KR101686210B1 - Diffusion sheet comprising yellow phosphor - Google Patents

Abstract

The diffusion sheet according to the present invention is characterized in that in the diffusion sheet comprising a base layer and a diffusion layer, the diffusion layer comprises 0.5 to 2.5 parts by weight of an amorphous (yellow) inorganic phosphor per 100 parts by weight of the plastic resin. The diffusion sheet of the present invention can be usefully used as a diffusion sheet for a high color reproducible LCD TV since the diffusion sheet of the present invention can absorb light of a blue wavelength and emit light having a longer wavelength to enhance yellow intensity .

Description

DIFFUSION SHEET COMPRISING YELLOW PHOSPHOR < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffusion sheet including a yellow phosphor, and more particularly, to a diffusion sheet comprising a backlight unit of a liquid crystal display (LCD) TV of a high color reproduction type back light unit (BLU).

In general, a flat display is classified into a light emitting type and a light receiving type. As an example of the light receiving type flat panel display, a liquid crystal display device can be used. Such a liquid crystal display device itself can not emit light to form a liquid crystal image, and light must be incident from the outside to form a liquid crystal image.

Accordingly, the liquid crystal display device which can not emit light itself can illuminate the backlight unit evenly so that the display image can be seen from the back side of the liquid crystal display device (LCD). The backlight unit includes a light emitting diode (LED) as a light source, and a light guide plate for uniformly dispersing light emitted from the light source over the entire area of the liquid crystal screen. The diffusion sheet includes a diffusing sheet for uniformly refracting, diffusing, and diffusing the light of the backlight light source passed through the light guide plate in various directions. The diffusion sheet improves the light guide plate pattern lightness, The role of

In recent years, curved LCD TVs similar in design to organic light emitting diodes (OLEDs) have emerged, followed by LCD TVs that have improved color reproducibility following pixels and designs. However, despite the fact that the LCD is approaching the OLED while realizing the curved surface, the color reproducibility still does not reach the OLED. Therefore, it is necessary to improve the color reproducibility and compensate for the disadvantages of the LCD display. Recently, interest in image quality has increased due to the rapid growth of ultra-high quality (UHD) market. According to the industry, major display panel makers are currently developing panels that increase LCD color reproducibility to OLED levels. In order to overcome these limitations, major panel makers are pushing up color reproduction with material innovation. A typical example is Quantum Dot (QD) film. When using such a QD film, it is the most important advantage that the color reproducibility can be improved only by the film without changing the structure. However, since the cost of the film is more than 100 dollars per film, a diffusion sheet, which is an optical sheet having improved color reproducibility as a QD film substitute, is required.

Accordingly, an object of the present invention is to provide a diffusion sheet capable of absorbing light having a blue wavelength and enhancing strength of yellow by emitting light having a longer wavelength.

Another object of the present invention is to provide a backlight unit including the diffusion sheet and an LCD TV having high color reproducibility including the backlight unit.

In order to achieve the above object, the present invention provides a light emitting device comprising a base layer and a diffusion layer, wherein the diffusion layer is formed of a plastic resin and a diffusion sheet containing 0.5 to 2.5 parts by weight of an amorphous (yellow) inorganic phosphor per 100 parts by weight of the plastic resin. Lt; / RTI >

According to another aspect of the present invention, there is provided an LCD TV including the backlight unit including the diffusion sheet and the backlight unit.

The diffusion sheet of the present invention including the yellow inorganic phosphor can enhance the yellow intensity by absorbing light of a blue wavelength and emit light having a longer wavelength and can be usefully used as a diffusion sheet for a high color reproducible LCD TV have.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram schematically showing a cross section of constituent articles constituting a typical backlight unit. Fig.
2 is a cross-sectional view of a diffusion sheet according to an example of the present invention.

Hereinafter, the present invention will be described in more detail.

