Glass fiber and composition for glass fiber

Abstract

Provided is a glass composition for glass fibers, which contains, in mass%, 50-65% of SiO2, 10-30% of Al2O3, 10-20% of MgO, 0-7% of CaO, 0-5% of TiO2, and 0-5% of ZrO2, the total content of SiO2, TiO2 and ZrO2 being 58% or more, the total content of TiO2 and ZrO2 being 0.1% or more, and when the content of MgO is 10% or more and less than 16%, 0.1% or more of ZrO2 being contained.

Description

Technical Field

[0001] The present invention relates to glass fibers and glass compositions suitable for glass fibers. Background Art

[0002] Most of the glass fibers for practical use are composed of glass compositions having a Young's modulus of 90 GPa or less. However, glass compositions having a Young's modulus exceeding 90 GPa are also known. For example, Patent Document 1 discloses a glass composition containing a large amount of rare earth oxides. Y in the glass composition of Patent Document 1 2 O 3 and La 2 O 3 The total content rate is in the range of 20 to 60% by weight. However, if the content rate of the rare earth oxides is high, the manufacturing cost increases. In consideration of this, Patent Document 2 discloses a technique for increasing the Young's modulus of a glass composition without requiring a large amount of rare earth oxides. The glass composition of Patent Document 2 contains 15 to 30% of MgO in terms of mol% as a component for increasing the Young's modulus.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: International Publication No. 2006 / 057405

[0006] Patent Document 2: Japanese Patent No. 6391875 Gazette Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In Patent Document 2, the acid resistance of the glass composition was not studied. Therefore, an object of the present invention is to provide glass fibers having a high Young's modulus and excellent acid resistance and a glass composition suitable for manufacturing such glass fibers.

[0009] Means for Solving the Problems

[0010] The present inventors repeatedly studied the mixing ratio of the glass components and completed a glass composition suitable for glass fibers having an excellent balance between acid resistance and Young's modulus.

[0011] The present invention provides a glass composition for glass fibers, which contains, in terms of mass%:

[0012] SiO 2 50 to 65%

[0013] Al 2 O 3 10 to 30%

[0014] MgO 10~20%

[0015] CaO 0~7%

[0016] TiO 2 0~5%

[0017] ZrO 2 0~5%

[0018] SiO 2 、TiO 2 and ZrO 2 The total content of is more than 58%,

[0019] TiO 2 and ZrO 2 The total content of is 0.1% or more,

[0020] When the content of MgO is 10% or more and less than 16%, 0.1% or more of ZrO is contained. 2 .

[0021] Furthermore, the present invention provides a glass fiber comprising the glass composition for glass fibers of the present invention.

[0022] Effects of the Invention

[0023] According to the present invention, it is possible to provide glass fibers having an excellent balance between acid resistance and Young's modulus, and a glass composition for glass fibers suitable for such glass fibers. DETAILED DESCRIPTION

[0024] The following is a description of an embodiment of the present invention, but the following description is not intended to limit the present invention to a specific embodiment. In this specification, the contents of the components of the glass composition are all expressed in mass %, and mass % is basically expressed as "%". In this specification, "substantially free of" and "substantially not containing" mean that the content is less than 0.1 mass%, less than 0.05 mass%, less than 0.01 mass, less than 0.005 mass, and further less than 0.003 mass, and depending on the situation, less than 0.001 mass%. "Substantially" means that trace amounts of impurities from glass raw materials, manufacturing equipment, etc. are allowed. "Alkali metal oxide" refers to Li 2 O、Na 2 O and K 2 O, sometimes written as R 2 O. The upper limit and the lower limit of the content described below may be arbitrarily combined in both the case where the upper limit and the lower limit are described separately and the case where the upper limit and the lower limit are described as a range.

[0025] [Glass composition]

[0026] <Component>

[0027] Hereinafter, each component that can constitute the glass composition of this embodiment will be described.

[0028] (SiO 2 )

[0029] SiO 2 is a component that forms the framework of the glass, adjusts the devitrification temperature and viscosity during glass formation, and improves acid resistance. SiO 2 The content rate is, for example, 50 to 65%. The lower limit of the content rate of SiO 2 can be 55% or more, 57% or more, 57.5% or more, 58% or more, 59% or more, 59.6% or more, 59.8% or more, and further 60% or more. The upper limit of the content rate of SiO 2 can be 63% or less, 62.3% or less, 62% or less, 61.8%, 61.5% or less, and further 61% or less. The content rate of SiO 2 can be 55 to 62%, and further can be 57.5 to 61.5%.

