Composition for glass fibers and method for producing glass fibers

Abstract

Provided is a composition for glass fibers that demonstrate both a low dielectric constant and a low dielectric loss tangent and that have a low thermal expansion coefficient. Also provided is a method for producing glass fibers.　A glass composition is characterized by containing, in terms of mass%, 35-68% of SiO2, 0-40% of Al2O3, 5-40% of B2O3, 0-12% of P2O5, and 0-5.5% of Li2O + Na2O + K2O + MgO + CaO + SrO + BaO + ZnO, and further containing at least one selected from among TiO2, ZrO2, Fe2O3, MoO3, Cr2O3, SO3, SnO2, Pt, and Rh.

Description

Composition for glass fibers and method for producing glass fibers

[0001] This invention relates to a composition for glass fibers and a method for producing glass fibers.

[0002] With the development of various electronic devices that support the information industry, the demand for generation AI and data servers is increasing. Circuit components for electronic devices, which are becoming increasingly high-density and high-speed, require low dielectric constant and low dielectric loss tangent characteristics to minimize signal propagation delay due to dielectric loss (transmission loss, conduction loss, deformation loss, and vibration loss), as well as to prevent overheating of the substrate due to thermal loss. Examples of such electronic circuit boards include printed circuit boards and low-temperature fired substrates. Printed circuit boards are composite materials made by mixing glass fibers as a reinforcing material with resin and forming them into a sheet, while low-temperature fired substrates are made of SiO ２ Ya B ２ O ３ This product is made by firing a green sheet of composite powder, which is a mixture of powdered glass containing a large amount of [material name] and fillers such as silica.

[0003] In addition to the above, with the miniaturization of electronic devices and the increase in communication speed, there is a growing demand for low dielectric properties in resins used around circuit boards, components for communication equipment, and resin materials used in electronic device housings. Glass fibers used as reinforcing materials for these resin materials are also required to have low dielectric constant and low dielectric loss tangent. Furthermore, in the automotive industry, with the development of autonomous driving systems, it is anticipated that there will be a growing demand for glass fiber composite resins that are high-strength, lightweight, and possess low dielectric constant and low dielectric loss tangent properties as materials used in in-vehicle radar and cameras.

[0004] Glass fibers for printed circuit boards and resin reinforcement include glass characterized by low dielectric constant and low dielectric loss tangent, referred to as D-glass (for example, Patent Document 1), and SiO ２ -B ２ O ３ - Al ２ O ３ Glasses (for example, Patent Document 2) have been proposed that incorporate alkaline earth elements into the glass composition system, aiming to suppress phase separation and reduce alkali leaching.

[0005] Japanese Patent Application Laid-Open No. 63-2831, Japanese Patent Application Laid-Open No. 06-211543

[0006] Incidentally, the above-mentioned D glass has a property of being easily phase-separated into a silica-rich phase and an alkali borate-rich phase. Therefore, in a high-temperature and high-humidity environment, alkali metal elements and boric acid may dissolve in the moisture adsorbed on the glass surface, causing a decrease in the adhesiveness with the resin and a decrease in the fiber diameter due to the erosion of the glass fiber. In addition, D glass has poor glass meltability, and the bushing nozzle is easily clogged by unmelted substances, etc., and yarn breakage often occurs during spinning, making it difficult to manufacture glass fibers.

[0007] Also, the glass containing an alkaline earth metal element in the glass composition system of ２ -B ２ O ３ -Al ２ O ３ was able to compensate for the drawbacks of D glass because it does not contain alkali metal elements. However, there was a problem that the dielectric constant at 1 MHz was high and it was insufficient as a low dielectric constant characteristic.

[0008] In addition, printed wiring boards and semiconductor package substrates used in data servers and the like are composed of different materials such as glass fibers, resins, and semiconductors. However, since these materials have a large difference in thermal expansion coefficient and peeling occurs at the material interface when heated, there was a concern that the circuit would be disconnected. Therefore, it is considered preferable that the glass fiber mixed with the resin as a reinforcing material has a low thermal expansion coefficient.

[0009] An object of the present invention is to provide a composition for glass fibers that achieves both low dielectric constant and low dielectric tangent, and has a low thermal expansion coefficient, and a method for manufacturing glass fibers.

[0010] Hereinafter, each aspect of the composition for glass fibers that solves the above problems will be described.

[0011] The composition for glass fibers according to Aspect 1 of the present invention has, as a glass composition, in mass%, ２ 35 to 68% of SiO ２ O ３ 0 to 40% of Al ２ O３ 5-40%, P ２ O ５ 0-12%, Li ２ O + Na ２ O+K ２ It contains 0-5.5% of O + MgO + CaO + SrO + BaO + ZnO, and TiO ２ , ZrO ２ Fe ２ O ３ MoO ３ , Cr ２ O ３ SO ３ , SnO ２ The material is further characterized by containing at least one selected from Pt and Rh. In this way, it is possible to obtain glass fibers that have both a low dielectric constant and a low dielectric loss tangent, as well as a low coefficient of thermal expansion.

[0012] In the glass fiber composition of Embodiment 2, in Embodiment 1, Li is present in mass%. ２ O + Na ２ O+K ２ It is preferable to contain 0 to 0.3% of O + MgO + CaO + SrO + BaO + ZnO. By doing so, phase separation of the glass can be suppressed, and glass fibers that achieve both low dielectric constant and low dielectric loss tangent can be obtained.

[0013] In the glass fiber composition of Embodiment 3, in Embodiment 1 or Embodiment 2, Li is present in mass%. ２ O + Na ２ O+K ２ It is preferable to contain 0.002 to 0.1% of O + MgO + CaO + SrO + BaO + ZnO. By doing so, phase separation of the glass can be suppressed, and glass fibers with both low dielectric constant and low dielectric loss tangent can be obtained.

[0014] The glass fiber composition according to embodiment 4 of the present invention, in embodiment 1, has a glass composition of SiO by mass %. ２ 45-57%, Al ２ O ３ 16-30%, B ２ O ３ 15-20.5%, P ２ O ５ 1-11.5%, SnO２ 0.0001-0.5%, Li ２ O + Na ２ O+K ２ It is characterized by containing 1 to 3.7% of O + MgO + CaO + SrO + BaO + ZnO. In this way, it is possible to obtain glass fibers that have both a low dielectric constant and a low dielectric loss tangent, as well as a low coefficient of thermal expansion and excellent productivity during glass fiber molding.

[0015] The glass fiber composition according to embodiment 5 of the present invention, in embodiment 1, has a glass composition of SiO in mass%. ２ 53-63%, Al ２ O ３ 5-15%, B ２ O ３ More than 20.5 to 31%, P ２ O ５ 0-5%, TiO ２ 0-5%, Li ２ O + Na ２ O+K ２ It is characterized by containing 1 to 5.1% of O + MgO + CaO + SrO + BaO + ZnO. By doing so, it is possible to obtain glass fibers that have both excellent low dielectric constant and low dielectric loss tangent, as well as a low coefficient of thermal expansion and excellent productivity during glass fiber molding.

[0016] In the glass fiber composition of embodiment 6, in any one embodiment of embodiments 1 to 3, SiO is present in mass%. ２ +B ２ O ３ It is preferable that the content be 40-95%. By doing so, phase separation of the glass can be suppressed, and glass fibers that have both low dielectric constant and low dielectric loss tangent can be obtained.

[0017] In the glass fiber composition of Embodiment 7, in any one embodiment of Embodiments 1 to 6, TiO is present in mass%. ２ It is preferable that the content be less than 0-2%. By doing so, phase separation of the glass can be suppressed, and glass fibers that have both low dielectric constant and low dielectric loss tangent can be obtained.

[0018] In the glass fiber composition of Embodiment 8, in any one embodiment of Embodiments 1 to 7, Na is present in mass ratio. ２ O / (Li ２ O + Na ２ O+K ２ It is preferable that O) is 0.001 to 1 or less. By doing so, phase separation of the glass can be suppressed, and glass fibers that have both low dielectric constant and low dielectric loss tangent can be obtained.

[0019] In the glass fiber composition of Embodiment 9, it is preferable that in any one embodiment of Embodiments 1 to 8, the dielectric constant ε at 25°C and 10 GHz is 6 or less, and the dielectric loss tangent tanδ is 0.008 or less. By doing so, transmission loss can be reduced and signal propagation delay can be suppressed.

[0020] In the glass fiber composition of embodiment 10, it is preferable that in any one embodiment of embodiments 1 to 9, the dielectric constant ε at 25°C and 40 GHz is 6 or less, and the dielectric loss tangent tanδ is 0.01 or less. By doing so, dielectric loss can be reduced and signal propagation delay can be suppressed.

[0021] In the glass fiber composition of Embodiment 11, it is preferable that the spinning temperature Tx is 1560°C or lower in any one embodiment of Embodiments 1 to 10. This extends the lifespan of fiber processing equipment such as bushings and reduces production costs. Furthermore, it makes it less likely for precious metal elements to leach from the fiber processing equipment and suppresses glass phase separation. Note that the spinning temperature Tx is the temperature at which the viscosity of the molten glass is 10 ３．０ This corresponds to the temperature at which the temperature becomes dPa·s.

[0022] In the glass fiber composition of embodiment 12, it is preferable that the Young's modulus E at 25°C is 30 GPa or more in any one embodiment of embodiments 1 to 11. By doing so, sufficient strength can be obtained in the glass fiber composite resin.

[0023] In the glass fiber composition of embodiment 13, in any one embodiment of embodiments 1 to 12, the coefficient of thermal expansion α at 50 to 200°C is 40 × 10 －７It is preferable that the temperature is below / °C. By doing so, damage due to temperature changes can be suppressed in the glass fiber composite resin.

[0024] In the glass fiber composition of Embodiment 14, in any one embodiment of Embodiments 1 to 13, it is preferable that the product of the thermal expansion coefficient α at 50 to 200°C and the dielectric loss tangent tanδ at 25°C and 10 GHz is 0.0009 to 0.2 or less. By doing so, it is possible to obtain glass fibers that have both a low dielectric constant and a low dielectric loss tangent, as well as a low thermal expansion coefficient.

[0025] In the glass fiber composition of Embodiment 15, it is preferable that, in any one embodiment of Embodiments 1 to 14, the weight loss rate after immersion in a 10% by mass hydrochloric acid solution at 80°C for 90 hours is 60% or less. By doing so, sufficient strength can be maintained even after the glass fiber composite resin has been subjected to moist heat treatment.

[0026] In the glass fiber composition of embodiment 16, it is preferable that, in any one embodiment of embodiments 1 to 15, the weight loss rate after immersion in a 10% by mass sodium hydroxide solution at 80°C for 16 hours is 50% or less. By doing so, sufficient strength can be maintained even after the glass fiber composite resin has been subjected to moist heat treatment.

[0027] The glass fiber according to embodiment 17 of the present invention is characterized by containing 95% by mass or more, on a solid content basis, of glass made from a glass fiber composition according to any one embodiment of embodiments 1 to 16.

[0028] The glass cloth according to aspect 18 of the present invention is characterized by containing glass fibers according to aspect 17.

[0029] The method for manufacturing glass fibers according to Aspect 19 of the present invention includes a step of preparing a glass raw material batch so that the glass fiber composition in any one of Aspects 1 to 16 can be obtained, a step of melting the glass raw material batch to obtain molten glass, and a step of forming the molten glass into a fibrous shape. By doing so, phase separation of the glass can be suppressed, and glass fibers having both a low dielectric constant and a low dielectric tangent can be obtained.

[0030] According to the present invention, it is possible to provide a glass fiber composition and a method for manufacturing glass fibers that achieve both a low dielectric constant and a low dielectric tangent and have a low coefficient of thermal expansion.

