KR101951712B1

KR101951712B1 - Color conversion film and method for preparing the same

Info

Publication number: KR101951712B1
Application number: KR1020150117032A
Authority: KR
Inventors: 박태성; 안병인; 신동목
Original assignee: 주식회사 엘지화학
Priority date: 2015-08-20
Filing date: 2015-08-20
Publication date: 2019-02-25
Also published as: KR20170022266A

Abstract

A first color conversion layer including a resin matrix and a phosphor dispersed in the resin matrix and emitting light having a wavelength different from that of the irradiated light when light having a wavelength of 450 nm is irradiated; And at least a portion of the edge portion on at least one side of the first color conversion layer, the resin matrix being dispersed in the resin matrix and emitting light having a wavelength different from that of the irradiated light when irradiated with light having a wavelength of 450 nm A color conversion film including a second color conversion layer including a phosphor, and a backlight unit and a display device including the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a color conversion film,

The present application relates to a color conversion film and a method for producing the same.

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.

As one of the above efforts, many quantum dot related technologies and prototypes have recently been implemented. However, since the cadmium-based quantum dots have safety problems such as restriction of use, attention is focused on the manufacture of backlights using cadmium-free quantum dots without relative safety issues.

Korean Patent Application Publication No. 2000-0011622

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

One embodiment of the present application

A first color conversion layer including a resin matrix and a phosphor dispersed in the resin matrix and emitting light having a wavelength different from that of the irradiated light when irradiated with light having a wavelength of 450 nm; And

And a phosphor dispersed in the resin matrix and emitting light having a wavelength different from that of the light irradiated when the light having a wavelength of 450 nm is irradiated, at least a part of the edge portion on at least one side of the first color conversion layer And a second color conversion layer

And a color conversion film.

According to another embodiment of the present application, a transparent film is provided on at least one surface of the first color conversion layer. The transparent film is directly contacted to the first color conversion layer or attached through the adhesive layer.

According to another embodiment of the present application, a transparent film is provided on at least one surface of the second color conversion layer. According to one example, an adhesive layer is provided on a surface of the second color conversion layer opposite to the first color conversion layer, and a transparent film is provided on a surface opposite to the surface facing the first color conversion layer.

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

According to the embodiments described herein, the color conversion layer is further laminated on at least one edge of the color conversion layer, so that the blue color light is emitted from the edge of the color conversion layer due to total reflection in the color conversion layer It is possible to prevent a phenomenon that light is lost and the edge portion is bluish. This makes it possible to prevent the color of the center and the edge of the screen from becoming uneven when the display such as a TV is driven due to the blue coloring of the edge portion.

Figures 1-6 illustrate cross sections of color conversion films according to embodiments of the present application.
Figures 7 to 10 illustrate top views of color conversion films according to embodiments of the present application.
Figures 11-13 illustrate a backlight unit according to embodiments of the present application.
Fig. 14 is a schematic top view of the backlight unit shown in Fig. 13. Fig.
15 and 16 illustrate scattering patterns provided in the light guide plate of the backlight unit according to the embodiments of the present application.
Figures 17-19 illustrate a display device according to embodiments of the present application.

A color conversion film according to an embodiment of the present application includes a resin matrix and a first color conversion layer dispersed in the resin matrix and including a phosphor that emits light of a wavelength different from that of the emitted light; And a second color conversion layer provided on at least a part of the edge portion on at least one side of the first color conversion layer and including a resin matrix and a phosphor dispersed in the resin matrix and emitting light having a wavelength different from that of the irradiated light, . By forming the edge portion of the color conversion film in the double layer structure in this way, the wavelength of the blue light at the edge portion can be changed to prevent the blue phenomenon of light.

In the present specification, the edge refers to a portion extending from the edge line on one side of the first color conversion layer to a central portion with a constant width. The edge portion does not include the center portion of one surface including the edge portion of the first color conversion layer. According to one example, the edge portion may be arranged to have a width of 10% or less, for example, 5% or less of the width of the first color conversion layer in the direction perpendicular to the perimeter line from the edge line of the first color conversion layer have. In this specification, the width of the edge portion of the first color conversion layer can be used to have the same meaning as the width of the second color conversion layer. The width of the second color conversion layer may be constant or may have a different width depending on the position.

According to one embodiment, by including the above-mentioned second color conversion layer, a color conversion film is laminated on a light guide plate using a light source including blue light having a maximum wavelength of 445 nm and green light having a maximum wavelength of 535 nm When the emission spectrum is measured by the luminance meter, the deviation of u ', v' measured at intervals of 4 mm on an imaginary straight line on the color conversion film may be 0.01 or less, preferably 0.005 or less. Also, under the above conditions, the R / G ratio or the R / B ratio deviation may be 0.1 or less, more preferably 0.05 or less. A prism film and / or a brightness enhancement film may be further laminated on the color conversion film as needed for emission spectrum measurement. The deviation of u ', v', R / G ratio, and R / B ratio are not influenced by the lamination of the prism film and the brightness enhancement film. R / G or R / B ratio is calculated by calculating the ratio based on max intensity of each color.

