Glass composition, and color conversion glass comprising same

Abstract

The present invention relates to a glass composition and a color conversion glass comprising same. The glass composition for a color conversion glass according to an embodiment of the present invention comprises 45-65 mol% of SiO2, 3-10 mol% of BaO, and 10-30 mol% of ZnO, and does not comprise B2O3.

Description

Glass composition and color-changing glass comprising the same

[0001] The present invention relates to a glass composition and a color-conversion glass comprising the same.

[0002] A light-emitting diode (LED) is a semiconductor made of materials such as gallium (Ga), phosphorus (P), and arsenic (As), and has the property of emitting light when current flows through it. Compared to conventional light bulbs, LEDs have a longer lifespan, a faster response speed, and can be miniaturized while emitting brightly colored light, so they are widely used as a light source for various display devices. For example, LED packages containing LED chips are used as light-emitting elements in backlight units (BLUs) that emit light from behind the LCD screen of liquid crystal displays (LCDs), and LED packages are also used for vehicle lighting.

[0003] Typically, an LED package is formed by mounting an LED chip on a lead frame, encapsulating it with a sealant, and then attaching a lens. The sealant's primary function is to protect the LED chip from external impacts while transmitting and emitting light from the chip to the outside. Additionally, a phosphor can be placed along the path of light emitted from the LED chip to change the color of the light emitted from the LED chip.

[0004] These encapsulating materials are known to use epoxy and silicone resins, and to use fluorescent materials separately or mixed with the encapsulating materials. However, encapsulating materials made of resin can deteriorate due to the rapid temperature rise of the LED chip resulting from high output, which can lead to a decrease in luminous efficiency.

[0005] Recognizing this problem, technology has recently been developed to perform color conversion using phosphor-in-glass (PIG), also known as color-conversion glass. Color-conversion glass offers the advantage of thermal and chemical stability because the phosphor is encapsulated within the glass.

[0006] Color-converting glass can be manufactured from a B2O3-SiO2-ZnO series glass composition to match the refractive index of the fluorescent material. However, glass compositions containing B2O3 have been found to have poor chemical durability, resulting in relatively low stability.

[0007] [Prior Art Literature]

[0008] [Patent Document]

[0009] (Patent Document 1) Patent Registration No. 10-2215135 (February 4, 2021)

[0010] The present invention is intended to solve the problems of the prior art described above, and has the purpose of providing a glass composition and a color conversion glass including the same, which increases the luminous efficiency of an LED package by making the refractive index of the glass similar to the refractive index of a fluorescent material, while also improving stability.

[0011] A glass composition for color conversion glass according to one embodiment of the present invention comprises 45 to 65 mol% of SiO2, 3 to 10 mol% of BaO, and 10 to 30 mol% of ZnO, and does not contain B2O3.

[0012] A glass composition for color conversion glass according to one embodiment of the present invention may further include at least one of 3 to 8 mol% of La2O3 and ZrO2.

[0013] A glass composition for color conversion glass according to one embodiment of the present invention may further include 8 mol% or less of an alkali metal oxide.

[0014] A glass composition for color conversion glass according to one embodiment of the present invention may further include 5 mol% or less of MgO.

[0015] A color conversion glass according to one embodiment of the present invention can be manufactured by including the glass composition and a fluorescent substance.

[0016] According to one embodiment of the present invention, the light efficiency and stability of the LED package can be improved by the glass composition not including B2O3. Furthermore, according to one embodiment of the present invention, high refractive index characteristics can be achieved by including BaO, ZrO2, La2O3, etc.

[0017] Figure 1 is a drawing schematically showing a cross-section of an LED package.

[0018] [Explanation of symbols]

[0019] 10: LED package

[0020] 11: LED chip

[0021] 12: Color-changing glass

[0022] Hereinafter, with reference to the attached drawings, a preferred embodiment of the present invention will be described in detail to a degree that a person having ordinary skill in the art to which the present invention pertains can easily practice the present invention.

[0023] In order to clearly explain the present invention, the description of parts unrelated to the present invention is omitted, and the same reference numerals are used for the same components throughout the specification.

[0024] The detailed description set forth below is not intended to be limiting, and the scope of the present invention should be taken to encompass the scope claimed in the claims and all scopes equivalent thereto.

[0025] Figure 1 is a drawing schematically showing a cross-section of an LED package.

[0026] Referring to FIG. 1, an LED package includes an LED chip (11) and a color conversion glass (12). The color conversion glass (12) according to one embodiment of the present invention contains a fluorescent substance within the glass and can be used to convert the color of light emitted from the LED chip (11) into another color. For example, the color conversion glass (12) is disposed on one side of the LED chip (11) and can convert the color (e.g., blue) of light emitted from the LED chip (11) into another color (e.g., white) depending on the fluorescent substance contained therein.

[0027] Color conversion glass (12) includes glass forming a basic structure and a fluorescent substance distributed in the glass that converts the color of light. According to the present embodiment, the color conversion glass (12) has a unique glass composition that has high refractive index characteristics while also being stable.

