KR20160071356A - Non-alkali glass - Google Patents

Abstract

Alkali glass which can combine both cracking resistance and chemical resistance even when the content of B ₂ O _{3 in} the glass composition is small and contains 66 to 78% of SiO _{2 and 8 to} 15% of Al ₂ O _{3 in} mole% 0 to 8% of B ₂ O ₃ , 0 to 8% of MgO, 1 to 15% of CaO, 0 to 8% of SrO and 1 to 8% of BaO, substantially no alkali metal oxide, Lt; 0 > C.

Description

Non-alkali glass {NON-ALKALI GLASS}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-alkali glass, and more particularly to a non-alkali glass suitable for an organic EL display.

BACKGROUND ART [0002] Electronic devices such as organic EL displays are thin and have excellent video display and low power consumption, and thus are used for displays of mobile phones and the like.

Glass plates are widely used as substrates for organic EL displays. The glass plate for this purpose mainly requires the following characteristics. In particular, the following requirement (2) is important.

(1) The alkali metal oxide should not be substantially contained in order to prevent the alkali ions from diffusing into the semiconductor material formed in the heat treatment step.

(2) The reasons for the reduction of heat shrinkage of the glass sheet in the p-Si TFT manufacturing process should be high.

(3) In order to reduce the cost of the glass plate, the productivity should be excellent.

(4) High chemical resistance so as not to be deteriorated by chemicals such as acids and alkalis used in photoetching process, especially fluorochemicals.

(5) Young's modulus, Young's modulus / density (non-Young's modulus) should be high in order to reduce the warpage of the glass plate during the display manufacturing process when the glass plate becomes large and thin.

Japanese Patent No. 3804112

In a panel maker of an organic EL display, a plurality of devices are manufactured on a large glass plate formed by a glass maker, and then divided into individual devices to cut costs (so-called multi-surface formation). In this multi-surface forming step, the two glass plates are bonded after the glass plate is cut off, or after the bonding, the organic EL display is completed by cutting, so that no chamfering is performed around the glass plate, To a post-process, or to a final product in many cases. Due to such circumstances, it is important to improve the crack resistance in the case of performing the multi-surface formation.

Further, according to the detailed experiments of the inventors of the present invention, it is effective to reduce the content of B ₂ O _{3 in} the glass composition in order to satisfy the above requirement (2). However, if the content of B ₂ O _{3 in} the glass composition is reduced, the crack resistance tends to decrease. Further, when the content of B ₂ O _{3 in} the glass composition is reduced, the chemical resistance and the melting property are easily lowered, and it becomes difficult to satisfy the requirements (3) and (4).

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an alkali-free glass which can combine crack resistance and chemical resistance even when the content of B ₂ O _{3 in} the glass composition is small.

As a result of repeating various experiments, the inventors of the present invention have found out that the above-mentioned technical problem can be solved by strictly regulating the glass composition range of the alkali-free glass and regulating the glass characteristic to a predetermined range, . That is, the alkali-free glass of the present invention is characterized in that the glass composition contains 66 to 78% of SiO ₂ , _{8 to} 15% of Al ₂ O ₃ , 0 to 1.8% of B ₂ O ₃ , 0 to 8% of MgO, 15%, 0 to 8% of SrO, and 1 to 8% of BaO, substantially free of an alkali metal oxide, and having a melting point higher than 725 ° C. Here, "substantially free of alkali metal oxide" means that the content of alkali metal oxide (Li ₂ O, Na ₂ O, K ₂ O) in the glass composition is 0.5 mol% or less. &Quot; Defect point " refers to a value measured based on the method of ASTM C336.

Secondly, the alkali-free glass of the present invention preferably has a B ₂ O ₃ content of less than 0.1 mol%.

Third, the alkali-free glass of the present invention preferably has a B ₂ O ₃ content of 0.1 mol% or more and less than 1 mol%.

Fourth, the alkali-free glass of the present invention preferably contains 0.001 to 1 mol% of SnO ₂ as a glass composition.

Fifth, the alkali-free glass of the present invention preferably has a Young's modulus greater than 78 kPa. Here, the " Young's modulus " can be measured by the bending resonance method.

Sixth, the alkali-free glass of the present invention preferably has a Young's modulus / density of greater than 29.5 cd / g · cm ^-3 . Here, the " density " can be measured by the Archimedes method.