[0031] The glass fiber composition of the present invention has, as a glass composition, in mass %, SiO ２ 35 to 68%, Al ２ O ３ 0 to 40%, B ２ O ３ 5 to 40%, P ２ O ５ 0 to 12%, Li ２ O + Na ２ O + K ２ O + MgO + CaO + SrO + BaO + ZnO 0 to 5.5%, and further contains at least one selected from TiO ２ , ZrO ２ , Fe ２ O ３ , MoO ３ , Cr ２ O ３ , SO ３ , SnO ２ , Pt, Rh. Hereinafter, the glass fiber composition of the present invention will be described in detail. In the description of the content of each component in this specification, unless otherwise specified, "%" means "mass %".

[0032] (SiO ２ ) SiO ２ is a component that forms the network-like skeletal structure of the glass. It is also a component that reduces the dielectric constant ε and the dielectric tangent tan δ of the glass. SiO ２If the content is too low, it becomes difficult to obtain the effect of reducing the dielectric constant ε and the dielectric loss tangent tanδ. Therefore, for SiO ２ the lower limit of the content is preferably 40% or more, 45% or more, 45.5% or more, 46% or more, 46.5% or more, 47% or more, 47.5% or more, 48% or more, 48.5% or more, and particularly preferably 49% or more. On the other hand, if the content of SiO ２ is too high, the solubility of the raw materials decreases, and it becomes difficult to obtain a homogeneous glass. In addition to the increase in the spinning temperature Tx and the decrease in productivity, when attempting to improve productivity, it is necessary to add components for improving the meltability. Due to the influence of these components, the dielectric constant ε and the dielectric loss tangent tanδ tend to increase. Therefore, for SiO ２ the upper limit of the content is preferably 65% or less, 63% or less, 60% or less, 59.5% or less, 59% or less, 58.5% or less, 58% or less, 57.5% or less, 57% or less, and particularly preferably 56.5% or less.

[0033] (Al ２ O ３ ) Al ２ O ３ is a component that forms the network-like skeletal structure of the glass, either alone or together with P ２ O ５ or B ２ O ３ . It also suppresses the phase separation of the glass and is a component that lowers the high-temperature viscosity in the SiO ２ -B ２ O ３ -P ２ O ５ -based glass. The lower limit of the content of Al ２ O ３ is preferably 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, 11.5% or more, 12% or more, 12.5% or more, 13% or more, 13.5% or more, 14% or more, and particularly preferably 14.5% or more. On the other hand, if the content of Al ２ O ３ is too high, since the difference in electronegativity between aluminum atoms and oxygen atoms is large, the dielectric constant ε and the dielectric loss tangent tanδ tend to increase. Therefore, for Al ２ O ３The upper limit of the content is preferably 35% or less, 30% or less, 29.5% or less, 29% or less, 28.5% or less, 28% or less, 27.5% or less, 27% or less, 26.5% or less, 26% or less, 25.5% or less, 25% or less, and 24.5% or less, with 24% or less being particularly preferred.

[0034] (B ２ O ３ ) B ２ O ３ is SiO ２ Similarly, it is a component that forms the mesh-like skeletal structure of glass. It is also a component that reduces the dielectric constant ε and dielectric loss tangent tanδ of glass. B ２ O ３ If the content is too low, it becomes difficult to obtain the effect of lowering the dielectric constant ε and dielectric loss tangent tanδ of the glass. Therefore, B ２ O ３ The lower limit of the content is preferably 10% or more, 15% or more, 15.5% or more, 16% or more, 16.5% or more, 17% or more, 17.5% or more, and 18% or more, with 18.5% or more being particularly preferred. On the other hand, B ２ O ３ If the content is too high, the glass may become more prone to phase separation. Also, B on the surface ２ O ３ The formation of a rich phase can easily lead to crack formation on the surface, potentially making stable spinning difficult. Therefore, B ２ O ３ The upper limit of the content is preferably 35% or less, 34% or less, 33% or less, 32% or less, 31% or less, 30% or less, 25% or less, 24.5% or less, 24% or less, and 23.5% or less, with 23% or less being particularly preferred.

[0035] (P ２ O ５ ) P ２ O ５ Al ２ O ３ Ya B ２ O ３ It is also a component that forms the mesh-like skeletal structure of glass. Furthermore, because the difference in electronegativity between phosphorus and oxygen atoms is small, it is a component that reduces the dielectric constant ε and dielectric loss tangent tanδ of glass. P ２ O ５The lower limit of the content is preferably 0.5% or more, 1% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, 3.5% or more, 4% or more, 4.5% or more, 5% or more, and 5.5% or more, and particularly preferably 6% or more. On the other hand, P ２ O ５ If the content is too high, raw material costs may increase. Also, chemical resistance is easily reduced, and there is a risk of glass fiber erosion during chemical treatment such as Cu foil etching. Therefore, P ２ O ５ The upper limit of the content is preferably 11.5% or less, 11% or less, or 10.5% or less, and particularly preferably 10% or less.

[0036] (SiO ２ +B ２ O ３ ) SiO ２ and B ２ O ３ These are all components that reduce the dielectric constant ε and dielectric loss tangent tanδ of glass. The total amount of these components is SiO ２ +B ２ O ３ If the amount is too small, it becomes difficult to obtain the effect of lowering the dielectric constant ε and dielectric loss tangent tanδ of the glass. Also, the spinning temperature Tx will increase, which may increase production costs. Therefore, SiO ２ +B ２ O ３ The lower limit is preferably 40% or more, 45% or more, 50% or more, 51% or more, 52% or more, 53% or more, and 54% or more, with 55% or more being particularly preferred. On the other hand, SiO ２ +B ２ O ３ If there is too much of it, the glass will split into phases, and its chemical resistance will easily decrease. Therefore, SiO ２ +B ２ O ３ The upper limit is preferably 90% or less, 89% or less, 88% or less, 87% or less, 86% or less, 85% or less, 84% or less, 83% or less, 82% or less, 81% or less, or 80% or less, and is particularly preferably 79% or less.

[0037] (B ２ O ３ / (B ２ O ３ +P ２O ５ )) B ２ O ３ P ２ O ５ In the glass containing it, a three-coordinate planar structure may be formed. On the other hand, SiO ２ Because it forms a four-coordinate tetrahedron structure, SiO ２ It has as its main component and P ２ O ５ In glass containing B ２ O ３ If the content is too high, it can lead to uneven structure, making the glass more prone to phase separation. Therefore, B calculated in mole percent ２ O ３ and P ２ O ５ B relative to the total amount ２ O ３ Content ratio B ２ O ３ / (B ２ O ３ +P ２ O ５ If the value of ) is too large, there is a risk that the glass will be more prone to phase separation. Therefore, B ２ O ３ / (B ２ O ３ +P ２ O ５ The upper limit of the value of ) is preferably 1.0 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, and 0.89 or less, and particularly preferably 0.88 or less. On the other hand, B ２ O ３ If the content is too low, the dielectric constant ε and dielectric loss tangent tanδ of the glass tend to become high. Therefore, B ２ O ３ / (B ２ O ３ +P ２ O ５ The lower limit of the value of ) is preferably 0.5 or higher, 0.55 or higher, 0.57 or higher, 0.59 or higher, 0.6 or higher, 0.61 or higher, 0.62 or higher, 0.63 or higher, or 0.64 or higher, and particularly preferably 0.65 or higher.

[0038] (Li ２ O) Li ２O is a component that reduces the viscosity of glass. However, because the difference in electronegativity between lithium atoms and oxygen atoms is large and polarization is easily achieved, it is a component that easily increases the dielectric constant ε and dielectric loss tangent tanδ of glass. In addition, in high temperature and high humidity environments, H contained in water adhering to glass... ＋ Li ＋ It is prone to leaching. Therefore, the adhesion between glass and resin tends to decrease, making it difficult to maintain sufficient strength as a glass fiber composite resin. In addition, there is a risk that raw material costs will rise due to concerns about the supply of raw materials. Therefore, Li ２ It is preferable to keep the O content as low as possible. Therefore, Li ２ The upper limit of the O content is preferably 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, or 0.05% or less, and is particularly preferably less than 0.05%.

[0039] (Na ２ O) Na ２ O is a component that reduces the viscosity of glass. However, because the difference in electronegativity between sodium atoms and oxygen atoms is large and polarization is easily achieved, it is a component that easily increases the dielectric constant ε and dielectric loss tangent tanδ of glass. In addition, in high temperature and high humidity environments, H contained in water adhering to glass... ＋ Na ＋ It is prone to leaching. Therefore, the adhesion between the glass and the resin is likely to decrease, making it difficult to maintain sufficient strength as a glass fiber composite resin. Hence, Na ２ It is preferable to keep the O content as low as possible. Therefore, Na ２ The upper limit of the O content is preferably 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, and 0.05% or less, with less than 0.05% being particularly preferred. On the other hand, Na ２ O is present as an impurity in the glass raw material, and Na is derived from the above raw material. ２ Completely removing oxygen may increase manufacturing costs. Therefore, Na is used within a range that does not affect the dielectric constant ε or dielectric loss tangent tanδ of the glass. ２It may contain oxygen. For example, Na ２ The content of O may be 0.001% or more, 0.002% or more, or 0.003% or more.

[0040] (K ２ O) K ２ O is a component that reduces the viscosity of glass. However, because the difference in electronegativity between potassium atoms and oxygen atoms is large and polarization is easily achieved, it is a component that easily increases the dielectric constant ε and dielectric loss tangent tanδ of glass. In addition, under high temperature and high humidity conditions, H contained in water adhering to glass... ＋ K ＋ It is prone to leaching. Therefore, the adhesion between the glass and the resin is likely to decrease, making it difficult to maintain sufficient strength as a glass fiber composite resin. Hence, K ２ It is preferable to keep the O content as low as possible. Therefore, K ２ The upper limit of the O content is preferably 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, and 0.05% or less, and is particularly preferably less than 0.05%. On the other hand, K ２ O is present as an impurity in the glass raw material, and K is derived from the above raw material. ２ Completely removing oxygen may increase manufacturing costs. Therefore, K is used within a range that does not affect the dielectric constant ε or dielectric loss tangent tanδ of the glass. ２ It may contain O. For example, K ２ The content of O may be 0.001% or more, 0.002% or more, or 0.003% or more.

[0041] (Li ２ O + Na ２ O+K ２ O) Li ２ O, Na ２ O and K ２ Alkali metal components such as oxygen tend to increase the dielectric constant ε and dielectric loss tangent tanδ of glass. Furthermore, there is a risk of causing glass erosion due to alkali leaching. Therefore, the combined amount of these components Li ２ O + Na ２ O+K ２It is preferable to minimize the amount of O. Therefore, Li ２ O + Na ２ O+K ２ The upper limit of O is preferably 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, and 0.07% or less, and particularly preferably 0.06% or less. On the other hand, alkali metal components are contained as impurities in the glass raw materials, and if alkali metal components are completely removed from the above raw materials, the manufacturing cost may increase. Therefore, alkali metal components may be included in a range that does not affect the dielectric constant ε and dielectric loss tangent tanδ of the glass. For example, Li ２ O + Na ２ O+K ２ O may be 0.001% or more, 0.002% or more, or 0.005% or more.

[0042] (Na ２ O / (Li ２ O + Na ２ O+K ２ O)) Also, Li ２ O, Na ２ O and K ２ In the alkali metal components of O, the movement of alkali components can be suppressed by allowing each component to coexist, thereby reducing the dielectric constant ε and dielectric loss tangent tanδ. Among the alkali metal components, Na in particular ２ O has electronegativity and ionic radius Li ２ O, Na ２ O, K ２ It is intermediate among O atoms and is effective in suppressing the movement of alkaline components. Therefore, in terms of mass ratio, Na ２ O / (Li ２ O + Na ２ O+K ２ By adjusting the value of O) to an appropriate range, the influence on the dielectric constant ε and dielectric loss tangent tanδ of the glass can be suppressed. Therefore, in terms of mass ratio, Na ２ O / (Li ２ O + Na ２ O+K ２The upper limit of the value of O) is preferably 1 or less, 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, and 0.94 or less, and particularly preferably 0.93 or less. On the other hand, Na ２ O / (Li ２ O + Na ２ O+K ２ If the value of O) is too small, manufacturing costs may increase. Therefore, in terms of mass ratio, Na ２ O / (Li ２ O + Na ２ O+K ２ The lower limit of the value of O) is preferably 0.001 or higher, 0.002 or higher, 0.003 or higher, 0.005 or higher, 0.01 or higher, 0.05 or higher, 0.1 or higher, 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.51 or higher, and 0.52 or higher, and particularly preferably 0.53 or higher. ２ O / (Li ２ O + Na ２ O+K ２ O) is Na ２ The amount of O is Li ２ O + Na ２ O+K ２ This refers to the value obtained by dividing by the O content.

