TWI702195B - Alkali-free, low softening point glass and compositions and methods thereof - Google Patents

Abstract

Alkali-free, low softening point glass compositions are presented herein. The glass composition contains SiO₂, B₂O₃, ZnO, Al₂O₃ and CuO, as well as SrO and MgO as optional additives. The glass compositions are free of alkali metal and produce glass having a softening point of from 600 ℃ to about 700 ℃, and a coefficient of linear expansion (CTE) of from about 35 x 10^-7/℃ to about 55 x 10^-7/℃ at a temperature of from 50℃ to 300℃. The glass may be used to seal organic light-emitting diode (OLED) dispoays to extend the life of the organic materials used to make the diodes.

Description

Alkali-free low-softening point glass and composition, and its method

The present disclosure is related to alkali-free low-softening point glass and its composition, and its manufacturing and use methods. The glass can be used to seal organic light emitting diode (OLED) displays to extend the life of the organic materials used to make the diodes.

The new generation of organic light-emitting diodes has attracted public attention because they are self-luminous, ultra-thin, flexible, fast response, and energy efficient. One of the biggest technical challenges faced during the development of OLED technology is the limited lifetime of the organic materials used to make the diodes. However, when researchers discovered that OLEDs can be sealed in low-softening point glass to provide better advantages than traditional thin film packaging and back cover packaging, this problem was solved. For example, OLEDs sealed in low-softening point glass have excellent water-soaking and gas barrier properties.

However, the use of low softening point glass has created a different set of challenges. Generally speaking, low softening point glass contains SiO ₂ -B ₂ O ₃ -ZnO, Bi ₂ O ₃ -B ₂ O ₃ , vanadate, phosphate, and alkaline glass systems. Bismuthate and vanadate are relatively expensive, and phosphate glass lacks chemical stability. Compared with Bi ₂ O ₃ -B ₂ O ₃ , vanadate, phosphate and alkaline glass systems, the SiO ₂ -B ₂ O ₃ -ZnO glass system has a higher softening point. The lowest softening point glass contains a large amount of alkali metal oxides to lower the softening point. However, a large amount of alkali metal oxide will increase the thermal expansion coefficient and reduce the weather resistance of the glass composition. At the same time, alkali metal ions tend to migrate or diffuse into other materials during high-temperature heat treatment.

Generally speaking, OLED glass substrates are alkali-free and have low coefficient of thermal expansion (CTE) (α=30 x 10 ^-7 /℃ to 38 x 10 ^-7 /℃), excellent heat resistance (strain point temperature higher than 650℃), high mechanical stability, and high softening point (above 900℃). Therefore, there is a need for glass for sealing such OLED glass substrates with low thermal expansion coefficient and low softening point. In addition, there is a need for glass that can be treated by a partial laser heating method to protect the organic materials of electronic components from damage by heat.

An alkali-free, low-softening point glass is proposed here. The alkali-free, low-softening point glass can be used to seal the OLED glass substrate to extend the life of the organic materials contained in the OLED glass substrate.

According to several example embodiments, the alkali-free, low-softening point glass has a composition including: from about 6.0 wt% to about 28.0 wt% of SiO ₂ ; from about 20.0 wt% to about 45.0 wt% of B ₂ O ₃ From about 25.0wt% to about 48.0wt% of ZnO; from about 0.0wt% to about 15.0wt% of Al ₂ O ₃ ; from about 3.0wt% to about 15.0wt% of CuO; from about 0.0wt% to about 10.0wt% SrO; and from about 0.0wt% to about 5.0wt% MgO.

According to several exemplary embodiments, the alkali-free, low-softening point glass has a composition characterized in that the content of SiO ₂ +Al ₂ O _{3 is} from 8.0 wt% to 30.0 wt %, and the ratio of B is from 0.1 to 1.5 wt %. ₂ O ₃ /ZnO, and (SiO ₂ +Al ₂ O ₃ )/B ₂ O _{3 with a} wt% ratio from 0.2 to 1.5.

According to several example embodiments, the glass has a composition including: from about 6.0 wt% to about 28.0 wt%, from about 8.0 wt% to about 28.0 wt%, or from about 8.0 wt% to about 19.0% SiO ₂ ; From about 20.0wt% to about 45.0wt%, or from about 23.0wt% to about 42.0wt% of B ₂ O ₃ ; from about 25.0wt% to about 48.0wt%, or from about 27.0wt% to about 48.0wt % ZnO; from about 0.0wt% to about 15.0wt%, or from about 2.0wt% to about 11.0wt% Al ₂ O ₃ ; from about 3.0wt% to about 15.0wt%, or from about 3.0wt% to About 10.0wt% CuO; from about 0.0wt% to about 10.0wt%, or from about 0.5wt% to about 10.0wt% of SrO; and from about 0.0wt% to about 5.0wt%, or from about 0.5wt% To about 5.0wt% of MgO.