According to one embodiment of the present application, when one surface of the first color conversion layer is a quadrangle, the second color conversion layer has an edge portion on one side of one side of the first color conversion layer, It may be provided at the edge portion of three sides or the edge portion of four sides. FIG. 1 and FIG. 2 illustrate a cross-sectional structure of a color conversion film according to an example. Fig. 1 shows an example in which a second color conversion layer is provided at an edge portion of one side, and Fig. 2 shows an example in which a second conversion layer is provided at an edge portion at opposite sides. 7 to 10 illustrate the top surface structure of the color conversion film according to an example. Figs. 7 to 10 show an example in which the second color conversion layer is provided on one edge side of one side of the first color conversion layer, the edge portion on two side edges, the edge portion on three side edges, and the edge portion on four sides Respectively.

According to another embodiment of the present application, a transparent film is provided on at least one surface of the first color conversion layer. The transparent film is directly contacted to the first color conversion layer or attached through the adhesive layer. When the first color conversion layer is formed by coating a composition for forming a color conversion layer on one side of a transparent film, a separate adhesive layer may not be provided between the transparent film and the first color conversion layer.

3 and 4 show an example in which a transparent film is provided on one side of the first color conversion layer and a transparent film is provided on the other side of the first color conversion layer through an adhesive layer. 3 and 4 show a structure in which a transparent film attached through a pressure-sensitive adhesive layer and a second color conversion layer are adhered to each other, a transparent film attached through the adhesive layer is formed on the second color conversion layer of the first color conversion layer Or may be provided on the opposite surface of the opposed surface.

FIG. 3 shows an adhesive layer on the surface of the second color conversion layer opposite to the first color conversion layer, and a transparent film on the opposite surface to the surface facing the first color conversion layer. And the second color conversion layer can be attached to the first color conversion layer by the adhesive layer. In Fig. 4, a transparent film is provided on both sides of the second color conversion layer, and the second color conversion layer is attached to the first color conversion layer using an adhesive layer. 4, an adhesive layer and a transparent film are sequentially provided on the surface of the second color conversion layer opposite to the first color conversion layer, but the opposite side of the surface of the second color conversion layer opposite to the first color conversion layer An adhesive layer and a transparent film may be provided on the surface in this order.

The transparent film may function as a support in the production of the color conversion layer and may function as a protective film to prevent curling of the color conversion layer. The type of the transparent film 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 or the protective film. Here, transparent means that the visible light transmittance is 70% or more. For example, a PET film may be used as the transparent film. If necessary, a barrier film may be used as the above-mentioned transparent film. As the barrier film, those known in the art can be used.

The adhesive layer is used for attaching a transparent film to the first or second color conversion layer or for attaching the second color conversion layer and the first conversion layer. The adhesive layer may be formed using a material known in the art unless the purpose of the present invention is solved. For example, the pressure-sensitive adhesive layer can be formed by using an adhesive tape or by coating a pressure-sensitive adhesive composition.

According to one embodiment of the present application, the resin matrix of the first color conversion layer and the resin matrix of the second color conversion layer may be the same kind or different kinds may be used. As the resin matrix, a thermoplastic polymer or a thermosetting polymer may be used. Specifically, examples of the material of the resin matrix include poly (meth) acrylate, polycarbonate (PC), polystyrene (PS), polyarylene (PAR), polyurethane (TPU ), Styrene-acrylonitrile series (SAN), polyvinylidene fluoride series (PVDF), modified polyvinylidene fluoride series (modified-PVDF), styrene-ethylene-butylene- Ethylene-butylene-styrene (hydrogenated SEBS) system or the like can be used. Compared to UV curing resins, thermoplastic or thermosetting polymers do not use the UV energy that comes out of the UV curing process and do not have radicals or cations that can attack the phosphors, thus preventing degradation of optical properties by UV energy or radicals or cations can do.

According to one embodiment of the present application, the same kind of phosphor may be used as the phosphor of the first color conversion layer and the phosphor of the second color conversion layer, or different types may be used. The content of the phosphor may be the same or different in the first color conversion layer and the second color conversion layer. The phosphor is not particularly limited as long as it is a phosphor that emits light having a wavelength different from that of the irradiated light. The emission of light of a wavelength different from that of the irradiated light does not necessarily mean that the wavelength of the emitted light and the wavelength of the emitted light do not overlap at all and means that the total wavelength of the emitted light and the total wavelength of the emitted light do not match , And only a part of the wavelength is different. For example, inorganic phosphors, organic phosphors, quantum dots or mixtures thereof may be used. As inorganic phosphors, organic phosphors and quantum dots, those known in the art can be used.

