Liquid crystal display

Abstract

A liquid crystal display according to one aspect of the present invention comprises: a backlight unit having a blue LED light source and a color conversion sheet; and a liquid crystal panel. When the initial chromaticity of the backlight unit is denoted as x0 and the chromaticity of the backlight unit after turning on the blue LED light source for 2000 hours under the condition that the input power amount is 170 W / m2 per unit area of the liquid crystal display in a temperature environment of 50°C is denoted as x1, the relation between said x0 and said x1 is 0.001≤|x1-x0|≤0.020. The color conversion sheet contains at least a light-emitting material and a binder resin. The chromaticity x2 of the liquid crystal panel after CIE standard light source D65 light passes through the liquid crystal panel is 0.335 or less.

Description

LCD display

[0001] The present invention relates to a liquid crystal display, and more particularly to a liquid crystal display including a backlight unit having a blue LED light source and a color conversion sheet, and a liquid crystal panel.

[0002] There has been active research into applying multi-color technology using color conversion methods to liquid crystal displays, organic EL displays, lighting devices, etc. Color conversion refers to converting light emitted from a light emitter into light with a longer wavelength, such as converting blue light into green or red light.

[0003] By forming this composition having color conversion function (hereinafter referred to as color conversion composition) into a sheet and combining it with, for example, a blue light source, it becomes possible to obtain the three primary colors of blue, green, and red from the blue light source, i.e., to obtain white light. A white light source combining such a blue light source with a sheet having color conversion function (hereinafter referred to as color conversion sheet) is used as a backlight unit, and a full-color display can be produced by combining this backlight unit with a liquid crystal driving part and a color filter. Furthermore, a white light source combining a blue light source with a color conversion sheet can also be used as a white light source for LED lighting, etc.

[0004] The problems facing liquid crystal displays that use a color conversion method include the need to improve color reproducibility and durability. To solve these problems, for example, a color conversion sheet has been proposed that uses a pyrromethene compound as a color conversion material, which has a narrow half-width of each emission spectrum, excellent color purity, and improved durability (see, for example, Patent Document 1).

[0005] International Publication No. 2016 / 190283

[0006] However, even with the technology using a pyrromethene compound with improved durability as described in Patent Document 1, there is still a problem in that the chromaticity of the liquid crystal display changes after prolonged use.

[0007] The present invention aims to suppress chromaticity changes in a liquid crystal display that includes a liquid crystal panel and a backlight unit having a blue LED light source and a color conversion sheet, after long-term use.

[0008] The inventors discovered that the cause of the above-mentioned problems is that the chromaticity of a backlight unit having a blue LED light source and a color conversion sheet changes slightly after long-term use, and thus arrived at the present invention.

[0009] That is, in order to solve the above problems and achieve the object, the present invention has the configuration described in any one of [1] to [8] below.

[0010] The liquid crystal display according to the present invention is [1] a liquid crystal display comprising a backlight unit having a blue LED light source and a color conversion sheet, and a liquid crystal panel, wherein the initial chromaticity of the backlight unit is x0, and the input power per unit area of ​​the liquid crystal display is 170 W / m in a temperature environment of 50°C. 2 where x1 is the chromaticity of the backlight unit after the blue LED light source has been turned on for 2000 hours under the above conditions, the relationship between x0 and x1 satisfies 0.001≦|x1−x0|≦0.020, the color conversion sheet contains at least a light-emitting material and a binder resin, and x2 is the chromaticity of the liquid crystal panel after light of CIE standard illuminant D65 has passed through the liquid crystal panel, and x2 is 0.335 or less.

[0011] The liquid crystal display according to the present invention is characterized in that, in the invention described in [1] above, the relationship between x1 and x0 of the backlight unit is −0.020≦x1−x0≦−0.001.

[0012] The liquid crystal display according to the present invention is [3] the invention described in the above [1] or [2], characterized in that the light-emitting material is an organic light-emitting material.

[0013] The liquid crystal display according to the present invention is characterized in that, in the invention described in any one of the above items [1] to [3], the light-emitting material contains a compound represented by the following general formula (1):

[0014] (In the general formula (1), X is C—R 7 Or N. 1 ~R 9 may be the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen atom, a cyano group, an aldehyde group, a carbonyl group, a carboxy group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group, and a fused ring or an aliphatic ring formed between adjacent substituents.

[0015] The liquid crystal display according to the present invention is [5] the invention described in any one of the above [1] to [4], characterized in that the light-emitting material is at least one of the following light-emitting materials (a) and (b): Light-emitting material (a): an organic light-emitting material that emits light with a peak wavelength observed in the range of 500 nm to less than 580 nm when excited with excitation light having a wavelength of 430 nm to 500 nm; and Light-emitting material (b): an organic light-emitting material that emits light with a peak wavelength observed in the range of 580 nm to 750 nm when excited with at least one of excitation light having a wavelength of 430 nm to 500 nm and the emission from the light-emitting material (a).

[0016] Furthermore, the liquid crystal display according to the present invention is, [6] the invention described in any one of the above [1] to [5], characterized in that the content of the luminescent material contained per unit area of ​​the color conversion sheet is 0.12 g / m 2 The present invention is characterized in that:

[0017] Furthermore, the liquid crystal display according to the present invention is characterized in that, in the invention described in any one of the above items [1] to [6], the x2 after the light of the CIE standard illuminant D65 has passed through is 0.230 or more and 0.335 or less.

[0018] Furthermore, the liquid crystal display according to the present invention is characterized in that, in the invention described in any one of the above items [1] to [7], the x2 after the light of the CIE standard illuminant D65 has passed through is 0.250 or more and 0.335 or less.

[0019] According to the present invention, even if the chromaticity of the backlight unit changes due to long-term use, the chromaticity change of the liquid crystal display can be suppressed.

[0020] FIG. 1 is a perspective view showing a schematic external view of a configuration example of a liquid crystal display device including a liquid crystal display according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a configuration example of a liquid crystal display according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a configuration example of a liquid crystal panel according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a configuration example of a backlight unit according to an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing a first example of a color conversion sheet according to an embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing a second example of a color conversion sheet according to an embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing a third example of a color conversion sheet according to an embodiment of the present invention. FIG. 8 is a schematic cross-sectional view showing a fourth example of a color conversion sheet according to an embodiment of the present invention. FIG. 9 is a diagram showing the relative spectral spectrum of the standard illuminant D65 (standardized artificial light source) defined by the International Commission on Illumination (CIE). FIG. 10 is a diagram showing color-matching functions in the XYZ color system defined by the International Commission on Illumination (CIE). FIG. 11 is a diagram showing the emission spectral spectrum of the backlight unit used in Example 1. FIG. 12 is a diagram showing the spectral transmittance of the liquid crystal panel used in Example 1. Fig. 13 is a diagram showing the spectral transmittance of the liquid crystal panels used in Examples 2 and 3. Fig. 14 is a diagram showing the emission spectrum of the backlight unit used in Example 3. Fig. 15 is a diagram showing the spectral transmittance of the liquid crystal panel used in Example 4. Fig. 16 is a diagram showing the spectral transmittance of the liquid crystal panel used in Example 5. Fig. 17 is a diagram showing the spectral transmittance of the liquid crystal panel used in Comparative Example 1.

[0021] Preferred embodiments of the liquid crystal display according to the present invention will be specifically described below, but the present invention is not limited to the following embodiments and can be modified in various ways depending on the purpose and application.

[0022] <Liquid Crystal Display> A liquid crystal display according to an embodiment of the present invention (hereinafter sometimes abbreviated as the liquid crystal display of the present invention) includes a backlight unit having a blue LED light source and a color conversion sheet, and a liquid crystal panel.

[0023] FIG. 1 is an external perspective view showing an example of the configuration of a liquid crystal display device including a liquid crystal display according to an embodiment of the present invention. As shown in FIG. 1, this liquid crystal display device 40 includes a main body 41 having a display screen 43 and a stand 42. The main body 41 of the liquid crystal display device 40 incorporates a liquid crystal display of the present invention (for example, the liquid crystal display 4 shown in FIG. 2 described below) and is supported by the stand 42 as shown in FIG. 1. The display screen 43 is provided in the center of the main body 41 as shown in FIG. 1. The display screen 43 is constituted by a liquid crystal display incorporated in the main body 41. Although not specifically shown, the main body 41 of the liquid crystal display device 40 is also provided with devices such as a liquid crystal driver for driving the liquid crystal display in addition to the liquid crystal display of the present invention.

[0024] Fig. 2 is a schematic cross-sectional view showing an example of the configuration of a liquid crystal display according to an embodiment of the present invention. For example, Fig. 2 shows a schematic cross-sectional view of a liquid crystal display 4, with the viewer side of the display screen 43 of the liquid crystal display device 40 shown in Fig. 1 facing the upper side of the page in Fig. 2 and the opposite side (back side) of the viewer side facing the lower side of the page in Fig. 2. As shown in Fig. 2, the liquid crystal display 4 includes a backlight unit 2 and a liquid crystal panel 3, and is configured by stacking the backlight unit 2 and the liquid crystal panel 3.

[0025] 2 , the backlight unit 2 includes a blue LED light source 21, a reflector 22, a light guide plate 23, a diffusion sheet 24, a color conversion sheet 25, a prism sheet 26, and a reflective polarizing sheet 27. The liquid crystal panel 3 includes a first glass layer 31, a first polarizing film 32, a first alignment film 33, a liquid crystal layer 34, a second alignment film 35, a color filter 36, a second polarizing film 37, and a second glass layer 38.

[0026] (Liquid Crystal Panel) Fig. 3 is a schematic cross-sectional view showing an example of the configuration of a liquid crystal panel according to an embodiment of the present invention. The liquid crystal panel 3 shown in Fig. 3 is of the so-called TN type. Hereinafter, the liquid crystal panel according to an embodiment of the present invention, i.e., the liquid crystal panel provided in the liquid crystal display of the present invention, may be abbreviated as the liquid crystal panel of the present invention.

[0027] In the liquid crystal panel 3, the liquid crystal layer 34 is a layer containing a plurality of liquid crystal molecules, and as shown in Fig. 3, is sandwiched between a first alignment film 33 and a second alignment film 35. The liquid crystal molecules in the liquid crystal layer 34 are aligned by the first alignment film 33 and the second alignment film 35 so as to be twisted at, for example, 90 degrees. Although not shown, transparent electrodes capable of applying a voltage to the liquid crystal layer 34 are connected to the first alignment film 33 and the second alignment film 35. The transparent electrodes are connected to a control unit (not shown) of the liquid crystal display 4 so that the voltage can be controlled for each subpixel.

[0028] As shown in FIG. 3 , a color filter 36 is provided on the outer side of the first alignment film 35 (the side opposite the liquid crystal layer 34). The color filter 36 is partitioned into minute regions corresponding to the sub-pixels. A colorant is applied to each partitioned region on the color filter 36 so that only red, green, or blue light can pass through. Three types of regions, namely, red regions, green regions, and blue regions, are regularly arranged on the color filter 36. Each of these three types of regions is separated by a black matrix that does not transmit light. Three adjacent regions (three colors) colored in different colors on the color filter 36 constitute one pixel in the liquid crystal panel 3.

