JPH08104539A - Transparent low-expanding crystallized glass - Google Patents

Abstract

PURPOSE: To produce a transparent low-expanding crystallized glass excellent in melting property and shapability, colorless and good in transparency, having coefficient of thermal expansion of zero or near it and good in heat resistance and flameproof and especially to produce a transparent low-expanding crystallized glass useful as a heat resistant and fire resistant window. CONSTITUTION: The crystallized glass is obtained by heat-treating and crystallizing a starting glass having compsn. containing 59-63wt.% SiO2 , 21-24wt.% Al2 O3 , 1-3wt.% MgO, 1-3wt.% ZnO, 4-5wt.% Li2 O, 1-3wt.% TiO2 , 1-4wt.% ZrO2 , 1-3wt.% P2 O5 , 0.5-2wt.% BaO and 0.5-2wt.% NaO2 and in which 0.5-2wt.% As2 O3 is externally added based on 100wt.% above composition, and when each molar fraction of Al2 O3 , Li2 O, MgO and ZnO is denoted as (a), (l), (m) and (zn) respectively, formula 0.9<=a/(l+m+zn)<=1.1 is satisfied. The crystallized glass is composed of the transparent low-expanding crystallized glass containing mainly β-quqrtz based crystal phase an having within 0±5×10<-7> / deg.C coefficient of thermal expansion.

Description

Detailed Description of the Invention

[0001]

Industrial Field of the Invention The present invention is a crystallized glass that is colorless and transparent, has excellent heat resistance and fire resistance, is easy to melt and crystallize, and has good precision processability and dimensional accuracy, especially fire protection prescribed by the Ministry of Construction. In the heating test according to the door test method, it does not cause harmful changes in fire protection and has the prescribed fire protection performance.
The present invention relates to a transparent non-expandable crystallized glass that can be used as (provided at the opening of a fireproof section to prevent the spread of fire and spread of fire in a building).

[0002]

[Prior Art and Problems] Japanese Patent Publication No. 39-21049 discloses SiO ₂
Disclosed is a transparent crystallized glass of the —Al ₂ O ₃ —Li ₂ O system, which contains Na ₂ O and P ₂ O ₅ as essential components and TiO ₂ and ZrO ₂ as nucleation components.

Na ₂ O is suitable as a solvent for melting glass at a relatively low temperature and as a glass formability improving agent, but if an appropriate amount is introduced to exert its effect, the coefficient of thermal expansion increases. In order to aim at non-expansion crystallized glass, divalent components that do not increase the thermal expansion coefficient so much, namely MgO and Zn.
A proper amount of O, BaO, etc. must be present together. .

JP-A-3-37135 discloses that SiO₂−Al₂O₃-Li
₂O-based, MgO, ZnO, P as essential components₂O_Five, And karyotype
TiO as a component₂, ZrO₂Including as an optional ingredient
Na ₂OK₂Transparent crystallized glass containing O 2 is disclosed
You. Further, in Japanese Patent Laid-Open No. 6-92681, similar SiO₂−Al₂O₃
-Li₂O-based, MgO, ZnO, BaO, and
TiO as nucleation component₂, ZrO₂, As an optional ingredient
P₂O_FiveTransparent crystallized glass containing
It has been disclosed.

As described above, Na ₂ O should be indispensable for improving the meltability and moldability of glass, and in order to suppress the adverse effect, introduction of an excessive amount is suppressed, and the meltability and moldability of glass are separately controlled. It is necessary to introduce an appropriate amount of a divalent component for improving the properties of MgO, ZnO and BaO, and these known examples are insufficient in that respect.

Japanese Unexamined Patent Publication No. 64-52631 discloses SiO ₂ --Al ₂ O ₃ --Li.
_{In the 2} O system, SnO ₂ , ZrO ₂ as a nucleating component, or
Comprises TiO _2, MgO as an optional _{component, ZnO, BaO, Na 2 O} ,
A transparent crystallized glass containing K ₂ O and P ₂ O ₅ is disclosed. However, in the case where SnO ₂ is introduced, it is known that SnO ₂ easily gives cloudiness to glass, and strict heating conditions are required for heat treatment.

