KR20160117063A - Optical sheet comprising cadmium free quantum dots - Google Patents

Abstract

The present invention relates to an optical sheet comprising non-cadmium quantum dots. According to various embodiments of the present invention, the optical sheet can exhibit excellent color purity and efficiency when applied to a display by producing the optical sheet comprising the quantum dots not using cadmium to be environmentally friendly while replacing an optical sheet including conventional cadmium-based quantum dots.

Description

An optical sheet comprising cadmium free quantum dots,

The present invention relates to an optical sheet comprising a non-cadmium-based quantum dot.

The quantum dot is a semiconductor material having a crystal structure of several nanometers in size and has different wavelengths depending on its size. As the quantum dot is used as a fluorescent material or a light emitting material, It is known that the quantum dots can be utilized by themselves. In particular, the quantum dots are formed by bonding in a small amount into a polymer optical film entering a backlight unit (BLU).

At present, the most reliable and high-performance quantum dots are cadmium-based quantum dots. Currently, the only commercially available jumjim sheet is Amazon Kindle Fire HDX 7 ", 8.9", which was developed jointly by 3M and NanoSys. There is an issue involving.

In Europe where cadmium has been identified as a hazardous substance, the use of cadmium displays by 2016 has been deferred to less than 10 g per square meter of display area, but there is a growing demand from European countries to continue the suspension.

US chemical company Dow Chemical has secured a global patent right for the manufacture and sale of cadmium-free quantum dots from Nanoko, a non-cadmium-based quantum dot developer and manufacturer. 3M is also developing quantum dot products with cadmium content of 100 ppm or less.

However, since the emission efficiency of non-cadmium-based quantum dots is lower than that of cadmium-based quantum dots, development of environmentally friendly quantum dots without cadmium having excellent luminous efficiency is required.

 Jaehoon Lim et. al., ACS Nano, 2013, 7 (10), 9019-9026.

Unlike the prior art in which cadmium-based quantum dots are environmentally harmful in the optical sheet containing quantum dots, the present invention uses a non-cadmium-based quantum dots to eliminate the risk of environmental pollution, The present invention provides an optical sheet capable of achieving high color purity and color reproducibility even if the amount of quantum dots used is reduced by patterning the layer.

In one embodiment of the present invention, a polymer resin layer in which a plurality of non-cadmium-based quantum dots are dispersed in a polymer resin and patterned on one side or both sides; A first barrier film formed on one side of the polymer resin layer; And a second barrier film formed on another side of the polymer resin layer.

The optical sheet of the present invention can replace an optical sheet including cadmium-based quantum dots in the past and is environmentally friendly.

On the other hand, in the optical sheet of the present invention, the quantum dots are dispersed and the polymer resin layer is patterned, whereby excellent color purity and color reproducibility can be exhibited even with a small quantum dot.

FIG. 1 shows an optical sheet in which a polymer resin layer in which non-cadmium-based quantum dots are dispersed is prism-patterned according to an embodiment of the present invention.
FIG. 2 illustrates a lens patterned optical sheet in a polymer resin layer in which non-cadmium-based quantum dots are dispersed according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

The optical sheet according to an embodiment of the present invention includes a polymer resin layer in which a plurality of non-cadmium-based quantum dots are dispersed in a polymer resin and patterned on one side or both sides; A first barrier film formed on one side of the polymer resin layer; And a second barrier film formed on the other surface of the polymer resin layer.

The polymer resin layer may be formed by dispersing a plurality of non-cadmium-based quantum dots in the matrix using a polymer resin as a matrix, and may have a layer structure of one or more layers.

In one embodiment of the present invention, the polymer resin used as the matrix preferably has low oxygen and moisture permeability, and also preferably has high light stability and chemical stability.

In one embodiment of the present invention, the polymeric resin may be selected from the group consisting of epoxy, epoxy acrylate, lauryl acrylate, norbornene, polyethylene, polystyrene, ethylene-styrene copolymers, bisphenol A and bisphenol A derivatives Acrylonitrile, acrylonitrile, acrylonitrile, acrylonitrile, acrylonitrile, acrylonitrile, acrylonitrile, acrylonitrile, acrylonitrile, acrylonitrile, acrylonitrile, At least one kind of polymer resin selected from the group consisting of

On the other hand, the polymer resin used may have water permeability of WVTR = 10 ^-2 g / m ² / day or less and oxygen permeability of OTR = 10 ^-2 cc / m ² / day or less.