According to several exemplary embodiments, the alkali-free, low-softening point glass has a composition characterized by: SiO ₂ +Al ₂ O ₃ in a content ranging from 8.0 wt% to 30.0 wt %, or from 9.0 wt% to about 28.0 wt% ; B ₂ O ₃ /ZnO with a weight% ratio of from 0.5 to 1.5, or from 0.5 to 1.1; and a weight ratio of (SiO ₂ +Al ₂ O ₃ )/B from 0.2 to 1.5, or from 0.2 to 1.2 ₂ O ₃ .

According to several example embodiments, the alkali-free, low-softening point glass has an absorption coefficient greater than about 2/mm at a wavelength from about 800 nm to about 1400 nm.

According to several example embodiments, the alkali-free, low-softening point glass has a composition that contains less than about 1000 ppm (parts per million) of alkali metals.

According to several example embodiments, the alkali-free, low-softening point glass has a softening point from about 600°C to about 700°C.

The description of Figure 1 below is related to the disclosed embodiments and should not be considered as limiting. Figure 1 is a UV-VIS image of the composition represented by Example 1 in Table 3, where "T%" is the transmission percentage, "R%" is the reflection percentage, and "A" is the absorption.

When used to describe a single number, the term "about" means a range including ±5%. When applied to a range, the term "about" means that the range includes -5% of the lower limit of the value and +5% of the upper limit of the value, unless the lower limit is zero. For example, the range from about 100°C to about 200°C includes the range from 95°C to 210°C. However, when the term "about" modifies a percentage, such as wt%, the term means ±1% of the number or value boundary, unless the lower limit is less than 1. Therefore, the range of about 5-10% includes 4-11%, and the range of about 0-5% includes 0-6%.

The term "alkali-free (alkali free)" refers to a glass composition containing less than about 1000 ppm of alkali metals (including alkali metals contained in oxides). Alkali metals include lithium, sodium, potassium, rubidium, cesium, and thorium.

The term "low softening point" means that the glass composition has a softening point from about 600°C to about 700°C.

The term "softening point" refers to the temperature at which the viscosity of a glass sample measured by ASTM C-338 fiber lengthening method is 10 ^7.6 poise.

Unless otherwise specified, all measurements are in metric units.

Unless otherwise stated, the term "wt%" or "weight percentage" of the composition of the glass composition refers to the weight percentage of the composition relative to the weight of the glass composition. Those skilled in the art can understand that the sum of wt% must be added to 100.0 wt%, and cannot exceed 100.0 wt%.

According to several example embodiments, the alkali-free, low-softening point glass has a composition including SiO ₂ as a glass network forming composition, which is almost entirely present as [SiO ₄ ] and is useful for providing glass with a low thermal expansion coefficient necessary. According to several embodiments, the SiO ₂ content of the glass composition is from about 6.0 wt% to about 28.0 wt %, from about 8.0 wt% to about 28.0 wt %, or from about 8.0 wt% to about 19.0 wt %. If the SiO ₂ content of the glass composition falls below 6.0 wt%, it will be difficult to form glass from the composition. Conversely, if the SiO ₂ content of the glass composition rises to more than 28.0 wt%, the softening point of the glass will increase to an excessively high degree, and the OLED substrate will be damaged when the glass composition is used to seal the OLED substrate.

According to several example embodiments, the alkali-free, low-softening point glass has a composition including B ₂ O ₃ as a glass network forming composition, which is present in [BO ₃ ] and [BO ₄ ], which can reduce The coefficient of thermal expansion of glass increases the integrity of the glass structure. At the same time, B ₂ O ₃ can reduce the viscosity and softening point of glass and accelerate clarification. According to several example embodiments, the B ₂ O ₃ content of the glass composition is from about 20.0 wt% to about 45.0 wt %, or from 23.0 wt% to about 42.0 wt %. However, if the amount of B ₂ O ₃ in the glass composition exceeds 45.0 wt %, the stability of the glass decreases, and the thermal expansion coefficient increases to an excessively high degree. If the B ₂ O ₃ content of the glass composition is reduced to less than 20.0wt%, the softening point of the glass will increase to an excessively high level, and the glass composition will cause damage to the OLED substrate when the glass composition is used to seal the OLED substrate .

