KR102063670B1 - Fiberous-web structure type quantumdot sheet for BLU, Manufacturing method thereof and Back light unit containing the same - Google Patents

Abstract

The present invention relates to a quantum dot sheet having a fibrous-web structure, a method of manufacturing the same, and a backlight unit (BLU) having the same. The quantum dot sheet of the present invention includes a quantum dot layer having a three-dimensional network structure formed of an aggregate of nanofibers. . According to the present invention, since the quantum dot sheet of the present invention has a three-dimensional network structure formed by a fibrous aggregate rather than a flat plate shape, the quantum dot sheet has an effect of diffusely reflecting light in structure and shape. It is possible to reduce the thickness of the composite sheet and the backlight unit that can replace two kinds of sheets with one sheet. In addition, it is possible to convert blue light to white light while using less quantum dots than conventional quantum dot sheets, and because of high color reproducibility, it is possible to provide a display and a lighting device having excellent color reproducibility, and furthermore, as a fibrous web structure, it is very flexible. Because of its superiority, it can be applied to flexible displays and flexible lighting fixtures.

Description

Fibrous-web structure type quantumdot sheet for BLU, Manufacturing method etc and Back light unit containing the same}

The present invention relates to an image display device, and more particularly, to a quantum dot sheet having a fibrous-web structure for a quantum dot display, a method of manufacturing the same, and a backlight unit including the same.

In general, the backlight unit is a light source device that emits light behind a liquid crystal display such as a liquid crystal display (LCD), and uses a LED as a light source. The backlight unit uses red (R) or green (G) fluorescent materials on a blue LED chip to emit white light when the LED is used as a light source.

Recently, a backlight unit for emitting white light using the quantum dot sheet 1d has been proposed (see FIG. 1). The white light implemented through the quantum dot sheet has an excellent color expressing ability compared to white light through a conventional blue LED chip and a fluorescent material. In this case, the production amount of the backlight unit using the quantum dot sheet is gradually increasing.

In general, a backlight unit incorporating a quantum dot sheet is disposed in a light guide plate 1, an LED light source 2 disposed on a side surface of the light guide plate 1, and a lower part of the light guide plate 1, as illustrated in FIG. 1. It is configured to emit white light, including a reflecting plate 3, a quantum dot sheet 4, a diffusion sheet 5, and a prism sheet 6 which are sequentially stacked on the light guide plate 1.

For example, when the LED light source 1b is a blue LED, a quantum dot sheet 4 including a quantum dot capable of emitting red (R) and green (G) is used. Referring to FIG. 2, the quantum dot sheet 4 includes a quantum dot layer 4a in which quantum dots are distributed and a barrier layer 4b covering upper and lower surfaces of the quantum dot layer 4a. The barrier layer 4b blocks moisture and air from entering the quantum dot layer 4a. The quantum dot sheet 4 is formed by bonding the barrier layer 4b to the upper and lower surfaces of the quantum dot layer 4a, respectively. The structure has a separate adhesive layer 4c between the quantum dot layer 4a and the barrier layer 4b. The adhesive layer 4c lowers the light transmittance and the light efficiency, and the manufacturing process is complicated, which acts as a factor of increasing the manufacturing cost.

In the quantum dot sheet 4, the quantum dot layer 4a is formed, and then the quantum dot layer 4a is in contact with air in the process of bonding the barrier layer 4b to the upper and lower surfaces of the quantum dot layer 4a, respectively. Oxidation and thickening of the quantum dot layer made it difficult to thin, which acted as a factor in increasing the volume and / or thickness of the backlight unit.

In addition, in the conventional quantum dot sheet 4, the quantum dots may be entangled or aggregated in the quantum dot layer 4a, thereby deteriorating the inherent characteristics of the quantum dots and frequently causing defects in which uniform light emission is not achieved. It was necessary to include a larger amount of quantum dots in the layer 4a than the quantum dots of the necessary reference value, which causes an increase in the manufacturing cost of the quantum dot sheet.

Accordingly, there is an urgent need for the development of a new quantum dot sheet capable of reducing thickness while having excellent color reproducibility due to high efficiency of changing white light with respect to blue light.

KR 2012-0091441 A KR 2014-0139680 A

The present invention has been made in view of the above, and the nanofibers including the quantum dots are formed in the form of a web having a three-dimensional network structure, and the phosphor contained inside the three-dimensional network structure, a small amount of quantum dots The purpose of the present invention is to provide a quantum dot sheet having a fibrous-web structure that can implement white light and replace the diffusion sheet (or diffusion film) in the backlight unit configuration.

It is another object of the present invention to provide a method for producing the fibrous-web structured quantum dot sheet with high productivity.

Another object of the present invention is to provide a BLU having a reduced thickness by introducing the quantum dot sheet and removing the diffusion sheet (or diffusion film).

In addition, another object of the present invention is to provide a liquid crystal display (LCD), a light emitting diode (LED) display, and a light emitting diode (LED) lighting device having excellent color reproduction power using the BLU.

In order to solve the above problems, the present invention includes a quantum dot layer having a three-dimensional network structure formed of an aggregate of nanofibers, wherein the nanofiber includes a quantum dot, a fibrous web including a phosphor inside the three-dimensional network structure ( Web) provides a quantum dot sheet of the structure.

According to a preferred embodiment of the present invention, the quantum dot sheet of the fibrous web structure may be formed of a single layer structure of the quantum dot layer.

In addition, the quantum dot sheet of the fibrous web structure may further include a support layer or a barrier layer under the quantum dot layer when viewed in the light transmission direction.

In addition, the quantum dot sheet of the fibrous web structure may further include a barrier layer on the quantum dot layer when viewed in the light transmission direction.