Seventh, it is preferable that the alkali-free glass of the present invention has a liquidus temperature lower than 1260 캜. Here, the " liquid phase temperature " is the temperature at which the glass powder passing through the standard 30 mesh (500 mu m) and remaining in the 50 mesh (300 mu m) is put in a platinum boat, held for 24 hours in a temperature gradient, . ≪ / RTI >

Eighth, it is preferable that the alkali-free glass of the present invention has a temperature of 1720 DEG C or lower at a viscosity of 10 ^2.5 poise. Here, the " temperature at a viscosity of 10 ^2.5 poise " can be measured by a platinum spherical impression method.

Ninth, the alkali-free glass of the present invention preferably has a viscosity (liquid viscosity) at a liquidus temperature of 10 ^4.8 poises or more. Here, " viscosity at liquid temperature " can be measured by a platinum spherical impression method.

Preferably, the alkali-free glass of the present invention is formed by an overflow down-draw method.

Eleventh, the alkali-free glass of the present invention is preferably used in an organic EL device, particularly an organic EL display.

In the alkali-free glass of the present invention, the reason why the content of each component is limited as described above will be described below. In the description of the content of each component, "%" represents mol%.

SiO ₂ is a component forming a glass framework. The content of SiO ₂ is 66 to 78%, preferably 69 to 76%, 70 to 75% or 71 to 74%, particularly preferably 72 to 73%. When the content of SiO ₂ is too small, it is difficult to increase the point of the dew point, and the density becomes too high. On the other hand, if the content of SiO ₂ is excessively high, high-temperature viscosity tends to be high and meltability tends to be lowered, and also crystal lattice such as cristobalite precipitates and the liquid phase temperature tends to be high.

Al ₂ O ₃ is a component that forms a glass skeleton and is a component that increases the fugitive point and further inhibits the powder phase. The content of Al ₂ O ₃ is 8 to 15%, preferably 9 to 14%, 9.5 to 13% or 10 to 12%, particularly preferably 10.5 to 11.5%. When the content of Al ₂ O ₃ is too small, the point is easily lowered, and the glass is liable to be dispersed. On the other hand, if the content of Al ₂ O ₃ is excessively large, a crystal of mullite or precipitated crystals such as pearlite precipitates and the liquid phase temperature tends to be high.

If the content of B ₂ O ₃ is excessively high, crack resistance and chemical resistance are likely to be deteriorated in addition to the point that the point is greatly reduced. Therefore, the content of B ₂ O ₃ is 1.8% or less, preferably 1.5% or less, 1% or less, 1% or 0.7% or less, particularly preferably 0.6% or less. On the other hand, when a small amount of B ₂ O ₃ is introduced, the crack resistance is improved and the meltability and resistance to devitrification are improved. Therefore, the content of B ₂ O ₃ is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, or 0.4% or more, particularly preferably 0.5% or more.

MgO is a component that improves the melting property by lowering the high temperature viscosity. The content of MgO is 0 to 8%, preferably 0 to 5%, 0 to 4%, 0.01 to 3.5%, 0.1 to 3.2% or 0.5 to 3%, particularly preferably 1 to 2.7%. If the content of MgO is too large, the point is easily lowered.

The content of B ₂ O ₃ + MgO (the sum of B ₂ O ₃ and MgO) is preferably 6% or less, 0.1 to 5% or 1 to 4.5%, particularly preferably 2 to 4% %to be. If the content of B ₂ O ₃ + MgO is too small, the meltability, crack resistance and chemical resistance tend to decrease.

The molar ratio B ₂ O ₃ / MgO is preferably 0.3 or less, 0.25 or less, 0.22 or less, 0.01 to 0.2 or 0.05 to 0.18, particularly preferably 0.1 to 0.17. By doing so, it becomes easy to control the resistance to devitrification in an appropriate range.

CaO is a component that remarkably improves the meltability by lowering the high temperature viscosity without lowering the point. In addition, CaO is a component of the alkaline earth metal oxide which lowers the raw material cost because the starting material is relatively inexpensive. The content of CaO is 1 to 15%, preferably 3 to 12%, 4 to 10%, or 4.7 to 8.9%, particularly preferably 5.8 to 8.5%. If the content of CaO is too small, it is difficult to enjoy the above effect. On the other hand, if the content of CaO is too large, the coefficient of thermal expansion becomes excessively high, and the balance of components of the glass composition is impaired, and the glass is liable to fail.

