Color conversion sheet and backlight unit including same

Abstract

A color conversion sheet according to one embodiment of the present invention comprises: a wavelength conversion layer in which an organic phosphor is dispersed in a resin matrix; and a light absorption layer in which an organic light absorber on one surface of the wavelength conversion layer is dispersed in a binder resin, thereby absorbing short-wavelength blue light that may deteriorate an organic phosphor included in the wavelength conversion layer without affecting light emission characteristics of the organic phosphor, therefore, the organic phosphorescent body which is safe to the environment is adopted, the excellent color gamut and brightness characteristics are achieved at the same time, low color change and excellent brightness reliability are shown during light irradiation not only at normal temperature but also in a high-temperature environment, and excellent performance is achieved in the aspect of eyesight protection.

Description

Technical Field

[0001] The present invention relates to a color conversion sheet using an organic phosphor and a backlight unit including the same, and more specifically, to a color conversion sheet having a light-absorbing layer and a backlight unit including the same. Background Technology

[0002] Typically, liquid crystal display (LCD) devices are non-emitting display devices. They do not emit light themselves and therefore cannot form images. Instead, they require external light to be incident on them to form images. Therefore, a backlight unit (BLU) is required on the back of such LCD devices.

[0003] Recently, quantum dot technology has been widely used to achieve high-definition images in liquid crystal displays. The advantages of quantum dot technology include the ability to achieve multiple colors simply by adjusting the size of nanoscale inorganic particles, and its excellent stability against ultraviolet (UV) light. However, existing cadmium (Cd) nanoscale inorganic particles have disadvantages due to environmental concerns and the fact that they are vulnerable to moisture and require the use of a barrier film. These disadvantages include limitations in substrate selection and combination with other optical films.

[0004] To address these issues, an organic phosphor is being developed that achieves a wide color gamut and excellent brightness characteristics without incorporating cadmium-based nanoscale inorganic particles. Compared to nanoscale inorganic particles used in quantum dot technology, organic phosphors offer superior luminescent efficiency and have the following advantages: even using the same phosphor, a variety of luminescent properties can be exhibited through variations in surrounding chemicals. Furthermore, organic phosphors are relatively moisture-resistant, require no blocking film, and are compatible with various substrates and easily combined with other optical films.

[0005] However, while organic phosphors absorb light from the blue LEDs of a display and emit light, they degrade due to the presence of short-wavelength blue light that cannot be absorbed, thus reducing the display's light durability. Furthermore, since short-wavelength blue light can reach the human retina, causing retinal dysfunction and vision loss, there is a need to develop a technology to eliminate short-wavelength blue light. Summary of the Invention

[0006] The problem to be solved The present invention is proposed to solve the problems mentioned above and to address existing requirements. The problem to be solved by the present invention is to provide a color conversion sheet and a backlight unit including the color conversion sheet, which absorbs short-wavelength blue light that would degrade the organic phosphor without affecting the light emission characteristics of the organic phosphor included in the wavelength conversion layer. Therefore, while using an environmentally safe organic phosphor, it has excellent color gamut and brightness characteristics, exhibiting low color change and excellent brightness reliability not only at room temperature but also under light irradiation in high-temperature environments, and has excellent performance in terms of vision protection.

[0007] The above and other objects and advantages of the present invention will become more apparent from the following description of preferred embodiments.

[0008] means for solving problems The objective is achieved by a color conversion sheet comprising: a wavelength conversion layer in which an organic phosphor is dispersed in a resin matrix; and a light-absorbing layer located on one surface of the wavelength conversion layer, wherein the organic light-absorbing material is dispersed in an adhesive resin. The light-absorbing layer blocks more than 60% of wavelengths below 410 nm, blocks more than 10% of wavelengths above 430 nm, and transmits more than 80% of wavelengths above 460 nm.

[0009] Preferably, the light-absorbing layer can have the maximum emission peak in the wavelength range of 440nm to 470nm. When single-mode light with a full width at half maximum (FWHM) of less than 40nm is incident, the light transmitted from the color conversion sheet can satisfy the following equation 1.

[0010] (Equation 1) T1 / B1≥0.6 B1: Luminous intensity at the maximum emission peak of the incident light. T1: Luminous intensity at the maximum emission peak of transmitted light.

[0011] Preferably, the light-absorbing layer can have the maximum emission peak in the wavelength range of 440nm to 470nm. When single-mode light with a full width at half maximum (FWHM) of less than 40nm is incident, the light transmitted from the color conversion sheet can satisfy the following equation 2.

[0012] (Equation 2) TS1 / TS2≤0.9 TS1: The luminous intensity of transmitted light at the position with the relatively shorter wavelength among the two positions where the incident light reaches half its maximum luminous intensity. TS2: The luminous intensity of transmitted light at the position with the relatively longer wavelength between the two positions where the incident light reaches half its maximum luminous intensity.

[0013] Preferably, the organic light absorber may include at least one selected from anthracene, tetraphenylene, coumarins, porphyrins, diazaporphyrins, pyrrole methylene, and benzotriazoles.

[0014] Preferably, the adhesive resin of the light-absorbing layer may include at least one resin selected from esters, olefins, acrylics, ethers, carbamates, carbonates, silicones and epoxy resins.

[0015] Preferably, the light-absorbing layer may contain 0.1 to 40 parts by weight of organic light absorber relative to 100 parts by weight of adhesive resin.

[0016] Preferably, the light-absorbing layer may further include at least one selected from UV absorbers, UV stabilizers, and antioxidants.

[0017] Preferably, the organic phosphor may include at least one of green organic phosphor and red organic phosphor.

[0018] Preferably, the resin matrix of the wavelength conversion layer may include at least one resin selected from esters, olefins, acrylics, ethers, carbamates, carbonates and imides.

[0019] Preferably, the wavelength conversion layer may include 0.0001 to 10 parts by weight of an organic phosphor, relative to 100 parts by weight of the resin matrix.

