Glass panel unit, work in progress of glass panel unit, glass panel unit assembly, and method for manufacturing glass panel unit
A glass panel unit includes: a pair of glass panels arranged to face each other; and a frame member disposed between the pair of glass panels to hermetically bond the pair of glass panels together. The frame member includes: a body; and a reinforcing portion. The body has a frame shape and includes: a first part containing a first sealing material having a first softening point; and a second part containing a second sealing material having a second softening point that is higher than the first softening point. The reinforcing portion contains a third sealing material having a third softening point that is higher than the first softening point. The reinforcing portion is adjacent to the first part in a space surrounded with the pair of glass panels and the body.
1. A method for manufacturing a glass panel unit, the method comprising an assembling step, an evacuation step, and a sealing step,
the assembling step including providing a glass panel unit assembly,
the glass panel unit assembly comprising:
a pair of glass substrates arranged to face each other;
a peripheral wall having a frame shape, containing a first sealing material having a first softening point and disposed between the pair of glass substrates;
a partition containing a second sealing material having a second softening point that is higher than the first softening point and partitioning an internal space, surrounded with the pair of glass substrates and the peripheral wall, into a first space and a second space;
a reinforcing wall containing a third sealing material having a third softening point that is higher than the first softening point, the reinforcing wall being adjacent to the peripheral wall in the internal space;
an air passage connecting the first space and the second space together; and
an evacuation port connecting the second space to an external environment, the reinforcing wall covering an entire surface, facing the internal space, of the peripheral wall in a plan view,
the evacuation step including evacuating the first space through the air passage, the second space, and the evacuation port,
the sealing step including heating the partition to a temperature equal to or higher than the second softening point to deform the partition and thereby close the air passage,
the method further comprising a bonding step to be performed before the sealing step,
the bonding step including heating and once melting the peripheral wall at a melting temperature to hermetically bond the pair of glass substrates together with the peripheral wall,
the melting temperature being set at a temperature equal to or higher than the first softening point and lower than the second softening point and the third softening point,
the method further comprising a removing step to be performed after the sealing step,
the removing step being the step of removing a part having the second space from a part having the first space to obtain the part having the first space as the glass panel unit,
after the removing step, in the glass panel unit, the reinforcing portion covering an entire surface, facing the first space, of the peripheral wall in a plan view, and the reinforcing portion not covering a surface, facing the first space, of the partition in a plan view.
2. The method of claim 1 , wherein
the melting temperature is closer to the second softening point or the third softening point than to the first softening point.