Low dielectric glass composition, fiber and article

Abstract

Provided are glass compositions and glass fibers having low dielectric constants and low loss factors that may be suitable for use in electronic applications and articles. The glass fibers and compositions may include 48.0 to 58.0 weight percent SiO2, 15.0 to 26.0 weight percent B2O3, 12.0 to 18.0 weight percent Al2O3, greater than 0.25 to 3.0 weight percent P2O5, greater than 0.25 to 7.00 weight percent CaO, 5.0 weight percent or less MgO, greater than 0 to 1.5 weight percent SnO2, and 6.0 weight percent or less TiO2. Furthermore, the glass compositions have a glass viscosity of 1000 poise at temperatures above 1350°C and a liquidus temperature above 1000°C.

Description

[Technical Field]

[0001] [Related Applications] This application claims the benefit of priority under PCT Article 8 of U.S. Patent Application No. 16 / 732,825, filed January 2, 2020, and U.S. Patent Application No. 16 / 792,658, filed February 17, 2020. These applications are continuation-in-part of U.S. Patent Application No. 16 / 474,287, filed June 27, 2019, which is a national stage application of International Application No. PCT / US17 / 67785, filed December 21, 2017, which claims priority to U.S. Patent Application No. 62 / 439,755, filed December 28, 2016. The contents of the above applications are incorporated herein by reference as if fully set forth in their entireties.

[0002] The present invention relates to glass compositions and fibers. More particularly, the present invention relates to glass compositions and fibers having a low dielectric constant and a low loss factor. Furthermore, the glass fibers of the present invention are preferably suitable for use in connection with electronic devices, such as for reinforcing printed circuit laminates and the like. [Background technology]

[0003] Modern electronic devices typically comprise printed circuit boards reinforced with glass fibers. Many modern electronic devices, such as mobile or fixed wireless telephones, computers, smartphones, tablets, etc., have electronic systems that operate at high processing speeds and high or very high frequencies. When glass is exposed to such high or very high frequency electromagnetic fields, the glass absorbs at least a portion of the energy and converts the absorbed energy into heat. The energy converted into heat by the glass is called dielectric loss energy. This dielectric loss energy is proportional to the "dielectric constant" and "dielectric loss tangent" of the glass composition, as shown by the following equations: W=k f v 2 ε (tan δ)

[0004] In the above formula, "W" is the dielectric loss energy in the glass, "k" is a constant, "f" is the frequency, and "v" is the 2 " is the potential gradient, "ε" is the dielectric constant, and "tan δ" is the dielectric loss tangent. The dielectric loss tangent (tan δ) is dimensionless and is often referred to in the art by the following synonyms: "loss factor" or more commonly "loss factor" (Df). As the above equation shows, the dielectric loss energy "W" increases with increasing dielectric constant and dielectric loss tangent (loss factor, Df) of the glass and / or with increasing frequency.

[0005] Two types of glass fibers commonly used to reinforce printed circuit boards are E-glass and D-glass. However, E-glass has a relatively high dielectric constant in the range of about 6.1 at room temperature and a dielectric constant of about 38×10 -4 D-glass has a relatively high loss factor in the range of 0.01 to 0.01. Therefore, E-glass can have relatively high dielectric loss, making it an insufficient reinforcing material for printed circuit boards with higher electronic component densities and higher processing speeds. D-glass, on the other hand, has a relatively low dielectric constant and loss factor. However, D-glass has a relatively high melting temperature, relatively poor processability, relatively poor mechanical performance, and relatively poor water resistance. In addition, D-glass can have poor adhesion to epoxy resins and commonly exhibits defects in the form of striae and bubbles. Therefore, neither E-glass nor D-glass is ideally suited for use as a reinforcing fiber in high-speed printed circuit boards, and neither is well suited for circuit boards operating at high or ultra-high frequencies, from about 100 MHz to about 18 GHz.

[0006] Prior attempts to provide glass formulations suitable for electronic devices include U.S. Patent No. 6,294,496 to Mori, U.S. Patent No. 6,294,496 to Creux, U.S. Patent No. 6,294,496 to Tamura ... Kuhn, U.S. Patent No. 6,294,496 to Yoshida, U.S. Patent No. 6,294,496 to Sawanoi, and U.S. Patent No. 6,294,496 to Zhang. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 5,958,808 [Patent Document 2] U.S. Patent Application Publication No. 2004 / 01755557 [Patent Document 3] U.S. Patent No. 6,309,990 [Patent Document 4] U.S. Patent No. 6,846,761 [Patent Document 5] International Publication No. 2010 / 011701 [Patent Document 6] U.S. Patent Application Publication No. 2011 / 0281484 [Patent Document 7] U.S. Patent No. 8,679,993 [Patent Document 8] Chinese Patent Application Publication No. 103351102 Summary of the Invention

[0008] In one aspect of the invention, there is provided a glass composition comprising 48.0 weight percent to 58.0 weight percent SiO, 15.0 weight percent B0 to 26.0 weight percent B0, 12.0 weight percent Al0 to 18.0 weight percent Al0, greater than 0.25 weight percent to 3.0 weight percent P0, greater than 0.25 weight percent to 7.0 weight percent CaO, less than or equal to 5.0 weight percent MgO, consisting essentially of greater than 0 weight percent to 1.5 weight percent Sn0, and less than or equal to 6.0 weight percent Ti0, having a glass viscosity of 1000 poise at a temperature greater than 1350°C, and having a liquidus temperature greater than 1000°C, where "consisting essentially of," as used elsewhere herein, applies only to the Sn0 component of the formulation.

[0009] In one embodiment of the present invention, the glass composition further comprises 49.0 weight percent to 57.5 weight percent SiO2, further comprises 15.5 weight percent to 25.5 weight percent B2O3, further comprises 12.5 weight percent to 17.50 weight percent Al2O3, further comprises more than 0.25 weight percent to 3.0 weight percent P2O5, further comprises more than 0.25 weight percent to 6.5 weight percent CaO, further comprises 4.5 weight percent or less MgO, consists essentially of more than 0 weight percent to 1.25 weight percent SnO2, and further comprises 5.5 weight percent or less TiO2.

[0010] In one embodiment of the present invention, the glass composition further comprises 50.0 weight percent to 57.0 weight percent SiO2, further comprises 16.0 weight percent to 25.0 weight percent B2O3, further comprises 13.0 weight percent to 17.0 weight percent Al2O3, further comprises more than 0.25 weight percent to 3.0 weight percent P2O5, further comprises more than 0.25 weight percent to 6.0 weight percent CaO, further comprises 4.0 weight percent or less MgO, consists essentially of more than 0 weight percent to 1.0 weight percent SnO2, and further comprises 5.0 weight percent or less TiO2.

[0011] In one embodiment of the invention, the composition further comprises one or more of: greater than or equal to 49.0 weight percent SiO2, less than or equal to 57.5 weight percent SiO2, greater than or equal to 15.5 weight percent B2O3, less than or equal to 25.5 weight percent B2O3, greater than or equal to 12.5 weight percent Al2O3, less than or equal to 17.50 weight percent Al2O3, greater than 0.25 weight percent P2O5, less than or equal to 3.0 weight percent P2O5, greater than 0.25 weight percent CaO, less than or equal to 6.5 weight percent CaO, less than or equal to 4.5 weight percent MgO, greater than 0 weight percent SnO2, less than or equal to 1.25 weight percent SnO2, and / or less than or equal to 5.5 weight percent TiO2.