The present invention provides a diffusion sheet comprising a base layer and a diffusion layer, wherein the diffusion layer comprises a plastic resin and 0.5 to 2.5 parts by weight of an amorphous (yellow) inorganic phosphor per 100 parts by weight of the plastic resin.

The diffusion sheet of the present invention is used as a component of a backlight unit for an LCD TV and diffuses and scatters light incident through the light guide plate to uniformize the brightness of the entire screen. The diffusion sheet may have a thickness of 25 to 320 탆, but is not limited thereto.

Hereinafter, the base layer and the diffusion layer constituting the diffusion sheet of the present invention will be described.

(1)

The base layer used in the present invention is not particularly limited as long as it is a material that transmits active energy such as ultraviolet rays, visible rays, and electron beams. Specific examples thereof include flexible polyester resins, acrylic resins, polycarbonate resins, (Meth) acrylamide-based resins. Particularly preferred are poly (meth) acrylate having a refractive index lower than that of the pattern portion and having a low surface reflectance, a mixture of polymethyl acrylate and polyfluorovinylidene resin, a polyester such as polycarbonate resin and polyethylene terephthalate Based resin is preferably used. More preferably, a PET film can be used. Such a substrate layer may be 20 to 300 [mu] m thick.

(2)

The diffusion layer of the present invention includes a plastic resin and an amorphous (yellow) inorganic phosphor.

The diffusion layer of the present invention can be produced by a conventional method for producing a sheet or film such as injection, extrusion, wet coating, casting or the like, and can also be produced to form a coating layer in the form of a sheet by coating on the upper surface of the base layer. Preferably, the diffusion layer of the present invention can be formed on the base layer by a wet coating method.

The diffusion layer of the present invention may have a thickness of 5 to 20 mu m, preferably 5 to 15 mu m, more preferably 10 to 15 mu m.

 (2-1) Plastic resin

The plastic resin may be a thermosetting resin, a UV-curable resin, a moisture-curable resin, or a mixture thereof. The thermosetting resin, UV-curable resin or moisture-curable resin may be epoxy resin, phenol resin, urethane resin, (Meth) acrylate resin, an unsaturated polyester resin, a polyester resin, a polyester resin, a polyester resin, a polyester resin, a polyester resin, a polyester resin, (Meth) acrylate resin, a phenol resin, an epoxy resin, a urea formaldehyde resin, a melamine formaldehyde resin, and a (meth) acrylate resin. And mixtures thereof. Preferably a thermosetting resin excellent in heat resistance, moisture resistance and UV resistance, which is a resin used for a general light-shielding diffusion sheet, can be used.

(2-2) Irregular yellow inorganic phosphor

The amorphous yellow inorganic phosphor is contained in a diffusion layer constituting a diffusion sheet to absorb a part of light emitted from a light source (LED) having a blue wavelength, emit light of a wavelength different from the wavelength of the emitted light, Permeability, thereby enhancing the strength of yellow color. Preferably, the amorphous yellow inorganic phosphor may emit light having a longer wavelength after absorbing light having a blue wavelength. Examples of the amorphous yellow inorganic phosphor include a La ₃ Si ₆ N ₁₁ : Ce phosphor, a (La, Y) ₃ Si ₆ N ₁₁ : Ce phosphor, a YAG: Ce (Y _{3 Al 5} O ₁₂ : Ce ³⁺ ) include those selected from the group consisting ^{_{of: (Ce 3+ Ca 2 BO 3}} Cl) phosphor sialon (siAlON) phosphor, (Ca ₂ BO ₃ Cl _{2 +} Eu) phosphor and.

The amorphous yellow inorganic phosphor may have a particle size of 0.01 to 20 탆, preferably 0.1 to 10 탆, more preferably 1 to 5 탆. When the particles of the amorphous yellow inorganic phosphor are 0.01 μm or more, the blue light is absorbed to emit light having a longer wavelength. When the size of the amorphous yellow inorganic phosphor is 20 μm or less, uniform dispersion can be maintained. In general, a phosphor having a micrometer-sized size uses crystal powders of 0.01 to 20 μm depending on applications. The luminous efficiency of the phosphor increases as the particle size increases, and is optimized in the vicinity of 2 to 15 μm.