[0029] As shown in FIG. 3 , a first polarizing film 32 is laminated on the outer side of the second alignment film 33 (the side opposite the liquid crystal layer 34), and a second polarizing film 37 is laminated on the outer side of the color filter 36 (the side opposite the second alignment film 35). Each of the first polarizing film 32 and the second polarizing film 37 is called a polarizer, and absorbs light polarized in one direction that passes through it and transmits linearly polarized light aligned in another direction different from the one direction. The first polarizing film 32 and the second polarizing film 37 are arranged so that their polarization directions intersect perpendicularly. For example, the polarization direction of the first polarizing film 32 is the vertical direction of the display screen 43 (see FIG. 1 ) of the liquid crystal display 4. The polarization direction of the second polarizing film 37 is the horizontal direction of the display screen 43.

[0030] Furthermore, as shown in Fig. 3 , a first glass layer 31 and a second glass layer 38 capable of transmitting light are provided on the outer side of the laminate of the first polarizing film 32, the first alignment film 33, the liquid crystal layer 34, the second alignment film 35, the color filter 36, and the second polarizing film 37. As shown in Fig. 3 , the first glass layer 31 is provided on the outer side of the first polarizing film 32 (the side opposite to the first alignment film 33) and protects the layers of the laminate from the outside of the first polarizing film 32 and is capable of transmitting light. As shown in Fig. 3 , the second glass layer 38 is provided on the outer side of the second polarizing film 37 (the side opposite to the color filter 36) and protects the layers of the laminate from the outside of the second polarizing film 32 and is capable of transmitting light.

[0031] The liquid crystal panel (e.g., liquid crystal panel 3 shown in FIG. 3) included in the liquid crystal display of the present invention is characterized by the following configuration. Specifically, when the chromaticity of the liquid crystal panel after CIE standard illuminant D65 light passes through the liquid crystal panel is defined as x2 (hereinafter, sometimes referred to as chromaticity x2), the chromaticity x2 of the liquid crystal panel of the present invention is 0.335 or less. CIE standard illuminant D65 is a standard illuminant (standardized artificial light source) defined by the International Commission on Illumination (CIE). In a typical liquid crystal panel included in a conventional liquid crystal display, the chromaticity x2 after CIE standard illuminant D65 light passes through is greater than 0.335. In contrast, the liquid crystal panel of the present invention can achieve the chromaticity x2 of 0.335 or less by lowering the transmittance of light in the red region (red light) partitioned on the color filter of the liquid crystal panel relative to light in the green region (green light) and light in the blue region (blue light). For example, by adjusting the film thickness, pigment concentration, and aperture ratio of the red sub-pixel of the color filter, it is possible to adjust the transmittance of light in the red region in the liquid crystal panel of the present invention.

[0032] When the chromaticity x2 of a liquid crystal panel after transmission of CIE standard illuminant D65 light is 0.335 or less, by combining the liquid crystal panel with a backlight unit having the characteristic described below that the chromaticity x changes to a certain extent over long periods of illumination, the amount of change in the chromaticity x of the liquid crystal display can be suppressed. This is thought to be because, by relatively lowering the transmittance of light in the red region of the liquid crystal panel as described above, the influence of changes in the chromaticity x of the backlight unit (particularly changes in the intensity of light in the red region) on the chromaticity of the liquid crystal display can be reduced. There is no particular lower limit for the chromaticity x2 of the liquid crystal panel, but from the viewpoint of the color gamut and brightness of the liquid crystal display, it is preferably 0.230 or more, and more preferably 0.250 or more.

[0033] The chromaticity x of the liquid crystal panel after light of CIE standard illuminant D65 has passed through it can be calculated from the color matching function in the XYZ color system, the relative spectrum of CIE standard illuminant D65, and the spectral transmittance of the liquid crystal panel, as will be described in the Examples section below.

[0034] (Backlight Unit) The backlight unit provided in the liquid crystal display of the present invention (hereinafter sometimes abbreviated as the backlight unit of the present invention) has at least a blue LED light source and a color conversion sheet. The arrangement of the blue LED light source and the color conversion sheet in the backlight unit is not particularly limited, and the blue LED light source and the color conversion sheet may be closely attached to each other, or a remote phosphor type in which the blue LED light source and the color conversion sheet are separated from each other may be used. The backlight unit of the present invention may also be configured to include an optical sheet such as a prism sheet or a diffusion sheet.

[0035] The backlight unit of the liquid crystal display of the present invention is characterized by having the following configuration: That is, assuming that the initial chromaticity of the backlight unit is x0, 、 In a temperature environment of 50°C, the input power per unit area of ​​the LCD is 170 W / m 2When the chromaticity of the backlight unit after the blue LED light source of the backlight unit is turned on for 2000 hours under the above conditions is denoted by x1, the relationship between x0 and x1 satisfies the following mathematical formula (A1): 0.001≦|x1−x0|≦0.020 (A1)

[0036] In the present invention, the area of ​​a liquid crystal display is the area of ​​a backlight unit included in the liquid crystal display. For example, the area of ​​the backlight unit is the area of ​​a color conversion sheet included in the backlight unit (e.g., color conversion sheet 25 shown in FIG. 2 ). The area of ​​the color conversion sheet is preferably the same as the area of ​​the light exit surface of the backlight unit. Note that the light exit surface of the backlight unit is, for example, the surface from which the backlight unit 2 shown in FIG. 2 emits light to the liquid crystal panel 3, and in FIG. 2, it is the light exit surface of the reflective deflection sheet 27 (the surface facing the first glass layer 31 of the liquid crystal panel 3). Furthermore, the area of ​​the backlight unit as the area of ​​a liquid crystal display is preferably the same as the area of ​​the light exit surface of the liquid crystal panel included in the liquid crystal display. The light exit surface of the liquid crystal panel is, for example, the light exit surface of the second glass layer 38 of the liquid crystal panel 3 shown in FIG. 2 , which corresponds to the display screen of the liquid crystal display of the present invention (display screen 43 shown in FIG. 1 ).

[0037] Furthermore, the relationship between x1 and x0 preferably satisfies the following formula (A2): −0.020≦x1−x0≦−0.001 (A2).

[0038] Equation (A1) shows that the chromaticity x of a backlight unit changes when the backlight unit is operated alone for a long period of time. Equation (A2) shows that the chromaticity x of the backlight unit changes in the negative direction after the backlight unit has been operated for a long period of time. Hereinafter, the x0 may be referred to as the chromaticity x0 or the initial chromaticity x0. The x1 may be referred to as the chromaticity x1 or the aged chromaticity x1.

[0039] The change in chromaticity x of the backlight unit as shown by Equation (A1) or Equation (A2) is believed to be due to degradation of the light-emitting material in the color conversion sheet of the backlight unit caused by prolonged illumination of the blue LED light source of the backlight unit. This degradation of the light-emitting material is caused by singlet oxygen. Singlet oxygen is an oxygen molecule in a singlet state in which the two electrons occupying the π* orbital (antibonding π orbital) of the oxygen molecule's molecular orbital have different spin directions, i.e., an excited state in which the total spin quantum number is 0. This excited state exists in two states: the Σ1 state, in which each of the two π* orbitals is occupied by an electron with a different spin direction, and the Δ1 state, in which only one of the π* orbitals is occupied by two electrons with a different spin direction. In the Δ1 state, the vacant electron orbital of singlet oxygen has strong electrophilicity and strong oxidizing power. Therefore, singlet oxygen is believed to cause degradation of the light-emitting material through oxidation.

[0040] In such cases where changes in the chromaticity x of the backlight unit inevitably occur, by combining a liquid crystal panel having the characteristics described above with the backlight unit, the liquid crystal display of the present invention has the effect of suppressing changes in the chromaticity x.

[0041] Fig. 4 is a schematic cross-sectional view showing an example of the configuration of a backlight unit according to an embodiment of the present invention. For example, the backlight unit 2 shown in Fig. 4 includes a blue LED light source 21, a reflector 22, a light guide plate 23, a diffusion sheet 24, a color conversion sheet 25, a prism sheet 26, and a reflective deflection sheet 27. Specifically, in the backlight unit 2, as shown in Fig. 4, the blue LED light source 21 is disposed so as to abut against a side surface of the light guide plate 23. Although not shown, a plurality of LED elements emitting blue light are disposed inside the blue LED light source 21. The blue LED light source 21 irradiates light (blue light) toward the side surface of the light guide plate 23.

[0042] The type of blue LED light source 21 is not particularly limited as long as it emits light in a wavelength range that can be absorbed by the luminescent material contained in the color conversion sheet 25. The blue LED light source 21 may have one emission peak or two or more emission peaks. In particular, to improve color purity, a blue LED light source 21 having one emission peak is preferable. Furthermore, instead of a single blue LED light source 21, it is also possible to use any combination of multiple blue LED light sources with different emission peaks. From the viewpoint of improving the color purity of blue light, a blue LED light source having a light source with a wavelength in the range of 430 nm to 500 nm is particularly preferable in the backlight unit of the present invention.

[0043] In the backlight unit 2 shown in Fig. 4, light (blue light) emitted from the blue LED light source 21 is incident on the light guide plate 23. As shown in Fig. 4, a reflector 22 for reflecting light is laminated on the lower surface of the light guide plate 23. As shown in Fig. 4, a diffusion sheet 24, a color conversion sheet 25, a prism sheet 26, and a reflective polarizing sheet 27 are laminated in this order on the upper surface of the light guide plate 23 (the surface opposite to the reflector 22).

[0044] While an edge-type backlight unit is illustrated in Fig. 4, the present invention is not limited thereto, and a direct-type backlight may also be used as the backlight unit of the present invention. An edge-type backlight unit, like the backlight unit 2 illustrated in Fig. 4, is configured to uniformly diffuse light by illuminating light from a light source (blue LED light source 21 in Fig. 4) through one edge surface of a light guide plate (one side surface of light guide plate 23 in Fig. 4). On the other hand, a direct-type backlight unit is configured to irradiate light from the light source from below the liquid crystal panel via a diffusion panel or the like.

[0045] (Color Conversion Sheet) The color conversion sheet provided in the backlight unit of the present invention (e.g., color conversion sheet 25 shown in FIG. 4) converts incident light from a light emitter such as a light source into light of a different wavelength from the incident light (i.e., color conversion), and contains at least a binder resin and a luminescent material. The luminescent material contained in the color conversion sheet converts blue light from a blue LED light source provided in the backlight unit of the present invention into light of a different wavelength from the blue light. Here, "converting into light of a different wavelength from the incident light" preferably converts into light of a longer wavelength than the incident light. Hereinafter, the color conversion sheet provided in the backlight unit of the present invention may be abbreviated as the color conversion sheet of the present invention.

[0046] The color conversion sheet of the present invention includes a color conversion layer that is a layer made of the color conversion composition described below or a cured product thereof. The cured product of the color conversion composition is preferably included in the color conversion sheet as a layer obtained by curing the color conversion composition (a layer made of the cured product of the color conversion composition). Representative structural examples of the color conversion sheet of the present invention include the following four, for example.