[0030] (Al 2 O 3 )

[0031] Al 2 O 3 is a component that adjusts the devitrification temperature and viscosity during glass formation and helps improve the water resistance of the glass. Al 2 O 3 The content rate is, for example, 10 to 30%. The lower limit of the content rate of Al 2 O 3 can be, for example, 15% or more, 17% or more, 19% or more, 19.5% or more, 19.7% or more, and further 20% or more. The upper limit of the content rate of Al 2 O 3 can be 28% or less, 25% or less, 22% or less, 21% or less, 20.8% or less, and further 20.6% or less. Al 2 O 3 The content rate can be 15 to 30%, and further 19.7 to 20.6%. However, as described later, when the content rate of MgO is in the range of less than 16%, the content rate of Al 2 O 3 can be 22 to 29%, and further 23.5 to 28%.

[0032] (B 2 O 3 )

[0033] B 2 O 3 is an optional component that forms the framework of the glass and adjusts the devitrification temperature and viscosity during glass formation. B 2 O 3 The content of B 2 O 3 is, for example, 0 to 1.5%. The lower limit of the content of B 2 O 3 can be 0.02% or more. The upper limit of the content of B 2 O 3 can be 1.2% or less, 1% or less, 0.5% or less, 0.3% or less, 0.1% or less, and further 0.08% or less. B

[0034] (MgO)

[0035] MgO is a component that helps to increase the Young's modulus and affects the devitrification temperature, viscosity, etc. The content of MgO is, for example, 10 to 20%. The lower limit of the content of MgO can be 12% or more, 14% or more, 16% or more, 16.5% or more, 16.6% or more, 16.8% or more, and further 17% or more. The upper limit of the content of MgO can be 19% or less, 18% or less, 17.8% or less, 17.7% or less, and further 17.6% or less. The content of MgO can be 12 to 20%, and further 14 to 19%. When the content of MgO is less than 16%, the addition of ZrO 2 is recommended.

[0036] (CaO)

[0037] CaO is an optional component that adjusts the devitrification temperature and viscosity during glass formation. The content of CaO is, for example, 0 to 7%. The lower limit of the content of CaO can be 0.1% or more, 0.3% or more, 0.5% or more, and further 0.7% or more. The upper limit of the content of CaO can be 5% or less, 3% or less, 2% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, and further 1% or less.

[0038] (alkali metal oxide)

[0039] Alkali metal oxide (R 2 O) is an optional component that adjusts the devitrification temperature and viscosity during glass formation. The total content of alkali metal oxide, specifically [Li 2 O] + [Na 2 O] + [K 2O] is, for example, 0 to 3%. The lower limit of the content rate of the alkali metal oxide can be 0.05% or more, 0.1% or more, 0.2% or more, and further 0.3% or more. R 2 The upper limit of the content rate of O can be 2% or less, 1.5% or less, 1.2% or less, 1.0% or less, 0.9% or less, and further 0.8% or less. If R 2 the content rate of O is high, there is a case where the Young's modulus does not sufficiently increase.

[0040] Li 2 The content rate of O is, for example, 0 to 1.5%. Li 2 The lower limit of the content rate of O is 0.1% or more, 0.2% or more, and can also be 0.3% or more, and further 0.4% or more. Li 2 The upper limit of the content rate of O can be 1% or less, 0.8% or less, 0.6% or less, and further 0.5% or less. Li 2 A preferable example of the content rate of O is 0.1 to 0.8%. In terms of suppressing the influence of reducing the Young's modulus and adjusting characteristics such as the devitrification temperature at the same time, Li 2 O is more advantageous than Na 2 O and K 2 O. Li 2 The content rate of O can be higher than that of Na 2 O, can be higher than that of K 2 O, and can also be higher than the sum of the content rates of Na 2 O and K 2 O. However, Li 2 O may also be substantially not contained.

[0041] Na 2 The content rate of O is, for example, 0 to 1%. Na 2 The upper limit of the content rate of O can be 0.5% or less, 0.2% or less, 0.18% or less, 0.15% or less, 0.13% or less, 0.1% or less, and further 0.08% or less. Na 2 O may also be substantially not contained. K 2 The content rate of O is, for example, 0 to 0.5%. K 2 The upper limit of the content rate of O can be 0.3% or less, 0.1% or less, 0.08% or less, and further 0.06% or less, and further 0.04% or less. K 2 O may also be substantially not contained.

