JP2009274902A - Glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide glass having low thermal expansion, a low glass transition point and low-temperature melting property, having an average coefficient of linear expansion, at temperature of 0°C to 300°C, preferably of not more than 50×10<SP>-7</SP>°C<SP>-1</SP>, more preferably 45×10<SP>-7</SP>°C<SP>-1</SP>, and most preferably 42×10<SP>-7</SP>°C<SP>-1</SP>, and having a glass transition point of preferably not higher than 650°C, more preferably not higher than 600°C, and most preferably not higher than 580°C. <P>SOLUTION: The glass has an average coefficient of linear expansion, at temperature of 0°C to 300°C, of not more than 50×10<SP>-7</SP>°C<SP>-1</SP>and a glass transition point of not higher than 650°C and contains an SiO<SB>2</SB>component, a B<SB>2</SB>O<SB>3</SB>component and a ZnO component, in terms of oxides, with the total content of these components of not less than 75% and a ratio ZnO/(SiO<SB>2</SB>+B<SB>2</SB>O<SB>3</SB>) of not less than 0.08 of these components by mass%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a glass having a low average linear expansion coefficient and a low glass transition point useful as various substrate materials.

  Glass having a low average linear expansion coefficient is used in a wide range of fields such as substrate materials and heat-resistant glass in the precision instrument field.

  In recent years, glass having a low glass transition point with a low average linear expansion coefficient and excellent hot workability has been demanded in applications such as for mirror substrates for telescopes. Furthermore, these glasses are required to be manufactured at a low cost, and must be meltable at a low temperature.

Borosilicate glass is commonly known as a low thermal expansion glass. A typical example is Corning # 7740, which has an average linear expansion coefficient of 32.5 × 10 ⁻⁷ ° C ⁻¹ at 0 to 300 ° C. and a glass transition point of 530 ° C., but has a melting temperature of It is a very high temperature of 1500 ° C. or higher.
For this reason, in the production of such glass, it has been difficult to clarify the glass, and the internal quality of the molded glass tends to be deteriorated, and the cost of the production equipment is increased.

  Further, since glass having a low average linear expansion coefficient as disclosed in Patent Documents 1 and 2 is mainly used as a heat-resistant glass, it is required to have a high glass transition point, low thermal expansion, low temperature melting No glass is disclosed that combines the properties and low glass transition point.

JP 2005-139031 A JP 2000-44278 A

The object of the present invention is to have a low thermal expansion property and a low glass transition point, can be melted at a relatively low temperature, and preferably has an average linear expansion coefficient at 0 ° C. to 300 ° C. of 50 × 10 ⁻⁷ ° C. ^−1. Or less, more preferably 45 × 10 ⁻⁷ ° C.− ¹ or less, most preferably 40 × 10 ⁻⁷ ° C.− ¹ or less, and the glass transition point is preferably 650 ° C. or less, more preferably 600 ° C. or less, most preferably It is to provide a glass that is 580 ° C. or lower.

The melting temperature of the glass raw material (also simply referred to as the melting temperature) is an index of low-temperature melting property, and when the raw material is heated to form a melt, the temperature at which the viscosity becomes 10 ^2.5 dPa · s. Say. The measurement can be performed using a ball pulling-up type viscometer, for example, using BVM-13LH manufactured by Opto Corporation.
The average linear expansion coefficient is an indicator of low thermal expansion, and the temperature range is 0 ° C. according to JOGIS (Japan Optical Glass Industry Association Standard) 16-2003 “Measurement Method of Average Linear Expansion Coefficient of Optical Glass Near Room Temperature”. To 50 ° C, and values measured in the range of 0 ° C to 300 ° C.
The glass transition point can be used as an index of hot workability, and is a value measured by JOGIS (Japan Optical Glass Industry Association Standard) 08-2003 “Measurement Method of Thermal Expansion of Optical Glass”. The lower this value is, the lower the temperature of the glass can be deformed, and the better the hot workability of the glass.

