Fireproof sheet glass

Details Fireproof sheet glass Fireproof sheet glass

1998-07-20

2000-04-25

Group, Karl

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

501 72, C03C 8087

Patent

active

060544015

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a fireproof sheet glass, and more particularly to a fireproof sheet glass formed of glass composition which should be classified as a soda-lime glass.
Conventionally, no fireproof sheet glass of the above-noted type is known which achieves a high fireproof performance in the event of a fire. According to some conventional practices, an ordinary soda-lime glass composition would be formed into a wire glass to be utilized as a fireproof sheet glass, or a heat-tempered glass would be made from a soda-lime glass composition to be utilized as a fireproof sheet glass. Incidentally, although it is conceivable to form a fireproof sheet glass from one having a high melting point, such as borosilicate glass, such glass results in low productivity of the sheet glass due to its high melting point, high viscosity and so on. Further, if the glass contains boron, this will tend to reduce the life of the glass melting furnace. Therefore, there has been a demand for providing a fireproof sheet glass using soda-lime glass and there have been conducted intensive researches in this respect.
Incidentally, although the conventional fireproof sheet glass noted above achieves good fireproof performance at an earlier stage of fire, none are known to exist which can satisfy the requirement of A class fire door (according to a fireproof test based on Notice by Japanese Ministry of Construction Serial No. 1125). For instance, the fireproof sheet glass described above does not break when exposed to a fire, thus preventing spread of the fire. However, after lapse of a predetermined period of time, there is observed a phenomenon that the glass itself softens and will escape from e.g. a sheet-glass holding member (sash, frame). Thus, it cannot maintain its shape for 60 minutes according one requirement of the above standard.
Accordingly, an object of the present invention is to provide a fireproof sheet glass which uses soda-lime glass, yet which can satisfy the standard of A glass fire door.
The present inventors discovered that when a sheet glass is heated in accordance with the A class fire door standard, it can reach 770.degree. C.-780.degree. C. by the 60 minutes of heating and further that a sheet glass formed of a glass composition having a melting point of 780.degree. C. or higher has greater possibility of conforming to the above standard.
Then, the present inventors employed, as a fireproof sheet glass, a following glass composition (wt.%) having superior fire resistance previously developed by the present inventors and newly found out that this can suitably satisfy the above standard. Namely;


______________________________________ SiO.sub.2 56.about.68% Al.sub.2 O.sub.3 0.2.about.5% ZrO.sub.2 0.about.3% Li.sub.2 O 0.about.0.5% Na.sub.2 O 0.2.about.4% K.sub.2 O 6.about.14% MgO 1.about.14% CaO 6.about.12% SrO 0.about.12% BaO 0.about.13% ZnO 0.about.2%; and; Na.sub.2 O + K.sub.2 O 8.about.14% MgO + CaO 8.about.15% SrO + BaO 8.about.14% MgO + CaO + SrO + BaO 20.about.27% SO.sub.3 + Sb.sub.2 O.sub.3 0.about.1% and; ______________________________________
the composition has an average thermal expansion ratio at 50.about.350.degree. C. of 75.about.95.times.10.sup.-7 /K;
the composition has a warping point of 540.degree. C. or higher; and
the composition has a 10.sup.2 poise temperature of 1560.degree. C. or lower.
Then, for accomplishing the above-noted object, a fireproof sheet glass, according to the characterizing features of the present invention, comprises a composition, in the unit of wt. % of


______________________________________ SiO.sub.2 56.about.68% Al.sub.2 O.sub.3 0.2.about.5% ZrO.sub.2 0.about.3% Li.sub.2 O 0.about.0.5% Na.sub.2 O 0.2.about.4% K.sub.2 O 6.about.14% MgO 1.about.14% CaO 6.about.12% SrO 0.about.12% BaO 0.about.13% ZnO 0.about.2%; where, Na.sub.2 O + K.sub.2 O 8.about.14% MgO + CaO 8.about.15% SrO + BaO 8.about.14% MgO + CaO + SrO

REFERENCES:
patent: 5631195 (1997-05-01), Yanagisawa et al.
patent: 5656558 (1997-08-01), Brix et al.
patent: 5763343 (1998-06-01), Brix et al.
patent: 5776844 (1998-07-01), Koch et al.
patent: 5925583 (1999-07-01), Yoshii et al.

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