Integrated quantum dot enhanced backlight film and preparation method and application thereof

Abstract

The invention discloses an integrated quantum dot enhanced backlight film and a preparation method and application thereof, and belongs to the technical field of display devices. Comprising a quantum dot diffusion film; the quantum dot diffusion film comprises a quantum dot adhesive layer and two composite functional layers which are symmetrically arranged on the two sides of the quantum dot adhesive layer in an attached mode. One surface, facing the quantum dot adhesive layer, of the composite functional layer is a barrier layer, and the other surface is an extruded PET diffusion film layer. A traditional extrusion type diffusion plate is replaced with an extrusion type PET diffusion film with the thinner size, a blocking layer is directly deposited on the surface of the extrusion type PET diffusion film through the deposition technology, the existing technology that a diffusion film is attached to a thin blocking film in the industry is replaced, meanwhile, a quantum dot functional layer is coated with the UV light curing technology, and therefore the thickness of the diffusion film is reduced. The process is simplified, the film material is thinned, the cost is reduced, roll-to-roll lamination with other diffusion films, composite bright enhancement films and the like can be realized, and multiple functions can be realized by only using one composite film material in backlight.

Description

Technical Field

[0001] The present application relates to an integrated quantum dot enhanced backlight film and a preparation method and application thereof, belonging to the technical field of display devices. Background Art

[0002] The backlight module of a liquid crystal display (LCD) is one of its key components, which is mainly responsible for providing a uniform backlight source to ensure that the image on the final screen is clearly displayed. Its structure usually includes an LED light source, a light guide plate or a diffuser plate, and an optical film group. Usually, the optical film group has a multi-layer optical film structure, including a single-function film such as a lower diffuser film, a first prism film, a second prism film, a polarizing light enhancement film, and an upper diffuser film, or a composite film in which multiple films are bonded together. In order to reduce production and transportation costs and reduce the overall thickness of the backlight module, the prior art bonds optical films of various functions together to form a functional composite film. For example, in the art, a film formed by bonding a layer of diffuser film and a layer of prism film is referred to as a DOP composite film (Diffuser on Prism), and different types of independent films are bonded into a whole for use, which reduces the assembly process.

[0003] The application of quantum dot technology in LCD backlight is an important progress in the field of display technology in recent years. Quantum dots are nano-scale semiconductor particles with excellent optical properties. When excited by blue light or ultraviolet light, they can emit high-purity light of a specific wavelength. This property makes quantum dots very suitable for enhancing the color performance of LCD displays and improving the display color gamut. Quantum dot optical film is a technology that encapsulates quantum dots in a thin film. The quantum dot optical film converts part of the blue light in the blue LED light source into red and green light, and combines the remaining blue light to form a complete RGB white light backlight source. When the quantum dot optical film is applied to the liquid crystal backlight display, the entire backlight structure is: LED light source, light guide plate or diffuser, quantum dot optical film, diffuser film, light-enhancing composite film, liquid crystal module, etc. Due to the addition of quantum dot optical film, some problems have also been brought about, such as the relatively high production cost of quantum dot optical film, which is much higher than the traditional backlight solution; the production and integration of quantum dot optical film into the existing LCD manufacturing process is relatively complicated, and it is easy to be damaged during transportation and assembly. At present, the diffusion plate, quantum dot optical film, and light-enhancing composite film are all independent of each other and assembled separately to make LCD backlight modules, which have problems such as complex assembly process and high cost. In addition, in order to reduce the cost of quantum dot technology application in backlight modules, the quantum dot light conversion function is combined with the diffusion plate, and the multi-layer co-extrusion technology of the diffusion plate is used to achieve uniform dispersion of quantum dots in the diffusion plate. The quantum dot diffusion plate eliminates the complex coating process of the quantum dot optical film and does not require a barrier film, thus significantly reducing the cost of the backlight module. However, during the extrusion process of the diffusion plate, quantum dots need to experience a high temperature of more than 230°C, which will cause the organic ligand material on the surface of the quantum dots to fall off, resulting in a decrease in the light conversion efficiency of the quantum dots. In addition, because there is no effective water and oxygen barrier layer in the quantum dot diffusion plate, the long-term service life of the quantum dot diffusion plate is low, and there is a great risk of failure. In view of the high cost, complex assembly, and high risk of failure in the application of quantum dot optical films and quantum dot diffusion plates in liquid crystal backlights. Summary of the invention

