KR20190055878A - Bright enhancing film and preparing method of the same - Google Patents

Abstract

The present invention relates to a brightness improving film and a manufacturing method thereof. The brightness improving film includes: a base film; an YAG-based fluorescent layer coating the upper part of the base film; and a low-refraction layer coating the lower part of the base film or the upper part of the YAG-based fluorescent layer. The manufacturing method thereof includes: a step of making an YAG-based fluorescent coating solution by evenly spreading fluorescent substances over a polymer matrix, and forming the YAG-based fluorescent layer by coating the upper part of the base film with the YAG-based fluorescent coating solution, and then, hardening the layer with ultraviolet rays; and a step of forming the low-refraction layer by coating the upper part of the YAG-based fluorescent layer or the lower part of the base film with a low-refraction coating solution containing a urethane acrylate oligomer and hollow nano-silica, and then, hardening the layer with ultraviolet rays. Therefore, the brightness improving film is provided with improved brightness, color reproductivity, and physical properties.

Description

Brightening Enhancing Film and Preparation Method Thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brightness enhancement film and a method of manufacturing the brightness enhancement film, and more particularly, to a brightness enhancement film and a method of manufacturing the same that can improve brightness, color reproducibility and physical properties.

Recently, the display market is evolving from a large-size and high-resolution competition to a color competition, and attention is focused on manufacturing a display capable of realizing excellent color.

OLED (Organic Light-Emitting Diode), which is widely regarded as the next generation display, can achieve the color recall rate up to 100% of NTSC. However, currently used LCD shows 70% color reproduction rate It is a situation.

Accordingly, although a method using a quantum dot is applied to improve the color gamut of an LCD, there is a problem that a sealing process through a barrier film must be accompanied by inherent characteristics of quantum dots susceptible to moisture and oxygen.

On the other hand, in the LCD, a luminance enhancement film is applied in order to increase the contrast. The brightness enhancement film can be attached to a back light unit (BLU) using a light shielding tape. The reflection type polarizing film is a film in which a high refractive index layer and a low refractive index layer are alternately repeatedly laminated, and commercially available is a dual brightness enhancement film (DBEF) ) Are used.

However, since royalty is required to use DBEF, Korean affiliates are concentrating their research and development on localization of luminance enhancement film that can replace DBEF.

Therefore, if a film that can improve the luminance of LCD without using DBEF is developed, it is expected to contribute to the activation of the domestic display market.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a brightness enhancement film and a manufacturing method thereof that can improve brightness, color reproduction rate, and physical characteristics to replace DBEF.

As means for solving the above-mentioned technical problem,

The present invention relates to a film comprising: a base film; A YAG-base phosphor layer coated on the base film; And a low refraction layer coated on the upper side of the YAG-base phosphor layer or the lower side of the base film.

In this case, the low refraction layer includes a urethane acrylate oligomer, and the urethane acrylate oligomer may have a fluorinated polyol as a main chain.

In this case, the urethane acrylate oligomer may be contained in an amount of 10 to 20 wt% with respect to the low refractive layer.

In this case, the low refraction layer may include hollow nanosilica.

In this case, the hollow nanosilica may be contained in an amount of 30 to 70 wt% with respect to the low refractive index layer.

In this case, the coating thickness of the low refraction layer may be 70 to 120 nm.

In this case, the refractive index of the low refractive index layer may be 1.32 to 1.42.

The present invention also provides a method for producing a YAG-based phosphor, comprising the steps of: (a) preparing a YAG-based phosphor coating solution by uniformly dispersing a YAG-based phosphor in a polymer matrix, coating the YAG- Irradiation and curing; And (b) coating a low refraction coating liquid containing a urethane acrylate oligomer and hollow nanosilica on the upper side of the YAG-base phosphor layer or the lower side of the base film to form a low refraction layer, and then curing the ultraviolet ray; The present invention also provides a method for producing a brightness enhancement film.

According to the present invention, when the YAG-base phosphor is coated on the upper surface of the base film, it is possible to improve the brightness when applied to an LCD, thereby realizing excellent brightness.

