Glass components and glass fibers and their manufacturing methods

Abstract

This invention provides a glass composition, expressed as a percentage by mass, containing the following components: 45≦SiO₂≦80, 10≦B₂O₃≦40, 0.1≦Al₂O₃≦20, 0.1≦(MgO+CaO)≦10, 0≦(Li₂O+Na₂O+K₂O)≦5, 0.1≦T-SnO₂≦2 (where T-SnO₂ is converted to tin oxide of SnO₂); and based on mass, 0≦MgO / (MgO+CaO)≦0.50 holds true. This glass composition is suitable for stably manufacturing glass fibers with low dielectric constants.

Description

Technical field

[0001] The present invention relates to a method of manufacturing a glass composition, a glass fiber composed of the composition, and a glass fiber. Prior technology

[0002] Resin compositions are widely used as electrically insulating members and mechanism members in various parts equipped with electronic machines. Examples of electrically insulated members are: connector shells for SMT (surface mount technology), FPC (flexible printed circuits, soft printed circuits), board (board), CPU (central processing unit) slots, memory cards, card edges, optical connectors, etc.; display) bobbin for reactances for backlights, coils, flat panels, transformers, magnetic heads, etc.;switchers for relay housings, relay base switches, reflow DIP switches, touch switches, etc.; Examples of mechanism parts are: lens frames and pickup bases for optical pickups, insulators and terminals for micro electric motors, and drums for laser printers. The resin composition is also used as a base film for FPC and a base film for copper-clad laminates. Furthermore, one type of printed circuit board equipped with an electronic machine also has a substrate composed of a resin composition. The printed wiring board before installing the electronic component also has a substrate constructed of a resin composition. Below, in this instruction, both the printed circuit board and the printed patch panel are combined as "printed board".

[0003] The above resin compositions comprise thermoplastic resins and glass fibers, which, as necessary, include hardeners, modifiers, and the like. Inorganic filler materials are sometimes further included in the printed substrate. As an inorganic filling material, glass fillers are sometimes used. In recent years, in response to the demand for miniaturization of electronic machines, and for thinning for high functionalization purposes, lower dielectric constants of resin compositions are required and correspondingly lower dielectric constants of their constituent materials. A glass fiber composed of a glass composition of low dielectric constant is revealed in patent literature 1 . [Previous technical literature] [Patent Literature]

[0004] Patent Literature 1: Bulletin No. 62-226839 of Tekaisho, Japan Contents of the invention

[0005] [Problems to be solved by the invention]

[0006] For glass compositions, they are required to have suitable characteristics for mass production. For example, fiberglass fibers are obtained by spinning a glass blank that has been fused in a refractory furnace slot. In the fabrication method of such glass fibers, breakage of the glass fibers is prone to occur due to air bubbles present in the glass blank. In particular, the viscosity of glass compositions with low dielectric constants is relatively high, and the air bubbles generated during the melting of glass raw materials are easily retained in the glass blank. There are improvements in the technique of fabricating glass fibers composed of glass compositions of low dielectric constant.

[0007] One object of the present invention is to provide a glass composition capable of stably fabricating as a glass fiber of low dielectric constant. [Technical means of solving the problem]

[0008] The inventors found that: By adopting antimony oxide as a clarifier and by prescribing a range of T-SnO 2 content ratios (T-SnO 2 is the total tin oxide converted to SnO

[0009] The glass composition of the present invention, expressed in % by mass, contains the following components: 45≦SiO 2≦80、 10≦B 2O 3≦40、 0.1≦Al 2O 3≦20、 0.1≦(MgO+CaO)≦10、 0≦(Li 2O+Na 2O+K 2O)≦5、 0.1≦T-SnO 2≦2 (where, T-SnO 2 is converted to peroxide of SnO 2 ); and Based on quality, 0≦MgO / (MgO+CaO)≦0.50 is established.

[0010] The fiberglass of the present invention is a fiberglass constituted from the above-mentioned glass compositions.

[0011] The method for manufacturing glass fiber of the present invention includes the following steps: melting the glass composition of the present invention; and shaping the melted glass composition into glass fiber. [Effects of the Invention]

[0012] According to the present invention, a glass composition capable of stably manufacturing glass fibers with a low dielectric constant can be obtained. Furthermore, a glass composition that emits light upon irradiation with ultraviolet light can be obtained. The light emission caused by ultraviolet irradiation can be used as a pigment, sensor material, lighting material, building material, etc. Simple Explanation of the Diagram

[0013] none Implementation

[0014] The following describes embodiments of the present invention, but this description is not intended to limit the invention to specific embodiments. Hereinafter, "substantially free of" means a content of less than 0.1% by mass, preferably less than 0.05% by mass, more preferably less than 0.01% by mass, even more preferably less than 0.005% by mass, particularly preferably less than 0.003% by mass, and most preferably less than 0.001% by mass. "Substantially constitutes" means that the scope of "substantially free of" includes components other than those described, such as impurities unavoidably introduced from industrial raw materials, manufacturing equipment, etc. Regarding the content, characteristics, and other preferred ranges of each component, the upper and lower limits described below can be arbitrarily combined.

[0015] [Glass composition] <Glass Composition> (SiO 2) Silicon dioxide (SiO2) is a component that forms the glass framework and is the main component of glass (the component with the highest content). Furthermore, SiO2 is a component that adjusts the devitrification temperature and viscosity during glass formation and also has the effect of reducing the dielectric constant. If the SiO2 content is 45% by mass or more and 80% by mass or less, the rise in the devitrification temperature of the glass is suppressed, and the melting point of the glass does not become excessively high, thus improving the uniformity of the raw material melting process. The lower limit of the SiO2 content is preferably 48% by mass or more, more preferably 50% by mass or more, and may also be 51% by mass or more, 52% by mass or more, 53% by mass or more, 54% by mass or more, and even more preferably 55% by mass or more. The upper limit of the SiO2 content is preferably 75% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, particularly preferably 60% by mass or less, and most preferably 58% by mass or less. The SiO2 content can also be above 48% by mass and below 55% by mass.

[0016] (B₂O₃) Boron trioxide (B₂O₃) is a component that forms the glass framework. Furthermore, B₂O₃ is also a component that adjusts the devitrification temperature and viscosity during glass formation, and it has the effect of reducing the dielectric constant. On the other hand, B₂O₃ is easily volatilized when the glass composition melts; if its content is too high, the glass composition will be difficult to achieve sufficient homogeneity. Also, if the B₂O₃ content is excessive, the water resistance of the glass decreases. If the B₂O₃ content is 10% by mass or more and 40% by mass or less, the rise in the devitrification temperature of the glass is suppressed, and the melting point of the glass does not become too high, thus improving the homogeneity of the raw material during melting. Furthermore, if the content is within this range, the water resistance of the glass increases. The lower limit of the B₂O₃ content is preferably 15% by mass or more, more preferably 20% by mass or more, more preferably 24% by mass or more, particularly preferably 25% by mass or more, and most preferably greater than 26% by mass. The upper limit of the B2O3 content is preferably 35% by mass or less, more preferably 32% by mass or less, further preferably 30% by mass or less, especially preferably 29% by mass or less, and may also be 28% by mass or less. The B2O3 content may also be 29% by mass or more, depending on the circumstances.