In addition, the quantum dot sheet is a quantum dot; Phosphor; And a polymer resin; wherein the nanofibers may include 0.5 to 5 parts by weight of the quantum dots, based on 100 parts by weight of the polymer resin.

In addition, the quantum dot layer may be prepared to have a three-dimensional network structure by forming an aggregate of nanofibers by electrospinning or electrospraying a mixed solution containing a quantum dot dispersion solution, a phosphor and a polymer resin.

In addition, the quantum dot is PL (photoluminescence) wavelength peak (peak) of the red-based quantum dot 600 nm ~ 750 nm; Yellow quantum dots having a PL wavelength peak of 550 nm to 600 nm; And a green quantum dot having a PL wavelength peak of 490 nm to 530 nm. It may include one or more selected quantum dots.

In addition, the phosphor may include one or more selected from silicate-based phosphors, sulfide-based phosphors, oxynitride-based phosphors, nitride-based phosphors, and aluminate-based phosphors.

The quantum dot layer may include 10 to 20 parts by weight of the phosphor based on 100 parts by weight of the polymer resin.

The quantum dot layer may include the red quantum dots and the green phosphor in a weight ratio of 1:10 to 40.

In addition, the nanofibers of the quantum dot layer may be coated with a barrier material.

In addition, the barrier layer may be formed by spray coating or spin coating on the quantum dot layer.

In addition, the barrier layer in the form of a support layer and a sheet, film or coating layer may comprise the same resin as the polymer resin constituting the quantum dot layer.

The quantum dot has an average particle diameter of 1 nm to 50 nm, the phosphor has an average particle diameter of 2,000 nm to 30,000 nm, the nanofiber has an average particle diameter of 200 nm to 1,000 nm, and the average thickness of the quantum dot layer is 50 μm to 100 μm. Can be.

영역에 대한 색좌표 측정시, CIE x 값 및 CIE y 값이 하기 방정식 1 및 방정식 2의 색좌표 값을 만족할 수 있다.In addition, the quantum dot sheet of the present invention is 1.5mm of the quantum dot sheet using a color coordinate measuring apparatus under the conditions of 0.5m distance between the blue light source and the quantum dot sheet and the measurement angle of 0.2 °

In the color coordinate measurement for the region, the CIE x value and the CIE y value may satisfy the color coordinate values of Equations 1 and 2 below.

Equation 1

0.25 ≤ CIE x ≤ 0.35

[Equation 2]

0.30 ≤ CIE y ≤ 0.40

In addition, the quantum dot sheet of the fibrous web structure may have a color reproducibility of 100% or more when viewed in the NTSC 100% color gamut based on the CIE 1931 color coordinates, and may have a luminance of 4,600 cd / m ² or more.

According to another aspect of the present invention, a method of preparing a quantum dot sheet having a fibrous web structure includes preparing a mixed solution including a quantum dot dispersion solution including a quantum dot, a phosphor, a polymer resin, and a solvent; Performing a step of electrospinning or electrospraying the mixed solution on an upper surface of the support layer or the barrier layer to form an aggregate in which nanofibers are stacked; And three steps of manufacturing a quantum dot layer having a three-dimensional network structure by drying the aggregate on which the nanofibers are stacked, including a phosphor in the three-dimensional network structure, and including the quantum dots in the nanofibers.

In addition, the method of manufacturing the quantum dot sheet may further include a four-step lamination layer on the quantum dot layer.

The method may further include separating the quantum dot layer of the three steps from the support layer or the barrier layer.

In addition, the present invention provides a backlight unit including a quantum dot sheet of the fibrous web structure of the various forms described above.

In addition, the backlight unit may not include a separate diffusion sheet (or diffusion film) as a component, and may include a light guide plate, the quantum dot sheet, and a prism sheet.

The quantum dot sheet and the prism sheet may be sequentially stacked on the top surface of the light guide plate.

In addition, the light guide plate may further include a reflecting plate disposed on the bottom surface.

In addition, the present invention provides a light emitting diode (LED) including the quantum dot sheet of the fibrous web structure of the various forms described above.

In addition, the present invention can provide a display such as a liquid crystal display (LCD), a light emitting diode (LED) including the backlight unit.

The quantum dot sheet according to the present invention is a web-like quantum dot sheet having a three-dimensional network structure in which a fibrous aggregate that is not in the form of a flat plate has an effect of diffusely reflecting light in its structure and shape, thereby replacing and / or dispersing the diffusion sheet. By eliminating the application of diffusion sheet in manufacturing BLU, it is possible to reduce the volume and / or thickness of BLU, to reduce the problem of uniform dispersion and quantum dot deterioration of quantum dots, and to pass the BLU while using less quantum dots than conventional quantum dot sheet. White light can be emitted and high color reproducibility can be realized.

Furthermore, the quantum dot sheet of the present invention is a fibrous web structure, and thus can be applied to a flexible display, a flexible lighting device, etc. because of its excellent flexibility.

1 is a schematic cross-sectional view of a backlight unit incorporating a conventional quantum dot sheet;
2 is a schematic cross-sectional view of a conventional quantum dot sheet,
3 is a cross-sectional view schematically showing a quantum dot sheet according to an embodiment of the present invention;
4 is a schematic enlarged view of a nanofiber forming a three-dimensional network structure in a quantum dot sheet;
5 is a cross-sectional view schematically showing a quantum dot sheet according to another embodiment of the present invention;
6 is a cross-sectional view schematically showing a quantum dot sheet according to another embodiment of the present invention;
7 is a schematic cross-sectional view of a backlight unit incorporating a quantum dot sheet of the present invention, and
8 shows a CIE 1931 color coordinate system.