The water vapor transmission rate (WVTR) represents the degree of water permeation through a certain material, and indicates how much moisture passes through the substrate through an area of 1 m ² per day. The measurement conditions include equipment and measurement It depends on the method. For example, MOCON Aquatron, a typical instrument, can be measured at 38 degrees and 100 percent.

Meanwhile, the OTR (Oxygen Transmission Rate) indicates how much oxygen permeates through a substance, and indicates how much oxygen passes through the substrate through an area of 1 m ² per day. The measurement standard is ASTM D-3985 . For example, it can be measured by MOCON Ox-Tran, a representative equipment.

The quantum dots refer to substantially monocrystalline nanostructures. The quantum dots may emit secondary light after absorbing primary light emitted from the light source, and may emit secondary light according to the size of the quantum dots. Light can be emitted. The quantum dot may have a typical size of 1 to 10 nm. When the quantum dot has a size of 4 to 5 nm, it may emit secondary light having a red color after absorbing the primary light from the light source. It is possible to emit secondary light having green after absorbing the primary light from the light source.

On the other hand, the quantum dots can be uniformly dispersed in the polymer matrix. When the polymer resin layer has a multi-layer structure, quantum dots having different sizes may be arranged for each layer layer, and quantum dots having different sizes may be mixed and dispersed Shape.

Meanwhile, the quantum dot according to an embodiment of the present invention is a non-cadmium quantum dot, and the quantum dots for use in the present invention may include any suitable inorganic material.

In one embodiment of the present invention, the non-cadmium-based quantum dot may comprise an inorganic material selected from the group consisting of Group II-VI, Group III-V, Group IV-VI and Group IV semiconductors.

In one embodiment of the present invention, the non-cadmium-based quantum dots include Si, Ge, Sn, Se, Te, B, C, P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, ZnSe, ZnTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, ZnSe, ZnSe, ZnSe, ZnSe, ZnSe, ZnSe, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si 3 N 4, Ge 3 N 4 and one or more kinds selected from the group consisting of a combination of And may include an inorganic material.

Meanwhile, the thickness of the polymer resin layer may be 10 to 100 mu m. When the thickness of the polymer resin layer is less than 10 탆, the quantum dots must exist at a higher density than the thick resin layer in order to satisfy a certain level of color conversion property. In this case, the interval between the quantum dots is very narrow, The degradation of efficiency caused by accelerating the degradation of the first light source or absorbing light from the first light source is expected to result in a decrease in efficiency that can be caused by the continuous absorption of the second quantum dots by the adjacent quantum dots. However, there is a problem in that the uniformity of the thickness in the coating process during production is lowered, the curl problem that may occur when winding the product, the lowering of the winding per roll, and the application of a large diameter core And the economical efficiency such as the increase of the production cost Can.

More specifically, when the thickness of the polymer resin layer is more than 100 μm, when a thin substrate having a thickness of 100 μm or less is applied, it becomes vulnerable to wrinkles due to heat generated during curing, thus requiring a thick film substrate. In this case, Is about 400um, which may cause a problem in the above-mentioned winding or actually increase the thickness of the whole mechanism when applied to the BLU.

On one side or both sides of the polymer resin layer, patterning may be performed. The patterning is for efficiently diffusing the primary light emitted from the light guide plate so that the primary light easily comes into contact with the quantum dot dispersed in the polymer resin layer to facilitate the secondary light emission. The amount of quantum dots to be used can be remarkably reduced, and economical efficiency can be secured. When passing through this pattern, some of the light is recycled through reflection, thereby increasing the number and probability of meeting with the quantum dots, thereby reducing the amount of quantum dots and securing economical efficiency.

In one embodiment of the present invention, the polymeric resin layer may be a prism patterned. In the prism patterning, the prism pattern has a pitch of 20 to 70 mu m, a vertex angle of 95 to 120 DEG, and a cross-section of the pattern may be triangular. The quantum dot efficiency described above can be increased by forming the prism pattern below the polymer resin layer in which the quantum dots are dispersed.

