WO2014119899A1 - Optical film comprising light-emitting material, and backlight unit comprising same - Google Patents

Abstract

The present invention relates to an optical film comprising one or more sheets of film provided with a transparent substrate and a plurality of prisms arrayed thereon, wherein one or both of the transparent substrate and the prisms comprise light-emitting material, and the comparative light-emission peak is approximately 0.9 or lower in a wavelength band of approximately 380-480nm. The optical film is characterized by having superb intensity without a reduction in the refractive index and a wide viewing angle.

Description

 【Specification】

 [Name of invention]

 Optical film containing a light emitting material and a backlight unit including the same

 The present invention relates to an optical film and a backlight unit including the same. Background Art

 In the liquid crystal display (LCD), the performance of the image display means using the optical film is greatly affected by the performance of the back-light unit. This is because the basic method is to adjust the amount of light by reflecting or transmitting light through the optical film.

 Various optical films with excellent optical performance have been proposed for effective application to image display means. The prism sheet of the optical film is a film for improving the brightness of the liquid crystal display (LCD). Liquid crystal displays (LCDs) cannot emit light by themselves, so they use light sources (CCFLs or LEDs) to obtain light, distribute the light through the light guide plate over the entire area, and use diffuser sheets to provide more uniform brightness. Transform into a light source. In this process, the efficiency of light emitted from the initial light source is gradually reduced. The prism sheet can increase side brightness by converting side light into front light and focusing reflected light.

As such, the prism sheet as the light collecting sheet is an optical film having a thin film flexibility, and serves to increase the brightness by forming an optical pattern structured in a linear arrangement of prism shapes on one surface. However, the prism-shaped optical sheet has a problem in that the horizontal viewing angle is not good because of the sidelobe light loss, which is a structural problem of the prism shape, as compared to the lenticular-shaped optical sheet. At present, various types of film development have been attempted to solve this problem. The higher the refractive index, the better the performance of the prism film can achieve a high luminance. As a high refractive index resin conventionally used, bromine-substituted epoxy resins are frequently used. For example, acrylic acid is added to tetrabromo bisphenol A type epoxy resin and bisphenol A type epoxy resin, and styrene, The epoxy resin manufactured by mixing divinylbenzene, benzyl methacrylate, etc. is used.

 . However, the epoxy resin still exhibits a low refractive index of 1.590. In addition, Abesu number was low as 32, so there was much room for improvement for optics. In addition, the halogen-based resin may cause toxic carcinogens such as polyhalogenated aromatic dioxin or polyhalogenated dibenzofuran (1> 0 ^ 11310 ∞ ^ 6 (1 dibenzofuran) during combustion. There was a problem that gases generated during combustion, such as hydrogen chloride, adversely affect the human body and the environment.

 In addition, an optical material having a urethane bond or a thiocarbanic acid S-alkyl ester bond polymerized by adding an internal mold release agent to a mixture with an active hydrogen compound containing an aromatic polyisocyanate, a polyol, and a polythiol containing sulfur atoms was developed. It is becoming. However, there is a problem that the optical product is partially deformed during hard coating due to low thermal stability.

[Detailed Description of the Invention]

 [Technical problem]

 An object of the present invention is to provide an optical film having improved brightness without changing the refractive.

 Another object of the present invention is to provide an optical film having an improved horizontal viewing angle.

 Another object of the present invention is to provide an optical film that can increase the efficiency of the light source.

 The above and other objects of the present invention can be achieved by the present invention described below.

Technical Solution

One aspect of the invention is a transparent substrate; And at least one film provided with a plurality of prisms arranged on the transparent substrate, wherein the transparent substrate and the At least one of the prisms includes a luminescent material and relates to an optical film having a relative emission peak intensity of about 0.9 or less in a wavelength band of about 380 nm to about 480 nm. Another aspect of the invention relates to a backlight unit comprising the optical film.

 Another aspect of the invention the first optical film; And a second optical film provided above or below the first optical film, wherein the first optical film comprises a transparent substrate; And at least one film having a plurality of prisms arranged on the transparent substrate, wherein at least one of the transparent substrate and the prism includes a light emitting material and has a relative emission peak in a wavelength band of about 380 nm to about 480 nm. The intensity is about 0.9 or less, and the second optical film relates to a composite optical film including at least one optical pattern of a prism, a lenticular lens, a micro lens, and a rough shape on a transparent substrate.

