KR20160094888A - Color conversion film and method for preparing the same and back light unit comprising the same - Google Patents

Abstract

The invention described herein relates to a resin matrix; And an organic phosphor dispersed in the resin matrix and emitting light of a wavelength different from that of light absorbed by absorbing blue or green light, wherein the color conversion film comprises: (1) an N ₂ gas atmosphere at room temperature; Under the condition of 2) 60 and relative humidity of 90%, and 3) light emitted from a blue LED backlight having a maximum emission wavelength in the range of 440 nm to 460 nm at 60 is subjected to light irradiation , Wherein at least 90% of the initial luminance is maintained for 1,000 hours or more, a method for producing the same, and a backlight unit including the color conversion film.

Description

TECHNICAL FIELD [0001] The present invention relates to a color conversion film, a method of manufacturing the same, and a backlight unit including the same. BACKGROUND ART < RTI ID = 0.0 >

The present application relates to a color conversion film and a manufacturing method thereof, and a backlight unit including the color conversion film.

With the large-sized TV, high-definition, slimmer, and more sophisticated functions are being performed. High-performance, high-definition OLED TVs still have a problem of price competitiveness, and the market is not yet open. Therefore, efforts to secure similar advantages of OLEDs with LCDs are continuing.

The TV driving method using the conventional white LED backlight has a narrow color gamut. Therefore, in order to improve the color gamut, a study to secure a much wider color reproduction rate and color range with a film made by applying a quantum dot (Quantum Dot) .

However, since most of the quantum dots are vulnerable to oxygen and moisture in the air, there are many restrictions on their use. Therefore, a barrier film having water permeability and oxygen permeability of 10 ^-2 g / m ² * dy or less is adhered to both sides of the quantum dot film It is essential to do. Therefore, it is necessary to develop a film that is stable to moisture and oxygen while achieving a high color reproducibility and a wide color range.

The present application provides a color conversion film excellent in durability, a method for producing the same, and a backlight unit including the same.

One embodiment of the present application relates to a resin matrix; And an organic phosphor dispersed in the resin matrix and emitting light of a wavelength different from that of light absorbed by absorbing blue or green light, wherein the color conversion film comprises: (1) an N ₂ gas atmosphere at room temperature; 2) under the conditions of 60 ° C and relative humidity of 90%, and 3) light emitted from a blue LED backlight having a maximum emission wavelength in the range of 440 nm to 460 nm at 60 ° C, And 90% or more of the initial luminance is maintained for 1,000 hours or more under the condition of light irradiation.

According to an embodiment of the present invention, the organic fluorescent material includes an organic fluorescent material that emits light having a wavelength selected from 500 to 680 nm when light having an emission peak at a wavelength of 450 nm is irradiated.

According to an embodiment of the present invention, the organic phosphor has a maximum emission wavelength in the range of 500 to 680 nm when emitting light having an emission peak at 450 nm and a half width of 40 nm or less and a light intensity distribution of monomodal Containing organic phosphors.

According to another embodiment of the present application, the color conversion film further maintains 90% or more of the initial luminance for 1,000 hours or more under the condition of 85 캜 and 85% relative humidity.

Another embodiment of the present application provides a color conversion film characterized in that the color conversion film according to the above-described embodiment further comprises light diffusion particles.

In another embodiment of the present application, the color conversion film according to the above-described embodiment is a resin matrix material; And coating the solution containing the organic fluorescent substance on a substrate and drying the organic fluorescent substance, or by extruding the organic fluorescent substance together with the resin matrix material.

Another embodiment of the present application provides a backlight unit including the color conversion film.

The organic phosphors dispersed in the color conversion film according to the embodiments described herein have stable physical properties even under high temperature and / or high humidity conditions. Therefore, even if there is no separate water and / or oxygen interception, So that the color conversion film can exhibit the barrier property even without a separate barrier film. Therefore, unlike the quantum dot film in which a barrier film is provided on both sides and moisture and oxygen interception are required, the color conversion film described in this specification can maintain a stable physical property by itself without a barrier film.

1 and 2 show durability measurement results of the color conversion films prepared in Examples 1 and 2, respectively.
Fig. 3 compares the luminance of the color conversion film produced in Example 1 containing light diffusing particles and the color conversion film prepared in Example 3 and a separate light diffusion film.
Fig. 4 is a schematic view of applying a color conversion film to a backlight according to an embodiment of the present application. Fig.