As used herein, the term "layer" or "sheet" is intended to include all sheet, film, or plate forms unless otherwise stated.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

Referring to FIG. 3, in the quantum dot sheet 100 according to the exemplary embodiment of the present invention, an aggregate of nanofibers forms a three-dimensional network structure.

And, referring to Figure 4, the nanofibers constituting the quantum dot sheet 100 includes a quantum dot 15, and includes a phosphor 13 in the three-dimensional network structure formed by the nanofiber aggregate, nanofibers The phosphor is fixed by the aggregate, and the phosphor is arranged inside the three-dimensional network structure.

The quantum dot sheet of the present invention has a fibrous web structure having a three-dimensional network structure, and can uniformly disperse quantum dots and phosphors, and additionally introduce a phosphor in addition to the quantum dots to prevent or reduce deterioration of quantum dots due to oxygen and moisture. In this case, the amount of quantum dots can be reduced, thereby reducing costs.

Referring to FIG. 5, the quantum dot sheet 100 may be configured in a form in which the quantum dot layer 11 is laminated on the upper surface of the support layer 17 or the barrier layer when viewed in the light transmission (or traveling) direction. Alternatively, the quantum dot sheet of the present invention may be peeled off from the support layer or barrier layer to form a quantum dot sheet using only the quantum dot layer itself (see FIG. 3). In the quantum dot layer, when viewed from the top, nanofibers may be densely formed so that there are no voids.

In addition, referring to FIG. 6, in order to prevent oxidation of the quantum dots in the nanofibers, the barrier layer 19 may be stacked on the upper and / or lower portions of the quantum dot layer 11 to form the quantum dot sheet 100. Coating of the surface of the nanofibers constituting the quantum dot layer with a barrier material may prevent oxidation of the quantum dots.

When light passes through the quantum dot sheet 100, since the light is diffusely reflected by the nanofibers constituting the quantum dot sheet has a light diffusion effect, since the quantum dot sheet can act as a diffusion sheet, it is shown in the schematic diagram in FIG. As such, it is possible to provide a BLU that omits the use of a diffusion sheet. That is, the BLU in which the quantum dot sheet and the prism sheet are sequentially stacked on the upper surface of the light guide plate may be provided. In addition, a reflector may be disposed on the bottom surface of the light guide plate of the BLU.

The present invention will be described in more detail through the description of the method of manufacturing the quantum dot sheet.

The quantum dot sheet of the present invention comprises the steps of preparing a mixed solution containing a quantum dot dispersion solution containing a quantum dot, a phosphor, a polymer resin and a solvent; Performing a step of electrospinning or electrospraying the mixed solution to form an aggregate in which nanofibers are stacked; And manufacturing a quantum dot layer having a three-dimensional network structure by drying the aggregate on which the nanofibers are stacked.

The quantum dot of the quantum dot dispersion solution is a particle in which the nano-sized II-IV semiconductor particles form a core, and the fluorescence of the quantum dot is generated when the electrons in the excited state fall from the conduction band to the valence band. It is light. In the present invention, the quantum dot is PL (photoluminescence) wavelength peak (peak) of the red-based quantum dot 600 nm ~ 750 nm; Yellow quantum dots with a PL wavelength peak of 550 nm to 600 nm; And a green quantum dot having a PL wavelength peak of 490 nm to 530 nm. One or more selected from among them, preferably two or more.

In addition, general quantum dots used in the art of the quantum dots can be used, and the kind thereof will be described in detail, as group II-VI, III-V, IV-VI, group IV semiconductor, in the present invention the quantum dots Silver, Si, Ge, Sn, Se, Te, B, C, P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP , AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, Cd _x Se _y S _z , CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuInS ₂ , Cu ₂ SnS ₃ , CuBr, CuI, Si ₃ N ₄ , Ge ₃ N ₄ , Al ₂ O ₃ , (Al, Ga, In) ₂ (S, Se, Te) ₃ , CIGS, CGS and (ZnS) _y (Cu _x Sn _{1 - x} S ₂ ) _1-y , where x is 0 <x <1 , y is a rational number satisfying 0 <y <1). In addition, the quantum dot may have a core / shell structure or an alloy structure, and non-limiting examples of the quantum dot having the core / shell structure or the alloy structure may include CdSe / ZnS, CdSe / ZnSe / ZnS, and CdSe / CdSx (Zn1). -yCdy) S / ZnS, CdSe / CdS / ZnCdS / ZnS, InP / ZnS, InP / Ga / ZnS, InP / ZnSe / ZnS, PbSe / PbS, CdSe / CdS, CdSe / CdS / ZnS, CdTe / CdS, CdTe / ZnS, CuInS ₂ , / ZnS, Cu ₂ SnS ₃ / ZnS, and the like. The specific examples of the quantum dots are described to help the understanding of the present invention, and the present invention is not limited by the types of the quantum dots.

In addition, the quantum dots are those having an average particle diameter of 1 nm to 50 nm, preferably those of 2 nm to 30 nm, more preferably 2 nm to 20 nm, wherein the average particle diameter of the quantum dots is 50 If the thickness exceeds nm, the quantum dots deviating from the nanofibers during electrospinning or electrospinning may increase, so that a quantum dot having an average particle diameter within the above range is used.

As a specific example, the red quantum dots are CdSe having an average particle diameter of 5.2 nm to 8 nm, and the green quantum dots are CdSe having an average particle diameter of 3 nm to 4.5 nm, and these may be mixed and used.

