. The water and oxygen barrier rate of the optical grade PET base film is 2 - 6 g / (m 2 ·day).

[0103] In the third step, the scattering particles are one or more of silicon dioxide, titanium dioxide, zinc oxide, and organosilicon. The particle size of the scattering particles is 100 - 2000 nm; for the red quantum dot nanoparticles and green quantum dot nanoparticles, oil-soluble quantum dots with organic ligands on the surface are selected. The organic ligands are oleic acid and / or oleylamine and / or long-chain organophosphorus compounds. The long-chain organophosphorus compounds are selected from tetradecylphosphine and / or octadecylphosphine; the wavelength range of the red quantum dot nanoparticles is 600 - 640 nm, and the wavelength range of the green quantum dot nanoparticles is 510 - 540 nm; according to the mass ratio, the total mass of the red quantum dot nanoparticles and the green quantum dot nanoparticles: the thermosetting resin containing unsaturated bonds = 1:150 - 200; the addition amount of the scattering particles accounts for 0.01 - 0.03% of the total mass of the red quantum dot nanoparticles, the green quantum dot nanoparticles, and the thermosetting resin containing unsaturated bonds; the matrix resin is one or more of UV acrylate type, epoxy resin, and polyurethane; the inorganic crystal compositions of the red quantum dot nanoparticles and the green quantum dot nanoparticles are one or more of CdSe, CdS, CdZnS, ZnSe, and InP, and there are organic ligands on the surface.

[0104] In the fourth step, the refractive index of the prism glue is 1.48 - 1.51, and the viscosity is 50 - 300 cps; the monofunctional monomers are one or more of caprolactone acrylate, 2-phenoxyethyl acrylate, o-phenylphenoxyethyl acrylate, and isobornyl acrylate; the bifunctional monomers are one or more of dipropylene glycol diacrylate, tripropylene glycol diacrylate, and neopentyl glycol diacrylate; the curing agent is TOP or TOP-L.

[0105] In the fifth step, the microstructure in the quantum dot microstructure glue is a microprism or microlens structure. The microprism or microlens structure is formed by curing acrylate glues with different refractive indices. Through the microprism or microlens structure, light in the horizontal or vertical direction can be converged and emitted along the direction of the LCD screen, efficiently collecting the light of the backlight source. Through the transfer method, the microstructure is transferred to the target base film. There are two ways to realize the microstructure. One is realized by transferring through a copper-plated roller engraved with the microstructure, and the other is realized by flipping a soft film with the microstructure. For the copper-plated roller with the microstructure, a tool is used to precisely engrave the surface of the copper-plated roller to control and realize various parameters of the microprisms, including: the apex angle of the microprism, the pitch of the prism, and the bottom side length of the prism. Finally, the microstructure on the copper-plated roller is transferred onto the target base film. For the soft film, first, the copper-plated roller with the microstructure can be transferred to prepare a soft film with the microstructure, and these master films serve as the soft films. Then, through reverse transfer of the soft film, the microstructure is obtained on the target base film. The microprism or microlens structure formed by curing the quantum dot microstructure glue, different microstructures are realized by transferring through a copper-plated roller engraved with the microstructure or by flipping a soft film with the microstructure. The pitch of the microprism structure, the bottom side length is 30 μm, the height of the prism is 15 μm, and the included angle of the prism apex angle is 90°. The microlens is a hemispherical structure formed by a resin glue, and its diameter is 20 - 50 μm.

[0106] In the sixth step, the evaporation coating material is a high-purity oxide with a high melting point and low vapor pressure, specifically one or several of silicon dioxide, titanium dioxide, zinc oxide, and aluminum oxide. The thickness of the nanoscale inorganic SiO2 coating is 4 nm. The thickness is nanoscale, and SiO2 itself has a dense structure, which can prevent molecules such as moisture and oxygen in the environment from entering the prism structure, improving the stability of the prism structure and ensuring the stability of the quantum dots in the prism.

[0107] The monofunctional acrylate is one or several of methyl methacrylate, ethyl acrylate, and isopropyl acrylate. The difunctional acrylate is one or several of dipropylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,6-hexanediol diacrylate. The trifunctional acrylate is polyurethane acrylate and / or trimethylolpropane triacrylate. The thickness of the glue layer is 20 - 50 μm, and the refractive index is 1.51 - 1.53.