According to several example embodiments, the alkali-free, low-softening point glass has a composition including ZnO as a glass network modifier. In the glass composition, the content of ZnO tends to lower the softening point of the glass, and can fine-tune the thermal expansion coefficient of the glass to a desired range. According to several example embodiments, the ZnO content of the glass composition is from about 25.0 wt% to about 48 wt%, or from about 27.0 wt% to about 48.0 wt%. However, if the ZnO content of the glass composition increases to 48.0 wt% or more, it is difficult to form glass from the composition. If the ZnO content of the glass composition drops below 25.0wt%, the ability to fine-tune the thermal expansion coefficient of the glass to a desired range will be affected, and the softening point of the glass will also increase to an undesirable level.

According to several example embodiments, the alkali-free, low-softening point glass has a composition including Al ₂ O ₃ as an intermediate of the glass network, which exists as [AlO ₄ ]. The inclusion of Al ₂ O ₃ in the glass composition can increase the viscosity of the glass, reduce the possibility of devitrification of the glass, and increase the stability of the glass. According to several example embodiments, the Al ₂ O ₃ content of the glass composition is from 0 wt% to about 15.0 wt %, or from about 2.0 wt% to about 11 wt %. If the Al ₂ O ₃ content of the glass composition is greater than 15.0 wt%, the softening point of the glass will increase to an excessively high level, and damage to the OLED substrate will be caused when the glass composition is used to seal the OLED substrate.

According to several example embodiments, the alkali-free, low-softening point glass has a composition including CuO as a colorant. According to several exemplary embodiments, adding CuO to the glass composition can effectively absorb long-wavelength light, and the long-wavelength light is suitable for the laser heating glass sealing process. However, CuO can also change the softening point of glass. According to several example embodiments, the CuO content in the glass composition is from about 3.0 wt% to about 15.0 wt%, or from about 3.0 wt% to about 10.0 wt%. If the CuO content of the glass composition is less than 3.0wt%, the glass becomes difficult to absorb the laser radiation wavelength necessary for the laser heating glass sealing process. However, if the CuO content in the glass composition increases to more than 15.0% by weight, it is difficult to form glass from the composition. According to several example embodiments, the alkali-free, low-softening point glass has high laser radiation absorption capacity, and its absorption coefficient at a wavelength from about 800 nm to 1400 nm is greater than 2/mm.

According to several example embodiments, the alkali-free, low-softening point glass has a composition that includes SrO as an optional additive. The inclusion of SrO in the glass composition can lower the softening point of the glass, reduce the occurrence of glass loss, and lower the liquefaction temperature of the glass. According to several example embodiments, the SrO content in the glass composition is from about 0.0 wt% to about 10.0 wt%, or from about 0.5 wt% to about 10.0 wt%. If the SrO content in the glass composition is greater than 10.0wt%, the density of the glass will be too high and the glass will be too heavy, and the thermal expansion coefficient of the glass will be too high, which will cause stress when the glass composition is used to seal the OLED. It adversely affects the sealing effect of the glass.

According to several example embodiments, the alkali-free, low-softening point glass has a composition that includes MgO as an optional additive, which can promote glass refining. According to several embodiments, the content of MgO in the glass composition is from about 0.0 wt% to about 5.0 wt%, or from about 0.5 wt% to about 5.0 wt%. If the content of MgO in the glass composition is higher than 5.0wt%, the thermal expansion coefficient of the glass will be too high, and stress will be generated when the glass composition is used to seal the OLED, which will adversely affect the sealing effect of the glass.

According to several example embodiments, the alkali-free, low-softening point glass has a composition characterized by having from 8.0 wt% to 30.0 wt%, or from 9.0 wt% to 28.0 wt% of SiO ₂ and Al ₂ O ₃ aggregates content. According to several example embodiments, the aggregate content of SiO ₂ and Al ₂ O ₃ is greater than 8.0 wt %, so that the glass has a thermal expansion coefficient lower than 55 x 10 ^-7 /°C in a temperature range from 50°C to 300°C. However, if the aggregate content of SiO ₂ and Al ₂ O ₃ is greater than 30.0 wt %, the softening point of the glass will be higher than 700° C., which may cause damage to the OLED substrate when the glass composition is used to seal the OLED substrate.

According to several exemplary embodiments, the alkali-free, low-softening point glass has a composition characterized by having a B ₂ O ₃ /ZnO wt% ratio of from 0.5 to 1.5, or from 0.5 to 1.1. If the wt% ratio of B ₂ O ₃ /ZnO in the glass composition is less than 0.5 wt%, the thermal expansion coefficient of the glass will be too high, and stress will be generated when the glass composition is used to seal the OLED, which will seal the glass The effect has an adverse effect. If the wt% ratio of B ₂ O ₃ /ZnO in the glass composition is greater than 1.5 wt%, the stability of the glass may be reduced, and crystallization of the oxide material in the glass composition may occur.

