Glass composition, glass fiber, glass filler, glass fiber production method, and glass filler production method

Abstract

Provided is a glass composition wherein, in mass%, 45≤SiO2≤65, 1≤B2O3≤10, 14≤Al2O3≤21, 1≤MgO≤15, 2≤CaO≤21, 5≤MgO+CaO≤22, 0.1≤Li2O+Na2O+K2O≤3, and 1<T-Fe2O3≤10, and the mass ratio calculated from MgO / (MgO+CaO) is 0.05-0.88 inclusive.

Description

Glass composition, glass fiber, glass filler, method for manufacturing glass fiber, and method for manufacturing glass filler

[0001] The present invention relates to a glass composition, glass fibers, glass filler, a method for producing glass fibers, and a method for producing glass filler.

[0002] Glass, primarily made from silica (SiO2), has long been used for bottles and window panes. With advancements in processing technology, glass is now widely used not only as sheet glass but also as a filler in resins and concrete, in the form of glass fibers and flakes.

[0003] The composition of glass significantly influences the physical and mechanical properties of plate glass, as well as glass fibers and flake-like glass processed from glass.

[0004] For example, E-glass, which minimizes the content of alkaline components (Na₂O, K₂O), has excellent electrical insulation properties but suffers from poor elastic modulus. Furthermore, S-glass has been developed, offering improved elastic modulus and strength compared to E-glass.

[0005] S-glass possesses higher elastic modulus and strength than E-glass, while also exhibiting excellent heat resistance, making it suitable for use as a reinforcing material for rubber cords and resins. However, S-glass is difficult to manufacture due to its high melting and working temperatures.

[0006] Furthermore, according to Non-Patent Document 1, both E-glass and S-glass either do not contain iron oxide or their iron oxide content is less than 1% by mass.

[0007] Patent Document 1 discloses a highly elastic composition for glass fibers, comprising SiO2, Al2O3, MgO, Fe2O3, TiO2, CaO, and the like.

[0008] Patent Document 2 discloses glass for mineral fibers, comprising SiO2, Al2O3, Na2O, CaO, Fe2O3, K2O, MgO, etc.

[0009] Patent Document 3 discloses a method for producing mineral wool and mineral wool composed of SiO2, Al2O3, Na2O, CaO, Fe2O3, K2O, MgO, etc.

[0010] Special Publication No. 2020-529378 Publication Special Publication No. 2022-502331 Publication Special Publication No. 6-503799

[0011] Yamane, Masayuki et al. (eds.), "Glass Engineering Handbook (Popular Edition)," 1st edition, Asakura Shoten Co., Ltd., 1999, 514 pages.

[0012] Conventional glass compositions require a low molding temperature, i.e., a low molding temperature, and improved elastic modulus and moldability.

[0013] Therefore, the present invention aims to provide a glass composition that has a low molding temperature, a high modulus of elasticity, and improved moldability.

[0014] As a result of diligent research, the inventors of the present invention discovered that by appropriately adjusting the components contained in the glass composition, a glass composition with a low molding temperature, high elastic modulus, and improved moldability can be obtained, thus completing the present invention.

[0015] Furthermore, the inventors have also found that the above-mentioned glass composition can be obtained inexpensively and efficiently by using coal ash (fly ash) as a raw material.

[0016] The present invention provides a glass composition in which, expressed in mass%, 45 ≤ SiO2 ≤ 65, 1 ≤ B2O3 ≤ 10, 14 ≤ Al2O3 ≤ 21, 1 ≤ MgO ≤ 15, 2 ≤ CaO ≤ 21, 5 ≤ MgO + CaO ≤ 22, 0.1 ≤ Li2O + Na2O + K2O ≤ 3, and 1 < T - Fe2O3 ≤ 10, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.88 or less.

[0017] In another aspect, the present invention provides a glass composition which, expressed in mass%, satisfies: 45≦SiO₂≦65, 0.1≦B₂O₃≦8, 14≦Al₂O₃≦21, 1≦MgO≦15, 4≦CaO≦21, 5≦MgO+CaO≦22, 0≦Li₂O+Na₂O+K₂O≦4, 1<T-Fe₂O₃≦10, is substantially free of T-MnO₂, and has a mass ratio calculated by MgO / (MgO+CaO) of 0.05 or more and 0.79 or less.

[0018] In still another aspect, the present invention provides a glass composition which, expressed in mass%, satisfies: 45≦SiO₂≦65, 0≦B₂O₃≦10, 14≦Al₂O₃≦19, 2≦MgO≦15, 3≦CaO≦20, 5≦MgO+CaO≦22, 0≦BaO≦10, 0≦Li₂O+Na₂O+K₂O≦3, 0≦TiO₂≦5, 1<T-Fe₂O₃≦9, and has a mass ratio calculated by MgO / (MgO+CaO) of 0.05 or more and 0.83 or less.

[0019] Furthermore, the present invention provides a glass fiber formed of the above glass composition.

[0020] Furthermore, the present invention provides a glass filler formed of the above glass composition.

[0021] Furthermore, the present invention provides a method for producing a glass fiber, comprising: a step of melting the above glass composition; and a step of spinning the molten glass composition to form a glass fiber.

[0022] Furthermore, the present invention provides a method for producing a glass filler, comprising: a step of melting the above glass composition; and a step of molding the molten glass composition into a glass filler.

[0023] According to the present invention, a glass composition having a low molding temperature, a high elastic modulus and improved moldability can be provided.

[0024] It is a perspective view schematically showing an example of scaly glass. It is a plan view of the scaly glass shown in FIG. 1A as viewed from the upper surface thereof. It is a schematic diagram for explaining an example of an apparatus and a method for producing scaly glass. It is a schematic diagram for explaining another example of an apparatus and a method for producing scaly glass. It is a schematic diagram for explaining an example of a spinning apparatus that can be used for producing chopped strands. It is a schematic diagram for explaining an example of an apparatus for producing chopped strands from a strand wound body obtained by the spinning apparatus shown in FIG. 4. It is a perspective view showing an example of a concrete product. It is an enlarged cross-sectional view of the concrete product shown in FIG. 6A. It is a diagram showing another example of a concrete product.

[0025] Hereinafter, the present invention will be described in detail, but the following description is not intended to limit the present invention to any specific embodiment.

[0026] [Glass Composition] <Composition> In the glass composition of one aspect of the present invention, the content ratios of SiO2, B2O3, Al2O3, MgO, CaO, Li2O, Na2O, K2O, and T-Fe2O3, expressed in % by mass, satisfy: 45 ≤ SiO2 ≤ 65, 1 ≤ B2O3 ≤ 10, 14 ≤ Al2O3 ≤ 21, 1 ≤ MgO ≤ 15, 2 ≤ CaO ≤ 21, 5 ≤ MgO + CaO ≤ 22, 0.1 ≤ Li2O + Na2O + K2O ≤ 3, 1 < T-Fe2O3 ≤ 10, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.88 or less.

[0027] In addition, in the glass composition of another aspect of the present invention, the content ratios of SiO2, B2O3, Al2O3, MgO, CaO, Li2O, Na2O, K2O, T-Fe2O3, and T-MnO2, expressed in % by mass, satisfy: 45 ≤ SiO2 ≤ 65, 0.1 ≤ B2O3 ≤ 8, 14 ≤ Al2O3 ≤ 21, 1 ≤ MgO ≤ 15, 4 ≤ CaO ≤ 21, 5 ≤ MgO + CaO ≤ 22, 0 ≤ Li2O + Na2O + K2O ≤ 4, 1 < T-Fe2O3 ≤ 10, T-MnO2 is not substantially contained, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.79 or less.

[0028] Furthermore, in yet another embodiment of the glass composition of the present invention, the content of SiO2, B2O3, Al2O3, MgO, CaO, BaO, Li2O, Na2O, K2O, TiO2, and T-Fe2O3, expressed in mass%, is such that 45 ≤ SiO2 ≤ 65, 0 ≤ B2O3 ≤ 10, 14 ≤ Al2O3 ≤ 19, 2 ≤ MgO ≤ 15, 3 ≤ CaO ≤ 20, 5 ≤ MgO + CaO ≤ 22, 0 ≤ BaO ≤ 10, 0 ≤ Li2O + Na2O + K2O ≤ 3, 0 ≤ TiO2 ≤ 5, and 1 < T-Fe2O3 ≤ 9, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.83 or less.

[0029] In glass compositions, iron oxide typically exists as Fe₂O₃ or FeO. Therefore, the iron oxide present as FeO is converted to Fe₂O₃, and the combined content of this iron oxide with that present as Fe₂O₃ is considered the total iron oxide content in the glass composition, and is conventionally denoted as T-Fe₂O₃. In addition, manganese oxide is known to typically exist as MnO, Mn₂O₃, or MnO₂ in glass compositions. Therefore, the manganese oxide present as MnO or Mn₂O₃ is converted to MnO₂, and the combined content of this manganese oxide with that present as MnO₂ is considered the total manganese oxide content in the glass composition, and is conventionally denoted as T-MnO₂. Furthermore, tin oxide typically exists as SnO₂ or SnO in glass compositions. Therefore, the iron oxide present as SnO is converted to SnO2, and the combined content with the tin oxide present as SnO2 is taken as the total tin oxide content in the glass composition, and is conventionally denoted as T-SnO2.

[0030] In this specification, "substantially absent" means a content of less than 0.1% by mass, preferably less than 0.05% by mass, more preferably less than 0.01% by mass, even more preferably less than 0.005% by mass, particularly preferably less than 0.003% by mass, and most preferably less than 0.001% by mass. The content, properties, and other preferred ranges of each component can be adopted by any combination of the upper and lower limits described individually below. Furthermore, the content of each component can be any combination to constitute a glass composition.

[0031] The following provides a detailed explanation of each component of the glass composition.

[0032] (SiO2) SiO2 is a component that forms the framework of the glass composition. It also adjusts the devitrification temperature and viscosity during glass composition formation, and improves the strength and acid resistance of the glass composition. The SiO2 content in the glass composition is between 45% by mass and 65% by mass. If the SiO2 content in the glass composition is less than 45% by mass, the devitrification temperature becomes high, making it difficult to obtain homogeneous glass. In this case, the strength and acid resistance of the glass composition may also decrease. Furthermore, in this case, the viscosity of the molten material is too low, resulting in poor moldability. On the other hand, if the SiO2 content exceeds 65% by mass, the melting point of the raw material mixture becomes excessively high, making it difficult to maintain a uniform composition of the molten material in the melting furnace during mass production of the glass composition using a melting furnace. In this case, the Young's modulus of the glass composition may also decrease. The lower limit of the SiO2 content in the glass composition is, for example, 46% by mass or more, and preferably 47% by mass or more, 48% by mass or more, 49% by mass or more, 50% by mass or more, and 51% by mass or more. The lower limit of SiO2 may be 52% by mass or more, 53% by mass or more, 54% by mass or more, 55% by mass or more, and greater than 55% by mass. The upper limit of the SiO2 content is, for example, 64% by mass or less, and preferably 63% by mass or less, 62% by mass or less, 61% by mass or less, 60% by mass or less, 59% by mass or less, and 58% by mass or less. The upper limit of SiO2 may be 57% by mass or less, 56% by mass or less, and less than 56% by mass. The SiO2 content is, for example, 48% by mass ≤ SiO2 ≤ 64% by mass, and more specifically 50% by mass ≤ SiO2 ≤ 58% by mass.