Further, the brightness can be further improved by further coating a lower refraction layer on the upper portion of the YAG-base phosphor layer, the lower portion of the base film, the upper portion of the YAG-base phosphor layer and the lower portion of the base film.

In addition, physical properties such as pencil hardness, adhesive force, curl, flex resistance and the like can be secured by dispersing the YAG-base phosphor in a polymer matrix and coating the base film.

In addition, it exhibits excellent durability as compared with the quantum dot film, and it is possible to manufacture a film having a relatively thin thickness because a barrier film is not required.

1 is a laminated structure of a brightness enhancement film according to the present invention,
FIGS. 2 and 3 are laminated structure views showing a modified example of the brightness enhancement film shown in FIG. 1. FIG.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

FIG. 1 is a laminated structure of a brightness enhancement film according to the present invention, and FIGS. 2 and 3 are laminated structure views showing a modified example of the brightness enhancement film shown in FIG.

1 to 3, the brightness enhancement film 100 according to the present invention includes a base film 110, a YAG (yttrium aluminum garnet) phosphor layer 120, and a low refractive index layer 130.

The base film 110 may be a film of a material such as PET, TAC, PC, Polyimide, Acryl, and the like, and is not particularly limited.

The YAG-base phosphor layer 120 is formed on one surface of the base film 110, here the top surface, for the purpose of improving brightness. In this case, the YAG-base phosphor 122 constituting the YAG-base phosphor layer 120 is made of Y ₃ Al ₅ 0 ₁₂ : Ce ³⁺ (YAG: Ce), Tb ₃ Al ₅ 0 ₁₂ : Ce ³⁺ (TAG: Ce) , Ca ₃ (Sc, Mg) ₂ Si ₃ O ₁₂ : Ce ³⁺ , and Y ₃ Mg ₂ AlSi ₂ O ₁₂ : Ce ³⁺ .

The YAG-base phosphor layer 120 is formed by dispersing a YAG-base phosphor 122 in a polymer matrix 121 so as to secure physical properties such as pencil hardness, adhesion, Curl, And the like.

In this case, the polymer matrix 121 may be selected from monofunctional urethane acrylate oligomers, monofunctional monomers, photoinitiators, leveling agents, antifoaming agents and initiators.

The YAG-base phosphor 122 is added in a proportion of 10 to 40 wt% with respect to 100 wt% of the coating solution comprising the YAG-base phosphor 122 and the polymer matrix 121. If the content of the YAG-base phosphor 122 is less than 10 wt%, the desired brightness enhancement effect can not be exhibited. If the content is more than 40 wt%, the coating is difficult and the color reproduction rate is lowered.

The thickness of the YAG-base phosphor layer 120 is preferably 10 to 100 占 퐉. If the coating thickness is less than 10 μm, the YAG-base phosphor 122 may protrude to cause defects in appearance. If the thickness exceeds 100 μm, curl characteristics may deteriorate during coating, and the resin applicable to the polymer matrix 121 may be limited .

1) of the YAG-base phosphor layer 120, a lower portion (see FIG. 2) of the base film 110 (see FIG. 2), or a YAG-based phosphor layer (See FIG. 3) of the base film 110 and the upper portion of the phosphor layer 120, respectively.

The coating solution for forming the low refraction layer 130 may include a urethane acrylate oligomer, a polyfunctional monomer, a monofunctional monomer, a photoinitiator, a leveling agent, a dispersant, and hollow nanosilica.

In this case, the urethane acrylate oligomer has the following structure.

In this case, x, y, z, and n in R " are integers between 0 and 50.

That is, the urethane acrylate oligomer has a fluorinated polyol as a main chain and is contained in an amount of 10 to 20% with respect to the low refractive layer 130. When the content of the fluorinated polyol is less than 10 wt%, the refractive index of the low refractive layer 130 is increased to cause optical loss. When the content of the fluorinated polyol is more than 20 wt%, the monomer content is decreased to decrease the crosslink density, it's difficult. Also, the polyfunctional monomer and the monofunctional monomer may be composed of PETA (pentaerythritol triacrylate) and ACMO (acryloyl morpholine), and they are contained in a proportion of 20 to 30 wt%. The photoinitiator, leveling agent and dispersant may be contained in an amount of 1 to 5 wt%.