In order to solve the above problems, the present inventor contains SiO ₂ component, B ₂ O ₃ component, and ZnO component on the basis of oxide, and the total amount of these components is 75% or more, and the mass% of these components Glass having a ratio of ZnO / (SiO ₂ + B ₂ O ₃ ) of 0.08 or more has an average linear expansion coefficient at 0 ° C. to 50 ° C. of 50 × 10 ⁻⁷ ° C.− ¹ or less, more preferably 45 × 10 ⁻⁷ ° C. ⁻¹ or less, most preferably 42 × 10 ⁻⁷ ° C. ⁻¹ or less, and the glass transition point is preferably 650 ° C. or less, more preferably 600 ° C. or less, and most preferably 580 ° C. or less. It has been found that melting is possible at a relatively low temperature of 1500 ° C. or lower. More specifically, the present invention provides the following.

(Configuration 1)
It contains SiO ₂ component, B ₂ O ₃ component, and ZnO component in mass% based on oxide, and the total amount of these components is 75% or more, and the ratio of these components in mass% ZnO / (SiO ₂ + B ₂ O ₃ ) is 0.08 or more, the average linear expansion coefficient at 0 to 300 ° C. is 20 × 10 ⁻⁷ ° C. ⁻¹ to 50 × 10 ⁻⁷ ° C.− ¹ , and the glass transition point is 650 ° C. or less. Some glass.
(Configuration 2)
The glass according to Configuration 1, wherein the content of the ZnO component is 5% to 20% by mass% based on the oxide.
(Configuration 3)
The composition according to configuration 1 or 2, comprising an Al ₂ O ₃ component, wherein the total amount of the SiO ₂ component, the B ₂ O ₃ component, the Al ₂ O ₃ component, and the ZnO component is 90% or more by mass% based on the oxide. Glass.
(Configuration 4)
% By mass based on oxide,
50 to 60% of SiO ₂ component,
15-22% of B ₂ O ₃ component,
Al ₂ O ₃ component 8-15%
The glass in any one of the structures 1-3 to contain.
(Configuration 5)
% By mass based on oxide,
0 to 2% of Li ₂ O component and / or 0 to 5% of Na ₂ O component
The glass in any one of the structures 1-4 contained.
(Configuration 6)
% By mass on the oxide basis, the glass according to any of the 1-5 total amount of Na ₂ O component and Li ₂ O component is not more than 5%.
(Configuration 7)
% By mass based on oxide,
MgO component 0-2%, and / or SrO component 0-2%, and / or BaO component 0-2%, and / or SnO component 0-2%
The glass in any one of the structures 1-6 to contain.
(Configuration 8)
Glass according to any of the 1 to 7, containing 0 to 1% of _As 2 _{O 3} component and / or _Sb 2 _{O 3} component in weight percent on the oxide basis.
(Configuration 9)
The glass according to any one of claims 1 to 8, wherein the temperature when the viscosity is 10 ^2.5 dPa · s is 1500 ° C or lower.

In the present invention, since the component composition is expressed by mass%, it should not be expressed directly. However, in order to achieve the same effect as the above configuration, the molar ratio is generally within the following range.
(Configuration 10)
The glass according to configuration 1, wherein the content of the ZnO component is 4% to 15% in terms of mol% based on oxide.
(Configuration 11)
In mole percent on oxide basis,
SiO ₂ component 57-68%,
14 to 21% of B ₂ O ₃ component,
Al ₂ O ₃ component 4-11%
The glass of the structure 10 to contain.
(Configuration 12)
In mole percent on oxide basis,
0 to 2% of Li ₂ O component and / or 0 to 5% of Na ₂ O component
The glass of the structure 10 or 11 to contain.
(Configuration 13)
In mole percent on the oxide basis, the glass according to any of the 10 to 12 the total amount of Na ₂ O component and Li ₂ O component is not more than 5%.
(Configuration 13)
In mole percent on oxide basis,
MgO component 0-4%, and / or SrO component 0-2%, and / or BaO component 0-2%, and / or SnO component 0-2%
The glass in any one of the structures 10-12 to contain.
(Configuration 14)
Glass according to any of the 10 to 13 containing 0 to 0.5% of _As 2 _{O 3} component and / or _Sb 2 _{O 3} component in mole percent on the oxide basis.