The present invention solves the problems and problems of the prior art, is excellent in glass melting and forming properties, is colorless and has good transparency, and has a thermal expansion coefficient of 0 or around 0, heat resistance and fire protection. Provided is a crystallized glass having good properties, particularly a transparent non-expandable crystallized glass which is useful as a heat resistant and fireproof window.

[0008]

[Means for Solving the Problems] The present invention relates to SiO.₂ 59 ~
63wt%, Al₂O₃ 21-24wt%, MgO 1-3wt%, ZnO1-
3 wt%, Li₂O 4-5 wt%, TiO₂ 1-3 wt%, ZrO₂ 1 to 4
wt%, P₂O_Five 1 to 3 wt%, BaO 0.5 to 2 wt%, Na₂O 0.5 ~
Included in the range of 2 wt%, As for 100 wt% of the above composition ₂O₃ 0.
Extrapolated in the range of 5 to 2 wt% and Al₂O₃ , Li
₂The mole fractions of O, MgO and ZnO are a, l, m and
And zn satisfy the formula 0.9 ≦ a / (l + m + zn) ≦ 1.1.
The crystallization gas obtained by heat-treating the original glass
Lath, mainly containing β-quartz crystal phase,
Expansion coefficient 0 ± 5 × 10^-7/ Non-swelling within the range of ℃
It consists of crystalline glass.

The transparent non-expandable crystallized glass of the present invention is colorless or almost colorless and has excellent transparency and has a coefficient of thermal expansion of 0 ± 5 × 10 ⁻⁷ / ° C. (at room temperature or
It is a crystallized glass near 300 ° C) and almost zero.

According to the present invention, it can be used as a heat-resistant and fire-proof window, which has been rapidly increasing in demand in recent years, that is, as an A-class fire door provided in an opening portion for preventing the spread and spread of fire in a building. Further, since it has an advantage that a dimensional error due to heat or the like is unlikely to occur during cutting or cutting by laser irradiation or the like, it can be effectively applied as an electronic substrate or the like.

Regarding each component composition of the raw glass in the present invention, SiO ₂ is 59 wt% as a main forming component of β-quartz crystal phase.
It is introduced in the range of up to 63 wt%, and if it is less than 59 wt%, the crystal grains become uneven and white turbidity due to coarse crystals is likely to occur. On the other hand, if it exceeds 63 wt%, the homogeneity of the glass melt becomes difficult and the crystallized glass tends to become cloudy and the transparency tends to deteriorate.

[0012] The main crystal phase components of the component system and the β- quartz, similar to β- quartz, therewith to form a solid solution phase β- eucryptite _{(Li 2 O. Al 2 O 3} . 2SiO 2 (However, MgO and ZnO can substitute for Li ₂ O), and these are collectively referred to as β-quartz. Al ₂ O ₃ is contained as an essential component in the formation of β-eucryptite in the range of 21 to 24 wt%. If it exceeds 24 wt%, the melting and homogeneity of glass and moldability become difficult, and less than 21 wt%. In that case, the precipitation of crystals becomes insufficient, and the coefficient of thermal expansion of the crystallized glass also increases.

Li ₂ O, which is a similar crystallization component, is 4 to 5 wt%
If the content exceeds 5 wt%, the crystallization tendency becomes remarkable and coarse crystals are easily deposited, making it difficult to form a clear crystallized glass. The coefficient of thermal expansion itself is negative, and the β-eucryptite system that adjusts the coefficient of thermal expansion of crystallized glass to around 0 is insufficient.

MgO is used in an amount of 1 to 3 wt% in order to improve the glass melting and forming properties and to replace Li ₂ O forming the crystal phase.
If it exceeds 3 wt%, the thermal expansion coefficient increases and the heat resistance deteriorates. If it is less than 1 wt%, glass melting becomes difficult, and homogeneous fine crystals precipitate during heat treatment. To make it difficult.