[0028] Meanwhile, although FIG. 1 illustrates an LED package (10) comprising one layer each of an LED chip (11) and a color conversion glass (12), the present invention is not limited thereto. That is, the LED package may be implemented in such a way that the LED chip and the color conversion glass are each comprised of multiple layers or in a different form, and it should be understood that the present invention is not limited to a specific form of the LED package.

[0029] A color-conversion glass (12) according to one embodiment of the present invention can be manufactured by firing a mixture of a glass composition and a fluorescent agent. Below, the role and preferred content of each component of the glass composition will be described. Here, the content of each component is based on the total content of the glass composition.

[0030] The glass composition of the color conversion glass (12) according to one embodiment of the present invention includes SiO2, BaO and ZnO.

[0031] In a glass composition according to one embodiment of the present invention, SiO2 is a component that contributes to improving the stability of the glass by forming a network structure, and in this embodiment, the content of SiO2 is 45 mol% to 65 mol%. If the content of SiO2 is too low than 45 mol%, the stability of the glass may be reduced, and if the content of SiO2 is greater than 65 mol%, the softening temperature of the glass may become excessively high. If the softening temperature of the glass becomes high, the fluorescent agent may deteriorate during the firing process of the mixture of the glass composition and the fluorescent agent for the manufacture of color conversion glass, which may cause a problem of reduced fluorescent properties.

[0032] In a glass composition according to one embodiment of the present invention, ZnO functions to break the bonds of SiO2, thereby lowering the softening temperature, improving the melting property of the glass, and enhancing the refractive index of the glass. To this end, the content of ZnO in the present embodiment is set to 10 mol% to 30 mol%. If the content of ZnO is less than 10 mol%, the melting property of the glass may be low, making glass manufacturing difficult, and if the content of ZnO is greater than 30 mol%, crystals may form inside the glass, lowering the transparency of the color conversion glass.

[0033] In a glass composition according to one embodiment of the present invention, BaO functions to increase the refractive index of the color conversion glass, and in this embodiment, the content of BaO is set to 3 mol% to 10 mol%. If the content of BaO is greater than 10 mol%, the transition temperature of the glass may increase or devitrification may occur, and the melting property of the glass may decrease, resulting in the production of an inhomogeneous melt.

[0034] A glass composition according to one embodiment of the present invention may further include at least one of La2O3 and ZrO2 to increase the refractive index of the glass. In this embodiment, the content of La2O3 and / or ZrO2 is 3 mol% to 8 mol%. If the content of La2O3 and / or ZrO2 is greater than 8 mol%, the transition temperature of the glass may increase or devitrification may occur, and the melting property of the glass may decrease, resulting in the generation of a non-homogeneous melt.

[0035] According to one embodiment of the present invention, in order to obtain a stable glass having a refractive index of 1.6 or more, the glass composition may contain a sum of BaO, La2O3, and ZrO2 of 8 mol% or more.

[0036] A glass composition according to one embodiment of the present invention may further include an alkali metal oxide. In one embodiment, the alkali metal oxide may include at least one of Li2O and Na2O. The alkali metal oxide may perform the function of breaking the bond between silicon atoms (Si) and oxygen atoms (O) in SiO2, thereby improving melting property and lowering the glass transition temperature. However, since the alkali metal oxide has high reactivity, if added in an excessively high content, it may react with a phosphor during the manufacturing process of the color conversion glass, thereby deteriorating the properties of the phosphor and reducing the luminous efficiency. Considering this point, the glass composition according to the present embodiment may contain an alkali metal oxide in an amount of 8 mol% or less.

[0037] A glass composition according to one embodiment of the present invention may further include MgO as a network-modifying oxide to improve the meltability of the glass. MgO can lower the firing temperature of the color-conversion glass, thereby improving the meltability of the glass. However, since the transmittance of the glass may decrease when the MgO content increases, the MgO content may be set to 5 mol% or less in consideration of this point.

[0038] According to one embodiment of the present invention, the glass composition of the color conversion glass (12) does not include B2O3. In the glass composition of conventional color conversion glass, B2O3 has been used to lower the firing temperature of the glass due to its low melting point. However, since B2O3 has poor chemical durability, it is generally not used alone but mixed with SiO2 or other components. Nevertheless, glass manufactured including B2O3 has lower stability compared to SiO2 glass, which may adversely affect the overall physical properties of the glass.

[0039] In one embodiment of the present invention, the glass composition does not contain B2O3, so that it can exhibit excellent refractive index as described above while also improving stability compared to the prior art.

[0040] According to one embodiment of the present invention, the transition temperature (Tg) of the glass composition including the above-described materials may be 550 to 600°C. The firing temperature for sintering the glass composition is suitably about 100°C higher than the transition temperature, and preferably 650 to 750°C. If the firing temperature is low, the firing temperature is lower than the softening behavior temperature, so that the firing is not performed properly, and thus a large number of bubbles may be generated in the glass, which may reduce the light transmittance. Conversely, if the firing temperature is excessively high, the phosphor may deteriorate, which may reduce its characteristics.

