Disclosure of Invention
An alkali-free, low softening point glass is presented. The alkali-free, low softening point glass can be used to seal an OLED glass substrate to extend the life of organic materials contained in the OLED glass substrate.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition comprising:
from about 6.0 wt% to about 28.0 wt% SiO2;
From about 20.0 wt% to about 45.0 wt% of B2O3;
From about 25.0 wt% to about 48.0 wt% ZnO;
from about 0.0 wt% to about 15.0 wt% Al2O3;
From about 3.0 wt% to about 15.0 wt% CuO;
from about 0.0 wt% to about 10.0 wt% SrO; and
from about 0.0 wt% to about 5.0 wt% MgO.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition characterized by:
SiO in an amount of from 8.0 wt% to 30.0 wt%2+Al2O3,
B in a proportion of from 0.1 to 1.5% by weight2O3/ZnO, and
(SiO) in a proportion of wt.% of from 0.2 to 1.52+Al2O3)/B2O3。
According to several exemplary embodiments, the glass has a composition comprising:
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% SiO2;
From about 20.0 wt% to about 45.0 wt%, or from about 23.0 wt% to about 42.0 wt% of B2O3;
From about 25.0 wt% to about 48.0 wt%, or from about 27.0 wt% to about 48.0 wt% ZnO;
from about 0.0 wt% to about 15.0 wt%, or from about 2.0 wt% to about 11.0 wt% Al2O3;
From about 3.0 wt% to about 15.0 wt%, or from about 3.0 wt% to about 10.0 wt% CuO;
from about 0.0 wt% to about 10.0 wt%, or from about 0.5 wt% to about 10.0 wt% SrO; and
from about 0.0 wt% to about 5.0 wt%, or from about 0.5 wt% to about 5 wt% MgO.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition characterized by:
SiO in an amount of from 8.0 wt.% to 30.0 wt.%, or from 9.0 wt.% to about 28.0 wt%2+Al2O3,
B in a proportion of from 0.1 to 1.5, or from 0.5 to 1.1, wt%2O3/ZnO, and
(SiO) in a proportion of wt.% from 0.2 to 1.5, or from 0.2 to 1.22+Al2O3)/B2O3。
According to several exemplary embodiments, the alkali-free, low softening point glass has an absorption coefficient greater than about 2/mm at wavelengths from about 800nm to about 1400 nm.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition that includes less than about 1000ppm (parts per million) of alkali metals.
According to several exemplary embodiments, the alkali-free, low softening point glass has a softening point of from about 600 ℃ to about 700 ℃.
Brief description of the drawings
The following drawings are directed to the disclosed embodiments and should not be considered limiting.
FIG. 1 is a UV-VIS plot of compositions represented by example 1 in Table 3, wherein "T%" is percent transmission, "R%" is percent reflection, and "A" is absorption.
Detailed Description
When used in describing a single numeral, the term "about" is intended to encompass a range of ± 5%. When applied to a range, the term "about" means that the range includes from-5% of the numerical lower limit and + 5% of the numerical upper limit, unless the lower limit is 0. For example, a range from about 100 ℃ to about 200 ℃ includes a range from 95 ℃ to 210 ℃. However, when the term "about" modifies a percentage, such as wt%, then the term is ± 1% of the exponential or numerical boundary unless the lower limit is less than 1. Thus, a range of about 5-10% includes 4-11%, and a range of about 0-5% includes 0-6%.
The term "alkali-free" or "alkali free" refers to glass compositions that include less than about 1000ppm alkali metal, including alkali metal contained in oxides. Alkali metals include lithium, sodium, potassium, rubidium, cesium, francium.
The term "low softening point" refers to glass compositions having a softening point of from about 600 ℃ to about 700 ℃. The term "softening point" refers to a glass sample viscosity of 10 as measured by ASTM C-338 fiber lengthening7 . 6The temperature of poise.
All measurements are in metric units, unless otherwise indicated.