[0020] Preferably, the resin matrix of the wavelength conversion layer may have a glass transition temperature (Tg) of 50°C to 150°C.

[0021] Preferably, under a temperature of 60°C, after 100 hours, the change in the brightness L value of the color conversion sheet can be less than 1%.

[0022] Preferably, the light-absorbing layer may be located in the direction that the light irradiates the wavelength conversion layer.

[0023] Preferably, it may further include a first polyester substrate layer located on another surface of the wavelength conversion layer.

[0024] Preferably, it may further include a second polyester substrate layer located between the wavelength conversion layer and the light-absorbing layer or on the surface of the light-absorbing layer.

[0025] In addition, the objective is achieved by a backlight unit, which includes the color conversion sheet described above.

[0026] Invention Effects According to the color conversion sheet and backlight unit including the present invention, the color conversion sheet further includes a light-absorbing layer on one surface of the wavelength conversion layer in which an organic phosphor is dispersed. The light-absorbing layer absorbs short-wavelength blue light irradiated from a blue LED, thereby preventing the organic phosphor from deteriorating due to high-energy short-wavelength blue light, thus having the effect of solving problems such as color coordinate changes or reliability degradation.

[0027] In addition, according to the color conversion sheet and the backlight unit including the present invention, the light-absorbing layer only absorbs short-wavelength blue light that does not affect the luminescence characteristics of the organic phosphor, thereby having the following effects: it can solve the problem of brightness characteristic changes and color changes caused by the absorption of blue light by organic phosphors, and can also solve the problem of vision decline caused by blue light.

[0028] However, the effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view of a color conversion sheet according to an embodiment of the present invention.

[0030] Figure 2 This is a cross-sectional view of a color conversion sheet according to another embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of a backlight unit including a color conversion sheet according to an embodiment of the present invention. Detailed Implementation

[0032] In the following description, embodiments of the present invention will be described in detail with reference to the accompanying drawings to enable those skilled in the art to implement them. The present invention should not be construed as limited to the embodiments set forth herein, and may be embodied in many different forms.

[0033] In the accompanying drawings, for clarity of illustration, parts irrelevant to the description have been omitted, and the same or similar reference numerals are used for the same constituent elements throughout the specification. Additionally, in the drawings, the thickness of layers and regions has been exaggerated for clarity. Furthermore, in this specification, when referring to a constituent element being disposed "on" or "above" another constituent element, the constituent element may be directly disposed on the other constituent element, or other constituent elements may exist between the constituent elements. Conversely, when referring to a constituent element being directly disposed "on" or "above" another constituent element, other constituent elements may not exist.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, this specification (including definitions) shall prevail. Furthermore, while similar or equivalent methods and materials may be used in the implementation or testing of this invention, suitable methods and materials are described herein.

[0035] In this specification, "~ type resin", "~ type polymer" and / or "~ type copolymer" are broad concepts that include all "~ type resin", "~ type polymer", "~ type copolymer" and / or "~ type resin, polymer or copolymer derivatives". Additionally, in this specification, the term "polymer or copolymer crosslinked from these resins" means "polymer or copolymer crosslinked from the aforementioned resins".

[0036] In this specification, the term "compound" is used in a broad sense, including all "monoatomic molecules", "oligomers", and "polymeric compounds, including homopolymers and copolymers".

[0037] In this specification, unless otherwise expressly stated, the term "comprising" means that other constituent elements may be included, but are not excluded.

[0038] In this specification, the term "combination of them" refers to a mixture or combination of more than one of the constituent elements described.

[0039] In this specification, the term "and / or" refers to any combination and all combinations of more than one item described herein. In this specification, the term "or" means "and / or". In this specification, the expression "at least one" or "more than one" preceding a constituent element supplements the entire list of constituent elements, rather than supplementing a single constituent element in the description.

[0040] Unless otherwise stated in this specification, all percentages, parts, and ratios are based on weight. Furthermore, when a quantity, concentration, or other value or parameter is given as any one of the categories of ranges, preferred ranges, or preferred upper and lower limits, it should be understood that, regardless of whether the range is disclosed individually, all ranges formed by any pair of any upper or preferred range limit and any lower or preferred range limit are specifically disclosed.

[0041] When a range of numerical values ​​is mentioned in this specification, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. The scope of this invention is not intended to be limited to the specific values ​​mentioned when defining the range. In this specification, each constituent element includes both singular and plural concepts.

[0042] The color change sheet of the present invention will be described in detail below with reference to the accompanying drawings.

[0043] Reference Figure 1 This is a cross-sectional view of a color conversion sheet according to an embodiment of the present invention. The color conversion sheet 100 of an embodiment of the present invention includes: a wavelength conversion layer 10, wherein an organic phosphor is dispersed in a resin matrix; and a light-absorbing layer 20, located on one surface of the wavelength conversion layer 10, wherein the organic light-absorbing material is dispersed in an adhesive resin. In this case, the light-absorbing layer 20 can be formed on one surface of the wavelength conversion layer 10 by coating or printing a light-absorbing composition.

[0044] In one embodiment, the light-absorbing layer 20 transmits the blue light required for the organic phosphor of the wavelength conversion layer 10 to emit light while blocking unwanted high-energy short-wavelength blue light during the emission process, thereby preventing the organic phosphor of the wavelength conversion layer 10 from deteriorating due to short-wavelength blue light. Furthermore, the light-absorbing layer 20 also functions to prevent the organic phosphor within the wavelength conversion layer 10 from deteriorating due to unwanted factors such as moisture and oxygen in the air when the wavelength conversion layer 10 is exposed to the outside. In addition, by blocking unwanted high-energy short-wavelength blue light during the emission process of the organic phosphor of the wavelength conversion layer 10, the light-absorbing layer 20 not only prevents color changes and brightness degradation of the display but also addresses the problem of vision loss caused by blue light emitted during prolonged display use.

