KR102229428B1 - Alkali-free glass - Google Patents

Abstract

The present invention relates to an alkali-free glass that has a low compaction and a small average coefficient of thermal expansion at 50°C to 350°C, and is easy to float molding, specifically, the compaction C1 is 5 ppm or less and the compaction C2 is 40 ppm or less, _{In an alkali-free glass containing SiO 2} 64 to 72, Al ₂ O ₃ 17 to 22, MgO 1 to 8, CaO 4 to 15.5, 0.20≦MgO/(MgO+CaO)≦0.41 in terms of oxide-based mass% About.

Description

Alkali-free glass {ALKALI-FREE GLASS}

The present invention is suitable as a substrate glass for a display or a substrate glass for a photomask used in the manufacture of various flat panel displays (FPDs). About.

BACKGROUND ART Conventionally, in forming a metal or oxide thin film on the surface of various substrate glass for displays, in particular, the following properties as disclosed in Patent Document 1 have been demanded.

(1) If an alkali metal oxide is contained, the alkali metal ions diffuse into the thin film and deteriorate the film properties. Therefore, the alkali metal ions should not be substantially contained.

(2) It must have sufficient chemical durability against various chemicals used for semiconductor formation. In particular, _{buffered hydrofluoric acid (BHF: mixture of hydrofluoric acid and ammonium fluoride) for etching SiO x} or SiN _x , chemicals containing hydrochloric acid used for etching ITO, various acids used for etching metal electrodes (nitric acid, sulfuric acid, etc.) ), the resist stripping solution should be durable against alkali.

(3) There should be no defects (bubbles, streaks, inclusions, pits, scratches, etc.) inside and on the surface.

In addition to the above demands, in recent years, the situation has been as follows.

(4) It is required to reduce the weight of the display, and the glass itself is also required to have a small density.

(5) It is required to reduce the weight of the display and to reduce the thickness of the substrate glass.

(6) In addition to the conventional amorphous silicon (a-Si) type liquid crystal display, a polycrystalline silicon (p-Si) type liquid crystal display with a slightly higher heat treatment temperature has been produced (a-Si: about 350°C → p- Si: 350 to 550°C).

(7) In order to increase productivity or increase thermal shock resistance by accelerating the heating and cooling rate of heat treatment when manufacturing a liquid crystal display, a glass with a small average coefficient of thermal expansion of the glass is required.

Japanese Patent Application Publication No. 2001-348247

In addition to the characteristics described in the background art, in recent years, when exposed to high temperatures in the thin film forming process, in order to minimize the deformation of the glass and the dimensional change accompanying the stabilization of the structure of the glass, it is required to have a low compaction of the glass.

It is an object of the present invention to provide an alkali-free glass that has a low compaction and a small average coefficient of thermal expansion, and is easy to form a float.

In the present invention, the compaction C1 is 5 ppm or less, the compaction C2 is 40 ppm or less, and is expressed in terms of mass% based on oxide.

SiO ₂ 64 to 72,

Al ₂ O ₃ 17 to 22,

MgO 1 to 8,

CaO 4 to 15.5

Contains,

It provides an alkali-free glass of 0.20≦MgO/(MgO+CaO)≦0.41.

In the alkali-free glass of the present invention,

Compaction C1 is 5ppm or less, compaction C2 is 25ppm or less, in terms of oxide-based mass%

SiO ₂ 67.5 to 72,

Al ₂ O ₃ 17 to 21,

MgO 1 to 6,

CaO 4 to 8.5

Contains,

SiO ₂ , Al ₂ O ₃ , MgO and CaO are 96% by mass or more in total,

It is preferable that 0.22≤MgO/(MgO+CaO)≤0.39.

In addition, in the alkali-free glass of the present invention, the compaction C1 is 5 ppm or less, the compaction C2 is 40 ppm or less, and is expressed in terms of mass% based on oxide.

SiO ₂ 64 to 68,

Al ₂ O ₃ 17 to 22,

MgO 2.3 to 8,

CaO 9 to 15.5

Contains,

SiO ₂ , Al ₂ O ₃ , MgO and CaO are 96% by mass or more in total,

It is preferable that 0.22≤MgO/(MgO+CaO)≤0.39.

The alkali-free glass of the present invention is suitable as a substrate glass for various displays or a substrate glass for a photomask, but can also be used as a glass substrate for magnetic disks or the like. However, due to its low compaction, various display substrate glass or photomask substrate glass that is required to minimize deformation of the glass and dimensional change accompanying the stabilization of the glass structure when exposed to high temperatures in the thin film formation process. Is valid as.