ZnO improves the glass melting / formability and can itself replace MgO with Li ₂ O to form a crystalline phase component. Further, it is useful for forming microcrystals during heat treatment and improving the transparency of the crystallized glass, but it is introduced in an amount of 1 wt% or more in order to exert these effects.
However, if it is introduced in excess of 3 wt%, the coefficient of thermal expansion will increase,
In addition, the heat resistance is likely to be impaired, so the range is 3 wt% or less.

When the mole fractions of Al ₂ O ₃ , Li ₂ O, MgO and ZnO are respectively a, l, m and zn, the formula a / (l +
m + zn) is in the range of 0.9 or more and 1.1 or less. If it is out of this range, it is difficult to obtain crystallized glass having excellent transparency.

ZrO ₂ is indispensable as a nucleation component together with TiO ₂ , and is introduced in a range of 1 to 4 wt% in order to form a necessary and sufficient amount of crystal nuclei and uniformly disperse it.
If it is less than 1 wt%, the nucleation becomes insufficient, while if it exceeds 4 wt%, it becomes difficult to melt the glass, and in addition, white turbidity is easily given to the crystallized glass.

TiO _2, which is a similar nucleating component, is introduced in the range of 1 wt% to 3 wt% in equilibrium with the above ZrO _2.
If it is less than%, the nucleation is insufficient, while if it exceeds 3 wt%, it gives a yellowish coloring to the glass, which is unsuitable. The amount of ZrO ₂ + TiO ₂ is preferably about 4 wt% to 5 wt%.

BaO acts effectively as a solvent and a formability improving agent when melting glass, and the glass raw material is used at a relatively low temperature.
It is useful for melting and homogenizing in a short time, improving the moldability of glass, and in addition, precipitating homogeneous and fine crystals during heat treatment and crystal precipitation to form crystallized glass with good transparency. The above-mentioned MgO and ZnO have some similar effects, but the introduction amount is limited as described above.
The introduction of O 2 makes it possible to exert its action effect. For that purpose, it is necessary to introduce 0.5 wt% or more, but if it is introduced in excess of 2 wt%, coarse crystals will be precipitated during the heat treatment and the transparency of the crystallized glass tends to be impaired, so it is set to 2 wt% or less.

Similarly, Na ₂ O is extremely effective as a fluxing agent superior to BaO, and together with BaO, glass raw materials can be used at relatively low temperatures,
Melts and homogenizes in a short time to improve moldability, and when heat treatment and crystal precipitation, homogeneous and fine crystals are deposited to form crystallized glass with good transparency. In order to exert these effects, 0.5 wt% or more is introduced.
If it is introduced in excess of t%, the coefficient of thermal expansion of glass will increase,
Further, coarse crystals are precipitated during the heat treatment, and the transparency of the crystallized glass is liable to be impaired.

The present invention has the advantage that it can be melted at a lower temperature than conventional crystallized glass, and therefore glass formation is easy. When melting glass, Na ₂ O is very excellent as a flux, but on the other hand, there is a problem that the coefficient of thermal expansion of glass is increased. On the other hand, BaO is inferior as a fluxing agent, but has little effect on the thermal expansion coefficient of glass, and therefore it is essential to use both components together. The total amount of BaO + Na ₂ O is preferably about 1 wt% to 3 wt%.

P ₂ O ₅ is effective in promoting melting of ZrO ₂ content and also has a nucleating action. In order to exert its action and effect, it is necessary to introduce 1 wt% or more, while if it is introduced in excess of 3 wt%, cloudiness is likely to occur in the glass.

As ₂ O ₃ is introduced as a fining accelerator, and its effect is exhibited by introducing 0.5 wt% or more with respect to 100 wt% of each of the above-mentioned components in total, but when it exceeds 2 wt%, coloring is given, No further improvement in fining effect is observed, so 2
Introduce in the range of wt% or less. In addition, a part of As ₂ O ₃ is converted into Sb ₂ O ₃
It can be replaced with.

