KR20160025478A - Non-alkali glass - Google Patents

Abstract

Provided is alkali-free glass which has the high distortion point and shows a controlled etch rate. The alkali-free glass according to the present invention contains 67-77% of SiO_2, 8-16% of Al_2O_3, 0.1-2.9% of Ba_2O_3, 2-6.5% of MgO, 5.5-12.5% of CaO, 0-8% of SrO, and 2-6% of BaO with respect of mol% of oxides, wherein MgO+CaO+SrO+BaO is 10-17.5%; (MgO+CaO+SrO+BaO)/Al_2O_3 is 2.2 or less; MgO/Ca is 0.7 or less; the weight reduction in HF is 0.16 (mg/cm^2)/min or less; the distortion point is 705°C or higher; the average thermal expansion coefficient at 50-350°C is 41.5x10^(-7)/°C or less; the specific viscosity is 2.61g/cm^2 or less; and Young′s modulus is 78 GPa or more.

Description

Non-alkali glass {NON-ALKALI GLASS}

The present invention relates to alkali-free glass. To an alkali-free glass which exhibits an appropriate etching rate, distortion point, thermal expansion coefficient and specific gravity as a glass for a substrate of a thin display.

The alkali-free glass is suitably used as a substrate glass for display purposes which is reluctant to diffuse alkali ions. A semiconductor element is formed on the substrate glass, and the glass is required to have a high distortion point and a low thermal expansion coefficient so as not to be deformed by heat applied at that time. It is also required to have a low specific gravity in order to lighten the weight.

To comply with the request, Al ₂ O ₃ and B ₂ O to control the amount of the ₃ as a pair, and the mole ratio of the amount of the Al ₂ O ₃ the amount of Al ₂ O _3, the total amount of alkaline earth metal elements and lanthanide Is limited to a predetermined value or more (Patent Document 1).

Also, in recent years, as the display becomes thinner, it is required that the glass substrate is also thin. In the display manufacturing process, the thinning process of the substrate glass is performed. The thinning process is usually performed by etching with a hydrofluoric acid chemical liquid. Therefore, from the viewpoint of productivity of the display device, a glass having a high etching rate by hydrofluoric acid is required.

In response to the above-mentioned demand, an alkali-free glass substantially not containing B ₂ O ₃ that raises the antiflatability has been proposed (Patent Document 2).

Japanese Patent Application Laid-Open No. 2009-525942 Japanese Patent Application Laid-Open No. 10-106919

If the etching rate by hydrofluoric acid is high, the thinning process can be performed quickly. On the other hand, etching unevenness occurs, the etching depth tends to become uneven, and the smoothness of the glass surface tends to be impaired. In addition, in recent years in which the thickness of the substrate glass itself is reduced, the demand for an increase in the etching rate is not always the same as before. Rather, from the viewpoint of quality improvement, it is required to set the etching rate to a controlled value in order to prevent unevenness of etching. For that purpose, but it is conceivable that increasing the B ₂ O _3, increasing the B ₂ O ₃ is reduced distortion problem, there is a problem that the thermal expansion coefficient is increased.

Accordingly, it is an object of the present invention to provide an alkali-free glass having a high distortion point, a low coefficient of thermal expansion, and a low specific gravity, and exhibiting a controlled etching rate, in accordance with this contradictory requirement.

That is,

In mole percent based on oxide,

67 to 77% of SiO ₂ ,

8 to 16% of Al ₂ O ₃ ,

B ₂ O _{3 in an amount} of 0.1 to 2.9%

2 to 6.5% of MgO,

CaO in the range of 5.5 to 12.5%

0 to 8% SrO, and

2 to 6% of BaO,

MgO + CaO + SrO + BaO is 10 to 17.5%

(MgO + CaO + SrO + BaO) / Al ₂ O ₃ is 2.2 or less,

MgO / CaO is 0.7 or less,

The weight loss of HF is 0.16 (mg / cm2) / min or less,

The distortion point is 705 DEG C or more,

The average thermal expansion coefficient at 50 to 350 DEG C is 41.5 x 10 < ^-7 > / DEG C or less,

The specific gravity is 2.61 g / cm 3 or less,

Alkali-free glass having a Young's modulus of 78 GPa or more.

In the alkali-free glass, MgO / (MgO + CaO + SrO + BaO) is preferably 0.18 or more.

The non-elasticity ratio is preferably 30 GPa · cm 3 / g or more.