A color conversion film according to one embodiment of the present application includes a resin matrix; And an organic phosphor dispersed in the resin matrix and emitting light of a wavelength different from that of light absorbed by absorbing blue or green light, wherein the color conversion film comprises: (1) an N ₂ gas atmosphere at room temperature; 2) under the conditions of 60 ° C and relative humidity of 90%, and 3) light emitted from a blue LED backlight having a maximum emission wavelength in the range of 440 nm to 460 nm at 60 ° C, And 90% or more of the initial luminance for 700 hours or more under the condition of light irradiation.

According to an embodiment of the present invention, the organic fluorescent material includes an organic fluorescent material that emits light having a wavelength selected from 500 to 680 nm when light having an emission peak at a wavelength of 450 nm is irradiated.

According to an embodiment of the present invention, the organic phosphor has a maximum emission wavelength in the range of 500 to 680 nm when emitting light having an emission peak at 450 nm and a half width of 40 nm or less and a light intensity distribution of monomodal Containing organic phosphors.

The color conversion film according to another embodiment of the present application is characterized by maintaining at least 90% of the initial brightness for 1,000 hours or more under the conditions of 1) to 3), 4) 85 ° C and 85% relative humidity .

According to the above-described embodiment, the color conversion film exhibits stable luminance characteristics at room temperature as well as under a high temperature and high humidity condition without a separate barrier film. Further, as in the above 4), the display device exhibits stable luminance characteristics for a long time even under actual TV driving conditions.

The color conversion film according to the above-described embodiments may be used without additional film because it has barrier properties under high temperature and / or high humidity conditions as well as at room temperature, but the scope of the present invention is not limited thereto. On one side, a barrier film can be laminated as required.

Since the organic phosphors used in the above-described embodiments have stable characteristics with respect to moisture and oxygen, they can exhibit stable luminance characteristics at high temperature and / or high temperature as well as at room temperature as in the above-described embodiment.

According to one embodiment, the half-value width of the light-emitting wavelength in the color conversion film is 60 nm or less. The half width refers to the width of the emission peak when the maximum emission peak of the light emitted from the film is half the maximum height. The half width of the emission peak in this specification can be measured in the film state. The light emitted to the film at the half-width of the film may be a light having an emission peak at 450 nm and a half-width of 40 nm or less and a light intensity distribution of monomodal. The half width of the emission peak may be determined by the type and composition of components such as the organic phosphor, the resin matrix or other additives contained in the color conversion film. The smaller the half width of the emission peak of the color conversion film, the better the color reproduction rate is.

According to one embodiment of the present application, the organic phosphor may include an organic phosphor that absorbs blue or green light to emit red light, an organic phosphor that absorbs blue light to emit green light, or a mixture thereof .

In this specification, blue light, green light, and red light may be defined as those known in the art, for example, blue light is light having a wavelength selected from a wavelength of 400 nm to 500 nm, green light is 500 nm to 560 nm, and the red light is light having a wavelength selected at a wavelength of 600 nm to 780 nm. In this specification, a green phosphor absorbs at least a part of blue light to emit green light, and a red phosphor absorbs at least a part of blue light or green light to emit red light. For example, the red phosphor may absorb blue light as well as light having a wavelength between 500 and 600 nm.

According to one embodiment of the present invention, when the organic phosphor has an emission peak at 450 nm and a half width of 40 nm or less and a light intensity distribution of monomodal blue light, the maximum emission wavelength And an organic fluorescent material.

According to one embodiment of the present application, the organic phosphor may include an organic phosphor having a maximum emission wavelength in the range of 500 to 680 nm when light having an emission peak of 450 nm wavelength is irradiated.

According to one embodiment of the present invention, the organic fluorescent material may be a pyrromethene metal complex series or a perylene series dye. For example, the following materials may be used, but the following examples are limited only to the following examples It is not.

The content of the organic fluorescent material may be 0.001 to 10% by weight based on 100% of the entire color conversion film.