Next, the composition range of each component will be described. If SiO ₂ exceeds 72% (mass%, the same applies hereinafter, unless otherwise specified), there is a concern that the _{devitrification temperature T L will rise.} In addition, the viscosity is also increased, and there is a fear that the bubbles do not come out to the end during an increase in the melting temperature or clarification, and the bubbles may be mixed. If it is less than 64%, the ratio of the network forming agent decreases and the compaction increases. In addition, the average coefficient of thermal expansion increases.

Here, in the first aspect of the alkali-free glass of the present invention, the SiO ₂ content is 67.5% or more and 72% or less. If it exceeds 72%, the viscosity is also high, and there is a fear that the bubbles do not completely escape during the increase in the melting temperature or clarification, and the bubbles may be mixed. If it is less than 67.5%, there is a fear that the compaction will increase. 68% or more is more preferable.

In the second aspect of the alkali-free glass of the present invention, the SiO ₂ content is 64% or more and 68% or less. If it exceeds 68%, there is a fear that the melting temperature will rise. 67% or less is more preferable. If it is less than 64%, there is a fear that the compaction will increase. In addition, the average coefficient of thermal expansion increases.

When Al ₂ O ₃ exceeds 22%, there is a concern that the _{devitrification temperature T L may increase.} In addition _{, since it acts as a network-forming agent like SiO 2} , when it exceeds 22%, the viscosity increases, and there is a concern of an increase in the melting temperature and mixing of air bubbles. If it is less than 17%, an increase in compaction will be caused.

Here, in the first aspect of the alkali-free glass of the present invention, the Al ₂ O ₃ content is 17% or more and 21% or less. If it exceeds 21%, there exists a possibility that the _{devitrification temperature T L may rise.} 20.5% or less is more preferable. If it is less than 17%, an increase in compaction will be caused. 18% or more is more preferable.

In the second aspect of the alkali-free glass of the present invention, the Al ₂ O ₃ content is 17% or more and 22% or less. If it exceeds 22%, there exists a possibility that the _{devitrification temperature T L may rise.} 21% or less is more preferable. If it is less than 17%, an increase in compaction will be caused. 18% or more is more preferable.

When MgO exceeds 8%, the glass transition point Tg decreases. In addition, as the compaction increases, the average coefficient of thermal expansion increases. If it is less than 1%, the solubility deteriorates, the Young's modulus decreases, and the devitrification temperature T _L increases.

Here, in the first aspect of the alkali-free glass of the present invention, the MgO content is 1% or more and 6% or less. When it is more than 6%, the glass transition point Tg decreases, the compaction increases, and the average coefficient of thermal expansion increases. 5% or less is more preferable. If it is less than 1%, an increase in the _{devitrification temperature T L will be caused.} Also, the Young's modulus decreases. 2% or more is more preferable.

In the second aspect of the alkali-free glass of the present invention, the MgO content is 2.3% or more and 8% or less. If it exceeds 8%, the compaction increases and the average coefficient of thermal expansion increases. If it is less than 2.3%, an increase in the devitrification temperature TL will be caused. Also, the Young's modulus decreases. 4% or more is more preferable.

When CaO exceeds 15.5%, an increase in the compaction and an increase in the devitrification temperature T _L will be caused. If it is less than 4%, the solubility deteriorates, the melting temperature rises, and the devitrification temperature also rises.

Here, in the first aspect of the alkali-free glass of the present invention, the CaO content is 4% or more and 8.5% or less. If it exceeds 8.5%, an increase in the compaction and an increase in the devitrification temperature T _L will be caused. If it is less than 4%, the solubility deteriorates, the melting temperature rises, and the devitrification temperature also rises. 5% or more is more preferable.

In the second aspect of the alkali-free glass of the present invention, the CaO content is 9% or more and 15.5% or less. If it exceeds 15.5%, an increase in the compaction and an increase in the devitrification temperature T _L will be caused. If it is less than 9%, the solubility deteriorates and the melting temperature rises. 10% or more is more preferable.

When MgO/(CaO+MgO) is higher than 0.41, the compaction when heat-treated at 600°C increases. In addition, the average coefficient of thermal expansion increases. 0.39 or less is preferable and 0.37 or less is more preferable. If it is lower than 0.20, the devitrification temperature T _L rises. 0.22 or more is preferable and 0.24 or more is more preferable.

