KR20160010350A - Non-alkali glass - Google Patents

Abstract

According to the present invention, provided is non-alkali glass with low thermal expansion coefficient and high distortion point, and more specifically, with low T_2 wherein the viscosity is 10^2 dPa·s. The distortion point is higher than 695°C, and the thermal expansion coefficient is lower than 43×10^(-7)/°C at temperatures of 50-350°C. The temperature (T_2) wherein the viscosity of the glass becomes 10^2 dPa·s is below 1690°C. 63-70 mol% of SiO_2, 8-16 mol% of Al_2O_3, 1.5-4 mol% of B_2O_3, 0-8 mol% of MgO, 0-20 mol% of CaO, 1.5-10 mol% of SrO, 0-0.5 mol% of BaO are contained based on an oxide. MgO+CaO is 0-28; MgO+CaO+SrO+BaO is 12-30; and SrO/CaO is 0.33-0.85.{23.5×[SiO_2]+3.5×[Al_2O_3]-5×[B_2O_3])/(2.1×[MgO]+4.2×[CaO]+10×[SrO]+12×[BaO] is above 17.}

Description

Non-alkali glass {NON-ALKALI GLASS}

The present invention relates to an alkali-free glass which is suitable as a substrate glass for various displays or a substrate glass for a photomask, and which can be substantially floated without substantially containing an alkali metal oxide. The alkali-free glass in the present invention does not substantially contain an alkali component (i.e., except for inevitable impurities).

Conventionally, in the case of forming a metal or an oxide thin film on a substrate glass for various displays, in particular, a surface thereof, the following characteristics have been demanded.

(1) If alkali metal oxide is contained, alkali metal ions are not substantially contained because alkali metal ions diffuse into the thin film to deteriorate film characteristics.

(2) When the film is exposed to high temperature in the thin film forming process, the distortion point should be high so as to minimize the shrinkage (heat shrinkage) accompanying the deformation of the glass and the structure stabilization of the glass.

(3) It should have sufficient chemical durability against various chemicals used for semiconductor formation. In particular, it is possible to use a buffer solution containing BHF (mixed liquid of hydrofluoric acid and ammonium fluoride) for etching SiO _x or SiN _x and a chemical solution containing hydrochloric acid used for etching of ITO, various acids used for etching metal electrodes ), Durability against alkali of resist stripping solution.

(4) There shall be no defects (bubbles, spots, inclusions, pits, scratches, etc.) on the inside and on the surface.

In addition to the above requirements, the following situation has recently been encountered.

(5) Lightweight display is required, and glass itself is required to have a small density.

(6) Lightness of the display is required and thinning of the substrate glass is desired.

(7) In addition to conventional amorphous silicon (a-Si) type liquid crystal displays, a polycrystalline silicon (p-Si) type liquid crystal display having a slightly high heat treatment temperature has been produced (a- Si: 350 to 550 캜).

(8) Fabrication of liquid crystal display In order to increase the productivity by raising and lowering the heat treatment speed of the heat treatment or to increase the thermal shock resistance, a glass having an average coefficient of thermal expansion of glass is required.

On the other hand, the dryness of the etching proceeds and the demand for the BHF resistance is weakened. In order to improve the BHF resistance, glass containing 6 to 10 mol% of B ₂ O ₃ has been widely used. However, B ₂ O ₃ tends to lower the distortion point. Examples of the alkali-free glass which does not contain B ₂ O ₃ or has a low content include the following.

Patent Document 1 discloses a glass containing 0 to 3% by weight of B ₂ O ₃ , but the distortion point of the examples is 690 ° C. or less.

In Patent Document 2, a glass containing 0 to 5 mol% of B ₂ O ₃ is disclosed, but an average thermal expansion coefficient at 50 to 350 ° C. exceeds 50 × 10 ^-7 / ° C.