Advantageous Effects

 The optical film of the present invention is excellent in luminance without lowering the refractive index and has an improved horizontal viewing angle without side-lobe light loss.

[Brief Description of Drawings]

 1 illustrates a cross-sectional photograph of a prism acid according to one embodiment of the present invention.

 2 is a conceptual diagram for explaining the radius of curvature of the prism and the height of the prism peak.

 3 is a perspective view of a backlight unit according to an embodiment of the present invention.

 4 illustrates a perspective view of a composite optical film according to an embodiment of the present invention.

5 is a graph showing the horizontal viewing angles of Examples 1-2 and Comparative Examples 1-3. 6 is a graph showing the vertical viewing angles of Examples 1-2 and Comparative Examples 1-2. 7 is a graph showing emission peaks according to emission wavelength bands of Examples 1 and 3. FIG. 8 is a graph showing emission peaks according to emission wavelength bands of Examples 2 and 4. FIG.

[Best form for implementation of the invention]

 1 is a cross-sectional photograph of a prism mountain according to an embodiment of the present invention, Figure 2 is a conceptual diagram for explaining the curvature radius of the prism and the height of the prism mountain. Hereinafter, an optical film according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

 An optical film according to an embodiment of the present invention includes a transparent substrate and a prism acid arranged on the transparent substrate.

 The prism mountain may be arcuate in shape. FIG. 1A illustrates a cross-sectional photograph of a prism mountain according to an embodiment of the present invention, and illustrates a case in which the government of the prism mountain is rounded in an arch shape. The prisms of the prism mountain can be rounded to form an arch to secure a wide horizontal viewing angle.

 At least one of the transparent substrate and the prism acid may include a light emitting material. The light emitting material described below may be introduced into at least one of the transparent substrate and the prism acid to ensure excellent luminance.

The light emitting material is at least one of a fluorescent material and a phosphor, and the light emitting material absorbs light in a specific region of the light source, thereby improving the brightness of the optical film without using a high refractive index resin, thereby replacing the high refractive index resin. Can be. The light emitting material may include a material having an emission characteristic by being excited by the emission wavelength band of the CCFL or LED lamp used as a light source in the backlight unit. The light emitting material may absorb energy in a blue region or an ultraviolet wavelength region and emit energy in a green region. Specifically, the light emitting material may have an absorption wavelength of about 240 nm to about 380 nm or about 420 nm to about 480 nm, and the emission wavelength may be about 520 nm to about 580 nm. Absorption wavelengths and emission wavelengths were measured in THF, CH ₂ C1 ₂₎ or their mixed solvents at low concentrations (usually 0.02 g / 100 ml samples on a sample basis ₎ .

The type of light emitting material included in the optical film may vary depending on the type of light source of the backlight unit including the optical film. Because the light from the light source of the backlight unit is reflected or transmitted through the optical film, the amount of light Because it is controlled. As a light source of the backlight unit, an LED lamp or CCFL may be used.

 When the light source in the backlight unit is an LED lamp, the light emitting material absorbs energy in the blue region and emits energy in the green region. The light emitting material has an absorption wavelength of about 420 nm to about 480 nm and an emission wavelength of about 520 nm to about 580 nm. This can be used.

 In the backlight unit, when the light source is CCFL, the light emitting material absorbs energy in the ultraviolet wavelength region and emits energy in the green region, and emits light having an absorption wavelength of about 240 nm to about 380 nm and an emission wavelength of about 520 nm to about 580 nm. Materials can be used.

 The optical film according to an embodiment of the present invention including the light emitting material may have a relative emission peak intensity of about 0.9 or less in an emission wavelength band of about 380 nm to about 480 nm, and about 1.1 or more in an emission wavelength band of about 520 nm to about 580 nm. have. In the present invention, the relative emission peak intensity is a parameter normalized to the emission peak intensity of the LED lamp light source, and means a value representing the emission peak intensity of the optical film including the light emitting material relative to the emission peak intensity of the LED lamp light source.