[0108] The quantum dot optical film prepared according to Example 3 is used in the LCD backlight module. Figure 7 This is the backlight application architecture diagram of the quantum dot optical film for LCD display in this application. The basic structure from bottom to top is: blue backlight source, quantum dot optical film, TFT-LCD panel, etc.

[0109] Experimental data:

[0110] In this proposal, a quantum dot film with a conventional "sandwich" structure was prepared using the traditional roll-to-roll process, and a quantum dot optical film prepared according to Example 1 (where the glue layer has a microprism structure and the microprism structure contains two types of quantum dots, red and green) was used, and the changes in key parameters such as chromaticity coordinate X, chromaticity coordinate Y, brightness, failure edge, in-plane uniformity, etc. were evaluated under a reliability experiment at 60°C / 90% RH of high temperature and high humidity. The specific structural parameters are as follows:

[0111] The overall thickness of the prepared quantum dot film with a conventional "sandwich" structure is 300 μm. From top to bottom, it is an upper barrier film with a thickness of 100 μm; a glue layer containing red and green quantum dots with a thickness of 100 μm; a lower barrier film with a thickness of 100 μm; and the color point of the whole film is (0.313, 0.329).

[0112] The thickness of the quantum dot optical film prepared according to Example 1 is 300 μm. From top to bottom, it is an upper PET base film with a thickness of 100 μm; a glue layer containing red and green quantum dots with a thickness of 100 μm. The glue layer contains uniformly distributed and continuously arranged microprism structures. The pitch (bottom side length) of the microprisms is 50 μm, the included angle of the microprism structure is 90°, the thickness of the organosiloxane coating is 0.5 μm, and the thickness of the nanoscale inorganic SiO2 coating is 2 nm; a lower PET base film with a thickness of 100 μm; and the color point of the whole film is (0.315, 0.328).

[0113] The prepared quantum dot film with a conventional "sandwich" structure and the quantum dot optical film prepared according to Example 1 were placed in a high temperature and high humidity chamber (60°C / 90% RH) for reliability testing, and at 0 h, 1000 h, and 2000 h, the changes in key parameters of the samples were evaluated. The results are shown in the following table.

[0114] The above data show that: The quantum dot optical film prepared according to Example 1 of the present invention has basically the same initial optical performance as the quantum dot film with a conventional "sandwich" structure; moreover, in Example 1, an ordinary optical grade polymer base film was used to replace the expensive imported barrier film, greatly reducing the manufacturing cost; at the same time, after 2000 h of reliability testing, the chromaticity coordinates of the quantum dot optical film prepared according to Example 1 are more stable, the brightness loss is smaller, and the failure edge is also smaller. This shows that the overall performance of this product exhibits better optical stability than the quantum dot film with a conventional "sandwich" structure.

[0115]

