Glass composition for glass fiber, glass fiber, and glass fiber sheet

1. A glass fiber, comprising a glass composition comprising, in terms of oxides by mass %, 45 to 65% of SiO 2 , 10 to 20% of Al 2 O 3 13 to 25% of B 2 O 3 , 5.5 to 9% of MgO, 0 to 10% of CaO, 0 to 1% of Li 2 O+Na 2 O+K 2 O, SrO, and BaO,

wherein the glass composition has a temperature Ty of less than 1300° C. at 10 3.0 dPa·s, and

wherein the glass fiber has an average diameter of 3 to 7.2 μm.

2. The glass fiber according to claim 1 , wherein the glass composition further comprises 0.01 to 5.0% of CeO 2 in terms of oxides by mass %.

3. The glass fiber according to claim 1 , wherein a content of SrO is 0.1 to 10% and a content of BaO is 0.1 to 10% in terms of oxides by mass %.

4. The glass fiber according to claim 1 , wherein a total content of alkaline-earth metal oxides including MgO, CaO, SrO, and BaO is 10 to 25% in terms of oxides by mass %, and a value obtained by dividing a total content of SrO and BaO by the total content of the alkaline-earth metal oxides is in a range of 0.15 to 0.50.

5. The glass fiber according to claim 1 , wherein the glass composition has a dielectric constant of 6.0 or less and a dielectric dissipation factor of 20×10 −4 or less at a frequency of 1 MHz.

6. The glass fiber according to claim 1 , wherein the glass composition has a dielectric constant of 6.0 or less and a dielectric dissipation factor of 100×10 −4 or less at a frequency of 10 GHz.

7. The glass fiber according to claim 1 , which is used for forming an organic resin composite material by forming the glass fiber into a glass cloth or a non-woven fabric and combining it with an organic resin material.

8. A glass fiber sheet, comprising the glass fiber of according to claim 1 , the glass fiber sheet being combined with an organic resin material to form an organic resin composite material.

9. The glass fiber sheet according to claim 8 , wherein the glass fiber sheet is a glass cloth or glass paper.