[0033] (B2O3) B2O3, like SiO2 and Al2O3, can form the framework of a glass composition. By including B2O3 in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass production. Therefore, the glass composition may contain B2O3. However, if the glass composition contains an excessive amount of B2O3, its acid resistance and alkali resistance will decrease. In this case, the Young's modulus of the glass composition tends to decrease. The B2O3 content in the glass composition is, for example, 0% by mass or more and 10% by mass or less. The lower limit of the B2O3 content is, for example, 0.1% by mass or more, and it is preferable that it is 0.5% by mass or more, 1% by mass or more, or more than 1% by mass. The lower limit of the B2O3 content may be 1.5% by mass or more, 2% by mass or more, 2.5% by mass or more, 3% by mass or more, more than 3% by mass, 3.5% by mass or more, or 4% by mass or more. Furthermore, the upper limit of the B2O3 content is, for example, 9% by mass or less, and preferably 8% by mass or less, 7% by mass or less, 6% by mass or less, or 5% by mass or less. Note that B2O3 may not be substantially present. The B2O3 content may be 0% by mass ≤ B2O3 ≤ 8% by mass, 0.1% by mass ≤ B2O3 ≤ 8% by mass, 0.1% by mass ≤ B2O3 ≤ 7% by mass, 1% by mass ≤ B2O3 ≤ 10% by mass, 1% by mass ≤ B2O3 ≤ 8% by mass, and even 1% by mass ≤ B2O3 ≤ 7% by mass.

[0034] (SiO2 + B2O3) The total content of SiO2 and B2O3 (SiO2 + B2O3) can affect the physical properties of the glass composition. For example, if the (SiO2 + B2O3) in the glass composition is less than 45% by mass or more than 75% by mass, the devitrification temperature will be high, making it difficult to obtain homogeneous glass. Furthermore, in this case, the melting point of the raw material mixture will be excessively high, making it difficult to maintain a uniform composition of the molten material in the melting furnace when mass-producing the glass composition using a melting furnace. Therefore, it is preferable that the (SiO2 + B2O3) in the glass composition be between 45% by mass and 75% by mass. The lower limit of (SiO2 + B2O3) is, for example, 46% by mass or more, and is preferably 47% by mass or more, 48% by mass or more, 49% by mass or more, 50% by mass or more, 51% by mass or more, or 52% by mass or more. On the other hand, the upper limit of (SiO2 + B2O3) is, for example, 74 mass% or less, and preferably 73 mass% or less, 72 mass% or less, 71 mass% or less, 70 mass% or less, 69 mass% or less, 68 mass% or less, 67 mass% or less, 66 mass% or less, 65 mass% or less, 64 mass% or less, 63 mass% or less, 62 mass% or less, and 61 mass% or less. (SiO2 + B2O3) is, for example, 50 mass% ≤ SiO2 + B2O3 ≤ 65 mass%.

[0035] (Al2O3) Al2O3 is a component that forms the framework of the glass composition. It is also a component that adjusts the devitrification temperature and viscosity during the formation of the glass composition, and is a component that improves the Young's modulus and strength of the glass composition. Furthermore, Al2O3 is a component that improves the water resistance of the glass composition. The Al2O3 content in the glass composition is 14% by mass or more and 21% by mass or less. If the Al2O3 content in the glass composition is less than 14% by mass, the strength and Young's modulus of the glass composition may decrease. On the other hand, if it exceeds 21% by mass, the devitrification temperature becomes high, and it tends to be difficult to obtain homogeneous glass. In this case, the acid resistance and alkali resistance of the glass composition may also decrease. The lower limit of the Al2O3 content is preferably, for example, more than 14% by mass and 14.1% by mass or more. The lower limit of Al2O3 may be 14.5% by mass or more, 15% by mass or more, greater than 15% by mass, 15.1% by mass or more, 15.5% by mass or more, 16% by mass or more, 16.5% by mass or more, or 17% by mass or more. The upper limit of the Al2O3 content is, for example, less than 21% by mass, and preferably 20.5% by mass or less, 20% by mass or less, less than 20% by mass, 19.5% by mass or less, or 19% by mass or less. The upper limit of Al2O3 may be 18.5% by mass or less, 18% by mass or less, 17.5% by mass or less, 17% by mass or less, 16.5% by mass or less, or 16% by mass or less. The Al2O3 content is, for example, 14% by mass ≤ Al2O3 ≤ 20% by mass, and more specifically 14% by mass ≤ Al2O3 ≤ 19.5% by mass.

[0036] (SiO2 + Al2O3) The total content of SiO2 and Al2O3 (SiO2 + Al2O3) can affect the physical properties of the glass composition. For example, if the (SiO2 + Al2O3) in the glass composition is less than 59% by mass or more than 77% by mass, the devitrification temperature will be high, making it difficult to obtain homogeneous glass. Furthermore, in this case, the melting point of the raw material mixture will be excessively high, making it difficult to maintain a uniform composition of the molten material in the melting furnace when mass-producing the glass composition using a melting furnace. Therefore, it is preferable that the (SiO2 + Al2O3) in the glass composition be between 59% by mass and 77% by mass. The lower limit of (SiO2 + Al2O3) is, for example, 60% by mass or more, and is preferably 61% by mass or more, 61.5% by mass or more, 62% by mass or more, 63% by mass or more, 64% by mass or more, 65% by mass or more, or 66% by mass or more. On the other hand, the upper limit of (SiO2 + Al2O3) is, for example, 76% by mass or less, and preferably 75% by mass or less.

[0037] The ratio of the content of Al2O3 to the total content of SiO2 and Al2O3 (SiO2 + Al2O3), Al2O3 / (SiO2 + Al2O3), which is the ratio (by mass) of Al2O3 content to the total content of SiO2 and Al2O3 (SiO2 + Al2O3), can affect the physical properties of the glass composition. For example, if the Al2O3 / (SiO2 + Al2O3) in the glass composition is less than 0.18, the strength and Young's modulus of the glass composition tend to be inferior. On the other hand, if the Al2O3 / (SiO2 + Al2O3) exceeds 0.33, the devitrification temperature becomes high, and it tends to be difficult to obtain a homogeneous glass. Therefore, it is preferable that the Al2O3 / (SiO2 + Al2O3) in the glass composition is between 0.18 and 0.33. The lower limit of Al2O3 / (SiO2 + Al2O3) is, for example, 0.19 or higher, and preferably 0.20 or higher, or 0.21 or higher. On the other hand, the upper limit of Al2O3 / (SiO2 + Al2O3) is, for example, 0.32 or less, and preferably 0.31 or less, or 0.30 or less. For example, Al2O3 / (SiO2 + Al2O3) is 0.19 or more and 0.32 or less.

[0038] (MgO) MgO is a component that adjusts the devitrification temperature and viscosity during the formation of the glass composition, and is also a component that increases the strength and Young's modulus of the glass composition. In addition, MgO is a component that increases the acid resistance of the glass composition. The MgO content in the glass composition is 1% by mass or more and 15% by mass or less. If the MgO content in the glass composition is less than 1% by mass, the devitrification temperature will be high, and it will be difficult to obtain homogeneous glass. In this case, the strength, Young's modulus and acid resistance of the glass composition may also decrease. On the other hand, if it exceeds 15% by mass, the devitrification temperature will be high, and it will be difficult to obtain homogeneous glass. In this case, the alkali resistance of the glass composition may also decrease. The lower limit of the MgO content is, for example, 2% by mass or more, and it is preferable to be 3% by mass or more, 4% by mass or more, or 4.5% by mass or more. The lower limit of the MgO content in the glass composition may be 5% by mass or more, 6% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, or 10% by mass or more. Furthermore, the upper limit of the MgO content is, for example, 14% by mass or less, preferably 13% by mass or less, or 12% by mass or less. The upper limit of the MgO content in the glass composition may also be 11% by mass or less, 10% by mass or less, 9% by mass or less, or 8% by mass or less. The MgO content is, for example, 1% by mass ≤ MgO ≤ 14% by mass, 4% by mass ≤ MgO ≤ 12% by mass, and moreover 4.5% by mass ≤ MgO ≤ 12% by mass.

[0039] (CaO) CaO is a component that adjusts the devitrification temperature and viscosity during the formation of the glass composition, and is also a component that increases the Young's modulus of the glass composition. The CaO content in the glass composition is 1% by mass or more and 21% by mass or less. If the CaO content in the glass composition is less than 1% by mass, the devitrification temperature will be high, and it will be difficult to obtain homogeneous glass. In this case, the Young's modulus of the glass composition may also decrease. On the other hand, if it exceeds 21% by mass, the devitrification temperature will be high, and it will be difficult to obtain homogeneous glass. In this case, the strength of the glass composition may also decrease. The lower limit of the CaO content is preferably, for example, 2% by mass or more, 3% by mass or more, 4% by mass or more, 5% by mass or more, and 5.5% by mass or more. The lower limit of the CaO content in the glass composition may be 6% by mass or more and 7% by mass or more. On the other hand, the upper limit of the CaO content is preferably, for example, 20% by mass or less, 19% by mass or less, 18% by mass or less, and 17% by mass or less. The upper limit of the CaO content in the glass composition may be 16% by mass or less, 15% by mass or less, 14% by mass or less, 13% by mass or less, or 12% by mass or less. For example, the CaO content is 4% by mass ≤ CaO ≤ 21% by mass, 5% by mass ≤ CaO ≤ 18% by mass, and furthermore, 5.5% by mass ≤ CaO ≤ 17% by mass.

[0040] (MgO + CaO) The total content of MgO and CaO (MgO + CaO) can affect the physical properties of the glass composition. The amount of (MgO + CaO) in the glass composition is 5% by mass or more and 22% by mass or less. If the amount of (MgO + CaO) in the glass composition is less than 5% by mass, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the Young's modulus of the glass composition may also decrease. On the other hand, if it exceeds 22% by mass, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the strength of the glass composition may also decrease. The lower limit of (MgO + CaO) is, for example, 6% by mass or more, and it is preferable to have 7% by mass or more, 8% by mass or more, 9% by mass or more, 10% by mass or more, 11% by mass or more, 12% by mass or more, or 13% by mass or more. On the other hand, the upper limit of (MgO + CaO) is, for example, 21.5 mass% or less, preferably 21 mass% or less, or less than 21 mass%. The upper limit of (MgO + CaO) may be 20 mass% or less, and may also be 19 mass% or less, or 18 mass% or less. For example, (MgO + CaO) is 8 mass% ≤ MgO + CaO ≤ 21 mass%, or 12 mass% ≤ MgO + CaO ≤ 22 mass%, and furthermore 12 mass% ≤ MgO + CaO ≤ 21.5 mass%.

