JP2002047030A - Heat resisting glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide glass capable of melting and forming with float method which is high in softening point, suitable for heat resistant glass especially for heat resistant and fireproof glass because of strengthened for heat resisting. SOLUTION: This heat resisting glass consists of 55-60 wt.% SiO2, 15-24 wt.% Al2O3, 5-8 wt.% B2O3, 0.5-2 wt.% Li2O, 2-4 wt.% Na2O, 0-4 wt.% K2O, 3-7 wt.% MgO, 4-9 wt.% CaO, (where, SiO2+Al2O3+B2O3: 75-88 wt.%, Li2O+Na2 O+K2O: 3-7 wt.%, MgO+CaO: 7-13 wt.%), substantially free from ZnO.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of melting by a float process and forming a sheet glass, has a softening point much higher than that of soda-lime-silica glass, and can heat-enhance the peripheral portion or the entire surface of the sheet glass, The present invention relates to a heat-resistant glass suitable as glass, particularly as glass for class B and class A fire doors.

[0002]

_2. Description of the Related Art Conventionally, SiO ₂ —Al ₂ O ₃
So-called aluminoborosilicate glass composed of —B ₂ O ₃ —R ₂ O (R: alkali metal) —R′O (R ′: divalent metal) has been proposed in many cases, and they are soda-lime. Although it has a higher softening point and higher heat resistance than silica-based glass, it has a very high melting temperature, so that it is difficult to melt by ordinary heating and melting means, and it has been difficult to melt by a so-called float method and form a sheet glass.

JP-A-60-42247, JP-A-60-12274
No. 8 and JP-A-7-53235 disclose a glass composition containing a ZnO component in an aluminoborosilicate glass, but in sheet glass forming by a float method, the glass is reduced to a reducing atmosphere in a tin bath. ZnO is easily volatilized, which causes deterioration of the tin bath. Therefore, ZnO must be avoided.

Japanese Patent Application Laid-Open No. 3-40933 discloses a glass composition containing a ZrO ₂ component in an aluminoborosilicate glass, but the ZrO ₂ raw material itself is hardly meltable.
The incorporation of ZrO ₂ should be avoided because it tends to cause inhomogeneities such as striae in the glass.

The present invention solves the above-mentioned disadvantages,
An object of the present invention is to provide a glass composition which can be melted and formed by a float method, has a high softening point, and is suitable as a heat-resistant glass, particularly a heat-resistant fireproof glass by heat strengthening.

[0006]

According to the present invention, SiO ₂ : 55 to 60, Al ₂ O ₃ : 15 to 24, B ₂ O ₃ : 5 to 8, Li _{2
O: 0.5~2, Na 2 O:} 2~4, K 2 O: 0~4, MgO: 3~
7, CaO: 4-9, (however, SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ : 75-88, L
_{i 2 O + Na 2 O +} K 2 O: 3~7, MgO + CaO: 7~13) a and,
It is a heat-resistant glass that does not substantially contain ZnO.

In the above, the average thermal expansion coefficient of glass at 30 to 300 ° C .: 50 × 10 ⁻⁷ / ° C. or less, softening point: 850 ° C. or more, 1
0 ² poise temperature (melting temperature): 1600 ° C. or less, 10 ⁴ poise temperature
(Working temperature): It is preferable to be 1200 ° C. or less.

Further, it is preferable that the glass is heated to a temperature equal to or lower than the softening point and in the vicinity of the softening point, and then the peripheral portion of the glass or the entire glass is rapidly cooled to provide fire resistance.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The composition range of glass in the present invention is as follows.

[0010] SiO ₂ : a main component forming a glass skeleton, contained in the glass in the range of 55 to 60% (% by weight, the same applies hereinafter). If it is less than 55%, devitrification tends to be easily crystallized, and accordingly, sheet glass forming tends to be difficult. If it exceeds 60%, the viscosity of the glass increases to increase the melting temperature, and the working temperature (forming temperature) is increased to deteriorate the melting and formability.