Other components, such as the following components, may be contained within a range that does not impair the effects of the present invention. The other components in this case are preferably less than 5%, more preferably less than 4%, more preferably less than 3%, even more preferably less than 1%, even more preferably in order to achieve both high Young's modulus and low compaction. It is preferably less than 0.5%, particularly preferably substantially, ie not containing inevitable impurities except for inevitable impurities. Therefore, in the present invention, _{the total content of SiO 2} , Al ₂ O ₃ , CaO and MgO is preferably 95% or more, more preferably 96% or more, more preferably 97% or more, and even more preferably 99% or more. It is even more preferable that it is 99.5% or more. It is particularly preferred to include _{SiO 2} , Al ₂ O ₃ , CaO and MgO substantially, ie, excluding unavoidable impurities.

B ₂ O ₃ may be contained in order to improve the dissolution reactivity of the glass. However, if it is too large, the Young's modulus decreases and the compaction increases, so the content is preferably less than 3%, more preferably less than 1%, and particularly preferably substantially not contained.

BaO may be contained in order to improve the solubility of the glass. However, if too much, the average coefficient of thermal expansion increases, so the content is preferably less than 5%, more preferably less than 3%, even more preferably less than 1%, even more preferably less than 0.5%, and does not contain substantially It is particularly preferred.

SrO may be contained to improve solubility. However, if too much, the average coefficient of thermal expansion increases, so the content is preferably less than 5%.

Here, in the first aspect of the alkali-free glass of the present invention, the content of SrO is preferably less than 3%, more preferably less than 1%, even more preferably less than 0.5%, and particularly preferably not substantially contained. .

In the second aspect of the alkali-free glass of the present invention, the content of SrO is preferably less than 2%, more preferably less than 1%, more preferably less than 0.3%, and particularly preferably not substantially contained.

ZrO ₂ may be contained in order to improve the Young's modulus of the glass. However, if too much, the devitrification temperature rises, so the content is preferably less than 3%, more preferably less than 1%, and particularly preferably not substantially contained.

In addition, in the present invention, in order to improve the solubility, clarity and moldability of glass, the glass raw material contains ZnO, SO ₃ , Fe ₂ O ₃ , F, Cl, SnO ₂ in total amount less than 1%, preferably less than 0.5% , More preferably, it may contain less than 0.3%, and even more preferably less than 0.1%.

Further, the glass of the present invention does not contain an alkali metal oxide exceeding the impurity level (ie, substantially) in order not to cause deterioration in properties of the metal or oxide thin film formed on the glass surface during panel manufacturing. In addition, in order to facilitate recycling of the glass, _{it is preferable that PbO, As 2} O ₃ and Sb ₂ O ₃ are not substantially contained.

The alkali-free glass of the present invention has an extremely low compaction.

The compaction is a glass heat shrinkage rate generated by relaxation of the glass structure at the time of heat treatment. In the present invention, the compaction means a value measured by the method described below.

First, after dissolving the target glass at 1550°C to 1650°C, the molten glass is poured out, molded into a plate shape, and then cooled. The obtained plate glass is polished to obtain a 100 mm×20 mm×1 mm glass plate.

Next, the obtained glass plate is heated to the glass transition point Tg+70°C, maintained at this temperature for 1 minute, and then cooled to room temperature at a temperature-fall rate of 40°C/minute. After that, two indentations are formed on the surface of the glass plate in the direction of the long side, at intervals A (A = 90 mm), and a sample before treatment is obtained.

Next, the sample before treatment is heated to 450°C at a temperature increase rate of 100°C/hour, maintained at 450°C for 2 hours, and then cooled to room temperature at a temperature decrease rate of 100°C/hour to obtain sample 1 after treatment.

Then, after treatment, the distance B1 between the indentations of Sample 1 was measured.

From A and B1 thus obtained, compaction C1 is calculated using the following formula.

C1[ppm]=(A-B1)/A×10 ⁶

In addition, the sample before treatment is heated to 600°C at a temperature increase rate of 100°C/hour, maintained at 600°C for 1 hour, and then cooled to room temperature at a temperature decrease rate of 100°C/hour to obtain sample 2 after treatment.

Then, after treatment, the distance B2 between the indentations of Sample 2 was measured.