[0041] The ratio of the MgO content to the total MgO and CaO content (MgO + CaO), expressed as MgO / (MgO + CaO) on a mass basis, is between 0.05 and 0.88. When MgO / (MgO + CaO) in a glass composition is less than 0.05, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the strength and Young's modulus of the glass composition may also decrease. Furthermore, the acid resistance of the glass composition may decrease. On the other hand, when MgO / (MgO + CaO) exceeds 0.88, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the alkali resistance of the glass composition may also decrease. The lower limit of MgO / (MgO + CaO) is preferably, for example, 0.06 or higher, 0.07 or higher, 0.08 or higher, 0.09 or higher, 0.10 or higher, 0.11 or higher, 0.12 or higher, 0.13 or higher, 0.14 or higher, 0.15 or higher, 0.16 or higher, 0.17 or higher, 0.18 or higher, 0.19 or higher, or 0.20 or higher. The lower limit of MgO / (MgO + CaO) is 0.21 or higher, but it may also be 0.22 or higher, 0.23 or higher, 0.24 or higher, 0.25 or higher, 0.26 or higher, 0.27 or higher, 0.28 or higher, 0.29 or higher, 0.30 or higher, 0.31 or higher, 0.32 or higher, 0.33 or higher, 0.34 or higher, 0.35 or higher, 0.36 or higher, 0.37 or higher, 0.38 or higher, 0.39 or higher, 0.40 or higher, 0.41 or higher, 0.42 or higher, 0.43 or higher, 0.44 or higher, 0.45 or higher, 0.46 or higher, 0.47 or higher, 0.48 or higher, 0.49 or higher, 0.50 or higher, 0.51 or higher, 0.52 or higher, 0.53 or higher, or 0.54 or higher. On the other hand, the upper limit of MgO / (MgO + CaO) is, for example, 0.87 or less, and is preferably 0.86 or less, 0.85 or less, 0.84 or less, 0.83 or less, 0.82 or less, 0.81 or less, 0.80 or less, 0.79 or less, 0.78 or less, 0.77 or less, 0.76 or less, 0.75 or less, 0.74 or less, 0.73 or less, 0.72 or less, 0.71 or less, or 0.70 or less.The upper limit of MgO / (MgO+CaO) is 0.69 or less, and may also be 0.68 or less, 0.67 or less, 0.66 or less, 0.65 or less, 0.64 or less, 0.63 or less, 0.62 or less, 0.61 or less, 0.60 or less, 0.59 or less, 0.58 or less, 0.56 or less, 0.55 or less, 0.54 or less, 0.53 or less, 0.52 or less, 0.51 or less, 0.50 or less, 0.49 or less, 0.48 or less, 0.47 or less, 0.46 or less, 0.45 or less, or 0.44 or less. (MgO / (MgO+CaO)) is, for example, 0.1 to 0.88, 0.18 to 0.80, and furthermore, 0.20 to 0.70.

[0042] (Li₂O, Na₂O, K₂O) Alkali metal oxides (Li₂O, Na₂O, K₂O) lower the melting point of glass compositions and increase the fluidity of the molten material. Therefore, in the mass production of glass compositions using a melting furnace, they have the effect of maintaining a uniform composition of the molten material in the melting furnace. Accordingly, glass compositions can contain an appropriate amount of alkali metal oxides (Li₂O, Na₂O, K₂O). However, if a glass composition contains an excessive amount of alkali metal oxides (Li₂O, Na₂O, K₂O), its Young's modulus and alkali resistance will decrease. In this case, the glass composition will also tend to devitrify.

[0043] The upper limit of the Li₂O content is, for example, 4% by mass or less, and it is preferable that it be 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, 2% by mass or less, less than 2% by mass, 1.5% by mass or less, 1% by mass or less, less than 1% by mass, 0.8% by mass or less, 0.7% by mass or less, 0.6% by mass or less, or 0.5% by mass or less. The Li₂O content may also be 0% by mass ≤ Li₂O ≤ 3% by mass.

[0044] The lower limit of the Na2O content is, for example, 0.1% by mass or more, and may be 0.2% by mass or more, or greater than 0.2% by mass. The upper limit of the Na2O content is, for example, 4% by mass or less, and preferably 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, 2% by mass or less, less than 2% by mass, 1.5% by mass or less, 1% by mass or less, or less than 1% by mass. The upper limit of the Na2O content may be 0.8% by mass or less, 0.7% by mass or less, 0.6% by mass or less, or 0.5% by mass or less. The Na2O content may be 0% by mass ≤ Na2O ≤ 3% by mass.

[0045] The lower limit of the K2O content is, for example, 0.1% by mass or more, and may be 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, or 0.5% by mass or more. The upper limit of the K2O content is, for example, 4% by mass or less, and preferably 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, 2% by mass or less, or less than 2% by mass. The upper limit of the K2O content may be 1.5% by mass or less, 1% by mass or less, or less than 1% by mass. The K2O content may be 0% by mass ≤ K2O ≤ 3% by mass.

[0046] The lower limit of the total content of Na2O and K2O (Na2O + K2O) is, for example, 0.1% by mass or more, and may be 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, 0.5% by mass or more, greater than 0.5% by mass, 0.6% by mass or more, 0.7% by mass or more, greater than 0.7% by mass, 0.8% by mass or more, or greater than 0.8% by mass. The upper limit of (Na2O + K2O) is, for example, 4% by mass or less, and preferably 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, 2% by mass or less, less than 2% by mass, or 1.9% by mass or less. (Na2O + K2O) may be 0% by mass ≤ Na2O + K2O ≤ 3% by mass.

[0047] The total content of alkali metal oxides (Li₂O + Na₂O + K₂O) in the glass composition is 0% by mass or more and 4% by mass or less. The lower limit of (Li₂O + Na₂O + K₂O) is, for example, 0.1% by mass or more, and may be 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, 0.5% by mass or more, greater than 0.5% by mass, 0.6% by mass or more, 0.7% by mass or more, greater than 0.7% by mass, 0.8% by mass or more, or greater than 0.8% by mass. The upper limit of (Li₂O + Na₂O + K₂O) is, for example, 3.5% by mass or less, and preferably 3% by mass or less, 2.5% by mass or less, 2% by mass or less, less than 2% by mass, or 1.9% by mass or less. (Li₂O + Na₂O + K₂O) may satisfy the following conditions: 0 mass% ≤ Li₂O + Na₂O + K₂O ≤ 3.5 mass%, and furthermore, 0 mass% ≤ Li₂O + Na₂O + K₂O ≤ 3 mass%.

[0048] (Fe2O3) Fe2O3 is a component that adjusts the devitrification temperature and viscosity during the formation of glass compositions, and also increases the strength and Young's modulus of the glass composition. The Fe2O3 content in the glass composition is between 1% by mass and 10% by mass. If the Fe2O3 content in the glass composition is 1% by mass or less, the strength and Young's modulus of the glass composition may decrease. Furthermore, in this case, the melting point of the raw material mixture becomes excessively high, making it difficult to maintain a uniform composition of the molten material in the melting furnace when mass-producing glass compositions using a melting furnace. On the other hand, if it exceeds 10% by mass, the devitrification temperature becomes high, making it difficult to obtain homogeneous glass. In this case, the acid resistance and alkali resistance of the glass composition may also decrease. The lower limit of the T-Fe2O3 content in the glass composition is, for example, 1.1% by mass or more, 1.2% by mass or more, 1.3% by mass or more, 1.4% by mass or more, 1.5% by mass or more, 1.6% by mass or more, 1.7% by mass or more, 1.8% by mass or more, and 1.9% by mass or more, and preferably 2% by mass or more, greater than 2% by mass, 2.1% by mass or more, 2.2% by mass or more, 2.3% by mass or more, 2.4% by mass or more, and 2.5% by mass or more. The lower limit of the T-Fe2O3 content may also be 3% by mass or more, 3.5% by mass or more, 4% by mass or more, 4.5% by mass or more, and 5% by mass or more. Furthermore, the upper limit of the T-Fe2O3 content is, for example, 9.5% by mass or less, and preferably 9% by mass or less and 8.5% by mass or less. The upper limit of the T-Fe2O3 content in the glass composition may be 8% by mass or less, 7.5% by mass or less, 7% by mass or less, 6.5% by mass or less, 6% by mass or less, 5.5% by mass or less, 5% by mass or less, 4.5% by mass or less, 4% by mass or less, 3.5% by mass or less, or 3% by mass or less. The T-Fe2O3 content may be, for example, 2% by mass ≤ T-Fe2O3 ≤ 9% by mass, and further, 2% by mass ≤ T-Fe2O3 ≤ 3.5% by mass, 5% by mass ≤ T-Fe2O3 ≤ 9% by mass, or 5% by mass ≤ T-Fe2O3 ≤ 8% by mass.

[0049] (MgO + T-Fe2O3) In the glass composition of this embodiment, the total content of MgO and T-Fe2O3 (MgO + T-Fe2O3) affects the physical properties of the glass composition. For example, if the (MgO + T-Fe2O3) in the glass composition is 2% by mass or less, the strength and Young's modulus of the glass composition may decrease. Furthermore, in this case, the melting point of the raw material mixture becomes excessively high, making it difficult to maintain a uniform composition of the molten material in the melting furnace when mass-producing the glass composition using a melting furnace. On the other hand, if the (MgO + T-Fe2O3) exceeds 25% by mass, the devitrification temperature increases, making it difficult to obtain homogeneous glass. In this case, the alkali resistance of the glass composition may also decrease. Therefore, it is preferable that the (MgO + T-Fe2O3) in the glass composition is greater than 2% by mass and 25% by mass or less. The lower limit of the (MgO + T-Fe2O3) content in the glass composition is, for example, 3% by mass or more, and preferably 4% by mass or more, 5% by mass or more, 6% by mass or more, or 7% by mass or more. The upper limit of the (MgO + T-Fe2O3) content is, for example, 24% by mass or less, and preferably 23% by mass or less, 22% by mass or less, 21% by mass or less, 20% by mass or less, 19% by mass or less, 18% by mass or less, less than 18% by mass, 17.5% by mass or less, or 17% by mass or less.

[0050] In addition to the above components, the glass composition of this embodiment may also contain the following components.

[0051] (P2O5) P2O5, like SiO2 and Al2O3, can form the framework of a glass composition. By including P2O5 in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass production. Therefore, the glass composition may contain P2O5. However, if the glass composition contains an excessive amount of P2O5, its acid resistance and alkali resistance will decrease. In this case, the glass composition will also tend to devitrify or undergo phase separation. The P2O5 content in the glass composition is preferably 0% by mass or more and 10% by mass or less. The upper limit of the P2O5 content is, for example, 8% by mass or less, and it is preferable that it is 6% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, 1.5% by mass or less, 1% by mass or less, or less than 1% by mass. The lower limit of the P2O5 content is, for example, 0.1% by mass or more, and may be 0.2% by mass or more, 0.3% by mass or more, or 0.4% by mass or more. The P2O5 content may be 0% by mass ≤ P2O5 ≤ 8% by mass, 0% by mass ≤ P2O5 ≤ 5% by mass, 0.1% by mass ≤ P2O5 ≤ 1.5% by mass, or 0.1% by mass ≤ P2O5 ≤ 1% by mass. P2O5 may be substantially absent.

[0052] The sum of the content of B2O3, P2O5, Li2O, Na2O, K2O, and T-Fe2O3 (B2O3 + P2O5 + Li2O + Na2O + K2O + T-Fe2O3) can affect the physical properties of the glass composition. For example, if the (B2O3 + P2O5 + Li2O + Na2O + K2O + T-Fe2O3) in the glass composition is 1% by mass or less, the strength and Young's modulus of the glass composition may decrease. Furthermore, in this case, the melting point of the raw material mixture becomes excessively high, making it difficult to maintain a uniform composition of the molten material in the melting furnace when mass-producing the glass composition using a melting furnace. On the other hand, if the amount of (B2O3 + P2O5 + Li2O + Na2O + K2O + T-Fe2O3) exceeds 36% by mass, the devitrification temperature increases, making it difficult to obtain homogeneous glass. In this case, the alkali resistance of the glass composition may also decrease. Therefore, it is preferable that the amount of (B2O3 + P2O5 + Li2O + Na2O + K2O + T-Fe2O3) in the glass composition is greater than 1% by mass and less than or equal to 36% by mass. The lower limit of the content of (B2O3 + P2O5 + Li2O + Na2O + K2O + T-Fe2O3) in the glass composition is, for example, greater than 1.1% by mass, and it is preferable that it is 2% or more by mass, greater than 2.1% by mass, greater than 3% by mass, greater than 3% by mass, greater than 3.1% by mass, and greater than 4% by mass. Furthermore, the upper limit of the content of (B2O3 + P2O5 + Li2O + Na2O + K2O + T-Fe2O3) is, for example, 34% by mass or less, and preferably 32% by mass or less, 30% by mass or less, 28% by mass or less, 26% by mass or less, 24% by mass or less, 22% by mass or less, 20% by mass or less, 19% by mass or less, 18% by mass or less, 17% by mass or less, and 16% by mass or less. The lower limit of (B2O3 + P2O5 + Li2O + Na2O + K2O + T-Fe2O3) is 5% by mass or more, and may be 6% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, 10% by mass or more, 11% by mass or more, 12% by mass or more, and 13% by mass or more. The upper limit for (B2O3 + P2O5 + Li2O + Na2O + K2O + T-Fe2O3) is 15% by mass or less, and may also be 14% by mass or less.