 The luminescent material may be an organic fluorescent or phosphorescent material, or an organic-inorganic hybrid fluorescent or phosphorescent material. The organic-inorganic hybrid fluorescent or phosphorescent material means a light emitting material in which an organic component and an inorganic component are simultaneously included in one material.

 Inorganic fluorescent or phosphorescent materials may absorb only certain regions of R, G, and B in the light of a light source, such as an LED lamp. Therefore, in order to improve light source efficiency, a plurality of inorganic fluorescent materials must be used to compensate for wavelength absorption for each of R, G, and B. However, when a plurality of inorganic fluorescent substances are included in the resin, there is a problem in dispersibility and color coordinate uniformity. On the other hand, the organic light emitting material may exhibit a wavelength absorption complementary effect on R, G, and B alone.

The fluorescent substance may include one or more of coumarin derivatives, pyran derivatives, quinacridone derivatives, aminoanthracene derivatives, naphthacene derivatives, phenylene vinylene, fluorene derivatives, naphthalene vinylene peri-naphthalene. Specifically,

 2,3,6,7-Tetrahydro-l, l, 7,7, tetramethyl-lH, 5H, llH-10- (2-benzothiazolyl) quin olizino [9,9a, lgh] coumarin (Product name C545T) One),

3- (2 '-benzo thi azo 1 y 1) -7-N, Nd iet hy 1 am i no coumarin (coumarin 6) (Formula 2), 4- (Di cyanome t hy 1 ene) -2-tert 一but y l-6- (l, 1,7,7-tetr ame t hy 1

julol idin-4-yl-vinyl) -4H-pyran (E) ， Ν, Ν 'ᅳ Dimethy 卜 quinacr idone (

DMQAK Formula 3), 9,10-bis [N, N-di- (p-tolyl) -ainino] anthraceiie (Product Name TTPA) (Formula 4), 9,10-bis [phenyl (m-tolyl) -aiTiino] anthracene (product name

TPA) (Formula 5), (5,6,11,12) -tetraphenylnaphthacene ((5,6,11,12) -Tetraphenylnaphthacene, product name Rubrene) (Formula 6), PPV (poly (p ᅳ phenylene vinylene )) (Formula 7), Polyf luorene, poly (naphthalene vinylene) (PNV), poly per i-naphthalene (PPN) or a combination thereof.

The phosphor may comprise a pyridine iridium derivative. Specifically, Tris [2- (p-tolyl) pyridine] iridium (III); Ir (mppy) 3) (Formula 8), Ir (piq) 3 (Formula 9), Bis [3,5-dif luoro-2- (2-pyr idyl) phenyl- (2-carboxypyr idyl) iridium (III) (^ l ^ ^T ¾ FlrPicK Formula 10), Tris (2-phenylpyridine) iridium (III)

Ir ( _PP y) 3) (Formula 11) or a combination thereof.

 <Formula 1>

 <Formula 2>

<Formula 3>

<Formula 6>

<Formula 7>

 (n is an integer of 100 to 500)

<Formula 11>

The light emitting material may include an ultraviolet curable unsaturated functional group. The ultraviolet curable unsaturated functional group may be a vinyl group or the like, but is not limited thereto. When the UV curable unsaturated functional group is included, the UV curable unsaturated compound and the curing reaction are performed to improve the strength and durability of the optical film together with the brightness improving effect.

The luminescent material may be included in about 0.001 percent by weight to about 0.5 weight ¾ of the optical film, such as about 0.001 percent by weight to about 0.1 weight ¾. Within this range, there may be a brightness synergistic effect. ^'

 The luminescent material may be included in about 0.001 weight ¾ to about 0.5 weight percent of the transparent substrate, for example, about 0.001 weight to about 0Λ weight ¾. Within this range, there may be a brightness synergistic effect.

 The luminescent material may be included in about 0.001% to about 0.5% by weight, such as about 0.001% by weight to about 0.1% by weight of the prism acid. Within this range, there may be a brightness synergistic effect.