According to the present invention, it is possible to provide a glass having a low thermal expansion property and a low glass transition point, and also having a low temperature melting property as a more preferable characteristic. That is, the average linear expansion coefficient at 0 ° C. to 300 ° C. is preferably 50 × 10 ⁻⁷ ° C.− ¹ or less, more preferably 45 × 10 ⁻⁷ ° C.− ¹ or less, and most preferably 42 × 10 ⁻⁷ ° C.− ¹ or less. The glass transition point is preferably 650 ° C. or lower, more preferably 600 ° C. or lower, most preferably 580 ° C. or lower. The melting temperature of the glass raw material (viscosity when the raw material is heated to form a melt is 10 ^2.5. A glass having a temperature (dPa · s) of preferably 1500 ° C. or lower, more preferably 1490 ° C. or lower, and most preferably 1480 ° C. or lower can be provided.
The glass of the present invention is suitable as various substrate materials, structural members, transmission optical system materials and the like that require thermal dimensional stability and hot workability.

The average linear expansion coefficient of the glass of the present invention can be preferably applied as various substrate materials, structural members, or transmission optical system materials that require thermal dimensional stability. ⁻⁷ ° C. ⁻¹ or less is preferable, 45 × 10 ⁻⁷ ° C. ⁻¹ or less is more preferable, and 42 × 10 ⁻⁷ ° C. ⁻¹ or less is most preferable. Moreover, although the lower limit of the average linear expansion coefficient in 0 degreeC-300 degreeC is so preferable that it is low, in the glass of this invention, it is possible to obtain to ^20x10 <^{-7> degreeC- 1} .
The glass transition point is preferably 650 ° C. or less, more preferably 600 ° C. or less, and most preferably 580 ° C. or less, because it can be preferably applied as various substrate materials, structural members and the like that require hot working. Moreover, although a glass transition point is so preferable that it is low, in the glass of this invention, it can show a low value to 500 degreeC.
The melting temperature of the glass raw material is preferably 1500 ° C. or less, more preferably 1490 ° C. or less, and most preferably 1480 ° C. or less in order to reduce the cost of glass production and facilitate glass refining. The melting temperature of the glass of the present invention can be as low as about 1450 ° C.

Each component which comprises the glass of this invention is demonstrated. Note that unless otherwise specified, in the present specification, the respective components are expressed in terms of mass% based on oxides.
Here, the “oxide standard” is contained in the glass on the assumption that oxides, nitrates, etc. used as raw materials of the constituent components of the glass of the present invention are all decomposed and changed into oxides when melted. This is a method of expressing the composition of each component, and the amount of each component contained in the glass is described with the total mass of the generated oxides being 100% by mass.

The glass of the present invention contains a SiO ₂ component, a B ₂ O ₃ component, and a ZnO component on an oxide basis, and the total amount of these components is 75% or more, and the ratio of these components in mass% ZnO / (SiO ₂ + B ₂ O ₃ ) is 0.08 or more.
The SiO ₂ component and the B ₂ O ₃ component are components that form the glass skeleton of the present invention.
The SiO ₂ component is an essential component for obtaining a low average linear expansion coefficient, but tends to increase the melting temperature of the glass.
The B ₂ O ₃ component lowers the viscosity in the high temperature region and improves the low temperature melting property (can be melted at a lower temperature), but on the other hand, the glass tends to be phase-separated.
Further, the ZnO component has the effect of improving the low-temperature meltability and lowering the glass transition point, while it tends to increase the average coefficient of linear expansion of the glass.
As described above, these components have an effect contrary to the effect of contributing to the desired physical properties, and the present invention sets the total amount of these SiO ₂ component, B ₂ O ₃ component, and ZnO component in a specific range, and also oxidizes. By making the ZnO / (SiO ₂ + B ₂ O ₃ ) ratio in mass% in terms of physical properties within a specific range, the effect of obtaining the desired physical properties can be minimized by minimizing the influence of the effects contrary to the desired physical properties. It is possible to obtain a glass having an average linear expansion coefficient at 0 to 300 ° C. of 50 × 10 ⁻⁷ ° C. ⁻¹ or less and a glass transition point of 650 ° C. or less while maintaining a low melting temperature. It is what.