From A and B2 thus obtained, compaction C2 is calculated using the following equation.

C2[ppm]=(A-B2)/A×10 ⁶

The alkali-free glass of the present invention has a compaction C1 of 5 ppm or less. On the other hand, the compaction C2 is 40 ppm or less.

Since the alkali-free glass of the present invention satisfies the above conditions, the compactions C1 and C2 satisfy the above conditions, so when exposed to high temperatures in a thin film forming process performed in the process of manufacturing various displays using an alkali-free glass, glass deformation and glass The dimensional change accompanying the stabilization of the structure can be suppressed to a minimum.

Here, in the first aspect of the alkali-free glass of the present invention, the compaction C1 is 5 ppm or less. On the other hand, the compaction C2 is 25 ppm or less, and 20 ppm or less is more preferable.

In the second aspect of the alkali-free glass of the present invention, the compaction C1 is 5 ppm or less. On the other hand, the compaction C2 is 40 ppm or less, and 35 ppm or less is more preferable.

In addition, in order to facilitate dissolution of the alkali-free glass of the present invention and to suppress erosion of the refractory bricks constituting the melting kiln _{, the temperature T 2} ^{at which the viscosity η is 10 2} poise (dPa·s) is 1760. It is preferably at most °C.

Here, in the first aspect of the alkali-free glass of the present invention, _{it is preferable that T 2} is 1760°C or less. 1740°C is more preferable, and 1720°C or less is even more preferable.

In the second aspect of the alkali-free glass of the present invention, _{it is preferable that T 2} is 1730°C or less. 1710°C or less is more preferable, and 1690°C or less is even more preferable.

In addition, the alkali-free glass of the present invention _{preferably has a temperature T 4} of 1380°C or less ^{at which the viscosity η is 10 4} poise (dPa·s) in order to facilitate float molding.

Here, in the first aspect of the alkali-free glass of the present invention, _{it is preferable that T 4} is 1380°C or less. 1360°C is more preferable, and 1340°C or less is even more preferable.

In the second aspect of the alkali-free glass of the present invention, _{it is preferable that T 4} is 1360°C or less. 1340°C or less is more preferable, and 1320°C or less is even more preferable.

In addition, the alkali-free glass of the present invention preferably has an average coefficient of thermal expansion at 50 to 350°C of 40×10 ^-7 /°C or less in order to increase thermal shock resistance and increase productivity during panel manufacturing.

Here, in the first aspect of the alkali-free glass of the present invention, the average coefficient of thermal expansion at 50 to 350° ^{C is preferably 37×10 -7} /°C or ^{less, and more preferably 34×10 -7} /°C or less.

In the second aspect of the alkali-free glass of the present invention, the average coefficient of thermal expansion at 50 to 350° ^{C is preferably 40×10 -7} /°C or ^{less, and more preferably 38×10 -7} /°C or less.

The alkali-free glass of the present invention preferably has a glass transition point of 780° C. or higher in order to suppress heat shrinkage during panel manufacturing and to enable a method by laser annealing as a method for manufacturing a p-Si TFT.

If the glass transition point is 780°C or higher, the virtual temperature of the glass is likely to rise in the manufacturing process (for example, a plate thickness of 0.7 mm or less, preferably 0.5 mm or less, more preferably 0.3 mm or less of organic EL, etc. It is suitable for a display substrate or a lighting substrate, or a thin-plate display substrate or lighting substrate having a plate thickness of 0.3 mm or less, preferably 0.1 mm or less).

In the molding of plate glass with a 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 withdrawal speed at the time of molding tends to increase. It is easy to increase. In this case, the compaction can be suppressed if it is glass of a high-strength transition point.

The alkali-free glass of the present invention can be produced, for example, by the following method. The raw materials of each component that are usually used are combined so as to become a target component, which is continuously added to a melting furnace, and heated to 1550 to 1650°C to melt. A plate glass can be obtained by forming this molten glass to a predetermined plate thickness by a float method and cutting it after slow cooling.

Example

In the following, Examples 1 to 12 are Examples, and Examples 13 to 15 are Comparative Examples. The raw materials of each component were combined so as to obtain a target composition, and dissolved at a temperature of 1550 to 1650°C using a platinum crucible. In dissolution, the glass was homogenized by stirring using a platinum stirrer. Subsequently, the molten glass was poured out, formed into a plate, and then slowly cooled.