[0045] To achieve the function of the light-absorbing layer 20 as described above, in this invention, preferably, the light-absorbing layer 20 blocks at least 60% of wavelengths below 410 nm, blocks at least 10% of wavelengths above 430 nm, and transmits at least 80% of wavelengths above 460 nm. More preferably, the light-absorbing layer 20 blocks at least 70% of wavelengths below 410 nm, blocks at least 20% of wavelengths above 430 nm, and transmits at least 90% of wavelengths above 460 nm.

[0046] This is because when the light-absorbing layer 20 blocks less than 60% of the wavelength region below 410nm and less than 10% of the wavelength region below 430nm, the organic phosphor of the wavelength conversion layer 10 deteriorates over time due to the high-energy short-wavelength blue light, leading to changes in color coordinates and a decrease in reliability. The unblocked short-wavelength blue light passes through the liquid crystal of the display and reaches the human eye, which can cause problems such as decreased vision.

[0047] Conversely, when the light-absorbing layer 20 transmits less than 80% of the wavelength region above 460 nm, the amount of light required for the organic phosphor of the wavelength conversion layer 10 to emit light will decrease, which can reduce the luminous efficiency of the organic phosphor. In addition, this is because when the light-absorbing layer 20 transmits less than 80% of the wavelength region above 460 nm, the green or red light in the portion of the light emitted in the organic phosphor of the wavelength conversion layer 10 and recycled by the optical sheet is absorbed by the light-absorbing layer 20, resulting in color changes and reduced brightness characteristics.

[0048] In addition, preferably, the light-absorbing layer 20 has a luminous intensity that satisfies Equations 1 and 2 below.

[0049] First, preferably, the light-absorbing layer 20 has a maximum emission peak in the wavelength range of 440 nm to 470 nm, and when monomodal light with a full width at half maximum (FWHM) of less than 40 nm is incident, the transmitted light has optical characteristics that satisfy Equation 1 below.

[0050] (Equation 1) T1 / B1≥0.6 B1: Luminous intensity at the maximum emission peak of the incident light. T1: Luminous intensity at the maximum emission peak of transmitted light.

[0051] As shown in Equation 1, the ratio of the luminous intensity at the maximum emission peak of the light incident on the light-absorbing layer 20 to the luminous intensity at the maximum emission peak of the transmitted light is preferably 0.6 or higher. This is because when the ratio is less than 0.6, there is more absorption not only in the short-wavelength blue light region, but also in the long-wavelength blue light region above 440 nm required for the organic phosphor to emit light in the wavelength conversion layer 10, which can significantly reduce the luminous efficiency of the organic phosphor.

[0052] In addition, preferably, the light-absorbing layer 20 has a maximum emission peak in the wavelength range of 440 nm to 470 nm, and when single-mode light with a full width at half maximum (FWHM) of less than 40 nm is incident, the transmitted light has optical characteristics that satisfy the following formula 2.

[0053] (Equation 2) TS1 / TS2≤0.9 TS1: The luminous intensity of transmitted light at the position with the relatively shorter wavelength among the two positions where the incident light reaches half its maximum luminous intensity. TS2: The luminous intensity of transmitted light at the position with the relatively longer wavelength between the two positions where the incident light reaches half its maximum luminous intensity.

[0054] That is, in Equation 2, at the two positions serving as the reference for the full width at half maximum (FWHM), TS1 and TS2 represent the luminous intensity of transmitted light at the relatively shorter wavelength position (TS1) and the luminous intensity of transmitted light at the relatively longer wavelength position (TS2), respectively. For example, when the maximum luminous intensity of the incident light is located at a wavelength of 460 nm and the FWHM is 20 nm, TS1 represents the luminous intensity at a wavelength of 450 nm, and TS2 represents the luminous intensity at a wavelength of 470 nm. In addition, when the maximum luminous intensity of the incident light is located at a wavelength of 450 nm and the FWHM is 10 nm, TS1 represents the luminous intensity at a wavelength of 445 nm, and TS2 represents the luminous intensity at a wavelength of 455 nm.

[0055] As shown in Equation 2, the difference in luminous intensity of transmitted light between the short-wavelength position and the long-wavelength position corresponding to half the maximum luminous intensity of light incident on the light-absorbing layer 20 is preferably 0.9 or less, more preferably 0.8 or less. This is because the light-absorbing layer 20 blocks short-wavelength blue light and selectively transmits long-wavelength blue light, thereby preventing the degradation of the organic phosphor contained in the wavelength conversion layer 10 and also preventing a decrease in luminous efficiency. Conversely, when Equation 2 exceeds 0.9, it is difficult to expect the light-absorbing layer 20 to block short-wavelength blue light, and when it exceeds 1.0, the blocking of long-wavelength blue light required for the luminous emission of the organic phosphor is greater than the blocking of short-wavelength blue light, thereby significantly reducing the luminous efficiency of the organic phosphor.

[0056] Preferably, in one embodiment of the present invention, the organic light absorber of the light-absorbing layer 20 includes at least one selected from anthracene, tetraphenylene, coumarin, porphyrin, diazaporphyrin, pyrrole methylene, and benzotriazole.

[0057] In addition, the adhesive resin of the light-absorbing layer 20 fixes the organic light absorber and prevents it from being exposed to moisture or oxygen, thereby improving the stability of the organic light absorber dispersed within the light-absorbing layer 20. Preferably, the adhesive resin of the light-absorbing layer 20 as described above includes at least one resin selected from esters, olefins, acrylics, ethers, urethanes, carbonates, silicones, and epoxy resins.