[0047] 5 is a schematic cross-sectional view showing a first example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 5, this first example of a color conversion sheet 1A is a laminate of a base layer 10 and a color conversion layer 11. In this structural example of the color conversion sheet 1A, the color conversion layer 11 is laminated on the base layer 10.

[0048] 6 is a schematic cross-sectional view showing a second example of a color conversion sheet according to an embodiment of the present invention. As shown in Fig. 6, this second example of a color conversion sheet 1B is a laminate of multiple base material layers 10 and a color conversion layer 11. In this structural example of color conversion sheet 1B, the color conversion layer 11 is sandwiched between multiple base material layers 10.

[0049] 7 is a schematic cross-sectional view showing a third example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 7, this third example color conversion sheet 1C is a laminate of multiple base layers 10, a color conversion layer 11, and multiple barrier films 12. In this structural example of color conversion sheet 1C, the color conversion layer 11 is sandwiched between multiple barrier films 12, and the laminate of the color conversion layer 11 and the multiple barrier films 12 is further sandwiched between multiple base layers 10. In other words, color conversion sheet 1C may have a barrier film 12 as shown in FIG. 7 to prevent deterioration of the color conversion layer 11 due to oxygen, moisture, or heat.

[0050] 8 is a schematic cross-sectional view showing a fourth example of a color conversion sheet according to an embodiment of the present invention. As shown in Fig. 8, the fourth example of a color conversion sheet 1D is a laminate of multiple base layers 10 and multiple color conversion layers 11. In this structural example of the color conversion sheet 1D, the laminate of multiple color conversion layers 11 is sandwiched between multiple base layers 10.

[0051] The film thickness of the color conversion sheet of the present invention is not particularly limited, but is preferably 30 μm or more and 5000 μm or less, more preferably 30 μm or more and 1000 μm or less, and particularly preferably 30 μm or more and 300 μm or less. Here, the film thickness of the color conversion sheet refers to the combined film thickness of all layers contained in the color conversion sheet, and the film thickness of the color conversion sheet of the present invention refers to the film thickness (average film thickness) measured based on Method A, a mechanical scanning thickness measurement method, in JIS K7130 (1999) Plastics - Films and Sheets - Thickness Measurement Method. By making the film thickness of the color conversion sheet of the present invention 30 μm or more, the toughness of the color conversion sheet can be improved. By making the film thickness of the color conversion sheet of the present invention 5000 μm or less, cracking of the color conversion sheet can be suppressed.

[0052] The content of the light-emitting material contained per unit area of ​​the color conversion sheet of the present invention is 0.12 g / m from the viewpoint of suppressing the white point on the chromaticity coordinates of the liquid crystal display from becoming bluish. 2 It is preferable that the content is 0.15 g / m or more. 2The upper limit of the content of the light-emitting material is not particularly limited, but is preferably 1.50 g / m or more. 2 It is preferable that:

[0053] (Color conversion layer) In the present invention, the color conversion layer (for example, color conversion layer 11 shown in Figures 5 to 8) contains a light-emitting material and a binder resin. For example, the color conversion layer can be formed by applying a color conversion composition prepared by the method described below to an underlayer such as a substrate layer or a barrier film, and then drying the applied composition. Hereinafter, the color conversion layer of the color conversion sheet of the present invention may be abbreviated as the color conversion layer of the present invention.

[0054] The thickness of the color conversion layer of the present invention is not particularly limited, but is preferably 10 μm or more and 1000 μm or less. The lower limit of the thickness of the color conversion layer is more preferably 30 μm or more. The upper limit of the thickness of the color conversion layer is more preferably 200 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less. The thickness of the color conversion layer of the present invention is measured by the same method as that for the thickness of the color conversion sheet described above.

[0055] In the color conversion sheet of the present invention, the color conversion layer may be one layer or two or more layers. In addition to the above-mentioned luminescent material and binder resin, the color conversion layer may contain other components (additives) such as a light stabilizer, an antioxidant, a processing and heat stabilizer, a light resistance stabilizer such as an ultraviolet absorber, scattering particles, silicone fine particles, and a silane coupling agent, or may contain a small amount of solvent (residual solvent), or may contain both these additives and a solvent.

[0056] From the viewpoint of further improving the durability of a color conversion sheet having the color conversion layer, the amount of residual solvent in the color conversion layer of the present invention is preferably 3.0 wt % or less, more preferably 1.0 wt % or less, and particularly preferably 0.5 wt % or less. Furthermore, from the viewpoint of improving the quantum yield of the color conversion sheet, the amount of residual solvent is preferably 0.01 wt % or more, more preferably 0.05 wt % or more, and particularly preferably 0.09 wt % or more.

[0057] (Color Conversion Composition) The color conversion composition according to an embodiment of the present invention (hereinafter sometimes abbreviated as the color conversion composition of the present invention) constitutes the color conversion layer of the color conversion sheet of the present invention. The color conversion composition contains at least a light-emitting material and a binder resin. An example of a method for producing the color conversion composition of the present invention is described below. In this production method, the light-emitting material, binder resin, and, if necessary, additives and solvents are mixed to a predetermined composition, and then the mixture is homogeneously mixed or kneaded using a stirrer / kneader to obtain the color conversion composition. Examples of the stirrer / kneader include a homogenizer, a planetary stirrer, a three-roller mixer, a ball mill, a planetary ball mill, and a bead mill. After mixing or dispersing, or during the mixing or dispersing process, degassing under vacuum or reduced pressure conditions is also preferably performed. It is also possible to premix certain components or to perform aging or other treatments. The desired solids concentration can also be achieved by removing the solvent using an evaporator.

[0058] (Light-emitting material) The color-converting composition of the present invention contains at least one light-emitting material. Here, the light-emitting material in the present invention refers to a material that, when irradiated with some light, emits light of a wavelength different from the light. It is preferable that the light-emitting material converts light irradiated from a light-emitting body such as a light source into light of a longer wavelength than the light (color conversion).

[0059] Examples of luminescent materials include inorganic phosphors, fluorescent pigments, fluorescent dyes, and quantum dots. The color conversion composition of the present invention may contain two or more of these luminescent materials. To achieve highly efficient color conversion, the luminescent material contained in the color conversion composition of the present invention is preferably a luminescent material exhibiting luminescent characteristics with a high quantum yield. For example, quantum dots and organic luminescent materials are preferred as the luminescent material, and among these, organic luminescent materials are more preferred. When a color conversion sheet contains a luminescent material that emits green light and a luminescent material that emits red light, and organic luminescent materials are used as both luminescent materials, in a backlight unit including the color conversion sheet, the change in chromaticity of the backlight unit after long-term use is greater in chromaticity x than in chromaticity y. Therefore, the effect of suppressing change in chromaticity x of the liquid crystal display by combining the liquid crystal panel of the present invention, which has a relatively low transmittance of light in the red region (wavelengths of 580 nm to 750 nm) compared to conventional light sources, with the backlight unit of the present invention is particularly significant when an organic luminescent material is used as the luminescent material. Details of "green emission" and "red emission" in the present invention will be described later. Furthermore, the chromaticity x and chromaticity y are each expressed by chromaticity coordinates in the XYZ color system.

[0060] Examples of suitable organic light-emitting materials include compounds having a fused aryl ring, such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, and indene, and derivatives thereof. Examples of suitable organic light-emitting materials include compounds having a heteroaryl ring, such as furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9'-spirobisilafluorene, benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyridine, pyrazine, naphthyridine, quinoxaline, and pyrrolopyridine, and derivatives thereof, and borane derivatives.

[0061] Other suitable organic light-emitting materials include stilbene derivatives such as 1,4-distyrylbenzene, 4,4'-bis(2-(4-diphenylaminophenyl)ethenyl)biphenyl, and 4,4'-bis(N-(stilben-4-yl)-N-phenylamino)stilbene; aromatic acetylene derivatives; tetraphenylbutadiene derivatives; aldazine derivatives; pyrromethene derivatives; and diketopyrrolo[3,4-c]pyrrole derivatives. Other suitable organic light-emitting materials include coumarin derivatives such as coumarin 6, coumarin 7, and coumarin 153; azole derivatives and metal complexes thereof such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, and triazole; cyanine compounds such as indocyanine green; and xanthene and thioxanthene compounds such as fluorescein, eosin, and rhodamine.

[0062] Suitable organic light-emitting materials include polyphenylene compounds, naphthalimide derivatives, phthalocyanine derivatives and their metal complexes, porphyrin derivatives and their metal complexes, oxazine compounds such as Nile Red and Nile Blue, helicene compounds, and aromatic amine derivatives such as N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine. Suitable organic light-emitting materials also include organometallic complex compounds of iridium (Ir), ruthenium (Ru), rhodium (Rh), palladium (Pd), platinum (Pt), osmium (Os), and rhenium (Re). However, the organic light-emitting materials of the present invention are not limited to those described above.

[0063] The organic light-emitting material may be a fluorescent material or a phosphorescent material, but fluorescent materials are preferred in order to achieve high color purity. Among them, pyrromethene derivatives are preferably used as the organic light-emitting material because they provide a high fluorescence quantum yield and have better chromaticity durability. A more preferred organic light-emitting material is a compound represented by the following general formula (1):

[0064]

[0065] In the general formula (1), X is C—R7 Or N. 1 ~R 9 may be the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen atom, a cyano group, an aldehyde group, a carbonyl group, a carboxy group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group, and a fused ring or an aliphatic ring formed between adjacent substituents.

[0066] In all of the above groups, hydrogen may be deuterium. This also applies to the compounds or partial structures thereof described below. In the following description, for example, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms refers to an aryl group having a total carbon number of 6 to 40, including the carbon atoms contained in the substituents substituted on the aryl group. The same applies to other substituents that specify the number of carbon atoms.

[0067] In addition, in all of the above groups, the substituent when substituted is preferably an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen, a cyano group, an aldehyde group, a carbonyl group, a carboxy group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, or a phosphine oxide group, and more preferably a specific substituent that is preferred in the description of each substituent.In addition, these substituents may be further substituted with the above-mentioned substituent.

[0068] The term "unsubstituted" in the context of "substituted or unsubstituted" means that a hydrogen atom or a deuterium atom has been substituted. The same applies to the term "substituted or unsubstituted" in the compounds or partial structures thereof described below.

[0069] Of all the groups mentioned above, the alkyl group refers to a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group, which may or may not have a substituent. When substituted, the additional substituent is not particularly limited, and examples thereof include an alkyl group, a halogen, an aryl group, and a heteroaryl group, and this point is also common to the following description. Furthermore, the number of carbon atoms in the alkyl group is not particularly limited, but is preferably in the range of 1 to 20, more preferably 1 to 8, from the viewpoints of ease of availability and cost.

[0070] The cycloalkyl group refers to a saturated alicyclic hydrocarbon group, such as a cyclopropyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, or the like, which may or may not have a substituent. The number of carbon atoms in the alkyl group is not particularly limited, but is preferably in the range of 3 to 20.