The material of the resin matrix is preferably a thermoplastic polymer or a thermosetting polymer. Specifically, examples of the material of the resin matrix include poly (meth) acrylate, polycarbonate (PC), polystyrene (PS), polyarylene (PAR), styrene- A nitrile series (SAN), a polyvinylidene fluoride series (PVDF), a modified polyvinylidene fluoride series (modified-PVDF), or the like can be used. According to one example, when polymethylmethacrylate (PMMA) and styrene-acrylonitrile (SAN) resin are used as the resin matrix material, the strength of the color conversion film in the above conditions (1) to (4) And transparent properties can be maintained.

According to another embodiment of the present application, the color conversion film according to the above-described embodiment further includes light diffusion particles. In order to improve the brightness, the light diffusion particles are dispersed in the color conversion film in place of the conventional light diffusion film, so that the adhering step can be omitted as compared with the use of a separate optical acid film, .

As the light-diffusing particles, resin matrices and particles having a high refractive index can be used. For example, TiO ₂ , silica, borosilicate, alumina, sapphire, air or other gas, air- or gas- filled hollow beads or particles , Air / gas-filled glass or polymer); Polymer particles including polystyrene, polycarbonate, polymethyl methacrylate, acryl, methyl methacrylate, styrene, melamine resin, formaldehyde resin, or melamine and formaldehyde resin, or any suitable combination thereof.

The particle size of the light-diffusing particles may be in the range of 0.1 micrometer to 5 micrometers, for example, in the range of 0.3 micrometer to 1 micrometer. The content of the light-diffusing particles can be determined as necessary, and can be, for example, within a range of about 3 to 30 parts by weight based on 100 parts by volume of the resin matrix.

The color conversion film according to the above-described embodiment may have a thickness of 2 to 200 micrometers. In particular, the color conversion film can exhibit high luminance even at a thin thickness of 2 to 20 micrometers. This is because the content of the organic fluorescent substance molecules contained in the unit volume is higher than that of the quantum dots. For example, even when the amount of the organic fluorescent material per unit volume of the color conversion film is about 0.02 - 20 탆 ol / cm ³ , the blue organic light emitting material is not less than 4000 nit in terms of the luminance of the blue backlight unit 600 nit, lt; RTI ID = 0.0 > nit. < / RTI >

The color conversion film according to the above-described embodiments may have a substrate on one side thereof. This substrate may serve as a support in the production of the color conversion film. The kind of the substrate is not particularly limited and is not limited to the material and thickness as long as it is transparent and can function as the support. Here, transparent means that the visible light transmittance is 70% or more. For example, a PET film may be used as the substrate.

The above-mentioned color conversion film can be produced by coating a resin solution in which an organic fluorescent material is dissolved and drying it, or extruding an organic fluorescent material together with a resin to form a film.

Since the organic fluorescent substance is dissolved in the resin solution, the organic fluorescent substance is homogeneously distributed in the solution. This is different from the manufacturing process of a quantum dot film requiring a separate dispersion process.

Additives may be added to the resin solution if necessary, and a light diffusion agent such as silica, titania, zirconia, and alumina powder may be added. Further, a dispersant may be further added for stable dispersion of the light-diffusing particles.

The resin solution in which the organic fluorescent substance is dissolved is not particularly limited if the organic fluorescent substance and the resin are dissolved in the solution.

According to one example, a resin solution in which an organic fluorescent material is dissolved is prepared by preparing a first solution by dissolving the organic fluorescent substance in a solvent, dissolving the resin in a solvent to prepare a second solution, and mixing the first solution and the second solution . ≪ / RTI > When the first solution and the second solution are mixed, it is preferable to mix them homogeneously. However, the present invention is not limited to this, but a method of dissolving an organic fluorescent substance and a resin in a solvent at the same time, a method of dissolving an organic fluorescent substance in a solvent followed by a dissolution by adding a resin, a method of dissolving a resin in a solvent, .

The organic fluorescent substance contained in the solution is as described above.

As the resin contained in the solution, the above-mentioned resin matrix material, a monomer curable with the resin matrix resin, or a mixture thereof can be used. For example, as the monomer curable with the resin matrix resin, there is a (meth) acrylic monomer, which can be formed from a resin matrix material by UV curing. In the case of using such a curable monomer, an initiator necessary for curing may be further added if necessary.