[0004] In order to solve the problem that it is difficult to achieve high optical performance while taking into account simple assembly and low cost in the existing LCD backlight module technology, the present application provides an integrated quantum dot enhanced backlight film and its preparation method and application, using a thinner extruded PET diffusion film to replace the traditional extruded diffusion plate, and using deposition technologies such as ALD / PVD / CVD to directly deposit a barrier layer on the surface of the extruded PET diffusion film, replacing the current diffusion film laminating thin barrier film process in the industry, to achieve process simplification, film thinning and cost reduction. The quantum dot functional layer is coated between two extruded PET diffusion films with barrier layers using UV light curing technology to achieve the same light conversion and light diffusion effects as the current quantum dot diffusion plate, with lower overall cost, and the barrier layers on both sides of the quantum dots have a longer service life. Furthermore, the quantum dot diffusion film can also be roll-to-roll laminated with other diffusion films and composite light enhancement films, so that only one composite film material is used in the backlight to meet the functions of light diffusion, quantum dot light conversion and light increment.

[0005] This application adopts the following technical solutions:

[0006] According to one aspect of the present application, there is provided an integrated quantum dot enhanced backlight film, comprising a quantum dot diffusion film;

[0007] The quantum dot diffusion film comprises a quantum dot glue layer and two composite functional layers symmetrically laminated on both sides of the quantum dot glue layer;

[0008] The side of the composite functional layer facing the quantum dot glue layer is a barrier layer, and the other side is an extruded PET diffusion film layer;

[0009] A brightness enhancement composite film is laminated on at least one side of the quantum dot diffusion film.

[0010] In the present application, a barrier layer is prepared on the surface of an extruded PET diffusion film and used as a substrate. Quantum dot concentrate or quantum dot powder is evenly mixed with UV glue to form quantum dot UV glue. A quantum dot UV glue layer of a certain thickness is coated between two layers of extruded PET diffusion films with barriers. After UV light curing, a quantum dot diffusion film with a symmetrical structure is formed, which can be produced continuously in a roll-to-roll manner.

[0011] Optionally, the brightness enhancement composite film is composited on the surface of the quantum dot diffusion film by bonding glue;

[0012] The side of the brightness enhancement composite film facing the quantum dot adhesive layer is a PET base film layer.

[0013] In the present application, PVD / CVD / ALD and other technologies are directly used on the surface of the extruded PET diffusion film to deposit a dense oxide film on the surface of the film to form a barrier layer to achieve a high-efficiency water and oxygen barrier effect, thereby omitting the composite cost of the traditional barrier film.

[0014] Optionally, the barrier layer is a metal oxide layer deposited on an extruded PET diffusion film layer;

[0015] Optionally, the material of the barrier film is selected from at least one of Al2O3, TiO2, HfO2, and ZrO2.

[0016] Optionally, the barrier film has a thickness of 10 nm to 1000 nm.

[0017] Optionally, the water vapor barrier rate of the barrier film is>10 -1 g / m 2 / sky.

[0018] Optionally, the oxygen barrier rate of the barrier film is>10 -1 cm 3 / m 2 / sky.

[0019] In this application, a low-cost extruded PET diffusion film is used as the diffusion functional layer. Compared with the method of coating organic / inorganic diffusion particles on the traditional diffusion film to enhance the light diffusion ability, the extruded PET diffusion film uses the extrusion technology to prepare a porous microstructure on the surface of the PET intermediate layer, which not only improves the problems of uneven brightness, shedding of diffusion particles, easy friction, and severe warping of the traditional diffusion film, but also has a light transmittance, haze, ink adhesion, and surface impedance that are not lower than those of the traditional diffusion film. In addition to the cost advantage, the extruded PET diffusion film also has the characteristics of high stiffness and not easy to collapse, and has a good diffusion effect on the lamp beads and more uniform brightness.

[0020] Optionally, the extruded PET diffusion film layer includes a diffusion function layer and two PET optical layers symmetrically arranged on both sides of the diffusion function layer.

[0021] Optionally, the diffusion function layer is a PET film layer containing a large amount of diffusion particles.

[0022] Optionally, the extruded PET diffusion film has a thickness of 50 μm to 500 μm.

[0023] Optionally, the extruded PET diffusion film has a haze of 10%-99%.