[0071] The heterocyclic group refers to an aliphatic ring having atoms other than carbon atoms in the ring, such as a pyran ring, a piperidine ring, or a cyclic amide, which may or may not have a substituent. The number of carbon atoms in the heterocyclic group is not particularly limited, but is preferably in the range of 2 to 20.

[0072] The alkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond, such as a vinyl group, an allyl group, or a butadienyl group, which may or may not have a substituent. The number of carbon atoms in the alkenyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0073] The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond, such as a cyclopentenyl group, a cyclopentadienyl group, or a cyclohexenyl group, which may or may not have a substituent. The number of carbon atoms in the cycloalkenyl group is not particularly limited, but is preferably in the range of 3 to 20.

[0074] The alkynyl group refers to an unsaturated aliphatic hydrocarbon group containing a triple bond, such as an ethynyl group, which may or may not have a substituent. The number of carbon atoms in the alkynyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0075] The alkoxy group refers to a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond, such as a methoxy group, an ethoxy group, or a propoxy group, and this aliphatic hydrocarbon group may or may not have a substituent. The number of carbon atoms in the alkoxy group is not particularly limited, but is preferably in the range of 1 to 20.

[0076] An alkylthio group is an alkoxy group in which the oxygen atom of the ether bond is replaced with a sulfur atom. The hydrocarbon group of the alkylthio group may or may not have a substituent. The number of carbon atoms in the alkylthio group is not particularly limited, but is preferably in the range of 1 to 20.

[0077] The aryl ether group refers to a functional group in which an aromatic hydrocarbon group is bonded via an ether bond, such as a phenoxy group, and the aromatic hydrocarbon group may or may not have a substituent. The number of carbon atoms in the aryl ether group is not particularly limited, but is preferably in the range of 6 to 40.

[0078] An aryl thioether group is an aryl ether group in which the oxygen atom of the ether bond is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl thioether group may or may not have a substituent. The number of carbon atoms in the aryl thioether group is not particularly limited, but is preferably in the range of 6 to 40.

[0079] The aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthryl group, an anthracenyl group, a benzophenanthryl group, a benzanthracenyl group, a chrysenyl group, a pyrenyl group, a fluoranthenyl group, a triphenylenyl group, a benzofluoranthenyl group, a dibenzoanthracenyl group, a perylenyl group, or a helicenyl group. Among these, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, an anthracenyl group, a pyrenyl group, a fluoranthenyl group, or a triphenylenyl group is preferred. The aryl group may or may not have a substituent. The number of carbon atoms in the aryl group is not particularly limited, but is preferably in the range of 6 to 40, more preferably 6 to 30.

[0080] R 1 ~R 9 When is a substituted or unsubstituted aryl group, the aryl group is preferably a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, or an anthracenyl group, more preferably a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, even more preferably a phenyl group, a biphenyl group, or a terphenyl group, and particularly preferably a phenyl group.

[0081] When each of the substituents is further substituted with an aryl group, the aryl group is preferably a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, or an anthracenyl group, more preferably a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, and particularly preferably a phenyl group.

[0082] Examples of heteroaryl groups include pyridyl, furanyl, thienyl, quinolinyl, isoquinolinyl, pyrazinyl, pyrimidyl, pyridazinyl, triazinyl, naphthyridinyl, cinnolinyl, phthalazinyl, quinoxalinyl, quinazolinyl, benzofuranyl, benzothienyl, indolyl, dibenzofuranyl, dibenzothienyl, carbazolyl, and benzocarbazolyl. It refers to a cyclic aromatic group having one or more atoms other than carbon in the ring, such as a benzoyl group, a carbolinyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, a dihydroindenocarbazolyl group, a benzoquinolinyl group, an acridinyl group, a dibenzoacridinyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group. However, a naphthyridinyl group refers to a 1,5-naphthyridinyl group, a 1,6-naphthyridinyl group, a 1,7-naphthyridinyl group, a 1,8-naphthyridinyl group, a 2,6-naphthyridinyl group, or a 2,7-naphthyridinyl group. The heteroaryl group may or may not have a substituent. The number of carbon atoms in the heteroaryl group is not particularly limited, but is preferably in the range of 2 or more and 40 or less, and more preferably 2 or more and 30 or less.

[0083] R 1 ~R 9 is a substituted or unsubstituted heteroaryl group, the heteroaryl group is preferably a pyridyl group, a furanyl group, a thienyl group, a quinolinyl group, a pyrimidyl group, a triazinyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a dibenzofuranyl group, a dibenzothienyl group, a carbazolyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group, more preferably a pyridyl group, a furanyl group, a thienyl group, or a quinolinyl group, and particularly preferably a pyridyl group.

[0084] When each substituent is further substituted with a heteroaryl group, the heteroaryl group is preferably a pyridyl group, a furanyl group, a thienyl group, a quinolinyl group, a pyrimidyl group, a triazinyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a dibenzofuranyl group, a dibenzothienyl group, a carbazolyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group, more preferably a pyridyl group, a furanyl group, a thienyl group, or a quinolinyl group, and particularly preferably a pyridyl group.

[0085] The term "halogen" refers to an atom selected from fluorine, chlorine, bromine, and iodine. The carbonyl group, carboxy group, oxycarbonyl group, and carbamoyl group may or may not have a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group, and these substituents may be further substituted.

[0086] The amino group is a substituted or unsubstituted amino group. The amino group may or may not have a substituent. When substituted, examples of the substituent include an aryl group, a heteroaryl group, a linear alkyl group, a branched alkyl group, and the like. Preferred aryl groups and heteroaryl groups are a phenyl group, a naphthyl group, a pyridyl group, and a quinolinyl group. These substituents may be further substituted. The number of carbon atoms is not particularly limited, but is preferably in the range of 2 to 50, more preferably 6 to 40, and particularly preferably 6 to 30.

[0087] The silyl group refers to, for example, alkylsilyl groups such as trimethylsilyl group, triethylsilyl group, tert-butyldimethylsilyl group, propyldimethylsilyl group, and vinyldimethylsilyl group, and arylsilyl groups such as phenyldimethylsilyl group, tert-butyldiphenylsilyl group, triphenylsilyl group, and trinaphthylsilyl group. The substituent on silicon may be further substituted. The number of carbon atoms in the silyl group is not particularly limited, but is preferably in the range of 1 to 30.

[0088] The siloxanyl group refers to a silicon compound group via an ether bond, such as a trimethylsiloxanyl group. The substituent on the silicon may be further substituted. The boryl group refers to a substituted or unsubstituted boryl group. The boryl group may or may not have a substituent, and in the case of substitution, examples of the substituent include an aryl group, a heteroaryl group, a linear alkyl group, a branched alkyl group, an aryl ether group, an alkoxy group, and a hydroxyl group. Among these, an aryl group and an aryl ether group are preferred. The phosphine oxide group refers to a group represented by the formula -P(=O)R 10 R 11 R is a group represented by the formula: 10 R 11 is R 1 ~R 9 is selected from the same group as

[0089] The fused ring or aliphatic ring formed between adjacent substituents refers to any two adjacent substituents (for example, R 1 and R 2 ) are bonded to each other to form a conjugated or non-conjugated cyclic skeleton. The constituent elements of such a fused ring or aliphatic ring may include, in addition to carbon, an element selected from nitrogen, oxygen, sulfur, phosphorus, and silicon. Furthermore, the above-mentioned fused ring or aliphatic ring may be further fused with another ring.

[0090] The compound represented by general formula (1) exhibits a high fluorescence quantum yield and a small half-width peak of the emission spectrum, and therefore can achieve both efficient color conversion and high color purity, and can further improve the durability of chromaticity.

[0091] Examples of the compound represented by general formula (1) are shown below, but the compound is not limited to these.

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100] The color-converting composition of the present invention preferably contains the following luminescent material (a). The luminescent material (a) is a luminescent material that, when excited with excitation light having a wavelength in the range of 430 nm to 500 nm, emits light with a peak wavelength observed in the range of 500 nm to less than 580 nm. Hereinafter, the light emitted with a peak wavelength in the range of 500 nm to less than 580 nm will be referred to as "green light" as necessary. Generally, the greater the energy of excitation light, the more likely it is to cause material decomposition. However, excitation light having a wavelength in the range of 430 nm to 500 nm has a relatively small excitation energy. Therefore, green light with good color purity can be obtained without causing decomposition of the luminescent material (a) in the color-converting composition.

[0101] The color-converting composition of the present invention preferably contains the above-mentioned luminescent material (a) and the following luminescent material (b). As described above, the luminescent material (a) is a luminescent material that emits light with a peak wavelength of 500 nm or more and less than 580 nm when excited with excitation light having a wavelength of 430 nm or more and 500 nm or less. The luminescent material (b) is a luminescent material that emits light with a peak wavelength observed in the range of 580 nm or more and 750 nm or less when excited with at least one of excitation light having a wavelength of 430 nm or more and 500 nm or less and the emission from the luminescent material (a). Hereinafter, the emission with a peak wavelength observed in the range of 580 nm or more and 750 nm or less will be referred to as "red emission" as necessary. The luminescent material contained in the color-converting composition of the present invention is preferably at least one of the luminescent materials (a) and (b).

[0102] Because a portion of excitation light in the wavelength range of 430 nm to 500 nm is partially transmitted through the color conversion sheet of the present invention, when a blue LED with a sharp emission peak is used as a light source, the sheet exhibits a sharply shaped emission spectrum in each of the blue, green, and red colors, thereby producing white light with excellent color purity. As a result, particularly in displays, a wider color gamut with more vivid colors can be efficiently produced. Furthermore, in lighting applications, the sheet offers improved emission characteristics, particularly in the green and red regions, compared to white LEDs that combine a blue LED with a yellow phosphor, which is currently the mainstream, and therefore provides a desirable white light source with improved color rendering properties.

[0103] Examples of the light-emitting material (a) include coumarin derivatives such as coumarin 6, coumarin 7, and coumarin 153, cyanine derivatives such as indocyanine green, fluorescein derivatives such as fluorescein, fluorescein isothiocyanate, and carboxyfluorescein diacetate, phthalocyanine derivatives such as phthalocyanine green, perylene derivatives such as diisobutyl-4,10-dicyanoperylene-3,9-dicarboxylate, pyrromethene derivatives, stilbene derivatives, oxazine derivatives, naphthalimide derivatives, pyrazine derivatives, benzimidazole derivatives, benzoxazole derivatives, benzothiazole derivatives, imidazopyridine derivatives, azole derivatives, compounds having a fused aryl ring such as anthracene and derivatives thereof, aromatic amine derivatives, and organometallic complex compounds. The color-changing composition of the present invention may contain two or more of these as the light-emitting material (a).

[0104] Among these compounds, pyrromethene derivatives are particularly preferred because they provide high fluorescence quantum yield and good durability of color purity. Among pyrromethene derivatives, the compound represented by general formula (1) is preferred because it exhibits light emission with high color purity.