The amorphous yellow inorganic phosphor is an amorphous type in which the overall shape does not have a specific shape. In general, inorganic phosphors are prepared by mixing, drying, calcining and pulverizing metal oxides using a solid-state-reaction method. In this case, the solid phase reaction between the particles causes uneven composition and particle size, The purity is lowered and the fluorescence property is lowered due to long-time pulverization and contamination. Accordingly, the inorganic phosphor is heat-treated at a high temperature so as to exhibit excellent fluorescence characteristics by increasing the crystallinity and purity of the inorganic phosphor. At this time, the amorphous phosphor is entirely crystallized, and strong impurities are removed through the removal of impurities and high reactivity of the raw material The aggregated powder-type inorganic phosphor has more excellent color rendering property and luminous efficiency, and therefore, the particle size of the inorganic phosphor produced by the solid-phase reaction method is not uniform and amorphous.

The amorphous inorganic phosphor is a resin-free inorganic substance, which is composed of a phosphor. Therefore, it has good durability, long lifetime at high temperature and high humidity, high thermal stability, high reliability at high temperature and high physico-chemical stability. Even with the phosphor of the same composition, the color temperature and the color coordinate can be adjusted through the thickness control, and the degree of freedom of color expression is high.

The inorganic phosphor is composed of a matrix made of an inorganic material and an activator ion, and a sulfide-based, an oxide-based, a nitride-based, an oxynitride-based, etc., depending on an anion constituting the matrix. As the LED becomes higher in output, oxides such as oxynitrides and nitride phosphors which are excellent in thermal stability and durability have been mainly applied.

The amorphous yellow inorganic phosphor may be contained in an amount of 0.5 to 2.5 parts by weight based on 100 parts by weight of the plastic resin. When the amorphous yellow inorganic phosphor is used in an amount of 0.5 part by weight or more, it is possible to achieve light emission with a desired longer wavelength. When the amorphous yellow inorganic phosphor is used in an amount of 2.5 parts by weight or less, color gamut is improved, It is possible not only to improve the image quality but also to improve the image quality through a wider viewing angle.

(2-3) Other components

The diffusion layer of the present invention may contain a filler, a heat curing agent, a UV curing agent, a curing accelerator, a coupling agent, a photoacid generator, an antioxidant, a surfactant, a radical initiator, a solvent and a mixture thereof.

The filler may be an organic polymer filler comprising a material selected from the group consisting of hard acrylate, polystyrene, nylon, soft acrylate and silicone. Of these, hard acrylate having good solvent resistance and easy dispersion is preferable. The filler is preferably spherical, and may have an average particle diameter of 0.5 to 5 mu m, preferably 0.8 to 3 mu m. The filler preferably has a refractive index different from the refractive index of the plastic resin by 0.02 or more. The filler may be used in an amount of 40 to 80 parts by weight, preferably 50 to 60 parts by weight, based on 100 parts by weight of the plastic resin constituting the diffusion layer.

The thermosetting agent is not particularly limited as long as it can be used for thermosetting a thermosetting resin, and examples thereof include an amine type curing agent, an acid anhydride type curing agent, an imidazole type curing agent, a carboxylic acid type curing agent, an organic acid hydrazide type curing agent, A curing agent, a polyol curing agent, an oxazoline curing agent, a melamine curing agent, or a mixture thereof.

The UV curing agent is not particularly limited as long as it can be used for curing a UV curing resin. Examples of the UV curing agent include triarylsulphonium hexafluoroantimonide, triarylsulfonium hexafluoroantimonate, triarylsulfonium hexafluorophosphate, And a cationic photoinitiator such as diaryl indonium salt.