The phosphors of the first color conversion layer and the second color conversion layer may include only red phosphors or both red phosphors and green phosphors.

According to one embodiment of the present application, the phosphor content ratio of the first color conversion layer and the second color conversion layer is preferably 1: 1.5 to 1: 2.5 by weight.

According to one example, as the phosphor, a phosphor that emits light having a wavelength different from that of the light irradiated when light containing a wavelength of 450 nm can be used. For example, as the fluorescent material, a fluorescent material having an emission peak at 450 nm and a half width of 40 nm or less and emitting light upon irradiation with light having a light intensity distribution monomodal may be used. Here, the emitted light may be green light having a wavelength selected from a wavelength of 500 nm to 560 nm, red light having a wavelength selected from a wavelength of 600 nm to 780 nm, or a mixture thereof. For example, the phosphor may include a phosphor that absorbs blue or green light to emit red light, a 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.

The content of the phosphor may be 0.005 part by weight to 2 parts by weight based on 100 parts by weight of the resin matrix.

According to one embodiment of the present application, the thickness of the first or second color conversion layer may be 1 to 200 micrometers. According to one example, the thickness of the first color conversion layer may be 2 to 50 micrometers, and the thickness of the second color conversion layer may be 1 to 50 micrometers, more preferably 1 to 20 micrometers.

The color conversion film according to the above-described embodiments of the present application can be produced by forming a second color conversion layer on at least a part of the edge portion on at least one side of the first color conversion layer. According to one example, a second color conversion layer is attached to at least a part of the edge portion on at least one side of at least one surface of the first color conversion layer using an adhesive layer, or a method of directly coating the composition for producing a second color conversion layer . As a coating method, a method known in the art such as a screen printing method can be used.

Wherein the color conversion layer comprises: coating a resin solution on which a phosphor is dissolved or dispersed; And drying the coated resin solution on the substrate, or extruding the phosphor together with the resin.

When the phosphor is an organic phosphor, since the organic phosphor is dissolved in the resin solution, the organic phosphor is homogeneously distributed in the solution, so that no separate dispersion step is required.

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 phosphor is dissolved or dispersed is not particularly limited if the phosphor and the resin are dissolved or dispersed in the solution.

According to one example, the organic phosphor is dissolved in a solvent to prepare a first solution, the resin is dissolved in a solvent to prepare a second solution, and the first solution and the second solution are mixed, A solution can be prepared. 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, .

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.

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 layer containing a phosphor having a desired thickness and concentration on a substrate can be obtained on a substrate in a direction in which the substrate proceeds in a coating process, and dried under a condition that 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 phosphor is extruded together with the resin to form a film, an extrusion method known in the art may be used. For example, a phosphor may be used as a polycarbonate (PC), a poly (meth) acryl, a styrene- acrylonitrile ) Can be extruded together to produce a color conversion layer.

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. For example, Figs. 11 to 13 show examples. Referring to FIG. 11, a color conversion film according to the above-described embodiments is provided between the light guide plate and the reflection plate. A second color conversion layer may be provided on a surface of the color conversion film adjacent to the light guide plate or a second color conversion layer may be provided on a surface adjacent to the reflection plate of the color conversion film. According to FIG. 12, a color conversion film according to the above-described embodiments is provided on the side opposite to the side opposite to the reflection plate of the light guide plate. The second color conversion layer may be provided on the surface of the color conversion film adjacent to the light guide plate or the second color conversion layer may be provided on the opposite surface of the color conversion film adjacent to the light guide plate. According to Fig. 13, a color conversion film is provided on the side surface of the light guide plate. The second color conversion layer may be provided on the side of the color conversion film adjacent to the light guide plate or the second color conversion layer may be provided on the opposite side of the side of the color conversion film adjacent to the light guide plate. Although a reflection plate is not shown in FIG. 13, a reflection plate may be provided on the rear surface of the light pipe, if necessary.

When a color conversion film is provided on a side surface of the light guide plate as shown in FIG. 13 and the backlight unit includes a side light source, a color conversion film may be provided on a side of the light guide plate except for a portion where a light source is located.

11 to 13 illustrate a configuration including a light source and a reflector surrounding the light source, but the present invention is not limited to such a structure and may be modified in accordance with a backlight unit structure known in the art. In addition, the light source may be a direct-type as well as a side-chain type, and the reflection plate or the reflection layer may be omitted or replaced with another structure if necessary, and if necessary, additional films such as a light diffusion film, Etc. may be further provided.