As yet another specific example, the quantum dot is a red based CuInS ₂ having an average particle size of ~ 4.5㎚ 5.2㎚, yellow-based quantum dot is CuInS ₂ having an average particle size of ~ 2.5㎚ 4.0㎚, can use them by mixing

The quantum dot dispersion solution includes a solvent that can be evenly dispersed. For example, the solvent of the quantum dot dispersion solution is toluene, formamide, dimethyl sulfoxide, dimethylformamide, acetic acid, acetonitrile, methoxy ethanol, tetra It may include one or two selected from hydrofuran, benzene, xylene, cyclohexane, methanol, chloroform and acetone.

The amount of the quantum dots in the mixed solution may be 0.5 to 5 parts by weight, preferably 0.8 to 3 parts by weight, based on 100 parts by weight of the polymer resin. In this case, when the amount of the quantum dot is less than 0.5 parts by weight, there is a problem in that the amount of the phosphor is used to implement white light, color reproducibility may be reduced, and the use of more than 5 parts by weight is uneconomical. It is good to use.

The phosphor may be a common phosphor used in the art, preferably one or two or more selected from a silicate phosphor, a sulfide phosphor, an oxynitride phosphor, a nitride phosphor, and an aluminate phosphor. Can be.

In one example, the phosphor is (Sr, Ca) B ₄ O ₇ : Eu, BaMgAl ₁₀ O ₁₇ : Eu, Y ₂ O ₃ : Eu, InBO ₃ : Eu, YVO ₄ : Eu, YBO ₃ : Eu, (Y, Gd) BO ₃ : Eu, SrTiO ₃ : Eu, (Si, Al) ₆ (O, N) ₈ : Eu, Y ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, (La, Mn, Sm) ₂ O ₂ SGa ₂ O ₃ : Eu, (Ca, Sr) S: Eu, CaAlSiN ₃ : Eu, (Sr, Ca) AlSiN ₃ : Eu, Sr ₂ Si ₅ N ₈ : Eu, CaGa ₂ S ₄ : Eu, SrGa ₂ S ₄ : Eu, SrSi ₂ O ₂ N ₂ : Eu, BaGa ₂ S ₄ : Eu, SrAl ₂ O ₄ : Eu, BAM: Eu, (Ba, Sr, Ca) ₂ SiO ₄ : Eu, ( Sr, Ba, Ca, Mg, Zn) ₂ Si (OD) ₄ : Eu, where D is F, Cl, S, N or Br, β-SiAlON: Eu, Ba ₃ Si ₆ O ₁₂ N ₂ : Eu, Ba ₂ MgSi ₂ O ₇ : Eu, Mg ₂ SiO ₄ : Mn, Zn ₃ (PO ₄ ) ₂ : Mn, (Y, Gd) BO ₃ : Tb, Ca ₃ (Sc, Mg) ₂ Si ₃ O ₁₂ : Ce, Y ₂ SiO ₅ : Ce, Ca ₃ Y ₂ Si ₆ O ₈ : Ce, BaAl ₁₂ O ₁₉ : Mn, Y ₃ Al ₅ O ₁₂ : Ce, Y ₃ Al ₅ O ₁₂ : Tb, Zn ₂ SiO ₄ One kind or two or more kinds selected from: Mn, InBO ₃ : Tb, ZnS: Cu, and Ca ₁₀ (PO ₄ ) ₆ Cl ₂ can be used. Preferably, the red phosphor is Y ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, (La, Mn, Sm) ₂ O ₂ S.Ga ₂ O ₃ : Eu, (Ca, Sr) S : Eu, CaAlSiN ₃ : Eu, (Sr, Ca) AlSiN ₃ : Eu and Sr ₂ Si ₅ N ₈ : Eu may include at least one selected from the phosphor, and the green phosphor is CaGa ₂ S ₄ : Eu. , SrGa ₂ S ₄ : Eu, SrSi ₂ O ₂ N ₂ : Eu, BaGa ₂ S ₄ : Eu, SrAl ₂ O ₄ : Eu, BAM: Eu, (Ba, Sr, Ca) ₂ SiO ₄ : Eu, (Sr , Ba, Ca, Mg, Zn) ₂ Si (OD) ₄ : Eu, where D is F, Cl, S, N, or Br, β-SiAlON: Eu, Ba ₃ Si ₆ O ₁₂ N ₂ : It may include one or more selected from Eu, Ba ₂ MgSi ₂ O ₇ : Eu and Ca ₃ (Sc, Mg) ₂ Si ₃ O ₁₂ : Ce.

In addition, it is preferable that the phosphor has an average particle diameter of 2,000 nm to 30,000 nm, preferably 5,000 nm to 25,000 nm, and more preferably 6,000 nm to 16,000 nm, wherein the average particle diameter of the phosphor is 30,000. When it exceeds nm, since the particle diameter is too large and it is difficult to be fixed by the nanofibers after electrospinning or electrospray, a phosphor may be separated from the quantum dot layer. Therefore, it is preferable to use a phosphor having an average particle diameter within the above range.

In this case, the amount of the phosphor may be used in an amount of 10 to 20 parts by weight, preferably 12 to 18 parts by weight, based on 100 parts by weight of the polymer resin. In this case, when the amount of the phosphor is less than 10 parts by weight, the wavelength for realizing white light is increased. There may be a problem, and when used in excess of 20 parts by weight, the dispersibility is lowered, which may be a problem of non-uniform emission of white light.

In addition, the quantum dots and the phosphor are used in a ratio of 1:10 to 40 by weight, preferably 1:10 to 25 by weight, and more preferably 1:12 to 20 by weight, in terms of securing high color reproducibility. Do. For example, the quantum dot may use the red quantum dot, and the phosphor may use one or more selected from the green phosphor and the yellow phosphor.