As the curing accelerator, any of those capable of performing the function of promoting the reaction between the thermosetting resin and the thermosetting agent can be used, and examples thereof include an imidazole-based curing accelerator, a phosphine-based curing accelerator, an ammonium-based curing accelerator, And mixtures thereof.

Examples of the coupling agent include a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, and a silicone compound. These coupling agents may be used singly or in combination.

Examples of the antioxidant include phenol-based, sulfur-based, and phosphorus-based antioxidants. The antioxidant may be used to improve the heat stability of the cured product by preventing oxidation deterioration during thermal curing of the thermosetting resin composition.

The surfactant as the predetermined length of the hydrocarbon group and a small number -COONa, -OSO ₃ anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, Sulphonates (sulfonate) the hydrophilic group of Na as a compound having in the molecule in the molecule, Sulfates (sulfates, sulfuric acid ester salts), and ethoxylates (ethoxylates). These surfactants can be used alone or in combination.

The radical initiator is a compound that generates a radical in the presence of a monomer, and examples thereof include an organic peroxide, a hydroperoxide, an alkyl compound, and an azo compound. These radical initiators may be used singly or in combination.

The solvent is compatible with the above-described plastic resin and does not react with the plastic resin, and any known solvent used in the resin composition can be used. Examples of such a solvent include methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, butyl acetate or cyclohexanone. These solvents may be used alone or in combination of two or more.

2 shows a cross section of a diffusion sheet according to an embodiment of the present invention.

Referring to FIG. 2, a diffusion sheet according to an embodiment of the present invention includes a base layer 100 and a diffusion layer 200, and the diffusion layer 200 includes amorphous yellow inorganic phosphor 300.

On the other hand, the present invention provides a backlight unit including the aforementioned diffusion sheet. In addition, the present invention provides an LCD TV including the backlight unit. The backlight unit and the LCD TV including the backlight unit are widely known in the prior art, and thus a detailed description thereof will be omitted.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

Example  One

Amorphous yellow inorganic phosphor having a minimum particle diameter of 0.01 占 퐉 and a maximum particle diameter of 20 占 퐉 (100 parts by weight) was added to 100 parts by weight of a vinyl-based copolymer resin (Aekyou Chemical Co., Ltd., acrylic copolymer A-811) 0.5 part by weight of Nitride yellow coloring agent (MCC), 200 parts by weight of PMMA acrylic organic filler and 400 parts by weight of a mixed solvent of toluene and cyclohexanone (60:40 v / v).

The prepared resin composition was applied to a transparent polyethylene terephthalate film (V7200, SKC Co., Ltd.) having a thickness of 188 占 퐉 as a substrate layer by a wet coating method to form a diffusion layer having a thickness of 15 占 퐉, Followed by curing by heating at a temperature of 100 占 폚 to prepare a diffusion sheet.

Example  2

A diffusion sheet was prepared in the same manner as in Example 1, except that 1 part by weight of an amorphous yellow inorganic phosphor (dye for nitrogen dye, MCC) was used.

Example  3

A diffusing sheet was prepared in the same manner as in Example 1, except that 1.5 parts by weight of an amorphous yellow inorganic phosphor (dye for Nitride Yellow, MCC Co.) was used.

Example  4

A diffusion sheet was prepared in the same manner as in Example 1, except that 2 parts by weight of an amorphous yellow inorganic phosphor (pigment for use in Nitride Yellow, MCC) was used.

Example  5

A diffusion sheet was prepared in the same manner as in Example 1, except that 2.5 parts by weight of amorphous yellow inorganic phosphor (pigment for use in Nitride Yellow, MCC) was used.