Meanwhile, in another embodiment of the present invention, the polymer resin layer may be lens patterned. In the lens patterning, the pitch of the lens pattern is 20 to 70 mu m, the pitch to height ratio is 4: 1 to 10: 1, and the cross-section of the pattern may be semicircular. As described above, the quantum dot efficiency can be increased by forming the lens pattern below the polymer resin layer in which the quantum dots are dispersed.

The refractive index of the patterned polymer resin layer may be effective when the refractive index is in the range of 1.49 to 1.65. When the refractive index of the pattern layer is lower than 1.49, it is advantageous to diffuse the light in the primary light source, but the critical angle is reduced and the recycling of light due to the total reflection is significantly reduced. Conversely, when the refractive index is higher than 1.65, the total reflection light due to the increase in the critical angle increases and the recycling characteristics of the light remarkably improve. However, since the refractive index is too high,

Meanwhile, in another embodiment of the present invention, the polymer resin layer may be a prism pattern having a polygonal cross section or a lens pattern having an elliptical cross section. At this time, the dimension of the cross section may be the same as described above, and the refractive index may be the same.

Although the patterned polymer resin layer is slightly different depending on the pattern shape and the polymer resin layer thickness, the quantum dot usage can be reduced by 2 to 30%, and the brightness improved by about 10% or more compared to the optical sheet to which no pattern is applied .

Meanwhile, the polymer resin layer may include a first barrier film and a second barrier film on one surface and the other surface of the resin layer, respectively. It is to be understood that the first and second barrier films in the present invention are arbitrarily ordered in order to distinguish them from each other.

The barrier film serves to prevent the lifetime of the quantum dots in the polymer resin layer from being reduced due to penetration of moisture or oxygen. In one embodiment of the present invention, the barrier film includes a substrate, an organic A barrier layer and an inorganic barrier layer formed on the organic barrier layer.

The substrate may be a film of PET, COP, COC, PC, PMMA, TAC, polyimide, polyethylene naphthalene, etc. The substrate thickness is 25um, 38um, 50um, 75um, 100um, 125um, 188um, But is not limited thereto.

Meanwhile, in another embodiment of the present invention, the barrier film may include an organic barrier layer formed on a substrate and an inorganic barrier layer formed on the organic barrier layer.

In one embodiment of the present invention, the thickness of the organic barrier layer may be 300 to 1000 nm. The organic barrier layer can help to lower moisture and oxygen permeability by applying a material having a roughness and a barrier property to flatten the roughness of the substrate. If the thickness of the organic barrier layer is less than 300 nm, there is a problem in that the effect of flattening foreign matters, pinholes, and the like existing on the surface of the substrate is deteriorated, and if the organic barrier layer is more than 1000 nm, There may be a problem of degradation of water or oxygen permeation.

Meanwhile, in an embodiment of the present invention, the organic barrier layer may be formed of at least one selected from the group consisting of alkoxysilanes, polydimethylsiloxane, vinylmethoxysiloxane, polyphenylmethylsilsequinquinoxane, polyphenylalkylsiloxane, polydialkylsiloxane, silsesquioxane Fluorinated silicones, and hydride substituted silicon, or one or more materials selected from the group consisting of urethane acrylate, epoxy acrylate styrene, acrylate, norbornene, polyethylene and styrene-butyl -Styrene polymer, and a mixture of at least one substance selected from the group consisting of styrene-styrene polymers.

Meanwhile, in one embodiment of the present invention, the thickness of the inorganic barrier layer may be 20 to 200 nm. If the thickness of the inorganic barrier layer is less than 20 nm, oxygen and water shielding properties may be deteriorated. In addition, thickness uniformity may be deteriorated due to an ultra-thin film, , The price may increase. The quantum dot may have a typical size of 1 to 10 nm. When the quantum dot has a size of 4 to 5 nm, it may emit secondary light having a red color after absorbing the primary light from the light source. It is possible to emit secondary light having green after absorbing the primary light from the light source.

On the other hand, in one embodiment of the present invention, the inorganic barrier layer is a Si, Al, In, Sn, Zn, Zr, Ti, Cu, Ce, Yt, La, Ba, Mg, F _2, Sb, Sr, and Ta An oxide, a nitride, a carbide, an oxide nitride, an oxide carbide, a nitride carbide, or an oxynitride carbide containing at least one metal selected from the group consisting of oxides, nitrides,

Meanwhile, in an embodiment of the present invention, an overcoat layer may be formed on the inorganic barrier layer.