The solvent is not particularly limited and is not particularly limited as long as it can be removed by drying without adversely affecting the coating process. Non-limiting examples of the solvent include toluene, xylene, acetone, chloroform, various alcohol solvents, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), EA (ethyl acetate), butyl acetate, Cyclohexanone, PGMEA (propylene glycol methyl ethyl acetate), dioxane, DMF (dimethylformamide), DMAc (dimethylacetamide), DMSO (dimethylsulfoxide), NMP (N-methylpyrrolidone) And the like, and they may be used alone or in combination of two or more. When the first solution and the second solution are used, the solvent contained in each of these solutions may be the same or different. Even when different kinds of solvents are used for the first solution and the second solution, it is preferable that these solvents have compatibility so that they can be mixed with each other.

If necessary, light diffusing particles may be added to the resin solution. The step of dispersing the light-diffusing particles in the resin solution may be further performed. The light diffusion particles are as described above.

A roll-to-roll process can be used for the step of coating the resin solution on which the organic fluorescent material is dissolved on the substrate. For example, a step of dissolving a substrate from a roll on which a substrate is wound, coating a resin solution in which the organic fluorescent material is dissolved on one side of the substrate, drying the coated substrate, and then winding the coated substrate on a roll. In the case of using a roll-to-roll process, it is preferable to determine the viscosity of the resin solution within a range in which the process can be performed, and may be determined within a range of, for example, 200 to 2,000 cps.

As the coating method, various known methods can be used, for example, a die coater may be used, and various bar coating methods such as a comma coater, a reverse comma coater, and the like may be used.

After the coating, a drying process is performed. The drying process can be carried out under the conditions necessary for removing the solvent. For example, a color conversion film containing an organic phosphor of a desired thickness and concentration can be obtained on a substrate by drying the substrate in a direction in which the substrate proceeds in a coating process and in a state where the solvent is sufficiently blown in an oven located adjacent to the coater.

When a monomer curable with the resin matrix resin is used as the resin contained in the solution, curing such as UV curing may be performed before or during the drying.

When the organic fluorescent substance is extruded together with the resin to form a film, an extrusion method known in the art may be used. For example, the organic fluorescent substance may be used in combination with a polycarbonate (PC), a poly (meth) acrylic, a styrene-acrylonitrile (SAN) may be extruded together to prepare a color conversion film.

Another embodiment of the present application provides a backlight unit including the above-mentioned color conversion film. The backlight unit may have a backlight unit configuration known in the art, except that it includes the color conversion film. FIG. 4 shows a schematic diagram of a backlight unit structure according to an example. The backlight unit according to Fig. 4 includes a side-chain type light source (blue), a reflecting plate (green) surrounding the light source, a light guide plate (apricot) for directly emitting light from the light source or guiding light reflected from the reflection plate, And a color conversion film (white) provided on the opposite surface of the light guide plate opposite to the reflective layer. In Fig. 4, the gray portion is the light dispersion pattern of the light guide plate. The light introduced into the light guide plate has a non-uniform light distribution due to repetition of optical processes such as reflection, total reflection, refraction, and transmission, and a two-dimensional light dispersion pattern can be used to induce uniform brightness. The light dispersion pattern can guide the light introduced into the light guide plate to a uniform brightness by scattering the light. However, the scope of the present invention is not limited to that shown in FIG. 4. The light source may be a direct-type as well as a side-chain type, and a reflector or a reflective layer may be omitted or replaced with another structure if necessary, A light-diffusing film, a light-condensing film, a luminance improving film, and the like.

Hereinafter, the present invention will be described in more detail by way of examples.

Example  One

The phosphor of the following structure was dissolved in DMF (Dimethylforamide) to prepare a first solution.

SAN (Styrene-Acrylonitrile), a thermoplastic resin, was dissolved in DMF to prepare a second solution. The first solution and the second solution were mixed. In the mixed solution, the fluorescent material was 0.15 wt% of the resin and the solid content was 25 wt%. The viscosity of the mixed solution was about 400-1000 cP. To the mixed solution, 3 parts by weight of TiO ₂ particles having a particle diameter of about 400 nm were added to 100 parts by weight of the thermoplastic resin and mixed homogeneously. The mixed solution was coated on a PET substrate and dried to prepare a color conversion film.

The durability of the color conversion film thus produced was measured in a N ₂ gas atmosphere (condition 1) at room temperature, 60 ° C and a relative humidity of 90% (condition 2), emission at 60 ° C from a blue LED backlight having a maximum emission wavelength in the range of 440 nm to 460 nm (Condition 3), and 85 ° C and 85% relative humidity (condition 4). The results are shown in FIG. 1. 1, the vertical axis represents the luminance (nit) and the horizontal axis represents the time (hr). According to FIG. 1, it can be seen that more than 90% of the initial luminance was maintained stably for 1,400 hours.