In order to solve the problems in the glasses disclosed in Patent Documents 1 and 2, an alkali-free glass described in Patent Document 3 has been proposed. The alkali-free glass described in Patent Document 3 has a high distortion point and can be formed by a float method, and is suitable for use as a display substrate, a photomask substrate, and the like.

Japanese Patent Application Laid-Open No. 4-325435 Japanese Patent Application Laid-Open No. 5-232458 Japanese Patent Application Laid-Open No. 9-263421

Recently, in a high-precision small-sized display such as a portable terminal such as a smart phone, a laser annealing method is adopted as a manufacturing method of a high-quality p-Si TFT, but a glass having a high distortion point is required to further reduce the heat shrinkage rate . In addition, glass substrates having a high Young's modulus and a high non-elasticity (Young's modulus / density) are required along with the planarization and thinning of glass substrates.

On the other hand, from the request in the glass manufacturing process, it is required to excessively increase the distortion point.

An object of the present invention is to solve the above drawbacks and to provide an alkali-free glass having a low thermal expansion coefficient, a high distortion point, and a low viscosity, particularly a low temperature T ₂ at which the glass viscosity is 10 ² dPa · s.

The present invention is a strain point over 695 ℃, 50 to about an average thermal expansion coefficient at 350 ℃ than 43 × 10 ^-7 / ℃, the temperature T ₂ is the glass viscosity is 10 ² d㎩ · s and less than 1690 ℃ , Expressed in mole% based on oxide

SiO ₂ 63 to 70,

Al ₂ O ₃ 8 to 16,

B ₂ O ₃ 1.5 to less than 4,

MgO 0 to 8,

CaO 0-20,

SrO 1.5 to 10,

BaO 0 to 0.5,

MgO + CaO is 0 to 28, MgO + CaO + SrO + BaO is 12 to 30, SrO / CaO is 0.33 to 0.85, and (23.5 x [SiO ₂ ] + 3.5 x [Al ₂ O ₃ ] (B ₂ O ₃ )) / (2.1 x [MgO] + 4.2 x [CaO] + 10 x [SrO] + 12 x [BaO] is 17 or more.

The alkali-free glass of the present invention is particularly suitable for substrates for displays, substrates for photomasks and the like which are used for high distortion points, and which are easy to form float. The alkali-free glass of the present invention can also be used as a glass substrate for a magnetic disk.

Next, the composition range of each component will be described. If the SiO _{2 content} is less than 63% (mol%, the same applies unless otherwise specified), the distortion point is not sufficiently increased, the thermal expansion coefficient is increased, and the density is increased. Therefore, SiO ₂ is 63% or more. Is preferably 64% or more, more preferably 65% or more, and still more preferably 66% or more. If more than 70% solubility is lowered, and the glass viscosity of 10 ² d㎩ · s is the temperature T ₂ and 10 ⁴ d㎩ · s, the temperature T ₄ which is raised increases the devitrification temperature. Therefore, SiO ₂ is 70% or less. Is preferably 69.5% or less, more preferably 69% or less, further preferably 68.5% or less.

Al ₂ O ₃ suppresses the grain refinement of the glass and lowers the thermal expansion coefficient and increases the distortion point, but when it is less than 8%, the effect is not exhibited, and the other components that increase the expansion are increased, resulting in a large thermal expansion. Therefore, Al ₂ O ₃ is 8% or more. 9% or more, 10% or more, and more preferably 11.1% or more. If it is more than 16%, the solubility of the glass may deteriorate or the melt temperature may increase. Therefore, Al ₂ O ₃ is 16% or less. Is preferably 15% or less, more preferably 14.5% or less, and even more preferably 14% or less.

B ₂ O ₃ is contained in an amount of not less than 1.5% and less than 4% in order to improve the dissolution reactivity of the glass and to lower the melting temperature. In order to obtain the above effect, the content is preferably 1.6% or more, more preferably 1.7% or more, and further preferably 1.8% or more. However, if too much, the distortion point is lowered and the Young's modulus becomes smaller, so it is less than 4%. Preferably 3.5% or less, more preferably 3% or less, still more preferably 2.8% or less, still more preferably 2.6% or less, and particularly preferably 2.5% or less.