[0012] In one embodiment of the present invention, the composition comprises 50.0 weight percent or more of SiO2 , 57.0 weight percent or less SiO2, 16.0 weight percent or more B2O3, 25.0 weight percent or less B2O3, 13.0 weight percent or more Al2O3, 17.0 weight percent or less Al2O3, greater than 0.25 weight percent P2O5, 3.0 weight percent or less P2O5, greater than 0.25 weight percent CaO, 6.0 weight percent or less CaO, 4.0 weight percent or less MgO, greater than 0 weight percent SnO2, 1.0 weight percent or less SnO2, and / or 5.0 weight percent or less TiO2.

[0013] In one embodiment of the present invention, the composition has a liquidus temperature above 1000°C.

[0014] In one embodiment of the present invention, the composition has a liquidus temperature above 1050°C.

[0015] In one embodiment of the present invention, the composition has a liquidus temperature above 1100°C.

[0016] In one embodiment of the present invention, the composition has a glass viscosity of 1000 poise at temperatures above 1355°C.

[0017] In one embodiment of the present invention, the composition has a glass viscosity of 1000 poise at temperatures above 1360°C.

[0018] In one embodiment of the present invention, the glass fibers are formed from the glass composition described above.

[0019] In one embodiment of the present invention, the glass fiber has a dielectric constant of less than 6 and / or a dielectric constant of 38×10 at a frequency of 10 GHz at room temperature. -4 It has the following loss factors:

[0020] In one embodiment of the present invention, the glass fiber has a dielectric constant of 4.80 or less at room temperature and a frequency of 10 GHz and / or a dielectric constant of 30×10 -4 It has the following loss factors:

[0021] In one embodiment of the present invention, the glass fiber has a dielectric constant of less than 4.70 at room temperature and a frequency of 10 GHz and / or a dielectric constant of less than 28×10 -4 It has the following loss factors:

[0022] In one embodiment of the present invention, the glass composition crystallizes into and is prone to form aluminoborate mullite crystals as the primary devitrification phase. It has a unique network structure.

[0023] In one embodiment of the present invention, there is provided a method for providing a continuous, producible, low dielectric glass fiber, comprising the steps of: feeding any of the glass compositions described herein into a melting zone of a glass melting furnace; heating the composition to a forming temperature above the liquidus temperature; and continuously spinning the molten glass to produce a glass fiber with a low dielectric constant and low loss factor.

[0024] In one embodiment of the present invention, there is further provided a low dielectric glass fiber formed from a glass composition comprising 48.0 weight percent to 58.0 weight percent SiO2, 15.0 weight percent to 26.0 weight percent B2O3, 12.0 weight percent to 18.0 weight percent Al2O3, more than 0.25 weight percent to 3.0 weight percent P2O5, more than 0.25 weight percent to 7.00 weight percent CaO, 5.0 weight percent or less MgO, greater than 0 weight percent to 1.5 weight percent SnO2, and 6.0 weight percent or less TiO2, and having a glass viscosity of 1000 poise at a temperature above 1350°C, and a liquidus temperature above 1000°C.

[0025] In one embodiment of the present invention, the glass composition further comprises 49.0 weight percent to 57.5 weight percent SiO2, further comprises 15.5 weight percent to 25.5 weight percent B2O3, further comprises 12.5 weight percent to 17.50 weight percent Al2O3, further comprises more than 0.25 weight percent to 3.0 weight percent P2O5, further comprises more than 0.25 weight percent to 6.5 weight percent CaO, further comprises 4.5 weight percent or less MgO, consists essentially of more than 0 weight percent to 1.25 weight percent SnO2, and further comprises 5.5 weight percent or less TiO2.

[0026] In one embodiment of the present invention, the glass composition further comprises 50.0 weight percent to 57.0 weight percent SiO2, further comprises 16.0 weight percent to 25.0 weight percent B2O3, further comprises 13.0 weight percent to 17.0 weight percent Al2O3, further comprises more than 0.25 weight percent to 3.0 weight percent P2O5, further comprises more than 0.25 weight percent to 6.0 weight percent CaO, further comprises 4.0 weight percent or less MgO, consists essentially of more than 0 weight percent to 1.0 weight percent SnO2, and further comprises 5.0 weight percent or less TiO2.

[0027] In one embodiment of the invention, the composition further comprises one or more of: greater than or equal to 49.0 weight percent SiO2, less than or equal to 57.5 weight percent SiO2, greater than or equal to 15.5 weight percent B2O3, less than or equal to 25.5 weight percent B2O3, greater than or equal to 12.5 weight percent Al2O3, less than or equal to 17.50 weight percent Al2O3, greater than 0.25 weight percent P2O5, less than or equal to 3.0 weight percent P2O5, greater than 0.25 weight percent CaO, less than or equal to 6.5 weight percent CaO, less than or equal to 4.5 weight percent MgO, greater than 0 weight percent SnO2, less than or equal to 1.25 weight percent SnO2, and / or less than or equal to 5.5 weight percent TiO2.

[0028] In one embodiment of the invention, the composition further comprises one or more of: greater than or equal to 50.0 weight percent SiO2, less than or equal to 57.0 weight percent SiO2, greater than or equal to 16.0 weight percent B2O3, less than or equal to 25.0 weight percent B2O3, greater than or equal to 13.0 weight percent Al2O3, less than or equal to 17.0 weight percent Al2O3, greater than 0.25 weight percent P2O5, less than or equal to 3.0 weight percent P2O5, greater than 0.25 weight percent CaO, less than or equal to 6.0 weight percent CaO, less than or equal to 4.0 weight percent MgO, greater than 0 weight percent SnO2, less than or equal to 1.25 weight percent SnO2, and / or less than or equal to 5.0 weight percent TiO2.

[0029] In one embodiment of the present invention, the glass composition has a liquidus temperature above 1000°C.

[0030] In one embodiment of the present invention, the glass composition has a liquidus temperature above 1050°C.

[0031] In one embodiment of the present invention, the glass composition has a liquidus temperature above 1100°C.

[0032] In one embodiment of the present invention, the glass composition has a glass viscosity of 1000 poise at temperatures above 1355°C.

[0033] In one embodiment of the present invention, the glass composition has a glass viscosity of 1000 poise at temperatures above 1360°C.

[0034] In one embodiment of the present invention, the glass fiber has a dielectric constant of less than 6 and / or a dielectric constant of 38×10 at a frequency of 10 GHz at room temperature. -4 It has the following loss factors:

[0035] In one embodiment of the present invention, the glass fiber has a thermal conductivity of 4.8 at a frequency of 10 GHz at room temperature. Dielectric constant less than 0 and / or 30 x 10 -4 It has the following loss factors:

[0036] In one embodiment of the present invention, the glass fiber has a dielectric constant of less than 4.70 at room temperature and a frequency of 10 GHz and / or a dielectric constant of less than 28×10 -4 It has the following loss factors:

[0037] In one embodiment of the present invention, the glass fibers are formed from a glass composition that has an inherent network structure that is prone to crystallizing and forming aluminoborate mullite crystals as the first devitrified phase.