The overcoat layer is for enhancing the adhesion to the quantum dots and additionally serves to prevent defects present on the surface of the inorganic layer to prevent moisture and oxygen permeation. In one embodiment of the present invention, the thickness of the overcoat layer may be from 30 to 300 nm. If the thickness of the overcoat layer is less than 30 nm, the adhesion of the polymeric resin layer to the polymeric resin layer is reduced, which is unsuitable. If the overcoat layer has a thickness exceeding 300 nm, the product is defective due to adhesion at room temperature and reliability.

Meanwhile, in an embodiment of the present invention, the overcoat layer may be formed of a urethane acrylate, an epoxy acrylate, a urethane / epoxy acrylate, an ester acrylate, a silicon containing acrylate, a pentaerythritol triacrylate, a polyol modified urethane acrylate , Isocyanate silane modified acrylate, and hydroxyalkyl acrylate, or a mixture thereof.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope and content of the present invention can not be construed to be limited or limited by the following Examples. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. It is natural that it belongs to the claims.

Example

Example 1

A first barrier film and a barrier film having no pattern formation were placed between the laminator rolls and a second barrier film having a pitch of 20 탆 and a prismatic pattern having a triangular cross section and a vertex angle of 95 degrees and a refractive index of 1.49 was formed on one side of the barrier film , And the resin having the quantum dots dispersed between the first barrier film and the second barrier film is applied between the laminator rolls while adjusting the gap of the laminator roll so as to have a thickness of 60 탆. At this time, the speed was maintained at about 2.0 mpm. Thereafter, the polymer resin layer in which the quantum dots applied between the barrier films exiting the laminator roll was dispersed was UV-cured to complete the production of the optical sheet. At this time, the exposure amount is about 400 mJ / cm ² . The UV-cured UV-Ramp type was Fusion's non-electrode type D-bulb. The barrier film was 125 μm thick and WVTR = 10 ^-2 g / m ² / day.

Example 2

And the vertex angle was 110 degrees.

Example 3

The same procedure as in Example 1 was carried out and the vertex angle was 120 degrees.

Example 4

The same procedure as in Example 1 was carried out and the pitch was applied at a 50-degree angle of 95 degrees.

Example 5

And the angle was set at 110 degrees.

Example 6

And the angle was 120 degrees.

Example 7

The same procedure as in Example 1 was carried out and the pitch was applied at a 70-degree angle of 95 degrees.

Example 8

And the angle was changed to 110 degrees.

Example 9

And the angle was 120 degrees.

Example 10

A first barrier film not patterned and a second barrier film having a lens pattern formed with a pitch of 20 um, a height of 5 um, and a refractive index of 1.49 on one side of the barrier film were placed between the laminator rolls, The resin having the quantum dots dispersed between the second barrier films is applied between the laminator rolls while adjusting the gap of the laminator roll so that the thickness is 60 탆. At this time, the speed is kept at about 2.0mpm. Thereafter, the polymer resin layer in which the quantum dots applied between the barrier films exiting the laminator roll was dispersed was UV-cured to complete the production of the optical sheet. At this time, the exposure amount is about 400 mJ / cm ² . The UV-cured UV-Ramp type was Fusion's non-electrode type D-bulb. The barrier film was 125 μm thick and WVTR = 10 ^-2 g / m ² / day.

Example 11

Was prepared in the same manner as in Example 10 and applied at a height of 4 탆.

Example 12

Was prepared in the same manner as in Example 10 and applied at a height of 2 mu m.

Example 13

A pitch of 50 μm and a height of 12.5 μm were applied in the same manner as in Example 10.

Example 14

Was prepared in the same manner as in Example 13, and a height of 10 탆 was applied.

Example 15

Was prepared in the same manner as in Example 13 and applied at a height of 5 mu m.

Example 16

A pitch of 70 μm and a height of 17.5 μm were applied in the same manner as in Example 10.

Example 17

Was prepared in the same manner as in Example 16, and a height of 14 mu m was applied.

Example 18

The structure was fabricated in the same manner as in Example 16, and the height was adjusted to 17 mu m.