Unless otherwise stated, the terms "wt%" or "weight percent" of a composition of a glass composition refer to the weight percent of the composition relative to the weight of the glass composition. One skilled in the art will appreciate that the sum of the wt% must add up to 100 wt% and must not exceed 100.0 wt%.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition including SiO as a glass network forming composition2Which is almost entirely of [ SiO ]4]Present, and necessary to provide a low coefficient of thermal expansion glass. According to several embodiments, the SiO of the glass composition2The content is from about 6.0 wt% to about 28.0 wt%, from about 8.0 wt% toAbout 28.0 wt%, or from about 8.0 wt% to about 19.0 wt%. If SiO of the glass composition2When the content is reduced to less than 6.0 wt%, it becomes difficult to form glass from the composition. On the contrary, if SiO of the glass composition2The content is increased to more than 28.0 wt%, the softening point of the glass is increased to an excessively high degree and damage to the OLED substrate may be caused when the OLED substrate is sealed using the glass composition.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition comprising B as a glass network forming composition2O3Which is represented by [ BO3]And [ BO ]4]There is a reduction in the coefficient of thermal expansion of the glass and an increase in the structural integrity of the glass. At the same time, B2O3Can reduce the viscosity and softening point of the glass and accelerate the clarification. According to several exemplary embodiments, B of the glass composition2O3The amount is from about 20.0 wt% to about 45.0 wt%, or from 23.0 wt% to about 42.0 wt%. However, if B in the glass composition2O3If the amount exceeds 45 wt%, the stability of the glass is lowered and the thermal expansion coefficient is increased to an excessively high degree. If B of the glass composition2O3When the content is reduced to less than 20.0 wt%, the softening point of the glass may increase to an excessively high degree and may 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 that includes ZnO as a glass network modifier. In the glass composition, the content of ZnO tends to lower the softening point of the glass and to be able to finely adjust the thermal expansion coefficient of the glass to a desired range. According to several exemplary 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 is increased to 48.0 wt% or more, it is difficult to form glass from the composition. If the ZnO content of the glass composition is reduced below 25.0 wt%, the ability to fine tune the glass' coefficient of thermal expansion to the desired range is affected and the softening point of the glass is increased to an undesirable extent.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition that includes Al as an intermediate to the glass network2O3Which is [ AlO ]4]Are present. Containing Al in the glass composition2O3The viscosity of the glass can be increased, the possibility of devitrification of the glass is reduced, and the stability of the glass is increased. According to several exemplary embodiments, the Al of the glass composition2O3The amount is from 0 wt% to about 15.0 wt%, or from about 2.0 wt% to about 11 wt%. If Al of the glass composition2O3At levels greater than 15.0 wt%, the softening point of the glass may increase to too high a level and 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 that includes CuO as a colorant. According to several exemplary embodiments, the addition of CuO to the glass composition may allow the glass to efficiently absorb light of a long wavelength, which is suitable for a laser heating glass sealing process. However, CuO can also change the softening point of the glass. According to several exemplary embodiments, the CuO content in the glass composition is from about 3.0 wt% to about 15 wt%, or from about 3.0 wt% to about 10.0 wt%. If the CuO content of the glass composition is less than 3.0 wt%, the glass may become difficult to absorb the laser irradiation wavelength necessary in the laser heating glass sealing process. However, if the CuO content in the glass composition is increased to more than 15.0 wt%, it is difficult to form glass from the composition. According to several exemplary embodiments, the alkali-free, low softening point glass has a high laser radiation absorption capacity with an absorption coefficient greater than 2/mm at wavelengths from about 800nm to 1400 nm.
According to several exemplary 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 devitrification of the glass, and lower the liquefaction temperature of the glass. According to several exemplary 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 more than 10 wt%, the density of the glass will be too high to make the glass too heavy, and the thermal expansion coefficient of the glass will be too high, which may cause stress to adversely affect the sealing effect of the glass when the glass composition is used to seal an OLED.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition that includes MgO as an optional additive that may facilitate glass fining. According to several embodiments, the MgO content 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 more than 5.0 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 an OLED, thereby adversely affecting the sealing effect of the glass.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition characterized as having from 8.0 wt.% to 30.0 wt.%, or from 9.0 wt.% to 28.0 wt.% SiO2And Al2O3Aggregate content. According to several exemplary embodiments, SiO2And Al2O3Has an aggregate content of more than 8.0 wt.% such that the glass has a temperature range of from 50 ℃ to 300 ℃ of less than 55x10-7Coefficient of thermal expansion/° c. However, if SiO2And Al2O3With aggregate content of more than 30.0 wt%, the glass may have a softening point of more than 700 ℃, 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 of from 0.5 to 1.5, or from 0.5 to 1.12O3Wt% ratio of/ZnO. If B is present in the glass composition2O3The wt% ratio of/ZnO of less than 0.5 wt% will result in a glass having a too high coefficient of thermal expansion, which will cause stress to adversely affect the sealing effect of the glass when the glass composition is used to seal an OLED. If B is present in the glass composition2O3Wt% ratio of/ZnOAbove 1.5 wt%, the stability of the glass may be degraded and crystallization of the oxide material in the glass composition may occur.
According to several exemplary embodiments, the alkali-free, low softening point glass has a composition characterized by a wt% ratio of (SiO) of from 0.2 to 1.5, or from 0.2 to 1.22+Al2O3)/B2O3. If in the glass composition (SiO)2+Al2O3)/B2O3The wt% ratio of (B) is less than 0.2 wt%, it becomes difficult to form glass from the composition. On the contrary, (SiO) in the glass composition2+Al2O3)/B2O3With a wt% ratio of more than 1.5 wt%, the glass may have a softening point of more than 700 ℃, which may result in damage to the OLED substrate when the glass composition is used to seal the OLED substrate.