[0053] (SrO) The glass composition may contain SrO. By including SrO in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass manufacturing. On the other hand, if the glass composition contains an excessive amount of SrO, the Young's modulus, acid resistance, and alkali resistance of the glass composition will decrease. Therefore, the upper limit of the SrO content in the glass composition is, for example, 10% by mass or less, and preferably 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, and 0.1% by mass or less. The SrO content may be 0% by mass ≤ SrO ≤ 10% by mass, 0% by mass ≤ SrO ≤ 5% by mass, and further, 0.1% by mass ≤ SrO ≤ 1.5% by mass. SrO may not be substantially present.

[0054] The total content of MgO, CaO, and SrO (MgO + CaO + SrO) can affect the physical properties of the glass composition. For example, if the amount of (MgO + CaO + SrO) in the glass composition is less than 5% by mass, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the Young's modulus of the glass composition may also decrease. On the other hand, if it exceeds 32% by mass, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the strength of the glass composition may also decrease. Therefore, it is preferable that the amount of (MgO + CaO + SrO) in the glass composition is between 5% by mass and 32% by mass. The lower limit of (MgO + CaO + SrO) is, for example, 6% by mass or more, and it is preferable that it is 7% by mass or more, 8% by mass or more, 9% by mass or more, 10% by mass or more, 11% by mass or more, 12% by mass or more, or 13% by mass or more. On the other hand, the upper limit of (MgO + CaO + SrO) is, for example, 30% by mass or less, preferably 28% by mass or less, 26% by mass or less, 25% by mass or less, 24% by mass or less, 23% by mass or less, 22% by mass or less, 21.5% by mass or less, 21% by mass or less, or less than 21% by mass. The upper limit of (MgO + CaO + SrO) is 20% by mass or less, may be 19% by mass or less, or 18% by mass or less.

[0055] (BaO) The glass composition may contain BaO. By including BaO in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass production. On the other hand, if the glass composition contains an excessive amount of BaO, the Young's modulus, acid resistance, and alkali resistance of the glass composition will decrease. Therefore, the upper limit of the BaO content in the glass composition is, for example, 10% by mass or less, and preferably 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, and 0.1% by mass or less. The BaO content may be 0% by mass ≤ BaO ≤ 10% by mass, 0% by mass ≤ BaO ≤ 5% by mass, and further 0.1% by mass ≤ BaO ≤ 1.5% by mass. The BaO content may be substantially absent.

[0056] The total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) can affect the physical properties of the glass composition. For example, if the amount of (MgO + CaO + SrO + BaO) in the glass composition is less than 5% by mass, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the Young's modulus of the glass composition may also decrease. On the other hand, if the amount exceeds 32% by mass, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the strength of the glass composition may also decrease. Therefore, it is preferable that the amount of (MgO + CaO + SrO + BaO) in the glass composition is between 5% by mass and 32% by mass. The lower limit of (MgO + CaO + SrO + BaO) is, for example, 6% by mass or more, and preferably 7% by mass or more, 8% by mass or more, 9% by mass or more, 10% by mass or more, 11% by mass or more, 12% by mass or more, and 13% by mass or more. On the other hand, the upper limit of (MgO + CaO + SrO + BaO) is, for example, 30% by mass or less, and preferably 28% by mass or less, 26% by mass or less, 25% by mass or less, 24% by mass or less, 23% by mass or less, 22% by mass or less, 21.5% by mass or less, 21% by mass or less, and less than 21% by mass. The upper limit of (MgO + CaO + SrO + BaO) is 20% by mass or less, and may also be 19% by mass or less, or 18% by mass or less.

[0057] (ZnO) The glass composition may contain ZnO. By including ZnO in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass manufacturing. On the other hand, if the glass composition contains an excessive amount of ZnO, the Young's modulus, acid resistance, and alkali resistance of the glass composition will decrease. Therefore, the upper limit of the ZnO content in the glass composition is, for example, 10% by mass or less, and preferably 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, and 0.1% by mass or less. The ZnO content may be 0% by mass ≤ ZnO ≤ 10% by mass, 0% by mass ≤ ZnO ≤ 5% by mass, and further, 0.1% by mass ≤ ZnO ≤ 1.5% by mass. ZnO may not be substantially present.

[0058] The total content of MgO, CaO, SrO, BaO, and ZnO (MgO + CaO + SrO + BaO + ZnO) can affect the physical properties of the glass composition. For example, if the amount of (MgO + CaO + SrO + BaO + ZnO) in the glass composition is less than 5% by mass, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the Young's modulus of the glass composition may also decrease. On the other hand, if the amount exceeds 32% by mass, the devitrification temperature tends to be high, making it difficult to obtain homogeneous glass. In this case, the strength of the glass composition may also decrease. Therefore, it is preferable that the amount of (MgO + CaO + SrO + BaO + ZnO) in the glass composition is between 5% by mass and 32% by mass. The lower limit of (MgO + CaO + SrO + BaO + ZnO) is, for example, 6% by mass or more, and preferably 7% by mass or more, 8% by mass or more, 9% by mass or more, 10% by mass or more, 11% by mass or more, 12% by mass or more, and 13% by mass or more. On the other hand, the upper limit of (MgO + CaO + SrO + BaO + ZnO) is, for example, 30% by mass or less, and preferably 28% by mass or less, 26% by mass or less, 25% by mass or less, 24% by mass or less, 23% by mass or less, 22% by mass or less, 21.5% by mass or less, 21% by mass or less, and less than 21% by mass. The upper limit of (MgO + CaO + SrO + BaO + ZnO) is 20% by mass or less, and may also be 19% by mass or less, or 18% by mass or less.

[0059] (TiO2) The glass composition may contain TiO2. By including TiO2 in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass manufacturing. On the other hand, if the glass composition contains an excessive amount of TiO2, it becomes more prone to devitrification. Therefore, the upper limit of the TiO2 content in the glass composition is, for example, 10% by mass or less, and preferably 8% by mass or less, 6% by mass or less, 5% by mass or less, 4.5% by mass or less, 4% by mass or less, 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, 2% by mass or less, less than 2% by mass, 1.8% by mass or less, 1.6% by mass or less, 1.5% by mass or less, 1.4% by mass or less, and 1.3% by mass or less. The lower limit of the TiO2 content is, for example, 0.1% by mass or more, and may be 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, 0.5% by mass or more, and 0.6% by mass or more. The TiO2 content may be 0 mass% ≤ TiO2 ≤ 10 mass%, 0 mass% ≤ TiO2 ≤ 5 mass%, 0.1 mass% ≤ TiO2 ≤ 1.5 mass%, or even 0.1 mass% ≤ TiO2 ≤ 1 mass%. TiO2 may be substantially absent.

[0060] (ZrO2) The glass composition may contain ZrO2. By including ZrO2 in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass production. On the other hand, if the glass composition contains an excessive amount of ZrO2, it becomes more prone to devitrification. Therefore, the upper limit of the ZrO2 content in the glass composition is, for example, 10% by mass or less, and is preferably 9% by mass or less, 8% by mass or less, 7% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, less than 2% by mass, 1% by mass or less, less than 1% by mass, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, or 0.1% by mass or less. The ZrO2 content may be 0% by mass ≤ ZrO2 ≤ 1.5% by mass, and further 0% by mass ≤ ZrO2 ≤ 1% by mass. ZrO2 does not necessarily need to be included.

[0061] (MnO2) The glass composition may contain MnO2. By including MnO2 in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass production. On the other hand, if the glass composition contains an excessive amount of MnO2, it is prone to devitrification. Therefore, the upper limit of the T-MnO2 content in the glass composition is, for example, 5% by mass or less, and is preferably 4% by mass or less, 3% by mass or less, 2% by mass or less, 1.5% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, or 0.1% by mass or less. T-MnO2 may be substantially absent.

[0062] (SnO2) The glass composition may contain SnO2. In particular, in glass compositions with a low alkali metal oxide content, trace amounts of SnO2 can contribute to promoting glass clarity. Furthermore, by including SnO2 in the glass composition, the devitrification temperature and viscosity during melting can be set to a range suitable for glass manufacturing. On the other hand, if the glass composition contains an excessive amount of SnO2, it is prone to devitrification. Therefore, the upper limit of the T-SnO2 content in the glass composition is, for example, 5% by mass or less, and is preferably 4% by mass or less, 3% by mass or less, 2% by mass or less, 1.5% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, 0.2% by mass or less, or 0.1% by mass or less. The T-SnO2 content may be 0% by mass ≤ T-SnO2 ≤ 5% by mass, 0% by mass ≤ T-SnO2 ≤ 3% by mass, or even 0.1% by mass ≤ T-SnO2 ≤ 1.5% by mass. T-SnO2 may be substantially absent.

[0063] (SO3) SO3 is also an optional component. Trace amounts of SO3 can reduce bubbles remaining in the glass and contribute to improving the suitability of the glass for mass production. The lower limit of the SO3 content may be 0.001% by mass or more, and may be 0.002% by mass or more. The upper limit of the SO3 content may be 0.5% by mass or less, 0.2% by mass or less, 0.1% by mass or less, 0.05% by mass or less, 0.04% by mass or less, 0.03% by mass or less, 0.02% by mass or less, and may be 0.01% by mass or less. The SO3 content may be 0% by mass ≤ SO3 ≤ 0.1% by mass, 0% by mass ≤ SO3 ≤ 0.05% by mass, and may be 0% by mass ≤ SO3 ≤ 0.01% by mass. SO3 may not be substantially present.

[0064] (Other components) The glass composition may also contain, as other components, at least one selected from the group consisting of PbO, Bi2O3, HfO2, Ga2O3, La2O3, Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, WO3, Nb2O5, Sc2O3, Y2O3, MoO3, Ta2O5, Cr2O3, CuO, and CoO, each in a content of 0% by mass or more and 5% by mass or less. The permissible content of each of these components may be, for example, less than 2% by mass, and may also be less than 1% by mass, less than 0.5% by mass, less than 0.4% by mass, less than 0.3% by mass, less than 0.2% by mass, or less than 0.1% by mass. The total permissible content of these components may be, for example, 5% by mass or less, and may also be less than 2% by mass, less than 1% by mass, less than 0.5% by mass, less than 0.4% by mass, less than 0.3% by mass, less than 0.2% by mass, or less than 0.1% by mass. However, the other components mentioned above may not be substantially present.