[0038] The present invention also includes glass fiber reinforced articles, such as printed circuit boards, incorporating the glass fibers of the present invention. Additionally, the present invention includes products incorporating the glass fibers as disclosed above, which products can be printed circuit boards, woven fabrics, nonwoven fabrics, unidirectional fabrics, chopped strand, chopped strand mats, composite materials, and communication signal transmission media.

[0039] The present invention includes a method for providing a continuous, manufacturable, low dielectric glass fiber, which may include feeding a glass composition as disclosed herein into a melting zone of a glass melting furnace, heating the composition to a forming temperature above its liquidus temperature, and continuously spinning the molten glass to produce a low dielectric constant and low loss factor glass fiber. DETAILED DESCRIPTION OF THE INVENTION

[0040] The present invention relates to glass compositions and fibers that preferably have low dielectric constant values ​​and low loss factor (also referred to herein as tan δ). The glass fibers of the present invention are preferably suitable for applications related to electronic devices and systems that operate at high processing speeds and / or high frequencies, such as mobile or fixed wireless telephones, computers, smartphones, tablets, etc. The glass fibers of the present invention preferably yield a lower dielectric constant and loss factor than E-glass, but have better processing characteristics than D-glass. While described primarily in terms of their applications related to electronic devices and the reinforcement of printed circuit boards, other uses and advantages of the glass compositions and glass fibers of the present invention may be contemplated without departing from the spirit and scope of the present invention. The present invention also discloses glass fiber-reinforced articles, products incorporating glass fibers, such as printed circuit boards, woven fabrics, nonwoven fabrics, unidirectional fabrics, chopped strands, chopped strand mats, composites, and communication signal transmission media, as well as methods for providing continuous, producible, low dielectric glass fibers.

[0041] The compositions of the present invention are generally comprised of one or more of the following oxides, including silicon oxide (SiO), boron oxide (BO), aluminum oxide (AlO), calcium oxide (CaO), phosphorus oxide (PO), magnesium oxide (MgO), tin oxide (SnO), and titanium oxide (TiO). Additional oxides may be present as discussed below without departing from the spirit and scope of the present invention. The compositions of the present invention, in some embodiments, have a liquidus temperature greater than 1000°C and a glass viscosity of 1000 poise at temperatures (T log3) greater than 1350°C. Furthermore, the glass fibers of the present invention have a dielectric constant of 6 or less and / or a glass viscosity of 38×10 at room temperature and a frequency of 10 GHz. -4 It preferably has a loss factor of: Advantageously, the composition of the glass preferably has the ability to be continuously spun due to its positive difference between the T log3 viscosity temperature and the liquidus temperature (ΔT3).

[0042] Unless otherwise stated, the following terms used in the specification and claims have the meanings indicated below.

[0043] As used herein, the term "liquidus" generally refers to the temperature (T liq ) The term "liquidus" is given its ordinary and customary meaning, including the fact that at all temperatures above the liquidus, the glass melt is free of crystals in its primary region, and at temperatures below the liquidus, crystals are formed in the melt. The liquidus temperature therefore provides a useful lower limit temperature above which the glass can be continuously spun.

[0044] The term "spinning temperature" or "T log3 viscosity temperature" is understood to mean the temperature (denoted T log3) at which the glass has a viscosity equal to 1000 poise.

[0045] As used herein, the term "delta T," also referred to as "ΔT," is given its ordinary and customary meaning in the art, which generally includes the difference between the spinning temperature and the liquidus, and is therefore a spinnability characteristic of a glass composition. The higher the delta T, the greater the process flexibility that exists when forming glass fibers, and the less likely devitrification (crystallization) of the glass melt occurs during melting and spinning. Typically, a higher delta T results in lower glass fiber production costs, in part, by extending bushing life and providing a wider fiber-forming process window.

[0046] The term "fiber" refers to an elongated body having a length dimension greater than its transverse dimensions of width and thickness. The term fiber thus includes monofilaments, multifilaments, ribbons, strips, staples, and other forms of chopped, cut, or discontinuous fibers having regular or irregular cross-sections. Fiber and filament are used interchangeably herein.

[0047] The term "E-glass" is used in accordance with its meaning as set forth in ASTM D-578.

[0048] The term "D-glass" refers to a glass composition having the properties defined herein.

[0049] "Low dielectric constant" means glass fibers that have a lower dielectric constant than E-glass. As an example, E-glass has a dielectric constant of about 6.1 at room temperature and a frequency of 10 GHz.

[0050] "Low loss factor" means glass fiber that has a loss factor lower than that of E-glass. By way of example, E-glass has a loss factor of about 38×10 at room temperature and a frequency of about 10 GHz. -4 It has a loss factor of

[0051] "Low dielectric glass fiber" means a glass fiber having a low dielectric constant and a low loss factor as defined herein.

[0052] Generally, glass melted at a sufficiently high temperature for a sufficiently long time tends to be chemically and structurally homogeneous, i.e., free of regions of different chemical composition or atomic arrangement. Furthermore, the minimum homogeneity required for continuous spinning is a melt state in which fibers can be stably and continuously formed, with inhomogeneities too small to interfere with the spinning process. Efficient spinning requires consistent glass melt quality in terms of liquid viscosity. Viscosity fluctuations can obstruct flow and cause fiber breakage during formation. Unmelted batch material (stones), poorly melted or homogenized glass (stria / cords), and devitrification products (T liq The typical cause is defects in the glass melt due to either crystals formed at temperatures below 1000 K or 1000 K. During the course of their research, the inventors discovered that glasses in this glass family are prone to liquid-liquid immiscibility (glass phase separation) upon cooling from high temperatures. Phase separation is the tendency of a homogeneous liquid at high temperatures to thermodynamically separate into two distinct glasses upon cooling, often with significantly different compositions, liquid structures, and related properties. Furthermore, phase-separated glasses may exhibit discontinuous, rather than continuous, viscosity behavior as a function of temperature; therefore, phase-separated regions in the melt may prevent stable fiber formation.

[0053] In an attempt to understand and control this phase separation tendency, the inventors utilized the following method to characterize the stability of glass melts of each composition after melting and during cooling: After each melting cycle, the crucible was removed from the furnace and the glass transition temperature, T g The melts were allowed to cool naturally until the melt temperature was below 400°C. Less stable glasses exhibited varying degrees of opalescence (light scattering) in the cooled state. Each melt was graded ("Melt Instability Index") on a scale of 1 to 6, from no opalescence (1, very stable) to 6 (least stable, opaque). These grades were sufficient to help distinguish between areas of good glass-forming stability and areas of poor or unstable glass-forming behavior. Glasses with high Melt Instability Index values ​​(greater than 4) are expected to be difficult to spin in a continuous / stable manufacturing process. Reference to these Melt Instability Index values ​​is made throughout this specification, including with respect to the test results tables below.

[0054] Glass compositions for the formation of glass fibers are provided that are preferably suitable for use in electronic applications and articles and that can be economically formed into glass fibers, preferably by continuous spinning.