[0024] Optionally, the transmittance of the extruded PET diffusion membrane is 30%-90%.

[0025] Optionally, the quantum dot glue layer includes a cured UV-curable glue matrix and quantum dot powder particles and quantum dot diffusion particle particles dispersed inside.

[0026] Optionally, the quantum dot powder particles are selected from at least one of quantum dot particles and composite particles of quantum dots and polymers or inorganic oxides.

[0027] Optionally, the material of the quantum dot diffusion particles is selected from at least one of titanium dioxide, silicon dioxide and zirconium oxide.

[0028] Optionally, the quantum dot glue layer has a thickness of 30 to 150 μm.

[0029] Optionally, the quantum dots in the quantum dot powder are selected from group IV, II-VI, IV-VI, III-V quantum dots and multi-element quantum dots.

[0030] Optionally, the quantum dots in the quantum dot powder are selected from at least one of carbon-containing quantum dots, silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, indium phosphide quantum dots, indium arsenide quantum dots, inorganic perovskite quantum dots and organic-inorganic hybrid perovskite quantum dots.

[0031] According to another aspect of the present application, a method for preparing the above-mentioned integrated quantum dot enhanced backlight film is provided, comprising the following steps:

[0032] S1, obtaining an extruded PET diffusion film and a quantum dot coating liquid;

[0033] S2, depositing a barrier layer on one side of the extruded PET diffusion film to obtain a composite functional layer;

[0034] S3, making one side of the barrier layer on the two composite functional layers face each other, coating the quantum dot coating liquid between the barrier films on both sides, and curing to obtain an integrated quantum dot diffusion film;

[0035] S4, compounding at least one side of the quantum dot diffusion film and the brightness enhancement composite film by bonding glue to obtain the integrated quantum dot enhanced backlight film.

[0036] Optionally, in step S1, the method for preparing the extruded PET diffusion membrane comprises the following steps:

[0037] The optical PET raw material is mixed with the diffusion particles, extruded into a film by three-layer co-extrusion, and then four-way stretching is performed to obtain the extruded PET diffusion film.

[0038] Optionally, the optical PET raw material is polyethylene terephthalate.

[0039] Optionally, the diffusion particle raw material is selected from at least one of silicon dioxide, titanium dioxide, barium sulfate, organic silicon or calcium carbonate.

[0040] Optionally, the conditions for the three-layer co-extrusion include: a temperature of 100° C. to 200° C. and an extrusion speed of 0.5 to 5 m / s.

[0041] Optionally, the four-way stretching conditions include: longitudinal stretching at a stretching ratio of 3.0 to 3.5, and transverse stretching at a stretching ratio of 3.5 to 4.

[0042] Optionally, in step S3, the coating method is selected from one of blade coating, slit coating and roller coating.

[0043] Optionally, in step S1, the quantum dot coating liquid includes UV curing glue and quantum dot powder particles dispersed in the UV curing glue.

[0044] Optionally, the components of the UV curing adhesive include 170 to 200 parts by weight of epoxy resin, 40 to 130 parts by weight of reactive diluent, 0.5 to 14 parts by weight of cationic initiator, and 1 to 6 parts by weight of auxiliary agent.

[0045] Optionally, the components of the quantum dot coating solution further include 1 wt% to 30 wt% of light scattering particles.

[0046] Optionally, the epoxy resin is selected from at least one of alicyclic epoxy resin and glycidyl epoxy resin.

[0047] Optionally, the alicyclic epoxy resin includes at least one of bis(di(3,4-epoxycyclohexyl)methyl)hexanedioic acid, poly[(2-oxiranyl)-1,2-cyclohexanediol]2-ethyl-2-(hydroxymethyl)-1,3-propylene glycol ether (3:1), 1,4-bis(3,4-epoxycyclohexyl-1-methoxy)methylbenzene, 1,4-bis(3,4-epoxycyclohexyl-1-methoxy)butane, epoxidized polybutadiene (EPOLEAD PB series of Japan Daicel), dicyclopentadiene dioxide, and 3,4-epoxycyclohexanecarboxylic acid methyl ester.

[0048] Optionally, the glycidyl epoxy resin is selected from at least one of hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F glycidyl ether, hydrogenated bisphenol E diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, polyethylene glycol glycidyl ether, polypropylene glycol glycidyl ether, and polybutylene glycol glycidyl ether.