[0105] Examples of the light-emitting material (b) include cyanine derivatives such as 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostillyl)-4H-pyran; rhodamine derivatives such as rhodamine B, rhodamine 6G, rhodamine 101, and sulforhodamine 101; pyridine derivatives such as 1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridinium-perchlorate; perylene derivatives such as N,N'-bis(2,6-diisopropylphenyl)-1,6,7,12-tetraphenoxyperylene-3,4:9,10-bisdicarboimide; porphyrin derivatives; pyrromethene derivatives; oxazine derivatives; pyrazine derivatives; compounds having a fused aryl ring such as naphthacene and dibenzodiindenoperylene; and organometallic complex compounds. The color-changing composition of the present invention may contain two or more of these as the light-emitting material (b).

[0106] Among these compounds, pyrromethene derivatives are particularly preferred because they provide high fluorescence quantum yield and good durability of color purity. Among pyrromethene derivatives, the compound represented by general formula (1) is preferred because it exhibits light emission with high color purity.

[0107] Compounds that emit delayed fluorescence can also be suitably used as the organic light-emitting material contained in the color-converting composition of the present invention. Compounds that emit delayed fluorescence are discussed on pages 87-103 of "State-of-the-Art Organic EL" (edited by Adachi Chinaya and Fujimoto Hiroshi, published by CMC Publishing). This document explains that by bringing the energy levels of the excited singlet and triplet states of the light-emitting material closer together, reverse energy transfer from the excited triplet state, which normally has a low transition probability, to the excited singlet state occurs with high efficiency, resulting in the development of thermally activated delayed fluorescence (TADF). Furthermore, Figure 5 in this document explains the mechanism by which delayed fluorescence occurs. Delayed fluorescence emission can be confirmed by transient photoluminescence (PL) measurements.

[0108] Typically, fluorescent light is emitted from a singlet excited state generated after photoexcitation of a light-emitting material. The triplet excited state of the light-emitting material generated by intersystem crossing is thermally deactivated at room temperature. Therefore, fluorescence is not emitted from the triplet excited state of the light-emitting material. On the other hand, as described above, a compound that emits delayed fluorescence is excited to a singlet excited state by photoexcitation, and even if a triplet excited state is generated by intersystem crossing, it is quickly converted to a singlet excited state and then emits fluorescence. Therefore, a compound that emits delayed fluorescence can also contribute to fluorescent light emission from a triplet excited state that cannot contribute to light emission in ordinary fluorescent materials. In other words, since highly efficient light emission can be obtained, a compound that emits delayed fluorescence is preferred as an organic light-emitting material to be contained in the color-converting composition of the present invention. Furthermore, a compound that emits delayed fluorescence quickly converts its triplet excited state to a singlet excited state. Therefore, singlet oxygen is less likely to be generated, and as a result, the durability of a color-converting composition containing the compound can be expected to be improved.

[0109] The content of the luminescent material in the color-converting composition of the present invention can be selected depending on the molar absorption coefficient, fluorescence quantum yield, and absorption intensity at the excitation wavelength of the compound, as well as the film thickness and transmittance of the color-converting sheet to be produced (specifically, the color-converting layer contained in the color-converting sheet). Here, the content of the luminescent material refers to the total content when the color-converting composition of the present invention contains two or more luminescent materials. The content of the luminescent material is 1.0 × 10 relative to 100 parts by weight of the binder resin. -2 It is preferably from 1 part by weight to 5 parts by weight.

[0110] Furthermore, when the color-changing composition of the present invention contains both a light-emitting material (a) that emits green light and a light-emitting material (b) that emits red light, a part of the green light is converted to red light. b That is, w a ≧w b It is preferable that the content ratio w of the light-emitting material (a) and the light-emitting material (b) is a :w bis preferably 200:1 to 3:1. a and content w b is the weight percent relative to the weight of the binder resin in the color converting composition of the present invention.

[0111] In the color conversion sheet of the present invention, the content of the luminescent material per unit area of ​​the color conversion layer containing the luminescent material is 0.12 g / m from the viewpoint of the white point on the chromaticity coordinate when a backlight unit having the color conversion sheet is turned on (i.e., when the liquid crystal display of the present invention is turned on). 2 It is preferable that the content is 0.15 g / m or more. 2 It is more preferable that the content of the light-emitting material per unit area of ​​the color conversion sheet is 0.12 g / m or more. 2 If the content of the light-emitting material per unit area is less than 1.50 g / m, the white point on the chromaticity coordinates of a liquid crystal display having the color conversion sheet in a backlight unit will be tinged with blue. 2 The following is preferred:

[0112] (Binder Resin) The color-converting composition of the present invention contains a binder resin in addition to the above-described light-emitting material. The binder resin forms a continuous phase and may be a material that is excellent in moldability, transparency, heat resistance, and the like. Examples of binder resins include known materials such as photocurable resist materials having reactive vinyl groups, such as acrylic acid-based, methacrylic acid-based, polyvinyl cinnamate-based, and cyclic rubber-based materials, epoxy resins, silicone resins (including organopolysiloxane cured products (crosslinked products) such as silicone rubber and silicone gel), urea resins, fluororesins, polycarbonate resins, acrylic resins, urethane resins, melamine resins, polyvinyl resins, polyamide resins, phenolic resins, polyvinyl alcohol resins, cellulose resins, aliphatic ester resins, aromatic ester resins, aliphatic polyolefin resins, and aromatic polyolefin resins. Furthermore, copolymer resins of these may also be used as the binder resin. By appropriately designing these resins, binder resins useful for the color-converting composition and color-converting sheet of the present invention can be obtained. Among these resins, thermoplastic resins are more preferred because of the ease of sheet formation. Among thermoplastic resins, epoxy resins, silicone resins, acrylic resins, ester resins, olefin resins, or mixtures thereof can be preferably used from the viewpoints of transparency, heat resistance, etc. Furthermore, from the viewpoint of durability, particularly preferred thermoplastic resins are acrylic resins, ester resins, and cycloolefin resins.

[0113] Suitable specific examples of binder resins include those described in WO 2016 / 190283, WO 2017 / 61337, WO 2018 / 43237, WO 2019 / 21813, and WO 2019 / 188019.

[0114] The binder resin may contain additives such as dispersants and leveling agents for stabilizing the coating film, or may contain adhesion promoters such as silane coupling agents as sheet surface modifiers. The binder resin may also contain inorganic particles such as silica particles and silicone microparticles as agents for inhibiting the precipitation of color conversion materials.

[0115] In the color-converting composition for producing a color-converting sheet of the present invention, the binder resin preferably contains, as an additional component, a hydrosilylation reaction retarder such as acetylene alcohol to inhibit curing at room temperature and thereby extend the pot life. Furthermore, the binder resin may contain, as necessary, fine particles such as fumed silica, glass powder, and quartz powder, inorganic fillers and pigments such as titanium oxide, zirconia oxide, barium titanate, and zinc oxide, flame retardants, heat resistance agents, antioxidants, dispersants, solvents, and adhesion promoters such as silane coupling agents and titanium coupling agents, within the scope of the present invention.

[0116] (Solvent) The color-changing composition of the present invention may contain a solvent in addition to the above-mentioned luminescent material and binder resin. The solvent is not particularly limited as long as it can adjust the viscosity of the resin in a fluid state and does not excessively affect the luminescence and durability of the luminescent material. Examples of such solvents include cyclohexane, hexane, toluene, 1-methoxy-2-propanol, 2-propanol, ethyl acetate, ethanol, methyl ethyl ketone, and acetone. The color-changing composition of the present invention may contain two or more of these solvents.

[0117] Among these solvents, solvents with high polarity are preferred from the viewpoint of durability of the color conversion sheet, specifically, toluene, 1-methoxy-2-propanol, 2-propanol, ethyl acetate, ethanol, methyl ethyl ketone, acetone, etc.

[0118] (Other Components) In addition to the above-mentioned light-emitting material, binder resin, and solvent, the color-converting composition of the present invention may contain other components (additives), such as a light stabilizer, an antioxidant, a processing and heat stabilizer, a light resistance stabilizer such as an ultraviolet absorber, scattering particles, silicone microparticles, and a silane coupling agent.

[0119] Examples of light stabilizers include, but are not limited to, tertiary amines, catechol derivatives, nickel compounds, and complexes or salts with organic acids containing at least one transition metal selected from the group consisting of Sc, V, Mn, Fe, Co, Cu, Y, Zr, Mo, Ag, and lanthanoids. These light stabilizers may be used alone or in combination.

[0120] Examples of the antioxidant include, but are not limited to, phenolic antioxidants such as 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-ethylphenol. These antioxidants may be used alone or in combination.

[0121] Examples of processing and heat stabilizers include, but are not limited to, phosphorus-based stabilizers such as tributyl phosphite, tricyclohexyl phosphite, triethyl phosphine, and diphenylbutyl phosphine. These stabilizers may be used alone or in combination.

[0122] Examples of the light resistance stabilizer include, but are not limited to, benzotriazoles such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole and 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole. These light resistance stabilizers may be used alone or in combination.

[0123] The scattering particles are preferably inorganic particles having a refractive index of 1.7 to 2.8, such as titania, zirconia, alumina, ceria, titanium oxide, tin oxide, indium oxide, iron oxide, zinc oxide, aluminum nitride, aluminum, tin, titanium or zirconium sulfide, and titanium or zirconium hydroxide.

[0124] In the color-changing composition of the present invention, the content of these additives varies depending on the molar absorption coefficient, luminescence quantum yield, and absorption intensity at the excitation wavelength of the compound, as well as the thickness and transmittance of the color-changing sheet to be produced, but is usually 1.0 × 10 -3 The content of these additives is preferably 1.0×10 to 30 parts by weight based on 100 parts by weight of the binder resin. -2 More preferably, the amount is 1.0×10 -1 It is particularly preferable that the amount is from 1 part by weight to 10 parts by weight.

[0125] (Substrate Layer) Examples of the substrate layer (e.g., substrate layer 10 shown in Figures 5 to 8) of the color conversion sheet of the present invention include glass and resin films. As the resin film, plastic films such as polyethylene terephthalate (PET), polyphenylene sulfide, polycarbonate, polypropylene, and polyimide are preferred. From the viewpoint of ease of peeling of the film, the surface of the substrate layer may be subjected to a release treatment in advance. There are no particular restrictions on the thickness of the substrate layer, but the lower limit is preferably 25 μm or more, and more preferably 38 μm or more. The upper limit is preferably 5000 μm or less, and more preferably 3000 μm or less.

[0126] (Barrier Film) The barrier film (for example, barrier film 12 shown in FIG. 7) of the color conversion sheet of the present invention is preferably one that suppresses the penetration of oxygen, moisture, heat, etc. into the color conversion layer. The color conversion sheet of the present invention may have two or more layers of such barrier films. Furthermore, the color conversion sheet of the present invention may have such barrier films on both sides of the color conversion layer as exemplified in FIG. 7, or may have such barrier films on only one side of the color conversion layer.