[0055] In some embodiments of the present invention, the glass fiber comprises a composition having 45 weight percent to 58 weight percent silicon dioxide (SiO2) (also referred to herein as silica). Alternatively, the silicon dioxide content may be 45.5 weight percent to 57.5 weight percent. Still alternatively, the silicon dioxide content may be 46 weight percent to 57 weight percent. In further embodiments, the silicon dioxide content may be less than 56.75 weight percent. In yet further embodiments, the silicon dioxide content may be less than 56.50 weight percent. If the silicon dioxide percentage is outside this range, the viscosity and spinning of the glass are typically affected. For example, if the silicon dioxide is less than 45 weight percent of the total composition of the glass fiber, the viscosity of the glass may decrease to the point where devitrification (crystallization) occurs during spinning. In contrast, if the silicon dioxide is more than 58 weight percent of the total composition of the glass fiber, the glass may become too viscous, making melting, homogenization, and refining more difficult. For this reason, the silica content is preferably between 45 and 58 weight percent of the total glass composition. Furthermore, when combined with other components as defined herein, a silica content between 45.00 and 58.00 weight percent typically results in glass fibers with a desirable low dielectric constant as well as a low loss factor. In one embodiment of the glass fibers and / or glass compositions of the present invention, the silica content is at least 45.50 weight percent. Alternatively, the silica content is at least 46.00 weight percent. In another embodiment of the glass fibers and / or glass compositions of the present invention, the silica content is 57.50 weight percent or less. Alternatively, the silica content is 57.00 weight percent or less. Still alternatively, the silica content is 56.75 weight percent or less. In another embodiment, the silica content is 56.50 weight percent or less.

[0056] Notwithstanding the above, the present inventors have identified certain surprisingly useful and / or effective formulations comprising compositions in which the glass fibers have 48 weight percent to 58 weight percent silicon dioxide (SiO2). Alternatively, the silicon dioxide content may be 49 weight percent to 57.5 weight percent. Still alternatively, the silicon dioxide content may be 50 weight percent to 57 weight percent. In further embodiments, the silicon dioxide content may be less than 57.0 weight percent. If the silicon dioxide percentage is outside these ranges, the viscosity and spinning of the glass are typically affected. For example, if the silicon dioxide is less than 48 weight percent of the total composition of the glass fibers, the viscosity of the glass may decrease to the point where devitrification (crystallization) occurs during spinning. In contrast, if the silicon dioxide is more than 58 weight percent of the total composition of the glass fibers, the viscosity of the glass may become too high, making melting, homogenization, and refining more difficult. Therefore, the silica content is preferably 48 to 58 weight percent of the total composition of the glass. Also, SiO2 is useful for controlling the stability of the compound, and the weight percent of SiO2 is also It should be understood that the selection is arbitrary based on such considerations in combination with other factors described herein.

[0057] In some embodiments of the present invention, the glass fibers comprise compositions having greater than 18 weight percent boron oxide (BO) and less than or equal to 26 weight percent boron oxide. Alternatively, the boron oxide content may be between 18.5 weight percent and 25 weight percent. Further alternatively, the boron oxide content may be between 19 weight percent and 22 weight percent. High percentages of boron oxide, such as greater than 26 weight percent, can cause excessive loss of BO upon melting, poor homogeneity, low strength, and poor mechanical properties. When combined with other components defined herein, a boron oxide content greater than 18.00 weight percent and less than or equal to 26.00 weight percent typically results in glass fibers having a desirable low dielectric constant as well as a low loss factor. In one embodiment of the glass fibers and / or glass compositions of the present invention, the boron oxide content is at least 18.50 weight percent. Alternatively, the boron oxide content is at least 19.00 weight percent. In another embodiment of the glass fibers and / or glass compositions of the present invention, the boron oxide content is less than or equal to 25.00 weight percent. Alternatively, the boron oxide content is less than or equal to 24.00 weight percent.

[0058] Notwithstanding the above, the present inventors have identified certain surprisingly useful and / or effective formulations comprising compositions in which glass fibers have between 15 weight percent boron oxide (BO) and 26 weight percent boron oxide. While BO is beneficial for lowering Df, it is generally understood that too much BO can cause glass instability in the form of phase separation. Alternatively, the boron oxide content may be between 15.5 weight percent and 25.5 weight percent. Further alternatively, the boron oxide content may be between 16 weight percent and 25 weight percent. Higher percentages of boron oxide, such as greater than 26 weight percent, can cause excessive loss of BO upon melting, poor homogeneity, poor mechanical properties, and glass instability in the form of phase separation. Furthermore, lower percentages of boron oxide, such as less than 15 weight percent, can cause poor dielectric properties. For this reason, the boron oxide content is preferably between 15 weight percent and 26 weight percent of the total glass composition. Furthermore, when combined with other components as defined herein, a boron oxide content of 15.00 weight percent to 26.00 weight percent typically results in glass fibers having a desirably low dielectric constant as well as a low loss factor. In one embodiment of the glass fibers and / or glass compositions of the present invention, the boron oxide content is at least 16.0 weight percent. Further, alternatively and / or optionally, the boron oxide content is 20.00 weight percent or less. In another embodiment of the glass fibers and / or glass compositions of the present invention, the boron oxide content is 25.00 weight percent or less.

[0059] In some embodiments of the present invention, the glass fiber comprises a composition having greater than 16 weight percent and less than or equal to 23 weight percent aluminum oxide. Alternatively, the aluminum oxide content may be greater than 16 weight percent and less than or equal to 22.5 weight percent. Further alternatively, the aluminum oxide content may be greater than 16 weight percent and less than or equal to 22 weight percent. The percentage of aluminum oxide relative to the total composition of the glass fiber can also affect viscosity and the spinning process. For example, a high percentage of aluminum oxide, such as greater than 23 weight percent, can reduce the melt viscosity and cause devitrification during spinning. A low percentage of aluminum oxide, such as less than or equal to 18 weight percent, can cause phase separation and poor fiber formation. For this reason, the alumina content is preferably greater than 16 weight percent and less than or equal to 23 weight percent of the total glass composition. Furthermore, when combined with other components as defined herein, an alumina content of 16.00 weight percent to 23.00 weight percent typically provides a desirable low dielectric constant. This not only results in glass fibers with a low loss factor, but also in glass fibers with a low loss factor. In one embodiment of the glass fibers and / or glass compositions of the present invention, the alumina content is 22.50 weight percent or less. Alternatively, the alumina content is 22.00 weight percent or less.

[0060] Aluminum oxide is known to stabilize glasses prone to phase separation / melting instability. However, at high levels, it is also known to increase the tendency for devitrification / crystallization, and thus may adversely affect fiber formation stability with respect to Delta T. Considering these tendencies of Al2O3, which is in some respects the opposite of B2O3, for example, and the other components of the described formulation, it is important to find the correct balance between them all. In light of the above, and notwithstanding the ranges previously disclosed herein, the inventors have found that in some embodiments of the present invention, Al2O3 present in the range of 12 weight percent to 18 weight percent provides excellent Df behavior and T. liqWe have identified certain surprisingly useful and / or effective formulations in which a balance of performance is achieved. In some embodiments of the invention, Al2O3 is present in a range of 12.5 weight percent to 17.5 weight percent. In some embodiments of the invention, Al2O3 is present in a range of 13 weight percent to 17 weight percent. It should be understood that these ranges are provided to aid the reader in envisioning a working formulation of our compositions, and it should also be understood that formulations using any weight percent of Al2O3, including those within any of the ranges described herein, can be used to achieve a formulation acceptable for the stated purposes of the invention.