In addition,

In mole percent based on oxide,

68 to 75% of SiO ₂ ,

9 to 15% of Al ₂ O ₃ ,

0.4 to 2.4% of B ₂ O ₃ ,

2.5 to 6% of MgO,

6.5 to 10% of CaO,

0 to 7% SrO, and

2.5 to 5% of BaO,

MgO + CaO + SrO + BaO of 11.0 to 16.8%

(MgO + CaO + SrO + BaO) / Al ₂ O ₃ is 1.5 or less,

MgO / CaO is 0.64 or less,

MgO / (MgO + CaO + SrO + BaO) of 0.19 or more,

HF weight loss of 0.14 (mg / cm 2) / min or less,

The distortion point is 730 DEG C or more,

The average thermal expansion coefficient at 50 to 350 占 폚 is 40 占^10-7 / 占 폚 or less,

Modulus of elasticity of 30.5 GPa · cm 3 / g or more,

The specific gravity is 2.60 g / cm 3 or less,

Alkali-free glass having a Young's modulus of 81 GPa or more.

In addition,

In mole percent based on oxide,

68.5 to 74% of SiO ₂ ,

9.5 to 14% of Al ₂ O ₃ ,

0.6 to 2.1% of B ₂ O ₃ ,

3 to 5.5% of MgO,

CaO in the range of 7.5 to 9%

0.5 to 6.5% of SrO, and

3 to 4.5% of BaO,

MgO + CaO + SrO + BaO is 11.5 to 16.5%

(MgO + CaO + SrO + BaO) / Al ₂ O ₃ is 1.3 or less,

MgO / CaO is 0.60 or less,

MgO / (MgO + CaO + SrO + BaO) is not less than 0.20,

HF weight loss of 0.13 (mg / cm 2) / min or less,

The distortion point is 740 占 폚 or more,

The average thermal expansion coefficient at 50 to 350 占 폚 is 39 占^10-7 / 占 폚 or less,

Modulus of elasticity is not less than 31 GPa · cm 3 / g,

The specific gravity is 2.59 g / cm 3 or less,

Free glass having a Young's modulus of 81.5 GPa or more.

The above alkali-free glass of the present invention (hereinafter simply referred to as "glass of the present invention") has a controlled etching rate, a high distortion point, a low thermal expansion coefficient and a low specific gravity. The glass can be suitably used in the fields of small and medium-sized LCDs, OLEDs, and particularly portable displays such as mobile phones, digital cameras and cellular phones.

In the present invention, " alkali-free " glass refers to glass substantially free of alkali metal oxides such as Na ₂ O and K ₂ O. As used herein, "substantially not contained" means that an alkali metal inevitably contained as an impurity or the like can be contained. In the present invention, the alkali metal inevitably is at most 0.1 mol%.

The alkali-free glass includes, in addition to SiO ₂ and Al ₂ O ₃ forming a glass framework, a predetermined amount of an alkaline earth metal oxide or the like. Initially, contents of these components based on oxides will be described. In the following, "%" means " mol% " unless otherwise specified.

The content of SiO ₂ is 67 to 77%, preferably 67.5 to 76%, more preferably 68 to 75%, and most preferably 68.5 to 74.0%. If the content of SiO ₂ is less than the above lower limit value, there is a tendency that the distortion point is low, the coefficient of thermal expansion and the specific gravity are high and the anti-fogging property is bad. On the other hand, if the upper limit is exceeded, the solubility tends to deteriorate such that the temperature (T ₂ ) at which the glass viscosity becomes 10 ² poas (dPa s) increases, the melt temperature increases, and the Young's modulus tends to decrease.

The content of Al ₂ O ₃ is 8 to 16%, preferably 8.5 to 15%, more preferably 9 to 15%, and most preferably 9.5 to 14%. When the content of Al ₂ O ₃ is less than the above lower limit value, the powder phase control becomes difficult, the distortion point decreases, the coefficient of thermal expansion increases, and the Young's modulus tends to decrease. On the other hand, when the upper limit is exceeded, T ₂ rises and the solubility tends to deteriorate, and the melt temperature tends to increase.

The content of B ₂ O ₃ is 0.1 to 2.9%, preferably 0.2 to 2.7%, more preferably 0.4 to 2.4%, and most preferably 0.6 to 2.1%. When the content of B ₂ O ₃ is less than the lower limit value described above, it is difficult to obtain sufficient antiflature property. In addition, the specific gravity and the thermal expansion coefficient tend to increase. On the other hand, if the upper limit value is exceeded, the distortion point tends to decrease.