Alternatively, the quantum dot may use one or more selected from green quantum dots and yellow quantum dots, and the phosphor may use the red phosphor.

In the first step, the polymer resin is polyethylene terephthalate resin, polycarbonate resin, polyalkylmethacrylate resin, polymethacrylate resin, polyvinylidene fluoride ) Resins, polystyrene resins, polyvinyl chloride resins, styrene acrylonitrile copolymer resins, polyurethane resins, polyamide resins, polyvinyl butyral One or a combination of two or more selected from among polyvinyl butyral, silicone resin, polyvinyl acetate resin, and unsaturated polyester resin may be used. Excellent polyethylene terephthalate resin, polycarbonate The root resin, a polyalkyl methacrylate resin and polyvinylidene fluoride, one selected from resin either alone or in combination of two or more may be mixed. For example, polyalkyl methacrylate resin and polyvinylidene fluoride resin can be mixed and used in 5-7: 3-5 weight ratio.

The solvent of the first stage mixed solution is a solvent capable of dissolving the polymer resin, and may be a general one used in the art, and the amount of the solvent used may be 500 to 20,000 parts by weight, preferably 600, based on 100 parts by weight of the polymer resin. It is preferable to use ˜5,000 parts by weight, more preferably 650 to 1,500 parts by weight in view of maintaining the proper viscosity for electrospinning or electrospray of the mixed solution, the solvent of the mixed solution is dimethyl sulfoxide, dimethylformamide, dimethyl Acetamide, acetone, toluene, formamide, acetic acid, acetonitrile, methoxy ethanol, tetrahydrofuran, benzene, xylene, and cyclohexane may be used alone or in combination of two or more thereof.

Step 2 is a step of forming an aggregate of nanofibers and nanofibers by electrospinning or electrospraying the mixed solution prepared in step 1, when the mixed solution is high concentration (high viscosity), it is preferable to perform electrospinning, mixing When the solution is low in concentration (low viscosity), it is preferable to perform electrospray to form nanofibers and aggregates of nanofibers.

In the second step, the mixed solution may be electrospun or electrosprayed on the upper surface of the support layer or the barrier layer to form a two-layer structure (support layer-quantum dot layer or barrier layer-quantum dot layer). At this time, the support layer or barrier layer is polyethylene terephthalate resin, polycarbonate resin, polyalkyl methacrylate resin, polymethacrylate resin, polyvinylidene fluoride resin, polystyrene resin, polyvinyl chloride resin, styrene acrylonitrile One kind or a mixture of two or more kinds selected from reel copolymer resins, polyurethane resins, polyamide resins, polyvinyl butyral resins, silicone resins, polyvinylacetate resins, and unsaturated polyester resins may be used. Prepared using a polymer resin having one or more selected from polyethylene terephthalate resin, polycarbonate resin, polyalkyl methacrylate resin, polymethacrylate resin and polyvinylidene fluoride resin having excellent transparency. Available In the case where the quantum dot sheet has a two-layer structure or more, it is possible to improve the bonding strength with the quantum dot layer by using the same polymer resin as that of the mixed solution.

Electrospinning or electrospraying in two steps is carried out so that the nanofibers have an average particle diameter of 200 nm to 1,000 nm, preferably 200 nm to 800 nm, more preferably 250 nm to 600 nm, wherein the average particle diameter of the nanofibers is If it is too small at 200 nm, there may be a problem of shape stability and quantum dot protrusion, and if it is more than 1,000 nm, there may be a problem in that the diffuse reflection effect of light is reduced.

In addition, the barrier material may be spin-coated or spray coated on the surface of the nanofibers formed by the electrospinning or electrospraying in step 2 to form an aggregate in which the nanofibers having the barrier coating layer are stacked.

Step 3 is a step of forming a quantum dot layer having a three-dimensional network structure by drying the aggregate in which the nanofibers are laminated in step 2, wherein the quantum dot layer has an average thickness of 50 ㎛ ~ 100 ㎛, preferably 60 ㎛ ~ 100 ㎛, More preferably, it can form in 60 micrometers-90 micrometers.

In addition, the drying is to remove the residual solvent and to further form a junction between the nanofibers and the nanofibers, and the drying temperature may vary depending on the type of the solvent and the polymer resin, but may be 30 ° C. to 60 ° C. It is preferable to perform drying by a method such as hot air drying by applying heat of ° C.

In addition, the method of manufacturing the quantum dot sheet may be prepared by performing a process further comprising a step; laminating a barrier layer on top of the quantum dot layer.

Here, the resin used to form the barrier layer in the fourth step may be prepared by using one polymer selected from polycarbonate resins, polymethacrylate resins, and polyvinylidene fluoride resins alone or in a mixture of two or more thereof. It is preferable to use the same polymer resin of the first step in terms of improving the bonding strength between the quantum dot layer and the barrier film (or coating layer).

In addition, by performing a step of separating the quantum dot layer from the support layer formed on the lower portion of the quantum dot layer after the step 3 or after the step 4, the quantum dot sheet having a single layer structure consisting of only a quantum dot layer of the form as shown in FIG. It may also be made of a quantum dot sheet of a two-layer structure in which a barrier layer is laminated on or below the quantum dot layer.

영역에 대한 색좌표 측정시(도 8의 CIE 1931 색좌표 참조), CIE x 값 및 CIE y 값이 하기 방정식 1 및 방정식 2의 색좌표 값을 만족할 수 있다.The quantum dot sheet of the present invention having such a fibrous web structure is 1.5mm of the quantum dot sheet using a color coordinate measuring apparatus under conditions of a distance of 0.5 m and a measurement angle of 0.2 ° between the blue light source and the quantum dot sheet.

