Non-alkali glass and method for producing same

1. 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 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 5 to 9.5,

CaO 4 to 11,

SrO 0.5 to 4.5,

BaO 0 to 0.5 and

ZrO 2 0 to 2,

wherein MgO+CaO+SrO+BaO is from exceeding 18.2 to 21,

MgO/(MgO+CaO+SrO+BaO) is 0.25 or more,

MgO/(MgO+CaO) is 0.3 or more,

MgO/(MgO+SrO) is 0.6 or more, and

Al 2 O 3 ×(MgO/(MgO+CaO+SrO+BaO)) is 5.5 or more.

2. The non-alkali glass according to claim 1 , having a glass transition point of 760° 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 770° 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, and 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 7 to 9.5,

CaO 4.5 to 8,

SrO 3 to 4.5,

BaO 0 to 0.1 and

ZrO 2 0 to 1,

wherein MgO+CaO+SrO+BaO is from 18.2 to 20,

MgO/(MgO+CaO+SrO+BaO) is 0.4 or more,

MgO/(MgO+CaO) is 0.55 or more,

MgO/(MgO+SrO) is 0.63 or more, and

Al 2 O 3 ×(MgO/(MgO+CaO+SrO+BaO)) is 5.75 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, and 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 7 to 9.5,

CaO 5 to 8,

SrO 3 to 4.5,

substantially no BaO and

substantially no ZrO 2 ,

wherein MgO+CaO+SrO+BaO is from exceeding 18.2 to 20,

MgO/(MgO+CaO+SrO+BaO) is 0.45 or more,

MgO/(MgO+CaO) is 0.6 or more,

MgO/(MgO+SrO) is 0.65 or more, and

Al 2 O 3 ×(MgO/(MgO+CaO+SrO+BaO)) is 6 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, 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, 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.