Glass plate for display panels, process for producing it, and process for producing TFT panel

1. A glass plate comprising:

as a glass matrix composition comprising, as represented by mass % based on oxide:

SiO 2 65.0 to 73.0,

Al 2 O 3 6.0 to 15.0,

B 2 O 3 0 to 1.0,

MgO 5.0 to 9.0,

CaO 0 to less than 2.0,

SrO 0 to 1.0,

BaO 0 to 1.0,

MgO+CaO+SrO+BaO 6.5 to 10.0,

Li 2 O 0 to 1.0,

Na 2 O 3.0 to 17.0,

K 2 O 0 to 12.0, and

Li 2 O+Na 2 O+K 2 O 10.0 to 18.0,

wherein the glass plate has a heat shrinkage (C) of at most 15 ppm and a density of at most 2.46 g/cm 3 .

2. A process for producing a glass plate, which comprises:

melting a starting material to obtain a molten glass;

forming the molten glass into a glass plate of a ribbon shape in a float process furnace; and

cooling the glass plate by a cooling device to obtain the glass plate as defined in claim 1 in a room temperature state,

wherein the cooling device is configured to fulfill an average cooling rate represented by (T H −T L )/t of from 10 to 300° C./min, where T H (° C.) is a surface temperature of the glass plate withdrawn from the float process furnace, T L (° C.) is a room temperature, and t (min) is a time over which the surface temperature of the glass plate cooled by the cooling device drops from T H to T L .

3. A process for producing a TFT panel, which comprises:

a gate insulating film of an array substrate on a surface of a glass plate; and

bonding the array substrate and a color filter substrate,

wherein the forming of the gate insulating film comprises increasing a temperature of a film forming region on the surface of the glass plate as defined in claim 1 to a film forming temperature within a range of from 150 to 300° C., and holding the glass plate at the film forming temperature for from 5 to 60 minutes to form the gate insulating film on the film forming region.

4. The glass plate of claim 1 , wherein the glass matrix composition comprises CaO in an amount of from 0 to 1.0%.

5. The glass plate of claim 1 , wherein a total content of MgO, CaO, SrO and BaO in the glass matrix composition is from 7.0 to 8.0%.

6. The glass plate of claim 1 , wherein the glass plate has the heat shrinkage (C) of at most 10 ppm.

7. A glass plate comprising:

a glass matrix composition comprising, as represented by mass % based on oxide:

SiO 2 50.0 to 65.0,

Al 2 O 3 16.0 to 20.0,

B 2 O 3 0 to 1.0,

MgO 4.2 to 8.0,

CaO 2 to 6.0,

SrO 0 to 1.0,

BaO 0 to 1.0,

MgO+CaO+SrO+BaO 6.5 to 11.0,

Li 2 O 0 to 1.0,

Na 2 O 2.0 to 12.0,

K 2 O 0 to 12.0,

Li 2 O+Na 2 O+K 2 O 8.0 to 17.0,

wherein the glass plate has a heat shrinkage (C) of at most 20 ppm and an average coefficient of thermal expansion from 50 to 350° C. of at most 83×10 −7 /° C.

8. The glass plate of claim 7 , wherein the glass matrix composition comprises Al 2 O 3 in an amount of from 17.0 to 19.0%.

9. A process for producing a glass plate, which comprises:

melting a starting material to obtain a molten glass;

forming the molten glass into a glass plate of a ribbon shape in a float process furnace; and

cooling the glass plate by a cooling device to obtain the glass plate as defined in claim 7 in a room temperature state,

wherein the cooling device is configured to fulfill an average cooling rate represented by (T H −T L )/t of from 10 to 300° C./min, where T H (° C.) is a surface temperature of the glass plate withdrawn from the float process furnace, T L (° C.) is a room temperature, and t (min) is a time over which the surface temperature of the glass plate cooled by the cooling device drops from T H to T L .

10. A process for producing a TFT panel, which comprises:

forming a gate insulating film of an array substrate on a surface of a glass plate; and

bonding the array substrate and a color filter substrate,

wherein the forming of the gate insulating film comprises increasing a temperature of a film forming region on the surface of the glass plate as defined in claim 7 to a film forming temperature within a range of from 150 to 300° C., and holding the glass plate at the film forming temperature for from 5 to 60 minutes to form the gate insulating film on the film forming region.