[0041] According to one embodiment of the present invention, the refractive index of the color conversion glass manufactured with the content ratio of the above-described compositions is 1.6 to 1.7. Therefore, compared to conventional color conversion glass, the difference in the refractive index of the glass and the fluorescent material is minimized, so that scattering, etc. can be suppressed when light passes through the color conversion glass, and as a result, high light efficiency can be implemented. In addition, according to one embodiment of the present invention, by intentionally excluding alkali metal oxides from the glass composition, the phenomenon of deterioration of the characteristics of the fluorescent material and the phenomenon of devitrification of the glass can be minimized, thereby ensuring the reliability of the color conversion glass.

[0042] Hereinafter, the characteristics of the color conversion glass according to one embodiment of the present invention described so far will be specifically described through specific experimental examples.

[0043]

[0044] Experimental example

[0045] Table 1 shows the composition ratio and refractive index of color conversion glasses according to examples and comparative examples of the present invention. In each example and comparative example, the mol% of each component is a value calculated based on the total content of the glass composition. In this experimental example, the refractive index of the color conversion glass was aimed at being 1.6 or higher to improve the light efficiency characteristics of the color conversion glass.

[0046]

[0047]

[0048] Referring to Table 1, the glass compositions according to Examples 1 to 4 and Comparative Example 1 do not include B2O3, whereas the glass composition according to Comparative Example 2 includes B2O3. According to the above experimental examples, the refractive indices of the color conversion glasses manufactured according to Examples 1 to 4 were all 1.6 or higher, achieving the target refractive indices. However, in Comparative Example 1, where the SiO2 content exceeded 65 mol%, the melting of SiO2 was not sufficient, resulting in non-melting, and in Comparative Example 2, where the glass composition includes B2O3, it can be confirmed that the refractive index of the glass was as low as 1.4.

[0049] Table 2 shows data on the color coordinates and luminous efficiency of the color conversion glass according to Example 4 and Comparative Example 2, respectively.

[0050]

[0051]

[0052] α-SiAlON was used as the phosphor included in the color conversion glass having the composition of Example 4 and Comparative Example 2, and in Comparative Example 2, 4 wt% more phosphor was added than in Example 4 to implement the same color coordinate as Example 4. Meanwhile, in Table 2, lm means luminance efficiency, and Cx means CIE chromaticity coordinate.

[0053] Referring to Table 2, it can be confirmed that the glass according to Example 4 has improved luminous efficiency at the same color coordinates as the glass with a high refractive index compared to the glass with a low refractive index of Comparative Example 2. Specifically, while Comparative Example 2 had luminous efficiency of 19.7 at the color coordinates Cx 0.559 and Cy 0.420, the color conversion glass according to Example 4 had luminous efficiency of 19.9 at almost the same color coordinates (Cx 0.559, Cy 0.417). As a result, the color conversion glass according to Example 4 showed higher luminous efficiency than the color conversion glass according to Comparative Example 2 even though it contained less phosphor. This means that the manufacturing cost can be reduced by lowering the content of the phosphor.

[0054] Table 3 shows data regarding chemical resistance evaluation of color-conversion glasses according to Example 4 and Comparative Example 2, respectively. Color-conversion glasses according to Example 4 and Comparative Example 2 of the present invention were tested in four ways according to AEC-Q102 (optical element standard certification) presented by the Automotive Electronics Council, and the results were confirmed.

[0055]

[0056]

[0057] Referring to Table 3, it can be confirmed that the color conversion glass according to Example 4 of the present invention has improved reliability in all fields, and this is presumed to be due to the intentional exclusion of B2O3.

[0058] In this way, by manufacturing a color conversion glass from a glass composition containing SiO2, BaO, and ZnO excluding B2O3, the target refractive index can be achieved while improving the stability of the LED package.

[0059] Although the present invention has been described above with specific details such as specific components and limited examples, the above examples are provided only to help a more general understanding of the present invention, and the present invention is not limited thereto, and those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations based on this description.

[0060] Therefore, the idea of ​​the present invention should not be limited to the embodiments described above, and all things that are modified equally or equivalently to the claims described below as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

Claims

1. A glass composition for color conversion glass, 45~65mol% SiO2, 3~10mol% BaO and 10~30mol% ZnO Including, Does not contain B2O3, Glass composition.

2. In paragraph 1, Containing at least one of 3 to 8 mol% of La2O3 and ZrO2, Glass composition.

3. In paragraph 1, Further comprising 8 mol% or less of an alkali metal oxide, Glass composition.

4. In paragraph 1, A glass composition further comprising 5 mol% or less of MgO.

5. Color-changing glass manufactured by including a glass composition according to paragraph 1 and a fluorescent substance.

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