On the other hand, hollow nanosilica can be hollow nanosilica manufactured by Nippon Shokubai Co., Ltd., and it is preferable that 30 to 70 wt% of the hollow nanosilica is included in the low refractive index layer 130. If the content of the hollow nanosilica is less than 30 wt%, the reflectance increases by 2.5% or more to cause transmission light loss. If the content of the hollow nanosilica is more than 70%, the dispersion of the hollow nanosilica particles occurs and the appearance becomes uneven.

The low refraction layer 130 may be coated by bar coating, slot-die coating, micro gravure coating, or the like.

The thickness of the low refractive layer 130 is preferably 70 to 120 nm. When the thickness of the low refraction layer 130 is less than 70 nm or exceeds 120 nm, the reflectance increases and a phenomenon of brightness decrease due to transmission light loss may occur.

The refractive index of the low refractive index layer 130 is preferably 1.32 to 1.42, and more preferably 1.34 to 1.38 in terms of luminance improvement.

Meanwhile, the brightness enhancement film 100 may further include a back coating layer (not shown). The back coating layer is formed by the particles included in the back coating layer to provide irregularities on the back surface of the brightness enhancement film 100 to prevent blocking with other optical sheets to improve workability and to prevent static electricity Function.

In the present invention, the back coating may be a bar coating method or a slot-die coating method. The coating solution used for the back coating layer may include a urethane acrylate oligomer, a monofunctional monomer, a photoinitiator, a leveling agent, .

In this case, the PMMA particles are preferably contained in an amount of 0.1 to 5 wt% with respect to the entire back coating layer. When the content of PMMA particles is less than 0.1 wt%, sufficient irregularities can not be formed on the back surface of the brightness enhancement film. If the content of PMMA particles is more than 5 wt%, transmitted light loss due to high haze occurs. Therefore, the haze of the back coating layer is adjusted to 1 To 20%.

An antistatic agent may be added to the back coat layer as an additive if necessary. The surface resistance can be controlled by adding an antistatic agent, and the antistatic agent is preferably contained in an amount of 0.01 to 3 wt% with respect to the whole of the back coat layer. When the content of the antistatic agent is less than 0.01wt%, and a lack of surface resistance for antistatic, 3wt% excess if it results in the addition of excess amount more than necessary to the antistatic agent 0.01 ~ 3wt% surface resistance of 10 ¹⁰ to 10 by the addition ¹² Ohm / < / RTI >< / RTI > This is because, when the surface resistance is 10 ¹⁰ to 10 ¹² Ohm / square, it is possible to prevent the film from being damaged in the dynamic state, and there is an effect that the charging phenomenon immediately after charging immediately attenuates.

The thickness of the back coating layer is preferably 1 to 10 mu m. If the thickness of the back coating layer is less than 1 mu m, sufficient irregularities are not formed on the back surface of the brightness enhancement film 100 to prevent blocking, and if it is more than 10 mu m, there is a problem of transmission light loss due to high haze.

The brightness enhancement film according to the present invention has been described above. Hereinafter, a method for manufacturing a brightness enhancement film according to the present invention will be described.

First, a YAG fluorescent material 122 is uniformly dispersed in a polymer matrix 121 selected from a monofunctional urethane acrylate oligomer, a monofunctional monomer, a photoinitiator, a leveling agent, a defoaming agent, and an initiator at a concentration of 10 to 40 wt% The coating solution thus prepared is coated on the base film 110 to a thickness of 10 to 100 μm, and then irradiated with ultraviolet rays to cure the YAG-based phosphor layer 120.