[0065] The glass composition may contain, as an additive, at least one selected from the group consisting of F2, Cl2, Br2, I2, CeO2, As2O3, and Sb2O3, each in a content of 0% by mass or more and 1% by mass or less. The permissible content of each of these components may be, for example, less than 0.5% by mass, less than 0.4% by mass, less than 0.3% by mass, less than 0.2% by mass, and less than 0.1% by mass. The total permissible content of these components may be, for example, 1% by mass or less, less than 0.5% by mass, less than 0.4% by mass, less than 0.3% by mass, less than 0.2% by mass, and less than 0.1% by mass. However, the above additives may not be substantially present.

[0066] Y2O3 and / or La2O3 are components that adjust the devitrification temperature and viscosity during glass formation. Furthermore, Y2O3 and / or La2O3 are components that improve the Young's modulus of the glass. For example, the sum of the content of Y2O3 and La2O3 (Y2O3 + La2O3) may be 5% by mass or less, less than 3% by mass, less than 2% by mass, less than 1% by mass, 0.9% by mass or less, less than 0.5% by mass, or even 0.1% by mass or less. Y2O3 and / or La2O3 may be substantially absent.

[0067] The glass composition may contain at least one element selected from the group consisting of H2O, OH, H2, CO2, CO, He, Ne, Ar, and N2, each in a content of 0% by mass or more and 0.1% by mass or less. The permissible content of each of these elements may be, for example, less than 0.05% by mass, less than 0.03% by mass, and less than 0.01% by mass. The total permissible content of these elements may be, for example, 0.1% by mass or less, less than 0.05% by mass, less than 0.03% by mass, and less than 0.01% by mass. However, each of the above elements may not be substantially present.

[0068] The glass composition may contain trace amounts of precious metal elements. For example, it may contain precious metal elements such as Pt, Rh, Au, and Os in a content of 0% by mass or more and 0.1% by mass or less. The permissible content of each of these components may be, for example, less than 0.1% by mass, less than 0.05% by mass, less than 0.03% by mass, and less than 0.01% by mass. The total permissible content of these components may be, for example, 0.1% by mass or less, less than 0.05% by mass, less than 0.03% by mass, and even less than 0.01% by mass. However, the above-mentioned precious metal elements may not be substantially present.

[0069] An example of the glass composition in this embodiment, expressed in mass%, has the following properties: 50 ≤ SiO2 ≤ 58, 0.1 ≤ B2O3 ≤ 7, 14 ≤ Al2O3 ≤ 19.5, 4.5 ≤ MgO ≤ 12, 5.5 ≤ CaO ≤ 17, 12 ≤ MgO + CaO ≤ 22, 0.1 ≤ Li2O + Na2O + K2O ≤ 3, and 1 < T - Fe2O3 ≤ 9, and the mass ratio calculated by MgO / (MgO + CaO) is 0.20 or more and 0.70 or less. In the above, 1 < T - Fe2O3 ≤ 9 can be substituted with 1 < T - Fe2O3 ≤ 8, 2 ≤ T - Fe2O3 ≤ 3.5, 5 ≤ T - Fe2O3 ≤ 9, or 5 ≤ T - Fe2O3 ≤ 8.

[0070] <Glass Raw Materials> When obtaining the glass composition of this embodiment, there are no restrictions on the raw materials as long as they fall within the composition range described above. Since it contains more than 1% by mass of T-Fe2O3, thermal power plant waste and metal refining waste can also be used as part of the raw materials. Examples of thermal power plant waste include fly ash and clinker ash. Fly ash and clinker ash are suitable as silica alumina sources because they are rich in SiO2 and Al2O3. Coal gasification slag (CGS), which is produced as waste from integrated coal gasification combined cycle (IGCC) power plants, has almost the same chemical composition as fly ash. Therefore, coal gasification slag can also be used as a silica alumina source. Coal gasification slag has the advantage of being easy to handle because it is granular. Examples of metal refining waste include steel slag and copper slag. Examples of steel slag include blast furnace slag, converter slag, and reduction slag. In addition to the examples above, volcanic rocks such as basalt and andesite can also be used as silica alumina sources. In particular, it is preferable to use coal ash as part of the raw materials. In other words, it is preferable to obtain the glass composition by a manufacturing method that includes coal ash as part of the raw materials. However, it is not necessary to use coal ash.

[0071] <Characteristics> The characteristics that the glass composition of this embodiment can have are described below. (Young's modulus) The higher the Young's modulus of the glass composition, the better its elasticity. A glass composition with a high Young's modulus can improve the mechanical properties of composite materials reinforced with glass fibers or glass fillers. Here, Young's modulus (GPA) can be determined by measuring the longitudinal wave velocity and transverse wave velocity of elastic waves propagating through the glass using a conventional ultrasonic method, and from these velocities and the density of the glass measured separately by the Archimedes method. The lower limit of Young's modulus is, for example, 85 GPa or higher, and may be 86 GPa or higher, 87 GPa or higher, 88 GPa or higher, 89 GPa or higher, or 90 GPa or higher. The upper limit of Young's modulus is, for example, 100 GPa or lower, and may be 99 GPa or lower, 98 GPa or lower, 97 GPa or lower, 96 GPa or lower, 95 GPa or lower, or 94 GPa or lower.

[0072] (Glass transition temperature) The glass transition temperature (glass transition point) is an indicator of the heat resistance of glass. The lower limit of the glass transition temperature may be 560°C or higher, 580°C or higher, 600°C or higher, 610°C or higher, 620°C or higher, or even 630°C or higher. The upper limit of the glass transition temperature may be 800°C or lower, 790°C or lower, 780°C or lower, 770°C or lower, or even 760°C or lower.

[0073] (Melting Characteristics) The temperature at which the viscosity of molten glass reaches 1000 dPa·sec (1000 poise) is called the working temperature of the glass, and it is the temperature most suitable for forming glass fibers and glass fillers. When manufacturing flake glass or glass fibers as glass fibers or glass fillers, if the working temperature of the glass is 1000°C or higher, variations in the thickness of the flake glass or the diameter of the glass fibers can be reduced. If the working temperature is 1450°C or lower, and especially 1300°C or lower, fuel costs for melting the glass can be reduced, the glass manufacturing equipment will be less susceptible to thermal corrosion, and the lifespan of the equipment will be extended. The lower limit of the working temperature is, for example, 1000°C or higher, but it may also be 1050°C or higher, or 1100°C or higher. The upper limit of the working temperature is, for example, 1450°C or less, but may also be 1400°C or less, 1350°C or less, 1300°C or less, 1290°C or less, 1280°C or less, 1270°C or less, 1260°C or less, 1250°C or less, 1240°C or less, 1230°C or less, 1220°C or less, 1210°C or less, 1200°C or less, or 1190°C or less.

[0074] The larger the temperature difference ΔT (working temperature minus devitrification temperature), the less likely devitrification is to occur during glass molding, and the higher the yield of homogeneous glass can be produced. In other words, the larger the temperature difference ΔT, the better the moldability. Therefore, the lower limit of ΔT for a glass composition is, for example, -60°C or higher, but may also be -50°C or higher, -40°C or higher, -30°C or higher, -20°C or higher, -10°C or higher, 0°C or higher, 10°C or higher, 20°C or higher, or 30°C or higher. The upper limit of ΔT for a glass composition is, for example, 200°C or lower, but may also be 150°C or lower, or 100°C or lower. Glass compositions with a working temperature of 1300°C or lower and a ΔT of 0°C or higher are particularly suitable for mass production. The devitrification temperature is the temperature at which crystals begin to form and grow in the molten glass substrate.

[0075] The upper limit of the devitrification temperature of the glass composition is, for example, 1400°C or less, but may also be 1350°C or less, 1300°C or less, 1250°C or less, or 1200°C or less. The lower limit of the devitrification temperature is, for example, 1000°C or higher, but may also be 1050°C or higher, or 1100°C or higher.

[0076] (Fracture toughness) As an indicator of strength, fracture toughness K, which will be described later, is used.c is adopted, and this K c indicates that strength tends to be higher as the value is larger. According to a glass composition with high fracture toughness, the mechanical properties of a composite material reinforced by glass fibers or glass fillers can be improved. The fracture toughness K c has a lower limit of, for example, 0.80 Pa·m 1 / 2 or higher, 0.85 Pa·m 1 / 2 or higher, 0.86 Pa·m 1 / 2 or higher, 0.87 Pa·m 1 / 2 or higher, 0.88 Pa·m 1 / 2 or higher, 0.89 Pa·m 1 / 2 or higher, or 0.90 Pa·m 1 / 2 or higher may be satisfied. The fracture toughness K c has an upper limit of, for example, 1.30 Pa·m 1 / 2 or lower, 1.25 Pa·m 1 / 2 or lower, 1.20 Pa·m 1 / 2 or lower, 1.19 Pa·m 1 / 2 or lower, 1.18 Pa·m 1 / 2 or lower, 1.17 Pa·m 1 / 2 or lower, 1.16 Pa·m 1 / 2 or lower, or 1.15 Pa·m 1 / 2 or lower may be satisfied.

[0077] (Chemical durability) As an indicator of acid resistance, the mass reduction rate ΔW1 described later is adopted, indicating that acid resistance is higher as ΔW1 is smaller. When the glass composition is used as a reinforcing material for composite materials or the like, ΔW1 of the glass composition is preferably 1.00 mass% or less. ΔW1 of the glass composition is, for example, 0.90 mass% or less, preferably 0.80 mass% or less, 0.70 mass% or less, 0.60 mass% or less, more preferably 0.50 mass% or less, and even more preferably 0.40 mass% or less. The lower limit of ΔW1 is not particularly limited, and is, for example, 0.01 mass% or more. ΔW1 that can be achieved according to the present embodiment is, for example, 0.01 to 1.00 mass%.

[0078] As an indicator of alkali resistance, the mass loss rate ΔW2, described later, is used, and a smaller ΔW2 indicates higher alkali resistance. When the glass composition is used as a reinforcing material for composite materials, it is preferable that the ΔW2 of the glass composition is 1.00% by mass or less. The ΔW2 of the glass composition is, for example, 0.90% by mass or less, and preferably 0.80% by mass or less, 0.70% by mass or less, 0.60% by mass or less, and even more preferably 0.50% by mass or less. The lower limit of ΔW2 is not particularly limited, and is, for example, 0.02% by mass or more. The ΔW2 that can be achieved by this embodiment is, for example, 0.01 to 1.00% by mass.

[0079] [Glass Fibers] The glass fibers of this embodiment are composed of the glass composition described above. The glass fibers of this embodiment may be long glass fibers or short glass fibers. Short glass fibers are sometimes called glass wool because they have a cotton-like form. The average fiber diameter of the glass fibers is, for example, 0.1 to 50 μm.

[0080] The glass fiber may have at least one shape selected from the group consisting of roving, roving cloth, continuous strand mat, flat fiber, filament mat, yarn, glass cloth, and glass tape.

[0081] Flat fibers have a shape obtained by cutting glass fibers, which have a flattened cross-section such as an ellipse. The major axis D2 of the cross-section of the flat fiber is larger than the minor axis D1, and D2 / D1 is, for example, 1.2 or more. The minor axis D1 is, for example, 0.5 to 25 μm. The major axis D2 is, for example, 0.6 to 300 μm. The length L of the flat fiber is, for example, 10 to 100,000 μm. Flat fibers can be obtained by known methods. The cross-sectional shape of the flat fiber may have a concave shape in which the surface extending along the major axis D2 is recessed in the center compared to the ends.