[0017] (Al₂O₃) Alumina (Al₂O₃) is a component that forms the glass framework. Furthermore, Al₂O₃ is also a component that adjusts the devitrification temperature and viscosity during glass formation, and improves the water resistance of the glass. Moreover, Al₂O₃ is a component that adjusts the dielectric constant of the glass. If the content of Al₂O₃ is 0.1% by mass or more and 20% by mass or less, the rise in the devitrification temperature of the glass is suppressed, and the water resistance of the glass is increased. Furthermore, the melting point of the glass does not become excessively high, thus improving the uniformity of the raw material melting process. The lower limit of the Al₂O₃ content is preferably 1% by mass or more, more preferably 5% by mass or more, more preferably 8% by mass or more, particularly preferably 10% by mass or more, and most preferably 12% by mass or more. The upper limit of the content of Al2O3 is preferably 18% by mass or less, more preferably 16% by mass or less, and even more preferably 15% by mass or less, or 14% by mass or less, or even 13% by mass or less.

[0018] (MgO, CaO) Magnesium oxide (MgO) and calcium oxide (CaO) are components that maintain the heat resistance of glass and adjust the devitrification temperature and viscosity during glass formation. Furthermore, MgO and CaO improve the water resistance of glass. Finally, MgO and CaO adjust the dielectric constant of glass.

[0019] When considering the dielectric constant and water resistance of glass components, the sum of the contents of MgO and CaO (MgO + CaO), which are components used to adjust the dielectric constant and water resistance of the glass, is particularly important. If the sum of the contents of MgO and CaO (MgO + CaO) is 0.1% by mass or more and 10% by mass or less, the rise in the devitrification temperature of the glass is suppressed, and the melting point of the glass does not become too high, thus improving the uniformity of the raw material melting. Furthermore, if the sum of the contents is within this range, the water resistance of the glass becomes higher. The lower limit of the sum of the contents of MgO and CaO (MgO + CaO) is preferably 1% by mass or more, more preferably 1.5% by mass or more, more preferably 2% by mass or more, particularly preferably 2.5% by mass or more, and most preferably 3% by mass or more. The upper limit of the sum of MgO and CaO content (MgO+CaO) is preferably below 8% by mass, but it can also be below 7% by mass, below 6% by mass, below 5% by mass, and even below 4.5% by mass.

[0020] Adding MgO and adding CaO can achieve the same effect, but from the perspective of further reducing the dielectric constant, adding MgO is more advantageous than adding CaO. Furthermore, from the perspective of further improving water resistance, adding MgO is more advantageous than adding CaO. However, from the perspective of suppressing phase separation in glass, in the case of glass fibers with a low dielectric constant, adding CaO may be more advantageous than adding MgO. Phase separation in glass can sometimes impair the homogeneity of the glass and can sometimes make glass fiber spinning difficult. When this aspect should be emphasized, it is preferable to add MgO and CaO in the following manner: based on mass, 0≦MgO / (MgO+CaO)≦0.50, further 0≦MgO / (MgO+CaO)≦0.25, especially 0≦MgO / (MgO+CaO)<0.21, and 0≦MgO / (MgO+CaO)≦0.2 is valid as appropriate.

[0021] MgO is a component that maintains the heat resistance of glass while adjusting the devitrification temperature and viscosity during glass formation. Furthermore, MgO enhances the water resistance of glass. Additionally, MgO adjusts the dielectric constant of glass. Moreover, MgO suppresses phase separation in glass. On the other hand, if the MgO content is too high, the dielectric constant of the glass increases. Therefore, the lower limit of the MgO content can be 0.1% by mass or more, or 0.5% by mass or more, 1% by mass or more, 1.5% by mass or more, 2% by mass or more, or 2.5% by mass or more. The upper limit of the MgO content can be 10% by mass or less, or 8% by mass or less, 6% by mass or less, less than 5% by mass, 4.5% by mass or less, 4% by mass or less, and even 3% by mass or less.

[0022] CaO is a component that maintains the heat resistance of glass while adjusting the devitrification temperature and viscosity during glass formation. Furthermore, CaO improves the water resistance of glass. Moreover, CaO adjusts the dielectric constant of glass. Additionally, CaO suppresses phase separation in glass. On the other hand, if the CaO content is too high, the dielectric constant of the glass increases. Therefore, the lower limit of CaO content can be 0.1% by mass or more, or 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, or 4% by mass or more. The upper limit of CaO content can be 10% by mass or less, or 8% by mass or less, 6% by mass or less, or even less than 5% by mass. When particular emphasis is placed on adjusting the dielectric constant of the glass composition, the upper limit of CaO content can also be less than 4% by mass, less than 2% by mass, or even less than 1% by mass.

[0023] (SrO) The glass composition may further contain strontium oxide (SrO). SrO is a component that adjusts the devitrification temperature and viscosity during glass formation. Furthermore, SrO is a component that suppresses phase separation in the glass. On the other hand, if too much SrO is present, the dielectric constant of the glass increases. Therefore, the upper limit of the SrO content can be 5% by mass or less, or it can be 3% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, and even less than 0.1% by mass. SrO may also be substantially absent. However, in certain embodiments, especially those where MgO is 1% by mass or less, surprisingly, by containing an appropriate amount of SrO, the dielectric constant decreases, contrary to expectations. The SrO content exhibiting this effect is 1% by mass or more, or 2% by mass or more.

[0024] (BaO) The glass composition may further contain barium oxide (BaO). BaO is a component that adjusts the devitrification temperature and viscosity during glass formation. Furthermore, BaO is a component that inhibits phase separation in the glass. On the other hand, if the content of too much BaO is excessive, the dielectric constant of the glass increases. Therefore, the upper limit of the BaO content can be less than 5% by mass, or less than 2% by mass, less than 1% by mass, less than 0.5% by mass, and even less than 0.1% by mass. BaO may also be substantially absent. When particular emphasis is placed on the uniform melting of glass raw materials and the stable manufacturing of glass compositions, the lower limit of the BaO content can be more than 0.05% by mass, more than 0.1% by mass, for example, more than 0.1% by mass but less than 1% by mass, and even more than 0.2% by mass but less than 1% by mass.

[0025] (ZnO) The glass composition may further contain zinc oxide (ZnO). ZnO is a component that adjusts the devitrification temperature and viscosity during glass formation. Furthermore, ZnO is a component that adjusts the dielectric constant of the glass. On the other hand, if too much ZnO is present, the dielectric constant of the glass increases. Therefore, the upper limit of the ZnO content can be less than 5% by mass, or less than 2% by mass, less than 1% by mass, less than 0.5% by mass, and even less than 0.1% by mass. ZnO may also be substantially absent.