[0061] The glass fibers of the present invention also typically include compositions having greater than 0.25 weight percent to 3 weight percent phosphorus oxide (P2O5, also known as phosphorus pentoxide). The inventors have surprisingly found that this range significantly improves Df behavior and T liq and melt instability index. More specifically, P2O5 interacts synergistically with the Al2O3 content of the glass, decreasing the melt stability (increasing the instability index value) while simultaneously increasing Df and T liq It has also been found to improve the critical numerical indicators of porosity (P / P). The inventors speculate that phosphorus selectively associates with a portion of Al2O3, forming AlPO4 network links that prevent some of the Al2O3 from devitrifying to the aluminoborate mullite. It should also be noted that the inventors have determined that this range of greater than 0.25 weight percent to 3 weight percent P2O5, when combined with the specified ranges of other compositional components as described herein, improves the manufacturability of low dielectric loss glasses. That is, phosphorus is intentionally selected for use in many of the compositions described herein, despite the fact that it is known to those skilled in the art to adversely affect some desirable properties of the resulting glass, such as increased glass viscosity. However, by carefully balancing the other elements in the composition, combined with the inventors' discoveries regarding the surprising behavior of certain combinations of these elements, successful glass compositions can be achieved.

[0062] Alkaline earth oxides (magnesium oxide (MgO) and / or calcium oxide (CaO)) help these glasses melt and homogenize at reasonable temperatures achievable by melting furnaces known in the art. However, these oxides directly impact and impair the low dielectric behavior desired by the industry (MgO does not increase Df more than CaO). CaO typically exhibits lower viscosity, T liq and Df. Also, too little alkaline earth oxide leads to an unstable glass melt (high index). For at least this reason, the glass fiber composition of the present invention may also contain CaO (also referred to herein as calcia) and / or MgO, as described below.

[0063] The glass fibers of the present invention, in some embodiments of the present invention, comprise a composition having greater than 0.25 weight percent calcium oxide to 7.0 weight percent calcium oxide. Alternatively, the calcium oxide content may be greater than 0.25 weight percent to 6.5 weight percent. Further alternatively, the calcium oxide content may be greater than 0.25 weight percent to 6 weight percent. Still further alternatively, the calcium oxide content may be greater than 2.5 weight percent to 5.0 weight percent. The weight percent of calcium oxide can affect the viscosity of the glass fiber and the devitrification process. A high percentage of calcium oxide, such as greater than 7.0 weight percent, can cause poor dielectric properties. Furthermore, a low percentage of calcium oxide, such as 0.25 weight percent or less, can cause poor fiber formation. For example, with calcia less than 0.25 weight percent, the viscosity is too high and the resulting glass homogeneity is insufficient for acceptable continuous fiber formation. When combined with other components defined herein, in some embodiments, a calcium oxide content of 1.0 weight percent to 6.0 weight percent typically results in glass fibers having not only a desirable low dielectric constant but also a low loss factor. In one embodiment of the glass fiber and / or glass composition of the present invention, the calcia content is 4.5 weight percent or less. Alternatively, the calcia content is 4.25 weight percent or less. Still alternatively, the calcia content is 4.00 weight percent or less.

[0064] The glass fiber compositions of the present invention may also include MgO (also referred to herein as magnesia). The glass fibers of the present invention may include compositions having 5.0 weight percent or less of magnesium oxide. Alternatively, the magnesium oxide content may be 4.5 weight percent or less. Still alternatively, the magnesium oxide content may be 4.0 weight percent or less. In a further alternative embodiment, the magnesium oxide content may be 2.0 weight percent or less. In a further alternative embodiment, the magnesium oxide content may be 1.5 weight percent or less. Similar to calcium oxide, the weight percent of magnesium oxide also affects the viscosity and devitrification process of the glass fiber. Furthermore, high percentages of magnesium oxide, such as above 5.0 weight percent, may cause poor dielectric properties.

[0065] The inventors have discovered that, in preferred embodiments of the present invention, certain glass compositions require the presence of tin oxide (SnO) to provide the desired performance characteristics for this type of glass while still being reasonably, commercially, and / or effectively manufacturable. It should be noted that the addition of this element runs counter to conventional wisdom among those skilled in the art, as large cationic species are known in the art to adversely affect high-frequency dielectric loss behavior in glasses (exactly the type of glasses the inventors are making herein). One example of a large cationic species that adversely affects high-frequency dielectric loss behavior in glasses is calcium oxide, which is included in these types of glasses in limited amounts to the limit because its desirable positive effects on the glass composition outweigh its negative effects. Tin oxide is intentionally added to the glass formulations described herein and has three times the atomic weight of calcium oxide. While it is generally understood by those skilled in the art that the addition of tin oxide will have adverse effects on this type of glass (i.e., significantly worse than calcium oxide due to the size difference), the inventors have surprisingly discovered that SnO does not adversely affect the Df behavior of these glasses up to 1.5 weight percent. Thus, in one embodiment of the present invention, tin oxide is used in the present glass compositions as a fining agent to remove seeds and hollow filaments, improving their quality and performance, but without significantly affecting the desired low dielectric loss glass property, contrary to the commonly held belief that tin oxide impairs this particular property.

[0066] Titanium oxide (TiO) is optionally present or intentionally introduced into the glass compositions and fibers of the present invention. In one embodiment, the weight percent of titanium oxide is 6.0 or less. Alternatively, the weight percent of titanium oxide is 5.5 or less. Still alternatively, , the weight percent of titanium oxide is 5.0 or less. Titanium oxide greater than 6 weight percent appears to increase the tendency for phase separation in the glass composition and fibers, especially when combined with phosphorus pentoxide. Titanium oxide typically acts as a viscosity reducer and may be intentionally added or present as an impurity from conventional raw materials. Thus, titanium oxide may be present in the glass composition at 0.01 weight percent or greater. Alternatively, titanium oxide may be present in the glass composition at 0.05 weight percent or greater. Still alternatively, titanium oxide may be present in the glass composition at 0.1 weight percent or greater. In some embodiments, titanium dioxide is present in the glass composition at less than 0.5 weight percent.

[0067] Since the stated objective of this invention is to produce the most stable glass reasonably possible for the melting and spinning process, it is believed that up to 6 weight percent TiO2 in this family is sufficient to produce a glass that is stable to the melting and spinning process. liq It would also not have been expected by one skilled in the art that the glass could be tolerated without adversely affecting the properties of the glass and without producing delta T behavior (delta T<40°C) that would make these glasses unspinnable. Wolfram Holland, et al., Glass Ceramic Technology, 2nd Edition, See Wiley and Sons, July 2012, p. 37.

[0068] TiO2 is used in combination with other low D k In light of this, the inventors have determined that any amount of nucleating agent (TiO, crystallization rate and optionally T liq Although expected to increase viscosity (T log3), it is also known to decrease viscosity (T log3) by incorporating liq ) was something that defied common sense.

[0069] Interestingly, none of the relevant prior art provides any examples of combining P2O5 with significant amounts of SnO2 and TiO2, making it difficult to predict any synergistic or desirable behavior.

[0070] Additional oxides may be present in the glass fibers and compositions of the present invention without departing from the scope of the present invention. For example, oxides such as lithium oxide (LiO), sodium oxide (NaO), potassium oxide (KO), barium oxide (BaO), strontium oxide (SrO), zinc oxide (ZnO), fluorine (F or F), zirconium oxide (ZrO), chromium oxide (CrO), iron oxide (FeO), lanthanum oxide (LaO), manganese oxide (MnO), yttrium oxide (YO), and / or vanadium oxide (VO) may be present. Furthermore, the total amount of these additional oxides is limited to 3 weight percent or less of the total composition, provided that the total amount does not alter the functionality of the glass. Alternatively, the total amount of these additional oxides may be limited to 2 weight percent or less of the total composition. Further alternatively, the total amount of these additional oxides may be limited to 1.5 weight percent or less of the total composition. Further alternatively, the sum of these additional oxides may be less than or equal to 3.0 weight percent, 2.0 weight percent, and / or 1.0 weight percent of the total composition in some embodiments of the present invention.