[0043] (MgO) MgO is a component that reduces the viscosity of glass. Also, compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. However, Al ２ O ３In glass compositions with a high content of MgO, there is a risk of promoting phase separation and crystal precipitation of the glass. This may lead to a deterioration of the dielectric constant ε and dielectric loss tangent tanδ of the glass, and an increase in the thermal expansion coefficient α. Therefore, it is preferable to keep the MgO content as low as possible. Accordingly, the upper limits of the MgO content are preferably 3% or less, 2.8% or less, 2.5% or less, 2.2% or less, 2% or less, 1.8% or less, 1.6% or less, 1.4% or less, 1.2% or less, 1% or less, 0.8% or less, 0.6% or less, 0.4% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, less than 0.05%, 0.04% or less, less than 0.04%, and 0.03% or less, with less than 0.03% being particularly preferable. On the other hand, MgO can be present as an impurity in glass raw materials, and completely removing MgO from these raw materials may increase manufacturing costs. Therefore, MgO may be included in a range that does not affect the dielectric constant ε and dielectric loss tangent tanδ of the glass. For example, the MgO content may be 0.001% or more, 0.002% or more, 0.003% or more, or 0.004% or more.

[0044] (CaO) CaO is a component that reduces the viscosity of glass. Also, compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. However, Al ２ O ３In glass compositions with a high content of CaO, there is a risk of promoting phase separation and crystal precipitation of the glass. This may lead to a deterioration of the dielectric constant ε and dielectric loss tangent tanδ of the glass, and an increase in the thermal expansion coefficient α. Therefore, it is preferable to keep the CaO content as low as possible. Accordingly, the upper limits of the CaO content are preferably 3% or less, 2.8% or less, 2.5% or less, 2.2% or less, 2% or less, 1.8% or less, 1.6% or less, 1.4% or less, 1.2% or less, 1% or less, 0.8% or less, 0.6% or less, 0.4% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, less than 0.05%, 0.04% or less, less than 0.04%, and 0.03% or less, with less than 0.03% being particularly preferable. On the other hand, CaO can be present as an impurity in glass raw materials, and completely removing CaO from these raw materials may increase manufacturing costs. Therefore, CaO may be included in a range that does not affect the dielectric constant ε and dielectric loss tangent tanδ of the glass. For example, the CaO content may be 0.001% or more, 0.002% or more, 0.003% or more, or 0.004% or more.

[0045] (SrO) SrO is a component that reduces the viscosity of glass. Also, compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. However, Al ２ O ３In glass compositions with a high content of srO, there is a risk of promoting phase separation and crystal precipitation of the glass. This may lead to a deterioration of the dielectric constant ε and dielectric loss tangent tanδ of the glass, and an increase in the thermal expansion coefficient α. Therefore, it is preferable to keep the srO content as low as possible. Accordingly, the upper limits of the srO content are preferably 3% or less, 2.8% or less, 2.5% or less, 2.2% or less, 2% or less, 1.8% or less, 1.6% or less, 1.4% or less, 1.2% or less, 1% or less, 0.8% or less, 0.6% or less, 0.4% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, less than 0.05%, 0.04% or less, less than 0.04%, and 0.03% or less, with less than 0.03% being particularly preferable. On the other hand, SrO can be present as an impurity in glass raw materials, and completely removing SrO from these raw materials may increase manufacturing costs. Therefore, SrO may be included in a range that does not affect the dielectric constant ε and dielectric loss tangent tanδ of the glass. For example, the SrO content may be 0.001% or more, 0.002% or more, 0.003% or more, or 0.004% or more.

[0046] (BaO) BaO is a component that reduces the viscosity of glass. Also, compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. However, Al ２ O ３In glass compositions with a high BaO content, there is a risk of promoting phase separation and crystal precipitation of the glass. This may lead to a deterioration of the dielectric constant ε and dielectric loss tangent tanδ of the glass, and an increase in the thermal expansion coefficient α. Therefore, it is preferable to keep the BaO content as low as possible. Accordingly, the upper limits of the BaO content are preferably 3% or less, 2.8% or less, 2.5% or less, 2.2% or less, 2% or less, 1.8% or less, 1.6% or less, 1.4% or less, 1.2% or less, 1% or less, 0.8% or less, 0.6% or less, 0.4% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, less than 0.05%, 0.04% or less, less than 0.04%, and 0.03% or less, with less than 0.03% being particularly preferable. On the other hand, BaO can be present as an impurity in glass raw materials, and completely removing BaO from the raw materials may increase manufacturing costs. Therefore, BaO may be included in a range that does not affect the dielectric constant ε and dielectric loss tangent tanδ of the glass. For example, the BaO content may be 0.001% or more, 0.002% or more, 0.003% or more, or 0.004% or more.

[0047] (ZnO) ZnO is a component that reduces the viscosity of glass. Also, compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. However, Al ２ O ３In glass compositions with a high ZnO content, there is a risk of promoting phase separation and crystal precipitation of the glass. This may lead to a deterioration of the dielectric constant ε and dielectric loss tangent tanδ of the glass, and an increase in the thermal expansion coefficient α. Therefore, it is preferable to keep the ZnO content as low as possible. Accordingly, the upper limits of the ZnO content are preferably 3% or less, 2.8% or less, 2.5% or less, 2.2% or less, 2% or less, 1.8% or less, 1.6% or less, 1.4% or less, 1.2% or less, 1% or less, 0.8% or less, 0.6% or less, 0.4% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, less than 0.05%, 0.04% or less, less than 0.04%, and 0.03% or less, with less than 0.03% being particularly preferable. On the other hand, ZnO can be present as an impurity in glass raw materials, and completely removing ZnO from the raw materials may increase manufacturing costs. Therefore, ZnO may be included in a range that does not affect the dielectric constant ε and dielectric loss tangent tanδ of the glass. For example, the ZnO content may be 0.001% or more, 0.002% or more, 0.003% or more, or 0.004% or more.

[0048] (Li ２ O + Na ２ O+K ２ Alkali metal components, alkaline earth metal components such as MgO, CaO, SrO, and BaO, and ZnO are components that reduce the viscosity of glass. However, if present in large quantities, they may worsen the dielectric constant ε and dielectric loss tangent tanδ of the glass, and increase the thermal expansion coefficient α. Therefore, the total amount of these components Li ２ O + Na ２ O+K ２The upper limit for O + MgO + CaO + SrO + BaO + ZnO is preferably 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.8% or less, 2.5% or less, 2.2% or less, 2% or less, 1.8% or less, 1.6% or less, 1.4% or less, 1.2% or less, 1% or less, 0.8% or less, 0.6% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, less than 0.1%, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, less than 0.05%, 0.04% or less, less than 0.04%, and 0.03% or less, with less than 0.03% being particularly preferred. On the other hand, alkali metal components, alkaline earth metal components, and ZnO can be present as impurities in glass raw materials, and completely removing alkali metal components, alkaline earth metal components, and ZnO from the above raw materials may increase manufacturing costs. Therefore, alkali metal components, alkaline earth metal components, and ZnO may be included in a range that does not affect the dielectric constant ε and dielectric loss tangent tanδ of the glass. For example, Li ２ O + Na ２ O+K ２ The concentration of O + MgO + CaO + SrO + BaO + ZnO may be 0.002% or more, 0.003% or more, or 0.004% or more.

[0049] (TiO ２ , ZrO ２ Fe ２ O ３ MoO ３ , Cr ２ O ３ SO ３ , SnO ２ The glass fiber composition of the present invention is TiO ２ , ZrO ２ Fe ２ O ３ MoO ３ , Cr ２ O ３ SO ３ , SnO ２ It further contains at least one selected from Pt and Rh.

[0050] (TiO ２ ) TiO ２is a component that reduces the viscosity of glass and improves chemical resistance. It is also a component that tends to increase the dielectric constant ε while maintaining the dielectric loss tangent tanδ. However, if the content of TiO ２ is too high, the liquidus temperature Ty of the glass will increase, and devitrification may occur during spinning, which may reduce the production efficiency. The liquidus temperature Ty means the temperature at which crystals precipitate in the glass. Therefore, the upper limit of the content of TiO ２ is preferably 4.5% or less, 4% or less, 3% or less, less than 2%, 1.5% or less, 1% or less, 0.5% or less, less than 0.5%, 0.45% or less, 0.4% or less, 0.35% or less, 0.3% or less, 0.25% or less, 0.2% or less, 0.15% or less, 0.1% or less, 0.08% or less, 0.06% or less, 0.05% or less, and particularly preferably less than 0.05%. On the other hand, TiO ２ is often contained as an impurity in natural raw materials, and when using high-purity raw materials, the manufacturing cost may increase. Therefore, the content of TiO ２ may be 0%, but it may also be contained within a range that does not affect the liquidus temperature Ty of the glass. For example, the content of TiO ２ may be 0.001% or more, 0.005% or more, 0.01% or more.

[0051] (ZrO ２ ) ZrO ２ is a component that can be mixed in from the refractory provided in the glass melting tank. By using a refractory sprayed with Pt or the like as the material of the glass melting tank, the mixing of ZrO ２ can be suppressed, but the manufacturing cost may increase. Therefore, the content of ZrO ２ may be 0%, but it may also be contained within a range that does not affect the properties of the glass. Also, if the content is small, the effect of suppressing crystal precipitation can be expected. Therefore, the content of ZrO ２ may be 0.001% or more, 0.005% or more, 0.01% or more, 0.05% or more, 0.08% or more, 0.1% or more. On the other hand, if the content of ZrO ２ is too high, the viscosity of the glass will increase and the phase separation of the glass will be easily promoted. Therefore, ZrO ２The upper limit of the content is preferably 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, and particularly preferably 1% or less.

[0052] (Fe ２ O ３ ) Fe ２ O ３ is a component that increases the dielectric constant ε and dielectric loss tangent tanδ of the glass. Therefore, the content of Fe ２ O ３ is preferably minimized. Therefore, the upper limit of the content of Fe ２ O ３ is preferably 0.1% or less, 0.09% or less, and particularly preferably 0.08% or less. On the other hand, Fe ２ O ３ is a component that can be mixed in from natural raw materials or melting equipment. Using high-purity raw materials or expensive melting equipment may increase production costs. Therefore, the content of Fe ２ O ３ may be 0%, but it may also be contained within a range that does not affect the dielectric constant ε and dielectric loss tangent tanδ of the glass. For example, the content of Fe ２ O ３ may be 0.0001% or more, 0.0005% or more, 0.001% or more, 0.005% or more, 0.01% or more.

[0053] (MoO ３ ) MoO ３ is a component that promotes phase separation of the glass and promotes a decrease in chemical resistance and crystal formation. Therefore, the content of MoO ３ is preferably minimized. Therefore, the upper limit of the content of MoO ３ is preferably 0.1% or less, 0.09% or less, 0.07% or less, 0.05% or less, 0.03% or less, 0.02% or less, 0.01% or less, less than 0.01%, 0.005% or less, less than 0.005%, 0.001% or less, and particularly preferably less than 0.001%.