When measuring color coordinates for an area (see CIE 1931 color coordinates of FIG. 8), CIE x values and CIE y values may satisfy color coordinate values of Equations 1 and 2 below.

 Equation 1

0.23 <CIE x <0.37, preferably 0.25 <CIE x <0.35, more preferably 0.26 <CIE x <0.32

 [Equation 2]

0.28 <CIE y <0.42, preferably 0.30 <CIE y <0.40, more preferably 0.30 <CIE y <0.37

In addition, the quantum dot sheet of the present invention has excellent color reproducibility since it has a high color reproducibility of 100% or more, preferably 102% or more, more preferably 103% or more when viewed in the NTSC 100% color gamut based on the CIE 1931 color coordinate. You can have

In addition, the quantum dot sheet of the present invention may have a high luminance of 4,600 cd / m ² or more, preferably 4,800 cd / m ² or more, and more preferably 4,850 cd / m ² to 5,500 cd / m ² .

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are provided to aid the understanding of the present invention and should not be construed as limiting the scope of the present invention by the following examples.

[ Example ]

Preparation  1-1: Red system Quantum dots  Preparation of Dispersion Solution

A quantum dot dispersion solution in which CdSe having an average particle diameter of 6 nm having a PL wavelength peak of 650 to 660 nm was dispersed in a toluene solvent was prepared.

Preparation  1-2: Red system Quantum dots  Preparation of Dispersion Solution

A quantum dot dispersion solution in which CuInS ₂ with an average particle diameter of 4.8 to 5.0 nm having a PL wavelength peak of 695 to 710 nm was dispersed in an acetone solvent was prepared.

Preparation  2 : Green system Quantum dots  Preparation of Dispersion Solution

A quantum dot dispersion solution in which CdSe having an average particle diameter of 4 nm having a PL wavelength peak of 505 to 510 nm was dispersed in a toluene solvent was prepared.

Preparation  2-2: Yellow Quantum dots  Ready

A quantum dot dispersion solution in which CuInS ₂ with an average particle diameter of 2.8 to 3.0 nm having a PL wavelength peak of 550 to 560 nm was dispersed in an acetone solvent was prepared.

Preparation  3: Green system  Preparation of Phosphors

Ba ₂ MgSi ₂ O ₇ : Eu phosphor powder having an average particle diameter of 8,215 nm was prepared.

Example  One

Polymer resin comprising polyvinylidene fluoride (PVDF) resin and polymethyl methacrylate (PMMA) resin in a 6: 4 weight ratio, quantum dot dispersion solution of Preparation Example 1-1, phosphor of Preparation Example 3, and dimethylacetic as a solvent Amide was mixed and stirred to prepare a mixed solution.

At this time, the mixing ratio was 1 part by weight of the red quantum dots, 15 parts by weight of the green phosphor, and 960 parts by weight of the solvent based on 100 parts by weight of the polymer resin.

The mixed solution was electrospun on a PET film as a support, followed by hot air drying at 45 ° C. to 48 ° C. to form a quantum dot layer having an average thickness of 72 to 73 μm.

Next, a quantum dot sheet having a fibrous web structure having a single layer structure having a form as shown in FIGS. 3 and 4 was prepared by peeling the quantum dot layer from a PET film as a support.

At this time, the average particle diameter of the nanofibers constituting the quantum dot layer constituting the quantum dot sheet was 295 nm to 300 nm.

Experimental Example  One : Color coordinates , Color gamut  And luminance measurements

영역에 대한 색좌표, NTSC 100% 색영역으로 보았을 때의 색재현율 및 휘도를 측정(CIE 1931 색좌표 기준, 도 8 참조) 하였다. 그리고, 측정 결과의 정확성을 높이기 위하여 5회 분석한 후, 평균값을 계산하였고 그 결과를 하기 표 1에 나타내었다.Using the quantum dot sheet prepared in Example 1, under the conditions of 0.5 m between the blue light source (500 W intensity) and the quantum dot sheet and the measurement angle of 0.2 °, the color quantum dot sheet was measured using a color coordinate measuring apparatus (BM-7 manufactured by Topcon). 1.5mm

The color coordinates for the area, the color reproducibility and the luminance when viewed in the NTSC 100% color gamut were measured (based on CIE 1931 color coordinates, FIG. 8). And, after analyzing five times to increase the accuracy of the measurement results, the average value was calculated and the results are shown in Table 1 below.

division Color coordinates Color gamut Luminance (cd / m ² ) CIE x CIE y 1 time 0.2671 0.3088 102.5% 4,866 Episode 2 0.2680 0.3091 102.6% 4,890 3rd time 0.2689 0.3094 102.7% 4,904 4 times 0.2678 0.3093 102.5% 4,870 5th 0.2689 0.3095 102.6% 4,870 Average 0.2681 0.3092 102.6% 4,880

Referring to the experimental results of Table 1, the quantum dot sheet of the present invention composed of only the quantum dot layer of Example 1 has a color coordinate of CIE x = 0.2681 and CIE y = 0.3092, and the blue light source is converted into white light through the CIE 1931 color coordinate of FIG. I could confirm the implementation. And, it was confirmed that it has a very high color reproduction rate of 102.6%, and also it can be confirmed that it has a high luminance of 4,800 cd / m ² or more.

Example  2

Polymer resin containing polyvinylidene fluoride (PVDF) resin and polymethyl methacrylate (PMMA) resin in a 6: 4 weight ratio, the quantum dot dispersion solution of Preparation Examples 1-2, the phosphor of Preparation Example 3, and dimethylacetic as a solvent Amide was mixed and stirred to prepare a mixed solution.