The content of MgO is 2 to 6.5%, preferably 2.5 to 6%, more preferably 2.7 to 5.8%, still more preferably 2.9 to 5.6%, and most preferably 3 to 5.5%. MgO has the effect of improving the solubility, lowering the specific gravity, increasing the Young's modulus, and improving the anti-fogging property without increasing the coefficient of thermal expansion. However, when the content of MgO is less than the above lower limit, it is difficult to sufficiently obtain these effects. On the other hand, if the upper limit value is exceeded, the release temperature becomes high.

The content of CaO is 5.5 to 12.5%, preferably 6 to 11%, more preferably 6.5 to 10%, and most preferably 7.5 to 9%. CaO has an effect of improving the solubility, increasing the Young's modulus, and lowering the release temperature without increasing the coefficient of thermal expansion. However, when the content of CaO is less than the above lower limit, it is difficult to sufficiently obtain these effects. On the other hand, when the upper limit is exceeded, the thermal expansion coefficient and the slip temperature tend to increase.

The content of SrO is 0 to 8%, preferably 0 to 7.5%, more preferably 0 to 7%, and most preferably 0.5 to 6.5%. By including SrO, the solubility tends to be good and the release temperature tends to decrease. If the content of SrO is less than the above lower limit, the solubility tends to deteriorate, and the release temperature tends to increase. On the other hand, when the upper limit is exceeded, the specific gravity and the thermal expansion coefficient are increased, the Young's modulus is lowered, and the hydrofluoric acid resistance tends to be worse. The content of SrO in the range of 0 to 8% may or may not include SrO, and the maximum content of SrO is 8%.

The content of BaO is 2 to 6%, preferably 2 to 5.5%, more preferably 2.5 to 5%, and most preferably 3 to 4.5%. If the content of BaO is less than the above lower limit value, the melt temperature rises and the solubility decreases. On the other hand, when the upper limit is exceeded, the specific gravity and the thermal expansion coefficient are increased, the Young's modulus is lowered, and the anti-flammability tends to deteriorate.

The total amount of the alkaline earth metal oxide, that is, MgO + CaO + SrO + BaO (hereinafter sometimes referred to as "RO") is 10 to 17.5% , More preferably 11.5 to 16.5%, and most preferably 15.5 to 16.5%. If the total amount is less than the lower limit value, the solubility of the glass tends to deteriorate and the melt temperature tends to increase. If the total amount exceeds the upper limit value, the distortion point decreases, the specific gravity increases, the thermal expansion coefficient tends to be high and the anti- .

The RO is less than the ratio, RO / Al ₂ O ₃ on Al ₂ O ₃ 2.2. If the ratio exceeds the above value, the coefficient of thermal expansion tends to be high. Preferably, the ratio is 1.8 or less, more preferably 1.5 or less, and most preferably 1.3 or less. The lower limit value of RO / Al ₂ O ₃ is not particularly limited, but from the viewpoint of ensuring the solubility of glass, it is preferably 0.8 or so.

The ratio of MgO to CaO and MgO / CaO is 0.7 or less. When the ratio exceeds the above value, it becomes difficult to keep the slit temperature low without lowering the distortion point. Preferably, it is 0.67 or less, more preferably 0.64 or less, and most preferably 0.60 or less. The lower limit value of MgO / CaO is not particularly limited, but is preferably about 0.2 from the viewpoint that the coefficient of thermal expansion is not made too high.

Preferably, the glass of the present invention has a ratio of MgO to the RO, MgO / RO of 0.18 or more. In this case, it is possible to achieve a low thermal expansion coefficient and specific gravity while maintaining a high distortion point, lowering the etching rate, and achieving a desirable Young's modulus. More preferably 0.19 or more, and most preferably 0.20 or more. The upper limit of the ratio is not particularly limited, but is preferably about 0.8 from the viewpoint that the release temperature is not made too high.

In addition to the above components, the glass of the present invention preferably contains ZnO, Fe ₂ O ₃ , SO ₃ , F, Cl and SnO ₂ in a total amount of 2% or less, and more preferably 2% or less, in terms of solubility, refinability, May be 1% or less, more preferably 0.5% or less.