MgO has a feature of increasing the Young's modulus while maintaining the density at a low level in the alkaline earth without increasing expansion, and may be contained to improve the solubility. In order to obtain the above effect, the content is preferably 0.1% or more, more preferably 1% or more, further preferably 2% or more, particularly preferably 3% or more. However, if it is too much, the melt temperature rises to 8% or less. , More preferably not more than 8%, more preferably not more than 7.5%, more preferably not more than 7%, even more preferably not more than 6.5% and not more than 6%.

CaO has a feature of increasing the Young's modulus while maintaining the density at a low level in the alkaline earth without increasing the expansion, and may be added to improve the solubility. In order to obtain the above effect, the content is preferably 0.1% or more, more preferably 1% or more, further preferably 3% or more, particularly preferably 5% or more. However, if it is too much, there is a possibility that the discharge temperature increases or phosphorus, which is an impurity in limestone (CaCO ₃ ) as a CaO raw material, may be incorporated a lot. Is preferably 15% or less, more preferably 12% or less, further preferably 10% or less.

SrO improves solubility without increasing the glass transition temperature, but if it is less than 1.5%, this effect does not sufficiently appear. Therefore, SrO is 1.5% or more. Is preferably 2% or more, more preferably 2.5% or more, and still more preferably 3% or more. However, if it exceeds 10%, the expansion coefficient may increase. Therefore, SrO is 10% or less. Is preferably 8% or less, more preferably 6% or less, further preferably 5% or less.

BaO may be contained for improving solubility. However, if it is too much, the expansion and density of the glass excessively increase, so it should be 0.5% or less. It is preferable that BaO does not substantially contain (i.e., exclude inevitable impurities) in consideration of environmental load.

MgO and CaO have an effect of lowering the devitrification temperature. The total amount of MgO and CaO is preferably 2% or more, more preferably 5% or more, still more preferably 8% or more, and particularly preferably 10% or more. If it is more than 28%, the coefficient of thermal expansion and the specific gravity become larger. Therefore, it should be 28% or less. Preferably 24% or less, more preferably 20% or less, and even more preferably 16% or less.

MgO, CaO, SrO, and BaO are added in an amount of 12% or more so that the temperature T ₂ at which the glass viscosity becomes 10 ² dPa · s is not excessively increased. 14% or more is preferable, 16% or more is more preferable, and 17% or more is more preferable. If it is more than 30%, the distortion point tends to be lowered. Therefore, the total amount should be 30% or less. Is preferably 25% or less, more preferably 22% or less, and most preferably 20% or less.

If SrO / CaO is smaller than 0.33, the devitrification temperature rises. Therefore, SrO / CaO should be 0.33 or more. Preferably 0.36 or more, more preferably 0.4 or more, and still more preferably 0.45 or more. If it is larger than 0.85, the thermal expansion coefficient and the specific gravity become larger. Therefore, SrO / CaO should be 0.85 or less. Is preferably 0.8 or less, more preferably 0.75 or less, still more preferably 0.7 or less.

If SrO / (MgO + CaO) is less than 0.05, the devitrification temperature tends to rise. Is preferably 0.05 or more, more preferably 0.1 or more, further preferably 0.14 or more, and still more preferably 0.18 or more. If it is larger than 4.0, the coefficient of thermal expansion and the specific gravity are liable to increase. More preferably 4.0 or less, more preferably 3.0 or less, still more preferably 2.0 or less, still more preferably 1.0 or less, and particularly preferably 0.7 or less.

(23.5 x [SiO ₂ ] + 3.5 x [Al ₂ O ₃ ] -5 x [B ₂ O ₃ ] / 2.1 x [MgO] + 4.2 x [CaO] + 10 x [SrO] + 12 x [BaO ]) Is 17 or more, the temperature T ₂ at which the glass transition point is 10 ² dPa 揃 s at a high strain point is not made too high, and the thermal expansion is not excessively increased. Preferably 17.5 or more, more preferably 18 or more, and even more preferably 18.5 or more.