Al ₂ O ₃ : In order to increase the softening point of the glass and impart heat resistance, it is contained in the glass in the range of 15 to 24%.
If it is less than 15%, the softening point decreases, and if it exceeds 24%, devitrification tends to occur.

B ₂ O ₃ : To adjust the coefficient of thermal expansion of the glass, to suppress the occurrence of devitrification, and to improve the melting property, B is contained in the glass in the range of 5 to 8%. If it is less than 5%, the above effects cannot be exerted, and if it exceeds 8%, devitrification tends to occur and melting tends to be difficult.

SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ : 75 in glass
It is contained in the range of ~ 88%. If it is less than 75%, the glass softening point is lowered, and the heat resistance is easily impaired. If it exceeds 88%, the glass viscosity increases and the melting temperature is raised, and the working temperature (forming temperature) is raised to improve the melting and formability. Getting worse.

Li ₂ O: A suitable component for improving the melting property of glass, and is contained in the glass in the range of 0.5 to 2%. If it is less than 0.5%, the above effect cannot be exhibited, and if it exceeds 2%, the glass softening point is excessively lowered.

Na ₂ O: To improve the melting property of the glass and to maintain the coefficient of thermal expansion at an appropriate level. The content is 2 to 4% in the glass. If it is less than 2%, the melting property deteriorates, and the glass softening point exceeding 4% is excessively lowered.

K ₂ O: As in the case of Na ₂ O, in order to improve the melting property of the glass and maintain an appropriate coefficient of thermal expansion, it is contained as necessary in the range of 0 to 4%. If it exceeds 4%, the glass softening point decreases.

Li ₂ O + Na ₂ O + K ₂ O: In particular, in order to improve the melting property of the glass, it is contained in the glass in a total range of 3 to 7% as described on the left. If it is less than 3%, the effect cannot be exhibited, and if it exceeds 7%, the glass softening point is excessively lowered.

MgO: contained in the range of 3 to 7% for adjusting the glass softening point, adjusting the thermal expansion coefficient, and improving the melting property. If it is less than 3%, there is no effect on glass melting, and if it exceeds 7%, devitrification tends to occur.

CaO: Like MgO, it is contained in the range of 4 to 9% for adjusting the glass softening point, adjusting the thermal expansion coefficient, and improving the melting property. Less than 4% has no effect on glass melting,
If it exceeds 9%, devitrification tends to occur, and the devitrification growth rate also increases.

MgO + CaO: In order to adjust the glass softening point, adjust the coefficient of thermal expansion, and improve the meltability, the total of 7
It is contained in the range of ~ 13%. If it is less than 7%, there is no effect on glass melting, and if it exceeds 13%, devitrification tends to occur.

Incidentally, NiO, CoO, Cr as coloring components
₂ O ₃ , Se, CeO ₂ , TiO ₂ , Fe ₂ O ₃ , MnO ₂ components etc. 2 wt.
% Or less.

It goes without saying that mirabilite, arsenous acid, antimony acid and the like as a fining agent can be optionally added.

In the present component system, the ZnO component is liable to volatilize in a reducing atmosphere in a metal bath (tin bath) during float molding, and causes deterioration of the metal bath. However, when it is mixed as an impurity in the raw material or a contamination in the glass cullet, it is acceptable if the content is 0.5 wt% or less in the glass.

In the present invention, preferably, the glass density (ρ) is desirably 2.50 × 10 ³ kg · m ⁻³ or less, whereby the weight of the glass can be reduced. It is known that the lower the glass density, the higher the toughness of the glass tends to be.

In the present invention, the glass softening point is 850 ° C.
By doing so, the soda-lime glass (the softening point is approximately
(720 to 730 ° C).

Further, by setting the coefficient of thermal expansion of the glass at 30 to 300 ° C. to 50 × 10 ⁻⁷ / ° C. or less, the degree of thermal distortion at the time of temperature rise or temperature fluctuation is significantly reduced as compared with soda-lime glass or the like. Reduction, cracks and cracks can be minimized.