[0058] In one embodiment, the light-absorbing layer 20 comprises 0.1 to 40 parts by weight of an organic light absorber, more preferably 0.5 to 40 parts by weight, relative to 100 parts by weight of the adhesive resin. This is because when the organic light absorber is less than 0.1 parts by weight, the blocking efficiency of the light-absorbing layer 20 for short-wavelength blue light decreases, failing to prevent the degradation of the organic phosphor in the wavelength conversion layer 10. When the organic light absorber exceeds 40 parts by weight, the blocking efficiency of the light-absorbing layer 20 for short-wavelength blue light cannot be further improved, only increasing manufacturing costs. Furthermore, the light transmission efficiency of the light-absorbing layer 20 decreases, thereby reducing the luminous efficiency of the organic phosphor in the wavelength conversion layer 10.

[0059] In addition, the light-absorbing layer 20 may also include at least one selected from UV absorbers, UV stabilizers, and antioxidants. Regarding the UV absorbers and UV stabilizers, when the color conversion sheet 100 is stored externally, they function to prevent the organic light absorbers of the light-absorbing layer 20 and the organic phosphors of the wavelength conversion layer 10 from deterioration due to UV radiation from natural light. Regarding the antioxidants, they eliminate free radicals that may be generated during the deterioration of the organic light absorbers in the light-absorbing layer 20 during light absorption, thereby preventing the chain-like deterioration of other organic light absorbers based on free radicals.

[0060] In one embodiment, the wavelength conversion layer 10 is located on one surface of the light-absorbing layer 20 and includes an organic phosphor dispersed in a resin matrix.

[0061] The resin matrix of the wavelength conversion layer 10 immobilizes the organic phosphor and prevents it from being exposed to moisture or oxygen, thereby preventing the degradation of the organic phosphor dispersed in the resin matrix. Preferably, the resin matrix of the wavelength conversion layer 10 as described above includes at least one selected from ester, olefin, acrylic, ether, urethane, carbonate, and imide resins.

[0062] In addition, the resin contained in the resin matrix can have a number-average molecular weight (Mn) of 1000~50000 g / mol or a weight-average molecular weight (Mw) of 50000~2000000 g / mol. This is because when the number-average molecular weight of the resin contained in the resin matrix is ​​less than 1000 g / mol or the weight-average molecular weight is less than 50000 g / mol, it is difficult to fix the organic phosphor. This may lead to temperature-induced aggregation of the organic phosphor and the degradation of its optical properties caused by aggregation. When the number-average molecular weight exceeds 50000 g / mol or the weight-average molecular weight exceeds 2000000 g / mol, the solubility of the resin matrix in the solvent is poor, making it difficult to form the wavelength conversion layer 20.

[0063] Furthermore, the acid value of the resin contained in the resin matrix can be 0-15 mg KOH / g, preferably 0-10 mg KOH / g, and the hydroxyl value can be 0-30 mg KOH / g, preferably 0-20 mg KOH / g, more preferably 0-10 mg KOH / g. Typically, resin matrices used as the wavelength conversion layer of a color conversion sheet include esters, olefins, acrylics, ethers, urethanes, carbonates, and imides. Since functional groups such as hydroxyl or carboxylic acid groups present in these resins accelerate the deterioration of the organic phosphor dispersed in the resin matrix, thereby reducing the reliability of the organic phosphor, it is preferable to maintain the acid value and hydroxyl value within the aforementioned ranges.

[0064] More specifically, the resin matrix constituting the wavelength conversion layer 10 may include at least one of polyester, modified polyester, polyethylene, polycyclo-olefin, poly(methyl)methacrylate, polyethylene glycol, polyurethane, polycarbonate, and polyimide, or in the form of block copolymers thereof.

[0065] Furthermore, the glass transition temperature (Tg) of the resin matrix of the wavelength conversion layer 10 is preferably 50°C to 150°C, more preferably 60°C to 140°C, and even more preferably 70°C to 140°C. This is because when the glass transition temperature of the resin matrix is ​​below 50°C, aggregation of multiple organic phosphors occurs over time in high-temperature or high-temperature and high-humidity environments, resulting in a decrease in optical properties. When the glass transition temperature exceeds 150°C, the high crystallinity of the resin may lead to poor solubility in the solvent, and when the film is dried after being coated onto the base film, film curling may occur due to resin crystallization.

[0066] Furthermore, the organic phosphor dispersed in the resin matrix of the wavelength conversion layer 10 is a phosphor that emits light with a wavelength different from that of the excitation light when irradiated by excitation light. Depending on the purpose, the wavelength conversion layer 10 may include one or more of green phosphors or red phosphors, or a combination thereof may be used to emit light of multiple colors.

[0067] In a wavelength conversion layer 10, the organic phosphor may include multiple organic phosphors that emit the same color. These multiple organic phosphors may be made of the same material or different materials. For example, the wavelength conversion layer 10 may emit only one color of light by including only one type of organic phosphor, either green or red. Alternatively, when using only one color of organic phosphor in a wavelength conversion layer, two or more wavelength conversion layers may be formed separately, each including organic phosphors of different colors, to emit multiple colors of light.

[0068] Such organophosphors may include: compounds or their derivatives having fused aromatic rings such as naphthalene, anthracene, phenanthrene, pyrene, thionylene, triphenylene, perylene, fluoranthene, fluorene, indene, etc. (e.g., 2-(benzothiazol-2-yl)-9,10-diphenylanthracene or 5,6,11,12-tetraphenylnaphthonaphthylene, etc.); compounds or their derivatives having heteroaromatic rings such as furan, pyrrole, thiophene, thiophene, 9-siliconylene, 9,9'-spirobiscillafluorene, benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthrene, pyridine, pyrazine, naphthidine, quinoxaline, pyrrolopyridine, and thioxanthium; borane derivatives; stilbene derivatives; aminostyryl derivatives, such as 4,4'-bis(2- (4-Diphenylaminophenyl)vinyl)biphenyl, 4,4'-bis(N-(stilbene-4-yl)-N-phenylamino)stilbene, etc.; aromatic acetylene derivatives; tetraphenylbutadiene derivatives; stilbene derivatives; aldehyde azo derivatives; pyrrole methylene derivatives; coumarin derivatives, such as diketopyrrolo[3,4-c]pyrrole derivatives, 2,3,5,6-1H,4H-tetrahydro-9-(2'-benzothiazolyl)quinolino[9,9a,1-gh]coumarin, etc.; azole derivatives and their metal complexes, such as imidazole, thiazole, thiadiazole, carbazole, oxazole, dioxazole, trioxazole, etc.; and aromatic amine derivatives represented by N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine.