[0042] Na 2 The content rate of O and K 2 The sum of the content rates of O can be in the range of 0 to 1%, 0 to 0.5%, and further 0 to 0.3%.

[0043] (TiO 2 and ZrO 2 )

[0044] TiO 2 and ZrO 2 are optional components that can contribute to improving acid resistance. However, it is preferable to add at least one selected from TiO 2 and ZrO 2 . In particular, it has been found that ZrO 2 is a component that can supplement the effect of increasing the Young's modulus brought about by MgO. The lower limit of the total content of TiO 2 and ZrO 2 can be 0.1% or more, 0.3% or more, 0.5% or more, 0.8% or more, 1% or more, and further 1.5% or more. The upper limit of the total content of TiO 2 and ZrO 2 can be 5% or less, 4% or less, 3.5% or less, 3% or less, and further 2.5% or less. In this embodiment, for example, the total content of TiO 2 and ZrO 2 can also be in the range of 0.5 - 5%, 0.8 - 4%, 1 - 3.5%.

[0045] TiO 2 and ZrO 2 are added in a range of, for example, 0 - 5% respectively. The content of TiO 2 and the content of ZrO 2 can also be 0.1% or more, 0.3% or more, 0.5% or more, 1% or more, and further 1.2% or more respectively. The content of TiO 2 and the content of ZrO 2 can be 4% or less, 3% or less, 2.5% or less, and further 2% or less respectively. However, TiO 2 or ZrO 2 can also be substantially not contained.

[0046] (ZnO)

[0047] ZnO is an optional component that is allowed to be added. ZnO is added, for example, in a range of 0 - 3%, and further in a range of 0 - 1.5%. The upper limit of the content of ZnO can be 1.4% or less, 1% or less, and further 0.5% or less. ZnO can be substantially not contained.

[0048] (F 2 )

[0049] F 2It is also an optional component that can be added for clarification, etc. 2 For example, it is added in the range of 0 to 0.5%, and further in the range of 0 to 0.1%. 2 The upper limit of the content of F may be 0.08% or less. 2 It may not be substantially contained.

[0050] (SiO 2 +TiO 2 +ZrO 2 )

[0051] SiO 2 、TiO 2 and ZrO 2 The total content of SiO 2 +TiO 2 +ZrO 2 ) is, for example, 58% or more. SiO 2 、TiO 2 and ZrO 2 The total content of can be 58.5% or more, 59% or more, 59.5% or more, 60% or more, 60.5% or more, and further 61% or more. (SiO 2 +TiO 2 +ZrO 2 ) glass composition is suitable for achieving excellent acid resistance. 2 +TiO 2 +ZrO 2 ) is not particularly limited, and is, for example, 63.5% or less, 63% or less, and further, 62.5% or less.

[0052] (SiO 2 +Al 2 O 3 +MgO)

[0053] SiO 2 、Al 2 O 3 The total content of the components of SiO and MgO ( 2 +Al 2 O 3 +MgO) can be 95% or more, 96% or more, 97% or more, and further 97.5% or more. 2 +Al 2 O 3 +MgO) can be, for example, 99% or less, and further 98.5% or less.

[0054] (CaO+R 2 O)

[0055] The addition of CaO and alkali metal oxides (R 2 O) is suitable for adjusting the devitrification temperature of the glass composition. The total content of CaO and the content of R 2 O (CaO + R 2 O) can be 0 to 2.5%. The lower limit of (CaO + R 2 O) can be 0.05% or more, 0.1% or more, 0.3% or more, 0.5% or more, 0.7% or more, and further 1% or more. The upper limit of (CaO + R 2 O) can be 2.3% or less, 2.2% or less, 2% or less, and further 1.8% or less.

[0056] (Other components)

[0057] The glass composition may contain components other than the above. As other components that the glass composition may contain, Fe 2 O 3 , Y 2 O 3 , La 2 O 3 , SrO, BaO, Cl 2 , SnO 2 , CeO 2 , P 2 O 5 , SO 3 .

[0058] Fe 2 O 3 is added, for example, in the range of 0 to 1%. The upper limit of the content of Fe 2 O 3 can be 0.5%, 0.3% or less, 0.2% or less, 0.15% or less, and further 0.1% or less. Fe 2 O 3 may also be substantially absent. It should be noted that a part of the iron oxide exists as FeO in the glass composition, but its content is conventionally converted to Fe 2 O 3 for representation.

