Provided is a glass fiber having a low spinning temperature and a low liquidus temperature, and besides, having a large difference between the liquidus temperature and the spinning temperature, and a method of manufacturing the same. The glass fiber of the present invention includes as a glass composition, in terms of mass % on an oxide basis, 50% to 65% of SiO.sub.2, 0% to 3% of Al.sub.2O.sub.3, 0% to 1% of MgO, 0% to less than 0.7% of CaO, 0% to 1% of Li.sub.2O, 10% to 20% of Na.sub.2O, 0% to 2% of K.sub.2O, 6% to 10% of TiO.sub.2, and 15% to 20% of ZrO.sub.2, and has a value for (Na.sub.2O+K.sub.2O)/(MgO+CaO) of 6.0 or more.

A provided glass composition includes, in mass %: 50≤SiO.sub.2≤65; 20≤B.sub.2O.sub.3≤30; and 5≤Al.sub.2O.sub.3≤20, and further includes: at least one selected from the group consisting of MgO and CaO; and at least one selected from the group consisting of Li.sub.2O, Na.sub.2O, and K.sub.2O. In the glass composition, 0.1≤(MgO+CaO)<5, 0≤(Li.sub.2O+Na.sub.2O+K.sub.2O)≤4, and 0.50<MgO/(MgO+CaO)≤1.00 are satisfied. The glass composition is suitable for manufacturing a glass filler that has a low permittivity and that can exhibit an excellent water resistance.

Provided is a glass composition for glass fiber having a low dielectric constant and a low dielectric loss tangent, suppressing occurrence of phase separation, and reducing viscosity at high temperatures. The glass composition for glass fiber includes: SiO.sub.2 in the range of 52.0 to 59.5% by mass; B.sub.2O.sub.3 in the range of 17.5 to 25.5% by mass; Al.sub.2O.sub.3 in the range of 9.0 to 14.0% by mass; SrO in the range of 0.5 to 6.0% by mass; MgO in the range of 1.0 to 5.0% by mass; and CaO in the range of 1.0 to 5.0% by mass, and includes F.sub.2 and Cl.sub.2 in the range of 0.1 to 2.5% by mass in total, with respect to the total amount.

Provided is a glass composition for glass fiber having a low dielectric constant and a low dielectric loss tangent, suppressing occurrence of phase separation, and reducing viscosity at high temperatures. The glass composition for glass fiber includes: SiO.sub.2 in the range of 52.0 to 59.5% by mass; B.sub.2O.sub.3 in the range of 17.5 to 25.5% by mass; Al.sub.2O.sub.3 in the range of 9.0 to 14.0% by mass; SrO in the range of 0.5 to 6.0% by mass; MgO in the range of 1.0 to 5.0% by mass; and CaO in the range of 1.0 to 5.0% by mass, and includes F.sub.2 and Cl.sub.2 in the range of 0.1 to 2.5% by mass in total, with respect to the total amount.

Provided is a novel glass filler having a low permittivity. The glass filler provided includes a glass composition, wherein the glass composition includes, in wt %:95≤SiO.sub.2≤99.5; 0≤B.sub.2O.sub.3≤2; 0.01≤Al.sub.2O.sub.3≤4; 0≤R.sub.2O≤4; 0.01≤RO ≤4; and 0≤TiO.sub.2≤4, where RO is at least one selected from MgO, CaO, SrO, and ZnO, and R.sub.2O is at least one selected from Li.sub.2O, Na.sub.2O, and K.sub.2O. This glass filler can have a permittivity of less than 4 at 1 GHz.

Disclosed herein are methods for forming low melting point glass fibers comprising providing a glass feedstock comprising a low melting point glass and melt-spinning the glass feedstock to produce glass fibers, wherein the glass transition temperature of the glass fibers is less than or equal to about 120% of the glass transition temperature of the glass feedstock. The disclosure also relates to method for forming low melting point glass frit further comprising jet-milling the glass fibers. Low melting point glass frit and fibers produced by the methods described above are also disclosed herein.

Disclosed herein are methods for forming low melting point glass fibers comprising providing a glass feedstock comprising a low melting point glass and melt-spinning the glass feedstock to produce glass fibers, wherein the glass transition temperature of the glass fibers is less than or equal to about 120% of the glass transition temperature of the glass feedstock. The disclosure also relates to method for forming low melting point glass frit further comprising jet-milling the glass fibers. Low melting point glass frit and fibers produced by the methods described above are also disclosed herein.

A thermal insulation material includes inorganic fibers and an endothermic material dispersed throughout the inorganic fibers. The endothermic material may be incorporated into the inorganic fibers during a fiber attenuation process. The endothermic material may be particles entangled within a web of the inorganic fibers or may be coated onto surfaces of the inorganic fibers.

A thermal insulation material includes inorganic fibers and an endothermic material dispersed throughout the inorganic fibers. The endothermic material may be incorporated into the inorganic fibers during a fiber attenuation process. The endothermic material may be particles entangled within a web of the inorganic fibers or may be coated onto surfaces of the inorganic fibers.

Glass compositions suitable for fiber forming having low levels of Li.sub.2O and glass fibers having high-modulus are disclosed. The glass composition may include SiO.sub.2 from about 59 to about 63 weight percent, Al.sub.2O.sub.3 from about 13.7 to about 16 weight percent, CaO from about 14 to about 16.5 weight percent, MgO from about 6 to about 8.5 weight percent, Fe.sub.2O.sub.3 less than 1 weight percent, and TiO.sub.2 less than 1 weight percent. In some cases, the composition may be substantially free of Li.sub.2O. In some cases, the composition may include Li.sub.2O up to 0.5 weight percent. In some cases, RE.sub.2O.sub.3 may be present in the composition in an amount up to 1.5 weight percent. The glass compositions can be used to form glass fibers which can be incorporated into a variety of other fiber glass products (e.g., strands, rovings, fabrics, etc.) and incorporated into various composites.