[0026] (Li₂O, Na₂O, K₂O) Alkali metal oxides (Li₂O, Na₂O, K₂O) are components that maintain the heat resistance of glass while adjusting the devitrification temperature and viscosity during glass formation.

[0027] Li₂O is a component used to adjust the devitrification temperature and viscosity during glass formation. On the other hand, excessive Li₂O increases the dielectric constant of the glass. Furthermore, excessive Li₂O reduces the water resistance of the glass. Therefore, the lower limit of the Li₂O content can be 0.1% by mass or more, or 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, and even 0.5% by mass or more. The upper limit of the Li₂O content can be 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, 1.5% by mass or less, and even 1% by mass or less.

[0028] Na₂O is a component used to adjust the devitrification temperature and viscosity during glass formation. On the other hand, if there is too much Na₂O, the dielectric constant of the glass will increase. Also, if there is too much Na₂O, the water resistance of the glass will decrease. Therefore, the upper limit of the Na₂O content can be 4% by mass or less, or it can be 2% by mass or less, 1.5% by mass or less, 1% by mass or less, 0.5% by mass or less, and even 0.2% by mass or less.

[0029] K₂O is a component used to adjust the devitrification temperature and viscosity during glass formation. On the other hand, excessive K₂O increases the dielectric constant of the glass. Furthermore, excessive K₂O reduces the water resistance of the glass. Therefore, the upper limit for K₂O content can be below 4% by mass, or below 2%, 1%, 0.5%, 0.2%, and even less than 0.1% by mass. K₂O may also be virtually absent.

[0030] The lower limit of the total content of alkali metal oxides (Li₂O + Na₂O + K₂O) can be 0.1% by mass or more, or 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, and further, 0.5% by mass or more. The upper limit of (Li₂O + Na₂O + K₂O) can be 5% by mass or less, or 4% by mass or less, 3% by mass or less, 2% by mass or less, 1.5% by mass or less, and further, 1% by mass or less. Alkali metal oxides (Li₂O + Na₂O + K₂O) may also be substantially absent. However, when particular emphasis is placed on the uniform melting of glass raw materials and the stable manufacturing of glass compositions, (Li₂O + Na₂O + K₂O) may be 1% by mass or more.

[0031] The lower limit of the ratio of alkali metal oxide content (Li₂O / (Li₂O+Na₂O)) expressed as a percentage by mass, Li₂O / (Li₂O+Na₂O), can be 0.01 or higher, or 0.02 or higher, or 0.05 or higher. The upper limit of Li₂O / (Li₂O+Na₂O) can be 0.9 or lower, or 0.8 or lower, or 0.6 or lower. When this ratio is within these ranges, the operating temperature is significantly reduced, which is beneficial for workability and equipment design. This effect is well known as a mixed alkali effect, but the well known mixed alkali effect is for cases where the alkali metal oxide content exceeds, for example, 10% by mass. It is unknown when the alkali metal oxide content is 5% by mass or lower. Furthermore, it should be noted that, in particular, this low-alkali mixed alkali effect is clearly exhibited whenever the ratio changes from 0 to 0.01.

[0032] (TiO 2) The glass composition may further contain titanium dioxide (TiO2). TiO2 is a component that improves the melt flowability and chemical durability of the glass, as well as its ultraviolet absorption properties. On the other hand, if the glass contains too much TiO2, the dielectric constant of the glass will increase. The lower limit of the TiO2 content can be 0.1% by mass or more. The upper limit of the TiO2 content can be 5% by mass or less, or 2% by mass or less, less than 1% by mass, less than 0.5% by mass, or less than 0.2% by mass. Within these upper limits, the increase in devitrification temperature due to the presence of TiO2 can be suppressed. The upper limit of the TiO2 content can also be less than 0.1% by mass. TiO2 may also be substantially absent.

[0033] (ZrO 2) The glass composition may further contain zirconium oxide (ZrO2). ZrO2 is a component used to adjust the devitrification temperature and viscosity during glass formation. On the other hand, if too much ZrO2 is present, the dielectric constant of the glass will increase. The upper limit of the ZrO2 content can be less than 5% by mass, or less than 2% by mass, less than 1% by mass, less than 0.5% by mass, less than 0.2% by mass, and even less than 0.1% by mass. Within these upper limits, the increase in the devitrification temperature of the molten glass that affects the manufacture of the glass composition due to the presence of ZrO2 can be suppressed. ZrO2 may also be substantially absent.

[0034] (T-Fe₂O₃) Glass compositions may contain iron oxide. The iron (Fe) in glass compositions typically exists in the form of Fe²⁺ or Fe³⁺. Fe³⁺ enhances the ultraviolet absorption properties of the glass composition, while Fe²⁺ enhances its thermal absorption properties. Even without intentional Fe inclusion, Fe may inevitably be introduced due to industrial raw materials. A lower Fe content can prevent coloration of the glass composition. The upper limit for Fe content is expressed by T-Fe₂O₃ (T-Fe₂O₃ is the total iron oxide converted to Fe₂O₃), and can be less than 5% by mass, less than 2% by mass, less than 1% by mass, less than 0.5% by mass, and even less than 0.2% by mass. T-Fe₂O₃ can be 0.1% by mass or more. Depending on the glass composition, T-Fe₂O₃ can sometimes enhance the clarifying effect of T-SnO₂. Specifically, if the glass composition contains 0.1% by mass or more of T-Fe₂O₃, for example, 0.1% by mass or more but less than 1% by mass, and 0 ≤ MgO / (MgO+CaO) ≤ 0.2, and further 0 ≤ MgO / (MgO+CaO) ≤ 0.15, then it is particularly suitable for stable manufacturing. In this particularly suitable glass composition, the content of T-SnO₂ can also be 0.15% by mass or more, and further, 0.2% by mass or more. Since T-Fe₂O₃ has a strengthening effect, it can be stably manufactured even if, for example, it does not reach 0.5% by mass.

[0035] (T-SnO 2) The glass composition of this embodiment contains tin oxide. Sn in the glass typically exists in the form of Sn²⁺ and / or Sn⁴⁺. SnO₂ is a component that defoams bubbles present in the glass preform. It also improves the water resistance of the glass. Furthermore, the Sn in the glass is a component that emits light when exposed to ultraviolet light. Regarding tin oxide in the glass composition, the content of T-SnO₂ (converted to total tin oxide of SnO₂) is set to a range of 0.1% by mass or more and 2% by mass or less. If the content of T-SnO₂ is less than 0.1% by mass, sufficient clarification of the glass composition due to tin oxide cannot be obtained. If the content of T-SnO₂ exceeds 2% by mass, the devitrification temperature of the glass composition increases, or the glass is prone to phase separation.