Further, the glass of the present invention does not contain the alkali metal oxide in an amount exceeding (i.e., substantially) the impurity level so as not to cause characteristic deterioration of the metal or oxide thin film formed on the glass surface at the time of manufacturing the panel. 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.

For the same reason, P ₂ O ₅ is preferably substantially free. The amount of the impurities to be incorporated is preferably 23 mol ppm or less, more preferably 18 mol% or less, still more preferably 11 mol% or less, and particularly preferably 5 mol% or less.

The alkali-free glass of the present invention may contain ZnO, Fe ₂ O ₃ , SO ₃ , F, Cl and SnO ₂ in a total amount of 1% to improve the solubility, refinability and moldability (floatability) Or less, preferably 0.9% or less, more preferably 0.8% or less, further preferably 0.7% or less. It is preferable that ZnO is substantially not contained.

In addition to the above components, the alkali-free glass of the present invention may contain up to 1% of ZrO ₂ in order to lower the glass melting temperature or to improve the Young's modulus. If it exceeds 1%, the melt temperature rises. It is preferably not more than 0.7%, more preferably not more than 0.5%, further preferably not more than 0.3%, and particularly preferably substantially not.

The alkali-free glass of the present invention has a distortion point of 695 캜 or higher.

Since the alkali-free glass of the present invention has a distortion point of 695 占 폚 or higher, heat shrinkage during panel manufacture can be suppressed. As a method of manufacturing the p-Si TFT, a laser annealing method can be applied. More preferably 700 ° C or higher, more preferably 705 ° C or higher, and still more preferably 710 ° C or higher.

Since the alkali-free glass of the present invention has a distortion point of 695 占 폚 or higher, it can be used in a high distortion point application (for example, a plate thickness of 0.7 mm or less, preferably 0.5 mm or less, more preferably 0.3 mm or less, Or less, which is a thin plate, for a display or a substrate for illumination).

In the case of forming a plate glass having a plate thickness of 0.7 mm or less, further 0.5 mm or less, further 0.3 mm or less, and further 0.1 mm or less, the drawing speed at the time of molding tends to be accelerated so that the fictive temperature of the glass increases and the heat shrinkage rate It is easy to increase. In this case, the heat shrinkage can be suppressed when the glass has a high distortion point.

The glass transition point of the alkali-free glass of the present invention is preferably 730 占 폚 or higher, more preferably 740 占 폚 or higher, and even more preferably 750 占 폚 or higher for the same reason as the distortion point.

In addition, the alkali-free glass of the present invention has an average thermal expansion coefficient of 43 x 10 < ^-7 > / DEG C or less at 50 to 350 DEG C, has a high thermal shock resistance, and can increase productivity during panel manufacture. In the alkali-free glass of the present invention, the average thermal expansion coefficient at 50 to 350 ° C is preferably 42 × 10 ^-7 / ° C or less, more preferably 41 × 10 ^-7 / ° C or less, still more preferably 40 X 10 ^-7 / 占 폚 or lower, even more preferably 39.5 占^10-7 / 占 폚 or lower, particularly preferably 39 占^10-7 / 占 폚 or lower.

The specific gravity of the alkali-free glass of the present invention is preferably 2.62 or less, more preferably 2.60 or less, still more preferably 2.58 or less, still more preferably 2.55 or less.

In the alkali-free glass of the present invention, the temperature T ₂ at which the viscosity η is 10 ² poise (dPa · s) is 1690 ° C. or less, preferably 1680 ° C. or less, more preferably 1675 ° C. or less , It is relatively easy to dissolve because it is at most 1670 ° C, more preferably at most 1665 ° C.