Thereafter, a coating solution containing a urethane acrylate oligomer, a polyfunctional monomer, a monofunctional monomer, a photoinitiator, a leveling agent, a dispersant, and hollow nanosilica is coated on the upper surface of the YAG-base phosphor layer 120, The brightness enhancement film 100 is completed by coating the upper portion of the YAG-base phosphor layer 120 and the lower portion of the base film 110 and forming the low refractive layer 130 by irradiating ultraviolet rays to cure.

In this case, as a coating method of the YAG-base phosphor layer 120 and the low refractive index layer 130, a bar coating, a spin coating and a slot-die coating may be used, but it is preferable to coat the YAG-base phosphor layer 120 and the low refractive layer 130 by a slot-die coating method. In addition, a metal halide lamp, a mercury high-pressure lamp, and a non-electrode lamp can be used for ultraviolet ray irradiation after coating, but it is preferable to irradiate with a non-electrode lamp in a nitrogen atmosphere. The curing time is preferably 1 to 10 seconds.

The method for manufacturing the brightness enhancement film according to the present invention has been described above. Hereinafter, embodiments of the present invention will be described. The present invention can be understood more clearly by the following examples, which are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

Example 1

400 g (40 wt%) of urethane (meth) acrylate (Ebecryl 1290, Korea) was added to a reactor equipped with a stirrer, and 400 g (40 wt%) of isobonyl acrylate as a reactive monomer diluent and 2-hydroxyethyl acrylate 10 g (1 wt%) of BYK307, a leveling agent, 10 g (1 wt%) of BYK307, 10 g (1 wt%) of FA-4420, a fluorescent dispersant BASF, and 10 g 20 g (2 wt%) of Irgacure 184, a photoinitiator manufactured by BASF, was added, 100 g (10 wt%) of YAG phosphor was added and stirred at 400 rpm for 30 minutes at room temperature to obtain a transparent liquid composition having a viscosity of 1,000 cps. Thereafter, the prepared coating solution was coated on one side of the PET film with a Bar Coater to a thickness of 50 μm, and irradiated with ultraviolet rays for about 5 seconds using a non-electrode lamp. In this case, the amount of irradiated ultraviolet light was set to 1000 mj or less. Lastly, on the top of the prepared phosphor-coated PET film, a 100 nm thick single-sided and double-sided coating was performed using a Slot Die Coater of JSR Corporation, a low refraction coating liquid TU2359, and then irradiated with ultraviolet rays for about 5 seconds using a non- Respectively. In this case, the amount of irradiated ultraviolet light was set to 1000 mJ or less.

Example 2

400 g (40 wt%) of urethane (meth) acrylate (Ebecryl 1290, Korea) was added to a reactor equipped with a stirrer, and 400 g (40 wt%) of isobonyl acrylate as a reactive monomer diluent and 2-hydroxyethyl acrylate 10 g (1 wt%) of BYK307, a leveling agent, 10 g (1 wt%) of BYK307, 10 g (1 wt%) of FA-4420 of a fluorescent dispersant BASF, and 10 g 20 g (2 wt%) of Irgacure 184, a photoinitiator manufactured by BASF, was added, 200 g (20 wt%) of YAG fluorescent material was added and stirred at 400 rpm for 30 minutes at room temperature to obtain a transparent liquid composition having a viscosity of 1,000 cps. Thereafter, the prepared coating solution was coated on one side of the PET film with a Bar Coater to a thickness of 50 μm, and irradiated with ultraviolet rays for about 5 seconds using a non-electrode lamp. In this case, the amount of irradiated ultraviolet light was set to 1000 mj or less. Lastly, on the top of the prepared phosphor-coated PET film, a 100 nm thick single-sided and double-sided coating was performed using a Slot Die Coater of JSR Corporation, a low refraction coating liquid TU2359, and then irradiated with ultraviolet rays for about 5 seconds using a non- Respectively. In this case, the amount of irradiated ultraviolet light was set to 1000 mJ or less.