 The prism acid may be a cured product of the resin composition including the light emitting material. The resin composition may further include an ultraviolet curable unsaturated compound, an initiator, and the like. In particular, UV-curable unsaturated compounds, fluorene derivative unsaturated resins, phenoxybenzyl (meth) acrylate, phenylphenoxyethyl (meth) acrylate, ethoxylated thiodiphenyl di (meth) acrylate, phenylthioethyl

By including (meth) acrylate monomers or their oligomers, It is possible to improve the adhesion and to improve the surface hardness of the prism acid. As the prism acid moves away from the light source, the concentration of the light emitting material may increase.

 The transparent substrate may be a glass film, a transparent synthetic resin, or the like as a transparent resin film. Generally, a transparent synthetic resin containing a polyethylene terephthalate material or the like can be used. The thickness of the transparent substrate may be about 30 to about 300.

 The prism acid according to one embodiment of the present invention may have an arch-shaped cross section with a radius of curvature of about 1 to about 35 / zm. For example, from about 10 to about 20

It may have an arch-shaped cross section which is IM.

 FIG. 1 (a) is a photograph of a cross section of a film including a curvature prism acid having a curvature radius of about 15 /, and FIG. 1 (b) is a photograph of a cross section of a film having a lenticular shape with a curvature radius of about 20 One picture.

 Referring to FIG. 2, the radius of curvature refers to a radius of a circle inscribed simultaneously on an isosceles except for the base of a triangle, which is a cross section of a prism. When the radius of curvature is 0, the prism peak has a sharp original cross-sectional shape. The larger the radius of curvature, the larger the roundness of the prism mount, but the lower the height of the prism mount.

 In the present invention, it is advantageous in the aspect of the prism mountain to have a curved cross section having a radius of about 1 to about 35! M, for example, about 10 to about 20, in terms of securing front luminance and horizontal viewing angle. The prism acid has a base length of about

25 to about 60 prn, and a height of about 12.5 μτη to about 30; The prism acid in the above range is excellent in characteristics such as brightness, but there is no problem such as moire. The transparent substrate and the prism acid may be integrally formed.

In another aspect of the present invention, the backlight unit may include the optical film. As an embodiment, referring to FIG. 3, the backlight unit 10 according to an embodiment of the present invention includes a light source 11, a light guide plate 12, and a light guide plate 12 that guide light emitted from the light source 11. ) Of the reflective sheet 13 disposed below the light guide plate, the diffusion sheet 14 disposed above the light guide plate 12, the optical film 15 disposed above the diffusion sheet 14, and the optical film 15. It may include a protective sheet 16 disposed on the top. In addition, the light source cover 11a may be disposed outside the light source 11 of the backlight unit. Also, Although not shown here, a liquid crystal display panel and an antireflection layer are sequentially stacked on the backlight unit 10 to form a liquid crystal display device. The light source 11 generates light, and various light sources such as a line light source lamp or a surface light source lamp, CCFL, or LED may be used.

 The light guide plate 12 guides the light generated by the light source 11 to the diffusion sheet 14, and may be omitted when a direct type light source is adopted.

 The reflective sheet 13 serves to reflect the light generated from the light source 11 and to supply it in the direction of the diffusion sheet 14.

 The diffusion sheet 14 diffuses and scatters light incident through the light guide plate 12 to supply the prism sheet 15.

 The optical film 15 refracts light incident through the diffusion sheet 14 to condense light onto a plane of a liquid crystal display panel (not shown). Optical film can be modified and combined with various design values such as the shape of the light collector and the angle of the slope of the light collector according to various design goals such as high light collection efficiency, wide viewing angle, prevention of moiré phenomenon, and prevention of optical wet out with Dalon film. And commercially applicable.

 In the present invention, the optical film may be configured by combining one or more sheets. As an example, an optical film may be further provided above or below the optical film.

 That is, transparent substrate; And a prism acid arranged on the transparent substrate, wherein at least one of the transparent substrate and the prism acid includes a light emitting material, wherein the prism acid has an arch shape having a radius of curvature of about 1 / to about 35 / ffli. When the optical film according to an embodiment of the present invention having a cross section is called a first optical film, a second optical film having the same or vertical direction as the first optical film is provided in the same direction as the first optical film. Can be.