[0082] The glass fiber manufacturing method of this embodiment includes the steps of melting the glass composition described above and spinning the molten glass composition to form glass fibers. As an example, long glass fibers are manufactured by discharging a glass molten liquid with controlled viscosity from a nozzle and winding it up with a winding machine. These continuous fibers are cut to an appropriate length when in use. Short glass fibers are manufactured by blowing away the glass molten liquid with high-pressure air, centrifugal force, etc.

[0083] [Glass Filler] The glass filler of this embodiment is composed of the glass composition described above. The form of the glass filler is not particularly limited. The glass filler may be at least one selected from, for example, flake glass, chopped strand, milled fiber, glass powder, and glass beads. However, these forms are not strictly distinguishable from each other. The glass filler of this embodiment may be a combination of two or more glass fillers having different forms from each other.

[0084] The method for manufacturing the glass filler in this embodiment includes the steps of melting the glass composition described above and forming the molten glass composition into a glass filler. The various forms of the glass filler will be described below.

[0085] A preferred example of the glass filler in this embodiment is flake glass. Flake glass has a flake-like shape and is also called flake glass. Figures 1A and 1B show an example of flake glass. The average thickness t of the flake glass 1 shown in Figure 1A is, for example, 0.1 to 15 μm. The average particle diameter is, for example, 0.2 to 15000 μm. The aspect ratio of the flake glass 1 is, for example, 2 to 1000. The aspect ratio can be determined by dividing the average particle diameter by the average thickness t.

[0086] The flake-like glass 1 can be manufactured, for example, using the apparatus shown in Figure 2. In the apparatus shown in Figure 2, the glass substrate 11, which has been molten in a refractory kiln tank 12, is inflated into a balloon shape by gas supplied to a blow nozzle 15, forming a hollow glass film 16. Next, the hollow glass film 16 is crushed by a pressure roll 17 to obtain the flake-like glass 1.

[0087] The flake-like glass 1 can also be manufactured, for example, using the apparatus shown in Figure 3. In the apparatus shown in Figure 3, the molten glass substrate 11 poured from the nozzle 21 into the rotating cup 22 flows out radially from the upper edge of the cup 22 due to the centrifugal force generated by the rotation of the rotating cup 22. The flowed-out substrate 11 is sucked in by an airflow through the annular plates 23 arranged above and below, and introduced into an annular cyclone type collector 24. As it passes through the annular plates 23, the glass cools and solidifies as a thin film, and is further broken into minute fragments to obtain the flake-like glass 1.

[0088] Another preferred example of the glass filler in this embodiment is chopped strand. Chopped strand has a shape in which glass fibers are cut into short pieces. The fiber diameter of the chopped strand is, for example, 1 to 50 μm, and its aspect ratio is, for example, 2 to 10000. The aspect ratio of the chopped strand can be determined by dividing the fiber length by the fiber diameter. The cross-section of the chopped strand may be a flattened shape such as an ellipse.

[0089] Chopped strands can be manufactured, for example, using the apparatus shown in Figures 4 and 5. First, as shown in Figure 4, a glass substrate having a predetermined composition, which has been melted in a refractory kiln, is drawn out from a bushing 30 having a large number (e.g., 2400) nozzles at the bottom to form a large number of glass filaments 31. After cooling water is sprayed onto the glass filaments 31, a binder (collating agent) 34 is applied by the application roller 33 of a binder applicator 32. The large number of glass filaments 31 coated with the binder 34 are bundled together by a reinforcing pad 35 to form strands 36, each consisting of, for example, about 800 glass filaments 31. Each strand 36 is wound onto a cylindrical tube 39 fitted into a collet 38 while being traversed by traverse fingers 37. Then, the cylindrical tube 39 on which the strands 36 are wound is removed from the collet 38 to obtain a cake (wound strand body) 40.

[0090] Next, as shown in Figure 5, the cake 40 is placed in the krill 41, the strands 36 are pulled out from the cake 40 and bundled together as a strand bundle 43 using the bundling guide 42. Water or processing liquid is sprayed onto this strand bundle 43 from the spraying device 44. Furthermore, the strand bundle 43 is cut with the rotating blade 46 of the cutting device 45 to obtain chopped strands 47.

[0091] Another preferred example of the glass filler in this embodiment is milled fiber. Milled fiber has the shape of glass fibers cut into a powder. The fiber diameter of milled fiber is, for example, 1 to 50 μm, and its aspect ratio is, for example, 2 to 500. The aspect ratio of milled fiber can be determined by dividing the fiber length by the fiber diameter. Milled fiber can be obtained by known methods. The cross-section of milled fiber may be a flattened shape such as an ellipse.

[0092] Another preferred example of the glass filler in this embodiment is glass powder. Glass powder is glass in powder form and is produced by crushing glass. The average particle size of the glass powder is, for example, 1 to 500 μm. The particle size of the glass powder is defined as the diameter of a sphere with the same volume as the glass powder particles. Glass powder can be obtained by known methods.

[0093] Another preferred example of the glass filler in this embodiment is glass beads. The glass beads have a spherical or substantially spherical shape. The average particle size of the glass beads is, for example, 1 to 500 μm. The particle size of the glass beads is defined as the diameter of a sphere with the same volume as the glass bead particles. The glass beads can be obtained by known methods.

[0094] [Applications of Glass Fibers and Glass Fillers] The glass fibers and glass fillers of this embodiment can be used to reinforce various products. For example, glass fibers and glass fillers may be used to reinforce concrete products, rubber products, or plastic products.

[0095] <Reinforcement of Plastic Products> As described above, glass fibers and glass fillers may be used to reinforce plastic products (resin products). Another aspect of the present invention provides a plastic product comprising at least one selected from the group consisting of glass fibers and glass fillers of this embodiment. In one preferred embodiment, the plastic product comprises a resin composition (matrix resin) and glass fibers or glass fillers embedded in the resin composition. In another preferred embodiment, the plastic product comprises a main body and a covering member covering the surface of the main body, wherein the covering member contains glass fibers or glass fillers. The covering member may further contain a material such as resin. Plastic products reinforced with glass fibers are sometimes called FRP (Fiber Reinforced Plastic).

[0096] The matrix resin may contain a thermosetting resin or a thermoplastic resin. The thermosetting resin is not particularly limited and includes, for example, epoxy resins, modified epoxy resins such as vinyl ester resins, phenolic resins, unsaturated polyester resins, polyimide resins, and bismaleimide resins. The thermoplastic resin is not particularly limited and includes, for example, polyolefin resins, polyamide resins, polycarbonate resins, polyphenylene sulfide resins, and polyetheretherketone resins. Resin products containing thermoplastic resins can be easily manufactured by injection molding, stampable molding, or the like.

[0097] Glass fillers (especially chopped strands) may be used to reinforce plastic products. The glass fibers and glass fillers used to reinforce plastic products may be processed appropriately depending on the type of plastic product. Specifically, fiber sheets containing glass fibers or glass fillers can be used to reinforce plastic products. Glass fibers or glass fillers can also be processed into forms other than chopped strands and fiber sheets. Other forms include those described above for concrete products.

[0098] Plastic products reinforced with glass fibers or glass fillers according to this embodiment can be used in applications such as sports equipment, automobiles and other vehicles, ships, building materials, aircraft, septic tanks, bathtubs, wind turbine blades, lumber, poles, tanks, pipes, sewer pipes (drain pipes), fuel tanks, and home appliances.

[0099] Examples of plastic products used in sporting goods include fishing lines, fishing rods, golf club shafts, skis, canoes, and tennis and badminton rackets and strings. Examples of plastic products used in vehicles include the vehicle body, lamp housings, front and end panels, bumpers, seat housings, and drive shafts. Examples of plastic products used in ships include the ship body, masts, and decks. Examples of plastic products used in aircraft include primary structural materials, secondary structural materials, interior materials, seats, and accessory components. Examples of plastic products used in home appliances include circuit boards, panels, switchgears, insulators, and the main bodies of home appliances.

[0100] In plastic products used in natural environments, such as drainpipes, glass fibers and glass fillers may come into contact with acidic liquids such as acid rain. Therefore, for this application, it is particularly desirable that glass fibers and glass fillers have excellent acid resistance. Glass fibers and glass fillers also need to have a practically sufficient modulus of elasticity.

[0101] <Reinforcement of Concrete Products> As described above, glass fibers and glass fillers may be used to reinforce concrete products. Another aspect of the present invention provides a concrete product comprising at least one selected from the group consisting of glass fibers and glass fillers of this embodiment. In one preferred embodiment, the concrete product comprises a cement composition and glass fibers or glass fillers embedded in the cement composition. In another preferred embodiment, the concrete product comprises a main body and a covering member covering the surface of the main body, wherein the covering member contains glass fibers or glass fillers. The covering member may further contain materials such as resin or cement.

[0102] Glass fillers (especially chopped strands) may be used to reinforce concrete products. The glass fibers and glass fillers used to reinforce concrete products may be processed as appropriate depending on the type of concrete product. Specifically, fiber sheets or rods containing glass fibers or glass fillers can be used to reinforce concrete products.

[0103] (Chopped Strand) Chopped strand can be used, for example, by mixing it with a cement composition. Chopped strand can be classified into "bundled chopped strand" formed from strand bundles and "unbundled chopped strand" formed from a single strand. As an example, a mixture of unbundled chopped strand and a cement composition can be sprayed onto the surface of the main body of a concrete product to form a covering member that covers the surface of the main body. This covering member can prevent the concrete material from peeling off the surface of the main body. On the other hand, a mixture of bundled chopped strand and a cement composition is suitable for reinforcing the entire concrete product. In this mixture, the bundled chopped strand plays a role similar to that of straw used in earthen walls and mortar.

[0104] Chopped strands have a large specific surface area and a large contact area with cement. Therefore, chopped strands used to reinforce concrete products are particularly preferable to have excellent alkali resistance. These chopped strands also need to have a practically sufficient modulus of elasticity.

[0105] (Fiber Sheet) The fiber sheet may be woven or nonwoven. Examples of woven fabrics include cloths using roving or yarn as warp and / or weft threads. Examples of nonwoven fabrics include chopped strand mats formed from chopped strands. Nonwoven fabrics may also be formed from short glass fibers.

[0106] Fiber sheets can be used by impregnating them with a resin such as cement mortar or epoxy resin. Fiber sheets may also be used with their surface covered by a resin layer. In this specification, fiber sheets impregnated with cement mortar or resin, or fiber sheets with their surface covered by a resin layer, may be referred to as protective sheets. Known methods such as hand lay-up molding, SMC (Sheet Molding Compound) molding, and BMC (Bulk Molding Compound) molding can be used to manufacture protective sheets.

[0107] Figures 6A and 6B show an example of a concrete product including the protective sheet described above. More specifically, Figures 6A and 6B show a segment 51 used as a concrete product for lining a tunnel constructed by the shield tunneling method. The segment 51 has an arc-shaped plate and can be joined together in an excavated hole drilled by a shield machine to form a cylindrical lining. More specifically, multiple segments 51 can be joined together in the circumferential direction to form a ring. Multiple segments 51 can be joined together in the axial direction of the ring to form a lining.

[0108] A joint plate 53 is provided on the circumferential joining end face 51A of the segment 51. Multiple segments 51 can be joined in the circumferential direction by fastening and fixing the joint plates 53 to each other. On one joining end face 51B of the segment 51 in the axial direction of the ring, a joining rod (not shown) is provided, protruding from the joining end face 51B. On the other joining end face 51B, a fastener 52 is provided for engaging the joining rod. The fastener 52 has an insertion hole H into which the joining rod is inserted.