Example 19

A second barrier film having a 50 μm pitch, a triangular cross section, a vertex angle of 95 ° and a refractive index of 1.49 and a prism pattern formed on one side of the first barrier film and the barrier film not patterned was placed between the laminator rolls , And the resin having the quantum dots dispersed between the first barrier film and the second barrier film is applied between the laminator rolls while adjusting the gap of the laminator roll so as to have a thickness of 60 탆. At this time, the speed was maintained at about 2.0 mpm. Thereafter, the polymer resin layer in which the quantum dots applied between the barrier films exiting the laminator roll was dispersed was UV-cured to complete the production of the optical sheet. At this time, the exposure amount is about 400 mJ / cm ² . The UV lamp used for UV curing was a Fusion D-bulb, and the barrier film was 125 μm thick and WVTR = 10 ^-2 g / m ² / day.

Example 20

And the refractive index of the pattern layer was 1.53.

Example 21

And the refractive index of the pattern layer was 1.57.

Example 22

And the refractive index of the pattern layer was 1.62.

Comparative Example 1

While the first barrier film and the second barrier film were placed between the laminator rolls and the gap of the laminator roll was adjusted so that the resin having the quantum dots dispersed between the first barrier film and the second barrier film had a thickness of 60 um, . At this time, the speed is kept at about 2.0mpm. Thereafter, the polymer resin layer in which the quantum dots applied between the barrier films exiting the laminator roll was dispersed was UV-cured to complete the production of the optical sheet. At this time, the exposure amount is about 400 mJ / cm ² . The UV-cured UV-Ramp type was Fusion's non-electrode type D-bulb. The barrier film was 125 μm thick and WVTR = 10 ^-2 g / m ² / day.

Comparative Example 2

And the resin layer thickness was made to be 25 탆.

Comparative Example 3

And the resin layer thickness was made to be 50 탆.

Comparative Example 4

And the resin layer thickness was made to be 72 mu m.

Comparative Example 5

And the resin layer thickness was made 100 μm.

[Method for Measuring Luminance]

- Measuring equipment: Topcon SR-3AR equipment

- BLU: edge type (1H) emitting blue light of 446 nm;

- Sheet structure: Optical sheet Single item Located on top of LGP

- Sheet size: 15cm × 15cm

Experimental Example 1

Comparison of luminance property according to pattern shape Pattern shape Pitch (um) Angle (°) or height (um) Resin Layer Thickness (um) Brightness (%) Comparative Example 1 - - - 60 100 Example 1 prism 20 95 60 109.5 Example 2 110 60 112 Example 3 120 60 115 Example 4 50 95 60 112 Example 5 110 60 116 Example 6 120 60 117 Example 7 70 95 60 115 Example 8 110 60 117.5 Example 9 120 60 118 Example 10 lens 20 5 60 115 Example 11 4 60 112 Example 12 2 60 110 Example 13 50 12.5 60 117.5 Example 14 10 60 115 Example 15 5 60 111.5 Example 16 70 17.5 60 117 Example 17 14 60 114 Example 18 7 60 112

Comparison of luminance properties according to thickness of polymer resin layer dispersed with quantum dots Resin Layer Thickness (um) Brightness (%) Comparative Example 1 60 100 Comparative Example 2 25 66 Comparative Example 3 50 86 Comparative Example 4 72 116 Comparative Example 5 100 135

Referring to Tables 1 and 2, although the optical sheets of Examples 1 to 18 pattern-formed on one side of the polymer resin layer as in the present invention, in comparison with the optical sheets having the same resin layer thickness, It can be confirmed that it has remarkably improved luminance physical properties.

Comparison of luminance properties according to refractive index of polymer resin layer dispersed with quantum dots Resin Layer Thickness (um) The refractive index of the patterned polymeric resin layer Pitch (um) Angle (°) Brightness (%) Comparative Example 1 60 - - - 100 Example 19 60 1.49 50 95 112 Example 20 60 1.53 115 Example 21 60 1.57 118 Example 22 60 1.62 121

On the other hand, referring to Table 3, optical sheets (Examples 19 to 22) including a patterned polymer resin layer having a refractive index in the range disclosed in the present invention have improved brightness characteristics I could confirm.