In the present invention, a coloring component such as TiO ₂ ,
Incorporation of Fe ₂ O ₃ , CoO, NiO, MnO ₂ ----, etc. impedes the colorless transparency of the crystallized glass and must be avoided as much as possible.

The crystallized glass of the present invention is produced by the following procedure. Preparation of raw materials; quartz powder as SiO ₂ source, aluminum hydroxide as Al ₂ O ₃ source, lithium carbonate as Li ₂ O source, magnesium carbonate as MgO source, zinc white as ZnO source, zircon sand as ZrO ₂ source, P ₂ O Phosphoric acid was used as the ₅ source, sodium nitrate was used as the Na ₂ O source, barium nitrate was used as the BaO source, and arsenous acid was used as the As ₂ O ₃ source. Predetermined amounts were respectively weighed according to the desired composition and thoroughly mixed with a mixer.

It is needless to say that the raw material is not limited to the above-mentioned raw material, and the raw material may be appropriately selected, but attention must be paid to the mixing of the coloring impurities. Note that nitrates such as sodium nitrate and barium nitrate are effective in promoting melting and are suitable for melting at a relatively low temperature.

Melt: Fill the raw material for corrosion with a corrosion-resistant heat-resistant container such as a platinum crucible, and heat it in a heating furnace such as an electric furnace at 1500 ° C. to 16 ° C.
Melt and homogenize at 00 ° C for 3 to 7 hours. In the component system of the present invention, low temperature melting is possible as compared with the conventional melting of crystallized glass, and it is effective in industrial mass production.

Molding: Molten glass is molded in a molding temperature range of 1000 ° C. to 1300 ° C. by appropriate molding means such as pouring into a mold and roll-out. The glass after molding may be subjected to a heat treatment in the next step in the cooling process, or may be once cooled and then reheated and heat treated.

Heat treatment (crystallization): Two-step heat treatment of nucleation and crystallization is desirable. For example, 700 ℃ ~ 750 ℃ in the heating furnace
It is heat-treated at 750 ° C. to 800 ° C. for several hours to be crystallized. In the component system of the present invention, nucleation and crystallization with excellent transparency are easy as compared with conventional crystallized glass, and it is effective in industrial mass production. As described above, the transparent non-expandable crystallized glass can be easily obtained by preparing the raw materials, melting, molding, and heat-treating and then allowing to cool.

The crystallized glass can be particularly used as a heat-resistant and fire-proof window as a material for type A fire doors, that is, the opening of a predetermined test furnace based on the fire door test method of Ministry of Construction Notification No. 1125, 1990. According to the test that fire resistance was tested by setting it on the part and heating it according to the prescribed heating curve, no problems such as cracks in the crystallized glass, penetration of flame, etc. occur even at 925 ° C for 60 minutes after the start of heating. . This is because the coefficient of thermal expansion of the crystallized glass of the present invention is close to 0, and strain due to thermal expansion hardly occurs during heating.
In addition, it is suitable for a class A fire door (provided at the opening to prevent the spread of fire and the spread of fire in a building) because it does not deform or fall off even if a shock is applied under predetermined conditions in an impact test after heating.

[0031]

EXAMPLES The present invention will be described in detail below with reference to Examples and Comparative Examples. In order to obtain a raw glass having various target compositions as shown in Table 1, the raw material was prepared and charged into a platinum crucible as described above, and 1500 ° C to 1600 ° C in an electric furnace (16 in the comparative example).
(Unmelted remains at 00 ℃, 1650 ℃), 3hr ~ 7h
After melting at r, the glass was cast onto a heat-resistant metal plate to form a plate-shaped (original) glass. For the raw glass, the thermal expansion coefficient, transition point, and yield point are measured by a thermal expansion meter, and the high temperature viscosity-temperature is measured by a viscometer. [Viscosity over 1500 ° C is calculated by the well-known Fulcher equation: log μ = -A + B / (TT ₀ ) ABT ₀ is a constant, T is absolute temperature], and the transparency and color tone of the appearance were observed. Table 1 shows the transition point, yield point, temperature at 10 ² poise, coefficient of thermal expansion, and appearance observation results of the raw glass.