[0059] Y 2 O 3 and La 2 O 3 are optional components that help to increase the Young's modulus. However, the raw materials of these components are relatively expensive. Y 2 O 3 and La 2 O 3 The total content of, for example, is 0 to 5%. Y 2 O 3 and La2 O 3 The upper limit of the total content ratio of O can be 3% or less, 2% or less, 1% or less, and further 0.5% or less. Y 2 O 3 It may also be substantially free of. La 2 O 3 It may also be substantially free of.

[0060] SrO, BaO, Cl 2 , SnO 2 , CeO 2 , P 2 O 5 and SO 3 The content ratios of these components are, for example, 0 to 0.5% respectively. The upper limit of the content ratio of each of these components can be 0.3% or less, 0.2% or less, and further 0.1% or less. Each of these components may also be substantially free of.

[0061] (Composition Example A containing 16% or more of MgO)

[0062] The glass composition of this embodiment may contain the following components.

[0063] Containing:

[0064] SiO 2 50 - 65%

[0065] B 2 O 3 0 - 1.5%

[0066] Al 2 O 3 10 - 25%

[0067] MgO 16 - 20%

[0068] CaO 0 - 7%

[0069] Li 2 O 0 - 1.0%

[0070] Na 2 O 0 - 0.2%

[0071] K 2 O 0 - 0.1%

[0072] TiO 2 0 - 5%

[0073] ZrO 2 0 - 5%

[0074] SiO 2 , TiO 2and ZrO 2 The total content rate is 58% or more,

[0075] TiO 2 and ZrO 2 The total content rate is 0.1% or more.

[0076] (The content rate of MgO is less than 16%, including ZrO 2 Composition Example B)

[0077] The glass composition of this embodiment may contain the following components.

[0078] Containing:

[0079] SiO 2 50 - 65%

[0080] B 2 O 3 0 - 1.5%

[0081] Al 2 O 3 10 - 30%

[0082] MgO 10 - 16% (excluding 16%)

[0083] CaO 0 - 7%

[0084] Li 2 O 0 - 1.0%

[0085] Na 2 O 0 - 0.2%

[0086] K 2 O 0 - 0.1%

[0087] TiO 2 0 - 5%

[0088] ZrO 2 0.1 - 5%

[0089] SiO 2 、TiO 2 and ZrO 2 The total content rate is 58% or more.

[0090] In Composition Example B, the content rate of each component can also be appropriately adjusted with reference to the above range. However, the content rate of Al 2 O 3 can be adjusted slightly higher, for example, it can be 22 - 29%, further 23.5 - 28%.

[0091] (Composition Example C with particularly excellent acid resistance)

[0092] The glass composition of this embodiment may contain the following components.

[0093] Containing:

[0094] SiO 2 55 - 65%

[0095] B 2 O 3 0 - 1.5%

[0096] Al 2 O 3 10 - 28%

[0097] MgO 10 - 20%

[0098] CaO 0 - 7%

[0099] Li 2 O 0 - 1.0%

[0100] Na 2 O 0 - 0.2%

[0101] K 2 O 0 - 0.1%

[0102] TiO 2 0 - 5%

[0103] ZrO 2 1.2 - 5%

[0104] SiO 2 、TiO 2 and ZrO 2 The total content rate of is 60.4% or more.

[0105] The content rate of ZrO in Composition Examples A - C 2 can be 1.5 - 3%.

[0106] <Properties>

[0107] (Young's modulus)

[0108] The Young's modulus of the glass composition of this embodiment is, for example, 98 GPa or more. The lower limit of the Young's modulus can be 99 GPa or more, 99.5 GPa or more, and depending on the situation, 100 GPa or more. The upper limit of the Young's modulus is not particularly limited and can be, for example, 115 GPa or less, further 110 GPa or less.

[0109] (Acid resistance)

[0110] The acid resistance can be evaluated by the mass reduction rate ΔW (%) obtained from the tests described in the Examples section. The ΔW of the glass composition of the present embodiment is, for example, 0.3 mass% or less. The upper limit of ΔW can also be set to 0.25 mass% or less, and further to 0.1 mass% or less.

[0111] [Glass fiber]

[0112] The glass composition of the present embodiment is suitable for the manufacture of glass fibers. The glass fibers can be continuous glass fibers or chopped glass fibers. The glass fibers can be in a form corresponding to at least one selected from, for example, strands, rovings, yarns, fabrics, chopped strands, glass wool, and milled fibers. The fabric can be a roving fabric or a yarn fabric.