In addition, a second optical film including one or more optical patterns of a prism, a lenticular lens, a micro lens, and a umber shape may be further provided on or below the first optical film. As an example, Figure 4 is a combination provided with a second optical film having a micro lens pattern on the optical film upper layer according to an embodiment of the present invention. [Form for implementation of invention] Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention. Example

 Specific specifications of the components used in the following Examples and Comparative Examples are as follows. (A) Luminescent material:

 9,1 Ibis [phenyl (m-lryl) -amino] anthracene of formula (4)

292.458 nm (in CH ₂ C1 ₂ ), photoluminescence wavelength: 532 nm (in CH ₂ C1 ₂ ))

 (B) UV curable unsaturated compound:

 (B1) fluorene derivative unsaturated resin (BPF-022, thickening, refractive index: 1.601)

(B21) phenoxybenzyl acrylate (refractive index: 1.56)

 (B22) Phenylphenoxyethyl acrylate (refractive index: 1.54)

 (C) initiator:

 (CI) Irgcure 184

 (C2) Iragacure TPO Examples 1-6 and Comparative Examples 1-5

 The resin composition for an optical film having the composition of Table 1 and Table 2 was prepared according to the following optical film manufacturing method, and the radius of the radius of prism acid was 2 sheets as shown in Table 3 below (lower film ®: bottom, upper film ① : After placing the optical film of the top) perpendicular to the prism acid array direction and the physical properties measured according to the measurement method shown in Table 3 below.

Table 1

 [Unit: weight%]

[Table 2]

 [Unit: weight «Optical film manufacturing

The resin composition for an optical film prepared above was applied to a metal mold having a prism layer imprinted thereon, and one side of the transparent base PET film (polyethylene terephthalate film) was in contact with the coating surface applied to the metal mold. UV light of 400 nm wavelength was mounted on an electrodeless ultraviolet irradiation device (600W / inch) with a Type-D bulb and irradiated with energy of 250 mJ / cin ² to 500 mJ / cirf) to cure the coated composition. . By separating the cured coating layer adhered to the transparent substrate film from the metal mold, an optical film having a prism layer formed on one surface of the transparent substrate film was prepared. The height of the optical film layer was set to 35-40. Property measurement method

 (1) Refraction: The refractive index of the optical films prepared in Examples and Comparative Examples was measured using a refractometer (Model: IT, Japan ATAGO ABBE). A light source for the measurement was a D-beam sodium lamp of 589.3 nm.

 (2) Luminance: Fix the above-mentioned prism film to a 32-inch liquid crystal display panel backlight unit, and measure the average value by measuring the luminance at 13 points and 5 points using a luminance meter (Model name: SR3, Japan TOPCON Co., Ltd.). It was. In this case, an LED lamp was used as a light source of the backlight unit. The brightness | luminance was shown in% based on the brightness | luminance of the optical film which has a structure which laminated | stacked 60 MLA sheets of diameter into two layers.

 (3) Viewing angle: The viewing angle was also measured using the same equipment as the luminance equipment while applying the inclination (0 ° to 180 °). In this case, an LED lamp was used as a light source of the backlight unit. The horizontal viewing angles of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in the graph of FIG. 5, and the vertical viewing angles of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in the graph of FIG. 6.

(4) Relative emission peak intensity: For each of the prism sheets prepared in Examples and Comparative Examples, the emission peaks were measured with a measuring device (model name: CS-2000, TOPCON, Japan) using a measuring device (Model name: CS-2000, Japan TOPCON Co., Ltd.). 7 and 8 are shown. FIG. 7 shows light emission peaks measured using an LED lamp light source having a maximum light emission peak of about 3.0E-0.2 (au) measured by the device in the light emission wavelength band of 380 nm to 480 nm, and FIG. 8 shows a light emission peak of 380 nm to 480 nm. The emission peak was measured using an LED lamp light source having a maximum emission peak of about 2.5E-0.2 (au) when measured by the device in the nm emission wavelength band. [Table 3]

As shown in Table 3, Comparative Examples 1 to 3 containing no light emitting material did not have good brightness, and in Comparative Example 4 in which the prism structure was not formed, the viewing angle was not good.