On the other hand, it is preferable that the glass of the present invention does not substantially contain P ₂ O ₅ in order not to cause deterioration of properties of a thin film of a metal or an oxide provided on the surface of the glass plate. Further, in order to facilitate recycling of the glass, it is preferable that PbO, As ₂ O ₃ and Sb ₂ O ₃ are substantially not contained.

Next, various characteristics of the glass of the present invention having the above composition will be described. The glass shows a predetermined etching rate, and in the present invention, an HF weight reduction amount is used as an index of the etching rate. The HF weight reduction amount is defined as a mass reduction amount ((mg / cm 2) / minute) per unit area and unit time when the glass is immersed in a 5 mass% hydrofluoric acid aqueous solution (HF) at 25 ° C. As will be described later, when the glass of the present invention is of a plate type, it is preferable that the thickness thereof is 0.1 to 0.7 mm, and the target of the preferable etching rate in this case is an HF weight loss amount of 0.16 (mg / cm 2) / min or less . If the HF weight reduction amount is less than the above value, uniform etching without any unevenness of etching can be realized. Preferably, the HF weight loss is 0.15 (mg / cm2) / min or less, more preferably 0.14 (mg / cm2) / min or less, and most preferably 0.13 (mg / cm2) / min or less. The lower limit of the weight loss of HF is not particularly limited, but is preferably 0.02 (mg / cm2) / min or more from the viewpoint of productivity of the display device.

The glass of the present invention has a distortion point of 705 占 폚 or higher. The glass having a distortion point above the above value can achieve a high yield without causing a problem due to heat shrinkage in a display manufacturing process. Preferably, the distortion point is 710 ° C or higher, more preferably 720 ° C or higher, more preferably 730 ° C or higher, still more preferably 735 ° C or higher, and most preferably 740 ° C or higher. Although the upper limit value of the distortion point is not particularly limited, if the distortion point is too high, it is necessary to increase the temperature of the molding apparatus accordingly, and the life of the molding apparatus tends to be lowered.

The glass of the present invention has an average thermal expansion coefficient at 50 to 350 占 폚 of 41.5 占^10-7 / 占 폚 or less. Glass having an average thermal expansion coefficient lower than the above value is resistant to thermal shock in the display manufacturing process and can achieve a high yield. Preferably, the average thermal expansion coefficient of 41 × 10 or less ^{-7 / ℃, 40 × 10 -7} / ℃ it is preferable and most preferably not more than, 39 × 10 ^-7 / ℃ than or less. The lower limit value of the average thermal expansion coefficient is not particularly limited, but the actual phase is about 30 × 10 ^-7 / ° C.

The glass of the present invention has a specific gravity of 2.61 g / cm 3 or less. Glass having a specific gravity less than the above value does not cause a problem due to warping in a display manufacturing process, and can contribute to weight reduction of a product. Preferably, the specific gravity is 2.60 g / cm 3 or less, more preferably 2.59 g / cm 3 or less, and further preferably 2.57 g / cm 3 or less. The lower limit of the specific gravity is not particularly limited, but is preferably 2.4 g / cm < 3 > or more in practice.

The glass of the present invention has a Young's modulus of 78 GPa or more. The high Young's modulus improves the fracture toughness of the glass, and is suitable for glass substrates for various displays and glass substrates for photomasks which require enlargement of the glass plate and thinning. Preferably 79 GPa or higher, more preferably 80 GPa or higher, even more preferably 81 GPa or higher, and most preferably 81.5 GPa or higher.

Further, the glass of the present invention preferably has a non-elasticity modulus (Young's modulus / specific gravity) of 30 GPa · cm 3 / g or more, and self-weight warpage is reduced. This makes it suitable for various glass substrates for displays and glass substrates for photomasks, which are required to be made larger in size and thinner because of less deformation due to self-weight deflection in the manufacturing process. More preferably 30.5 GPa · cm 3 / g or more, and most preferably 31 GPa · cm 3 / g or more.

The glass of the present invention preferably has a temperature T ₂ of 18 ° C or lower, more preferably 1780 ° C or lower, at which the viscosity becomes 10 ² poise (dPa · s). When the temperature T ₂ is less than the above value, melting of the glass raw material is relatively easy.

In the glass of the present invention, the temperature T ₄ at which the viscosity becomes 10 ⁴ poises (dPa s) is preferably 1400 캜 or lower, and more preferably 1370 캜 or lower. Glass having a temperature T ₄ less than or equal to the above value is suitable for molding by the float method.