[0036] The lower limit of the content of T-SnO2 is preferably 0.1% by mass or more, and may also be 0.2% by mass or more, 0.22% by mass or more, 0.25% by mass or more, 0.3% by mass or more, 0.35% by mass or more, 0.4% by mass or more, and further may be 0.5% by mass or more. The lower limit of the content of T-SnO2 is preferably 0.6% by mass or more, and further may be 0.65% by mass or more, and may be 0.8% by mass or more, depending on the circumstances. The upper limit of the content of T-SnO2 is preferably 1.8% by mass or less, more preferably 1.6% by mass or less, further preferably 1.4% by mass or less, 1.3% by mass or less, less than 1.2% by mass, particularly preferably 1.0% by mass or less, 0.8% by mass or less, and most preferably 0.5% by mass or less, 0.3% by mass or less.

[0037] In one example of a glass composition suitable for the stable manufacture of glass fibers with low dielectric constant, the content of T-SnO2 is 0.5% by mass or more, and 0 ≤ MgO / (MgO+CaO) ≤ 0.2 is satisfied. This glass composition example may contain T-Fe2O3 within the above range, or may substantially not contain it. This glass composition example may contain CeO3 within the following range, or may substantially not contain it.

[0038] In another example of a glass composition suitable for the stable manufacture of glass fibers with low dielectric constants, the content of T-SnO2 is 0.3% by mass or more, and further 0.4% by mass or more, and it is substantially free of MgO. This glass composition may also contain T-Fe2O3 within the above-mentioned range, or it may be substantially free of it. This glass composition may also contain CeO3 within the following range, or it may be substantially free of it.

[0039] Furthermore, in another example of a glass composition suitable for stably manufacturing glass fibers with low dielectric constants, the content of T-SnO2 is 0.6% by mass or more, and further 0.65% by mass or more, particularly 0.7% by mass or more, and depending on the case, 0.8% by mass or more, and includes (Li₂O + Na₂O + K₂O) in the range of 0.3% by mass or more, and further 0.35% by mass or more. This example of a glass composition may also contain T-Fe₂O₃ within the above-mentioned range, or may substantially not contain it. This example of a glass composition may also contain CeO₃ within the following range, or may substantially not contain it.

[0040] To stably manufacture glass fibers with low dielectric constants, it is preferable to have a larger ΔT. In one example of a glass composition suitable for ensuring a larger ΔT, the following equations hold true based on mass. 0.1≦T-SnO 2≦0.5 0.1≦(T-Fe 2O 3+T-SnO 2)≦0.6 0.1≦(Li₂O+Na₂O+K₂O)≦1 The glass composition that achieves the above-mentioned conditions is suitable for achieving the following characteristics: a dielectric constant of 5.0 or less at 1 GHz, and further of 4.8 or less, and a ΔT of 100°C or more, and further of 140°C or more.

[0041] Components not shown in the above formulas will also affect ΔT. However, within the range where the above three formulas hold, even when components that are not ideal for low dielectric constants are included, such as when the fourth formula below holds simultaneously with the above three formulas, it is still possible to have both a lower dielectric constant and a higher ΔT. 0.1≦(SrO+BaO)≦5

[0042] (CeO 2) The glass composition may further contain cerium oxide (CeO2). CeO2 is a clarifying component. If the content of CeO2 is low, it can prevent the coloring of the glass composition. Therefore, the lower limit of the CeO2 content can be 0.1% by mass or more. The upper limit of the CeO2 content can be 5% by mass or less, or 2% by mass or less, 1% by mass or less, or less than 0.5% by mass. The upper limit of the CeO2 content can also be less than 0.1% by mass. CeO2 may also be substantially absent.

[0043] (F2, Cl2) The glass composition may further contain fluorine and / or chlorine. Fluorine or chlorine can be contained in the form of molecules (F₂ or Cl₂, respectively) or in the form of anions (F⁻ or Cl⁻, respectively). In this specification, fluorine or chlorine contained in the form of molecules or anions are sometimes collectively referred to as F₂ or Cl₂, respectively. Furthermore, their content is expressed as a percentage by mass converted to molecules. Fluorine (F₂) is highly volatile and may disperse when molten, and its content in the glass is difficult to manage. The upper limit of the F₂ content can be less than 5% by mass, or less than 2% by mass, less than 1% by mass, less than 0.5% by mass, less than 0.2% by mass, and even less than 0.1% by mass. F₂ may also be substantially absent. Chlorine (Cl₂) is highly volatile and may disperse when molten, and its content in the glass is also difficult to manage. The maximum content of Cl2 can be less than 5% by mass, or less than 2% by mass, less than 1% by mass, less than 0.5% by mass, less than 0.2% by mass, and even less than 0.1% by mass. Cl2 may also be substantially absent.

[0044] (P₂O₅) Glass composition may further contain phosphorus pentoxide (P₂O₅). Phosphorus pentoxide is a component that forms the glass framework and also adjusts the devitrification temperature and viscosity during glass formation. Furthermore, P₂O₅ is a component that adjusts the dielectric constant of the glass. Generally, if the P₂O₅ content exceeds 2% by mass, the furnace walls of the melting furnace and regenerator will be eroded during glass melting, significantly reducing the furnace life. The upper limit for P₂O₅ content can be below 5% by mass, or below 2% by mass, less than 1% by mass, less than 0.5% by mass, less than 0.2% by mass, and even less than 0.1% by mass. P₂O₅ may also be substantially absent.

[0045] (Other ingredients) The glass composition may contain at least one of the following as other components, selected from La₂O₃, WO₃, Nb₂O₅, Y₂O₃, MoO₃, Ta₂O₅, MnO₂, Cr₂O₃, CuO, and CoO, at a concentration of 0% to 5% by mass. The permissible concentrations of these components may be less than 2% by mass, less than 1% by mass, less than 0.5% by mass, or even less than 0.1% by mass. The total permissible concentrations of these components may be less than 5% by mass, less than 2% by mass, less than 1% by mass, less than 0.5% by mass, or even less than 0.1% by mass. However, the aforementioned other components may also be substantially absent.

[0046] The glass composition may contain at least one of Br2, I2, As2O3, and Sb2O3 as an additive at a content of 0% to 1% by mass. The permissible content of these components may be less than 0.5% by mass, less than 0.2% by mass, or less than 0.1% by mass. The total permissible content of these components may be less than 1% by mass, less than 0.5% by mass, less than 0.2% by mass, or less than 0.1% by mass. However, the other components mentioned above may be substantially absent.

[0047] The glass composition may contain H₂O, OH, H₂, CO₂, CO, He, Ne, Ar, and N₂ at a concentration of 0% to 0.1% by mass, respectively. The permissible concentrations of these components may be less than 0.05% by mass, less than 0.03% by mass, or even less than 0.01% by mass. The total permissible concentrations of these components may be less than 0.1% by mass, less than 0.05% by mass, less than 0.03% by mass, or even less than 0.01% by mass. However, the other components mentioned above may also be substantially absent.

[0048] The glass composition may also contain trace amounts of precious metal elements. For example, it may contain precious metal elements such as Pt, Rh, Au, and Os at a concentration of 0% to 0.1% by mass. The permissible concentrations of these elements may be less than 0.1% by mass, less than 0.05% by mass, less than 0.03% by mass, and even less than 0.01% by mass. The total permissible concentrations of these elements may be less than 0.1% by mass, less than 0.05% by mass, less than 0.03% by mass, and even less than 0.01% by mass. However, the other elements mentioned above may also be substantially absent.

