Glass panel unit
View Patent ↗The glass panel unit includes a first glass panel, a second glass panel, a seal, an evacuated space, and a spacer. The second glass panel is placed opposite the first glass panel. The seal with a frame shape hermetically bonds the first glass panel and the second glass panel to each other. The evacuated space is enclosed by the first glass panel, the second glass panel, and the seal. The spacer is placed between the first glass panel and the second glass panel. The spacer is a stack of two or more films. At least one film of the two or more films contains a polymer having a viscoelastic coefficient at 400° C. larger than 500 MPa.
1. A glass panel unit comprising:
a first glass panel;
a second glass panel placed opposite the first glass panel;
a seal with a frame shape hermetically bonding the first glass panel and the second glass panel to each other;
an evacuated space enclosed by the first glass panel, the second glass panel, and the seal; and
at least one spacer placed between the first glass panel and the second glass panel, wherein:
the at least one spacer is a stack of two or more films,
at least one film of the two or more films contains a polymer having a viscoelastic coefficient at 400° C. larger than 500 MPa, and
the polymer has a coefficient of thermal expansion at 400° C. smaller than 10 ppm/° C.
2. The glass panel unit of claim 1 , wherein
the evacuated space is made to be in a vacuum state through evacuation with heating.
3. The glass panel unit of claim 2 , wherein
a temperature for the heating is equal to or higher than 300° C.
4. The glass panel unit of claim 1 , wherein
the first glass panel and the second glass panel each are devoid of an outlet.
5. The glass panel unit of claim 1 , wherein
an area ratio of the at least one spacer to the glass panel unit in a plan view is in a range of 0.01 to 0.2%.
6. The glass panel unit of claim 1 , wherein
the at least one spacer contains at least one material selected from glass, metal, ceramic, and graphite.
7. The glass panel unit of claim 1 , wherein
a ratio of a viscoelastic coefficient V400 of the polymer at 400° C. to a viscoelastic coefficient V20 of the polymer at 20° C. (V400/V20) is equal to or larger than 0.1.