[0049] Optionally, the active diluent is selected from at least one of vinyl (propylene) ethers, oxygen heterocyclic active diluents, and glycidyl ethers.

[0050] Optionally, the cationic initiator is selected from a photocationic initiator and / or a thermal cationic initiator.

[0051] Optionally, the photocationic initiator is selected from sulfonium salts such as 4-phenylthiophenyl diphenylsulfonium salt, tris[4-[(4-acetylphenyl)thio]-hexafluorophosphate, tris(4-methoxyphenyl)sulfonium hexafluorophosphate, diphenyl-4-phenylthiophenylsulfonium hexafluoroantimonate, diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, 4-dodecylphenyl diphenylsulfonium hexafluorophosphate, 4,4′-bis(diphenylsulfonium)phenyl sulfide-bis-hexafluoroantimonate, 4,4′-bis[bis(β-hydroxyethoxy)phenylsulfonium]phenyl At least one of thioether-bis-hexafluoroantimonate, 4-[4′-(benzoyl)phenylthio]phenyl-bis-(4-fluorophenyl)sulfonium hexafluoroantimonate, 4-(2-chloro-4-benzoylphenylthio)phenylbis(4-fluorophenyl)sulfonium hexafluoroantimonate; iodonium salts such as diphenyliodonium hexafluoroantimonate, di(4-methylphenyl)iodonium hexafluorophosphate, di(4-tert-butylphenyl)iodonium hexafluorophosphate, tolylcumyliodonium tetrakis(pentafluorophenyl)borate diaryliodonium salts, and ferrocenium salts such as [cyclopentadienyl-iron-isopropylbenzene]hexafluorophosphate.

[0052] Optionally, the thermal cationic initiator is selected from anhydride compounds such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride; imidazole derivatives such as N-(2-(2-methyl-1-imidazolyl)ethyl)urea, N,N'-(2-methyl-1-imidazolylethyl)adipamide, 2-phenyl-4,5-dihydroxymethylimidazole, Hycat TM At least one of AO-4 (DTCS, USA) and CXC-1612 (King's Chemical, USA).

[0053] Optionally, the auxiliary agent is selected from at least one of a leveling agent, a defoaming agent, and an antioxidant.

[0054] Optionally, in step S2, the deposition method is selected from at least one of physical vapor deposition, chemical vapor deposition, and atomic layer deposition.

[0055] Optionally, in step S4, the composite method is roll-to-roll lamination;

[0056] The side of the brightness enhancement composite film facing the quantum dot adhesive layer is a PET base film layer.

[0057] In this application, the light-enhancing composite film refers to an optical composite film with multiple functions such as increment, shielding, and diffusion, which is prepared by a composite process route using two to three optical films according to different application requirements. It can be divided into various types according to the combination of different films: such as DOP (diffuser + light-enhancing film), POP (light-enhancing film + light-enhancing film), DPP (diffuser + light-enhancing film + light-enhancing film), CPP (polarized light-enhancing film + light-enhancing film + light-enhancing film), MOP (microlens + light-enhancing film), POD (light-enhancing film + diffuser), COP (polarized light-enhancing film + light-enhancing film), etc., wherein the diffuser refers to a film layer that uses a surface coating process to coat organic / inorganic diffusion particles on the surface of the base film to enhance the light diffusion function; the light-enhancing film refers to a regular prism pattern formed on the surface of the film material to concentrate the light in the backlight source to emit perpendicular to the film surface, thereby achieving an increase in brightness. The microlens uses a regular microlens structure formed on the surface of the film material to achieve light concentration to emit perpendicular to the film surface, thereby achieving an increase in brightness. The polarization enhancement film polarizes the backlight, outputs polarized light, and reflects the polarized light reflected back by the polarization enhancement film again to achieve a significant increase in the backlight brightness.

[0058] According to another aspect of the present application, there is provided a use of any one of the above-mentioned integrated quantum dot enhanced backlight films or the integrated quantum dot enhanced backlight film obtained according to any one of the above-mentioned preparation methods in a backlight module of a liquid crystal display.