[0054] By the way, when melting a glass containing a large amount of B ２ O ３ at a high temperature, B is released from the surface of the glass raw material batch or glass melt charged into the glass melting tank. ２O ３ It may evaporate. B ２ O ３ When the molten glass evaporates, a difference in composition occurs between the surface and the interior of the molten glass, making it difficult to obtain glass with the designed composition. Therefore, to suppress excessive heating of the surface of the molten glass, electromelting, which involves heating the molten glass with an electric current using electrodes, is also an effective means of melting glass. As an electrode material in electromelting, MoO is generally used. ３ Electrodes such as Pt electrodes and Sn electrodes are used, but MoO ３ When electromelting is performed using electrodes, MoO ３ Contamination may occur. Therefore, MoO ３ The content may be 0%, but it may also be 1 ppb or more, 10 ppb or more, 50 ppb or more, 100 ppb or more, 200 ppb or more, or 300 ppb or more.

[0055] (Cr ２ O ３ ) Cr ２ O ３ It is a component that easily colors glass and affects the color tone of glass fiber composite resin, which is a composite of glass and resin. Therefore, Cr ２ O ３ It is preferable to keep the content of as little as possible. Therefore, Cr ２ O ３ The upper limit of the content is preferably 0.1% or less, 0.09% or less, 0.08% or less, 0.07% or less, 0.06% or less, 0.05% or less, 0.04% or less, 0.03% or less, 0.02% or less, and less than 0.02%, with a particularly preferred limit of 0.01% or less. On the other hand, Cr ２ O ３ This is a component that can be mixed in from the refractory material provided in the glass melting tank. By using refractory material with Pt or the like as the material for the glass melting tank, Cr ２ O ３ While it is possible to suppress contamination, there is a risk that manufacturing costs will increase. Therefore, Cr ２ O ３ The content may be 0%, but it may be included in a range that does not affect the color tone of the glass. For example, Cr ２ O ３The content may be 0.0001% or more, or 0.0005% or more.

[0056] (SO ３ ) SO ３ SO4 is produced in a glass melt at temperatures above 1400°C. ３ It is a component that releases gas, resulting in a clarifying effect. SO ３ The lower limit of the content is not particularly limited, but to obtain a sufficient clarifying effect, it can be 0.0001% or more, 0.0005% or more, 0.001% or more, or 0.005% or more. On the other hand, SO ３ If the content is too high, the glass melt becomes more easily reduced, and during spinning, alloys may be formed between the noble metal elements in the fiber-making equipment such as bushings and the metal elements in the glass, which can easily corrode the fiber-making equipment. Also, when the melting equipment and the glass come into contact, SO ３ The solubility of the gas changes, making it easier for revoile bubbles to form at the interface between the melting equipment and the glass. These bubbles can become mixed into the fibers, potentially causing yarn breakage and reducing productivity. Therefore, SO ３ The upper limit of the content is preferably 0.1% or less, preferably 0.05% or less, and particularly preferably 0.01% or less.

[0057] (SnO ２ ) SnO ２ SnO is a component that releases oxygen gas in glass melts above 1500°C due to changes in the valence of Sn in response to temperature changes in the glass melt, resulting in a clarifying effect. ２ Because it releases gas at a high temperature, it can be used as a clarifying agent in glass where the content of alkali metal components and alkaline earth metal components in the glass is low, and the viscosity of the glass melt tends to be high. ２ The lower limit of the content may be 0%, but to obtain a sufficient clarifying effect, it can be set to 0.0001% or more, 0.0005% or more, 0.001% or more, or 0.005% or more. On the other hand, SnO ２ If the content is too high, it can easily cause discoloration of the glass and precipitation of crystals within the glass. Therefore, SnO ２The upper limit of the content is preferably 0.5% or less, 0.45% or less, 0.4% or less, 0.35% or less, and particularly preferably 0.3% or less.

[0058] (Pt) Pt is a component that promotes the formation of phase separation and crystals in glass. Therefore, it is preferable to keep the Pt content as low as possible. Accordingly, the upper limit of the Pt content is preferably 0.1% or less, 0.09% or less, 0.07% or less, 0.05% or less, 0.03% or less, 0.01% or less, 0.005% or less, less than 0.005%, and 0.001% or less, and is particularly preferably less than 0.001%. On the other hand, the Pt content may be 0%, but since it is a component that can be mixed in from melting equipment such as glass melting tanks, it may be included in a range that does not affect the phase separation and crystal formation of glass. For example, the Pt content may be 1 ppb or more, 10 ppb or more, 50 ppb or more, 100 ppb or more, 200 ppb or more, and 300 ppb or more.

[0059] (Rh) Rh is a component that easily colors glass and affects the color tone of glass fiber composite resin, which is a composite of glass and resin. Therefore, it is preferable to keep the Rh content as low as possible. Accordingly, the upper limit of the Rh content is preferably 0.1% or less, 0.09% or less, 0.07% or less, 0.05% or less, 0.03% or less, 0.01% or less, 0.005% or less, and less than 0.005%, and particularly preferably 0.001% or less. On the other hand, the Rh content may be 0%, but since it is a component that can be mixed in from melting equipment such as glass melting tanks, it may be included in a range that does not affect the color tone of the glass. For example, the Rh content may be 1 ppb or more, 10 ppb or more, 50 ppb or more, 100 ppb or more, 200 ppb or more, or 300 ppb or more.

[0060] (Other ingredients) In addition, Cl is added for the purpose of improving the clarity or reducing the viscosity of the glass melt. ２ F ２ Sb ２ O ３ As ２ O ３ , CEO ２Any one or more of the following may be included. From the viewpoint of preventing the generation of reboil foam, reducing environmental impact, and suppressing equipment corrosion, the upper limits of the respective contents are preferably 0.8% or less, 0.6% or less, 0.5% or less, 0.3% or less, 0.2% or less, 0.1% or less, 0.05% or less, and 0.03% or less, with a particularly preferred limit of 0.01% or less.

[0061] The following describes glass fiber compositions according to the first to third embodiments of the present invention.

[0062] [First Embodiment] Below are composition 1-1, which is a preferred composition of the glass fiber composition according to the first embodiment of the present invention, and composition example 1-2, which is a more preferred composition example.

[0063] [Composition 1-1] The glass composition is SiO2 by mass%. ２ 40-63% Al ２ O ３ 10-35% B ２ O ３ 5-30% P ２ O ５ 0-12% SnO ２ 0-0.3% Li ２ O + Na ２ O+K ２ It contains 0-0.1% of O + MgO + CaO + SrO + BaO + ZnO, and TiO ２ , ZrO ２ Fe ２ O ３ MoO ３ , Cr ２ O ３ SO ３ , SnO ２ A glass fiber composition characterized by further containing at least one selected from Pt and Rh.

[0064] [Composition 1-2] The glass composition is SiO2 by mass%. ２ 47-57% Al ２ O ３ 14-25% B ２ O ３ 15-25% P ２ O ５ 6-12% SnO２ 0.0001~0.3% Li ２ O + Na ２ O+K ２ A glass fiber composition characterized by containing 0 to 0.1% of O + MgO + CaO + SrO + BaO + ZnO.

[0065] The glass fiber composition according to the first embodiment has a low dielectric constant and a low dielectric loss tangent, as well as a low coefficient of thermal expansion. The reasons for specifying the content range of each component are as described above, and therefore no further explanation is provided.

[0066] [Second Embodiment] The following describes a glass fiber composition according to a second embodiment of the present invention. Below are composition 2-1, which is a preferred composition example of the glass fiber composition according to the second embodiment of the present invention, and composition 2-2, which is a more preferred composition example.

[0067] [Composition 2-1] The glass composition is SiO2 by mass%. ２ 45-57% Al ２ O ３ 16-30% B ２ O ３ 15-20.5% P ２ O ５ 1-11.5% SnO ２ 0.0001~0.5% Li ２ O + Na ２ O+K ２ A glass fiber composition characterized by containing 1 to 3.7% of O + MgO + CaO + SrO + BaO + ZnO.

[0068] [Composition 2-2] The glass composition is SiO2 by mass%. ２ 49-54% Al ２ O ３ 18-23% B ２ O ３ 17-20.3% P ２ O ５ 5-10% SnO ２ 0.0001~0.3% Li ２ O + Na ２ O+K ２A glass fiber composition characterized by containing 1.4 to 3% of O + MgO + CaO + SrO + BaO + ZnO.

[0069] A glass fiber composition according to the second embodiment, Li ２ O + Na ２ O+K ２ The inclusion of 1% or more of O + MgO + CaO + SrO + BaO + ZnO results in superior productivity during glass fiber molding. The reasons for specifying the content range for each component are explained below.

[0070] (SiO ２ ) SiO ２ It is a component that forms the mesh-like skeletal structure of glass. It is also a component that reduces the dielectric constant ε and dielectric loss tangent tanδ of glass. SiO ２ If the content is too low, it becomes difficult to obtain the effect of lowering the dielectric constant ε and dielectric loss tangent tanδ. Therefore, SiO ２ The lower limit of the content is preferably 45% or more, 46% or more, 47% or more, or 48% or more, and particularly preferably 49% or more. On the other hand, SiO ２ If the content of SiO is too high, the solubility of the raw material decreases, making it difficult to obtain homogeneous glass. In addition, the spinning temperature Tx increases, reducing productivity. Furthermore, in order to improve productivity, it is necessary to add components to improve melting, and these components tend to increase the dielectric constant ε and dielectric loss tangent tanδ. Therefore, SiO ２ The upper limit of the content is preferably 57% or less, 56% or less, 55% or less, or 54% or less, and particularly preferably 53% or less.

[0071] (Al ２ O ３ ) Al ２ O ３ is either alone or P ２ O ５ Ya B ２ O ３ It is also a component that forms the network-like skeletal structure of glass. Furthermore, it suppresses the phase separation of glass, and SiO ２ -B ２ O ３ -P ２ O ５In the glass system, it is a component that lowers the high-temperature viscosity. Furthermore, it is also a component that increases the Young's modulus. From the viewpoint of obtaining the above effects, in this embodiment, Al ２ O ３ The lower limit of the content is preferably 16% or more, 16.5% or more, 17% or more, 17.5% or more, and especially 18% or more. On the other hand, Al ２ O ３ If the content is too high, the difference in electronegativity between aluminum atoms and oxygen atoms becomes large, which tends to increase the dielectric constant ε and dielectric loss tangent tanδ. Therefore, Al ２ O ３ The upper limit of the content is preferably 30% or less, 28% or less, 26% or less, or 24% or less, and particularly preferably 22% or less.

[0072] (B ２ O ３ ) B ２ O ３ SiO ２ Similarly, it is a component that forms the mesh-like skeletal structure of glass. It is also a component that reduces the dielectric constant ε and dielectric loss tangent tanδ of glass. B ２ O ３ If the content is too low, it becomes difficult to obtain the effect of lowering the dielectric constant ε and dielectric loss tangent tanδ of the glass. Therefore, B ２ O ３ The lower limit of the content is preferably 15% or more, 15.5% or more, 16% or more, and 16.5% or more, and particularly preferably 17% or more. On the other hand, B ２ O ３ If the content is too high, the glass may become more prone to phase separation. Also, B on the surface ２ O ３ The formation of a rich phase can make the surface more prone to cracking, potentially making stable spinning difficult. Therefore, B ２ O ３ The upper limit of the content is preferably 20.5% or less, 20.4% or less, 20.3% or less, and 20.2% or less, and particularly preferably 20.1% or less.

[0073] (P ２ O ５ ) P ２ O ５ Al ２ O３ Ya B ２ O ５ It is also a component that forms the mesh-like skeletal structure of glass. Furthermore, because the difference in electronegativity between phosphorus atoms and oxygen atoms is small, it is a component that lowers the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of obtaining the above effects, P ２ O ５ The lower limit is preferably 1% or more, 2% or more, 3% or more, or 4% or more, and particularly preferably 5% or more. On the other hand, P ２ O ５ If the content is too high, raw material costs may increase. Also, chemical resistance is easily reduced, and there is a risk of glass fiber erosion during chemical treatment such as Cu foil etching. Therefore, P ２ O ５ The upper limit of the content is preferably 11.5% or less, 11% or less, 10.5% or less, or 10% or less, and particularly preferably 9.9% or less.