[0113] However, due to its excellent properties, the glass composition in each of the above forms can also be used as a glass-formed body other than glass fibers. An example of the glass-formed body is particulate glass. The particulate glass can be manufactured by finely breaking it to the extent that it loses the shape of a glass fiber, or by using a nozzle corresponding to the target shape in the same way as glass fibers. The glass composition in each of the above forms is also suitable for manufacturing particulate glass while avoiding devitrification. In one aspect of the present invention, the particulate glass contains the glass composition in each of the above forms, or is composed of the glass composition in each of the above forms.

[0114] The particulate glass can, for example, correspond to at least one selected from flaky glass, glass powder, glass beads, and fine flakes. The particulate glass can be used for FRP, that is, for reinforcing a reinforcing material typified by a resin and the like.

[0115] Considering that it can also be used for particulate glass, the above glass composition can also be regarded as a glass composition for glass fibers or particulate glass.

[0116] [Non-woven fabric, cord for rubber reinforcement]

[0117] Each glass fiber provided by the present invention can be used for the same uses as conventional glass fibers. According to one aspect of the present invention, a glass fiber non-woven fabric containing glass fibers is provided. In addition, according to one aspect of the present invention, a cord for rubber reinforcement containing a roving formed by bundling glass fibers is provided. The glass fibers can also be used for other purposes. Other purposes include reinforcing a reinforcing body typified by a resin.

[0118] [Examples]

[0119] Hereinafter, the embodiments of the present invention will be described more specifically with reference to Examples and Comparative Examples. It should be noted that, in the following tables, the content ratios of the components are also expressed in mass%.

[0120] <Preparation of Glass Composition>

[0121] Usual glass raw materials such as silica sand were blended to obtain the compositions shown in Tables 1 and 2, and batches of glass raw materials were prepared according to each example and comparative example. Each batch was heated to 1500 - 1600 °C using an electric furnace to melt it, and maintained in this state for about 4 hours until the composition became uniform. Then, a part of the molten glass (glass melt) was poured out onto an iron plate and annealed to room temperature in the electric furnace to obtain a glass composition (plate-like object, glass specimen) as a block. For these glass compositions, the properties were evaluated as follows. The results are shown together in Tables 1 and 2.

[0122] (Young's Modulus)

[0123] Young's modulus was obtained as follows: By the usual ultrasonic method, the longitudinal wave velocity vl and the transverse wave velocity vt of the elastic wave propagating in the glass were measured, and based on the density ρ of the glass measured separately by the Archimedes method, it was obtained by the formula E = 3ρ·v t 2 ·(v l 2 - 4 / 3·v t 2 ) / (v l 2 - v t 2 )).

[0124] (Acid Resistance)

[0125] Glass single fibers with a diameter of 15 μm were cut into a length of 20 mm, weighed in grams equal to the specific gravity of the glass, and the mass reduction rate when the glass fibers were immersed in 80 mL of a sulfuric acid aqueous solution at 99 °C and a specific gravity of 1.2 for 60 minutes was obtained. This mass reduction rate was designated as ΔW.

[0126] It should be noted that the above mass reduction rate was calculated based on the following formula, where the mass before immersion was designated as Wa and the mass after immersion was designated as Wb.

[0127] Mass reduction rate (%) = {(Wa - Wb) / Wa} × 100

[0128] [Table 1]

[0129]

[0130] [Table 2]

[0131]

[0132] According to each example, a Young's modulus of 98 GPa or more and a ΔW of 0.3 mass% or less were achieved. On the other hand, in each comparative example, these properties could not be satisfied.

[0133] As described above, this specification discloses the following technologies.

[0134] (Technology 1)

[0135] A glass composition for glass fibers, expressed in mass %, contains:

[0136] SiO 2 50 - 65%

[0137] Al 2 O 3 10 - 30%

[0138] MgO 10 - 20%

[0139] CaO 0 - 7%

[0140] TiO 2 0 - 5%

[0141] ZrO 2 0 - 5%,

[0142] SiO 2 、TiO 2 and ZrO 2 The total content rate of SiO, TiO, and ZrO is 58% or more.

[0143] TiO 2 and ZrO 2 The total content rate of TiO and ZrO is 0.1% or more.

[0144] When the content rate of MgO is 10% or more and less than 16%, it contains 0.1% or more of ZrO 2 .

[0145] (Technology 2)

[0146] The glass composition according to Technology 1, which, expressed in mass %, contains:

[0147] SiO 2 55 - 62%

[0148] Al 2 O 3 15 - 30%

[0149] MgO 12 - 20%

[0150] CaO 0 - 4%

[0151] TiO 2 0 - 3%

[0152] ZrO 2 0 - 3%.