SrO is a component that inhibits powder phase separation and improves resistance to devitrification. Further, it is a component which lowers the high temperature viscosity to lower the melting point and increases the melting property, and is a component which suppresses the rise of the liquid phase temperature. The content of SrO is 0 to 8%, preferably 0.1 to 6%, 0.5 to 5% or 0.8 to 4%, particularly preferably 1 to 3%. When the content of SrO is too small, it is difficult to enjoy the effect of suppressing the powder phase and the effect of increasing the resistance to devitrification. On the other hand, if the content of SrO is excessively large, the component balance of the glass composition is impaired and the strontium silicate-based transition metal crystals tend to precipitate.

BaO is a component that significantly improves insolubility among alkaline earth metal oxides. The content of BaO is 1 to 8%, preferably 2 to 7%, 3 to 6% or 3.5 to 5.5%, particularly preferably 4 to 5%. If the content of BaO is too small, the liquidus temperature becomes high, and resistance to devitrification tends to decrease. On the other hand, if the content of BaO is too large, the balance of the components of the glass composition is impaired, and the crystal of BaTaO 3 is liable to precipitate.

The RO (sum of MgO, CaO, SrO and BaO) is preferably 12 to 18%, 13 to 17.5% or 13.5 to 17%, particularly preferably 14 to 16.8%. If the content of RO is too small, the meltability tends to decrease. On the other hand, if the content of RO is too large, the component balance of the glass composition is impaired and the resistance to devitrification tends to decrease.

The molar ratio MgO / RO is preferably 0.3 or less, 0.25 or less, 0.22 or less, 0.01 to 0.2 or 0.05 to 0.18, particularly preferably 0.1 to 0.17. In this case, deterioration of the point of weakening, crack resistance and chemical resistance can be suppressed easily.

The molar ratio CaO / RO is preferably 0.8 or less, 0.7 or less, 0.1 to 0.7, 0.2 to 0.65 or 0.3 to 0.6, particularly preferably 0.45 to 0.55. In this case, the resistance to devitrification and the meltability can be easily optimized.

The molar ratio SrO / RO is preferably 0.4 or less, 0.35 or less, 0.3 or less, 0.01 to 0.2 or 0.03 to 0.18, particularly preferably 0.05 to 0.15. In this case, precipitation of the strontium silicate-based transition metal crystals can be suppressed easily.

The molar ratio BaO / RO is preferably 0.5 or less, 0.4 or less, 0.1 to 0.37 or less, 0.2 to 0.35 or 0.24 to 0.32, and particularly preferably 0.27 to 0.3. By doing so, it becomes easy to increase resistance to melt while improving meltability.

In addition to the above components, for example, the following components may be added to the glass composition. The content of other components other than the above components is preferably not more than 10%, particularly preferably not more than 5%, from the viewpoint of satisfactorily enjoying the effects of the present invention.

ZnO is a component that improves the melting property. However, if a large amount of ZnO is contained, the glass tends to be easily fused and the point of the cause is easily lowered. The content of ZnO is preferably from 0 to 5%, from 0 to 3%, or from 0 to 0.5%, particularly preferably from 0 to 0.3%, and is preferably substantially free from ZnO. Here, "substantially free of ZnO" means that the content of ZnO in the glass composition is 0.2% or less.

P ₂ O ₅ is a component for increasing the point of weakness, but if P ₂ O ₅ is contained in a large amount, glass tends to be dispersed. The content of P ₂ O ₅ is preferably 0 to 1.5% or 0 to 1.2%, particularly preferably 0 to 1%.

TiO ₂ is a component that lowers the high temperature viscosity to increase the melting property and is a component that inhibits solarisation. However, when a large amount of TiO ₂ is contained, the glass tends to be colored and the transmittance tends to decrease. Therefore, the content of TiO ₂ is preferably 0 to 3%, 0 to 1%, or 0 to 0.1%, particularly preferably 0 to 0.02%.

Y ₂ O ₃ , Nb ₂ O ₅ and La ₂ O ₃ have the function of increasing the strain and Young's modulus. However, if the content of these components is too large, the density and the cost of the raw material tend to increase. Therefore, the content of Y ₂ O ₃ , Nb ₂ O ₅ and La ₂ O ₃ is preferably 0 to 3% or 0 to 1%, particularly preferably 0 to 0.1%.