[0116] The above description of the examples is provided to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a quantum dot optical film for LCD display, characterized in that: The following steps are involved: The first step is to prepare the inner coating glue: heat the polyurethane matrix resin at 40-60°C for 30-60 minutes, weigh 5-30 parts of the polyurethane matrix resin, 0.01-0.05 parts of the thermosetting resin containing unsaturated bonds, and 0.01-0.1 parts of the silane reagent according to the mass ratio, add them to 100 parts of the diluent solvent, and mechanically stir at 200-1000 rpm for 10-30 minutes until they are completely dissolved; The second step is to introduce an inner coating containing organic siloxane on the optical-grade base film: the inner coating glue prepared in the first step is coated on the flat optical-grade base film by roll-to-roll coating, doctor blade coating, dipping or spraying to form an inner coating with a thickness of 0.5-3 μm, i.e., an organic siloxane coating; The third step is to prepare quantum dot glue: the mass ratio of red quantum dot nanoparticles: green quantum dot nanoparticles: scattering particles: matrix resin: initiator = (1-5): (1-4): (10-20): (1-5): (0.01-0.05); the red quantum dot nanoparticles, green quantum dot nanoparticles, scattering particles, matrix resin and initiator are mechanically stirred at room temperature for 30-120 minutes until they are uniformly mixed; Step 4: prepare prism glue: the mass ratio of monofunctional or difunctional UV acrylate monomer: curing agent = 100:0.1-0.5; take the monofunctional or difunctional UV acrylate monomer and the curing agent and stir them at 40° C. for 2-4 hours until they are evenly mixed; The fifth step is to introduce a quantum dot prism structure layer composed of prism glue and quantum dot glue on the optical-grade base film coated with the inner coating prepared in the second step: the mass ratio of quantum dot glue: prism glue = (1-10): (20-50) The quantum dot glue prepared in the third step and the prism glue prepared in the fourth step are stirred at 50-200rpm for 60-240min under a heating environment of 40°C to 50°C to obtain a quantum dot microstructure glue. The quantum dot microstructure glue is coated in a roll-to-roll manner, using a copper-plated roller or soft film with a microstructure, and is transferred to the flat optical-grade base film with an organic siloxane inner coating prepared in the second step through UV curing to form a microprism or microlens structure film layer with a complete structure, uniform and continuously distributed, and then passed through a high-temperature oven at 60-110°C to remove the remaining diluent solvent on the film to obtain a quantum dot prism structure layer; Step 6: Evaporating or sputtering a nanometer-scale inorganic SiO2 coating on the surface of the quantum dot prism structure layer: using a vacuum evaporation process to evaporate or sputter a 2-6nm inorganic SiO2 coating on the quantum dot prism structure layer, heating the coating material to evaporate by electron beam heating, resistance heating, radio frequency induction heating, arc heating or laser heating, and condensing the evaporated coating material on the surface of the quantum dot prism structure layer to form a uniform and dense nanometer-scale inorganic SiO2 coating; Step 7: Prepare a blank filling UV acrylate adhesive layer, i.e., a glue layer: the mass ratio of monofunctional acrylate: difunctional acrylate: trifunctional acrylate = 3-5:2-3:1; take monofunctional acrylate, difunctional acrylate, and trifunctional acrylate, and mix them by mechanical stirring at room temperature, with a rotation speed of 200-500 rpm and a stirring time of 30-60 min to prepare a glue layer; Step 8: Based on the roll-to-roll coating line, under the irradiation of 365nm LED light, the energy is selected to be 50-200mJ / cm 2 The coating speed is 5-15m / min, and the nano-scale inorganic SiO2 coating is bonded to the optical-grade base film through the glue layer to produce a quantum dot optical film for LCD display.

2. The method for preparing a quantum dot optical film for LCD display according to claim 1, characterized in that: In the first step, the main resin component of the inner coating glue is a thermosetting resin containing unsaturated bonds, and the thermosetting resin containing unsaturated bonds is one or more of epoxy resin, polyurethane, and acrylic resin; the diluent solvent is ethyl acetate and / or cyclopropanone; the silane reagent is a silane with unsaturated double bonds or a silane containing an epoxy group, specifically: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, mercaptopropylsilane, 3-mercaptopropyltrimethylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, One or more of oxysilane, N-(β-aminoethyl-γ-aminopropyl)trimethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, diethylenetriaminopropyltrimethoxysilane, 3-ureapropyltrimethoxysilane, n-butylaminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine, 3-(phenylamino)propyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and propyltrimethoxysilane; the refractive index of the inner coating glue is 1.48-1.51, and the viscosity is 100 to 300cps.

3. The method for preparing a quantum dot optical film for LCD display according to claim 1, characterized in that: In the second step, the optical grade base film is one or more of polyethylene terephthalate PET, polyethylene naphthalate PEN, polycarbonate PC, polymethyl methacrylate PMMA, polyethylene PE, polyvinylidene fluoride PVDF transparent base films, the thickness of the optical grade base film is 12-150 μm, the surface of the optical grade base film is flat, without MD lines and TD lines, and the light transmittance is above 90%, and the water and oxygen barrier rate of the optical grade PET base film is 2-6 g / (m 2 ·day).