[0049] <Characteristics> The following describes the characteristics that the glass composition of this embodiment may possess. (Melting characteristics) The temperature at which the viscosity of molten glass reaches 1000 dPa·sec (1000 poise) is called the operating temperature of that glass, which is the optimal temperature for glass forming. In the manufacture of glass fibers, an operating temperature above 1100°C can reduce the variation in glass fiber diameter. An operating temperature below 1450°C can reduce fuel costs during glass melting, reduce the risk of thermal corrosion to glass manufacturing equipment, and extend equipment life. The lower limit of the operating temperature can be above 1100°C, or above 1150°C, 1200°C, 1250°C, and even above 1300°C. The upper limit of the operating temperature can be below 1450°C, or below 1420°C, 1400°C, 1380°C, and even below 1350°C.

[0050] The larger the temperature difference ΔT obtained by subtracting the devitrification temperature from the operating temperature, the less likely devitrification will occur during glass forming, and the higher the yield of homogeneous glass can be. Therefore, ΔT can be above 0°C, or above 10°C, 20°C, 30°C, 40°C, or 50°C, and depending on the situation, it can also be above 100°C, and even above 140°C. On the other hand, if ΔT is below 500°C, it becomes easier to adjust the glass composition. ΔT can be below 500°C, or below 400°C, 300°C, and even below 200°C.

[0051] (Dielectric constant) The glass composition of this embodiment can have a low dielectric constant. The dielectric constant measured at a frequency of 1 GHz is 5.5 or less, 5.2 or less, 5.0 or less, 4.9 or less, 4.8 or less, 4.7 or less, 4.6 or less, and further, 4.5 or less, and depending on the situation, 4.4 or less. Strictly speaking, dielectric constant refers to relative dielectric constant; in this specification, it is conventionally stated only as dielectric constant. The dielectric constant is a value at room temperature (25°C).

[0052] [glass fiber, etc.] <glass fiber> The glass fiber in this embodiment is composed of the aforementioned glass composition. According to this embodiment, even when the fiber diameter is small, devitrification and air bubble incorporation in the glass fiber can be further suppressed. Therefore, the glass fiber in this embodiment can be a glass fiber with a small fiber diameter.

[0053] The average fiber diameter of the glass fiber is, for example, 1 to 6 μm. The average fiber diameter can be 3 μm or more, and can be 4.6 μm or less, and further can be 4.3 μm or less. Glass compositions with characteristic temperatures suitable for mass production are suitable for stable manufacturing in the form of finer glass fibers. In a preferred form, the average fiber diameter is even finer, for example, 3.9 μm or less, and further 3.5 μm or less. The glass fiber is, for example, long glass fibers (filaments).

[0054] As a preferred application of the glass fiber in this embodiment, printed circuit boards can be cited as an example. Glass fibers with low dielectric constant and small fiber diameter are suitable for use in printed circuit boards. However, the application is not limited to printed circuit boards.

[0055] Glass fibers can be made into glass yarn. The glass yarn of this embodiment may contain glass fibers other than those of this embodiment, or it may be composed only of the glass fibers of this embodiment, specifically long glass fibers. This glass yarn suppresses defects such as breakage and fuzzing of glass fibers, and has high productivity.

[0056] The number of long glass fibers (filament count) contained in the glass fiber cloth is, for example, 30 to 200. When used for printed circuit boards, the number of filaments can be, for example, 30 to 100, 30 to 70, or even 30 to 60. An appropriate number of filaments makes it easier and more reliable to form the glass cloth, which is advantageous for achieving thinner printed circuit boards. However, the composition and application of glass fiber cloth are not limited to these examples.

[0057] The fiberglass yarn containing glass fibers can have a count of 1 to 6 tex, or even 1 to 3 tex. An appropriate count makes it easier and more reliable to form a thinner glass cloth, which is advantageous for achieving thinner printed circuit boards.

[0058] The strength of the glass yarn can be 0.4 N / tex or higher, and even 0.6 N / tex or higher, and especially 0.7 N / tex or higher.

[0059] The glass fibers of this embodiment can be manufactured using known methods. For example, when manufacturing glass fibers with an average fiber diameter of about 1 to 6 μm, the following method can be used: A glass composition is placed in a glass melting furnace and melted to form molten glass. The molten glass is then drawn out from multiple spinning nozzles located at the bottom of a heat-resistant bushing in a spinning furnace, forming filaments. Glass fibers can be manufactured in this way. The glass fibers can be long glass fibers (filaments). The melting temperature in the melting furnace is, for example, 1300 to 1700°C, preferably 1400 to 1700°C, and more preferably 1500 to 1700°C. In such cases, even if the formed glass fibers have a small fiber diameter, it is possible to further suppress minute devitrification and the incorporation of air bubbles in the glass fibers, and to prevent excessive spinning tension, thereby reliably ensuring the properties (e.g., strength) and quality of the obtained glass fibers.

[0060] To manufacture glass fibers with smaller diameters, methods such as increasing the speed at which molten glass is drawn from the spinning furnace or decreasing the temperature of the spinning nozzle are considered. However, in the former method, it is sometimes impossible to ensure sufficient time for defoaming of the molten glass within the spinning furnace. Therefore, the introduction of air bubbles can sometimes lead to fiber breakage and reduced fiber strength during spinning. Furthermore, the tension generated during spinning (spinning tension) increases with the spinning speed, which can also sometimes cause fiber breakage, reduced fiber strength, and decreased fiber quality. Typically, glass fibers are wound using a rotating winding device called a collet. If the spinning tension is excessively increased, the wound glass fibers will knot due to indentations between the fingers, leading to a decrease in fiber quality. Furthermore, the collet is a device with a plurality of fingers on the outer periphery of the collet body. These fingers move radially outward when the collet rotates and sink into the collet body side when the collet stops. A decrease in the quality of the glass fiber can sometimes lead to poor appearance and / or poor fiber opening of the glass cloth. On the other hand, in the latter method, the melting temperature in the melting furnace must also be lowered, which sometimes results in the melting temperature approaching the devitrification temperature of the glass composition, causing the viscosity of the molten glass to increase and making sufficient defoaming impossible. As the viscosity increases, the spinning tension also increases, thus also causing the aforementioned problems.

[0061] If the glass composition of this embodiment is used and melted within the aforementioned temperature range, the above-mentioned problems can be alleviated. Due to the improved quality of the glass fiber, the appearance and / or fiber opening properties of the glass cloth using this glass fiber also become better.

[0062] A clustering agent is applied to the surface of the fiberglass formed by spinning, thereby forming a glass strand by a number of fiberglass fibers, such as 10~120 fiberglass bundles. The bundle comprises fiberglass of this embodiment. The bundle is wound around a tube body (e.g., a paper tube tube body) on a high-speed rotating cylinder to make a block (cake), then the bundle is rewinded from the outer layer of the block, one side is added and the other side is air-dried, and rolled back to the curling shaft.