The glass breaks due to thermal distortion of the peripheral edge of the glass sheet when heated to an elevated temperature. Therefore, if the peripheral edge of the glass sheet having a high softening point having heat resistance is thermally strengthened, the performance as a fireproof glass is improved. Is already known, and of course, the entire sheet glass may be thermally strengthened.

In the present invention, the entirety of the periphery of the sheet glass is thermally strengthened, or the entire sheet glass is thermally strengthened, so that the type B fire door (heated at 795 ° C. for 20 minutes) and the type A fire door (925 ° C., 60 minutes) Heat-resistant glass suitable as a window for heating). At the time of thermal strengthening, if the heating temperature of the glass exceeds the softening point, the glass is likely to be deformed, so that the temperature is not higher than the softening point.
The softening point is preferably in the range of softening point to -100 ° C.

Further, the glass of the present invention, 10 ² poise temperature
(Melting temperature) of 1600 ° C. or less, is 10 ⁴ poise temperature (working temperature) 1
Since the temperature is 200 ° C. or lower, melting and molding by a normal float kiln or float bath are possible, and other sheet glass manufacturing methods such as a roll-out method and a fusion method can be applied.

[0030]

Embodiment A The present invention will be described below with reference to specific embodiments. Quartz sand as [Sample Preparation] SiO ₂ source, aluminum oxide as Al ₂ O ₃ source, boric acid (anhydride) as a B ₂ O ₃ source, Li ₂ O
Lithium carbonate as a source, sodium carbonate as a Na ₂ O source,
Potassium carbonate was prepared as a K ₂ O source, magnesium oxide was prepared as a MgO source, and calcium carbonate was prepared as a CaO source.

These raw materials are mixed in a desired ratio, and the capacity is 2 L
After filling in a platinum-rhodium crucible,
After setting in an electric furnace set to a temperature of 700 ° C. and heating and melting for 4 hours, the furnace temperature was lowered to 1300 to 1400 ° C. and kept for another 4 hours for fining homogenization. Next, the crucible was taken out of the furnace, and the molten glass was poured on a carbon plate to obtain a plate-like glass. Further, the sheet glass was set in an electric furnace previously set at a temperature of 700 to 800 ° C., and after holding for 3 hours, the heating of the furnace was stopped and the furnace was allowed to cool, thereby obtaining sample glasses shown in Tables 1 and 2.

[Various Measurements and Results] A part of each sample glass was subjected to component analysis, and a part was cut out into a rod shape.
Thermal expansion coefficient at 30 to 300 ° C. The (α × 10 ^-7 / ℃) were measured, further melting temperature by partially cut out the block-shaped sphere pulling viscometer (10 ² poise temperature: ° C.) and working temperature ( 10 ⁴ poise temperature: ° C.), separately processed into a thin line, and then the softening point (10 ^7.6 poise temperature) was measured by the Littleton method. Furthermore, the density (ρ: 10 ³ kg · m ^-3 ) of the glass block was measured by the Archimedes method.

Tables 1 and 2 show the results of various analyzes and measurements.
In this embodiment the range, 10 ² poise temperature (melting temperature) of 160
0 ℃ below 10 ⁴ there is poise temperature (working temperature) of 1200 ° C. or less, so-called float furnace, melted by the float bath, is capable of forming, softening point as high as 850 ° C. or higher, and 30 to 3
When the average thermal expansion coefficient at 00 ° C. is as low as 50 × 10 ⁻⁷ / ° C. or less, the heat resistance is high, the degree of thermal distortion is significantly reduced, and the generation of cracks and cracks can be reduced as much as possible.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Example B] [Preparation of fire door test glass] Each of the raw material preparations in Examples 3, 4 and Comparative Example 1 was filled in a crucible in the same manner as in Example A, and set in an electric furnace. Then, the mixture was melted and clarified in the same manner as in Example A, poured into a carbon mold to form a sheet glass, and then gradually cooled to obtain sample glasses each having a thickness of about 7 mm.