SnO ₂ is a component having a good clarifying action at high temperature, a component for increasing the point of weakening, and a component for lowering the high temperature viscosity. The content of SnO ₂ is preferably 0 to 1%, 0.001 to 1%, or 0.05 to 0.5%, particularly preferably 0.1 to 0.3%. If the content of SnO ₂ is excessively large, a crystal of SnO ₂ is likely to precipitate. When the content of SnO ₂ is less than 0.001%, it is difficult to enjoy the above effect.

SnO ₂ is suitable as a fining agent, but a fining agent other than SnO ₂ may be used as long as it does not significantly impair the glass properties. Concretely, up to 1%, for example, of As ₂ O ₃ , Sb ₂ O ₃ , CeO ₂ , F ₂ , Cl ₂ , SO ₃ and C may be added in an amount of up to 1% For example, up to 1% may be added.

As ₂ O ₃ and Sb ₂ O ₃ are excellent in refinability, but it is preferable not to introduce them as far as possible from an environmental viewpoint. The content of As ₂ O ₃ is preferably not more than 0.5%, more preferably not more than 0.1%, and is preferably not substantially contained, since the content of As ₂ O ₃ is contained in a large amount in glass tends to lower the resistance to the solarisation. Here, "substantially free of As ₂ O ₃ " means that the content of As ₂ O _{3 in} the glass composition is less than 0.05%. The content of Sb ₂ O ₃ is preferably 1% or less, particularly preferably 0.5% or less, and it is preferable that Sb ₂ O ₃ is not substantially contained. Here, "substantially free of Sb ₂ O ₃ " means that the content of Sb ₂ O _{3 in} the glass composition is less than 0.05%.

Cl ₂ has an effect of accelerating the melting of alkali-free glass. When Cl ₂ is added, the melting temperature can be lowered and the action of the refining agent is promoted. As a result, the melting cost of the glass- . However, if the content of Cl ₂ is excessively large, the point is lowered. Therefore, the content of Cl ₂ is preferably 0.5% or less, particularly preferably 0.1% or less. In addition, chlorides of alkaline earth metal oxides such as strontium chloride, aluminum chloride or the like can be used as a source of introduction of Cl ₂ .

In the alkali-free glass of the present invention, the distortion point is more than 725 DEG C, preferably 730 DEG C or more, more preferably 735 DEG C or more, and further preferably 740 DEG C or more. By doing so, it is possible to suppress the heat shrinkage of the glass sheet in the manufacturing process of the p-Si TFT.

Young's modulus is preferably more than 78,, more than 78.5,, more than 79 또는 or more than 79.5,, especially more than 79.7 Pa. By doing so, it is possible to suppress warpage of the glass plate, so that handling of the glass plate in the manufacturing process of the display and the like becomes easy.

The Young's modulus / density, 9.5㎬ / g · ㎝ ^-3 exceeded, 29.8㎬ / g · ㎝ ^-3 or more, 30.1㎬ / g · ㎝ ^-3 or higher, or 30.3㎬ / g · ㎝ ^-3 or more, and particularly 30.5㎬ / g Cm < ^-3 > is preferable. If the Young's modulus / density value is increased, the amount of deflection of the glass plate can be greatly reduced.

The liquidus temperature is preferably lower than 1260 ° C or 1250 ° C or lower, particularly preferably 1240 ° C or lower. By doing so, it becomes easy to prevent the situation where the crystallization occurs during the production of glass and the productivity is lowered. Further, since the glass plate can be easily formed by the overflow down-draw method, the surface quality of the glass plate can be improved and the manufacturing cost of the glass plate can be reduced. Further, the liquidus temperature is an indicator of resistance to devitrification, and the lower the liquidus temperature, the more excellent the resistance to devitrification.

10 ^2.5 The temperature in the foam is preferably 1720 占 폚 or lower, 1700 占 폚 or lower, or 1690 占 폚 or lower, particularly 1680 占 폚 or lower. 10 ^{2.5 If} the temperature in the foam increases, it becomes difficult to ensure solubility and clarity, and the production cost of the glass plate becomes higher.

The viscosity at the liquidus temperature is preferably not less than 10 ^4.8 poise, not less than 10 ^5.0 poise, or not less than 10 ^5.2 poise, more preferably not less than 10 ^5.3 poise. This makes it easier to form a glass plate by the overflow down-draw method because it is difficult for the glass sheet to be devitrified at the time of molding. As a result, it is possible to increase the surface quality of the glass sheet, and the production cost of the glass sheet can be reduced. The liquid viscosity is an index of moldability, and the higher the liquid viscosity, the better the moldability.