 In addition, Figure 7 is a graph showing the emission peak according to the emission wavelength band of Example 1 and Example 3, Figure 8 is a graph showing the emission peak according to the emission wavelength band of Example 2 and Example 4, Figure 7 8, the optical films of Examples 1 to 4 including a light emitting material and having a curvature prism structure have a relative emission peak intensity of 0.9 or less in an emission wavelength band of 380 nm to 480 nm, and in an emission wavelength band of 520 nm to 580 nm. It turns out that it is 1.1 or more. Ref. Is the emission peak of the LED lamp light source itself, and in Comparative Examples 1 and 2, Ref. And the emission peak are substantially the same, and are not separately shown.

 Simple modifications and variations of the present invention can be easily made by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims

[Range of request]

 [Claim 1]

 Transparent substrate; And

 At least one film having a plurality of prisms arranged on the transparent substrate;

 At least one of the transparent substrate and the prism includes a light emitting material, and the relative emission peak intensity in the wavelength band of about 380nm to about 480nm, characterized in that less than about 0.9. [Claim 2]

 The method of claim 1,

 An optical film having a relative emission peak intensity in the wavelength band of about 520 nm to about 580 nm of about i ᅳ i or more. [Claim 3]

 The method of claim 1,

 The prism acid of the prism has an arch-shaped cross section with a radius of curvature of about 1 kPa to about 35 / mi. [Claim 4]

 The method of claim 1,

 The light emitting material is an optical film, characterized in that at least one of a fluorescent material and a phosphorescent material. [Claim 5]

 The method of claim 1,

The luminescent material comprises an ultraviolet curable functional group. [Claim 6] The method of claim 4,

 The fluorescent material is 2,3,6-Tetrahydro-l, l, 7,7, tetramethyl-; LH, 5H, HH-10- (2-benzothiazolyl) quinol izino [9,9a, lgh] coumarin,

3- (2'-benzothiazolyl) -7-N, N-di ethyl ami no coumarin,

4- (Dicyanomethylene) -2-tert-butyl-6- (l, l, 7,7-tetramethylejulolidin-4-yl-vin yl) -4H-pyran (E), Ν, Ν'-Dimethyl-quinacridone, 9 ， 10 一 bis [N, N— di 一 (p_tolyl) -ami no] anthracene,

 9, 10 bis [phenyl (m-tolyl) _amin is anthracene, 5,6, 11, 12-Tetraphenylnaphthacene PPV (po 1 y (-pheny 1 ene vinylene)), Polyf luorene, PNV (po ly (naphtha 1 ene vinylene) poly peri nanphthalene (PPN), or a combination thereof,

 The phosphors include Tris [2- (p-tolyl) pyridine] iridium (III), Bis [3,5-dif 1 uoro-2- (2-pyr idyl) heny 1― (2-carboxypyr idyl) iridium (III) ),

Tris (2-phenylpyridine) iridium (III) or an optical film thereof. [Claim 7]

 The method of claim 1,

 The light emitting material is an optical film, characterized in that included in about 0.001% to about 0.5% by weight of the optical film.

[Claim 8]

The method of claim 1 wherein the prism has a base length of about 25 urn to

And a height of about 12.5 to about 30 / zm.

[Claim 9]

 The method of claim 1,

 The transparent substrate and the prism is an optical film, characterized in that formed integrally.

[Claim 10]

A backlight unit comprising the optical film according to any one of claims 1 to 9. Claim Port HI

 A first optical film; And a second optical film provided above or below the first optical film.

 The first optical film is an optical film according to any one of claims 1 to 9, wherein the second optical film includes at least one optical pattern of a prism, a lenticular lens, a micro lens, and a gloss shape on a transparent substrate. Composite optical film, characterized in that.

[Claim 12]

 The method of claim 11,

The composite optical film has a brightness of about 90% or more, and a horizontal and vertical viewing angle of about 70 ^° or more, compared to a composite diffusion film in which two diffusion films having a diameter of about 60 microns are arranged on a transparent substrate. Composite optical film.