From the same point of view as the distortion point, the glass transition point Tg is preferably 760 DEG C or more. More preferably 770 DEG C or higher, and most preferably 780 DEG C or higher.

The glass of the present invention can be made, for example, by the following method. The raw materials of the respective components are combined so as to include the predetermined composition, and the resulting mixture is continuously introduced into a melting furnace and heated at 1500 to 1800 캜 for dissolution to obtain a molten glass. The obtained molten glass is molded into a glass ribbon having a predetermined thickness by a molding apparatus, and after the glass ribbon is cooled, it is cut.

In the present invention, it is preferable to carry out the molding by a float method, a fusion method or the like. By using the fusion method, the average cooling rate near the glass transition point becomes faster, and the surface roughness of the glass plate on the side of the side subjected to the etching treatment becomes smaller when the obtained glass plate is further thinned by the hydrofluoric acid etching treatment. The float method is preferable in that it can stably produce a large plate glass (for example, one side of 2 m or more).

The thickness of the plate glass after molding is preferably thin, preferably 0.7 mm or less, more preferably 0.6 mm or less, and most preferably 0.5 mm or less, from the viewpoint of manufacturing a thin display device. The lower limit of the thickness is not particularly limited, but is preferably 0.1 mm or more, and more preferably 0.2 mm or more, in order to avoid problems due to self-weight deflection during display manufacture.

In the display manufacturing process, the plate glass is immersed in a chemical liquid containing, for example, hydrofluoric acid (HF), so that at least one main surface thereof is etched to a depth of 5 mu m or more from the surface. When the HF weight reduction amount is used, an etching rate of about 0.1 탆 / minute to about 0.7 탆 / minute is obtained when 5 mass% hydrofluoric acid is used, so that etching is performed at a uniform depth and without damaging the smoothness of the glass surface Do.

Although etching treatment can be performed with an alkaline chemical solution, it is preferable that the chemical solution containing hydrofluoric acid is etched without damaging the smoothness of the glass surface. The concentration of hydrofluoric acid contained in the chemical solution is usually about 1 to 50 mass%, particularly about 2 to 15 mass%, but is not particularly limited to this value. In addition to hydrofluoric acid, acids other than hydrofluoric acid such as hydrochloric acid, nitric acid, and sulfuric acid may be added to the chemical liquid. By immersing it for a predetermined time in accordance with the fluorine concentration in the chemical liquid, a predetermined alkali-free glass substrate is obtained.

[Example]

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

The raw materials of the respective components were combined so that the glass composition had the target composition (glass composition (unit: mol%) based on the oxides) shown in Tables 1 to 5 and melted at a temperature of 1650 ° C for 4 hours using a platinum crucible . After dissolution, the solution was cast on a carbon plate, held at a glass transition point + 30 占 폚 for 60 minutes, and then cooled to room temperature at 1 占 폚 / minute to obtain a plate-shaped glass plate. Various evaluations were made using this glass plate. Examples 1 to 16 and 20 to 23 are Examples of the present invention (Examples), and Examples 17 to 19 are Comparative Examples (Comparative Examples).

The glass composition (unit: mol%) and specific gravity (unit: g / cm 3) (measured by Archimedes method) and Young's modulus (unit: GPa) (measured by ultrasonic method) (Units: degrees Celsius) (measured by the fiber method described in JIS R3103: 2001), glass transition point Tg (unit: degrees Celsius), 50 ° C to 350 ° C (Unit: 占^10-7 / 占 폚), a temperature T ₂ (temperature at which the glass viscosity? Becomes 10 ² poise, unit: 占 폚) which is a target of solubility and a floatability and a fusion molding the temperature at which the target sex T ₄ (glass viscosity η of 10 ⁴ poise, the temperature is, the unit: ℃) (measured by a rotational viscometer), HF weight decrease amount (unit: (mg / ㎠) / minute) shows a. In Tables 1 to 5, values indicated by parentheses are calculated values.

The weight loss amount of HF was measured as follows. The glass plate obtained as described above was cut and mirror-polished on both sides to obtain a glass sample 40 mm square and 1 mm thick. This glass sample was washed, dried and mass was measured. Subsequently, the glass sample was immersed in 5 mass% hydrofluoric acid maintained at 25 占 폚 for 20 minutes, washed and dried, and the mass after immersion was measured to calculate the amount of mass reduction before immersion. Agitation was not performed because the etching rate fluctuated when the chemical solution was stirred during the immersion. The surface area was calculated from the sample dimensions, the mass reduction amount was divided by the surface area, and then divided by the immersion time to obtain a mass reduction amount (HF weight reduction amount) per unit area and unit time.