According to several example embodiments, the alkali-free, low-softening point glass has a composition characterized by having a weight% ratio of (SiO ₂ +Al ₂ O ₃ )/B ₂ O ranging from 0.2 to 1.5, or from 0.2 to 1.2 ₃ . If the ratio by weight of (SiO ₂ +Al ₂ O ₃ )/B ₂ O ₃ in the glass composition is less than 0.2 wt %, it becomes difficult to form glass from the composition. Conversely, if the weight% ratio of (SiO ₂ +Al ₂ O ₃ )/B ₂ O ₃ in the glass composition is greater than 1.5% by weight, the softening point of the glass will be higher than 700 ℃, and the glass composition is used Sealing the OLED substrate will cause damage to the OLED substrate.

According to several example embodiments, a method for manufacturing alkali-free low-softening point glass is provided. According to several example embodiments, the method includes: weighing and mixing raw materials; softening the raw materials to form a homogeneous glass melt; and cooling or quenching the glass melt with water.

According to several exemplary embodiments of the above-mentioned method for manufacturing alkali-free low-softening point glass Formula, the glass composition is melted at about 1100°C for about 12 hours, for about 6 hours, or for about 4 hours.

According to several exemplary embodiments of the method for manufacturing alkali-free low-softening point glass described above, the glass composition is annealed at a temperature of 450°C for about 2 hours, and then cooled at a rate of about 1.0°C per hour until the glass reaches After reaching 400°C, the glass composition is cooled to room temperature (or about 21°C).

According to several example embodiments of the above-mentioned alkali-free low-softening point glass, the glass is a substrate for sealing an organic light emitting diode (OLED). According to several example embodiments of the above-mentioned alkali-free low-softening point glass, the glass is used to produce touch displays, including mobile phones, tablets, ATM machines, and other electronic devices including touch displays.

The following examples are illustrations of the above compositions and methods.

Examples:

Preparation of test samples

Prepare the alkali-free low-softening point glass composition as shown in Table 1 as follows:

Before adding the batch materials shown in Table 2 to a 2-liter plastic container, weigh and mix them. The batch materials used are of chemical grade quality.

Table 2

The particle size of sand is between 0.045 and 0.25 mm. A drum is used to mix the raw materials to produce homogeneous batches and destroy soft aggregates. The mixed batch is transferred from the plastic container to an 800 ml platinum-rhodium alloy crucible for glass melting. The platinum-rhodium alloy crucible was placed in an alumina backing pad and loaded into a high-temperature furnace equipped with MoSi heating elements operating at a temperature of 1000°C. The furnace temperature is gradually increased to 1100°C, and the platinum-rhodium alloy crucible and its back pad are maintained at this temperature for 1 to 3 hours. While maintaining the temperature at 1100°C, stir the glass to accelerate the elimination of bubbles and the clarification of the glass. Then, the molten batch of material was poured from the platinum-rhodium alloy crucible onto the stainless steel plate to form a glass cake, thereby forming a glass sample. While the glass cake was still hot, it was transferred to an annealer, kept at a temperature of 450°C for two hours, and then cooled to 400°C at a rate of 1°C/min. Then, let the sample cool down to room temperature (21°C) to achieve more consistent test results.

The results of the composition shown in Table 1 above are shown in the column indicated by "Example 1" in Table 3 below. The other compositions shown in Table 3 and represented by "Example 2" to "Example 8" were prepared in the same manner as the composition represented by Example 1 above.

Definition of symbols and measurement of physical properties

The physical properties of the glass samples were measured and listed in Table 3. The diagram is the UV-VIS diagram of the composition shown in Example 1 in Table 3, where "T%" is the transmission percentage, "R%" is the reflection percentage, and "A" is the absorption.

The definition of each symbol used in Table 3 is shown below: α: Coefficient of Thermal Expansion (CTE) is the linear dimensional change from 50 to 300°C measured by ASTM-228 dilatometer; β: Wavelength calculated by the following equation The absorption coefficient at 810 nm β=-log ₁₀ [T/(1-R ² )]/t, where β represents the absorption coefficient, T represents the proportion of light passing through the thickness (t) of the sample, and R refers to the reflectivity ratio.

Although the present invention has been described with reference to certain embodiments, those skilled in the art will be able to implement the present invention with modifications within the spirit and scope of the attached patent application.