[0063] [glass cloth] The glass cloth of this embodiment is constructed of glass fiber as described above. The glass cloth of this embodiment may also have such characteristics as a low dielectric constant that the glass composition of this embodiment has. The fabric structure of the glass fabric of this embodiment is, for example, plain weave, ribbon weave, diagonal weave, square flat weave, rib weave, preferably plain weave. However, fabric organization is not limited to those examples. The glass yarn may comprise a glass fiber other than the fiberglass of the present embodiment, or may consist of only a fiberglass fiber of the present embodiment, specifically consisting of only fiberglass fibers. The glass cloth of this embodiment inhibits the occurrence of breakage, linting and other disadvantages of the glass fiber and is more productive.

[0064] In the better one of the morphologies, the thickness of the glass cloth is represented by “thickness determined in accordance with the provisions of item 7.10.1 of JIS R3420:2013” ​​as less than 20 μm, 7~20 μm, and in turn 8~15 μm. The better form of glass cloth is suitable for thinning of the printed substrate.

[0065] In the better one morphology, the mass of glass cloth is expressed by “cloth mass determined in accordance with the provisions of item 7.2 of JIS R3420:2013” ​​as less than 20 g / m 2 , 8~20 g / m 2 , and in turn 8~13 g / m The better form of glass cloth is suitable for thinning printed substrates.

[0066] In one of the better forms, with respect to the number of roots (fabric density) of fiberglass per unit length (25 mm) of the glass fabric, both warp and weft yarns are, for example, 80~130, 80~110, and in turn 90~110 per 25 mm. The thinning of the thickness of the glass cloth of the better form increases the intersection of warp and weft yarns, the glass cloth is not prone to weft slant and is suitable for inhibiting the generation of pinholes when containing resin immersion.

[0067] In a preferred embodiment, the air permeability of the glass cloth is 200 cm³ / (cm²·s) or less, 50 to 200 cm³ / (cm²·s), and further 50 to 150 cm³ / (cm²·s). The glass cloth in this preferred embodiment is thinner, which is suitable for suppressing the formation of the aforementioned pinholes. Furthermore, in order to open the glass cloth with the aforementioned level of air permeability, the glass composition of this embodiment, or a glass raw material prepared in a manner that yields the glass composition of this embodiment, can be melted at the aforementioned temperature, i.e., 1400°C or higher, preferably 1400 to 1650°C, to obtain glass fibers.

[0068] The glass cloth of this embodiment can be manufactured using the glass fiber of this embodiment and employing known methods. One example of the manufacturing method is as follows: after performing a warping and sizing step on the glass yarn, it is woven into the weft yarn of the glass yarn as the warp. The weft yarn can be woven into the weft yarn using various looms, such as jet looms, Sulzer looms, and rapier looms. Specific examples of jet looms include air-jet looms and water-jet looms. However, the loom used to manufacture the glass cloth is not limited to these.

[0069] The glass cloth in this embodiment can also undergo a fiber-opening process. Fiber-opening is beneficial for achieving a thinner glass cloth. The specific method of fiber-opening is not particularly limited; for example, it can be performed using water pressure, high-frequency vibration with water as a medium, or pressure applied using rollers. Furthermore, the water used as the fiber-opening medium can be degassed water, ion-exchanged water, deionized water, electrolyzed cation water, or electrolyzed anion water. Fiber-opening can be performed simultaneously with the weaving of the glass cloth, or after weaving. Additionally, fiber-opening can be performed simultaneously with various treatments such as heat cleaning and surface treatment, or after various treatments.

[0070] When the woven glass cloth is contaminated with substances such as bubbling agents, a removal process, such as thermal cleaning, can be performed. When the glass cloth after removal treatment is used on a printed circuit board, the impregnation of the matrix resin and the adhesion to the resin become excellent. The woven glass cloth can also be surface-treated with a silane coupling agent, either after or separately from the removal treatment. Surface treatment can be performed using known methods, specifically, methods such as impregnating the glass cloth with a silane coupling agent, coating the glass cloth with a silane coupling agent, or spraying the glass cloth with a silane coupling agent.

[0071] The glass cloth of this embodiment is suitable for printed circuit boards. When used in printed circuit boards, it can effectively utilize the characteristics of being composed of glass fibers with low dielectric constant and small fiber diameter. However, its application is not limited to printed circuit boards.

[0072] [Prepreg] The prepreg of this embodiment can be made of the glass cloth of this embodiment. The prepreg of this embodiment can also possess the aforementioned characteristics, such as the low dielectric constant, of the glass composition of this embodiment. The manufacturing method of the prepreg of this embodiment is not particularly limited; any conventionally known manufacturing method may be used. The resin impregnated in the prepreg of this embodiment is not particularly limited; any synthetic resin capable of being compounded with the glass cloth of this embodiment may be used, such as thermosetting resins, thermoplastic resins, and composite resins thereof. Ideally, a resin with a low dielectric constant that is compounded with the glass cloth of this embodiment, which has a low dielectric constant, should be used.

[0073] [Printed substrate] The printed circuit board of this embodiment can be made of the glass cloth of this embodiment. The printed circuit board of this embodiment can also possess the aforementioned characteristics, such as the low dielectric constant, of the glass composition of this embodiment. The manufacturing method of the substrate of this embodiment is not particularly limited; any conventionally known manufacturing method can be used. For example, a method of curing a prepreg containing resin impregnated in glass cloth can be cited.

[0074] (Examples 1-21 and Comparative Examples 1-5) Common glass raw materials, such as silica fume, were mixed in as shown in Tables 1 to 3 to prepare batches of glass raw materials for each example and comparative example. Each batch was heated to 1550–1600°C in an electric furnace to melt it, and maintained in this state for approximately 4 hours until the composition became homogeneous. Subsequently, a portion of the molten glass (glass melt) was allowed to flow onto an iron plate and slowly cooled to room temperature in the electric furnace to obtain a bulk glass composition (plate, glass sample).

[0075] For the obtained glass composition, the relationship between viscosity and temperature was investigated using the standard platinum ball pulling method, and the operating temperature was determined based on the results. Here, the platinum ball pulling method is as follows: a platinum ball is immersed in molten glass, and the platinum ball is pulled up at a constant speed. The relationship between the load (resistance) and the gravity and buoyancy acting on the platinum ball is applied to Stokes' law, which describes the relationship between viscosity and descent velocity of small particles settling in a fluid, to determine the viscosity.