If the total amount of the SiO ₂ component, the B ₂ O ₃ component, and the ZnO component is less than 75%, the above-described effects of contributing to the desired physical properties cannot be sufficiently obtained. The lower limit of the total amount is preferably 75% or more, more preferably 78% or more, and most preferably 80% or more.

If the ZnO / (SiO ₂ + B ₂ O ₃ ) ratio is less than 0.08, the low-temperature meltability is impaired. Therefore, the ratio is preferably 0.08 or more, and more preferably 0.09 or more. Preferably, it is most preferably 0.10 or more.
Further, if the ratio exceeds 0.20, the tendency to devitrification is increased and the stability as glass is remarkably impaired. Therefore, the ratio is preferably 0.20 or less, more preferably 0.19 or less. Preferably, it is 0.18 or less.

If the content of the SiO ₂ component is less than 50%, it is difficult to obtain a desired average linear expansion coefficient. Therefore, the lower limit of the content of the SiO ₂ component is preferably 50% or more, and more preferably 52% or more. More preferably, it is most preferable to set it as 53% or more.
Further, in order to lower the melting temperature of the glass of the present invention and improve the low temperature melting property, the upper limit of the content of the SiO ₂ component is preferably 60% or less, and 59% or less. Is more preferable, and most preferably 58% or less.

When the content of the B ₂ O ₃ component is less than 15%, melting of the glass raw material tends to be difficult, so the lower limit of the content of the B ₂ O ₃ component is preferably 15% or more. It is more preferably 5% or more, and most preferably 16% or more.
Further, if the content of the B ₂ O ₃ component exceeds 22%, the average linear expansion coefficient of the glass increases and the phase separation tendency increases. Therefore, the upper limit of the content of the B ₂ O ₃ component is 22%. The content is preferably set to be 21% or less, more preferably 21% or less, and most preferably 20.5% or less.

If the content of the ZnO component is less than 5%, low temperature melting of the glass raw material tends to be difficult, so the lower limit of the content of the ZnO component is preferably 5% or more, and preferably 7% or more. More preferably, it is most preferably 9% or more.
When the content of the ZnO component exceeds 20%, the average linear expansion coefficient tends to increase and the devitrification tendency tends to increase. Therefore, the content is preferably 20% or less, more preferably 16% or less, 13 % Or less is most preferable.

The Al ₂ O ₃ component is a component that can form the glass skeleton of the present invention and suppresses phase separation. When the total amount of the Al ₂ O ₃ component, the SiO ₂ component, the B ₂ O ₃ component, and the ZnO component is less than 90%, it becomes difficult to obtain a glass having a desired thermal expansion coefficient. It is preferable to set it as the above, and it is most preferable to set it as 92% or more.
If the Al ₂ O ₃ component is less than 8%, the coefficient of thermal expansion tends to increase and the tendency of phase separation of the glass increases, so it is preferably 8% or more, and more preferably 9% or more. Most preferred. Further, if it exceeds 15%, the solubility is remarkably lowered and it becomes difficult to obtain a glass having a desired glass transition point. Therefore, it is preferably 15% or less, and most preferably 13% or less.