[0074] (SiO ２ +B ２ O ３ ) SiO ２ and B ２ O ３ These are all components that reduce the dielectric constant ε and dielectric loss tangent tanδ of glass. The total amount of these components is SiO ２ +B ２ O ３ If the amount is too small, it becomes difficult to obtain the effect of lowering the dielectric constant ε and dielectric loss tangent tanδ of the glass. Also, the spinning temperature Tx will increase, which may increase production costs. Therefore, SiO ２ +B ２ O ３ The lower limit is preferably 60% or more, 61% or more, 62% or more, or 63% or more, and particularly preferably 64% or more. On the other hand, SiO ２ +B ２ O ３ If there is too much of it, the glass will split into phases, and its chemical resistance will easily decrease. Therefore, SiO ２ +B ２ O ３ The upper limit is preferably 75% or less, 74% or less, 73% or less, or 72% or less, and particularly preferably 71% or less.

[0075] (B２ O ３ / (B ２ O ３ +P ２ O ５ )) B ２ O ３ P ２ O ５ In the contained glass, a three-coordinate planar structure may be formed. B ２ O ３ If the content is too low, the dielectric constant ε and dielectric loss tangent tanδ of the glass tend to become high. Therefore, B calculated in mole percent ２ O ３ and P ２ O ５ B relative to the total amount ２ O ３ Content ratio B ２ O ３ / (B ２ O ３ +P ２ O ５ The lower limit of the value of ) is preferably 0.5 or higher, 0.6 or higher, 0.65 or higher, or 0.7 or higher, and particularly preferably 0.75 or higher. On the other hand, SiO ２ Because it forms a four-coordinate tetrahedron structure, SiO ２ It has as its main component and P ２ O ５ In glass containing B ２ O ３ If the content is too high, it can lead to uneven structure, making the glass more prone to phase separation. Therefore, B ２ O ３ / (B ２ O ３ +P ２ O ５ If the value of ) is too large, there is a risk that the glass will be more prone to phase separation. Therefore, B ２ O ３ / (B ２ O ３ +P ２ O ５ The upper limit of the value of ) is preferably 0.92 or less, 0.91 or less, 0.90 or less, or 0.88 or less, and particularly preferably 0.87 or less.

[0076] (MgO) MgO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the MgO content is preferably 0% or more, 0.2% or more, 0.4% or more, or 0.6% or more, and particularly preferably 0.8% or more. On the other hand, if the MgO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the MgO content is preferably 3% or less, 2.8% or less, 2.6% or less, or 2.4% or less, and particularly preferably 2.3% or less.

[0077] (CaO) CaO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the CaO content is preferably 0% or more, 0.2% or more, 0.4% or more, or 0.6% or more, and particularly preferably 0.8% or more. On the other hand, if the CaO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the CaO content is preferably 3% or less, 2.5% or less, 2% or less, or 1.8% or less, and particularly preferably 1.7% or less.

[0078] (SrO) SrO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the SrO content is preferably 0% or more, 0.2% or more, 0.4% or more, or 0.6% or more, and particularly preferably 0.8% or more. On the other hand, if the SrO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the SrO content is preferably 3.7% or less, 3.5% or less, 3.3% or less, or 3.1% or less, and particularly preferably 3% or less.

[0079] (BaO) BaO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the BaO content is preferably 0% or more, 0.2% or more, 0.4% or more, and 0.6% or more, and particularly preferably 0.8% or more. On the other hand, if the BaO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the BaO content is preferably 3% or less, 2.8% or less, 2.6% or less, and 2.4% or less, and particularly preferably 2.2% or less.

[0080] (ZnO) ZnO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the ZnO content is preferably 0% or more, 0.2% or more, 0.4% or more, or 0.6% or more, and particularly preferably 0.8% or more. On the other hand, if the ZnO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the ZnO content is preferably 3% or less, 2.8% or less, 2.6% or less, or 2.4% or less, and particularly preferably 2.3% or less.

[0081] (Li ２ O + Na ２ O+K ２ (O + MgO + CaO + SrO + BaO + ZnO) Alkali metal components, alkaline earth metal components such as MgO, CaO, SrO, BaO, and ZnO are components that reduce the viscosity of glass. From the viewpoint of improving productivity during glass fiber molding, the total amount of these Li ２ O + Na ２ O+K ２ The lower limit of O + MgO + CaO + SrO + BaO + ZnO is preferably 1% or more, 1.2% or more, 1.4% or more, and 1.6% or more, and particularly preferably 1.8% or more. On the other hand, Li ２ O + Na ２ O+K ２If there is too much O + MgO + CaO + SrO + BaO + ZnO, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ, and an increase in the thermal expansion coefficient α. Therefore, Li ２ O + Na ２ O+K ２ The upper limit of O + MgO + CaO + SrO + BaO + ZnO is preferably 3.7% or less, 3% or less, 2.9% or less, or 2.8% or less, and particularly preferably 2.7% or less.

[0082] Li ２ O, Na ２ O, K ２ O, Li ２ O + Na ２ O+K ２ O, Na ２ O / (Li ２ O + Na ２ O+K ２ O), TiO ２ , ZrO ２ Fe ２ O ３ MoO ３ , Cr ２ O ３ SO ３ , SnO ２ As for Pt, Rh, and other components, they are the same as in the first embodiment, so their explanation is omitted.

[0083] [Third Embodiment] The following describes a glass fiber composition according to the third embodiment of the present invention. Below are composition 3-1, which is a preferred composition example of the glass fiber composition according to the third embodiment of the present invention, and composition example 3-2, which is a more preferred composition example.

[0084] [Composition 3-1] The glass composition is SiO2 by mass%. ２ 53-63% Al ２ O ３ 5-15% B ２ O ３ More than 20.5 ~ 31% P ２ O ５ 0-5% TiO ２ 0-5% Li ２ O + Na ２ O+K ２A glass fiber composition characterized by containing 1 to 5.1% of O + MgO + CaO + SrO + BaO + ZnO.

[0085] [Composition 3-2] As a glass composition, in mass%, SiO ２ 54 to 62% Al ２ O ３ 7 to 15% B ２ O ３ 21 to 31% P ２ O ５ 0.5 to 5% TiO ２ 0 to 4.6% Li ２ O 0 to less than 0.05% Li ２ O + Na ２ O + K ２ O 0 to 0.1% Fe ２ O ３ 0 to 0.1% Li ２ O + Na ２ O + K ２ A glass fiber composition characterized by containing 1 to 3.2% of O + MgO + CaO + SrO + BaO + ZnO.

[0086] The glass fiber composition according to the third embodiment has Al ２ O ３ at 15% or less, Li ２ O + Na ２ O + K ２ O + MgO + CaO + SrO + BaO + ZnO at 1% or more, and B ２ O ３ contained in an amount exceeding 20.5%, thereby achieving both low dielectric constant and low dielectric tangent, having a low coefficient of thermal expansion, and being excellent in productivity during glass fiber forming. The reasons for determining the content ranges of each component are described below.

[0087] (SiO ２ ) SiO ２ is a component that forms the network-like skeletal structure of the glass. It is also a component that reduces the dielectric constant ε and dielectric tangent tanδ of the glass. If the content of SiO ２ is too small, it becomes difficult to obtain the effect of reducing the dielectric constant ε and dielectric tangent tanδ. Therefore, SiO ２The lower limit of the content is preferably 53% or more, 53.5% or more, 54% or more, and 54.5% or more, and particularly preferably 55% or more. On the other hand, SiO ２ If the content of SiO is too high, the solubility of the raw material decreases, making it difficult to obtain homogeneous glass. In addition, the spinning temperature Tx increases, reducing productivity. Furthermore, in order to improve productivity, it is necessary to add components to improve melting, and these components tend to increase the dielectric constant ε and dielectric loss tangent tanδ. Therefore, SiO ２ The upper limit of the content is preferably 63% or less, 62% or less, 61% or less, or 60% or less, and particularly preferably 59% or less.

[0088] (Al ２ O ３ ) Al ２ O ３ is either alone or P ２ O ５ Ya B ２ O ３ It is also a component that forms the network-like skeletal structure of glass. Furthermore, it suppresses the phase separation of glass, and SiO ２ -B ２ O ３ -P ２ O ５ It is a component that reduces high-temperature viscosity in glass systems. From the viewpoint of obtaining the above effect, Al ２ O ３ The lower limit of the content is preferably 5% or more, 6% or more, 7% or more, or 8% or more, and particularly preferably 8.5% or more. On the other hand, Al ２ O ３ If the content is too high, the difference in electronegativity between aluminum atoms and oxygen atoms becomes large, which tends to increase the dielectric constant ε and dielectric loss tangent tanδ. Therefore, Al ２ O ３ The upper limit of the content is preferably 15% or less, 14% or less, 13% or less, or 12.5% ​​or less, and particularly preferably 12% or less.

[0089] (B ２ O ３ ) B ２ O ３ SiO ２Similarly, it is a component that forms the mesh-like skeletal structure of glass. It is also a component that reduces the dielectric constant ε and dielectric loss tangent tanδ of glass. B ２ O ３ If the content is too low, it becomes difficult to obtain the effect of lowering the dielectric constant ε and dielectric loss tangent tanδ of the glass. Therefore, B ２ O ３ The lower limit of the content is preferably more than 20.5%, 21% or more, 21.5% or more, and 22% or more, and particularly preferably 22.5% or more. On the other hand, B ２ O ３ If the content is too high, the glass may become more prone to phase separation. Also, B on the surface ２ O ３ The formation of a rich phase can easily lead to crack formation on the surface, potentially making stable spinning difficult. Therefore, B ２ O ３ The upper limit of the content is preferably 31% or less, 30% or less, 29% or less, or 28% or less, and particularly preferably 27% or less.

[0090] (P ２ O ５ ) P ２ O ５ Al ２ O ３ Ya B ２ O ５ It is also a component that forms the mesh-like skeletal structure of glass. Furthermore, because the difference in electronegativity between phosphorus and oxygen atoms is small, it is a component that reduces the dielectric constant ε and dielectric loss tangent tanδ of glass. P ２ O ５ The content may be 0%, but from the viewpoint of obtaining the above effects, it is preferable to have 0.5% or more, 1% or more, or 1.2% or more, and particularly preferable to have 1.4% or more. On the other hand, P ２ O ５ If the content is too high, raw material costs may increase. Also, chemical resistance is easily reduced, and there is a risk of glass fiber erosion during chemical treatment such as Cu foil etching. Therefore, P ２ O ５ The upper limit of the content is preferably 5% or less, 4.5% or less, 4% or less, or 3.5% or less, and particularly preferably 3% or less.

[0091] (SiO ２ +B ２ O ３ ) SiO ２ and B ２ O ３ These are all components that reduce the dielectric constant ε and dielectric loss tangent tanδ of glass. SiO ２ +B ２ O ３ If the content is too low, it becomes difficult to obtain the effect of lowering the dielectric constant ε and dielectric loss tangent tanδ of the glass. Also, the spinning temperature Tx will increase, which may increase production costs. Therefore, SiO ２ +B ２ O ３ The lower limit of the allowable amount is preferably 73.5% or more, 75% or more, 77% or more, and 78% or more, and particularly preferably 79% or more. On the other hand, SiO ２ +B ２ O ３ If the content is too high, the glass will undergo phase separation, and its chemical resistance will easily decrease. Therefore, SiO ２ +B ２ O ３ The upper limit of the content is preferably 94% or less, 92% or less, 90% or less, or 89% or less, and particularly preferably 88% or less.