[0071] Because even trace amounts of alkali metal oxides can have a significant effect on the glass composition, the total amount of alkali metal oxides, such as NaO, KO, and LiO, is preferably 1.0 weight percent or less of the total composition, more preferably 0.5 weight percent or less of the total composition, and even more preferably 0.25 weight percent or less of the total composition.

[0072] Examples of glass compositions and glass fibers of the present invention are described herein. In one embodiment, the glass composition and / or glass fibers comprise 48.0 weight percent to 58.0 weight percent. percent SiO2, 15.0 weight percent to 26.0 weight percent B2O3, 12.0 weight percent to 18.0 weight percent Al2O3, greater than 0.25 weight percent to 3.0 weight percent P2O5, greater than 0.25 weight percent to 7.0 weight percent CaO, 5.0 weight percent or less MgO, greater than 0 weight percent to 1.5 weight percent SnO2, and 6.0 weight percent or less TiO2. Alternative glass compositions and / or glass fibers of the present invention can include 49 weight percent to 57.5 weight percent SiO2, 15.5 weight percent to 25.5 weight percent B2O3, 12.5 weight percent to 17.5 weight percent Al2O3, greater than 0.25 weight percent to 3.0 weight percent P2O5, greater than 0.25 weight percent to 6.5 weight percent CaO, 4.50 weight percent or less MgO, greater than 0 weight percent to 1.25 weight percent SnO2, and 5.5 weight percent or less TiO2. Further alternative glass compositions and / or glass fibers of the present invention may include the following components: 50 weight percent to 57.0 weight percent SiO2, 16.0 weight percent to 25.0 weight percent B2O3, 13.0 weight percent to 17.0 weight percent Al2O3, greater than 0.25 weight percent to 3.0 weight percent P2O5, greater than 0.25 weight percent to 6.0 weight percent CaO, 4.0 weight percent or less MgO, greater than 0 weight percent to 1.00 weight percent SnO2, and 5.0 weight percent or less TiO2.

[0073] The glass composition of the present invention has a liquidus temperature above 1000° C. In an alternative embodiment, the glass composition may have a liquidus temperature above 1050° C. In a further alternative embodiment, the glass composition may have a liquidus temperature above 1100° C. A liquidus temperature above 1000° C., or more preferably above 1050° C., is advantageous for spinning the glass composition according to the present invention.

[0074] Additionally, the glass composition of the present invention may have a T log3 viscosity temperature greater than 1350° C. Alternatively, the glass composition may have a T log3 viscosity temperature greater than 1355° C. In a further alternative embodiment, the glass composition may have a T log3 viscosity temperature greater than 1360° C. A T log3 viscosity temperature greater than 1350° C. is advantageous for spinning the glass composition according to the present invention.

[0075] The glass fibers of the present invention may have a dielectric constant of less than or equal to 6. Alternatively, the glass fibers may have a dielectric constant of less than or equal to 4.80. In a further alternative embodiment, the glass fibers may have a dielectric constant of less than or equal to 4.70.

[0076] Furthermore, the glass fiber of the present invention has a fiber optics characteristic of 38×10 at a frequency of 10 GHz at room temperature. -4 Alternatively, the glass fiber may have a loss factor of 30×10 at room temperature and a frequency of 10 GHz. -4 In a further alternative embodiment, the glass fibers of the present invention may have a loss factor of 28×10 at a frequency of 10 GHz at room temperature. -4 It may have the following loss factors:

[0077] The glass fibers of the present invention can be incorporated into glass fiber reinforced articles such as printed circuit boards, etc. Additionally, the glass fibers of the present invention can be used in connection with products such as woven fabrics, nonwoven fabrics, unidirectional fabrics, chopped strands, chopped strand mats, composite materials, and communication signal transmission media.

[0078] The present invention also includes a method for providing a continuous, manufacturable, low dielectric glass fiber, which may include feeding a glass composition as disclosed herein into a melting zone of a glass melting furnace, heating the composition to a forming temperature above its liquidus temperature, and continuously spinning the molten glass to produce a low dielectric constant and low loss factor glass fiber.

[0079] As discussed above, the composition of the glass to provide the low dielectric constant glass fiber is based, at least in part, on the weight percent of the oxides discussed above, as well as the ratio and total weight of silicon dioxide, aluminum oxide, boron oxide, calcium oxide, magnesium oxide, phosphorus oxide, tin oxide, and / or titanium oxide. In one aspect, the combination of these parameters, in addition to other parameters discussed herein, such as T log3 viscosity temperature, can result in glass fibers having the low dielectric constant and low loss factor defined herein.

[0080] In comparison to previous attempts in the field, Creux's formulation is shown in two examples in U.S. Pat. No. 5,629,493. As shown in Figure 1, this glass exhibits completely poor Df behavior (Df ≈ 0.0090 at 10 GHz). In contrast, the present invention achieves Df < 0.0028. Furthermore, Creux's T log3 is below 1350°C, T liq is less than 1000°C.

[0081] On the other hand, Zhang does not describe the Df behavior of his glasses at all. The T log3 of Zhang's glasses is less than 1350°C, and T liq All are below 1000°C. Interestingly, Zhang found that the primary crystals (wollastonite / diopside / calcium feldspar) are all in contact with each other. The glass is described as having excellent devitrification behavior due to its competitiveness. See paragraph

[0014] of Patent Document 8.

[0082] Current state-of-the-art glass families have a T below 1000°C liq and T log3 viscosity temperature of less than 1350°C, it is clear that most, if not all, of the above prior art techniques have not been combined to achieve the glass inventions now described.

[0083] It is known in the art that chemical composition largely determines the primary crystals that devitrify from a glass melt. See Holand at page 4.

[0084] It is known in the art that TiO2 is used by glass manufacturers as a nucleating agent to promote crystallization and aid in devitrification of glass. See Holand at page 37. However, none of the prior art, including Mori U.S. Pat. No. 5,629,999, Tamura U.S. Pat. No. 5,629,999, Tamura U.S. Pat. No. 5,629,999, and Yoshida U.S. Pat. No. 5,629,999, discloses TiO2 incorporated in the amounts described herein by the inventors. There is no evidence or demonstration of the effective use of TiO2 with significant and / or significant amounts of P2O5 and SnO2 which, when combined, are believed to produce unexpected effects.

[0085] Furthermore, the inventors have unexpectedly discovered that the measured dielectric loss of the present glasses appears to be closely related to the crystallization behavior of the present glasses. liq Glasses with higher Df values ​​tend to have better, i.e., lower, Df properties.

[0086] To achieve the desired Df behavior (Df<0.0028 or <0.0027 or <0.0026 or even lower), glasses defined by the formulations disclosed herein by the inventors are more easily processed, i.e., at higher T liq It is clear that devitrification tends to occur at values ​​of Df, for example, above 1000°C. Furthermore, the most desirable Df value is a T value significantly higher than 1000°C. liq is located.