[0069] An embodiment of the present invention provides an organic phosphor (green organic phosphor) that absorbs blue light and emits green light, and may contain a compound represented by the following chemical formula 1.

[0070] (Chemical Formula 1)

[0071] Additionally, the wavelength conversion layer 10 may include a red organic phosphor dispersed in a resin matrix. The red organic phosphor dispersed in the resin matrix of the wavelength conversion layer can absorb blue or green light and emit red light, and the red organic phosphor may include a compound represented by the following chemical formula 2.

[0072] (Chemical Formula 2)

[0073] Relative to the resin solids content of 100 parts by weight of the resin matrix, the aforementioned organic phosphor (green organic phosphor and / or red organic phosphor) preferably comprises 0.0001 to 10 parts by weight. This is because when the organic phosphor is contained in less than 0.0001 parts by weight, the color conversion effect to the desired color by the color conversion sheet 100 may be negligible, and when it exceeds 10 parts by weight, quenching may occur due to the aggregation and other interactions of the organic phosphor.

[0074] Furthermore, the thickness of the wavelength conversion layer 10, which contains the organic phosphor dispersed in the resin matrix, is preferably from 1 μm to 150 μm, more preferably from 1 μm to 100 μm, and even more preferably from 1 μm to 50 μm. This is because when the thickness of the wavelength conversion layer 10 exceeds 150 μm, it is difficult to sufficiently remove the solvent, which may cause the organic phosphor to deteriorate due to the various solvents remaining in the wavelength conversion layer 10. When the thickness is less than 1 μm, it cannot perform the function of the wavelength conversion layer.

[0075] In a color conversion sheet according to an embodiment of the present invention, preferably, the light-absorbing layer 20 is located in the direction in which light irradiates the wavelength conversion layer 10. That is, preferably, the light-absorbing layer 20 is located on a surface of the wavelength conversion layer 10 close to the light source. This is because the light-absorbing layer 20 is located in the direction of light irradiation, thus blocking short-wavelength blue light in the blue light irradiated from the light source to the wavelength conversion layer 10 in advance, thereby more effectively preventing the degradation of the organic phosphor in the wavelength conversion layer 10.

[0076] Additionally, if necessary, at least one surface in contact with the outside of the wavelength conversion layer 10 and the light-absorbing layer 20 may further include a substrate layer 30, 40. Figure 1 In the color conversion layer 100 shown, the first substrate layer 30 is located on the surface opposite to the surface of the light-absorbing layer 20 formed by the wavelength conversion layer 10, i.e., the outer surface of the wavelength conversion layer 10, and the second substrate layer 40 is located on the surface of the light-absorbing layer 20. As described above, in Figure 1 In the color conversion layer 100, the first substrate layer 30 and the second substrate layer 40 are located outside the wavelength conversion layer 10 and the light absorption layer 20, which can protect the wavelength conversion layer 10 and the light absorption layer 20 from the outside.

[0077] The first substrate layer 30 and the second substrate layer 40 can be transparent and flexible polymer films, such as polyethylene terephthalate, polyethylene naphtalate, polyacrylate, polycarbonate, polyetherimide, and polyimide, but not limited to these, and a variety of polymer films can be used.

[0078] The first substrate layer 30 and the second substrate layer 40 can be diffusion films (sheets), prism sheets, etc., but are not limited to these, and can be sheets with multiple functions.

[0079] With this configuration, after 100 hours at 60°C, the change in the luminance L value of the color conversion sheet in one embodiment of the present invention can be less than 1%. When the change in luminance L value is greater than 1%, the degradation of the organic phosphor becomes obvious over time, and the reliability of the color conversion sheet decreases.

[0080] Then, refer to Figure 2 This is a cross-sectional view of a color conversion sheet according to another embodiment of the present invention. The color conversion sheet of another embodiment of the present invention will be described, and details will be omitted. Figure 1 A description of repetitive structures.

[0081] Reference Figure 2 , Figure 2 The color conversion sheet 200 of another embodiment of the present invention shown may have a second base layer 40 formed between the wavelength conversion layer 10 and the light absorption layer 20. If necessary, a first base layer 30 may be formed on the outer surface of the wavelength conversion layer 10.

[0082] As mentioned above, in Figure 2 In another embodiment of the present invention, the color conversion sheet 200, the first substrate layer 30 and the second substrate layer 40 can be directly disposed on both sides of the wavelength conversion layer 10, which can protect the organic phosphor contained in the wavelength conversion layer 10 from external moisture or air. If necessary, back coating particles can be mixed in the first substrate layer 30 and the second substrate layer 40 to serve as a back coating.

[0083] Then, refer to Figure 3 This is a schematic diagram of a backlight unit including a color conversion sheet according to an embodiment of the present invention. The backlight unit including a color conversion sheet according to an embodiment of the present invention will be described.

[0084] refer to Figure 3An embodiment of the present invention includes a backlight unit 900 comprising a color conversion sheet, which may include: a light source 700; a reflector 500, which can improve light efficiency by reflecting light emitted from the light source 700; a light guide plate 300, located above the reflector 500 and used to uniformly propagate light emitted from the light source 700; and a color conversion sheet 100, located above the light guide plate 300. The color conversion sheet can be applied to... Figure 1 or Figure 2 The color conversion sheet shown.

[0085] Preferably, in the color conversion layer 100, the light-absorbing layer 20 is located in the wavelength conversion layer 10 in the direction close to the light source 700, that is, the direction in which light is incident from the light source 700. This can block the short-wavelength blue light in the blue light that is irradiated to the wavelength conversion layer 10 in advance, thereby more effectively preventing the deterioration of the organic phosphor in the wavelength conversion layer 10.