In Tables 1 to 2, glass composition (unit: mass%), density ρ (g/cm 3 ), Young's modulus E (GPa) (measured by ultrasonic method), and inelastic modulus E/ρ (GPa·cm 3 /g) , Glass transition point Tg (unit: °C), average coefficient of thermal expansion α (unit: ×10 ^-7 / °C) at 50 to 350 °C, temperature T ₂ at which glass viscosity η becomes 10 ² poise (unit: °C) , The glass viscosity η represents the temperature T ₄ ^{(unit:° C.) at which the glass viscosity η becomes 10 4} poise, and compactions C1 and C2 (measured by the above-described method, unit: ppm).

In addition, in Tables 1 to 2, values shown in parentheses are calculated values.

As found from the table, the glasses of the examples have a compaction C1 of 5 ppm or less and a compaction C2 of 40 ppm or less. In addition, the average coefficient of thermal expansion at 50 to 350°C is 40×10 ^-7 /°C or less.

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

This application is based on Japanese Patent Application No. 2013-134900 for which it applied on June 27, 2013, The content is taken in in this specification as a reference.

The alkali-free glass of the present invention is suitable as a substrate glass for various displays or a substrate glass for a photomask, but can also be used as a glass substrate for magnetic disks or the like. However, due to its low compaction, various display substrate glass or photomask substrate glass that is required to minimize deformation of the glass and dimensional change accompanying the stabilization of the glass structure when exposed to high temperatures in the thin film formation process. Is valid as.

Claims (3)

Compaction C1 is 5ppm or less, compaction C2 is 40ppm or less, in terms of oxide-based mass%
SiO ₂ 64 to 72,
Al ₂ O ₃ 18 to 22,
MgO 1 to 8,
CaO 4 to 15.5
Contains,
SiO ₂ , Al ₂ O ₃ , MgO and CaO are 96% by mass or more in total,
Alkali-free glass with 0.20≤MgO/(MgO+CaO)≤0.41.
Here, the compaction represents the glass heat contraction rate generated by relaxation of the glass structure during heat treatment, and the compactions C1 and C2 are measured by the following method.
① After dissolving the glass at 1550°C to 1650°C, the molten glass is poured out, molded into a plate, and then cooled. The obtained plate glass is polished to obtain a 100 mm×20 mm×1 mm glass plate.
(2) The obtained glass plate is _{heated to a glass transition point T g} +70°C, maintained at this temperature for 1 minute, and then cooled to room temperature at a temperature-fall rate of 40°C/minute. After that, two indentations are formed on the surface of the glass plate in the direction of the long side, at intervals A (A = 90 mm), and a sample before treatment is obtained.
③ Before treatment, heat the sample to 450°C at a heating rate of 100°C/hour, hold at 450°C for 2 hours, cool it to room temperature at a temperature decrease rate of 100°C/hour, and use as sample 1 after treatment. After treatment, measure the distance B1 between the indentations of Sample 1.
④ From A and B1, compaction 1 is calculated using the following equation.
C1[ppm]=(A-B1)/AХ10 ⁶
⑤ Before treatment, heat the sample to 600°C at a temperature increase rate of 100°C/hour, hold at 600°C for 1 hour, cool to room temperature at a temperature decrease rate of 100°C/hour, and use as sample 2 after treatment. After treatment, measure the distance B2 between the indentations of Sample 2.
⑥ From A and B2 above, compaction 2 is calculated using the following equation.
C2[ppm]=(A-B2)/AХ10 ⁶ The method of claim 1,
Compaction C1 is 5ppm or less, compaction C2 is 25ppm or less, in terms of oxide-based mass%
SiO ₂ 67.5 to 72,
Al ₂ O ₃ 18 to 21,
MgO 1 to 6,
CaO 4 to 8.5
Contains,
SiO ₂ , Al ₂ O ₃ , MgO and CaO are 96% by mass or more in total,
Alkali-free glass with 0.22≤MgO/(MgO+CaO)≤0.39. The method of claim 1,
Compaction C1 is 5ppm or less, compaction C2 is 40ppm or less, in terms of oxide-based mass%
SiO ₂ 64 to 68,
Al ₂ O ₃ 18 to 22,
MgO 2.3 to 8,
CaO 9 to 15.5
Contains,
SiO ₂ , Al ₂ O ₃ , MgO and CaO are 96% by mass or more in total,
Alkali-free glass with 0.22≤MgO/(MgO+CaO)≤0.39.