[0109] Figure 6B is an enlarged cross-sectional view of the segment 51 near the joint end face 51B. As shown in Figure 6B, the segment 51 further comprises a protective sheet 61 placed on the joint end face 51B. In other words, in the segment 51, the surface of the protective sheet 61 constitutes the joint end face 51B. The protective sheet 61 functions as a covering member that covers the surface of the main body portion of the segment 51. When multiple segments 51 are joined together, these joint end faces 51B, i.e., the protective sheets 61, come into contact with each other.

[0110] As shown in Figures 6A and 6B, the segment 51 may further include a sealing member 64 for sealing the segments 51 when multiple segments 51 are joined together.

[0111] In the shield tunneling method, the shield machine excavates the ground with its tip cutter while extending the jack rods with the jack spreaders in contact with the lining made up of segments 51. This allows the shield machine to receive a reaction force from the lining through the jacks, and to be propelled by this reaction force. Since the shield machine is equipped with multiple jacks, multiple spreaders are in contact with the lining. Therefore, if the pressing force from the multiple spreaders acts outward on the lining, stress may be generated between two adjacent segments 51 in the lining. The protective sheet 61 can buffer this stress, thereby suppressing the occurrence of cracks near the joint end face 51B.

[0112] (Rod) A rod is made by bundling glass fibers together, for example. For example, a rod can be made by braiding glass fibers into a cord. In a rod, the bundled glass fibers may be hardened with cement or a resin such as epoxy resin. A rod can be used, for example, as a substitute for reinforcing bars.

[0113] Figure 7 shows an example of a concrete product including the rods described above. More specifically, Figure 7 shows a utility pole 70 as the concrete product. Part of the utility pole 70 is embedded in the ground 80 and extends upward. The utility pole 70 comprises a cement composition 72 containing mortar or the like, which is filled inside, and a plurality of rods 75 embedded in the cement composition 72. The rods 75 are arranged parallel to each other from the bottom of the utility pole 70 along the direction in which the utility pole 70 extends. In the rods 75 used to reinforce the utility pole 70, it is particularly preferable that the glass fibers have an excellent modulus of elasticity. These glass fibers also need to have sufficient alkali resistance for practical purposes.

[0114] The utility pole 70 shown in Figure 7 can be manufactured, for example, by inserting a rod 75 into a utility pole with a hollow interior through an opening or the like, and then filling the inside of the utility pole with a cement composition 72. Details of this manufacturing method are described, for example, in Japanese Patent Publication No. 2006-2543. In Japanese Patent Publication No. 2006-2543, an aramid rod made of aramid fibers is used. The rod 75 containing glass fibers in this embodiment tends to have superior alkali resistance compared to an aramid rod.

[0115] (Other) Examples of concrete products reinforced with glass fibers or glass fillers are not limited to those described above. Glass fibers and glass fillers can be used as aggregates, reinforcements, etc., in various concrete products. Because glass fibers and glass fillers tend to have good mechanical properties and thermal stability, they can also be used in concrete products where heat resistance is required (e.g., concrete products used in power plants, melting furnaces, coke ovens, etc.) or in building materials where fire resistance is required (e.g., fire-resistant structures of buildings, fire-resistant coatings, etc.).

[0116] Furthermore, glass fibers and glass fillers can also be processed into forms other than the chopped strands, fiber sheets, and rods described above, such as strands, rovings, yarns, and cords. Yarn is obtained by twisting one or more strands together.

[0117] Furthermore, the glass fibers and glass fillers of this embodiment can also be used as high-temperature insulating materials in vehicle mufflers, engine parts, blast furnaces, etc. The glass fibers and glass fillers of this embodiment can also be used as separators in batteries such as lead-acid batteries.

[0118] As described above, this embodiment provides the following technology: (First technology) A glass composition in which, expressed in mass%, 45 ≤ SiO2 ≤ 65, 1 ≤ B2O3 ≤ 10, 14 ≤ Al2O3 ≤ 21, 1 ≤ MgO ≤ 15, 2 ≤ CaO ≤ 21, 5 ≤ MgO + CaO ≤ 22, 0.1 ≤ Li2O + Na2O + K2O ≤ 3, 1 < T - Fe2O3 ≤ 10, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.88 or less.

[0119] (Second technology) A glass composition expressed in mass%, where 45 ≤ SiO2 ≤ 65, 0.1 ≤ B2O3 ≤ 8, 14 ≤ Al2O3 ≤ 21, 1 ≤ MgO ≤ 15, 4 ≤ CaO ≤ 21, 5 ≤ MgO + CaO ≤ 22, 0 ≤ Li2O + Na2O + K2O ≤ 4, 1 < T-Fe2O3 ≤ 10, and substantially no T-MnO2 is contained, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.79 or less.

[0120] (Third technology) A glass composition in which, expressed in mass%, 45 ≤ SiO2 ≤ 65, 0 ≤ B2O3 ≤ 10, 14 ≤ Al2O3 ≤ 19, 2 ≤ MgO ≤ 15, 3 ≤ CaO ≤ 20, 5 ≤ MgO + CaO ≤ 22, 0 ≤ BaO ≤ 10, 0 ≤ Li2O + Na2O + K2O ≤ 3, 0 ≤ TiO2 ≤ 5, 1 < T - Fe2O3 ≤ 9, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.83 or less.

[0121] (Fourth technology) A glass composition according to any one of technologies 1 to 3, wherein the SiO2 content, expressed in mass%, is 48 ≤ SiO2 ≤ 64.

[0122] (Fifth Technology) A glass composition according to any one of Technologies 1 to 4, wherein the SiO2 and B2O3 content, expressed in mass%, is 50 ≤ SiO2 + B2O3 ≤ 65.

[0123] (Sixth technology) A glass composition according to any one of technologies 1 to 5, wherein the mass ratio calculated by Al2O3 / (SiO2 + Al2O3) is 0.18 or more and 0.33 or less.

[0124] (Technology 7) A glass composition according to any one of Technologies 1 to 6, wherein the P2O5 content, expressed in mass%, is 0 ≤ P2O5 ≤ 5.

[0125] (Technology 8) A glass composition according to any one of Technologies 1 to 7, wherein the MgO and CaO content, expressed in mass%, is 8 ≤ MgO + CaO ≤ 21.

[0126] (Technology 9) A glass composition according to any one of Technologies 1 to 8, wherein the SrO content, expressed in mass%, is 0 ≤ SrO ≤ 10.

[0127] (Technology 10) A glass composition according to any one of Technologies 1 to 9, wherein the BaO content, expressed in mass%, is 0 ≤ BaO ≤ 10.

[0128] (Technology No. 11) A glass composition according to any one of Technologies 1 to 10, wherein the content of Na2O and K2O, expressed in mass%, is 0.1 ≤ Na2O + K2O ≤ 3.

[0129] (Technology 12) A glass composition according to any one of Technologies 1 to 11, wherein the TiO2 content, expressed in mass%, is 0 ≤ TiO2 ≤ 5.

[0130] (Technology 13) A glass composition according to any one of Technologies 1 to 12, wherein the ZrO2 content, expressed in mass%, is 0 ≤ ZrO2 ≤ 10.

[0131] (Technology 14) A glass composition according to any one of Technologies 1 to 13, which is substantially free of T-SnO2.

[0132] (Technology 15) A glass composition according to any one of Technologies 1 to 14, which is substantially free of T-MnO2.

[0133] (Technology 16) A glass fiber composed of one of the glass compositions from Technology 1 to 15.

[0134] (Technology No. 17) Glass fiber of Technology No. 16, used for reinforcing plastic products or concrete products.

[0135] (Technology No. 18) A glass filler comprising one of the glass compositions of technologies 1 to 15.

[0136] (Technology No. 19) A glass filler of Technology No. 18, used for reinforcing plastic products or concrete products.

[0137] (Technology 20) A glass filler of Technology 18 or 19, which is at least one selected from the group consisting of flake glass, chopped strand, milled fiber, glass powder, and glass beads.

[0138] (Technology 21) A flaky glass filler, one of technologies 18 to 20.

[0139] (Technology 22) A chopped strand glass filler, one of technologies 18 to 20.

[0140] (Technology 23) A milled fiber, a glass filler from any one of technologies 18 to 20.

[0141] (Technology No. 24) A method for producing glass fibers, comprising the steps of: melting one of the glass compositions from technologies 1 to 15; and spinning the melted glass composition to form glass fibers.

[0142] (Technology No. 25) A method for producing Technology No. 24, wherein coal ash is used as part of the raw materials for the glass composition.

[0143] (Technology No. 26) A method for manufacturing a glass filler, comprising the steps of: melting one of the glass compositions from technologies 1 to 15; and forming the molten glass composition into a glass filler.

[0144] (Technology No. 27) A method for producing Technology No. 26, wherein coal ash is used as part of the raw materials for the glass composition.

[0145] The present invention will be described in more detail below with reference to examples and comparative examples.

[0146] [Examples 1-86 and Comparative Examples 1-21] Raw materials for general glass compositions, such as silicon dioxide, were weighed to achieve the compositions shown in Tables 2-16 (the unit of component content is mass%), and mixed to a homogeneous state to prepare raw material mixed batches. In particular, in Examples 1-73 and Comparative Examples 1-21, silicon dioxide, diboron trioxide, aluminum oxide, phosphoric acid, magnesium oxide, calcium carbonate, strontium carbonate, zinc oxide, lithium carbonate, sodium carbonate, potassium carbonate, titanium dioxide, zirconium oxide, diiron trioxide, manganese dioxide, and calcium fluoride were used. In Examples 74-86, coal ash, silicon dioxide, diboron trioxide, aluminum oxide, phosphoric acid, magnesium oxide, calcium carbonate, strontium carbonate, zinc oxide, lithium carbonate, sodium carbonate, potassium carbonate, titanium dioxide, zirconium oxide, and diiron trioxide were used. The composition of the coal ash used is shown in Table 1.

[0147]

[0148] Next, the prepared raw material mixture batch was melted in an electric furnace at 1500-1600°C and maintained in a molten state for approximately 4 hours to ensure uniform composition. Subsequently, a portion of the resulting molten glass composition (molten glass) was poured onto an iron plate and slowly cooled to room temperature in the electric furnace to obtain a bulk glass composition sample (plate-shaped) for evaluation.

[0149] For the prepared glass composition sample (hereinafter referred to as "sample"), the Young's modulus E, working temperature, devitrification temperature, and fracture toughness K were determined. c The mass loss rate ΔW1 under acidic solution and the mass loss rate ΔW2 under alkaline solution were measured. The measurement method is as follows.

[0150] <Measurement of Young's Modulus> A 25 × 25 × 5 mm plate-shaped sample was prepared by cutting the sample and mirror-polishing each surface. The density ρ of the sample was measured using the Archimedes method. Young's modulus was measured according to the ultrasonic pulse method of JIS R1602-1995. Specifically, using the sample used for the density measurement described above, the sound velocity of the ultrasonic pulse propagating was measured for both longitudinal and transverse waves. This was substituted along with the density data into the following formula to calculate Young's modulus. The propagation velocity was calculated using an ultrasonic thickness gauge MODEL 25DL PLUS manufactured by Olympus Corporation. The time it took for a 20 kHz ultrasonic pulse to propagate in the thickness direction of the sample, reflect back, and return was divided by the propagation distance (twice the thickness of the sample). E = 3ρ・v t 2 ・(v l 2 -4 / 3・v t 2 ) / (v l 2 -v t 2 E: Young's modulus (GPa) ρ: Density (kg / m³) 3 ) v l : Longitudinal wave velocity (m / s) v t : Transverse wave velocity (m / s)

[0151] <Measurement of Glass Transition Temperature> The average linear thermal expansion coefficient of the obtained glass composition was measured using a commercially available dilatometer [Rigaku Corporation, Thermomechanical Analyzer, TMA8310], and the glass transition temperature was obtained based on the thermal expansion curve obtained from the TMA device.