[0059] The beneficial effects of this application include:

[0060] The integrated quantum dot enhanced backlight film provided by the present application uses an extruded PET diffusion film with low preparation cost as a diffusion layer to make a quantum dot diffusion film and a light-enhancing composite film to make an integrated quantum dot enhanced backlight film. This solution is applied in the backlight module of a liquid crystal display, and the overall cost is lower than that of a quantum dot film and a light-enhancing composite film; and the integrated quantum dot enhanced backlight film is conducive to transportation and assembly, and is conducive to production; the integrated quantum dot enhanced backlight film takes into account both the functional protection of quantum dots and the improvement of the service life of quantum dot backlight, and the comprehensive performance is better than that of a quantum dot diffusion plate solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is a schematic diagram of the structure of the extruded PET diffusion film with a barrier layer in this application.

[0062] Figure 2 This is a schematic diagram of the structure of the quantum dot diffusion film of this application.

[0063] Figure 3 This is a schematic diagram of the structure of the integrated quantum dot enhanced backlight film of this application.

[0064] Figure 4 This is the spectrum of sample 1# film of integrated quantum dot enhanced backlight film under blue light excitation.

[0065] Figure 5 This is the spectrum of sample film 2# of integrated quantum dot enhanced backlight film under blue light excitation.

[0066] Figure ID

[0067] 1. Quantum dot diffusion film; 2. Lamination glue; 3. PET base film; 4. Brightness enhancement composite film; 5. Barrier layer; 6. First PET optical layer; 7. Diffusion functional layer; 8. Second PET optical layer; 11. Quantum dot glue layer; 12. First barrier layer; 13. First extruded PET diffusion film; 14. Second barrier layer; 15. Second extruded PET diffusion film; 131. Diffusion functional layer; 132. First PET optical layer; 133. Second PET optical layer. DETAILED DESCRIPTION

[0068] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0069] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0070] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0071] Regarding the following situations or problems in the prior art: usually the diffuser plate / light guide plate, the traditional quantum dot optical film, and the light-enhancing composite film exist independently in the backlight and are stacked in sequence. The cost of the traditional quantum dot optical film is relatively high, about 100 to 150 yuan / ㎡, which is the most expensive quantum dot backlight solution at present. The diffuser plate or light guide plate cannot be bonded with the quantum dot optical film and the light-enhancing composite film above, resulting in each plate and film material needing to be cut, packaged and transported independently, making the assembly of the liquid crystal backlight module complicated, resulting in an increase in the cost of the entire backlight module, and the quantum dot diffuser plate cannot be used in the most widely used side-entry backlight. Another way in the prior art is to use a quantum dot diffuser plate. The quantum dot diffuser plate has no barrier layer, poor long-term stability, and a great risk of failure of the entire machine. In addition, the cost of the quantum dot diffuser plate is high, estimated at 45-50 yuan / ㎡, and requires the investment of new multi-layer co-extrusion equipment. The diffusion plate and the brightness enhancement film are difficult to bond together, and the heat shrinkage rates are inconsistent (the diffusion plate is made of PS material, and the brightness enhancement film is made of PET substrate, and the melting points are quite different), which easily leads to appearance defects such as arching and warping. The bonding efficiency of the plate and film is low, the bonding cost is high (precision alignment is required), and roll-to-roll continuous production cannot be achieved. In response to the above situation, the present application first provides an integrated quantum dot backlight film structure, which integrates optical films with multiple functions such as quantum dot optical film, diffusion film, and brightness enhancement composite film in the quantum dot backlight structure to form a multifunctional composite quantum dot optical film, which has the following advantages: the lowest overall cost, compared with the separate quantum dot optical film solution and quantum dot diffusion plate solution; the whole machine assembly process is simple; the functional protection of QD is taken into account to improve the service life of the backlight.

[0072] Example 1

[0073] Step 1: Obtain an extruded PET diffusion film with a barrier layer:

[0074] Referring to the method of Example 2 in the patent with publication number CN 107132600A, optical PET raw materials are mixed with silica diffusion particles, and then extruded into a film by three-layer co-extrusion. The extrusion temperature is 150°C, the extrusion speed is 1m / s, the longitudinal stretching is performed at a stretching ratio of 3.0, and the transverse stretching is performed at a stretching ratio of 3.5 to prepare the extruded PET diffusion film with a thickness of 350um. A 30nm thick Al2O3 barrier layer is deposited on the surface of the extruded PET diffusion film using ALD technology to obtain an extruded PET diffusion film with a barrier layer, and its structure is as follows: Figure 1 As shown, the barrier layer (5), the first PET optical layer (6), the diffusion function layer (7), and the second PET optical layer (8) are sequentially stacked from one side to the other side of the extruded PET diffusion film with a barrier layer.

