Non-alkali glass and method for producing same
View Patent ↗The present invention relates to a non-alkali glass having a strain point of from 710° C. to lower than 725° C., an average thermal expansion coefficient at from 50 to 300° C. of from 30×10 −7 to 43×10 −7 /° C., a temperature T 2 at which glass viscosity reaches 10 2 dPa·s of 1710° C. or lower, a temperature T 4 at which the glass viscosity reaches 10 4 dPa·s of 1320° C. or lower, and containing, indicated by mol % on the basis of oxides, SiO 2 66 to 70, Al 2 O 3 12 to 14, B 2 O 3 exceeding 0 to 1.5, MgO exceeding 9.5 to 13 (or 5 to 9.5), CaO 4 to 9 (or 4 to 11), SrO 0.5 to 4.5, BaO 0 to 0.5 and ZrO 0 to 2.
1. A non-alkali glass having a strain point of from 710° C. to lower than 725° C., a glass transition point of 780° C. or higher, an average thermal expansion coefficient at from 50 to 300° C. of from 30×10 −7 to 43×10 −7 /° C., a temperature T 2 at which glass viscosity reaches 10 2 dPa·s of 1710° C. or lower, a temperature T 4 at which the glass viscosity reaches 10 4 dPa·s of 1320° C. or lower,
the non-alkali glass comprising, indicated by mol % on the basis of oxides:
SiO 2
66 to 70,
Al 2 O 3
12 to 14,
B 2 O 3
exceeding 0 to 1.5,
MgO
exceeding 9.5 to 12,
CaO
4 to 9,
SrO
0.5 to 4.5,
BaO
0 to 0.5 and
ZrO 2
0 to 2,
wherein MgO+CaO+SrO+BaO is from 17 to 21,
MgO/(MgO+CaO+SrO+BaO) is 0.4 or more,
MgO/(MgO+CaO) is 0.4 or more, and
MgO/(MgO+SrO) is 0.6 or more.
2. The non-alkali glass according to claim 1 , having a glass transition point of 780° C. or higher, a specific gravity of 2.65 or less, a Young's modulus of 84 GPa or more, a devitrification temperature of 1340° C. or lower, a photoelastic constant of from 25 to 29 nm/MPa/cm, and a dielectric constant of 5.8 to 6.5.
3. The non-alkali glass according to claim 1 , having a glass transition point of 780° C. or higher, a specific gravity of 2.62 or less, a Young's modulus of 84 GPa or more, a devitrification temperature of 1330° C. or lower, a photoelastic constant of from 25 to 29 nm/MPa/cm, and a dielectric constant of 5.8 to 6.5.
4. The non-alkali glass according to claim 1 , having the strain point of from 710° C. to lower than 725° C., the average thermal expansion coefficient at from 50 to 300° C. of from 35×10 −7 to 42×10 −7 /° C., the temperature T 2 at which glass viscosity reaches 10 2 dPa·s of 1690° C. or lower, the temperature T 4 at which the glass viscosity reaches 10 4 dPa·s of 1315° C. or lower,
the non-alkali glass comprising, indicated by mol % on the basis of oxides:
SiO 2
66 to 69,
Al 2 O 3
12 to 13.5,
B 2 O 3
0.4 to 1.4,
MgO
exceeding 9.5 to 11.5,
CaO
4 to 8,
SrO
2 to 4.5,
BaO
0 to 0.1 and
ZrO 2
0 to 0.5,
wherein MgO+CaO+SrO+BaO is from 17 to 20,
MgO/(MgO+CaO+SrO+BaO) is 0.4 or more,
MgO/(MgO+CaO) is 0.55 or more, and
MgO/(MgO+SrO) is 0.63 or more.
5. The non-alkali glass according to claim 1 , having the strain point of from 710° C. to lower than 725° C., the average thermal expansion coefficient at from 50 to 300° C. of from 35×10 −7 to 41×10 −7 /° C., the temperature T 2 at which glass viscosity reaches 10 2 dPa·s of 1690° C. or lower, the temperature T 4 at which the glass viscosity reaches 10 4 dPa·s of 1310° C. or lower,
the non-alkali glass comprising, indicated by mol % on the basis of oxides:
SiO 2
66.5 to 68,
Al 2 O 3
12.5 to 13.5,
B 2 O 3
0.4 to 1.3,
MgO
exceeding 9.5 to 11.5,
CaO
5 to 8,
SrO
2 to 4.5,
substantially no BaO and
substantially no ZrO 2 ,
wherein MgO+CaO+SrO+BaO is from 18 to 20,
MgO/(MgO+CaO+SrO+BaO) is 0.45 or more,
MgO/(MgO+CaO) is 0.55 or more, and
MgO/(MgO+SrO) is 0.65 or more.
6. A method for producing the non-alkali glass described in claim 1 , wherein silica sand having a median particle size D 50 of from 20 to 27 μm, a ratio of particles having a particle size of 2 μm or less of 0.3% by volume or less and a ratio of particles having a particle size of 100 μm or more of 2.5% by volume or less is used as a silicon source of a SiO 2 raw material.
7. A method for producing the non-alkali glass described in claim 1 , wherein an alkaline earth metal source containing a hydroxide of an alkaline earth metal in an amount of from 15 to 100 mol % (in terms of MO, provided that M is an alkaline earth metal element, hereinafter the same), of 100 mol % (in terms of MO) of the alkaline earth metal source is used as the alkaline earth metal source of MgO, CaO, SrO and BaO.
8. A method for producing the non-alkali glass described in claim 1 , wherein silica sand having a median particle size D 50 of from 20 to 27 μm, a ratio of particles having a particle size of 2 μm or less of 0.3% by volume or less and a ratio of particles having a particle size of 100 μm or more of 2.5% by volume or less is used as a silicon source of a SiO 2 raw material, and an alkaline earth metal source containing a hydroxide of an alkaline earth metal in an amount of from 15 to 100 mol % (in terms of MO, provided that M is an alkaline earth metal element, hereinafter the same), of 100 mol % (in terms of MO) of the alkaline earth metal source is used as the alkaline earth metal source of MgO, CaO, SrO and BaO.