[0092] (B ２ O ３ / (B ２ O ３ +P ２ O ５ )) B ２ O ３ P ２ O ５ In the contained glass, a three-coordinate planar structure may be formed. B ２ O ３ If the content is too low, the dielectric constant ε and dielectric loss tangent tanδ of the glass tend to become high. Therefore, B calculated in mole percent ２ O ３ and P ２ O ５ B relative to the total amount ２ O ３ Content ratio B ２ O ３ / (B ２ O ３ +P ２O ５ The lower limit of the value of ) is preferably 0.9 or higher, 0.91 or higher, 0.92 or higher, or 0.93 or higher, and particularly preferably 0.94 or higher. On the other hand, SiO ２ Because it forms a four-coordinate tetrahedron structure, SiO ２ It has as its main component and P ２ O ５ In glass containing B ２ O ３ If the content is too high, it can lead to uneven structure, making the glass more prone to phase separation. Therefore, B ２ O ３ / (B ２ O ３ +P ２ O ５ If the value of ) is too large, there is a risk that the glass will be more prone to phase separation. Therefore, B ２ O ３ / (B ２ O ３ +P ２ O ５ The upper limit of the value of ) is preferably 0.999 or less, 0.998 or less, 0.995 or less, or 0.993 or less, and is particularly preferably 0.99 or less.

[0093] (MgO) MgO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the MgO content is preferably 0% or more, 0.1% or more, 0.2% or more, or 0.3% or more, and particularly preferably 0.4% or more. On the other hand, if the MgO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the MgO content is preferably 2% or less, 1.7% or less, 1.5% or less, or 1.2% or less, and particularly preferably 1.1% or less.

[0094] (CaO) CaO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the CaO content is preferably 0% or more, greater than 0%, 0.1% or more, or 0.2% or more, and particularly preferably greater than 0.2%. On the other hand, if the CaO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the CaO content is preferably 3.5% or less, 3% or less, 2.5% or less, or 2.3% or less, and particularly preferably 2.2% or less.

[0095] (SrO) SrO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the SrO content is preferably 0% or more, 0.1% or more, 0.2% or more, or 0.3% or more, and particularly preferably 0.4% or more. On the other hand, if the SrO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the SrO content is preferably 2% or less, 1.5% or less, 1% or less, or 0.8% or less, and particularly preferably 0.6% or less.

[0096] (BaO) BaO is a component that reduces the viscosity of glass. Compared to alkali metal components, it is a component that does not easily increase the dielectric constant ε and dielectric loss tangent tanδ of glass. From the viewpoint of improving productivity during glass fiber molding, the lower limit of the BaO content is preferably 0% or more, 0.1% or more, 0.2% or more, or 0.3% or more, and particularly preferably 0.4% or more. On the other hand, if the BaO content is too high, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ and an increase in the thermal expansion coefficient α. Therefore, the upper limit of the BaO content is preferably 2% or less, 1.8% or less, 1.7% or less, or 1.6% or less, and particularly preferably 1.5% or less.

[0097] (Li ２ O + Na ２ O+K ２Al (O + MgO + CaO + SrO + BaO + ZnO) Alkali metal components, alkaline earth metal components such as MgO, CaO, SrO, and BaO, and ZnO are components that reduce the viscosity of glass. ２ O ３ When the content of these components is small (for example, 15% or less), even if these components are included, it is difficult to promote the phase separation and crystal precipitation of the glass. From the viewpoint of improving productivity during glass fiber molding, the total amount of these components Li ２ O + Na ２ O+K ２ The lower limit of O + MgO + CaO + SrO + BaO + ZnO is preferably 1% or more, 1.1% or more, 1.2% or more, and 1.3% or more, and particularly preferably 1.4% or more. On the other hand, Li ２ O + Na ２ O+K ２ If there is too much O + MgO + CaO + SrO + BaO + ZnO, it may cause deterioration of the dielectric constant ε and dielectric loss tangent tanδ, and an increase in the thermal expansion coefficient α. Therefore, Li ２ O + Na ２ O+K ２ The upper limit of O + MgO + CaO + SrO + BaO + ZnO is preferably 4% or less, 3.2% or less, 2.5% or less, or 2% or less, and particularly preferably 1.8% or less.

[0098] (TiO ２ ) TiO ２ This component reduces the viscosity of glass and improves its chemical resistance. It also easily increases the dielectric constant ε while maintaining the dielectric loss tangent tanδ. (TiO) ２ The content may be 0%, but from the viewpoint of improving productivity during glass fiber molding, it is preferable to have 1% or more, 2% or more, or 3% or more, and particularly preferable to have 3.5% or more. On the other hand, TiO ２ If the content of TiO is too high, the liquidus temperature Ty of the glass will rise, which may cause devitrification during spinning and reduce production efficiency. Note that the liquidus temperature Ty refers to the temperature at which crystals precipitate in the glass. Therefore, TiO ２ The upper limit of the content is preferably 5% or less, 4.8% or less, 4.6% or less, or 4.4% or less, and particularly preferably 4.2% or less.

[0099] Li２ O, Na ２ O, K ２ O, Li ２ O + Na ２ O+K ２ O, Na ２ O / (Li ２ O + Na ２ O+K ２ O), ZnO, ZrO ２ Fe ２ O ３ MoO ３ , Cr ２ O ３ SO ３ , SnO ２ As for Pt, Rh, and other components, they are the same as in the first embodiment, so their explanation is omitted.

[0100] The glass composition described above can be measured, for example, by known X-ray fluorescence analysis.

[0101] The properties of the glass fiber composition of the present invention, glass fibers, and methods for producing glass fibers will be described below.

[0102] The glass fiber composition of the present invention preferably has a dielectric constant ε of 6 or less, 5.5 or less, 5 or less, and particularly 4.7 or less at 25°C and 10 GHz. If the dielectric constant ε is too high, the dielectric loss will be large, and the low dielectric properties required for resin reinforcing materials such as printed circuit boards and communication equipment components will not be met. The lower limit of the dielectric constant ε at 25°C and 10 GHz is not particularly limited, but in reality it is 3.7 or higher.

[0103] The glass fiber composition of the present invention preferably has a dielectric constant ε of 6 or less, 5.5 or less, 5 or less, and particularly 4.7 or less at 25°C and 40GHz. If the dielectric constant ε is too high, the dielectric loss will be large, and the low dielectric properties required for resin reinforcing materials such as printed circuit boards and communication equipment components will not be met. The lower limit of the dielectric constant ε at 25°C and 40GHz is not particularly limited, but in reality it is 3.7 or higher.

[0104] The glass fiber composition of the present invention preferably has a dielectric loss tangent tanδ of 0.008 or less, 0.007 or less, 0.006 or less, 0.005 or less, 0.004 or less, and particularly 0.0035 or less at 25°C and 10 GHz. If the dielectric loss tangent tanδ is too high, the dielectric loss will be large, and the low dielectric properties required for resin reinforcing materials such as printed circuit boards and communication equipment components will not be met. The lower limit of the dielectric loss tangent tanδ at 25°C and 10 GHz is not particularly limited, but in reality it is 0.0001 or higher.

[0105] The glass fiber composition of the present invention preferably has a dielectric loss tangent tanδ of 0.01 or less, 0.009 or less, 0.008 or less, 0.007 or less, 0.006 or less, 0.005 or less, 0.004 or less, and particularly 0.0035 or less at 25°C and 40GHz. If the dielectric loss tangent tanδ is too high, the dielectric loss will be large, and the low dielectric properties required for resin reinforcing materials such as printed circuit boards and communication equipment components will not be met. The lower limit of the dielectric loss tangent tanδ at 25°C and 40GHz is not particularly limited, but in reality it is 0.0001 or more.

[0106] The glass fiber composition of the present invention preferably has a spinning temperature Tx of 1560°C or lower, 1550°C or lower, 1540°C or lower, 1530°C or lower, 1520°C or lower, 1510°C or lower, 1500°C or lower, 1490°C or lower, 1480°C or lower, 1470°C or lower, 1460°C or lower, 1450°C or lower, and particularly 1440°C or lower. If the spinning temperature Tx is too high, the fiberization equipment such as bushings will be severely damaged, increasing the frequency of replacement and raising production costs. In addition, precious metal elements will leach from the fiberization equipment into the glass, causing phase separation of the glass and a decrease in chemical resistance. The lower limit of the spinning temperature Tx is not particularly limited, but in reality it is 1000°C or higher.

[0107] The glass fiber composition of the present invention preferably has a liquidus temperature Ty of 1480°C or lower, 1470°C or lower, 1460°C or lower, 1450°C or lower, 1440°C or lower, 1430°C or lower, 1420°C or lower, 1410°C or lower, and particularly 1400°C or lower. If the liquidus temperature Ty is too high, the temperature difference ΔTxy with the spinning temperature Tx tends to become small, which tends to worsen productivity. The lower limit of the liquidus temperature Ty is not particularly limited, but in reality it is 1000°C or higher.

[0108] The glass fiber composition of the present invention preferably has a temperature difference ΔTxy between the spinning temperature Tx and the liquidus temperature Ty of 20°C or more, 25°C or more, 30°C or more, 35°C or more, 40°C or more, and particularly 45°C or more. If the temperature difference ΔTxy is too small, devitrified substances that cause nozzle clogging of the bushing are more likely to occur during glass fiber molding, thus reducing productivity. There is no particular upper limit to the temperature difference ΔTxy, but in reality it is 430°C or less.

[0109] The glass fiber composition of the present invention preferably has a value of (temperature difference ΔTxy / spinning temperature Tx) × 100 of 0 or more, 0.5 or more, 1 or more, 1.5 or more, 2 or more, 2.5 or more, or 3 or more. If this value is too low, the spinning temperature Tx will increase, and devitrified materials will be more likely to be generated, reducing productivity. The upper limit of the value of (temperature difference ΔTxy / spinning temperature Tx) × 100 is not particularly limited, but it is 30 or less.

[0110] The glass fiber composition of the present invention has a density ρ of 2.5 g / cm³. ３ Below, 2.4g / cm ３ The following is particularly true for 2.36 g / cm³. ３ The following is preferable. If the density ρ is too high, the glass fiber composite resin becomes heavy, making weight reduction difficult, for example, when the number of layers of printed circuit boards increases. Although there is no particular lower limit to the density ρ, in reality it is 2.00 g / cm³. ３ That's all.

[0111] The glass fiber composition of the present invention preferably has a Young's modulus E of 30 GPa or more, 35 GPa or more, 40 GPa or more, 45 GPa or more, and particularly 50 GPa or more. If the Young's modulus E is too low, for example, it becomes difficult to obtain the effect of using it as a reinforcing material in glass fiber composite resins such as printed circuit boards, and the effect of suppressing thermal shrinkage and warping. On the other hand, the glass fiber composition of the present invention preferably has a Young's modulus E of 90 GPa or less, and particularly 85 GPa or less. If the Young's modulus E is too high, for example, the drill bit used to drill holes in glass fiber composite resins such as printed circuit boards becomes easily damaged, and productivity tends to deteriorate.

[0112] The glass fiber composition of the present invention preferably has a weight loss rate of 60% or less, 59% or less, 58% or less, 57% or less, and particularly 56% or less after immersion in a 10% hydrochloric acid solution at 80°C for 90 hours. If the weight loss rate is too high, the glass fibers may be eroded, for example, during etching treatment of glass fiber composite resins such as printed circuit boards. The lower limit of the weight loss rate is not particularly limited, but in reality it is 0.1% or more.

[0113] The glass fiber composition of the present invention preferably has a weight loss rate of 60% or less, 59% or less, 58% or less, 57% or less, and particularly 56% or less after immersion in a 10% by mass sodium hydroxide solution at 80°C for 16 hours. If the weight loss rate is too high, there is a risk that the glass fibers may be eroded during etching treatment of glass fiber composite resins such as printed circuit boards. The lower limit of the weight loss rate is not particularly limited, but in reality it is 0.1% or more.