Reference terms in any space, such as "up", "down", "above", "below", "between", "bottom", "vertical", "horizontal", "tilt", "up", " "Down", "Side by Side", "Left to Right", "Up and Down", "Left", "Right", "Right to Left", "Top to Bottom", "Bottom to Top", "Top", "Bottom" , "Bottom-Top", "Top-Bottom", etc., are for illustrative purposes only and do not limit the specific orientation or position of the above structure.

The present invention has been described with respect to certain embodiments. Improvements or modifications that can be learned by those skilled in the art only after reading this disclosure are within the spirit and scope of this application. It should be understood that several modifications, changes, and substitutions are included in the foregoing disclosure, and in some examples, certain features of the present invention can be applied without corresponding use of other features. Therefore, it should be understood that the scope of the attached patent application can be broadly interpreted in a manner consistent with the scope of the present invention.

Claims (16)

An alkali-free low-softening point glass with a composition, the composition comprising: from about 6.0 wt% to about 28.0 wt% of SiO ₂ ; from about 20.0 wt% to about 45.0 wt% of B ₂ O ₃ ; from about 25.0 wt% wt% to about 48.0 wt% ZnO; from about 0.0 wt% to about 15.0 wt% Al ₂ O ₃ ; from about 3.0 wt% to about 15.0 wt% CuO; from 0.5 wt% to about 10.0 wt% SrO ; And from 0.5wt% to about 5.0wt% of MgO. The glass as described in item 1 of the scope of patent application, wherein the composition of the glass is characterized by having: SiO ₂ + Al ₂ O ₃ with a content of from 8.0wt% to 30.0wt%, and a ratio of from 0.5 to 1.5 wt% The ratio of B ₂ O ₃ /ZnO and wt% is from 0.2 to 1.5 (SiO ₂ +Al ₂ O ₃ )/B ₂ O ₃ . The glass according to claim 1, wherein the glass has a composition including SiO ₂ from about 8.0 wt% to about 28.0 wt%. The glass according to claim 1, wherein the glass has a composition including SiO ₂ from about 8.0 wt% to about 19.0 wt%. The glass according to claim 1, wherein the glass has a composition including B ₂ O ₃ from about 23.0 wt% to about 42.0 wt %. The glass according to the first item of the scope of patent application, wherein the glass has a composition including ZnO from about 27.0 wt% to about 48.0 wt%. The glass described in item 1 of the scope of patent application, wherein the glass has a composition including Al ₂ O ₃ from about 2.0 wt% to about 11.0 wt %. The glass according to claim 1, wherein the glass has a composition including CuO from about 3.0 wt% to about 10.0 wt%. The glass described in item 2 of the scope of patent application, wherein the composition of the glass is characterized by having a content of SiO ₂ +Al ₂ O ₃ from 9.0 wt% to 28.0 wt %. The glass described in item 1 of the scope of patent application, wherein the glass has a softening point of from about 600°C to about 700°C. The glass described in item 1 of the scope of patent application, wherein the glass has a composition characterized by having an alkali metal content of less than about 1000 parts per million. The glass described in item 1 of the scope of patent application, wherein the glass has a coefficient of thermal expansion (CTE) from about 35 x 10 ^-7 /°C to about 55 x 10 ^-7 /°C at a temperature from 50°C to 300°C . The glass described in item 1 of the scope of patent application, wherein the glass has a coefficient of thermal expansion (CTE) from about 40 x 10 ^-7 /°C to about 48 x 10 ^-7 /°C at a temperature from 50°C to 300°C . The glass according to the first item of the patent application, wherein the glass has an absorption coefficient greater than about 2/mm at a wavelength from about 800 nm to about 1400 nm. An alkali-free low-softening point glass with a composition, the composition comprising: from about 8.0 wt% to about 28.0 wt% of SiO ₂ ; from about 23.0 wt% to about 42.0 wt% of B ₂ O ₃ ; from about 27.0 wt% wt% to about 48.0 wt% ZnO; from about 2.0 wt% to about 11.0 wt% Al ₂ O ₃ ; from about 3.0 wt% to about 10.0 wt% CuO; from 0.5 wt% to about 10.0 wt% SrO ; And from 0.5wt% to about 5.0wt% of MgO. The glass as described in item 15 of the scope of the patent application, wherein the composition of the glass is characterized by having a content of SiO ₂ + Al ₂ O ₃ from 10.0wt% to 28.0wt%, and a ratio of wt% from 0.5 to 1.1 The ratio of B ₂ O ₃ /ZnO and wt% is from 0.24 to 1.2 (SiO ₂ +Al ₂ O ₃ )/B ₂ O ₃ .

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