In the alkali-free glass of the present invention, if the? -OH value is lowered, the defect point can be increased. The? -OH value is preferably not more than 0.5 / mm, not more than 0.45 / mm, not more than 0.4 / mm, not more than 0.35 / mm or not more than 0.3 / mm, particularly preferably not more than 0.25 / If the value of? -OH is too large, the point is easily lowered. If the value of? -OH is too small, the meltability tends to decrease. Therefore, the value of? -OH is preferably 0.01 / mm or more, particularly preferably 0.05 / mm or more.

As a method for lowering the? -OH value, the following methods can be mentioned. (1) Select raw materials with low water content. (2) Add a component (Cl, SO _3, etc.) that lowers the value of β-OH in the glass. (3) reduces moisture content in the furnace atmosphere. (4) N ₂ bubbling is performed in the molten glass. (5) Small melting furnace is adopted. (6) Increase the flow rate of the molten glass. (7) Electric melting method is adopted.

Here, the "? -OH value " indicates the value obtained by measuring the transmittance of glass using FT-IR and using the following equation.

? -OH value = (1 / X) log (T ₁ / T ₂ )

In the formula, X is a glass thickness (㎜), T ₁ is the transmittance (%) at the reference wavelength 3846㎝ ^-1, T ₂ is the minimum transmittance (%) in the vicinity of the hydroxyl group absorption wavelength 3600㎝ ^-1 to be.

The alkali-free glass of the present invention is preferably formed by molding in an overflow down-draw method. The overflow down-draw method is a method in which a molten glass is flooded from both sides of a heat-resistant trough-like structure, and the molten glass overflows downward while joining the molten glass at the lower end of the trough structure. In the overflow down-draw method, the surface to be the surface of the glass plate is not contacted with the gutter-type refractory, but is formed in the state of the free surface. Therefore, it is possible to produce a glass plate having a good surface quality with non-annealing at low cost. The structure and material of the trough-shaped structure used in the overflow down-draw method are not particularly limited as long as the desired dimensions and surface precision can be realized. There is also no particular limitation on a method of applying a force when downward drawing is performed. For example, a method may be employed in which a heat resistant roll having a sufficiently large width is rotated while being in contact with the glass, or a method in which a plurality of pairs of heat resistant rolls are drawn in contact with only the vicinity of the end face of the glass .

In addition to the overflow down-draw method, it is also possible to form a glass plate by a down-draw method (slot-down method, etc.), a float method or the like.

The alkali-free glass of the present invention is preferably used in an organic EL device, particularly an organic EL display. In the panel maker of the organic EL display, a plurality of devices are manufactured on a large glass plate formed by a glass maker, and then divided into individual devices to cut costs (so-called multi-surface formation). Particularly in the use of TVs, the devices themselves are large-sized, and large-sized glass plates are required to form these devices on multiple surfaces. Since the alkali-free glass of the present invention has a low liquidus temperature and a high liquidus viscosity, it is easy to form a large-sized glass plate, and this requirement can be satisfied.

In the alkali-free glass of the present invention, the thickness (plate thickness) is preferably 0.7 mm or less, 0.5 mm or less, 0.4 mm or less or 0.3 mm or less, particularly 0.05 to 0.1 mm. The smaller the thickness, the easier it is to make the display lightweight, thin, and flexible.

Example

Hereinafter, the present invention will be described on the basis of examples. However, the following embodiments are merely examples. The present invention is not limited to the following embodiments.

Tables 1 to 3 show Examples (Sample Nos. 1 to 14) and Comparative Examples (Sample Nos. 15 to 17) of the present invention.

First, the glass batch in which the glass raw materials were combined was placed in a platinum crucible so that the glass composition in the table was melted for 24 hours at 1600 to 1650 占 폚. When the glass batch was dissolved, the mixture was stirred using a platinum stirrer and homogenized. Subsequently, the molten glass was flowed out onto the carbon plate to be formed into a plate shape, and then slowly cooled for 30 minutes at a temperature near the stand-by point. The average thermal expansion coefficient in the temperature range of the density, 30~380 ℃ for each sample obtained CTE, Young's modulus, the Young's modulus ratio, waejeom Ps, standing cold spot Ta, the softening point Ts, the high temperature viscosity of 10 ⁴ poises at the temperature, high temperature viscosity 10 ³ Temperature and temperature at 10 poise, viscosity at 10 ^2.5 , viscosity at liquid phase temperature (TL), and viscosity at liquid temperature (liquid viscosity log _10? TL) were evaluated.