[0086] Preferably, Figure 3 The light source 700 shown includes at least one light source selected from edge-type light sources, side-chain type light sources and direct-lit light sources, but is not limited to this, and a variety of light sources can be used.

[0087] In addition, the upper part (surface) of the color conversion sheet 100 may include at least one optical sheet, such as a diffuser sheet, a prism sheet, and a dual brightness enhancement film (DBEF).

[0088] The structure and effects of the present invention will now be described in more detail through embodiments and comparative examples. However, the following embodiments are provided to further illustrate the present invention and are not intended to limit the scope of the invention.

[0089] [Example] [Example 1] Step 1: Formation of the wavelength conversion layer After dissolving the green organic phosphor according to the above chemical formula 1 in methyl ethyl ketone (MEK) to prepare an organic phosphor solution, the organic phosphor solution was mixed with polyester resin. The polyester resin was prepared by dissolving polyester chips (SK Chemicals, Es-120) with an acid value of less than 3 mg KOH / g and a hydroxyl value of 2-6 mg KOH / g in MEK, and then adding MEK to achieve a viscosity of 150 cps. The mixture was then stirred at 150 rpm for 30 minutes to prepare the wavelength conversion layer composition. At this point, based on a polyester solids content of 100 parts by weight, the green organic phosphor reached 0.4 parts by weight. Next, the wavelength conversion layer composition was applied to the opposite side of the diffusion layer of a diffusion film (TAK Corporation, TDF12C), and then dried at 120°C for 2 minutes to form a wavelength conversion layer with a thickness of 15 μm.

[0090] Step 2: Formation of the light-absorbing layer Next, for the silicone resin (DOW, DC7663), 50 parts by weight of toluene were added, and the mixture was stirred at 150 rpm for 2 hours. Then, 0.5 parts by weight of platinum catalyst (DOW, SYL-OFF 4000 catalyst (CATALYST)) were added and stirred for an additional 30 minutes. Based on a silicone resin solids content of 100 parts by weight, 40 parts by weight of a coumarin compound (MERCK, Courmarin 102) were added, and the mixture was stirred at 150 rpm for 30 minutes to prepare the light-absorbing layer composition. Next, the light-absorbing layer composition was rod-coated onto the top of a polyethylene terephthalate film (TAK, PH8) and then dried at 170°C for 1 minute to form a light-absorbing layer with a thickness of 10 μm.

[0091] Step 3: Preparation of the color conversion film After the light-absorbing layer formed in step 2 and the wavelength conversion layer formed in step 1 are stacked together in contact with each other, a color conversion sheet is prepared using a roller laminator (GMP, EXCELAM Ⅱ-355Q).

[0092] [Example 2] The difference is that, based on 100 parts by weight of silicone resin solids, 20 parts by weight of benzotriazole compound (BASF, Tinuvin 970) was added as an organic light absorber. Otherwise, the color conversion sheet was prepared using the same method as in Example 1.

[0093] [Example 3] The difference is that, based on 100 parts by weight of silicone resin solids content, 0.3 parts by weight of a porphyrin compound (YAMADA Chemical, FDB-002) was added as an organic absorber, and based on 100 parts by weight of silicone resin solids content, 1 part by weight of an organic absorber (TOYO INK, NUV-240) was added. Otherwise, the color conversion sheet was prepared using the same method as in Example 1.

[0094] [Example 4] The difference is that the light-absorbing layer composition uses a polyester resin in which polyester (TOYOBO, Vylon 630) is dissolved in methyl ethyl ketone. Otherwise, the color conversion sheet was prepared in the same manner as in Example 1.

[0095] [Example 5] The difference is that, based on a silicone resin solid content of 100 parts by weight, 0.1 parts by weight of a porphyrin compound (YAMADA Chemical, FDB-002) was added as an organic light absorber. Otherwise, the color conversion sheet was prepared using the same method as in Example 1.

[0096] [Comparative Example] [Comparative Example 1] The difference is that the process of forming the light-absorbing layer is omitted, and the polyethylene terephthalate film (TAK, PH8) is directly laminated on the wavelength conversion layer. Otherwise, the color conversion sheet is prepared in the same way as in Example 1.

[0097] [Comparative Example 2] The difference is that, based on 100 parts by weight of silicone resin solids, 0.01 parts by weight of porphyrin compound (YAMADA Chemical, FDB-002) was added as an organic light absorber. Otherwise, the color conversion sheet was prepared using the same method as in Example 1.

[0098] [Comparative Example 3] The difference is that, based on a silicone resin solid content of 100 parts by weight, 50 parts by weight of a coumarin-based organic light absorber (MERCK, Courmarin 102) was added. Otherwise, the color conversion sheet was prepared using the same method as in Example 1.

[0099] [Comparative Example 4] The difference is that, based on 100 parts by weight of silicone resin solids, 10 parts by weight of a coumarin compound (MERCK, Courmarin 153) was added as an organic light absorber, and 35 parts by weight of a benzotriazole compound (BASF, Tinuvin 970) was added based on 100 parts by weight of silicone resin solids. Otherwise, the color conversion sheet was prepared using the same method as in Example 1.

[0100] Using the color conversion sheets according to Examples 1 to 5 and Comparative Examples 1 to 4, the physical properties were measured through the following experimental examples, and the results are shown in Tables 1 to 3 below.

[0101] [Experimental Example] (1) Measurement of transmittance In the color conversion films of Examples 1 to 5 and Comparative Examples 2 to 4, the transmittance of the absorber layer was measured using a spectrophotometer (Shimadzu Corporation, MPC-3100) before the wavelength conversion layer was laminated. The transmittance measured in the wavelength regions of 410 nm, 430 nm, and 460 nm is shown in Table 1.