[0127] Examples of barrier films having gas barrier properties include inorganic oxides such as silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, zinc oxide, tin oxide, indium oxide, yttrium oxide, and magnesium oxide; inorganic nitrides such as silicon nitride, aluminum nitride, titanium nitride, and silicon carbonitride; metal oxide thin films or metal nitride thin films obtained by adding other elements to these; and films containing various resins such as polyvinylidene chloride, acrylic resins, silicone resins, melamine resins, urethane resins, fluorine-containing resins, and polyvinyl alcohol-based resins such as saponified vinyl acetate. The barrier film may contain two or more of these. Examples of barrier films having moisture barrier properties include films containing various resins such as polyethylene, polypropylene, nylon, polyvinylidene chloride, copolymers of vinylidene chloride and vinyl chloride, copolymers of vinylidene chloride and acrylonitrile, fluorine-containing resins, and polyvinyl alcohol-based resins such as saponified vinyl acetate.

[0128] The color conversion sheet of the present invention may further have an auxiliary layer having a light diffusion layer, an adhesive layer, an anti-reflection function, an anti-glare function, an anti-reflection and anti-glare function, a hard coat function (abrasion resistance function), an anti-static function, an anti-fouling function, an electromagnetic wave shielding function, an infrared ray blocking function, an ultraviolet ray blocking function, a polarizing function, a color-tuning function, or the like, depending on the required functions.

[0129] <Method for manufacturing a color conversion sheet> Next, an example of a method for manufacturing a color conversion sheet according to an embodiment of the present invention will be described. In this method for manufacturing a color conversion sheet, the color conversion composition prepared by the above-described method is applied to an underlayer such as a substrate layer or a barrier layer (a barrier film layer) and dried. This forms a color conversion layer. If the binder resin contained in the color conversion composition contains a thermosetting resin, the color conversion composition may be applied to an underlayer such as a substrate layer and then heat-cured to form the color conversion layer. If the binder resin contained in the color conversion composition is a photocurable resin, the color conversion composition may be applied to an underlayer such as a substrate layer and then photocured to form the color conversion layer.

[0130] The color-converting composition can be applied using a reverse roll coater, blade coater, comma coater, slit die coater, direct gravure coater, offset gravure coater, kiss coater, natural roll coater, air knife coater, roll blade coater, two-stream coater, rod coater, wire bar coater, applicator, dip coater, curtain coater, spin coater, knife coater, etc. In order to obtain a uniform thickness of the color-converting layer, application using a slit die coater, comma coater or dip coater is preferred.

[0131] The color conversion layer can be dried using a common heating device such as a hot air dryer or an infrared dryer. In this case, the heating temperature is preferably 60 to 200°C, and the heating time is preferably 2 minutes to 4 hours. It is also possible to heat and cure the color conversion layer in stages using a method such as step curing.

[0132] When the color conversion layer is formed by heat curing, a hot air oven or the like can be used as the heating device. The heating conditions for heat curing the color conversion layer can be selected depending on the binder resin. For example, the heating temperature is preferably 100°C to 300°C, and the heating time is preferably 1 minute to 2 hours.

[0133] When forming a color conversion layer by photocuring, it is preferable to irradiate the color conversion layer with high-energy light such as ultraviolet light. The light irradiation conditions for photocuring the color conversion layer can be selected depending on the binder resin. For example, the wavelength of the irradiated light is preferably 200 nm to 500 nm, and the light irradiation dose is preferably 10 mJ / cm. 2 ~10 J / cm 2 It is preferable that:

[0134] After the color conversion layer is formed, the base layer can be changed as needed. In this case, simple methods include, for example, a method of replacing the base layer using a hot plate, or a method using a vacuum laminator or a dry film laminator.

[0135] The present invention will be described below with reference to examples, but the present invention is not limited to the examples described below. First, the evaluation methods and materials such as light-emitting materials in each of the examples and comparative examples will be described.

[0136] <Calculation of Spectral Transmittance of Liquid Crystal Panel> The spectral transmittance of the liquid crystal panel used in each example and comparative example was measured as follows. First, a liquid crystal display device using a blue LED as a light source was prepared for each example and comparative example. This liquid crystal display device incorporates a liquid crystal display including a backlight unit having a blue LED (blue LED light source) as a light source and a liquid crystal panel to be measured. The liquid crystal panel to be measured is the liquid crystal panel used in each example and comparative example, and is replaced for each example and comparative example. Furthermore, the size of the display screen (display surface of the liquid crystal panel) of this liquid crystal display device is 27 inches diagonally, and the area of ​​the display screen is 0.2 m 2 is.

[0137] A power of 34 W was applied to the liquid crystal display device prepared as described above, and the input power per unit area of ​​the liquid crystal display device was 170 W / m 2 (=34W / 0.2m 2 ), thereby lighting up the blue LED light source of this liquid crystal display device. Thereafter, the emission spectrum at the center of the display screen when red, green, and blue colors were displayed from the normal direction of the display screen of this liquid crystal display device (hereinafter referred to as the emission spectrum of each color display) was measured using a spectroradiometer "SR-LEDW" (manufactured by Topcon Technohouse Corporation).

[0138] Next, the liquid crystal display device was disassembled, and the backlight unit was removed from the liquid crystal display device. 2 The blue LED light source of this backlight unit was turned on by applying a power of 1000 W. Thereafter, the emission spectrum at the center of the light exit surface of this backlight unit (hereinafter referred to as the emission spectrum at the center of the backlight unit) was measured from the normal direction of the light exit surface using a spectroradiometer "SR-LEDW" (manufactured by Topcon Technohouse Corporation).

[0139] The spectral transmittance of the liquid crystal panel to be measured was calculated by subtracting the emission spectrum of the central part of the backlight unit from the emission spectrum of each color display obtained as described above.

[0140] <Calculation of chromaticity of liquid crystal panel after light from CIE standard illuminant D65 has passed through> In calculating the chromaticity of each liquid crystal panel in each example and comparative example, the chromaticity (chromaticity coordinates in the XYZ color system of JIS Z8701) of the liquid crystal panel after light from CIE standard illuminant D65 has passed through was calculated from the spectral transmittance of the liquid crystal panel calculated by the above method, the relative spectral spectrum of CIE standard illuminant D65 shown in FIG. 9 , and the color matching functions in the XYZ color system shown in FIG. 10 .

[0141] Specifically, assuming that the color matching functions in the XYZ color system are x(λ), y(λ), and z(λ), the relative spectral spectrum of CIE standard illuminant D65 is D65(λ), and the spectral transmittance of the liquid crystal panel is P(λ), the chromaticity x of the liquid crystal panel after light of the CIE standard illuminant D65 has passed through it was calculated using the following formula:

[0142]

[0143] <Light-emitting material (a) and light-emitting material (b)> In the following examples and comparative examples, compound G-1 and compound R-1 were used as the light-emitting material (a) and the light-emitting material (b) contained in the color conversion sheet, respectively. Compound G-1 and compound R-1 are the compounds shown below. Each of these compounds G-1 and compound R-1 is an organic light-emitting material.

[0144]

[0145] <Binder Resin> In the following examples and comparative examples, the resin described in WO 2019 / 021813 (Optimas 7500 (PMMA-hydrogenated styrene copolymer manufactured by Mitsubishi Gas Chemical Company, Inc.)) was used as the binder resin contained in the color conversion sheet.

[0146] Example 1 <Fabrication of Liquid Crystal Panel and Liquid Crystal Display Device> The liquid crystal panel and liquid crystal display device of Example 1 were fabricated as follows. First, TFT elements, transparent electrodes, etc. were formed on alkali-free glass, thereby fabricating a TFT array substrate. Next, an alignment film composition was applied to a color filter substrate obtained by the method described below and the TFT array substrate under conditions such that the film thickness after curing would be 100 nm. Each alignment film composition on these substrates was irradiated vertically with linearly polarized ultraviolet light via a polarizing plate. At this time, the wavelength of the ultraviolet light was 365 nm, and the exposure dose was 1.3 J / cm. 2 Each of the alignment film compositions was subjected to photo-alignment to impart anisotropy to the alignment film compositions. After the photo-alignment, each alignment film composition was baked at 230° C. for 20 minutes. This resulted in the formation of alignment films on the color filter substrate and the TFT array substrate.

[0147] Next, a sealant incorporating microrods was printed on the TFT array substrate, and the TFT array substrate and the color filter substrate were bonded together. Next, IPS liquid crystal was injected through an injection port provided in the seal portion of the TFT array substrate, thereby forming a liquid crystal cell having a liquid crystal layer sandwiched between two alignment films and the color filter substrate. Polarizing films were then bonded to both sides of the liquid crystal cell with their polarization axes perpendicular to each other. In this way, the liquid crystal panel of Example 1 was obtained. A backlight unit (described below) was attached to the liquid crystal panel, and a TAB module, printed circuit board, and other components were also mounted, thereby producing the liquid crystal display device of Example 1.

[0148] <Preparation of Color Filter> The color filter of the liquid crystal panel of Example 1 was prepared as follows. First, a black matrix resin composition BM-1 (hereinafter referred to as BM-1 as appropriate) described below was applied to alkali-free glass so that the film thickness after curing would be 1.5 μm, and then dried under vacuum. Next, the black matrix resin composition was exposed to light at an exposure dose of 40 mJ / cm through a striped photomask with a pixel pitch of 50 μm and a black matrix width of 5 μm. ２The BM-1 was exposed to i-rays, developed with a 0.3% by mass aqueous solution of tetramethylammonium for 50 seconds, and then heat-cured at a temperature of 230° C. for 30 minutes, thereby forming a black matrix.

[0149] A red resin composition CR-1 (hereinafter referred to as CR-1) described below was applied onto the alkali-free glass partitioned by the black matrix so that the film thickness after curing would be 2.1 μm, and then dried under vacuum. Then, the composition was exposed to light at a dose of 40 mJ / cm through a 50 μm-wide striped photomask. 2 The CR-1 was exposed to i-rays of 1000 kJ / cm², developed with a 0.3% by mass aqueous solution of tetramethylammonium for 50 seconds, and then heat-cured for 30 minutes at a temperature of 230° C. This formed red pixels with a pixel pitch of 50 μm.

[0150] On the alkali-free glass partitioned by the black matrix, a blue resin composition CB-1 (hereinafter referred to as CB-1) described below was applied so that the film thickness after curing would be 5.4 μm, and then dried under vacuum. Then, the composition was exposed to light at a dose of 40 mJ / cm through a 50 μm-wide striped photomask. 2 The CB-1 was exposed to i-rays of 1000 kJ / cm², developed with a 0.3% by mass aqueous solution of tetramethylammonium for 50 seconds, and then heat-cured for 30 minutes at a temperature of 230° C. This formed blue pixels with a pixel pitch of 50 μm.

[0151] Furthermore, a green resin composition CG-1 (hereinafter referred to as CG-1) described below was applied onto the alkali-free glass partitioned by the black matrix so that the film thickness after curing would be 2.5 μm, and the CG-1 was heated and dried at a temperature of 90° C. for 10 minutes. Next, the CG-1 was exposed to light at an exposure dose of 100 mJ / cm through a 50 μm-wide striped photomask. 2The CG-1 was exposed to i-rays of 1000 kJ / cm², developed with a 0.3% by mass aqueous solution of tetramethylammonium for 60 seconds, and then heat-cured at a temperature of 230°C for 30 minutes. This resulted in the formation of green pixels with a pixel pitch of 50 µm. Thereafter, an overcoat layer was formed on the red, blue, and green pixels.