In the alkali-free glass of the present invention, the temperature T ₄ at which the viscosity η is 10 ⁴ poise is 1310 ° C. or lower, preferably 1305 ° C. or lower, more preferably 1300 ° C. or lower, further preferably 1300 ° C. or lower, 1295 ° C or less and 1290 ° C or less, and is suitable for float forming.

In the alkali-free glass of the present invention, it is preferable that the glass transition temperature is 1315 ° C or lower because the glass transition temperature can be easily formed by the float method. Preferably 1300 DEG C or lower, 1300 DEG C or lower, 1290 DEG C or lower, more preferably 1280 DEG C or lower. In addition, the temperature T ₄ (glass viscosity η of 10 ⁴ poise, the temperature is, the unit: ℃) by which the castle float formability and fusion molding and the devitrification temperature difference (T ₄ - devitrification temperature), preferably -20 ° C or higher, -10 ° C or higher, further 0 ° C or higher, more preferably 10 ° C or higher, further preferably 20 ° C or higher, particularly preferably 30 ° C or higher.

In the present specification, the glass transition temperature is a temperature at which glass particles pulverized in a platinum dish are put into a furnace and subjected to heat treatment in an electric furnace controlled at a constant temperature for 17 hours, And the minimum temperature at which crystals are not precipitated.

In the alkali-free glass of the present invention, the Young's modulus is preferably not less than 78 하고, more preferably not less than 79,, not less than 80,, further preferably not less than 81 영, more preferably not less than 82 영.

The alkali-free glass of the present invention preferably has a photoelastic constant of 31 nm / MPa / cm or less.

The glass substrate may have birefringence due to the stress generated in the process of manufacturing the liquid crystal display panel or using the liquid crystal display device, so that the black display may become gray and the contrast of the liquid crystal display may be deteriorated. This phenomenon can be suppressed small by setting the photoelastic constant to 31 nm / MPa / cm or less. Preferably 30 nm / MPa / cm or less, more preferably 29 nm / MPa / cm or less, further preferably 28.5 nm / MPa / cm or less, particularly preferably 28 nm /

In the alkali-free glass of the present invention, the photoelastic constant is preferably 23 nm / MPa / cm or more, and more preferably 25 nm / MPa / cm or more in consideration of ease of securing different physical properties.

The photoelastic constant can be measured at a measurement wavelength of 546 nm by a disk pressing method.

Further, the alkali-free glass of the present invention preferably has a small shrinkage upon heat treatment. In the manufacture of liquid crystal panels, the array side and the color filter side are different in the heat treatment process. Therefore, when the heat shrinkage ratio of the glass is high, particularly in a high-precision panel, there is a problem that the dot is shifted when it is fitted. The evaluation of the heat shrinkage rate can be carried out by the following procedure. The sample is kept at the temperature of the glass transition point + 100 DEG C for 10 minutes and then cooled to room temperature at 40 DEG C / minute. Here, the total length of the sample is measured. Thereafter, the sample is heated to 600 ° C at a heating rate of 100 ° C per hour, held at 600 ° C for 80 minutes, cooled to room temperature every hour at a rate of 100 ° C, and then the entire length of the sample is measured again. The ratio of the shrinkage of the sample before and after the heat treatment at 600 ° C and the total length of the sample before the heat treatment at 600 ° C is taken as the heat shrinkage ratio. In the above evaluation method, the heat shrinkage rate is preferably 200 ppm or less, more preferably 150 ppm or less, further preferably 100 ppm or less, further preferably 80 ppm or less, particularly preferably 60 ppm or less.

[Example]

In the following, Examples 1 to 11 and 15 to 28 are Examples, and Examples 12 to 14 are Comparative Examples. The raw materials of each component were combined so as to be the target composition and dissolved at a temperature of 1550 to 1650 캜 using a platinum crucible. The grain size of the silica sand in the raw material was 26 탆 in median particle size D ₅₀ , less than 0.1% by volume of particles having a particle diameter of 2 탆 or less, and less than 0.1% by volume of particles having a particle diameter of 100 탆 or more. In the dissolution, the glass was homogenized by stirring using a platinum stirrer. Subsequently, the molten glass was flowed to form a plate, followed by slow cooling.