[0075] The water vapor permeability of the barrier layer prepared above is 10 -1 g / m2 / 24h, oxygen permeability is 10g / m 2 / 24h.

[0076] Step 2: Obtaining a quantum dot diffusion film:

[0077] The following perovskite quantum dot powder was prepared by referring to the method of the embodiment in the patent with publication number CN 114437710 A: 140g of FAPbBr3 perovskite quantum dot-coated PVDF polymer powder with a wavelength of 526nm (CN 114437710 A, Example 10), 50g of CsPb(Br / I)3 perovskite quantum dot-coated PMMA polymer powder with a wavelength of 625nm (CN114437710 A, Example 14) were mixed with 1000g of UV glue to form a UV-curable quantum dot coating liquid. The barrier layers of the two extruded PET diffusion films were placed opposite to each other, and the quantum dot coating liquid was applied between the barrier layers of the two extruded PET diffusion films through a slit coater and photocured (UV light source curing energy 1000mJ / cm 2 ) to form a quantum dot glue layer with a thickness of 70 μm, and obtain a quantum dot diffusion film with a structure such as Figure 2 As shown, the quantum dot diffusion film (1) is stacked in sequence from one side to the other side to form a first extruded PET diffusion film (13), a first barrier layer (12), a quantum dot glue layer (11), a second barrier layer (14), and a second extruded PET diffusion film (15).

[0078] The components of the UV glue include: 50g of polyurethane acrylate oligomer, 21g of di-trimethylolpropane tetraacrylate, 650g of tricyclodecane dimethanol diacrylate, 50g of isobornyl acrylate, 20g of photoinitiator 1173, and 20g of photoinitiator TPO-L.

[0079] Step 3: Obtain integrated quantum dot enhanced backlight film:

[0080] The quantum dot diffusion film and the CPP light-enhancing composite film with a PET base film are bonded together by roll-to-roll bonding using bonding glue to obtain an integrated quantum dot enhanced backlight film, marked as 1#, with a structure as shown below Figure 3 The quantum dot diffusion film (1), the bonding glue (2), the PET base film (3), and the brightness enhancement composite film (4) are sequentially stacked from one side to the other side of the integrated quantum dot enhanced backlight film.

[0081] The adhesive composition includes 179.5 g 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, 72.5 g triethylene glycol divinyl ether, 15.7 g 4-phenylthiophenyl diphenylsulfonium salt, 0.5 g Hycat TMAO-4 thermal cationic initiator (DTCS, USA), 4.4g antioxidant 1010. Under vacuum conditions, the bonding glue was obtained by non-invasive dispersion using a homogenizer.

[0082] The spectrum of the 1# sample film of the integrated quantum dot enhanced backlight film under blue light excitation is as follows Figure 4 shown.

[0083] Example 2

[0084] Step 1: Obtain an extruded PET diffusion film with a barrier layer:

[0085] Referring to the method of Example 2 in the patent with publication number CN 107132600A, optical PET raw materials are mixed with titanium dioxide diffusion particles, and then extruded into a film by three-layer co-extrusion, the extrusion temperature is 150°C, the extrusion speed is 1m / s, the longitudinal stretching is performed at a stretching ratio of 3.0, and the transverse stretching is performed at a stretching ratio of 3.5 to prepare the extruded PET diffusion film with a thickness of 350um. On the surface of the extruded PET diffusion film with a thickness of 350um, a layer of Al2O3 barrier layer with a thickness of 50nm is evaporated by PVD technology to obtain an extruded PET diffusion film with a barrier layer, the structure of which is the same as that in Example 1, and the water vapor permeability and oxygen permeability of the barrier layer are similar to those in Example 1.

[0086] Step 2: Obtaining a quantum dot diffusion film:

[0087] 2g of red CdSe quantum dots and 3g of green CdSe quantum dot powder were mixed with 1000g of UV glue to form a UV-curable quantum dot coating liquid. CdSe quantum dots were synthesized using a hot injection method (the synthesis method is referenced in the literature https: / / doi.org / 10.1007 / s12274-016-1287-3) to form a coated core-shell structure. The barrier layers of two layers of extruded PET diffusion films were placed opposite to each other, and the quantum dot coating liquid was applied between the barrier layers of the two layers of extruded PET diffusion films through a slit coater and photocured (UV light source curing energy 1000mJ / cm 2 ) to form a quantum dot glue layer with a thickness of 70 um to obtain a quantum dot diffusion film, the structure of which is the same as that in Example 1.