The Li ₂ O component is a component that can be optionally added to easily lower the glass transition point and improve the meltability. However, since the coefficient of thermal expansion tends to increase as the content increases, the upper limit of the content is preferably 2% or less, and most preferably 1% or less.

The Na ₂ O component is a component that can be optionally added to easily lower the glass transition point and improve the meltability. However, since the coefficient of thermal expansion tends to increase as the content increases, the upper limit of the content is preferably 5% or less, and most preferably 4% or less.

Further, if the total amount of the Li ₂ O component and the Na ₂ O component exceeds 5%, it becomes difficult to obtain a glass having a desired thermal expansion coefficient. Therefore, the total amount is preferably 5% or less, and 4.5% or less. Is more preferable, and 4% or less is most preferable.

  The MgO component is a component that can be optionally added to facilitate improving the low-temperature meltability. However, as the content increases, the glass transition point increases and devitrification increases. Therefore, the upper limit of the content is preferably 2% or less, and most preferably 1.5% or less.

The SrO component is a component that can be optionally added to easily improve the low-temperature meltability. However, since the average linear expansion coefficient tends to increase when the amount added is large, the upper limit of the content is preferably 2% or less, and most preferably 1% or less.

  The BaO component is a component that can be optionally added to easily suppress the phase separation of the glass and to improve the low-temperature meltability. However, since the average linear expansion coefficient tends to increase when the amount added is large, the upper limit of the content is preferably 2% or less, and most preferably 1.5% or less.

The SnO component is a component that can be optionally added so that the low temperature meltability can be easily improved and a clarifying effect can be expected. However, since the average linear expansion coefficient tends to increase when the amount added is large, the upper limit of the content is preferably 2% or less, and most preferably 1% or less.

As ₂ O ₃ component and Sb ₂ O ₃ component are components that can be optionally added as a glass refining agent. However, even if added in a large amount, the clarification effect does not increase, so 1% is the upper limit, preferably 0.5% or less, and most preferably 0.3% or less.

  Since the PbO component requires measures for environmental measures when manufacturing, processing, and discarding the glass, and costs are required for this, PbO should not be contained in the glass of the present invention.

Furthermore, in the glass of the present invention, each component such as V, Cr, Mn, Fe, Co, Ni, Mo, Eu, Nd, Sm, Tb, Dy, and Er contributes little to the object of the present invention. In consideration of use as a transmission optical system material because it is colored, it is preferably not contained.
However, the term “not contained” means that it is not contained artificially unless it is mixed as an impurity.

Other components may be added as long as they do not impair the gist of the present invention, but in order to easily obtain a small average linear expansion coefficient, SiO ₂ component, Al ₂ O ₃ component, B ₂ O ₃ It is preferable that each component contained in the glass other than the component and the ZnO component does not exceed 5% in terms of mass% based on the oxide.

As a method for producing the glass of the present invention, a known melting method can be used. That is, silica sand, boric acid, aluminum oxide, zinc white, lithium carbonate, sodium carbonate, magnesium oxide, strontium nitrate, barium nitrate, arsenous acid, antimony pentoxide so that the glass of the present invention has a composition expressed on an oxide basis. A glass raw material made of etc. is filled into a crucible made of quartz or platinum. And it heat-melts in melting furnaces, such as an electric furnace and a gas furnace. In the glass of the present invention, the melting temperature of the glass raw material is 1500 ° C. or less, the temperature at the time of heating and melting in the melting furnace is 1450 ° C. to 1500 ° C., and in a preferred embodiment, the glass raw material can be melted at a temperature of 1400 ° C. to 1450 ° C. it can.
After melting, clarification and stirring are performed as necessary to homogenize the glass, and then the molten glass is poured into a mold and rapidly cooled to form and slowly cool in a slow cooling furnace.

  The glass taken out from the slow cooling furnace can be cut, ground, and polished as necessary to obtain various substrate materials, structural members, and transmission optical system materials.