[0152] Furthermore, photosensitive resin composition K-1 (hereinafter referred to as K-1 as appropriate) described below was applied onto the overcoat layer. This K-1 was dried under reduced pressure at a temperature of 25°C and a pressure of 45 Pa for 200 seconds, then heated and dried (prebaked) at a temperature of 105°C for 10 minutes, and then cooled to room temperature. This formed a prebaked film. Next, using an FX-65S (Nikon Corporation) lens scanning exposure device, ultraviolet light containing wavelengths of i-line: 365 nm, h-line: 405 nm, and g-line: 436 nm was irradiated through a circular photomask with a diameter of 7 μm, at an intensity of 60 mJ / cm. 2 The prebaked film was exposed to an exposure dose (i-line equivalent) of 1000 uF. Next, the exposed prebaked film was shower-developed for 60 seconds using a 23°C aqueous solution containing 0.3 mass% TMAH and 0.3 mass% A-60 as a developer, and then rinsed with water to drain the solution. Finally, the prebaked film was heated and dried (post-baked) for 30 minutes in an oven at 230°C to produce a color filter (color filter of Example 1) having photospacers with an upper base of 6 μm, a lower base of 9 μm, and a height of 7 μm.

[0153] [Preparation of Black Matrix Resin Composition] The black matrix resin composition used in the color filter of Example 1 was prepared as follows. First, 150 g of carbon black (MA100 manufactured by Mitsubishi Chemical Corporation), 75 g of a polymer dispersant (BYK® 6919 manufactured by BYK-Chemie, 60% by weight solution), 100 g of Cyclomer® P(ACA)Z250 (45% by weight solution of dipropylene glycol monomethyl ether, acid value 110 mg KOH / g, molecular weight 20,000), and 675 g of propylene glycol monomethyl ether acetate (PMA) were mixed to prepare a slurry. The beaker containing this slurry was connected to a Dyno-Mill via a tube, and dispersion treatment was carried out for 8 hours at a peripheral speed of 14 m / s using zirconia beads with a diameter of 0.5 mm as media. This resulted in a black matrix dispersion.

[0154] 56.54 g of the obtained black matrix dispersion liquid, 3.14 g of "Cyclomer" P(ACA)Z250, 2.64 g of DPHA monomer ("Kayarad" (registered trademark) DPHA manufactured by Nippon Kayaku Co., Ltd.) as a polymerizable compound, 0.330 g of photopolymerization initiator ("ADEKA Arcles" (registered trademark) NCI-831 manufactured by ADEKA Corporation), 0.04 g of surfactant ("BYK" (registered trademark)-333 manufactured by BYK-Chemie (hereinafter referred to as BYK-333)), 0.01 g of polymerization inhibitor (tert-butylcatechol (TBC) manufactured by DIC Corporation), and 37.30 g of PMA were added and mixed. This produced black matrix resin composition BM-1 as a resin composition for a black matrix.

[0155] [Preparation of Red Resin Composition] The red resin composition used in the color filter of Example 1 was prepared as follows. First, 150 g of C.I. Pigment Red 177 ("Chromophtal" Red (registered trademark) A2B, manufactured by Ciba Specialty Chemicals Co., Ltd.), 75 g of "BYK" 6919, 100 g of "Cyclomer" P(ACA)Z250, and 675 g of PMA were added and mixed to prepare a slurry. The beaker containing this slurry was connected to a Dyno-Mill via a tube, and dispersion treatment was carried out for 8 hours at a peripheral speed of 14 m / s using zirconia beads with a diameter of 0.5 mm as media. This resulted in a red dispersion. Next, 56.54 g of the red dispersion obtained above, 3.14 g of "Cyclomer" P(ACA)Z250, 2.64 g of DPHA monomer, 0.330 g of photopolymerization initiator (NCI-831), 0.04 g of surfactant (BYK-333), 0.01 g of polymerization inhibitor (TBC), and 37.30 g of PMA were added and mixed, thereby producing red resin composition CR-1.

[0156] [Preparation of Blue Resin Composition] The blue resin composition used in the color filter of Example 1 was prepared as follows. First, 150 g of C.I. Pigment Blue 15:6 (EP193 manufactured by DIC Corporation), 75 g of "BYK" 6919, 100 g of "Cyclomer" P(ACA)Z250, and 675 g of PMA were added and mixed to prepare a slurry. The beaker containing this slurry was connected to a Dyno-Mill via a tube, and dispersion treatment was carried out for 8 hours at a peripheral speed of 14 m / s using zirconia beads with a diameter of 0.5 mm as media. This resulted in a blue dispersion. 29.02 g of the obtained blue dispersion was added to 12.70 g of Cyclomer P(ACA)Z250, 4.68 g of DPHA monomer, 0.585 g of photopolymerization initiator (NCI-930), 0.04 g of surfactant (BYK-333), 0.01 g of polymerization inhibitor (TBC), and 52.96 g of PMA, and mixed to produce blue resin composition CB-1.

[0157] [Preparation of Green Resin Composition] The green resin composition used in the color filter of Example 1 was prepared as follows. First, 105 g of C.I. Pigment Green 59 (FASTGEN Green C100), 70 g of C.I. Pigment Yellow 45 (Clariant "Hostaperm" Yellow HN4G), 75 g of polymer dispersant ("BYK" 6919), 100 g of binder resin ("ADEKA ARCLES" WR301), and 675 g of PMA were added and mixed to prepare a slurry. The beaker containing this slurry was connected to a Dyno Mill via a tube, and dispersion treatment was carried out for 8 hours at a peripheral speed of 14 m / s using zirconia beads with a diameter of 0.5 mm as media. This resulted in a Pigment Green 59 dispersion.

[0158] 47.361 g of the obtained Pigment Green 59 dispersion, 1.111 g of WR301, and DPHA monomer ("Kayarad" (registered trademark) DPHA manufactured by Nippon Kayaku Co., Ltd.) were mixed together. Acid value 0.1 mg KOH / g) 1.863 g, photopolymerization initiator (ADEKA Corporation "ADEKA ARCLES" (registered trademark) NCI-831) 0.192 g, chain transfer agent (Showa Denko K.K. "KARENZ" (registered trademark) MT-PE1) 0.021 g, adhesion improver (Shin-Etsu Chemical Co., Ltd. KBM-503) 0.160 g, surfactant (BYK-333) 0.040 g, polymerization inhibitor (DIC Corporation tertiary butyl catechol (TBC)) 0.009 g, PMA 7.243 g, dipropylene glycol monomethyl ether acetate (DPMA) 42.001 g, was added and mixed. Thereby, a green resin composition CG-1 was prepared.

[0159] [Preparation of Photosensitive Resin Composition] The photosensitive resin composition used in the color filter of Example 1 was prepared as follows. First, 95.3 g of methacrylic acid (MA), 3.0 g of 2,2'-azobis(2-methylbutyronitrile), 0.5 g of lauryl mercaptan, and 239 g of 3-methoxy-1-butanol solution were charged into a polymerization vessel and stirred at 90°C for 2 hours under a nitrogen atmosphere. The temperature of the mixture was then raised to 100°C, and the mixture was heated and stirred for an additional 5 hours to allow the reaction to proceed. Next, the atmosphere in the polymerization vessel was purged with air, and 143.7 g of glycidyl methacrylate (GMA), 1.2 g of dimethylbenzylamine, and 0.2 g of p-methoxyphenol were added to the resulting reaction solution and stirred at 110°C for 6 hours. Subsequently, 3-methoxy-1-butanol was added to the reaction solution to obtain an alkali-soluble resin solution with a solids concentration of 40.0% by mass.

[0160] Next, 50.07 parts by mass of the obtained alkali-soluble resin solution, 8.58 parts by mass of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate ("KAYARAD" (registered trademark) DPHA; manufactured by Nippon Kayaku Co., Ltd.), 0.18 parts by mass of the photopolymerization initiator "ADEKA ARCLES" (registered trademark) N-1919, and 0.2 parts by mass of "IRGACURE" (registered trademark) 907 (manufactured by BASF Japan Ltd.) were mixed. 7 parts by mass of 2,4-diethylthioxanthone ("KAYACURE" (registered trademark) DETX-S; manufactured by Nippon Kayaku Co., Ltd.), 0.45 parts by mass of a surfactant (BYK-333), 0.11 parts by mass of a polymerization inhibitor 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone (manufactured by Wako Pure Chemical Industries, Ltd.), and 40 parts by mass of propylene glycol monomethyl ether (PMA) were mixed and stirred at room temperature. Photosensitive resin composition K-1 was thus prepared.

[0161] <Preparation of Color Conversion Sheet> The color conversion sheet of Example 1 was prepared as follows. First, 0.90 parts by weight of compound G-1, which is the luminescent material (a), and 300 parts by weight of ethyl acetate as a solvent were mixed with 100 parts by weight of a binder resin (Optimas 7500). Thereafter, this mixture was stirred and degassed at 1000 rpm for 20 minutes using a planetary stirring and degassing device "Mazerustar (registered trademark) KK-400" (manufactured by Kurabo Industries, Ltd.). This resulted in a green color conversion composition as a resin liquid for preparing a green color conversion layer.

[0162] Next, 0.05 parts by weight of compound R-1, which is the light-emitting material (b), and 300 parts by weight of ethyl acetate as a solvent were mixed with 100 parts by weight of binder resin (Optimas 7500). Thereafter, this mixture was stirred and degassed for 20 minutes at 1000 rpm using a planetary stirring and degassing device "Mazerustar (registered trademark) KK-400" (manufactured by Kurabo Industries, Ltd.). This resulted in a red color conversion composition as a resin liquid for producing a red color conversion layer.

[0163] Next, "Vylon 630" (a polyester resin manufactured by Toyobo Co., Ltd.) was used as the binder resin, and 300 parts by weight of ethyl acetate was mixed with 100 parts by weight of this polyester resin as a solvent. Thereafter, this mixture was stirred and degassed at 300 rpm for 20 minutes using a planetary stirring and degassing device "Mazerustar (registered trademark) KK-400" (manufactured by Kurabo Industries, Ltd.). This yielded a resin composition for the adhesive layer.

[0164] Next, the green color conversion composition was applied to a polyester film "Lumirror" (registered trademark) U48 (manufactured by Toray Industries, Inc., thickness 50 μm) using a slit die coater, and dried by heating at 120° C. for 20 minutes, thereby forming a green color conversion layer unit with an average film thickness of 20 μm.

[0165] Similarly, the red color conversion composition was applied to the PET substrate layer side of a light diffusing film "Chemical Matte" 125PW (manufactured by Kimoto Co., Ltd., thickness 138 μm) using a slit die coater, and then heated and dried at 120° C. for 20 minutes, thereby forming a red color conversion layer with an average thickness of 20 μm.