At this time, the mixing ratio was 1.2 parts by weight of the red quantum dots, 15 parts by weight of the green phosphor, and 960 parts by weight of the solvent based on 100 parts by weight of the polymer resin.

The mixed solution was electrospun on a PET film as a support, and then hot-air-dried at 45 ° C to 48 ° C to form a quantum dot layer having an average thickness of 86 to 87 μm.

Next, a quantum dot sheet having a fibrous web structure having a single layer structure having a form as shown in FIGS. 3 and 4 was prepared by peeling the quantum dot layer from a PET film as a support.

At this time, the average particle diameter of the nanofibers constituting the quantum dot layer constituting the quantum dot sheet was 285 nm to 290 nm.

Example  3

To prepare a quantum dot sheet in the same manner as in Example 2, when preparing the mixed solution, 1.2 parts by weight of the red quantum dots in the red dispersion, 20 parts by weight of the green phosphor and 960 parts by weight of the solvent based on 100 parts by weight of the polymer resin. It was.

Example  4

To prepare a quantum dot sheet in the same manner as in Example 2, when preparing the mixed solution, 1.2 parts by weight of the red quantum dots in the red dispersion solution, 30 parts by weight of the green phosphor and 960 parts by weight of the solvent based on 100 parts by weight of the polymer resin. It was.

Example  5

In the same manner as in Example 2, the average thickness of the quantum dot layer was 89 ~ 90 ㎛ to prepare a quantum dot sheet having a fibrous web structure of a single layer structure. At this time, the average particle diameter of the nanofibers constituting the quantum dot layer of the quantum dot sheet was 585 nm to 595 nm.

Comparative example  One

After commacoating the mixed solution of Example 2 on a PET film as a support, it was hot-air dried at 70 ° C to 72 ° C to form a quantum dot layer in the form of a film having an average thickness of 22.6 μm.

Next, the quantum dot sheet of the sheet type was manufactured by peeling the quantum dot layer from the PET film serving as the support.

Comparative example  2

To prepare a quantum dot sheet in the same manner as in Example 2, when preparing the mixed solution, 1.2 parts by weight of the red quantum dots in the red dispersion solution, 45 parts by weight of the green phosphor and 960 parts by weight of the solvent based on 100 parts by weight of the polymer resin. It was.

Comparative example  3

To prepare a quantum dot sheet in the same manner as in Example 2, when preparing the mixed solution, 1.2 parts by weight of the red quantum dots in the red dispersion solution, 8 parts by weight of the green phosphor and 960 parts by weight of the solvent based on 100 parts by weight of the polymer resin. It was.

Comparative example  4

In the same manner as in Example 2, the average thickness of the quantum dot layer was 88 ~ 89 ㎛ to prepare a quantum dot sheet having a fibrous web structure of a single layer structure. At this time, the average particle diameter of the nanofibers constituting the quantum dot layer of the quantum dot sheet was 1,050 nm to 1,060 nm.

Experimental Example  2 : Color coordinates , Color gamut  And luminance measurements

Using the quantum dot sheets prepared in Examples 2 to 5 and Comparative Examples 1 to 4, color coordinates, color reproduction and luminance were measured in the same manner as in Experimental Example 1, and the results are shown in Table 2 below. It was. At this time, each measured value represents the average value after 5 measurements.

division Color coordinates Color gamut Luminance (cd / m ² ) CIE x CIE y Example 2 0.2959 0.3123 102.3% 4,957 Example 3 0.2955 0.3312 102.9% 4,950 Example 4 0.2956 0.3524 103.6% 4,926 Example 5 0.2962 0.3132 102.1% 4,857 Comparative Example 1 0.2894 0.3256 99.1% 4,438 Comparative Example 2 0.2961 0.3827 100.6% 4,786 Comparative Example 3 0.2967 0.2893 100.8% 4,755 Comparative Example 4 0.2952 0.3135 101.5% 4,596

Referring to the experimental results of Table 2, in Examples 2 to 5, it can be seen that the color coordinates satisfy 0.26 ≤ CIE x ≤ 0.32, 0.30 ≤ CIE y ≤ 0.37 to implement the white light, the color gamut It can be confirmed that has a. In particular, the non-cadmium-based quantum dot color reproducibility tends to be somewhat lower than the cadmium-based quantum dot, comparing the color reproducibility of Comparative Example 1 and Example 2 in the form of a coating film (or film film), the quantum dot sheet as a fibrous web By producing, it can be confirmed that there is an effect of improving the color reproducibility.

In Comparative Example 2 using the phosphor in excess of 40 weight ratio to quantum dots and Comparative Example 3 in which the phosphor was used in less than 10 weight ratio, the CIE y value exceeded 0.37, so that it was difficult to realize white light, and as a result, when compared with Example 4, Color reproducibility and luminance showed a tendency to fall.

In addition, in the case of Comparative Example 4 in which the average diameter of the nanofibers exceeded 1,000 nm, compared with Example 4, there was no significant effect on color coordinates and color reproducibility, but the luminance was greatly reduced to less than 4,600 cd / m ² . This is because the diffuse reflection effect of the light is reduced and the luminance is considered to be reduced.

Through the above examples and experimental examples, the BLU to which the quantum dot sheet of the present invention is applied can transmit high luminance light to the prism sheet without using a diffusion sheet, so that the volume (and / or thickness) without the diffusion sheet is A reduced BLU can be provided, and the BLU can be applied to a liquid crystal display device, a light emitting diode (LED) display, and a light emitting diode (LED) lighting device requiring high color reproduction. In addition, the quantum dot sheet of the present invention is a fibrous web structure, and thus can be applied to a flexible display, a flexible lighting device, etc. because of its excellent flexibility.