[0102] In addition, in Comparative Example 1, the transmittance of the polyethylene terephthalate film itself was measured by the same method before the wavelength conversion layer was laminated on the polyethylene terephthalate film and is shown in Table 1.

[0103] Next, using the transmittance (transmittance of the polyethylene terephthalate film) measured in Comparative Example 1 as a 100% baseline, the relative proportion of the measured transmittance of the polyethylene terephthalate film and the light-absorbing layer stacked together was calculated and recorded in Table 1 as the transmittance of the light-absorbing layer.

[0104] (2) Measurement of blue light spectrum changes (luminescence intensity) In the color conversion sheets of the embodiments and comparative examples, before the light-absorbing layer was stacked on the wavelength conversion layer, the blue light spectrum change in the light-absorbing layer was measured using a spectroradiometer (KONICA MINOLTA, CA-S20W). At this time, the color conversion sheet was used to stack a light-absorbing layer coated on a polyethylene terephthalate film on the upper surface of the backlight plate of a blue LED with a maximum emission peak at a wavelength of 447 nm and a full width at half maximum (FWHM) of 18 nm, and after additionally stacking prism sheets on the upper surface of the light-absorbing layer.

[0105] Therefore, the luminescence intensity at the maximum emission peak of the incident light (B1), the luminescence intensity at the maximum emission peak of the transmitted light (T1), the luminescence intensity of the transmitted light at a wavelength of 438 nm (short wavelength) corresponding to half the maximum luminescence intensity of the incident light (TS1), and the luminescence intensity of the transmitted light at a wavelength of 456 nm (long wavelength) corresponding to another half the maximum luminescence intensity of the incident light (TS2) were measured.

[0106] (3) Measurement of changes in luminance and chromaticity coordinates For the color conversion sheets in the embodiments and comparative examples, after measuring the initial luminance (L) and chromaticity coordinates (x, y) values, the chromaticity coordinate changes (Δx, Δy) and luminance changes (ΔLv) were measured after 100 hours using a spectroradiometer (KONICA MINOLTA, CA-S20W) at a temperature of 60°C. At this time, the experiment was conducted after the color conversion sheet was stacked on the upper surface of the light guide plate of the backlight unit, which includes a 447nm wavelength blue LED and a light guide plate, and after an additional prism sheet was stacked on the upper surface of the color conversion sheet.

[0107] Table 1 shows the transmittance measurement results of the light-absorbing layer in the examples and comparative examples.

[0108] Table 1

[0109] In the transmittance values ​​listed in Table 1 above, the values ​​in parentheses are based on the transmittance of the PET film (the transmittance of Comparative Example 1) and represent the transmittance of the light-absorbing layer calculated by calculating the relative ratio of the transmittance measured based on this reference. As shown in Table 1 above, the transmittance of the light-absorbing layer was evaluated when coated on a PET film with a thickness of 100 μm. Therefore, when comparing the transmittance of the PET film in each wavelength region as 100%, it can be seen that the following conditions are met: Examples 1 to 5 block more than 60% of the wavelength region below 410 nm, block more than 10% of the wavelength region below 430 nm, and transmit more than 80% of the wavelength region above 460 nm.

[0110] Conversely, it can be confirmed that the content of the organic light absorber in Comparative Example 2 is too low, so the blocking efficiency at 410 nm and 430 nm is very low. In addition, it can be confirmed that even though the content of the organic light absorber in Comparative Example 3 is increased compared with Example 1, the increase in blocking efficiency at 410 nm and 430 nm is not significant.

[0111] Furthermore, it can be confirmed that Comparative Example 4 blocks more than 60% of the wavelength region below 410nm and more than 10% of the wavelength region below 430nm, but the transmittance in the wavelength region of 460nm is very low.

[0112] Table 2 shows the blue light spectrum measurement results of the light-absorbing layers of the examples and comparative examples.

[0113] Table 2

[0114] As shown in Table 2, it can be seen that Examples 1 to 5 all satisfy Equations 1 and 2. The results show that the long-wavelength blue light region after 440nm required for the organic phosphor of wavelength conversion layer 10 to emit light is not absorbed in large quantities, while the short-wavelength blue light is selectively blocked in large quantities.

[0115] Conversely, the value of Equation 2 in Comparative Example 2 is close to 1.0, thus confirming that it does not have a short-wavelength blue light blocking effect. Although Comparative Example 3 satisfies both Equations 1 and 2, compared with Example 1, as the content of organic light absorber increases, the short-wavelength blue light blocking effect is hardly improved. Moreover, it can be confirmed that due to the excessive increase in content, problems such as the organic light absorber precipitating onto the surface of the light-absorbing layer and the resulting increase in surface haze are generated, and problems such as the decrease in brightness of the wavelength conversion layer are generated.

[0116] In addition, the value of Equation 1 in Comparative Example 4 is less than 0.6, which not only absorbs the short-wavelength blue light region, but also the long-wavelength blue light region after 440 nm required for the organic phosphor of wavelength conversion layer 10 to emit light, thereby reducing the luminous efficiency of the organic phosphor.

[0117] Table 3 shows the results of the measurement of luminance and color coordinate changes in the examples and comparative examples.

[0118] Table 3

[0119] As shown in Table 3, the light-absorbing layers in Examples 1 to 5 all satisfy Equations 1 and 2. The results show that even after processing at 60°C for 100 hours, the changes in the chromatic coordinates of the x-axis and y-axis are within ±0.005.

[0120] Conversely, it can be confirmed that Comparative Example 1, which did not form a light-absorbing layer, had the largest x-axis change value of -0.002 and y-axis change value of -0.010 among all embodiments and comparative examples.