(Unit: mol%) and a thermal expansion coefficient (unit: 占 10 ^-7 / 占 폚), a distortion point (unit: 占 폚), a glass transition point (unit: 占 폚) at 50 to 350 占 폚, , The specific gravity, the Young's modulus (㎬) (measured by the ultrasonic method), the temperature T ₂ (the temperature at which the glass viscosity η becomes 10 ² poise, unit: ° C.) and a fusion temperature at which the molded based castle T ₄ (glass viscosity η of 10 ⁴ poise temperature, unit: ℃), devitrification temperature (unit: ℃), photoelastic constant (unit: ㎚ / ㎫ / ㎝) (original compression (Measured at a measurement wavelength of 546 nm) and heat shrinkage (unit: ppm). The heat shrinkage rate was evaluated in the following procedure. A glass plate specimen (mirror-polished sample of cerium oxide having a length of 100 mm, a width of 10 mm and a thickness of 1 mm) was held at a glass transition point + 100 占 폚 for 10 minutes and cooled to room temperature at 40 占 폚 per minute. Here, the total length (longitudinal direction) L1 of the sample is measured. Thereafter, it was heated from 100 ° C to 600 ° C every hour, maintained at 600 ° C for 80 minutes, cooled to room temperature every hour at 100 ° C, and the total length L2 of the sample was measured again. The ratio of the total length (L1-L2) before and after the heat treatment at 600 占 폚 to the total length L1 of the sample before heat treatment at 600 占 폚 (L1-L2) / L1 占⁶ was defined as the heat shrinkage.

In Tables 1 to 4, values enclosed in parentheses are calculated values.

As can be seen from the table, all of the glasses of the examples had a temperature T ₂ at which the distortion point was as high as 695 ° C or higher, the coefficient of thermal expansion was as low as 43 x 10 ^-7 / ° C or lower, and the glass viscosity was 10 ² dPa s Since it is not higher than 1690 占 폚, it has excellent solubility in the production of glass.

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.

 This application is based on Japanese Patent Application No. 2014-148112 filed on July 18, 2014, the content of which is incorporated herein by reference.

The alkali-free glass of the present invention has a high distortion point and can be formed by the float method, and is suitable for use as a display substrate, a photomask substrate, and the like. It is also suitable for a substrate for an information recording medium, a substrate for a solar cell, and the like.

Claims (5)

The strain point is more than 695 ℃, and 50 to the average coefficient of thermal expansion is less than 43 × 10 ^-7 / ℃ at 350 ℃, and temperature T ₂ is less than 1690 ℃ the glass viscosity is 10 ² d㎩ · s, the oxide basis As mol%
SiO ₂ 63 to 70,
Al ₂ O ₃ 8 to 16,
B ₂ O ₃ 1.5 to less than 4,
MgO 0 to 8,
CaO 0-20,
SrO 1.5 to 10,
BaO 0 to 0.5,
MgO + CaO is 0 to 28, MgO + CaO + SrO + BaO is 12 to 30, SrO / CaO is 0.33 to 0.85, and (23.5 x [SiO ₂ ] + 3.5 x [Al ₂ O ₃ ] Alkali free glass having a [B ₂ O ₃ ] / (2.1 x [MgO] + 4.2 x [CaO] + 10 x [SrO] + 12 x [BaO]) of 17 or more. The method according to claim 1,
Alkali-free glass having a SrO / (MgO + CaO) of 0.05 to 4.0. 3. The method according to claim 1 or 2,
Non-alkali glass with Young's modulus of 78 ㎬ or more. 4. The method according to any one of claims 1 to 3,
Alkali-free glass having a photoelastic constant of 31 nm / MPa / cm or less. 5. The method according to any one of claims 1 to 4,
Alkali-free glass having a heat shrinkage of 200 ppm or less.