Further, the color conversion film prepared in Example 1 was exposed for 1,000 hours under conditions 2, 3 and 80 ° C, respectively, and then irradiated with x, y The color coordinates are measured, and the differences of the x, y color coordinates from the reference not exposed to the above conditions are shown in Table 1 below.

Condition 2 Condition 3 80 ℃ Difference from Reference Δx Δy Δx Δy Δx Δy Example 1 3 / 10,000 4 / 10,000 -6 / 10,000 7 / 10,000 0 15 / 10,000

As shown in Table 1, when the conditions 1) to 4) were satisfied, the x and y chromaticity coordinates were also within 2 / 10,000.

Example  2

The procedure of Example 1 was repeated, except that the compound of the following structural formula was used as the phosphor. The durability of the color conversion film thus prepared was measured by the same method as in Example 1, and the results are shown in Fig. 2, the vertical axis represents the luminance (nit) and the horizontal axis represents the time (hr). According to FIG. 2, it can be seen that more than 90% of the initial luminance was maintained stably for 1,200 hours.

Example  3

The procedure of Example 1 was repeated except that no light diffusing material was added. The luminance of the color conversion film of Example 1 and the structure obtained by laminating a diffuser film on one surface of the color conversion film of Example 3 is shown in Fig.

The luminance was measured with a spectral radiance spectrometer (TOPCON SR series). Specifically, the color conversion film thus prepared was laminated on one side of a light guide plate of a backlight unit including an LED blue backlight (maximum emission wavelength of 450 nm) and a light guide plate, and two prism sheets and a DBEF film were laminated on the color conversion film The luminance spectrum of the post-film was measured. The initial value was set so that the brightness of the blue LED light was 600 nits when measuring the luminance spectrum.

3, Example 1 (luminance: 1400 nit) in which light diffusing particles were added inside a color conversion film without using a separate light diffusion film was used in the case where a separate light diffusion film was used without adding light diffusion particles The luminance was improved by about 112% as compared with the case where the luminance was 1250 nits).

Example  4

The procedure of Example 1 was repeated except that TiO ₂ as a light diffusing material was added in an amount of 3% by weight based on the entire color conversion film. The results of luminance measurement in the same manner as in Examples 1 and 3 are shown in Fig.

Example  5

The procedure of Example 1 was repeated, except that TiO ₂ was added as a light diffusing material in an amount of 1 wt% with respect to the entire color conversion film. The results of luminance measurement in the same manner as in Examples 1 and 3 are shown in Fig.

Comparative Example  One

A polyurethane resin was used in place of the SAN, and the same procedure as in Example 1 was carried out. The film thus produced turned yellow as time elapsed, indicating that the durability was poor.

Claims (8)

Resin matrix; And an organic phosphor dispersed in the resin matrix and emitting light of a wavelength different from that of light absorbed by absorbing blue or green light, wherein the color conversion film comprises: (1) an N ₂ gas atmosphere at room temperature; 2) under the conditions of 60 ° C and relative humidity of 90%; 3) light emitted from a blue LED backlight having a maximum emission wavelength in the range of 440 nm to 460 nm at 60 ° C, Wherein at least 90% of the initial luminance is maintained for 1,000 hours or more under the irradiation condition. The color conversion film according to claim 1, wherein the color conversion film maintains 90% or more of the initial luminance for 1,000 hours or more under the condition of 85 캜 and 85% relative humidity. The organic electroluminescent device according to claim 1 or 2, wherein the organic phosphor comprises an organic phosphor that absorbs blue or green light to emit red light, an organic phosphor that absorbs blue light to emit green light, film. The color conversion film according to claim 1 or 2, further comprising light diffusion particles. The color conversion film according to claim 4, wherein the light-diffusing particles comprise TiO ₂ . The color conversion film according to claim 1 or 2, wherein the color conversion film comprises a resin matrix material; And coating the solution containing the organic fluorescent material on a substrate, followed by drying, or extruding the fluorescent material together with the resin matrix material. A backlight unit comprising a color conversion film according to claim 1 or 2 A backlight unit comprising the color conversion film according to claim 4.

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