Claims (19)

A polymer resin layer in which a plurality of non-cadmium-based quantum dots are dispersed in a polymer resin and patterned on one side or both sides;
A first barrier film formed on one side of the polymer resin layer; And
And a second barrier film formed on another side of the polymeric resin layer. The method according to claim 1,
The polymer resin may be at least one selected from the group consisting of epoxy, epoxy acrylate, lauryl acrylate, norbornene, polyethylene, polystyrene, ethylene-styrene copolymers, acrylates containing bisphenol A and bisphenol A derivatives, acrylates containing fluorene derivatives, Wherein the at least one polymer resin is at least one polymer resin selected from the group consisting of isobornyl acrylate, polyphenylalkylsiloxane, polydiphenylsiloxane, polydialkylsiloxane, silsesquioxane, silicone fluoride, vinyl and hydride substituted silicone. The method according to claim 1,
The polymer resin has moisture permeability of ^{WVTR = 10 -2 g / m 2} / day or less, and
An optical sheet having an oxygen permeability of OTR = 10 ^-2 cc / m ² / day or less. The method according to claim 1,
Wherein the non-cadmium-based quantum dots are at least one inorganic material selected from the group consisting of Group II-VI, Group III-V, Group IV-VI, and Group IV semiconductors. The method according to claim 1,
The non-cadmium-based quantum dots include Si, Ge, Sn, Se, Te, B, C, P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, ZnSe, ZnTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si 3 N 4, Ge 3 N 4 , and the optical sheet of inorganic material at least one selected from the group consisting of a combination thereof. The method according to claim 1,
Wherein the polymeric resin layer has a thickness of 10 to 100 m. The method according to claim 1,
Wherein the lower surface of the polymer resin layer is prismatic. 8. The method of claim 7,
Wherein the pitch of the prism pattern is 20 to 70 占 퐉, the apex angle is 95 to 120 占 and the cross-section of the pattern is triangular. The method according to claim 1,
And the lower surface of the polymer resin layer is lens-patterned. 10. The method of claim 9,
Wherein the pitch of the lens pattern is 20 to 70 mu m, the pitch to height ratio is 4: 1 to 10: 1, and the cross section of the pattern is a semicircular shape. The method according to claim 1,
And the refractive index of the patterned polymeric resin layer is 1.49 to 1.65. The method according to claim 1,
Wherein the barrier film comprises a substrate, an organic barrier layer formed on the substrate, an inorganic barrier layer formed on the organic barrier layer, and an overcoat layer formed on the inorganic barrier layer. 13. The method of claim 12,
Wherein the substrate is PET, COP, COC, PC, PMMA, TAC, polyimide or polyethylene naphthalene film. 13. The method of claim 12,
Wherein the organic barrier layer has a thickness of 300 to 1000 nm. 13. The method of claim 12,
Wherein the organic barrier layer is selected from the group consisting of alkoxysilanes, polydimethylsiloxane, vinylmethoxysiloxane, polyphenylmethylsilsequinquinoxane, polyphenylalkylsiloxane, polydialkylsiloxane, silsesquioxanes, fluorinated silicones, and hydride substitution Silicon, or one or more materials selected from the group consisting of silicon,
The optical sheet according to any one of claims 1 to 3, wherein the material to be selected is a mixture of a mixture of urethane acrylate, epoxy acrylate styrene, acrylate, norbornene, polyethylene and styrene- . 13. The method of claim 12,
Wherein the inorganic barrier layer has a thickness of 20 to 200 nm. 13. The method of claim 12,
The inorganic barrier layer is at least one metal selected from the group consisting of Si, Al, In, Sn, Zn, Zr, Ti, Cu, Ce, Yt, La, Ba, Mg, F 2, Sb, Sr , and Ta Wherein the optical sheet contains an oxide, a nitride, a carbide, an oxynitride, an oxide carbide, a nitride carbide, or a oxynitride carbide. 13. The method of claim 12,
Wherein the thickness of the overcoat layer is 30 to 300 nm. 13. The method of claim 12,
Wherein the overcoat layer is selected from the group consisting of urethane acrylate, epoxy acrylate, urethane / epoxy acrylate, ester acrylate, silicon containing acrylate, pentaerythritol triacrylate, polyol modified urethane acrylate, isocyanate silane modified acrylate and hydroxyalkyl Acrylate, or a mixture thereof.

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