[0087] The inventors have further surprisingly discovered that the most desirable glasses for obtaining low Df behavior are those that have an inherent network structure that favors crystallization into and formation of aluminoborate mullite (needle-like) crystals as the primary devitrified phase.

[0088] On the other hand, Zhang reported that the glass contained wollastonite, diopside, and Ca-feldspar crystals. It is stated that it produces mullite and not aluminoborate mullite.

[0089] The inventors speculate that glasses that tend to fall within this aluminoborate mullite primary region have an inherently favorable network structure for both good glass formation and excellent (i.e., low) Df behavior.

[0090] Like Creux, the glass invented by Kuhn (Patent Document 5) also exhibits poor Df behavior (D f≧0.0044), and only Example 1 of the six examples shows a positive Delta T for acceptable fibrillation (see Table II of Kuhn).

[0091] Having generally described herein the inventors' discoveries and unexpectedly effective formulations, a further understanding can be obtained by reference to certain specific examples illustrated below, which are presented for purposes of illustration only and are not intended to be exhaustive or limiting unless otherwise specified. [Example]

[0092] Examples of glass compositions made in accordance with the present invention are set forth below. The specific components and amounts thereof recited in these examples, as well as other conditions and details, should not be construed as unduly limiting the present invention. In these examples, and throughout this specification, all percentages, proportions, and ratios are by weight (mass) unless otherwise indicated.

[0093] Exemplary glass compositions of the present invention are shown in Tables 1 to 12 below. The liquidus temperatures of the glass compositions of the examples are shown as "T liq」 The liquidus temperature and T3 temperature of the example glass compositions are expressed as "Dk" values, and the temperature at which the glass composition had a viscosity of 1000 poise is expressed as "T3" (also referred to as the "T log3" viscosity temperature). The liquidus temperature and T3 temperature of the example glass compositions were measured for some glass compositions and calculated for others. The example compositions were used to form glass fibers, and the dielectric constant and loss factor were measured for some glass fibers and calculated for others. The dielectric constant is expressed as a "Dk" value, and the loss factor is expressed as a "Df" value.

[0094] Table 1

[0095] Table 2

[0096] Table 3

[0097] Table 4

[0098] Table 5

[0099] Table 6

[0100] Table 7

[0101] Table 8

[0102] Table 9

[0103] Table 10

[0104] Table 11

[0105] [Table 12]

[0106] Batches having the sample glass compositions shown in Tables 1-12 are typically prepared as follows: Glass synthesis typically involves batch preparation (mechanical and thermal), first melting, fritting or grinding in water, second melting, and finally pouring the glass into graphite molds.

[0107] Glass samples were typically tested for crystallization potential (liquidus temperature) according to ASTM C 829-81.

[0108] T log3 viscosity temperature was typically measured using ASTM C 965-81.

[0109] Measurement of dielectric properties at 10 GHz is typically performed using the Split Post Dielectric Resonator method, also referred to in the art as SPDR testing. cormorant.

[0110] As shown in Tables 1 to 12, at 10 GHz, the glass compositions of the examples had a dielectric constant of 4.75 or less and a dielectric constant of 28×10 -4 Specifically, at 10 GHz, the dielectric constant is 4.34 to 4.75, and the loss factor is 19 × 10 -4 ~28×10 -4 Therefore, the glass compositions of the examples exhibited low dielectric constants and loss factors that were lower than the dielectric properties of E-glass.

[0111] Furthermore, the glass compositions of the examples exhibited T log3 viscosity temperatures of 1352°C to 1431°C, which are similar to the typical T log3 viscosity temperature of D-glass (approximately 1400°C). Having a T log3 viscosity temperature above 1350°C is advantageous for spinning glass compositions according to the present invention. Thus, the glass compositions of the examples and embodiments of the present invention exceed 1350°C.

[0112] Furthermore, the glass compositions of the examples exhibited liquidus temperatures between 1011° C. and 1342° C. Having a liquidus temperature above 1000° C., or in some embodiments above 1050° C., is sufficient for spinning of glass compositions according to the invention. Thus, the glass compositions according to the examples and embodiments of the invention exceed 1000° C. [Industrial Applicability]

[0113] The glass fiber of the present invention has a low dielectric constant and a low loss factor, making it an excellent glass fiber for printed wiring boards. The glass fiber is particularly suitable for reinforcing printed wiring boards for high-density circuits used in high-speed routing systems. Furthermore, the glass composition used to prepare the fiber of the present invention has excellent processability. Therefore, stable low-dielectric glass fibers can be easily produced.

[0114] A variety of substrates can be manufactured containing the glass fibers of the present invention, including, but not limited to, woven fabrics, nonwoven fabrics, unidirectional fabrics, knitted products, chopped strands, rovings, filament wound products, glass powders, and mats. Composite materials formed from at least one of these substrates and a plastic resin matrix (such as a thermoset plastic, a composite thermoplastic, a sheet molding compound, a bulk molding compound, or a prepreg) can also be used to reinforce peripheral communication devices and the like. For example, composite materials containing glass fibers according to the present invention can be used in radar-penetrating applications at frequencies ranging from about 300 MHz to about 30 GHz.

[0115] The disclosed and described method relates to glass fibers, which can be obtained by mechanically attenuating a stream of molten glass emerging from an opening located at the base of a spinning bushing powered by resistive heating or other means. These glass fibers are made of organic and and / or may be specifically directed to the production of meshes and fabrics for use in composite materials with an inorganic matrix.

[0116] Where necessary, detailed embodiments of the present invention are disclosed herein. However, it should be understood that the disclosed embodiments are merely exemplary of the present invention, which may be embodied in various alternative forms. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a basis for the claims and as a representative basis for teaching those skilled in the art how to use the present invention in various ways. It will be apparent to those skilled in the art that many modifications and substitutions can be made to the above description of preferred embodiments and examples without departing from the spirit and scope of the present invention, as defined by the appended claims.

[0117] While various embodiments and examples of the present invention have been described above, these descriptions are presented for purposes of illustration and description. Variations, changes, modifications and departures from the above-disclosed embodiments, systems and methods may be employed without departing from the spirit and scope of the invention.

Claims

1. 1. A glass composition comprising: 48.0 weight percent to 58.0 weight percent SiO ２ Including, 15.0 weight percent to 26.0 weight percent B ２ O ３ Including, 12.0 weight percent to 18.0 weight percent Al ２ O ３ Including, greater than 0.25 weight percent to 3.0 weight percent P ２ O ５ Including, greater than 0.25 weight percent to 7.0 weight percent CaO; Contains no more than 5.0 weight percent MgO; greater than 0 weight percent to 1.5 weight percent SnO ２ and consisting essentially of: 6.0 weight percent or less TiO ２ Including, A glass composition having a glass viscosity of 1000 poise at temperatures above 1350°C and a liquidus temperature above 1000°C.

2. 49.0 weight percent to 57.5 weight percent SiO ２ Further comprising: 15.5 weight percent to 25.5 weight percent B ２ O ３ Further comprising: 12.5 weight percent to 17.50 weight percent Al ２ O ３ Further comprising: greater than 0.25 weight percent to 3.0 weight percent P ２ O ５ Further comprising: further comprising greater than 0.25 weight percent to 6.5 weight percent CaO; further comprising up to 4.5 weight percent MgO; greater than 0 weight percent to 1.25 weight percent SnO ２ and consisting essentially of: 5.5 weight percent or less TiO ２ Further comprising: The glass composition of claim 1 .