According to several exemplary embodiments, a method for making alkali-free low softening point glass is provided. According to several example embodiments, the method comprises:
weighing and mixing the raw materials;
softening the raw materials to form a homogeneous glass melt; and
cooling or water quenching the glass melt.
According to several exemplary embodiments of the methods for making alkali-free low softening point glasses described above, the glass composition is melted at about 1100 ℃ for up to about 12 hours, up to about 6 hours, or up to about 4 hours.
According to several exemplary embodiments of the methods for making alkali-free low softening point glasses described above, the glass composition is annealed at a temperature of 450 ℃ for about 2 hours, then cooled at a rate of about 1.0 ℃ per hour until the glass reaches 400 ℃, and then allowed to cool to room temperature (or about 21 ℃).
According to several exemplary embodiments of the alkali-free low softening point glass described above, the glass is a substrate for sealing an Organic Light Emitting Diode (OLED). According to several exemplary embodiments of the alkali-free, low softening point glasses described above, the glasses are used to produce touch displays, including mobile phones, tablets, ATM machines, and other electronic devices that incorporate touch displays.
The following examples are illustrative of the above compositions and methods.
Example (b):
preparation of test samples
An alkali-free low softening point glass composition comprising the composition shown in table 1 below was prepared as follows:
TABLE 1
Oxide compound
|
Mass percent (wt%)
|
SiO2 |
6.0
|
B2O3 |
40.2
|
ZnO
|
35.0
|
Al2O3 |
2.8
|
CuO
|
4.0
|
SrO
|
7.3
|
MgO
|
4.7 |
The batches shown in table 2 were weighed and mixed before being added to a 2 liter plastic container. The batch material used is of chemical grade quality.
TABLE 2
Batch of raw materials
|
Batched weight (gm)
|
Sand
|
15.01
|
Boric acid
|
179.40
|
Zinc oxide
|
88.50
|
Aluminum hydroxide
|
10.71
|
Copper oxide
|
10.10
|
Strontium carbonate
|
26.26
|
Magnesium oxide
|
11.77 |
The particle size of the sand is between 0.045 and 0.25 mm. The raw materials were mixed using a tumbler to produce a homogeneous batch and destroy soft aggregates. The mixed batch was transferred from the plastic container to an 800 ml platinum rhodium crucible for glass melting. The platinum rhodium crucible was placed in an alumina backing and loaded into a high temperature furnace equipped with a MoSi heating assembly operating at a temperature of 1000 ℃. The furnace temperature was gradually increased to 1100 ℃ and the platinum rhodium crucible and its backing were maintained at this temperature for 1 to 3 hours. While maintaining the temperature at 1100 ℃, the glass was stirred to accelerate bubble elimination and glass fining. The molten batch material was then poured from a platinum rhodium alloy crucible onto a 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, held at a temperature of 450 ℃ for two hours, and then cooled to 400 ℃ at a rate of 1 ℃/min. The samples were then allowed to cool naturally to room temperature (21 ℃) to achieve more consistent test results.
The results for the compositions shown in table 1 above are shown in the fields indicated in "example 1" in table 3 below. 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 the above example 1.
TABLE 3
Definition of symbols and measurement of physical properties
Physical properties of the glass samples were measured and are listed in table 3. The figure is a UV-VIS plot of the composition represented by example 1 in table 3, where "T%" is percent transmission, "R%" is percent reflection, and "a" is absorption.
The definitions of each symbol used in table 3 are shown below:
α: coefficient of Thermal Expansion (CTE) is the amount of change in the linear dimension from 50 to 300 ℃ as measured by ASTM-228 dilatometer;
beta: absorption coefficient at wavelength 810nm calculated from the following equation
β=-log10[T/(1-R2)]/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.
While the invention has been described with reference to certain embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
Any spatial reference terms, such as "up", "down", "between", "bottom", "vertical", "horizontal", "oblique", "up", "down", "side-by-side", "left-to-right", "up-down", "left", "right-to-left", "up-to-down", "down-to-up", "top", "bottom-top", "top-bottom", etc., are used for illustrative purposes only and do not limit the specific orientation or position of the above structure.
The invention has been described with respect to certain embodiments. It is within the spirit and scope of the present application that modifications or variations may occur to those skilled in the art upon reading this disclosure. It will be appreciated that a number of modifications, variations and alternatives are included in the foregoing disclosure and, in some instances, some features of the invention will be employed without a corresponding use of the other features. It is therefore to be understood that the appended claims may be interpreted broadly, in a manner consistent with the scope of the invention.