Each sample glass was cut into a square of 20 cm × 20 cm, and the edge was chamfered and polished, and then placed in an electric furnace and heated to a temperature almost equal to the softening point of glass -70 ° C. Immediately after being taken out, the entire sample glass was blown with cold air to strengthen it.
A sample (corresponding to Example 3), an Example 4 * sample (corresponding to Example 4), and a Comparative Example 1 * sample (corresponding to Comparative Example 1: soda-lime glass) were obtained.

[Fireproof Door Test and Results] For each of the sample glasses of Example 3 *, Example 4 *, and Comparative Example 1 *, they were fitted into a heat-resistant frame arranged at the opening of the fireproof fireproof test apparatus, and the incombustible filler was used. And then heated at 925 ° C for 60 minutes according to the heating method in the Class A fire door test notified by the Ministry of Construction.

In Example 3 * and Example 4 *, the undulation of the glass plate was observed after heating for 60 minutes, but no crack was generated, the glass plate was fixed to the frame, the flame was not blown out, and the heating test was completed. did. On the other hand, in Comparative Example 1 * (soda-lime glass), the test was immediately stopped because the glass broke within 5 minutes after the start of heating. The so-called super-strengthened soda-lime glass can be used at least for the fire test of type B (heating for 20 minutes), but it is considered that the degree of strengthening was insufficient in this comparative example.

In the class A fire door test, it is stipulated that a sand bag having a specific weight is caused to collide in the impact test after the heating test. However, in Examples 3 * and 4 *, there is no crack, breakage or the like. , Because it is firmly fixed to the frame,
It was not difficult to imagine that it could withstand the impact test sufficiently, and it was determined that it could be applied as a Class A fire door.

[0041]

The glass of the present invention has heat resistance and can be applied not only as a normal window glass but also as a substrate for a display device such as a liquid crystal substrate or a PDP substrate.

Further, it is possible to thermally strengthen the peripheral portion or the entire surface of the plate glass, and the thermally strengthened glass has an effect that it can be applied as a type B and a type A fire door.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor, Panshi Machishita 1510, Oguchi-cho, Matsusaka-shi, Mie Central Glass Co., Ltd. Glass Research Laboratory F-term (reference) 4G015 CA04 CB01 4G062 AA01 BB01 BB06 DA06 DB04 DC03 DD01 DE01 DF01 EA02 EA03 EB03 EC01 EC02 EC03 ED03 EE03 EF01 EG01 FA01 FA10 FB01 FC01 FD01 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 NN07 KK NN KK NN33

Claims (3)

[Claims] 1. The method according to claim 1, wherein the SiO._Two: 55-60, Al_TwoO_Three： 15
~ 24, B_TwoO_Three: 5-8, Li_TwoO: 0.5% -2, Na_TwoO: 2-4,
K_TwoO: 0 to 4, MgO: 3 to 7, CaO: 4 to 9, (provided that SiO_Two+
Al_TwoO _Three+ B_TwoO_Three: 75-88, Li_TwoO + Na_TwoO + K_TwoO: 3-7, MgO
+ CaO: 7 to 13), which means that ZnO is not substantially contained.
Characterized heat-resistant glass. 2. The average thermal expansion coefficient of glass at 30 to 300 ° C .: 50
× 10 ^-7 / ° C. or less, a softening point: 850 ° C. or higher, 10 ² poise temperature
(Melting temperature): 1600 ° C. or less, 10 ⁴ poise temperature (working temperature): 1
2. The heat-resistant glass according to claim 1, wherein the temperature is 200 ° C. or lower. 3. The method according to claim 1, wherein the sheet glass is heated to a temperature below the softening point and in the vicinity of the softening point, and then the periphery of the glass or the whole glass is rapidly cooled to provide fire resistance. 2. The heat-resistant glass according to 2.