11 to 13, scattering patterns may be provided on the upper surface or the lower surface of the light guide plate, if necessary. 15 shows an example in which a scattering pattern is provided on a lower surface of the light guide plate, that is, a surface opposite to the reflection plate, and FIG. 16 shows an example in which scattering patterns are provided on the upper surface of the light guide plate, that is, . The light introduced into the light guide plate has an uneven light distribution due to repetition of optical processes such as reflection, total reflection, refraction, and transmission, and the scattering pattern can be used to guide the uneven light distribution to uniform brightness .

According to another embodiment of the present application, a display device including the above-described backlight unit is applied. The display device is not particularly limited as long as it includes the above-described backlight unit as a component. For example, the display device includes a display module and a backlight unit. 17 to 19 illustrate the structure of a display device. However, the present invention is not limited thereto. Further, additional films such as a light diffusion film, a condensing film, a brightness enhancement film, and the like may be additionally provided between the display module and the backlight unit if necessary. Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

Example One

The second color conversion layer including the red organic phosphor and the SAN resin was laminated on the stretched PET on the basis of Din (phosphor concentration (wt%) x thickness (占 퐉)) = 1.35 as Din. An adhesive layer was formed on the surface of the second color conversion layer and adhered to the edge of the first color conversion layer. The width of the second color conversion layer was 2 mm. This? The width of the first color conversion layer was 1215 mm.

Example 2

The procedure of Example 1 was repeated except that the width of the second color conversion layer was changed to 5 mm.

Example 3

Din = 1.2 as a reference.

Example 4

Din = 1.05 as a reference.

Comparative Example One

The procedure of Example 1 was repeated except that the second color conversion layer was not formed.

The results of measuring the physical properties of the color conversion films prepared in Examples 1 to 4 and Comparative Example 1 are shown in Table 1 below.

How to measure

The color conversion films prepared in Examples 1 to 4 and Comparative Examples were placed in a module in an LCM state and measured using SR-UL2 (luminance meter). SR-UL2 was measured about 15 cm from the edge of the LCM module at 4 mm intervals, and the deviations of the portion 15 cm away from the edge portion were measured. The R / G ratio and the R / B ratio are represented by the intensity ratios at the max intensity wavelengths in the red, green, and glue wavelength bands, respectively.

Each deviation is expressed as [the value of the edge portion minus a value of -15 cm].

delete

As shown in Table 1, in the color conversion film prepared in the examples, the red light emission intensity and the color coordinate were uniformly displayed at the edge portion and the center portion.

Claims

A first color conversion layer including a resin matrix and a phosphor dispersed in the resin matrix and emitting light having a wavelength different from that of the irradiated light when irradiated with light having a wavelength of 450 nm; And
And a phosphor dispersed in the resin matrix and emitting light having a wavelength different from that of the light irradiated when the light having a wavelength of 450 nm is irradiated, at least a part of the edge portion on at least one side of the first color conversion layer And a second color conversion layer including a second color conversion layer,
The second color conversion layer is arranged to have a width of 5% or less of the width of the first color conversion layer in the direction perpendicular to the edge line from the edge line of the first color conversion layer,
And the Din value (phosphor concentration X thickness of the second color conversion layer) is 1.05 to 1.35.

The color conversion film according to claim 1, further comprising a transparent film provided on at least one side of the first color conversion layer.

The color conversion film according to claim 1, further comprising a transparent film provided on at least one side of the second color conversion layer.

The liquid crystal display device according to claim 1, further comprising: an adhesive layer provided on a surface of the second color conversion layer opposite to the first color conversion layer, and an adhesive layer provided on an opposite surface of the second color conversion layer, Wherein the color conversion film further comprises a transparent film.

delete

The color conversion film according to claim 1, wherein the thickness of the second color conversion layer is 1 to 20 micrometers.

The color conversion film according to claim 1, wherein the ratio of the phosphor content of the first color conversion layer to the second color conversion layer is 1: 1.5 to 1: 2.5 by weight.

The method according to claim 1, wherein when a light source including blue light having a maximum wavelength of 445 nm and green light having a maximum wavelength of 535 nm is used and a color conversion film is laminated on the light guide plate and the luminescence spectrum is measured with a luminance meter, Wherein the u ', v' deviation measured at 4 mm intervals on any virtual straight line on the film is 0.01 or less and the R / G ratio or R / B ratio deviation is 0.1 or less.

A backlight unit comprising the color conversion film according to any one of claims 1 to 4 and 6 to 8.

A display device comprising a backlight unit according to claim 9.