Comparative Example  One

100 parts by weight of a vinyl-based copolymer resin (Aikyung Chemical Co., Ltd., acrylic copolymer A-811) having a (meth) acrylate as a main component were mixed with 200 parts by weight of PMMA acrylic organic filler, a mixed solvent of toluene and cyclohexanone 40 v / v) were mixed to prepare a resin composition. The prepared resin composition was applied to a transparent polyethylene terephthalate film (V7200, SKC Co., Ltd.) having a thickness of 188 占 퐉 as a substrate layer by a wet coating method to form a diffusion layer having a thickness of 15 占 퐉, Followed by curing by heating at a temperature of 100 占 폚 to prepare a diffusion sheet.

Comparative Example  2

A diffusing sheet was prepared in the same manner as in Example 1, except that 3.0 parts by weight of amorphous yellow inorganic phosphor (dye for use in Nitride Yellow, MCC) was used.

Experimental Example

One sheet of each diffusion sheet prepared in Examples 1 to 5 and Comparative Example 1 was placed on an Edge LED V1 bar BLU lamp which was being driven, and the luminance and color coordinate values were measured using a conometer of Espec Co., Ltd. . In the case of luminance, the relative luminance of the diffusion sheets of Examples 1 to 5 was calculated with the luminance of the diffusion sheet of Comparative Example 1 as a reference (100%).

The measurement results are shown in Table 1.

division Yellow phosphor Relative luminance x X y Y Comparative Example 1 0 100.00% 0.30414 - 0.28764 - Example 1 0.5 99.80% 0.31072 0.00658 0.29968 0.01204 Example 2 1.0 101.89% 0.31434 0.0102 0.30624 0.01860 Example 3 1.5 100.57% 0.31854 0.0144 0.31374 0.02610 Example 4 2.0 100.37% 0.32178 0.01764 0.31950 0.03186 Example 5 2.5 99.98% 0.32462 0.02048 0.32450 0.03686 Comparative Example 2 3.0 95.90% 0.33154 0.02740 0.33224 0.04460

As shown in Table 1, when the diffusion sheets of Examples 1 to 5 were used, the color of the yellow series was increased as compared with the diffusion sheet of Comparative Example 1. [

The results show that by adding an amorphous yellow inorganic phosphor to the diffusion layer, the yellow intensity can be enhanced to enhance the color reproducibility. The improved color reproducibility (Color Gamut) not only improves color sharpness, brightness, but also improves picture quality through a wider viewing angle.

10: blue LED light source 20: reflective sheet
30: light guide plate 40: condensing sheet
50: condensing sheet 60: diffusion sheet
100: base layer 200: diffusion layer
300: amorphous yellow inorganic phosphor

Claims (11)

A diffusion sheet comprising a base layer and a diffusion layer,
Wherein the diffusion layer is made of a plastic resin and 1.0 to 2.0 parts by weight of a (La, Y) ₃ Si ₆ N ₁₁ : Ce phosphor in an amount of 1.0 to 2.0 parts by weight based on 100 parts by weight of the plastic resin, 0.0 > 2 < / RTI > or greater,
Wherein the amorphous yellow inorganic phosphor has a particle size of 0.01 to 20 탆,
The thickness of the diffusion layer is 10 to 15 mu m,
Wherein the diffusion sheet has a thickness of 25 to 320 占 퐉.
The method according to claim 1,
Wherein the base layer is a polyester resin, an acrylic resin, a polycarbonate resin, a vinyl chloride resin, or a poly (meth) acrylamide resin.
The method according to claim 1,
Wherein the plastic resin is a thermosetting resin.
The method of claim 3,
Wherein the thermosetting resin is a phenol resin, an epoxy resin, an unsaturated polyester resin, an amino resin, or a mixture thereof.
The method according to claim 1,
Wherein the amorphous yellow inorganic phosphor absorbs light of a blue wavelength and emits light having a longer wavelength.
delete delete The method according to claim 1,
Wherein the diffusion layer is formed on the base layer by a wet coating method.
delete A backlight unit comprising the diffusion sheet of claim 1.
An LCD TV comprising the backlight unit of claim 10.

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