The density is measured by the Archimedes method.

The average thermal expansion coefficient CTE in the temperature range of 30 to 380 占 폚 is a value measured with a dilatometer.

The Young's modulus is a value measured by the bending resonance method.

The Young's modulus (Young's modulus / density) is a value obtained by dividing the Young's modulus measured by the bending resonance method by the density measured by Archimedes' method.

The point Ps, the standing point Ta, and the softening point Ts are values measured based on the method of ASTM C336.

The temperature at a high temperature viscosity of 10 ⁴ poise, 103 poise, 10 ^2.5 poise was measured by a platinum spherical impression method.

The liquidus temperature TL is a value obtained by passing the glass powder passing through a standard 30 mesh (500 mu m) and remaining in 50 mesh (300 mu m) into a platinum boat, holding it in a temperature gradient for 24 hours to measure the temperature at which crystals precipitate . The viscosity at the liquidus temperature is a value measured by a platinum spherical impression method.

The crack resistance was evaluated in the following manner. First, each sample was placed on a stage of a Vickers hardness tester in a constant-temperature and constant humidity chamber maintained at a humidity of 30% and a temperature of 25 ° C, and a Vickers indenter (diamond-shaped diamond indenter) was attached to the glass surface (optical polishing surface) Press for a second. Then, the number of cracks generated from the four corners of the indentation is counted up to 15 seconds after the removal, and the ratio to the maximum number of cracks (4) is determined to be the crack occurrence rate. The crack occurrence rate was measured 20 times under the same load, and the average value was obtained. Finally, the load at the time when the crack incidence rate became 50% was taken as the crack resistance value, the case where the crack resistance value was 140 gf or more was evaluated as " ", and the case where the crack resistance value was less than 140 gf was evaluated as "

The chemical resistance was evaluated as follows. First, both surfaces of each sample were optically polished, and a part of them was masked and immersed in a 63BHF solution (HF: 6% by mass, NH ₄ F: 30% by mass) at 20 ° C for 30 minutes. After the immersion, the mask was removed, and the step difference between the mask part and the erosion part was measured by a surface roughness meter, and the value was regarded as the erosion amount. The erosion amount of 8.0 탆 or less was evaluated as " did.

(Industrial availability)

The alkali-free glass of the present invention can be used for a flat panel display such as a liquid crystal display, an organic EL display and the like, as well as a cover glass for image sensors such as a charge coupled device (CCD), a close proximity type solid state image pickup device (CIS) Cover glass, glass plate for organic EL lighting, and the like.

Claims (11)

The glass composition contains 66 to 78% of SiO ₂ , 8 to 15% of Al ₂ O ₃ , 0 to 1.8% of B ₂ O ₃ , 0 to 8% of MgO, 0 to 15% of CaO, 0 to 8% of SrO, 1 to 8%, substantially free of an alkali metal oxide, and having a melting point higher than 725 ° C. The method according to claim 1,
Wherein the content of B ₂ O ₃ is less than 0.1 mol%. The method according to claim 1,
Wherein the content of B ₂ O ₃ is 0.1 mol% or more and less than 1 mol%. 4. The method according to any one of claims 1 to 3,
An alkali-free glass characterized by containing 0.001 to 1 mol% of SnO ₂ as a glass composition. 5. The method according to any one of claims 1 to 4,
Wherein the Young's modulus is larger than 78.. 6. The method according to any one of claims 1 to 5,
Wherein the Young's modulus / density is greater than 29.5 kPa / g · cm ^-3 . 7. The method according to any one of claims 1 to 6,
Wherein the liquidus temperature is lower than 1260 占 폚. 8. The method according to any one of claims 1 to 7,
Wherein the temperature at a viscosity of 10 ^2.5 Pa · s is at most 1720 ° C. 9. The method according to any one of claims 1 to 8,
Wherein the viscosity at the liquidus temperature is not less than 10 ^4.8 poise. 10. The method according to any one of claims 1 to 9,
Characterized in that the alkali-free glass is formed by an overflow down-draw method. 11. The method according to any one of claims 1 to 10,
An alkali-free glass characterized by being used in an organic EL device.