[0152] <Measurement of Working Temperature> The relationship between viscosity and temperature was investigated for the obtained glass composition using the standard platinum ball pulling method, and the working temperature was determined from the results. The platinum ball pulling method is a method of measuring viscosity by immersing a platinum ball in molten glass and applying the relationship between the load (resistance) applied when the platinum ball is pulled up at a constant velocity, and the gravitational force and buoyancy acting on the platinum ball, to Stokes' law, which describes the relationship between viscosity and falling velocity when minute particles settle in a fluid.

[0153] <Measurement of Devitrification Temperature> The prepared glass composition was crushed, and glass particles that passed through a 1.0 mm standard sieve specified in JIS Z8801 but not through a 2.8 mm standard sieve were separated. This glass was placed in a platinum boat and heated for 2 hours in an electric furnace with a temperature gradient (900 to 1400°C). The devitrification temperature of the glass composition was determined from the highest temperature in the electric furnace corresponding to the location where crystals appeared in the furnace. Note that the temperature distribution in the electric furnace (different temperatures depending on the location) was measured in advance, and the glass composition placed in a predetermined location in the electric furnace was heated at the temperature of that predetermined location, which was measured in advance. The temperature difference ΔT is the temperature difference obtained by subtracting the devitrification temperature from the working temperature. Considering the manufacturing process of glass fibers and glass fillers, it is desirable that the devitrification temperature of the glass composition be lower than the working temperature.

[0154] <Toughness of destruction K c Measurement of fracture toughness K > The sample was cut, and each surface was mirror-polished to prepare a 25 x 25 x 5 mm plate-shaped sample. The fracture toughness K was then measured in accordance with the Japanese Industrial Standard "Test Method for Room Temperature Fracture Toughness of Fine Ceramics" (JIS R1607-2015). c The fracture toughness K was measured. Specifically, the diagonal length of the indentation left by an indenter pressed into the sample surface with the largest possible indentation load and the crack length were measured, and these values, along with the Young's modulus mentioned above, were substituted into the following formula to determine the fracture toughness K. c The fracture toughness K was calculated. c For the measurement, a Mitutoyo Corporation MVK-G2 micro-Vickers hardness tester was used. An indenter was pressed into the test surface with an indentation load of 19610 mN for 15 seconds, and the diagonal length of the indentation and the crack length were measured using the microscope attached to the tester. The indenter was pressed into the sample surface at least five times. K c = 0.026 * (E 1 / 2 P 1 / 2 a) / C 3 / 2 K c Fracture toughness (Pa·m) 1 / 2 E: Young's modulus (Pa) P: Indentation load (N) C: Half of the average crack length (m) a: Half of the average diagonal length of the indentation (m)

[0155] <Measurement of Mass Loss Rates ΔW1 and ΔW2> The mass loss rates ΔW1 and ΔW2 were measured in accordance with the standard "Method for Measuring the Chemical Durability of Optical Glass (Powder Method)" (JOGIS 06) established by the Japan Optical Glass Manufacturers Association.

[0156] (Measurement of Mass Loss Rate ΔW1 under Acidic Solution) The measurement is performed according to the following procedure: 1. Grind the glass composition sample. 2. Separate the powder sample from the ground sample that passes through a 600 μm test sieve but remains in a 425 μm test sieve. The test sieves are those specified in JIS Z8801. 3. Weigh 5 g of the separated powder sample. 4. Immerse the weighed powder sample in 80 mL of 21.2 mass% sulfuric acid aqueous solution at 99°C for 1 hour. 5. After immersion, remove the supernatant by decantation, dry the residual sample, and measure its mass. 6. Calculate the mass loss rate ΔW1 as the ratio of the difference between the mass of the sample and the mass of the residual sample to the mass of the sample before immersion in the sulfuric acid aqueous solution. As mentioned above, ΔW1 is an indicator of acid resistance.

[0157] (Measurement of Mass Loss Rate ΔW2 under Alkaline Solution) The measurement is performed according to the following procedure: 1. Grind the glass composition sample. 2. Separate the powder sample from the ground sample that passes through a 600 μm test sieve but remains in a 425 μm test sieve. The test sieves are those specified in JIS Z8801. 3. Weigh 5 g of the separated powder sample. 4. Immerse the weighed powder sample in 80 mL of 10% by mass sodium hydroxide aqueous solution at 99°C for 1 hour. 5. After immersion, remove the supernatant by decantation, dry the residual sample, and measure its mass. 6. Calculate the mass loss rate ΔW2 as the ratio of the difference between the mass of the sample and the mass of the residual sample to the mass of the sample before immersion in the sodium hydroxide aqueous solution. As mentioned above, ΔW2 is an indicator of alkali resistance.

[0158] Young's modulus, glass transition temperature, devitrification temperature, working temperature, temperature difference ΔT, and fracture toughness K of the glass composition. c Tables 2 to 16 show the mass loss rate ΔW1 under acidic solution and the mass loss rate ΔW2 under alkaline solution.

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[0174] As can be seen from Tables 2 to 12, the glass compositions of Examples 1 to 86 had a Young's modulus in the range of 89 to 95 GPa, an operating temperature in the range of 1145 to 1280°C, and a ΔT in the range of -49 to 85°C. A ΔT of 0°C or higher was obtained from each of the examples except for Examples 74 and 75. Furthermore, the glass compositions of Examples 1 to 86 had a glass transition temperature in the range of 632 to 736°C and fracture toughness K c 0.90–1.16 MPa·m 1 / 2 The range was as follows. Thus, the glass compositions of the examples had low viscosity, high elastic modulus and strength, and improved moldability.

[0175] As can be seen from Tables 13 to 16, the glass compositions of Comparative Examples 1 to 21 all met at least one of the following conditions: Young's modulus of 88 GPa or less (Comparative Examples 2 to 4, 6, 10, 11, 18, 20), working temperature of 1290°C or higher (Comparative Examples 2, 10, 17, 21), and ΔT of less than -70°C (Comparative Examples 1, 5 to 9, 12 to 19).

[0176] Comparative Example 16 corresponds to the composition of conventional basalt fibers. Comparative Example 17 is Example 1 of Patent Document 2. Comparative Example 18 is Example 3 of Patent Document 1. Comparative Example 19 is Example 10 of Patent Document 3. Comparative Example 20 corresponds to E-glass. Comparative Example 21 corresponds to S-glass.

[0177] The glass composition of the present invention has a low working temperature, high elastic modulus, and improved moldability, making it useful not only as a glass fiber but also as a filler for flake glass, chopped strands, milled fibers, glass powder, glass beads, etc. Due to its high elasticity and high strength, it is particularly useful for reinforcing plastic or concrete products.

Claims

1. A glass composition in which, expressed in mass%, 45 ≤ SiO2 ≤ 65, 1 ≤ B2O3 ≤ 10, 14 ≤ Al2O3 ≤ 21, 1 ≤ MgO ≤ 15, 2 ≤ CaO ≤ 21, 5 ≤ MgO + CaO ≤ 22, 0.1 ≤ Li2O + Na2O + K2O ≤ 3, and 1 < T - Fe2O3 ≤ 10, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.88 or less.

2. A glass composition expressed in mass%, where 45 ≤ SiO2 ≤ 65, 0.1 ≤ B2O3 ≤ 8, 14 ≤ Al2O3 ≤ 21, 1 ≤ MgO ≤ 15, 4 ≤ CaO ≤ 21, 5 ≤ MgO + CaO ≤ 22, 0 ≤ Li2O + Na2O + K2O ≤ 4, and 1 < T-Fe2O3 ≤ 10, and substantially no T-MnO2 is contained, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.79 or less.

3. A glass composition in which, expressed in mass%, 45 ≤ SiO2 ≤ 65, 0 ≤ B2O3 ≤ 10, 14 ≤ Al2O3 ≤ 19, 2 ≤ MgO ≤ 15, 3 ≤ CaO ≤ 20, 5 ≤ MgO + CaO ≤ 22, 0 ≤ BaO ≤ 10, 0 ≤ Li2O + Na2O + K2O ≤ 3, 0 ≤ TiO2 ≤ 5, 1 < T - Fe2O3 ≤ 9, and the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.83 or less.

4. The glass composition according to any one of claims 1 to 3, wherein the SiO2 content, expressed in mass%, is 48 ≤ SiO2 ≤ 64.

5. The glass composition according to any one of claims 1 to 3, wherein the content of SiO2 and B2O3, expressed in mass%, is 50 ≤ SiO2 + B2O3 ≤ 65.

6. The glass composition according to any one of claims 1 to 3, wherein the mass ratio calculated by Al2O3 / (SiO2 + Al2O3) is 0.18 or more and 0.33 or less.

7. The glass composition according to any one of claims 1 to 3, wherein the P2O5 content, expressed in mass%, is 0 ≤ P2O5 ≤ 5.

8. The glass composition according to any one of claims 1 to 3, wherein the content of MgO and CaO, expressed in mass%, is 8 ≤ MgO + CaO ≤ 21.

9. The glass composition according to any one of claims 1 to 3, wherein the SrO content, expressed in mass%, is 0 ≤ SrO ≤ 10.

10. The glass composition according to claim 1 or 2, wherein the BaO content, expressed in mass%, is 0 ≤ BaO ≤ 10.

11. The glass composition according to any one of claims 1 to 3, wherein the content of Na2O and K2O, expressed in mass%, is 0.1 ≤ Na2O + K2O ≤ 3.

12. The glass composition according to claim 1 or 2, wherein the TiO2 content, expressed in mass%, is 0 ≤ TiO2 ≤ 5.

13. The glass composition according to any one of claims 1 to 3, wherein the ZrO2 content, expressed in mass%, is 0 ≤ ZrO2 ≤ 10.

14. A glass composition according to any one of claims 1 to 3, which is substantially free of T-SnO2.

15. The glass composition according to claim 1 or 3, which is substantially free of T-MnO2.

16. Glass fiber comprising the glass composition according to any one of claims 1 to 3.

17. The glass fiber according to claim 16, used for reinforcing plastic products or concrete products.

18. A glass filler comprising the glass composition according to any one of claims 1 to 3.

19. The glass filler according to claim 18, which is used for reinforcing plastic products or concrete products.

20. The glass filler according to claim 18, which is at least one selected from the group consisting of flake glass, chopped strand, milled fiber, glass powder, and glass beads.

21. The glass filler according to claim 18, wherein it is a flake-like glass.

22. The glass filler according to claim 18, which is a chopped strand.

23. The glass filler according to claim 18, wherein it is a milled fiber.

24. A method for producing glass fibers, comprising the steps of: melting a glass composition according to any one of claims 1 to 3; and spinning the molten glass composition to form glass fibers.

25. The manufacturing method according to claim 24, wherein coal ash is used as part of the raw materials for the glass composition.

26. A method for producing a glass filler, comprising the steps of: melting a glass composition according to any one of claims 1 to 3; and forming the molten glass composition into a glass filler.

27. The manufacturing method according to claim 26, wherein coal ash is used as part of the raw materials of the glass composition.

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