[0076] Glass components pulverized to a particle size of 1.0–2.8 mm are placed in a platinum boat and kept in an electric furnace with a temperature gradient (800–1400 °C) for 2 hours. The devitrification temperature is determined based on the highest temperature of the furnace corresponding to the location where crystallization occurs. When the glass becomes cloudy and crystallization cannot be observed, the highest temperature of the furnace corresponding to the location where cloudiness occurs is set as the devitrification temperature. Here, the particle size is measured using a sieving method. Furthermore, the temperature distribution within the furnace varies depending on the location (temperature distribution within the furnace) and is pre-determined. Glass components placed at specific locations within the furnace are heated at the pre-determined temperature of that specific location. The temperature difference ΔT is the difference obtained by subtracting the devitrification temperature from the operating temperature.

[0077] The dielectric constant at 1 GHz was determined using a dielectric constant measuring device employing the cavity resonator perturbation method. The measurement temperature was set at 25°C, and the sample size was a cuboid with a square base of 1.5 mm on each side and a height of 100 mm.

[0078] Furthermore, the number of bubbles was determined as follows: Batches of glass raw materials were prepared for each example and comparative example by mixing common glass raw materials such as silica fume. Using an electric furnace, 150 g of each batch was heated to a test temperature of 1600°C to melt it, and maintained at this state for 2 hours until the composition became homogeneous. Subsequently, a portion of the molten glass (glass melt) was allowed to flow onto an iron plate and slowly cooled to room temperature in the electric furnace to obtain a glass sample. The number of bubbles in the glass sample was observed using an optical microscope, and the number of bubbles per 100 g of glass was calculated. Glass with fewer than 2000 bubbles per 100 g was designated A; glass with more than 2000 but less than 5000 bubbles was designated B; glass with more than 5000 but less than 10000 bubbles was designated C; and glass with more than 10000 bubbles was designated D.

[0079] Furthermore, the glass composition was irradiated with an ultraviolet lamp with a wavelength of 254 nm, and the presence and color of light were observed visually.

[0080] The results of these measurements are shown in Tables 1 to 3.

[0081] [Table 1] Components (mass %) or physical properties Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 SiO 2 54.03 52.17 51.77 51.69 51.16 51.16 53.55 51.23 51.64 51.34 B 2O 3 26.52 29.43 26.53 26.50 26.98 26.46 27.04 27.02 27.52 27.08 Al₂O₃ 13.52 12.63 13.53 13.51 13.49 13.49 13.51 13.51 13.49 13.53 MgO 1.20 1.41 0.91 0.90 1.37 0.89 1.17 1.47 1.40 1.39 High 3.62 1.90 6.52 6.44 5.60 6.43 3.50 5.55 4.96 5.68 SrO But 1.49 But But But But But But But But Bag But But But But 0.44 But But But But But ZnO But But But But But But But But But 0.25 Li 2O 0.32 0.18 0.18 0.18 0.18 0.18 0.32 0.18 But 0.18 Na2O 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.38 0.09 K2O - - - - - - - - 0.14 - TiO2 - - - - - 0.61 - - - - T-Fe 2O 3 0.24 0.24 0.24 - - - 0.24 - 0.24 - T-SnO2 0.46 0.46 0.23 0.69 0.69 0.69 0.46 0.69 0.23 0.46 CeO 2 - - - - - - - 0.26 - - F2 - - - - - - 0.12 - - - Devitrification temperature [°C] 1242 1289 1051 1288 1320 1285 1242 1320 1111 1109 Operating temperature [°C] 1306 1339 1336 1337 1329 1326 1298 1343 1332 1326 ΔT[℃] 64 50 285 49 9 41 56 twenty three 221 217 Dielectric constant 4.6 4.4 4.8 4.8 4.8 4.9 4.5 4.8 4.8 4.8 Test temperature [°C] 1600 1600 1600 1600 1600 1600 1600 1600 1600 1600 Number of bubbles C C A B B B C B C C Luminous color blue and white blue and white blue and white blue and white blue and white blue and white blue and white blue and white blue and white blue and white

[0082] [Table 2] Components (mass %) or physical properties Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 Example 21 SiO 2 51.01 52.46 51.75 51.36 48.94 54.64 51.30 51.27 51.25 51.24 51.32 B 2O 3 26.38 24.84 27.58 27.62 27.30 26.83 30.20 30.18 30.17 30.17 30.21 Al₂O₃ 15.00 15.02 11.97 12.76 14.92 12.11 12.40 12.39 12.39 12.39 12.40 MgO 1.50 0.85 0.88 1.48 - 1.14 0.81 0.81 0.81 0.81 0.81 High 5.65 6.14 6:30 5.56 8.12 3.17 2.10 2.10 2.10 2.10 2.10 SrO But But But But But But 2.70 2.70 2.70 2.70 2.70 Bag But But But But But But 0.10 0.10 0.10 0.10 0.10 ZnO But But But But But But But But But But But Li 2O But 0.23 0.14 0.18 0.18 1.06 0.10 0.04 0.01 0.00 0.13 Na2O - - 0.09 0.09 0.09 0.10 0.09 0.21 0.27 0.30 0.03 K2O - - 0.14 - - - - - - - - TiO2 - - - - - - - - - - - T-Fe 2O 3 - - - - - 0.25 - - - - - T-SnO2 0.46 0.46 1.15 0.69 0.45 0.70 0.20 0.20 0.20 0.20 0.20 CeO 2 - - - 0.26 - - - - - - - F2 - - - - - - - - - - - Devitrification temperature [°C] 1313 1171 1336 1281 1020 1277 1157 1178 1177 1188 1178 Operating temperature [°C] 1330 1325 1346 1348 1231 1284 1344 1326 1334 1365 1350 ΔT[℃] 17 154 10 67 211 7 187 148 157 177 172 Dielectric constant 4.8 4.8 4.8 4.8 5.0 4.6 4.4 4.4 4.4 4.4 4.4 Test temperature [°C] 1600 1600 1600 1600 1600 1600 1600 1600 1600 1600 1600 Number of bubbles C C A C A B C B C C B Luminous color blue and white blue and white blue and white blue and white blue and white blue and white blue and white blue and white blue and white blue and white blue and white

[0083] [Table 3] Components (mass %) or physical properties Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 SiO 2 74.20 51.90 51.72 51.17 53.30 B 2O 3 22.00 26.60 26.51 26.23 27.68 Al₂O₃ 0.30 13.56 13.51 13.37 12.79 MgO - 0.93 0.91 0.82 2.16 CaO 0.50 6.68 6.59 5.87 2.66 SrO - - - - - BaO - - - - - ZnO - - - - - Li 2O 0.50 0.14 - 0.18 0.18 Na₂O 1.00 0.19 0.38 0.09 0.09 K 2O 1.50 - 0.14 - - TiO2 - - - - 0.61 T-Fe₂O₃ - - 0.24 - - T-SnO 2 - - - 2.27 - CeO 2 - - - - 0.53 F2 - - - - - Devitrification temperature [°C] - 1030 1040 >1308 1208 Operating temperature [°C] - 1331 1341 1308 1305 ΔT[℃] - 301 301 <0 97 Dielectric constant 4.1 4.8 4.9 4.8 4.5 Test temperature [°C] 1600 1600 1600 1600 1600 Number of bubbles D D D A D Luminous color - - - blue and white -

[0084] The temperature difference ΔT (operating temperature - devitrification temperature) of the glass compositions obtained in Examples 1-21 ranges from 7°C to 285°C. The dielectric constant of the glass compositions obtained in Examples 1-21 at a frequency of 1 GHz ranges from 4.4 to 5.0. The number of bubbles in the glass compositions obtained in Examples 1-21 ranges from A to C. In any of the glass compositions obtained in Examples 1-21, luminescence induced by ultraviolet light is visible.