[0121] Furthermore, it can be confirmed that, compared with Examples 1 to 5, the color coordinate change of Comparative Example 2, which does not satisfy Formula 2, is more significant. Although Comparative Example 3 satisfies Formulas 1 and 2, compared with Example 1, the improvement effect on color coordinate change is very small as the content of organic absorber increases. In addition, it can be confirmed that Comparative Example 4 does not satisfy Formula 1, thus the luminous efficiency of the organic phosphor is reduced, and the color coordinate change is relatively more significant compared with Examples 1 to 5.

[0122] As described above, it can be confirmed that compared with Examples 1 to 5, in which the light-absorbing layers all satisfy Equations 1 and 2, the color coordinate changes of the comparative examples, in which the light-absorbing layers do not satisfy Equations 1 and / or 2, are more obvious.

[0123] Furthermore, it can be confirmed that after processing at 60°C for 100 hours, the brightness change in Examples 1 to 5 was less than 1%, while Comparative Example 1, which did not form a light-absorbing layer, showed a decrease in brightness, with a brightness change of 4.8% even after 100 hours of processing. Comparative Example 2, whose light-absorbing layer did not satisfy Formula 2, also showed a decrease in brightness, with a brightness change of 4.1% after 100 hours of processing. Although Comparative Example 3 satisfied Formulas 1 and 2, compared with Example 1, it can be confirmed that the improvement effect on brightness change was very small as the content of organic light absorber increased.

[0124] As described above, in the case of the color conversion sheet without a light-absorbing layer as shown in Comparative Example 1 and in the case of the case where Equation 2 is not satisfied as shown in Comparative Example 2, it can be confirmed that significant color and brightness changes occur under high-temperature conditions. Conversely, in the case where the light-absorbing layer satisfies Equations 1 and 2, it can be confirmed that even under high-temperature conditions, the color coordinate changes and brightness changes are very small.

[0125] As described above, the color conversion sheet of the present invention additionally forms a light-absorbing layer to prevent degradation based on organic phosphor light, thereby selectively blocking short-wavelength blue light and transmitting long-wavelength blue light, thus preventing degradation of the organic phosphor and preventing a decrease in luminous efficiency. Therefore, it has the technical effect of solving the problems of changes in brightness characteristics and color caused by degradation of the organic phosphor and changes in luminous efficiency.

[0126] While the invention has been specifically shown and described with reference to exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the foregoing claims.

Claims

1. A color conversion chip, characterized in that, include: Wavelength conversion layer, organic phosphor dispersed in resin matrix, and A light-absorbing layer is located on one surface of the wavelength conversion layer, and the organic light absorber is dispersed within the adhesive resin; The light-absorbing layer blocks more than 60% of wavelengths below 410nm, more than 10% of wavelengths above 430nm, and transmits more than 80% of wavelengths above 460nm.

2. The color conversion sheet according to claim 1, characterized in that, The light-absorbing layer has a maximum emission peak in the wavelength range of 440nm to 470nm. When single-mode light with a full width at half maximum (FWHM) of less than 40nm is incident, the light transmitted from the color conversion sheet satisfies the following equation: (Equation 1) T1 / B1≥0.6 B1: Luminous intensity at the maximum emission peak of the incident light. T1: Luminous intensity at the maximum emission peak of transmitted light.

3. The color conversion sheet according to claim 1, characterized in that, The light-absorbing layer has a maximum emission peak in the wavelength range of 440nm to 470nm. When single-mode light with a full width at half maximum (FWHM) of less than 40nm is incident, the light transmitted from the color conversion sheet satisfies the following equation 2: (Equation 2) TS1 / TS2≤0.9 TS1: The luminous intensity of transmitted light at the position with the relatively shorter wavelength among the two positions where the incident light reaches half its maximum luminous intensity. TS2: The luminous intensity of transmitted light at the position with the relatively longer wavelength between the two positions where the incident light reaches half its maximum luminous intensity.

4. The color conversion sheet according to claim 1, characterized in that, The organic light absorber includes at least one selected from anthracene, tetraphenylene, coumarins, porphyrins, diazaporphyrins, pyrrole methylenes, and benzotriazoles.

5. The color conversion sheet according to claim 1, characterized in that, The adhesive resin of the light-absorbing layer includes at least one resin selected from esters, olefins, acrylics, ethers, carbamates, carbonates, silicones, and epoxy resins.

6. The color conversion sheet according to claim 1, characterized in that, The light-absorbing layer comprises 0.1 to 40 parts by weight of the organic light absorber relative to 100 parts by weight of the adhesive resin.

7. The color conversion sheet according to claim 1, characterized in that, The light-absorbing layer also includes at least one selected from UV absorbers, UV stabilizers, and antioxidants.

8. The color conversion sheet according to claim 1, characterized in that, The organic phosphor includes at least one of green organic phosphors and red organic phosphors.

9. The color conversion sheet according to claim 1, characterized in that, The resin matrix of the wavelength conversion layer includes at least one resin selected from esters, olefins, acrylics, ethers, carbamates, carbonates, and imides.

10. The color conversion sheet according to claim 1, characterized in that, The wavelength conversion layer comprises 0.0001 to 10 parts by weight of the organic phosphor, relative to 100 parts by weight of the resin matrix.

11. The color conversion sheet according to claim 1, characterized in that, The resin matrix of the wavelength conversion layer has a glass transition temperature of 50°C to 150°C.

12. The color conversion sheet according to claim 1, characterized in that, At a temperature of 60°C, after 100 hours, the change in the luminance L value of the color conversion sheet is less than 1%.

13. The color conversion sheet according to claim 1, characterized in that, The light-absorbing layer is located in the direction in which light irradiates the wavelength conversion layer.

14. The color conversion sheet according to claim 1, characterized in that, The color conversion chip also includes: A polyester first substrate layer located on the other surface of the wavelength conversion layer.

15. The color conversion sheet according to claim 14, characterized in that, The color conversion chip also includes: A second polyester substrate layer located between the wavelength conversion layer and the light-absorbing layer or on the surface of the light-absorbing layer.

16. A backlight unit, characterized in that, Includes the color conversion sheet according to claim 1.

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