3. 50.0 weight percent to 57.0 weight percent SiO ２ Further comprising: 16.0 weight percent to 25.0 weight percent B ２ O ３ Further comprising: 13.0 weight percent to 17.0 weight percent Al ２ O ３ Further comprising: greater than 0.25 weight percent to 3.0 weight percent P ２ O ５ Further comprising: further comprising greater than 0.25 weight percent to 6.0 weight percent CaO; further comprising up to 4.0 weight percent MgO; greater than 0 weight percent to 1.0 weight percent SnO ２ and consisting essentially of: 5.0 weight percent or less TiO ２ Further comprising: The glass composition of claim 1 .

4. 49.0 weight percent or more of SiO ２ , 57.5 weight percent or less of SiO ２ , 15.5 weight percent or more of B ２ O ３ , 25.5 weight percent or less of B ２ O ３ , 12.50 weight percent or more of Al ２ O ３ , 17.50 weight percent or less Al ２ O ３ , greater than 0.25 weight percent P ２ O ５ , 3.0 weight percent or less P ２ O ５ , greater than 0.25 weight percent CaO, not more than 6.5 weight percent CaO; up to 4.5 weight percent MgO; greater than 0 weight percent SnO ２ , 1.25 weight percent or less SnO ２ and / or 5.5 weight percent or less TiO ２ , The glass composition of claim 1 further comprising one or more of:

5. 50.0 weight percent or more of SiO ２ , 57.0 weight percent or less of SiO ２ , 16.0 weight percent or more of B ２ O ３ , 25.0 weight percent or less of B ２ O ３ , 13.0 weight percent or more of Al ２ O ３ , 17.0 weight percent or less Al ２ O ３ , greater than 0.25 weight percent P ２ O ５ , 3.0 weight percent or less P ２ O ５ , greater than 0.25 weight percent CaO, 6.0 weight percent or less of CaO; up to 4.0 weight percent MgO; greater than 0 weight percent SnO ２ , 1.0 weight percent or less SnO ２ and / or 5.0 weight percent or less TiO ２ , The glass composition of claim 1 further comprising one or more of:

6. 2. The glass composition of claim 1, which has an inherent network structure that crystallizes into and tends to form aluminoborate mullite crystals as the first devitrified phase.

7. supplying the glass composition of claim 1 to a melting zone of a glass melting furnace; heating the composition to a molding temperature above the liquidus temperature; continuously spinning the molten glass to produce glass fibers having a low dielectric constant and a low loss factor; 1. A method for providing a continuous, manufacturable, low dielectric glass fiber, comprising:

8. 48.0 weight percent to 58.0 weight percent SiO ２ Including, 15.0 weight percent to 26.0 weight percent B ２ O ３ Including, 12.0 weight percent to 18.0 weight percent Al ２ O ３ Including, greater than 0.25 weight percent to 3.0 weight percent P ２ O ５ Including, greater than 0.25 weight percent to 7.00 weight percent CaO; Contains no more than 5.0 weight percent MgO; greater than 0 weight percent to 1.5 weight percent SnO ２ and consisting essentially of: 6.0 weight percent or less TiO ２ Including, A low dielectric glass fiber formed from a glass composition having a glass viscosity of 1000 poise at temperatures above 1350°C and a liquidus temperature above 1000°C.

9. The glass composition comprises: 49.0 weight percent to 57.5 weight percent SiO ２ Further comprising: 15.5 weight percent to 25.5 weight percent B ２ O ３ Further comprising: 12.5 weight percent to 17.50 weight percent Al ２ O ３ Further comprising: greater than 0.25 weight percent to 3.0 weight percent P ２ O ５ Further comprising: further comprising greater than 0.25 weight percent to 6.5 weight percent CaO; further comprising up to 4.5 weight percent MgO; greater than 0 weight percent to 1.25 weight percent SnO ２ and consisting essentially of: 5.5 weight percent or less TiO ２ Further comprising: The low dielectric glass fiber according to claim 8.

10. The glass composition comprises: 50.0 weight percent to 57.0 weight percent SiO ２ Further comprising: 16.0 weight percent to 25.0 weight percent B ２ O ３ Further comprising: 13.0 weight percent to 17.0 weight percent Al ２ O ３ Further comprising: greater than 0.25 weight percent to 3.0 weight percent P ２ O ５ Further comprising: further comprising greater than 0.25 weight percent to 6.0 weight percent CaO; further comprising 4.0 percent by weight or less MgO; greater than 0 weight percent to 1.0 weight percent SnO ２ and consisting essentially of: 5.0 weight percent or less TiO ２ Further comprising: The low dielectric glass fiber according to claim 8.

11. The glass composition comprises: 49.0 weight percent or more of SiO ２ , 57.5 weight percent or less of SiO ２ , 15.5 weight percent or more of B ２ O ３ , 25.5 weight percent or less of B ２ O ３ , 12.5 weight percent or more of Al ２ O ３ , 17.50 weight percent or less Al ２ O ３ , greater than 0.25 weight percent P ２ O ５ , 3.0 weight percent or less P ２ O ５ , greater than 0.25 weight percent CaO, not more than 6.5 weight percent CaO; up to 4.5 weight percent MgO; greater than 0 weight percent SnO ２ , 1.25 weight percent or less SnO ２ and / or 5.5 weight percent or less TiO ２ , The low dielectric glass fiber according to claim 8, further comprising one or more of:

12. The glass composition comprises: 50.0 weight percent or more of SiO ２ , 57.0 weight percent or less of SiO ２ , 16.0 weight percent or more of B ２ O ３ , 25.0 weight percent or less of B ２ O ３ , 13.0 weight percent or more of Al ２ O ３ , 17.0 weight percent or less Al ２ O ３ , greater than 0.25 weight percent P ２ O ５ , 3.0 weight percent or less P ２ O ５ , greater than 0.25 weight percent CaO, 6.0 weight percent or less of CaO; up to 4.0 weight percent MgO; greater than 0 weight percent SnO ２ , 1.0 weight percent or less SnO ２ and / or 5.0 weight percent or less TiO ２ , The low dielectric glass fiber according to claim 8, further comprising one or more of:

13. A dielectric constant of 6 or less and / or 38 x 10 at a frequency of 10 GHz at room temperature －４ 9. The glass fiber of claim 8, having a loss factor of:

14. A dielectric constant of 4.80 or less at a frequency of 10 GHz at room temperature and / or a dielectric constant of 30 x 10 －４ 9. The glass fiber of claim 8, having a loss factor of:

15. A dielectric constant of 4.70 or less at a frequency of 10 GHz at room temperature and / or a dielectric constant of 28 x 10 －４ 9. The glass fiber of claim 8, having a loss factor of:

16. A glass fiber reinforced article comprising the glass fiber of claim 8.

17. 17. The glass fiber reinforced article of claim 16 which is a printed circuit board.

18. 9. The glass fiber of claim 8, formed from a glass composition that crystallizes into and has an inherent network structure that favors the formation of aluminoborate mullite crystals.

19. 10. An article comprising the glass fibers of claim 8, selected from the group consisting of printed circuit boards, woven fabrics, nonwoven fabrics, unidirectional fabrics, chopped strands, chopped strand mats, composite materials, and communication signal transport media.

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