  Examples of the present invention will be described. It consists of silica sand, boric acid, aluminum oxide, zinc white, lithium carbonate, sodium carbonate, magnesium oxide, strontium nitrate, barium nitrate and antimony pentoxide so that the glass has the composition ratio shown on the oxide basis as shown in Table 1. A glass raw material batch was prepared. The batch was filled in a platinum crucible and heated and melted in an electric furnace at 1400 to 1500 ° C. for 6 hours. The molten glass was molded into a plate shape and slowly cooled.

Table 1 shows the glass composition, melting temperature, average linear expansion coefficient (α) at 0 ° C. to 50 ° C. and average linear expansion coefficient at 0 ° C. to 300 ° C. (Α) indicates the temperature when the viscosity of the glass is 10 ^2.5 dPa · s.
Moreover, the temperature-viscosity graph of Example 7 of this invention and the glass (Corning company # 7740) of a comparative example is shown in FIG.

All the glasses of the above examples have an average linear expansion coefficient of 42 × 10 ⁻⁷ ° C.− ¹ or less at 0 ° C. to 300 ° C., a temperature when the viscosity is 10 ^2.5 dPa · s, 1500 ° C. or less, and glass The transition point is 580 ° C. or lower.

  These glasses were sequentially processed by cutting, grinding, and polishing to prepare a substrate material, a structural member, and a transmission optical material. All of these have thermal dimensional stability, and can be manufactured at a lower cost than the conventional heat-low expansion glass and ceramic materials, and can be easily processed.

  Moreover, the glass produced in the said Example was able to carry out self weight deformation | transformation at the comparatively low temperature of 750 to 850 degreeC. Therefore, by using the glass of the present invention, it is possible to easily obtain a large block product which is usually difficult to mold by deforming the elongated rod-shaped glass material by heating in a mold.

It is a temperature-viscosity graph of Example 7 of this invention and a comparative example (Corning company # 7740), a vertical axis | shaft is the value of logarithmic log (eta) of a viscosity (dPa * s), and a horizontal axis is temperature (degreeC).

Claims (9)

It contains SiO ₂ component, B ₂ O ₃ component, and ZnO component in mass% based on oxide, and the total amount of these components is 75% or more, and the ratio of these components in mass% ZnO / (SiO ₂ + B ₂ O ₃ ) is 0.08 or more, the average linear expansion coefficient at 0 to 300 ° C. is 20 × 10 ⁻⁷ ° C. ⁻¹ to 50 × 10 ⁻⁷ ° C.− ¹ , and the glass transition point is 650 ° C. or less. Some glass.   The glass according to claim 1, wherein the content of the ZnO component is 5% to 20% by mass% based on the oxide. The Al ₂ O ₃ component is contained, and the total amount of the SiO ₂ component, the B ₂ O ₃ component, the Al ₂ O ₃ component, and the ZnO component is 90% or more by mass% based on the oxide. Glass. % By mass based on oxide,
50 to 60% of SiO ₂ component,
15-22% of B ₂ O ₃ component,
Al ₂ O ₃ component 8-15%
The glass according to any one of claims 1 to 3. % By mass based on oxide,
0 to 2% of Li ₂ O component and / or 0 to 5% of Na ₂ O component
The glass according to any one of claims 1 to 4, which is contained. % By mass on the oxide basis, the glass according to any one of claims 1 to 5 the total amount of Na ₂ O component and Li ₂ O component is not more than 5%. % By mass based on oxide,
MgO component 0-2%, and / or SrO component 0-2%, and / or BaO component 0-2%, and / or SnO component 0-2%
The glass according to claim 1, which is contained. Glass according to claim 1 containing 0 to 1% of _As 2 _{O 3} component and / or _Sb 2 _{O 3} component in weight percent on the oxide basis. The glass according to any one of claims 1 to 8, wherein the temperature when the viscosity is 10 ^2.5 dPa · s is 1500 ° C or lower.