Next, these were heated in two stages under the heat treatment conditions shown in Table 2 to obtain crystallized glass. Measure the coefficient of thermal expansion of the obtained glass at room temperature to 300 ℃ with a thermal expansion meter,
The crystal phase was identified by X-ray diffraction, and the appearance was observed in the same manner as above. The results are also shown in Table 2.

Although two examples of heat treatment conditions were shown depending on the sample, as is clear from the display, even if the heat treatment conditions are changed, good transparent crystallized glass can be obtained although a slight difference is observed in the coefficient of thermal expansion.

For more major samples, the Ministry of Construction Notification Heisei
Based on the fire door test method of No. 1125 of the 2nd year, set it in the opening of the specified test furnace and heat it according to the specified heating curve. The occurrence of penetration, etc. was observed, and after heating, it was given an impact under a predetermined condition to see if it was deformed or dropped off, and the application to a class A fire door was investigated. The results are summarized in Table 2.

In Tables 1 and 2, sample Nos. 1 to 9 are Examples, and 10 to
14 is a comparative example.

[0036]

[Table 1]

[0037]

[Table 2]

In the graph of FIG. 1, when the vertical axis represents the respective mole fractions of Al ₂ O ₃ , Li ₂ O, MgO and ZnO in the glass, a / (m / zn). l + m + zn) molar ratio, SiO ₂ wt% in the glass on the horizontal axis was taken, each Example sample and Comparative Example sample were plotted, and transparent clear crystallized glass was marked with ○, cloudiness etc. It is clearly shown that all the samples of the examples surrounded by the broken line frame and within the composition condition range of the present invention are transparent and clear.

From the above, in the crystallized glass of the present invention shown in sample Nos. 1 to 9 (Example), the viscosity of the raw glass is lower than that of the comparative example, and melting and refining are easy.
Further, the crystallized glass has a low coefficient of thermal expansion of 0 ± 5 × 10 ⁻⁷ / ° C., is almost colorless and transparent, and satisfies the Class A fire door regulations in the fire door test.

In the crystallized glasses according to the conventional examples of sample Nos. 10 to 14 (comparative examples), the viscosity of the raw glass is high, and a high temperature of 1650 ° C. or higher is required for melting and refining. In addition, it is clear that the crystallized products are inferior to those in the examples in that some white or cloudiness is observed, or cracks are more likely to occur.

[0041]

EFFECTS OF THE INVENTION According to the present invention, the raw glass can be easily melted and molded, and the crystallized glass is clear and excellent in transparency, and has a coefficient of thermal expansion close to 0 and excellent heat resistance.
It is suitable as a glass for A-type fire doors and also useful as an electronic substrate.

[Brief description of drawings]

FIG. 1 shows the a / (l + m + zn) molar ratio, where the vertical axes represent the molar fractions of Al ₂ O ₃ , Li ₂ O, MgO and ZnO in the glass, respectively a, l, m and zn. Is the SiO ₂ wt.
It is the graph which took% and plotted each Example and comparative example sample.

Claims (1)

[Claims] 1. SiO₂ 59-63wt%, Al₂O₃ 21-24wt%, Mg
O 1-3 wt%, ZnO 1-3 wt%, Li ₂O 4-5 wt%, TiO₂
 1-3 wt%, ZrO₂ 1 to 4 wt%, P₂O_Five 1-3 wt%, BaO 0.
5 to 2 wt%, Na₂O 0.5 to 2 wt% in the above composition
 As for 100 wt%₂O₃ Extrapolated in the range of 0.5 to 2 wt%
And become Al₂O₃ , Li₂O, MgO and ZnO moles
For each of the a, l, m and zn, the equation 0.9 ≤ a / (l + m
+ zn) ≦ 1.1, heat treatment of the original glass in the range,
Crystallized crystallized glass, mainly β-stone
Includes an English crystal phase and has a thermal expansion coefficient of 0 ± 5 × 10^-7/ ° C
Transparent non-expanding crystallized glass characterized by a range
Su.