4. The method for preparing a quantum dot optical film for LCD display according to claim 1, characterized in that: In the third step, the scattering particles are one or more of silicon dioxide, titanium dioxide, zinc oxide, and organic silicon, and the particle size of the scattering particles is 100-2000nm; the red quantum dot nanoparticles and the green quantum dot nanoparticles are selected from oil-soluble quantum dots with organic ligands distributed on the surface, and the organic ligands are one or more of oleic acid, oleylamine, and long-chain organic phosphine compounds, and the long-chain organic phosphine compounds are tetradecylphosphine and / or octadecylphosphine; the wavelength range of the red quantum dot nanoparticles is 600-640nm, and the wavelength range of the green quantum dot nanoparticles is 510-540nm; according to the mass ratio of the red quantum dot nanoparticles, the green quantum dot nanoparticles are selected from oil-soluble quantum dots with organic ligands distributed on the surface, and the organic ligands are one or more of oleic acid, oleylamine, and long-chain organic phosphine compounds. The total mass of quantum dot nanoparticles and green quantum dot nanoparticles: thermosetting resin containing unsaturated bonds = 1:150-200; the added amount of scattering particles accounts for 0.01-0.03% of the total mass of red quantum dot nanoparticles, green quantum dot nanoparticles and thermosetting resin containing unsaturated bonds; the matrix resin is one or more of UV acrylate type, epoxy resin, and polyurethane; the inorganic crystal composition of the red quantum dot nanoparticles and the green quantum dot nanoparticles is one or more of CdSe, CdS, CdZnS, ZnSe, InP, and organic ligands are distributed on the surface.

5. The method for preparing a quantum dot optical film for LCD display according to claim 1, characterized in that: In the fourth step, the refractive index of the prism glue is 1.48-1.51, and the viscosity is 50-300cps; the monofunctional UV acrylate monomer is one or more of caprolactone acrylate, 2-phenoxyethyl acrylate, o-phenylphenoxyethyl acrylate, and isobornyl acrylate; the difunctional UV acrylate monomer is one or more of dipropylene glycol diacrylate, tripropylene glycol diacrylate, and neopentyl glycol diacrylate; and the curing agent is TOP or TOP-L.

6. The method for preparing a quantum dot optical film for LCD display according to claim 1, characterized in that: The fifth step of the microprism or microlens structure is formed by curing acrylic glue with different refractive indices. Through the microprism or microlens structure, horizontal or vertical light can be gathered and light can be emitted along the direction of the LCD screen to efficiently collect the light from the backlight source. There are two ways to realize the microprism or microlens: one is to transfer it through a copper-plated roller engraved with a microstructure, and the other is to flip the soft film with a microstructure. For the copper-plated roller with a microstructure, a tool is used to perform precision engraving on the surface of the copper-plated roller to control and realize various parameters of the microprism, including: the top angle of the microprism, the pitch of the microprism, and the bottom side length of the prism; finally, by transferring the microstructure on the copper-plated roller, Print onto a flat optical-grade base film; for a soft film, first transfer a copper-plated roller with a microstructure to prepare a soft film with a microstructure, and these mother films are used as soft films; then, the microstructure is obtained on the flat optical-grade base film by reverse printing of the soft film, and the micro-structure glue of the quantum dots is cured to form a micro-prism or micro-lens structure. Different microstructures are achieved by transferring a copper-plated roller engraved with a microstructure, or by flipping a soft film with a microstructure; the pitch bottom side length of the micro-prism structure is 20-70μm, the height of the prism is 10-35μm, and the angle of the prism vertex is 70-120°; the microlens is a hemispherical structure formed by resin glue, and its diameter is 20-50μm.

7. The method for preparing a quantum dot optical film for LCD display according to claim 1, characterized in that: In the sixth step, the coating material is a high-purity oxide with a high melting point and a low vapor pressure. Silicon dioxide can be replaced by one or more of titanium dioxide, zinc oxide, and aluminum oxide. The thickness of the nano-scale inorganic SiO2 coating is 2-6nm. The thickness is nanometer-scale, and SiO2 itself has a dense structure, which can prevent moisture and oxygen molecules in the environment from entering the prism structure, thereby improving the stability of the prism structure and ensuring the stability of the quantum dots in the prism.

8. The method for preparing a quantum dot optical film for LCD display according to claim 1, characterized in that: The monofunctional acrylate is one or more of methacrylate, ethyl acrylate, and isopropyl acrylate; the difunctional acrylate is one or more of tripropylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,6-hexanediol diacrylate; the trifunctional acrylate is polyurethane acrylate and / or trimethylolpropane triacrylate; the thickness of the glue layer is 20-50 μm, and the refractive index is 1.51-1.

53.

9. A quantum dot optical film for LCD display prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The structures of the quantum dot optical film for LCD display are respectively from bottom to top: an optical-grade base film, a glue layer, a nano-scale inorganic SiO2 coating, a quantum dot prism structure layer, an organic siloxane inner coating, and an optical-grade base film.

10. The quantum dot optical film for LCD display according to claim 9, characterized in that: The refractive index of the quantum dot prism structure layer is 1.51-1.53.

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