As shown in Table 4, in Example 17 including RO exceeding the range of the present invention, the HF weight reduction amount is large. Example 18 is a composition range of the invention described in Patent Document 2, and has a small HF weight reduction amount, but has a high thermal expansion coefficient and a large specific gravity. Example 19 has the range of the invention disclosed in Patent Document 1, and has many B ₂ O ₃ and MgO / CaO, and low distortion points. On the other hand, as shown in Tables 1 to 3 and 5, Examples 1 to 16 and 20 to 23 satisfying the requirements of the present invention all exhibited HF weight loss, thermal expansion coefficient, and specific gravity Or less.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

The present application is based on Japanese Patent Application No. 2014-172477 filed on August 27, 2014, the contents of which are incorporated herein by reference.

The alkali-free glass of the present invention has a high distortion point, a low thermal expansion coefficient, a small specific gravity, and a controlled etching rate, and is suitable as a high-quality glass for display.

Claims (5)

In mole percent based on oxide,
67 to 77% of SiO ₂ ,
8 to 16% of Al ₂ O ₃ ,
B ₂ O _{3 in an amount} of 0.1 to 2.9%
2 to 6.5% of MgO,
CaO in the range of 5.5 to 12.5%
0 to 8% SrO, and
2 to 6% of BaO,
MgO + CaO + SrO + BaO is 10 to 17.5%
(MgO + CaO + SrO + BaO) / Al ₂ O ₃ is 2.2 or less,
MgO / CaO is 0.7 or less,
The weight loss of HF is 0.16 (mg / cm2) / min or less,
The distortion point is 705 DEG C or more,
The average thermal expansion coefficient at 50 to 350 DEG C is 41.5 x 10 < ^-7 > / DEG C or less,
The specific gravity is 2.61 g / cm 3 or less,
Non-alkali glass having a Young's modulus of 78 GPa or more. The alkali-free glass according to claim 1, wherein MgO / (MgO + CaO + SrO + BaO) is 0.18 or more. The alkali-free glass according to claim 1 or 2, wherein the non-elasticity modulus is 30 GPa · cm 3 / g or more. In mole percent based on oxide,
68 to 75% of SiO ₂ ,
9 to 15% of Al ₂ O ₃ ,
0.4 to 2.4% of B ₂ O ₃ ,
2.5 to 6% of MgO,
6.5 to 10% of CaO,
0 to 7% SrO, and
2.5 to 5% of BaO,
MgO + CaO + SrO + BaO of 11.0 to 16.8%
(MgO + CaO + SrO + BaO) / Al ₂ O ₃ is 1.5 or less,
MgO / CaO is 0.64 or less,
MgO / (MgO + CaO + SrO + BaO) of 0.19 or more,
HF weight loss of 0.14 (mg / cm 2) / min or less,
The distortion point is 730 DEG C or more,
The average thermal expansion coefficient at 50 to 350 占 폚 is 40 占^10-7 / 占 폚 or less,
Modulus of elasticity of 30.5 GPa · cm 3 / g or more,
The specific gravity is 2.60 g / cm 3 or less,
Non-alkali glass having a Young's modulus of 81 GPa or more. In mole percent based on oxide,
68.5 to 74% of SiO ₂ ,
9.5 to 14% of Al ₂ O ₃ ,
0.6 to 2.1% of B ₂ O ₃ ,
3 to 5.5% of MgO,
CaO in the range of 7.5 to 9%
0.5 to 6.5% of SrO, and
3 to 4.5% of BaO,
MgO + CaO + SrO + BaO is 11.5 to 16.5%
(MgO + CaO + SrO + BaO) / Al ₂ O ₃ is 1.3 or less,
MgO / CaO is 0.60 or less,
MgO / (MgO + CaO + SrO + BaO) is not less than 0.20,
HF weight loss of 0.13 (mg / cm 2) / min or less,
The distortion point is 740 占 폚 or more,
The average thermal expansion coefficient at 50 to 350 占 폚 is 39 占^10-7 / 占 폚 or less,
Modulus of elasticity is not less than 31 GPa · cm 3 / g,
The specific gravity is 2.59 g / cm 3 or less,
Non-alkali glass having a Young's modulus of 81.5 GPa or more.