[0088] The components of the UV glue include: 350g aliphatic polyurethane acrylate oligomer CN8888NS, 160g (2) ethoxylated bisphenol A dimethacrylate SR348LNS, 320g aromatic polyurethane acrylic resin, 165g tricyclodecane dimethanol diacrylate, and 40g photoinitiator TPO-L.

[0089] Step 3: Obtain integrated quantum dot enhanced backlight film:

[0090] The quantum dot diffusion film and the DPP brightness enhancement composite film whose base film is a PET film are bonded together by roll-to-roll bonding using bonding glue to obtain an integrated quantum dot enhanced backlight film, which is marked as 2# and has the same structure as in Example 1.

[0091] The components of the bonding glue include: 196.7 g of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, 41.7 g of 3-ethyl-3-hydroxymethyloxetane, 14.9 g of 4,4'-bis[bis(β-hydroxyethoxy)phenylsulfonium]phenyl sulfide-bis-hexafluoroantimonate, and 1.8 g of antioxidant 1076. Under vacuum conditions, the bonding glue is obtained by non-invasive dispersion by a homogenizer.

[0092] The spectrum of the 2# sample film of the integrated quantum dot enhanced backlight film under blue light excitation is as follows Figure 5 shown.

[0093] Comparative Example 1

[0094] The preparation method of the integrated quantum dot enhanced backlight film is the same as that in Example 1, except that no barrier layer is made on both sides of the extruded PET diffusion film, which is used to evaluate the stability of QDs in the integrated quantum dot enhanced backlight film without a barrier film. The obtained barrier-free integrated quantum dot backlight film is marked as 3#.

[0095] Comparative Example 2

[0096] The preparation method of the integrated quantum dot enhanced backlight film is the same as that of Example 1, except that step S3 is omitted and the integrated quantum dot enhanced backlight film is no longer obtained to evaluate the stability of the quantum dot extruded diffusion film. The obtained quantum dot diffusion film is marked as 4#.

[0097] Test Case

[0098] The membrane samples 1# to 4# of Examples 1 and 2 and Comparative Examples 1 and 2 were cut into 60 mm*60 mm pieces and tested as follows:

[0099] Luminous efficiency test: Quantum dot luminous efficiency (PCE) is used to characterize the efficiency of quantum dots in absorbing blue light and converting it into red and green light. The higher the PCE value, the higher the efficiency of the diaphragm in converting blue backlight. At the same time, the brightness of the backlight module is also higher.

[0100] Reliability test: test the samples for 1000h under two accelerated aging conditions: a. high temperature blue light irradiation (50℃ temperature, 80% RH humidity, 150W / m2 blue light irradiation) and b. high temperature and high humidity (60℃ temperature, 90% RH humidity). Detect the brightness attenuation, CIE x color point drift and CIE y color point drift before and after aging. Repeat three sets of tests and take the average value. The smaller the brightness and color point drift, the longer the service life of the film.

[0101] The test results are shown in Table 1. The PCE of samples 1# to 3# is not much different from that of sample 4#, indicating that the optical performance of the quantum dot diffusion film and the brightness enhancement composite film remains almost unchanged when used together or separately.

[0102] After aging for 1000h under two conditions Ab, the brightness attenuation of samples 1#~2# is <10%, and the CIE x and CIE y color point drift is <10‰. The brightness attenuation of sample 3# is >50%, and the CIE x and CIE y color point drift is >30‰. The brightness attenuation of sample 4# is <10%, and the y color point drift is <10‰, indicating that the integrated quantum dot enhanced backlight film has stable aging resistance, and the stability is still maintained compared with the quantum dot diffusion film itself. Sample 3# without a barrier layer has very poor aging resistance and cannot meet the customer's application requirements, indicating that the protection of QDs mainly comes from the barrier functional layer.