[0153] (Technology 3)

[0154] For the glass composition according to Technology 1 or 2, the total content of TiO, expressed in mass%, and the content of ZrO 2 is 0.5% or more and 5% or less. 2

[0155] (Technology 4)

[0156] For the glass composition according to any one of Technologies 1 to 3, wherein the content of SiO, expressed in mass%, is in the range of 57.5 to 61.5%. 2

[0157] (Technology 5)

[0158] For the glass composition according to any one of Technologies 1 to 4, wherein the content of Li 2 O is in the range of 0 to 1.5%.

[0159] (Technology 6)

[0160] For the glass composition according to any one of Technologies 1 to 5, wherein the total content of Na 2 O and the content of K 2 O is in the range of 0 to 1%.

[0161] (Technology 7)

[0162] For the glass composition according to any one of Technologies 1 to 6, wherein the content of B 2 O 3 is in the range of 0 to 1.5%.

[0163] (Technology 8)

[0164] For the glass composition according to any one of Technologies 1 to 7, wherein the total content of Y 2 O and the content of La 3 O 2 is in the range of 0 to 5%. 3

[0165] (Technology 9)

[0166] For the glass composition according to any one of Technologies 1 to 8, its Young's modulus is 98 GPa or more.

[0167] (Technology 10)

[0168] For the glass composition according to any one of Technologies 1 to 9, wherein ΔW is 0.3 mass% or less.

[0169] ​​​Here, the above ΔW is the mass reduction rate when the above glass composition with a mass set to the same value as the specific gravity of the above glass composition is immersed in 80 mL of sulfuric acid solution with a specific gravity of 1.2 and a temperature of 99 °C for 60 minutes.

[0170] (Technology 11)

[0171] A glass fiber comprising the glass composition according to any one of Technologies 1 to 10.

[0172] (Technology 12)

[0173] The glass fiber according to Technology 11, having a form conforming to at least one selected from the group consisting of strand, roving, yarn, fabric, chopped strand, glass wool, and milled fiber.

Claims

1. A glass composition for glass fibers, wherein, in terms of mass %, it contains: SiO 2 50% to 65% Al 2 O 3 10% to 30% MgO 10% - 20% CaO 0% - 7% TiO 2 0% to 5% ZrO 2 0% to 5%, SiO 2 、TiO 2 and ZrO 2 The total content ratio is 58% or more. TiO 2 and ZrO 2 The total content ratio is 0.1% or more. When the MgO content is 10% or more and less than 16%, it contains 0.1% or more of ZrO 2 .

2. The glass composition according to claim 1, wherein, in terms of mass %, it contains: SiO 2 55% to 62% Al 2 O 3 15% to 30% MgO 12% - 20% CaO 0% - 4% TiO 2 0% to 3% ZrO 2 0% to 3%.

3. The glass composition according to claim 1, wherein, In terms of mass %, the total content rate of TiO 2 and the content rate of ZrO 2 is 0.5% or more and 5% or less.

4. The glass composition according to claim 1, wherein, The content of SiO, expressed in mass%, is in the range of 57.5% to 61.5%. 2 ​ 5. The glass composition according to claim 1, wherein, In terms of mass%, the content of Li 2 O is in the range of 0% to 1.5%.

6. The glass composition according to claim 1, wherein, In terms of mass percentage, the content of Na 2 O and the content of K 2 O have a total content in the range of 0% to 1%.

7. The glass composition according to claim 1, wherein, In terms of mass percentage, B 2 O 3 has a content rate in the range of 0% to 1.5%.

8. The glass composition according to claim 1, wherein, In terms of mass%, the content of Y 2 O 3 and the content of La 2 O 3 add up to be in the range of 0% to 5%.

9. The glass composition according to claim 1, having a Young's modulus of 98 GPa or more.

10. The glass composition according to claim 1, wherein, ΔW is 0.3 mass % or less, herein, the ΔW is the mass reduction rate when the glass composition with the number of grams of the mass set to the same value as the specific gravity of the glass composition is immersed in 80 mL of sulfuric acid at a specific gravity of 1.2 and a temperature of 99 °C for 60 minutes.

11. A glass fiber containing the glass composition according to any one of claims 1 to 10.

12. The glass fiber according to claim 11, having a form conforming to at least one selected from the group consisting of a strand, roving, yarn, fabric, chopped strand, glass wool, and milled fiber.

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