1: Light guide plate (or light guide sheet) 2: Light source
3: reflector 5: diffusion sheet
6: prism sheet 11: quantum dot layer
13: phosphor 15: quantum dot
17 support layer 19 barrier layer
4, 100: quantum dot sheet

Claims (20)

A quantum dot layer having an average thickness of 50 μm to 100 μm having a three-dimensional network structure formed of an aggregate of nanofibers having an average particle diameter of 200 nm to 1,000 nm,
The quantum dot layer is a three-dimensional network by forming an aggregate of electrospinning or electrospray nanofibers in a mixed solution containing a polymer resin, a quantum dot having an average particle diameter of 1 nm to 50 nm, a phosphor having an average particle diameter of 2,000 nm to 30,000 nm, and a solvent. Manufactured to have a structure,
The aggregate of the nanofibers includes the quantum dot and the phosphor in a weight ratio of 1:10 to 40,
The quantum dots include a red quantum dot having a PL (photoluminescence) wavelength peak of 600 nm to 750 nm, and the phosphor includes one or more selected from green and yellow phosphors,
The green phosphor is CaGa ₂ S ₄ : Eu, SrSi ₂ O ₂ N ₂ : Eu, BaGa ₂ S ₄ : Eu, SrAl ₂ O ₄ : Eu, BAM: Eu, (Ba, Sr, Ca) ₂ SiO ₄ : Eu, (Sr, Ba, Ca, Mg, Zn) ₂ Si (OD) ₄ : Eu (where D is F, Cl, S, N, or Br), β-SiAlON: Eu, Ba ₃ Si ₆ O ₁₂ N ₂ : Eu, Ba ₂ MgSi ₂ O ₇ : Eu and Ca ₃ (Sc, Mg) ₂ Si ₃ O ₁₂ : Ce comprising a green phosphor including at least one selected from Ce,
The quantum dot layer includes the quantum dot and the phosphor in a weight ratio of 1:10 to 25,
1.5 mm of the quantum dot sheet using a color coordinate measuring apparatus under a condition of a distance of 0.5 m and a measurement angle of 0.2 ° between the blue light source and the quantum dot sheet.

When measuring color coordinates for an area, the CIE x value and the CIE y value satisfy the color coordinate values of Equations 1 and 2 below,
A quantum dot sheet of a fibrous web structure having a color reproducibility of 102% or more and a luminance of 4,800 to 5,500 cd / m ² when viewed in NTSC 100% color gamut based on a CIE 1931 color coordinate.
Equation 1
0.25 ≤ CIE x ≤ 0.35
[Equation 2]
0.30 ≤ CIE y ≤ 0.37 The quantum dot sheet of the fibrous web structure according to claim 1, further comprising a support layer or a barrier layer under the quantum dot layer in a light transmission direction. The quantum dot sheet of a fibrous web structure according to claim 2, further comprising a barrier layer on top of the quantum dot layer in the light transmission direction. delete delete delete delete delete delete The quantum dot sheet of claim 1, wherein the nanofibers are formed by coating with a barrier material. delete delete A backlight unit comprising a quantum dot sheet of the fibrous web structure of any one of claims 1 to 3 and 10. The backlight unit of claim 13, wherein the quantum dot sheet and the prism sheet are sequentially stacked on an upper surface of the light guide plate. The backlight unit of claim 14, further comprising a reflector on a bottom surface of the light guide plate. Light emitting diode (LED) lighting device comprising a quantum dot sheet of the fibrous web structure of any one of claims 1 to 3 and 10. A liquid crystal display (LCD) comprising the backlight unit of claim 13. A light emitting diode (LED) display comprising the backlight unit of claim 13. Preparing a mixed solution containing a quantum dot dispersion solution including a quantum dot having an average particle diameter of 1 nm to 50 nm, a phosphor having an average particle diameter of 2,000 nm to 30,000 nm, a polymer resin, and a solvent;
Performing a step of electrospinning or electrospraying the mixed solution on an upper surface of the support layer or the barrier layer to form an aggregate in which nanofibers having an average particle diameter of 200 nm to 1,000 nm are stacked; And
3 steps of manufacturing a quantum dot layer having an average thickness of 50 ㎛ to 100 ㎛ having a three-dimensional network structure by drying the aggregated nanofibers;
Contains phosphors within the three-dimensional network structure, contains quantum dots in the nanofibers,
The quantum dot includes a red quantum dot having a PL (photoluminescence) wavelength peak of 600 nm to 750 nm,
The phosphor includes at least one selected from green phosphor and yellow phosphor,
The green phosphor is CaGa ₂ S ₄ : Eu, SrSi ₂ O ₂ N ₂ : Eu, BaGa ₂ S ₄ : Eu, SrAl ₂ O ₄ : Eu, BAM: Eu, (Ba, Sr, Ca) ₂ SiO ₄ : Eu, (Sr, Ba, Ca, Mg, Zn) ₂ Si (OD) ₄ : Eu (where D is F, Cl, S, N, or Br), β-SiAlON: Eu, Ba ₃ Si ₆ O ₁₂ N ₂ : Eu, Ba ₂ MgSi ₂ O ₇ : Eu and Ca ₃ (Sc, Mg) ₂ Si ₃ O ₁₂ : Ce comprising a green phosphor including at least one selected from Ce,
The quantum dot layer of the step 3 is a method for producing a fibrous web structure quantum dot sheet containing the quantum dot and the phosphor in a weight ratio of 1: 10 to 40. The method of manufacturing a fibrous web structure quantum dot sheet according to claim 19, further comprising: laminating a barrier layer on one surface of the quantum dot layer in three steps.

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