[0103] Table 1 Test data comparison

[0104]

[0105]

[0106] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An integrated quantum dot enhanced backlight film, It is characterized in that including a quantum dot diffuser film; The quantum dot diffusion film comprises a quantum dot glue layer and a composite functional layer symmetrically arranged on both sides of the quantum dot glue layer; The side of the composite functional layer facing the quantum dot glue layer is a barrier layer, and the other side is an extruded PET diffusion film layer; A brightness enhancement composite film is laminated on at least one side of the quantum dot diffusion film.

2. The integrated quantum dot enhanced backlight film according to claim 1, It is characterized in that The brightness enhancement composite film is composited on the surface of the quantum dot diffusion film by bonding glue; The side of the brightness enhancement composite film facing the quantum dot adhesive layer is a PET base film layer.

3. The integrated quantum dot enhanced backlight film according to claim 1, It is characterized in that The barrier layer is a metal oxide layer deposited on an extruded PET diffusion film layer; Preferably, the thickness of the barrier film is 10 nm to 1000 nm; Preferably, the water vapor barrier rate of the barrier film is>10 -1 g / m 2 / sky; Preferably, the oxygen barrier rate of the barrier film is>10 -1 cm 3 / m 2 / sky.

4. The integrated quantum dot enhanced backlight film according to claim 1, It is characterized in that The extruded PET diffusion film layer comprises a diffusion function layer and two PET optical layers symmetrically arranged on both sides of the diffusion function layer; The diffusion function layer is a PET film layer containing diffusion particles; Preferably, the thickness of the extruded PET diffusion film is 50 μm to 500 μm; Preferably, the haze of the extruded PET diffusion film is 10%-99%; Preferably, the transmittance of the extruded PET diffusion membrane is 30%-90%.

5. The integrated quantum dot enhanced backlight film according to claim 1, It is characterized in that The quantum dot glue layer includes a cured UV-curable glue matrix and quantum dot powder particles and quantum dot diffusion particle particles dispersed inside; Preferably, the quantum dot powder particles are selected from at least one of quantum dot particles and composite particles of quantum dots and polymers or inorganic oxides; Preferably, the material of the quantum dot diffusion particles is selected from at least one of titanium dioxide, silicon dioxide and zirconium oxide; Preferably, the thickness of the quantum dot glue layer is 30-150 μm.

6. The method for preparing the integrated quantum dot enhanced backlight film according to any one of claims 1 to 5, It is characterized in that The steps include: S1, obtaining an extruded PET diffusion film and a quantum dot coating liquid; S2, depositing a barrier layer on one side of the extruded PET diffusion film to obtain a composite functional layer; S3, making one side of the barrier layer on the two composite functional layers face each other, coating the quantum dot coating liquid between the barrier films on both sides, and curing to obtain an integrated quantum dot diffusion film; S4, compounding at least one side of the quantum dot diffusion film and the brightness enhancement composite film by bonding glue to obtain the integrated quantum dot enhanced backlight film.

7. The preparation method according to claim 6, It is characterized in that In step S1, the method for preparing the extruded PET diffusion membrane comprises the following steps: After mixing the optical PET raw material with the diffusion particles, the mixture is extruded into a film by three-layer co-extrusion, and then four-way stretching is performed to obtain the extruded PET diffusion film; Preferably, the diffusion particle raw material is selected from at least one of silicon dioxide, titanium dioxide, barium sulfate, organic silicon or calcium carbonate; Preferably, the conditions for the three-layer co-extrusion include: a temperature of 100°C to 200°C, an extrusion speed of 0.5 to 5 m / s; Preferably, the four-way stretching conditions include: longitudinal stretching at a stretching ratio of 3.0 to 3.5, and transverse stretching at a stretching ratio of 3.5 to 4.

8. The preparation method according to claim 6, It is characterized in that In step S1, the quantum dot coating liquid includes UV curing glue and quantum dot powder particles dispersed in the UV curing glue; Preferably, in step S2, the deposition method is selected from at least one of physical vapor deposition, chemical vapor deposition, and atomic layer deposition.

9. The preparation method according to claim 6, It is characterized in that In step S4, the composite method is roll-to-roll lamination; The side of the brightness enhancement composite film facing the quantum dot adhesive layer is a PET base film layer.

10. Use of the integrated quantum dot enhanced backlight film according to any one of claims 1 to 5 or the integrated quantum dot enhanced backlight film obtained by the preparation method according to any one of claims 6 to 9 in a backlight module of a liquid crystal display.

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