[0114] The glass fiber composition of the present invention has a thermal expansion coefficient α of 3 × 10 at 50 to 200°C. －７ / ℃ or higher, 5 x 10 －７ / ℃ or higher, 8 x 10 －７ / ℃ or higher, especially 10 x 10 －７ It is preferable that the thermal expansion coefficient α is 40 × 10⁻¹⁰ or higher. If the thermal expansion coefficient α is too low, the difference in thermal expansion between the glass fibers and the resin in the glass fiber composite resin will be large, which may cause damage to the glass fiber composite resin. On the other hand, the glass fiber composition of the present invention has a thermal expansion coefficient α of 40 × 10⁻¹⁰ at 50 to 200°C.－７ / ℃ or below, 39 x 10 －７ / ℃ or below, 38 x 10 －７ / ℃ or below, 37 × 10 －７ / ℃ or below, 36 x 10 －７ / ℃ or lower, especially 35 × 10 －７ It is preferable that the temperature is below / °C. If the coefficient of thermal expansion α is too high, for example, when heat treatment is performed on a laminate of a printed circuit board, the upper and lower boards may shift due to thermal expansion and contraction, which may cause interference with signal transmission.

[0115] The glass fiber composition of the present invention preferably has a product of the thermal expansion coefficient α and the dielectric loss tangent tanδ (hereinafter sometimes referred to as α × tanδ) of 0.0009 or more, 0.001 or more, and particularly 0.0015 or more. If α × tanδ is too small, when the laminate of the glass fiber composite resin is heat-treated, there is a risk of damage to the glass fiber composite resin. On the other hand, the glass fiber composition of the present invention preferably has a product of α × tanδ of 0.2 or less, 0.15 or less, 0.14 or less, 0.12 or less, 0.1 or less, 0.095 or less, 0.09 or less, 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, 0.065 or less, 0.06 or less, 0.055 or less, 0.05 or less, 0.045 or less, 0.04 or less, 0.038 or less, 0.036 or less, and particularly 0.035 or less. If α × tanδ is too high, the values ​​of either the thermal expansion coefficient α or the dielectric loss tangent tanδ, or both, become large, and the low dielectric properties required for resin reinforcing materials such as printed circuit boards and communication equipment components will not be met.

[0116] The amount of water contained in glass is a characteristic that affects the dielectric constant ε and dielectric loss tangent tanδ of the glass, and can be determined by the β-OH value calculated by the following [Equation 1]. [Equation 1] β-OH = (1 / t) × log10(T1 / T2) β-OH: amount of water t: thickness of the glass T1: reference wavelength 3846 cm －１ Transmittance (%) at 2600 nm T2: Hydroxyl absorption wavelength 3600 cm －１ Transmittance (%) at 2800 nm

[0117] The glass fiber composition of the present invention preferably has a β-OH value of 0.1 / mm or more, 0.15 / mm or more, 0.19 / mm or more, 0.2 / mm or more, 0.23 / mm or more, 0.25 / mm or more, and particularly 0.26 / mm or more. If the β-OH value is too low, the network in the glass structure is broken, which tends to lower the viscosity of the glass. On the other hand, the glass fiber composition of the present invention preferably has a β-OH value of 0.8 / mm or less, 0.75 / mm or less, and particularly 0.7 / mm or less. If the β-OH value is too high, the network in the glass structure is broken, which causes local polarization, and tends to increase the dielectric constant ε and dielectric loss tangent tanδ of the glass.

[0118] The glass fibers of the present invention contain 95% or more of glass made from the glass fiber composition described above, on a solid content basis. If 95% or more of the glass fibers of the present invention are glass made from the glass fiber composition described above, and the remainder is an organic substance such as a coating agent, then scratches are less likely to occur on the glass fiber surface during various processing processes such as the glass fiber weaving process, and stable strength performance can be maintained. Furthermore, the glass fibers will be able to fully exhibit various physicochemical properties. The content of glass made from the glass fiber composition in the glass fibers of the present invention is 95 to 100% on a solid content basis, preferably 95.5 to less than 100%, 96 to 99.99%, and particularly preferably 96.5 to less than 99.99%. Here, the solid content basis is calculated by measuring the mass in a dry state where the moisture content of the glass surface is less than 0.1% by mass, then heat-treating it at a high temperature to remove the organic substance coated on the glass fiber surface by heating, measuring the mass, and calculating from the ratio of the two obtained masses.

[0119] Furthermore, if the glass fiber composition has a solid content of less than 95% by mass, the protective performance of the organic material applied to the surface of the glass fiber will not be significantly improved, and the amount of organic material required for application will increase, leading to higher manufacturing costs and making it uneconomical. Also, if the glass fiber composition has a solid content of more than 99.99% by mass, the protective performance of the glass fiber surface may not be fully realized.

[0120] In the glass fibers of the present invention, it is preferable that the coating agent on the surface of the glass fibers is 0.01% by mass or more relative to the total amount of glass fibers. If the amount of coating agent is too small, the protective effect on the glass fibers cannot be sufficiently obtained. On the other hand, in the glass fibers of the present invention, it is preferable that the coating agent on the surface of the glass fibers is 2.5% by mass or less relative to the total amount of glass fibers. If the amount of coating agent is too large, the amount of organic matter etc. used in the coating agent will increase, which may increase the manufacturing cost. Examples of components that can be used in the coating agent include starch, polyurethane resin, epoxy resin, vinyl acetate resin, acid copolymer, acrylic resin, modified polypropylene resin, carboxylic acid, polycarboxylic acid, polyester resin, antistatic agent, surfactant, antioxidant, antifungal agent, silane coupling agent, or lubricant.

[0121] Examples of the silane coupling agents mentioned above include γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, epoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and vinyltriethoxysilane. Depending on the type of resin to be compounded, these may be used individually or in combination of two or more types.

[0122] Examples of the above-mentioned surfactants include ethylene oxide propylene oxide alkyl ether, polyoxyethylene alkyl ether, polyoxyethylene-polyoxypropylene-block copolymer, alkyl polyoxyethylene-polyoxypropylene-block copolymer ether, polyoxyethylene fatty acid ester, polyoxyethylene fatty acid monoester, polyoxyethylene fatty acid diester, polyoxyethylene sorbitan fatty acid ester, glycerol fatty acid ester ethylene oxide adduct, polyoxyethylene castor oil ether, hydrogenated castor oil ethylene oxide adduct, alkylamine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, glycerol fatty acid ester, polyglycerin fatty acid ester, pentaerythritol fatty acid ester, sorbitol fatty acid ester, sorbitan fatty acid ester, and sucrose fat. Nonionic surfactants such as acid esters, polyhydric alcohol alkyl ethers, fatty acid alkanolamides, acetylene glycol, acetylene alcohol, ethylene oxide adducts of acetylene glycol, and ethylene oxide adducts of acetylene alcohol; cationic surfactants; anionic surfactants such as higher alcohol sulfate salts, higher alkyl ether sulfate salts, α-olefin sulfate salts, alkylbenzene sulfonates, α-olefin sulfonates, reaction products of fatty acid halides and N-methyl taurine, dialkyl sulfosuccinate salts, higher alcohol phosphate salts, and phosphate salts of higher alcohol ethylene oxide adducts; and amphoteric surfactants such as amino acid-type amphoteric surfactants, betaine-type amphoteric surfactants, and imidazoline-type amphoteric surfactants can be used, and these may be used alone or in combination of two or more types.

[0123] Examples of the above-mentioned lubricants include modified silicone oil, animal oil and its hydrogenated counterparts, vegetable oils such as soybean oil, rapeseed oil, coconut oil, palm oil, and peanut oil and their hydrogenated counterparts, animal waxes, vegetable waxes, mineral waxes, condensates of higher saturated fatty acids and higher saturated alcohols, triacylglycerols, paraffins, polyethyleneimines, polyalkylpolyamine alkylamide derivatives, fatty acid amides such as dehydrated condensates of polyethylene polyamines such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine with fatty acids such as lauric acid, myristic acid, palmitic acid, and stearic acid, and quaternary ammonium salts such as alkyltrimethylammonium salts such as lauryltrimethylammonium chloride. These may be used individually or in combination of two or more types.

[0124] The glass fibers of the present invention can be used in mixture with other fibers, as long as it does not hinder the objectives of the present invention. Examples of other fibers include glass fibers such as E glass fibers and S glass fibers, and fibers other than glass fibers such as carbon fibers and metal fibers.

[0125] The glass fibers of the present invention preferably have a diameter of 3 to 20 μm, and more preferably 3 to 10 μm. Within this range, the glass fibers can effectively exhibit their reinforcing properties.

[0126] The glass fibers of the present invention are preferably in the form of glass yarn, resin-reinforced glass cloth, or resin-impregnated printed circuit boards.

[0127] Glass yarn is made of twisted glass fibers. Preferably, the glass yarn contains 30 to 400 glass fibers and has a twist of 0 to 1.0 turns / 25 mm. It also preferably has a yarn count of 0.9 to 69 tex.

[0128] Glass cloth is a woven fabric containing glass fibers. Preferably, the warp thread density of the glass cloth is 40 to 120 threads / 25 mm, and the weft thread density is also preferably 40 to 120 threads / 25 mm.

[0129] The printed circuit board is an electronic circuit board containing glass cloth and thermoplastic resin. Preferably, the mass of the glass cloth in the printed circuit board is 10 to 90% of the total mass of the printed circuit board.

[0130] The thermoplastic resins mentioned above include polyethylene, polypropylene, polystyrene, styrene / maleic anhydride resin, styrene / maleimide resin, polyacrylonitrile, acrylonilyl / styrene (AS) resin, acrylonitrile / butadiene / styrene (ABS) resin, chlorinated polyethylene / acrylonitrile / styrene (ACS) resin, acrylonitrile / ethylene / styrene (AES) resin, acrylonitrile / styrene / methyl acrylate (ASA) resin, styrene / acrylonitrile (SAN) resin, methacrylic resin, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyamide, polyacetal, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polycarbonate, polyarylene sulfide, and polysulfone. Examples include polyethersulfone (PES), polyphenylsulfone (PPSU), polyphenylene ether (PPE), modified polyphenylene ether (m-PPE), polyarylether ketone, liquid crystal polymer (LCP), fluororesin, polyetherimide (PEI), polyetherether ketone, polyarylate (PAR), polysulfone (PSF), polyamideimide (PAI), polyaminobismaleimide (PABM), thermoplastic polyimide (TPI), polyethylene naphthalate (PEN), ethylene / vinyl acetate (EVA) resin, ionomer (IO) resin, polybutadiene, styrene / butadiene resin, polybutylene, polymethylpentene, olefin / vinyl alcohol resin, cyclic olefin resin, cellulose resin, polylactic acid, etc., and these may be used individually or in combination of two or more types.

[0131] Furthermore, the glass fibers of the present invention can also be used in forms other than those described above, such as glass chopped strands, glass fillers, continuous strand mats, knitted fabrics, glass rovings, and milled fibers, by being mixed with thermoplastic resins or thermosetting resins.

[0132] Examples of the thermosetting resins mentioned above include unsaturated polyester resins, vinyl ester resins, epoxy (EP) resins, melamine (MF) resins, phenolic (PF) resins, urethane (PU) resins, polyisocyanates, polyisocyanurates, polyimide (PI), urea (UF) resins, silicone (SI) resins, furan (FR) resins, benzoguanamine (BR) resins, alkyd resins, xylene resins, bismalade triazine (BT) resins, diallyl phthalate (PDAP) resins, and others. These may be used individually or in combination of two or more types.

[0133] The glass fiber composite material, which is a combination of the above-mentioned thermoplastic resin or thermosetting resin and glass fibers, can be molded using known molding methods such as injection molding, injection compression molding, two-color molding, hollow molding, foam molding (including supercritical fluid), insert molding, in-mold coating molding, extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, blow molding, stamping molding, infusion, hand lay-up, spray-up, resin transfer molding, sheet molding compound, bulk molding compound, pultrusion, and filament winding.

