Glass plate, process for producing it, and process for producing TFT panel
View Patent ↗To provide a glass plate which has a low B 2 O 3 content and which can be used as a glass plate for e.g. an LCD panel. A glass plate which comprises, as a glass matrix composition as represented by mass % based on oxide, from 53 to 74 mass % of SiO 2 , from 15 to 23 mass % of Al 2 O 3 , from 0 to 3 mass % of B 2 O 3 , from 2 to 17 mass % of MgO, from 0 to 12 mass % of CaO, from 0 to 6 mass % of SrO, from 6 to 28 mass % of MgO+CaO+SrO, from 0 to 9 mass % of Na 2 O, from 0 to 6 mass % of K 2 O and from 0.8 to 11 mass % of Na 2 O+K 2 O, contains from 100 to 500 ppm of SO 3 , has an average coefficient of thermal expansion from 50 to 350° C. of at most 60×10 −7 /° C., and has a strain point of at least 600° C.
1. A glass plate which comprises, as a glass matrix composition as represented by mass % based on oxide:
SiO 2
53 to 74,
Al 2 O 3
15 to 23,
B 2 O 3
0 to 3,
MgO
2 to 17,
CaO
0 to 12,
SrO
0 to 6,
MgO + CaO + SrO
6 to 28,
Na 2 O
0 to 9,
K 2 O
0 to 6,
Na 2 O + K 2 O
0.8 to 11,
wherein said glass plate comprises from 100 to 500 ppm of SO 3 , has an average coefficient of thermal expansion from 50 to 350° C. of at most 60×10 −7 /° C., has a strain point of at least 600° C., and has a heat shrinkage (C) of at most 20 ppm.
2. The glass plate according to claim 1 , wherein the amount of Na 2 O+K 2 O is at most 9%, as represented by mass % based on oxide.
3. The glass plate according to claim 1 , further comprising as represented by mass % based on oxide, Li 2 O in an amount of from 0-5%.
4. The glass plate according to claim 1 , further comprising as represented by mass % based on oxide, Na 2 O+K 2 O+Li 2 O in an amount of from 1 to 9%.
5. A process for producing a glass plate, which comprises blending starting materials so as to obtain glass comprising as a glass matrix composition as represented by mass % based on oxide:
SiO 2
53 to 74,
Al 2 O 3
15 to 23,
B 2 O 3
0 to 3,
MgO
2 to 17,
CaO
0 to 12,
SrO
0 to 6,
MgO + CaO + SrO
6 to 28,
Na 2 O
0 to 9,
K 2 O
0 to 6, and
Na 2 O + K 2 O
0.8 to 11
adding a sulfate in an amount of from 0.05 to 1.0 mass % as calculated as SO 3 to 100 mass % of the starting materials to obtain a glass material, melting the glass material and forming the molten glass material into plate glass to obtain the glass plate as defined in claim 1 .
6. A process for producing a glass plate, which comprises forming molten glass obtained by melting starting materials into a glass plate in a ribbon shape in a float process furnace, and cooling the glass plate by a cooling means to obtain the glass plate as defined in claim 1 in a room temperature state, wherein the cooling means is a cooling means which fulfils an average cooling rate represented by (T H −T L )/t of from 10 to 300° C./min, where T H (° C.) is the surface temperature of the glass plate withdrawn from the float process furnace, T L (° C.) is the room temperature, and t (min) is the time over which the surface temperature of the glass plate cooled by the cooling means drops from T H to T L .
7. A process for producing a TFT panel, which comprises a film forming step of forming an array substrate gate insulating film on the surface of a glass plate and a bonding step of bonding the array substrate and a color filter substrate, wherein the film forming step is a step of increasing the 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.
8. The glass plate according to claim 1 , which contains substantially no B 2 O 3 , comprises as a glass matrix composition as represented by mass % based on oxide:
SiO 2
53 to 74,
Al 2 O 3
15 to 23,
MgO
2 to 17,
CaO
0 to 12,
SrO
0 to 6,
MgO + CaO + SrO
10 to 28,
Na 2 O
0 to 9,
K 2 O
0 to 6,
Na 2 O + K 2 O
0.8 to 9,
wherein said glass plate comprises from 100 to 500 ppm of SO 3 , and has a strain point of at least 650° C.
9. The glass plate according to claim 8 , which contains substantially no B 2 O 3 , comprises as a glass matrix composition as represented by mass % based on oxide:
SiO 2
58 to 67,
Al 2 O 3
15 to 21,
MgO
4 to 14,
CaO
0 to 5,
SrO
0 to 3,
MgO + CaO + SrO
10 to 19,
Na 2 O
1 to 9,
K 2 O
0 to 5,
Na 2 O + K 2 O
1 to 9,
wherein said glass plate comprises from 100 to 500 ppm of SO 3 , and has a heat shrinkage (C) of at most 20 ppm.
10. A process for producing a glass plate, which comprises blending starting materials so as to obtain glass containing substantially no B 2 O 3 and comprising as a glass matrix composition as represented by mass % based on oxide:
SiO 2
58 to 67,
Al 2 O 3
15 to 21,
MgO
4 to 14,
CaO
0 to 5,
SrO
0 to 3,
MgO + CaO + SrO
10 to 19,
Na 2 O
1 to 9,
K 2 O
0 to 5, and
Na 2 O + K 2 O
1 to 9
adding a sulfate in an amount of from 0.05 to 1.0 mass % as calculated as SO 3 to 100 mass % of the starting materials to obtain a glass material, melting the glass material and forming the molten glass material into plate glass to obtain the glass plate as defined in claim 9 .
11. A process for producing a glass plate, which comprises blending starting materials so as to obtain glass containing substantially no B 2 O 3 and comprising as a glass matrix composition as represented by mass % based on oxide:
SiO 2
53 to 74,
Al 2 O 3
15 to 23,
MgO
2 to 17,
CaO
0 to 12,
SrO
0 to 6,
MgO + CaO + SrO
10 to 28,
Na 2 O
0 to 9,
K 2 O
0 to 6, and
Na 2 O + K 2 O
0.8 to 9
adding a sulfate in an amount of from 0.05 to 1.0 mass % as calculated as SO 3 to 100 mass % of the starting materials to obtain a glass material, melting the glass material and forming the molten glass material into plate glass to obtain the glass plate as defined in claim 8 .
12. The glass plate according to claim 1 , which comprises as a glass matrix composition as represented by mass % based on oxide:
SiO 2
58 to 67,
Al 2 O 3
15 to 21,
B 2 O 3
0 to 3,
MgO
4 to 14,
CaO
0 to 5,
SrO
0 to 3,
MgO + CaO + SrO
6 to 19,
Na 2 O
1 to 9,
K 2 O
0 to 5,
Na 2 O + K 2 O
1 to 11,
wherein said glass plate comprises from 100 to 500 ppm of SO 3 , and has a heat shrinkage (C) of at most 20 ppm.
13. A process for producing a glass plate, which comprises blending starting materials so as to obtain glass comprising as a glass matrix composition as represented by mass % based on oxide:
SiO 2
58 to 67,
Al 2 O 3
15 to 21,
B 2 O 3
0 to 3,
MgO
4 to 14,
CaO
0 to 5,
SrO
0 to 3,
MgO + CaO + SrO
6 to 19,
Na 2 O
1 to 9,
K 2 O
0 to 5, and
Na 2 O + K 2 O
1 to 11
adding a sulfate in an amount of from 0.05 to 1.0 mass % as calculated as SO 3 to 100 mass % of the starting materials to obtain a glass material, melting the glass material and forming the molten glass material into plate glass to obtain the glass plate as defined in claim 12 .