[0166] Furthermore, the resin composition for the adhesive layer was applied using a slit die coater onto the red color conversion layer formed on the PET substrate layer side of a light diffusion film "Chemical Matte" 125PW (manufactured by Kimoto Co., Ltd., thickness 138 μm), and then heated and dried for 20 minutes at 120° C. This formed a unit having an adhesive layer with an average thickness of 10 μm on the red color conversion layer.

[0167] Next, the above two units were heat-laminated so that the green color conversion layer and the adhesive layer were directly laminated together to produce a color conversion sheet (the color conversion sheet of Example 1) with a laminated structure of "substrate layer / green color conversion layer / adhesive layer / red color conversion layer / light diffusion film."

[0168] <Fabrication of Backlight Unit> The backlight unit of Example 1 was fabricated as follows. First, a liquid crystal display device using a blue LED as a light source was disassembled, and the backlight unit was removed from the liquid crystal display device. This liquid crystal display device had a display screen size of 27 inches diagonally and an area of ​​0.2 m². 2 The backlight unit removed was an edge type, with a reflector below the light guide plate, and a color conversion sheet, a prism sheet, and a reflective polarizing sheet above the light guide plate. The color conversion sheet located between the light guide plate and the prism sheet of this backlight unit was replaced with the color conversion sheet of Example 1 prepared as described above, and the backlight unit of Example 1 was thereby produced.

[0169] <Evaluation of chromaticity of backlight unit> In the evaluation of chromaticity of the backlight unit of Example 1, the backlight unit obtained as described above (area of ​​display screen = 0.2 m 2 ) or 170 W / m 2The area of ​​the display screen was the same as the area of ​​the light exit surface of the backlight unit that emits light to the display screen of the liquid crystal display device (area of ​​the color conversion sheet). By applying the above power, the light source (blue LED light source) of the backlight unit was turned on, and the initial chromaticity x0 and emission spectrum of the center of the backlight unit were measured from the normal direction of the light exit surface of the backlight unit using a spectroradiometer "SR-LEDW" (manufactured by Topcon Technohouse Corporation). This chromaticity x0 is the initial chromaticity at the center of the light exit surface of the backlight unit. Thereafter, the backlight unit was placed in a thermostat "PV-222" (manufactured by Espec Corporation) at 50°C, and the backlight unit in this 50°C temperature environment was heated to 34 W of power, i.e., 170 W / m 2 The backlight unit was left standing for 2000 hours with a power of 170 W / m applied, and then removed from the thermostat. 2 A power of 1000 W was applied to the backlight unit. This turned on the blue LED light source of the backlight unit, and the chromaticity x1 and emission spectrum of the central part of the backlight unit after 2000 hours had passed were measured. This chromaticity x1 is the chromaticity (chromaticity over time) at the central part of the light exit surface of the backlight unit after 2000 hours had passed. The initial emission spectrum and the emission spectrum after 2000 hours of the central part of the backlight unit in Example 1 were as shown in FIG. 11 .

[0170] <Evaluation of chromaticity of liquid crystal display> In the evaluation of chromaticity of the liquid crystal display of Example 1, a liquid crystal panel having the spectral transmittance shown in FIG. 12 was used as the liquid crystal panel of Example 1. The spectral transmittance of this liquid crystal panel was measured by the method described above. In addition, for the liquid crystal panel of Example 1, the chromaticity x2 of the liquid crystal panel after light of CIE standard illuminant D65 passed through it was calculated by the method described above. As a result, this chromaticity x2 was 0.335.

[0171] For the liquid crystal display of Example 1 using this liquid crystal panel and the backlight unit, the chromaticity coordinates in the XYZ color system of JIS Z8701 were calculated from the initial emission spectrum and the emission spectrum after 2000 hours at the center of the backlight unit shown in FIG. 11, the spectral transmittance of the liquid crystal panel shown in FIG. 12, and the color matching functions in the XYZ color system. A and chromaticity x after 2000 hours B When each was calculated, the chromaticity x A is 0.307, and the chromaticity x B The chromaticity x A (Initial chromaticity x A (also called) and the above chromaticity x B (chromaticity over time x B chromaticity change x between the initial state and after 2000 hours of use of the liquid crystal display in Example 1. B -x A The evaluation result of the liquid crystal display in Example 1 is shown in Table 1 below.

[0172] Example 2 In Example 2, a color conversion sheet, a backlight unit, and a liquid crystal display were produced and evaluated in the same manner as in Example 1, except that the red resin composition used in the color filter had a film thickness of 2.3 μm after curing, the blue resin composition had a film thickness of 4.7 μm after curing, and the liquid crystal panel included in the liquid crystal display had a spectral transmittance shown in FIG. 13 . The liquid crystal panel of Example 2 had a chromaticity x2 of 0.322 after light of CIE standard illuminant D65 passed through it. The configuration and evaluation results of the liquid crystal display in Example 2 are shown in Table 1.

[0173] Example 3 In Example 3, a color conversion sheet and a backlight unit were produced in the same manner as in Example 2, except that the content of compound G-1, the luminescent material (a) contained in the green color conversion composition of the color conversion sheet, was set to 0.49 parts by weight per 100 parts by weight of the binder resin. The initial emission spectrum and the emission spectrum after 2000 hours at the center of the backlight unit in Example 3 were as shown in FIG. 14. Using this backlight unit and a liquid crystal panel having the spectral transmittance shown in FIG. 13, a liquid crystal display was produced and various evaluations were carried out in the same manner as in Example 1. The configuration and evaluation results of the liquid crystal display in Example 3 are shown in Table 1.

[0174] Example 4 In Example 4, a color conversion sheet, a backlight unit, and a liquid crystal display were produced and evaluated in the same manner as in Example 1, except that the red resin composition used in the color filter had a film thickness of 3.8 μm after curing, the blue resin composition had a film thickness of 2.5 μm after curing, and the liquid crystal panel included in the liquid crystal display had a spectral transmittance shown in FIG. 15 . The liquid crystal panel of Example 4 had a chromaticity x2 of 0.250 after light of CIE standard illuminant D65 passed through it. The configuration and evaluation results of the liquid crystal display in Example 4 are shown in Table 1.

[0175] Example 5 In Example 5, a color conversion sheet, a backlight unit, and a liquid crystal display were produced and evaluated in the same manner as in Example 1, except that the red resin composition used in the color filter had a film thickness of 6.0 μm after curing, the blue resin composition had a film thickness of 2.5 μm after curing, and the liquid crystal panel included in the liquid crystal display had a spectral transmittance shown in FIG. 16 . The chromaticity x2 of the liquid crystal panel of Example 5 after light of CIE standard illuminant D65 was transmitted through the liquid crystal panel was 0.230. The configuration and evaluation results of the liquid crystal display in Example 5 are shown in Table 1.

[0176] Comparative Example 1 In Comparative Example 1, a color conversion sheet, a backlight unit, and a liquid crystal display were produced and evaluated in the same manner as in Example 1, except that the red resin composition used in the color filter had a film thickness of 2.0 μm after curing, the blue resin composition had a film thickness of 6.5 μm after curing, and the liquid crystal panel included in the liquid crystal display had a spectral transmittance shown in FIG. 17 . The liquid crystal panel of Comparative Example 1 had a chromaticity x2 of 0.358 after light of CIE standard illuminant D65 passed through it. The configuration and evaluation results of the liquid crystal display in Comparative Example 1 are shown in Table 1.

[0177] The results of Examples 1 to 5 and Comparative Example 1 show that by setting the chromaticity x2 of the liquid crystal panel after CIE standard illuminant D65 light has passed through it to 0.335 or less, it is possible to suppress changes in the chromaticity x of the liquid crystal display after the blue LED light source of the backlight unit has been turned on for 2000 hours in a temperature environment of 50° C. In Examples 1 to 5, by relatively lowering the transmittance of red region light with a wavelength of 580 nm or more and 750 nm or less in the liquid crystal panel compared to Comparative Example 1, it is possible to suppress changes in the chromaticity x of the backlight unit and extend the chromaticity change life of the liquid crystal display.

[0178]

[0179] As described above, the liquid crystal display according to the present invention is useful for suppressing chromaticity changes in liquid crystal displays after long-term use, and is particularly suitable for liquid crystal displays that can suppress chromaticity changes even if the chromaticity of the backlight unit changes due to long-term use.

[0180] 1A, 1B, 1C, 1D Color conversion sheet 10 Base layer 11 Color conversion layer 12 Barrier film 2 Backlight unit 21 Blue LED light source 22 Reflector 23 Light guide plate 24 Diffusion sheet 25 Color conversion sheet 26 Prism sheet 27 Reflective polarizing sheet 3 Liquid crystal panel 31 First glass layer 32 First polarizing film 33 First alignment film 34 Liquid crystal layer 35 Second alignment film 36 Color filter 37 Second polarizing film 38 Second glass layer 4 Liquid crystal display 40 Liquid crystal display device 41 Main body 42 Stand 43 Display screen

Claims

1. A liquid crystal display comprising a backlight unit having a blue LED light source and a color conversion sheet, and a liquid crystal panel, wherein the initial chromaticity of the backlight unit is x0, and the input power per unit area of ​​the liquid crystal display in a temperature environment of 50°C is 170 W / m 2 a relationship between x0 and x1 satisfies 0.001≦|x1-x0|≦0.020, wherein x1 is the chromaticity of the backlight unit after the blue LED light source is turned on for 2000 hours under the above conditions, the color conversion sheet contains at least a luminescent material and a binder resin, and x2 is the chromaticity of the liquid crystal panel after light of CIE standard light source D65 is transmitted through the liquid crystal panel, wherein x2 is 0.335 or less.

2. The liquid crystal display according to claim 1, wherein the relationship between x1 and x0 of the backlight unit is -0.020≦x1-x0≦-0.

001.

3. The liquid crystal display according to claim 1, wherein the light-emitting material is an organic light-emitting material.

4. The liquid crystal display according to claim 1, wherein the luminescent material contains a compound represented by the following general formula (1): (In the general formula (1), X is C-R 7 Or N. 1 ~R 9 may be the same or different, and are selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen atom, a cyano group, an aldehyde group, a carbonyl group, a carboxy group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group, and a condensed ring or an aliphatic ring formed between adjacent substituents.

5. The liquid crystal display according to claim 1, wherein the luminescent material is at least one of the following luminescent materials (a) and (b): Luminescent material (a): an organic luminescent material that emits light with a peak wavelength observed in the region of 500 nm or more and less than 580 nm when excited with excitation light with a wavelength range of 430 nm or more and 500 nm or less; Luminescent material (b): an organic luminescent material that emits light with a peak wavelength observed in the region of 580 nm or more and 750 nm or less when excited with at least one of excitation light with a wavelength range of 430 nm or more and 500 nm or less and the emission from the luminescent material (a).

6. The content of the light-emitting material contained per unit area of ​​the color conversion sheet is 0.12 g / m 2 The liquid crystal display according to claim 1, characterized in that 7. The liquid crystal display according to claim 1, wherein the x2 after the light of the CIE standard illuminant D65 is transmitted is 0.230 or more and 0.335 or less.

8. The liquid crystal display according to claim 1, wherein the x2 after the light of the CIE standard illuminant D65 is transmitted is 0.250 or more and 0.335 or less.

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