[0134] Next, the method for manufacturing glass fibers according to the present invention will be described. In the following description, the direct melt method (DM method) and the marble melt method (MM method) will be described as examples, but the method for manufacturing glass fibers according to the present invention is not limited to those described below.

[0135] First, a batch of glass raw materials, prepared to have the above composition (and properties), is placed in a glass melting furnace, where it is vitrified, melted, and homogenized. The composition is as described, and therefore the explanation is omitted here. Note that cullet may be used as part or all of the glass raw materials.

[0136] Next, glass fibers are obtained by continuously drawing molten glass from a bushing and forming it into fibers (DM method). Alternatively, glass fibers are obtained by first forming molten glass into a marbled shape, and then continuously drawing the remelted molten glass from a bushing and forming it into fibers (MM method).

[0137] The glass fibers formed in this manner according to the present invention are processed into glass yarn, glass cloth, etc., and used for various applications.

[0138] The present invention will be described in detail below based on the following examples. However, the following examples are merely illustrative, and the present invention is not limited in any way to these examples.

[0139] Tables 1 to 23 show examples of the present invention (samples No. 1 to 112) and comparative examples (samples No. 113 to 115).

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163] Each sample was prepared as follows:

[0164] First, various glass raw materials were weighed and mixed in predetermined amounts using arbitrary natural and / or chemical raw materials to achieve the glass composition shown in the table, thereby preparing glass raw material batches. Next, these glass raw material batches were placed in a 300cc platinum-rhodium crucible and heated and melted at 1550°C for 20 hours in an air atmosphere. In order to ensure the molten glass was homogeneous, the molten glass was stirred twice during the heating and melting process using a heat-resistant stirring rod. After the second stirring, the temperature was raised to 1650°C and held for 4 hours.

[0165] Subsequently, the homogenized molten glass was poured into a carbon mold to form an ingot measuring 60 mm x 170 mm x 1.5 mm. The resulting ingot was held at a constant temperature of 650-750°C for 30 minutes, then cooled at -3°C / min to (holding temperature -200°C), and finally cooled to room temperature at -10°C / min.

[0166] The properties of the obtained glass were measured as follows.

[0167] The dielectric constant ε and dielectric loss tangent tanδ at a frequency of 10 GHz were measured by cutting a glass sample measuring 50 mm × 50 mm × 0.15 mm from a molded ingot, polishing both sides to a mirror finish, and then measuring them at 25°C using the split-cylinder method with a 10 GHz resonator and vector analyzer.

[0168] The dielectric constant ε and dielectric loss tangent tanδ at a frequency of 40 GHz were measured by cutting a glass sample measuring 50 mm × 50 mm × 0.15 mm from a molded ingot, polishing both sides to a mirror finish, and then measuring them at 25°C using the split-cylinder method with a 40 GHz resonator and vector analyzer.

[0169] The viscosity of the molten glass is 10 ３．０ The spinning temperature Tx, corresponding to dPa·s, was measured by crushing the formed ingot, reheating it in a platinum crucible until it reached a molten state, and then measuring it using the platinum ball pulling method.

[0170] The liquidus temperature Ty was determined by crushing the molded ingot, passing the glass powder through a 500 μm sieve, and then filling a platinum container with the glass powder to an appropriate bulk density. The container was then placed in an indirect heating temperature gradient furnace set to a maximum temperature of 1470°C and left to stand for 16 hours in an atmospheric environment. After that, the platinum container containing the glass sample was removed, and the glass sample was taken out of the container. After the glass sample was slowly cooled to room temperature, the location where crystal precipitation began was identified using a polarizing microscope, and the crystal precipitation temperature was calculated from the temperature gradient in the indirect heating furnace.

[0171] The temperature difference ΔTxy between the spinning temperature Tx and the liquidus temperature Ty was calculated as (spinning temperature Tx) - (liquidus temperature Ty).

[0172] The density ρ was measured by the Archimedes method after cutting approximately 10 g of glass sample from the molded ingot.

[0173] The Young's modulus E was measured by cutting a glass sample measuring 40 mm x 20 mm x 2 mm from a molded ingot, polishing both main surfaces with a polishing solution dispersed with 1200-grade alumina powder, and then measuring the Young's modulus E on both polished main surfaces using a free-resonance type elastic modulus measuring device (manufactured by Nippon Techno Plus Co., Ltd.) at room temperature.

[0174] Acid resistance and alkali resistance tests were conducted according to the following procedure. After crushing the molded ingot, the glass powder was passed through a 500 μm sieve and deposited on a 300 μm sieve. The glass powder was then washed with deionized water and dried. A certain weight of the glass powder was taken out and transferred to a chemical-resistant container. A 10% hydrochloric acid solution or a 10% sodium hydroxide solution was added, and the mixture was shaken at 50 rpm in a constant temperature water bath at 80°C. The shaking of the glass powder was carried out for 90 hours in the acid resistance test and for 16 hours in the alkali resistance test. After drying the glass powder after shaking, its weight was measured, and the weight loss rate was calculated using the following formula [Formula 2]. [Formula 2] Weight loss rate = (Weight of glass powder before test - Weight of glass powder after test) / Weight of glass powder before test

[0175] The thermal expansion coefficient α was measured by cutting a glass sample from a molded ingot, processing it into a cylindrical shape with a diameter of 5 mm and a length of 20 mm, and then heating the cylindrical glass sample from 30°C to the bending point Tf. During this measurement process, the glass transition temperature Tg and bending point Tf were also measured.

[0176] α × tanδ was calculated by multiplying the measured thermal expansion coefficient α at 50–200°C by the dielectric loss tangent tanδ at 25°C and 10 GHz.

[0177] The β-OH value was measured using the following procedure. A 20 mm × 30 mm × 1 mm glass sample was cut from the prepared ingot, and both main surfaces were polished to a mirror finish. The transmittance of the glass sample was measured using FT-IR measurement with a spectrophotometer. From the obtained measurement values, the β-OH value was calculated using the above-mentioned [Equation 1].

[0178] As is clear from Tables 1 to 23, samples No. 1 to 112, which are examples that satisfy the glass composition of the present invention, all exhibited low dielectric properties, with a dielectric constant ε of 4.5 or less and a dielectric loss tangent tanδ of 0.0041 or less at 25°C and 40 GHz, and a dielectric constant ε of 4.5 or less and a dielectric loss tangent tanδ of 0.0037 or less at 25°C and 10 GHz. Furthermore, the Young's modulus E was 45 GPa or higher, and the coefficient of thermal expansion α at 50 to 200°C was 36 × 10⁻⁶ －７It exhibited sufficient strength and suitable thermal properties as a resin composite material, with a temperature of 0°C or less. In addition, in chemical resistance tests using 10% hydrochloric acid solution and 10% sodium hydroxide solution, the weight loss rate was 45% or less in both cases, demonstrating chemical resistance that can withstand plating and etching processes.

[0179] On the other hand, comparative examples No. 113 to 115 did not satisfy the glass composition of the present invention, and the dielectric constant and dielectric loss tangent at 25°C, 40GHz and 25°C, 10GHz, particularly the dielectric loss tangent, showed higher values ​​compared to the examples of the present application.

[0180] As described above, glass fibers, glass cloths, and glass fiber composite materials using the glass fiber composition of the present invention exhibit excellent performance and can be applied to all fields of industry.

[0181] Glass fibers, glass cloths, and glass fiber composite materials produced using the glass fiber composition of the present invention are expected to be used as reinforcing fibers for printed circuit boards and fiber-reinforced resin molded products, as well as in the casings and components of portable electronic devices such as smartphones, tablets, laptops, portable music players, and portable games. They are also expected to be used as communication components used in the millimeter-wave band, such as in-vehicle millimeter-wave radar, vehicle exterior components, vehicle interior components, vehicle engine components, electronic device casings, and electronic components. Furthermore, the glass composition of the glass fiber composition of the present invention can also be used as the composition of glass used in applications such as glass substrates, glass tubes, and glass containers.

Claims

1. As a glass composition, in mass %, SiO ２ 35 to 68%, Al ２ O ３ 0 to 40%, B ２ O ３ 5 to 40%, P ２ O ５ 0 to 12%, Li ２ O + Na ２ O + K ２ O + MgO + CaO + SrO + BaO + ZnO 0 to 5.5%, and further contains at least one selected from TiO ２ 、ZrO ２ 、Fe ２ O ３ 、MoO ３ 、Cr ２ O ３ 、SO ３ 、SnO ２ 、Pt, Rh. A glass fiber composition characterized by further containing at least one selected from the above.

2. Li ２ O + Na ２ O+K ２ The glass fiber composition according to claim 1, containing 0 to 0.3% of O + MgO + CaO + SrO + BaO + ZnO.

3. Li ２ O + Na ２ O+K ２ The glass fiber composition according to claim 2, containing 0.002 to 0.1% of O + MgO + CaO + SrO + BaO + ZnO.

4. As for the glass composition, in mass%, SiO ２ 45-57%, Al ２ O ３ 16-30%, B ２ O ３ 15-20.5%, P ２ O ５ 1-11.5%, SnO ２ 0.0001-0.5%, Li ２ O + Na ２ O+K ２ The glass fiber composition according to claim 1, characterized by containing 1 to 3.7% of O + MgO + CaO + SrO + BaO + ZnO.

5. As a glass composition, SiO is present in mass%. ２ 53-63%, Al ２ O ３ 5-15%, B ２ O ３ More than 20.5 to 31%, P ２ O ５ 0-5%, TiO ２ 0-5%, Li ２ O + Na ２ O+K ２ The glass fiber composition according to claim 1, characterized by containing 1 to 5.1% of O + MgO + CaO + SrO + BaO + ZnO.

6. SiO₂ by mass% ２ +B ２ O ３ A glass fiber composition according to any one of claims 1 to 3, containing 40 to 95%.

7. TiO ２ A glass fiber composition according to any one of claims 1 to 4, containing 0 to less than 2%.

8. By mass ratio, Na ２ O / (Li ２ O + Na ２ O+K ２ A glass fiber composition according to any one of claims 1 to 5, wherein O) is 0.001 to 1 or less.

9. A glass fiber composition according to any one of claims 1 to 5, wherein the dielectric constant ε at 25°C and 10 GHz is 6 or less, and the dielectric loss tangent tanδ is 0.008 or less.

10. A glass fiber composition according to any one of claims 1 to 5, wherein the dielectric constant ε at 25°C and 40 GHz is 6 or less, and the dielectric loss tangent tanδ is 0.01 or less.

11. The glass fiber composition according to any one of claims 1 to 5, wherein the spinning temperature Tx is 1560°C or less.

12. A glass fiber composition according to any one of claims 1 to 5, wherein the Young's modulus E at 25°C is 30 GPa or more.

13. The coefficient of thermal expansion α at 50-200°C is 40 × 10⁻⁶. －７ A glass fiber composition according to any one of claims 1 to 5, wherein the temperature is below / ℃.

14. A glass fiber composition according to any one of claims 1 to 5, wherein the product of the thermal expansion coefficient α at 50 to 200°C and the dielectric loss tangent tanδ at 25°C and 10 GHz is 0.0009 to 0.2 or less.

15. The glass fiber composition according to any one of claims 1 to 5, wherein the weight loss rate after immersion in a 10% by mass hydrochloric acid solution at 80°C for 90 hours is 60% or less.

16. The glass fiber composition according to any one of claims 1 to 5, wherein the weight loss rate after immersion in a 10% by mass sodium hydroxide solution at 80°C for 16 hours is 50% or less.

17. A glass fiber characterized by containing 95% by mass or more, on a solid content basis, of glass made from the glass fiber composition described in any one of claims 1 to 5.

18. Glass cloth containing glass fibers as described in claim 17.

19. A method for producing glass fibers, comprising the steps of: preparing a batch of glass raw materials to obtain a glass fiber composition according to any one of claims 1 to 5; melting the batch of glass raw materials to obtain molten glass; and forming the molten glass into fibers.

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