[0085] On the other hand, the content of T-SnO2 in the glass composition obtained in Comparative Example 1 exceeds the composition range specified in this invention. Therefore, the number of bubbles, D, in the glass composition obtained in Comparative Example 1 is greater than the number of bubbles in the glass compositions obtained in Examples 1 to 21. Furthermore, no luminescence caused by ultraviolet light was observed in the glass composition obtained in Comparative Example 1.

[0086] The content of T-SnO2 in the glass composition obtained in Comparative Example 2 exceeds the composition range specified in this invention. Therefore, the number of bubbles (D) in the glass composition obtained in Comparative Example 2 is greater than the number of bubbles in the glass compositions obtained in Examples 1 to 21. Furthermore, no luminescence caused by ultraviolet light was observed in the glass composition obtained in Comparative Example 2.

[0087] The content of T-SnO2 in the glass composition obtained in Comparative Example 3 exceeds the composition range specified in this invention. Therefore, the number of bubbles (D) in the glass composition obtained in Comparative Example 3 is greater than the number of bubbles in the glass compositions obtained in Examples 1 to 21. Furthermore, no luminescence caused by ultraviolet light was observed in the glass composition obtained in Comparative Example 3.

[0088] The content of T-SnO2 in the glass composition obtained in Comparative Example 4 exceeds the composition range specified in this invention. Therefore, the ΔT of the glass composition obtained in Comparative Example 4 did not reach 0°C and was less than the ΔT of the glass compositions obtained in Examples 1 to 21.

[0089] The content of T-SnO2 in the glass composition obtained in Comparative Example 5 exceeds the composition range specified in this invention. Therefore, the number of bubbles, D, in the glass composition obtained in Comparative Example 5 is greater than the number of bubbles in the glass compositions obtained in Examples 1 to 21.

[0090] none

Claims

1. A glass composition, expressed as a percentage by mass, containing the following components: 45≦SiO2≦70, 26.38≦B2O3≦40, 0.1≦Al2O3≦20, 0.1≦(MgO+CaO)≦10, 0≦(Li2O+Na2O+K2O)≦5, 0.1≦T-SnO2≦2 (wherein T-SnO2 is tin oxide converted to SnO2), 1≦SrO≦3; and based on mass, 0≦MgO / (MgO+CaO)≦0.50 holds true.

2. A glass composition, expressed as a percentage by mass, containing the following components: 45≦SiO2≦70, 26.38≦B2O3≦40, 0.1≦Al2O3≦20, 0.1≦(MgO+CaO)≦10, 0≦(Li2O+Na2O+K2O)≦5, 0.1≦T-SnO2≦2 (wherein T-SnO2 is tin oxide converted to SnO2), 0.05≦BaO≦1; and based on mass, 0≦MgO / (MgO+CaO)≦0.50 holds true.

3. A glass composition, expressed as a percentage by mass, containing the following components: 45≦SiO2≦70, 26.38≦B2O3≦40, 0.1≦Al2O3≦20, 0.1≦(MgO+CaO)≦10, 0≦(Li2O+Na2O+K2O)≦5, 0.1≦T-SnO2≦2 (wherein T-SnO2 is tin oxide converted to SnO2), 0.12≦F2≦5; and based on mass, 0≦MgO / (MgO+CaO)≦0.50 holds true.

4. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 45≦SiO2≦65.

5. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 45≦SiO2≦65, 5≦Al2O3≦20.

6. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 0.1 ≦ (MgO + CaO) < 5.

7. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 0.1 ≤ T-SnO2 ≤ 0.

5.

8. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 0.1 ≦ (Li₂O + Na₂O + K₂O) ≦ 5.

9. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 0.1 ≤ Li₂O ≤ 5.

10. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 0.01 ≤ Li₂O / (Li₂O + Na₂O) ≤ 0.

9.

11. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 0 ≦ P₂O₅ ≦ 5.

12. A glass composition as claimed in any of claims 1 to 3, wherein, Expressed as a percentage by mass, 0.1 ≤ CeO2 ≤ 5.

13. A glass composition as claimed in any of claims 1 to 3, wherein, When the temperature at which the viscosity of the above-mentioned glass composition is 1000 dPa・sec is set as the operating temperature, the above-mentioned operating temperature is 1450°C or below.

14. A glass composition as claimed in any of claims 1 to 3, wherein, When the temperature at which the viscosity of the above-mentioned glass composition is 1000 dPa・sec is set as the operating temperature, the temperature difference ΔT obtained by subtracting the devitrification temperature from the above-mentioned operating temperature is 0°C or higher.

15. A glass composition as claimed in any of claims 1 to 3, wherein, The dielectric constant of the above-mentioned glass composition is 5.5 or less at a frequency of 1 GHz.

16. A glass composition, expressed as a percentage by mass, containing the following components: 45≦SiO2≦70, 24≦B2O3≦40, 0.1≦Al2O3≦20, 0.1≦(MgO+CaO)≦10, 0≦(Li2O+Na2O+K2O)≦5, 0.1≦T-SnO2≦2 (wherein T-SnO2 is tin oxide converted to SnO2), 1≦SrO≦3, 0≦P2O5≦2; and based on mass, 0≦MgO / (MgO+CaO)≦0.50 holds true.

17. A glass composition, expressed as a percentage by mass, containing the following components: 45≦SiO2≦70, 24≦B2O3≦40, 0.1≦Al2O3≦20, 0.1≦(MgO+CaO)≦10, 0≦(Li2O+Na2O+K2O)≦5, 0.1≦T-SnO2≦2 (wherein T-SnO2 is tin oxide converted to SnO2), 0.05≦BaO≦1, 0≦P2O5≦2; and based on mass, 0≦MgO / (MgO+CaO)≦0.50 holds true.

18. A glass composition, expressed as a percentage by mass, contains the following components: 45≦SiO2≦70, 24≦B2O3≦40, 0.1≦Al2O3≦20, 0.1≦(MgO+CaO)≦10, 0≦(Li2O+Na2O+K2O)≦5, 0.1≦T-SnO2≦2 (wherein T-SnO2 is tin oxide converted to SnO2), 0.12≦F2≦5, 0≦P2O5≦2; and based on mass, 0≦MgO / (MgO+CaO)≦0.50 holds true.

19. A glass fiber comprising the glass composition of any one of claims 1 to 3 and 16 to 18.

20. A method for manufacturing glass fiber, comprising the steps of: melting a glass composition according to any one of claims 1 to 3 and 16 to 18; and shaping the molten glass composition into glass fiber.