Example 3

400 g (40 wt%) of urethane (meth) acrylate (Ebecryl 1290, Korea) was added to a reactor equipped with a stirrer, and 400 g (40 wt%) of isobonyl acrylate as a reactive monomer diluent and 2-hydroxyethyl acrylate 10 g (1 wt%) of BYK307, a leveling agent, 10 g (1 wt%) of BYK307, 10 g (1 wt%) of FA-4420, a fluorescent dispersant BASF, and 10 g 20 g (2 wt%) of Irgacure 184, a photoinitiator manufactured by BASF, was added, 300 g (30 wt%) of YAG phosphor was added and stirred at 400 rpm for 30 minutes at room temperature to obtain a transparent liquid composition having a viscosity of 1,000 cps. Thereafter, the prepared coating solution was coated on one side of the PET film with a Bar Coater to a thickness of 50 μm, and irradiated with ultraviolet rays for about 5 seconds using a non-electrode lamp. In this case, the amount of irradiated ultraviolet light was set to 1000 mj or less. Lastly, on the top of the prepared phosphor-coated PET film, a 100 nm thick single-sided and double-sided coating was performed using a Slot Die Coater of JSR Corporation, a low refraction coating liquid TU2359, and then irradiated with ultraviolet rays for about 5 seconds using a non- Respectively. In this case, the amount of irradiated ultraviolet light was set to 1000 mJ or less.

Comparative Example 1

A brightness enhancement film was prepared in the same manner as in Example 1, except that the low refractive layer was not coated.

Comparative Example 2

A brightness enhancement film was produced in the same manner as in Example 3, except that the low refractive layer was not coated.

Experimental Example

The brightness enhancement film prepared according to Examples and Comparative Examples was cut into A4 size to produce an LCD. The front brightness and color reproduction rate of the brightness enhancement film were measured through a luminance measuring apparatus (Topcon BM-7 FAST color difference luminance meter, Japan) And the results are shown in Table 1 below. In this case, the LCD is constituted by sequentially arranging a reflective plate, a light source (Blue LED), a brightness enhancement film, a prism, and a liquid crystal display panel. For reference, the experimental data in the case where the low refractive index layer is not formed on the brightness enhancement film in the present invention is specifically disclosed in Patent Application No. 10-2017-0150062 filed by the present applicant.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Low refraction layer coating section both sides section both sides section both sides - - Color recall (%) 81.3 81.3 82.6 82.6 82.2 82.2 81.3 82.6 Brightness (nit) 441 452 492 504 523 536 430 480

100: brightness enhancement film 110: substrate film
120: YAG-base phosphor layer 121: polymer matrix
122: YAG-base phosphor 130: low refractive layer

Claims (8)

A base film;
A YAG-base phosphor layer coated on the base film; And
A low refraction layer coated on an upper portion of the YAG-base phosphor layer or a lower portion of the base film;
. The method according to claim 1,
Wherein the low refraction layer comprises a urethane acrylate oligomer, and the urethane acrylate oligomer has a fluorinated polyol as a main chain. 3. The method of claim 2,
Wherein the urethane acrylate oligomer is contained in an amount of 10 to 20 wt% with respect to the low refraction layer. The method according to claim 1,
Wherein the low refraction layer comprises hollow nanosilica. 5. The method of claim 4,
Wherein the hollow nanosilica is contained in an amount of 30 to 70 wt% with respect to the low refractive index layer. 6. The method according to any one of claims 1 to 5,
Wherein the low refraction layer has a coating thickness of 70 to 120 nm. 6. The method according to any one of claims 1 to 5,
Wherein the low refraction layer has a refractive index of 1.32 to 1.42. (a) preparing a YAG-based phosphor coating liquid by uniformly dispersing a YAG-base phosphor in a polymer matrix, coating the YAG-based phosphor coating liquid on a base film to form a YAG-based phosphor layer, ; And
(b) coating a low refraction coating liquid containing urethane acrylate oligomer and hollow nanosilica on the upper side of the YAG-base phosphor layer or the lower side of the base film to form a low refraction layer and curing the ultraviolet ray;
Wherein the brightness enhancement film is formed by a method comprising the steps of:

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