Reinforcement material for rubber composite material and production method therefor

Abstract

Provided is a reinforcement material for a rubber composite material, said reinforcement material including a glass composition containing the components of, 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, wherein the mass ratio calculated from MgO / (MgO+CaO) is 0.05-0.88 inclusive.

Description

Reinforcement material for rubber composites and method for manufacturing the same

[0001] The present invention relates to a reinforcing material containing a glass composition suitable for use in rubber composites, and more specifically, to a reinforcing material having the shape of glass fibers or other shapes suitable for use in rubber composites, and to a method for producing the same.

[0002] Rubber products are reinforced using rubber reinforcing cords, which consist of strands made of bundled glass fibers. These cords are embedded in rubber products such as rubber belts and tires to suppress elongation and strength reduction, contributing to improved dimensional stability and extended fatigue life of the rubber products.

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] Patent Document 1 discloses glass fibers used in rubber reinforcing cords.

[0009] International Publication No. 2006 / 057405

[0010] Yamane, Masayuki et al. (eds.), "Glass Engineering Handbook (Popular Edition)," 1st edition, Asakura Shoten Co., Ltd., 1999, 514 pages.

[0011] With the expanding applications of rubber composite materials, there is a need for reinforcing materials suitable for mass production. Therefore, the present invention aims to provide a new reinforcing material that is suitable for use in rubber composite materials and is also suitable for mass production.

[0012] The present invention provides a reinforcing material for rubber composites, comprising a glass composition containing the following components, 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, wherein the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.88 or less.

[0013] From another aspect, the present invention provides a reinforcing material for rubber composites, comprising a glass composition containing the following components, expressed in mass%, 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, substantially free of T-MnO2, and having a mass ratio of MgO / (MgO + CaO) of 0.05 or more and 0.79 or less.

[0014] The present invention also provides a reinforcing material for rubber composites, comprising a glass composition containing the following components, 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, and 1 < T - Fe2O3 ≤ 9, wherein the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.83 or less.

[0015] Furthermore, the present invention provides a method for manufacturing a reinforcing material for rubber composite materials, comprising the steps of: melting a glass composition that corresponds to at least one selected from the group consisting of a), b), and c); and molding the molten glass composition into at least one selected from the group consisting of glass fibers and glass fillers, wherein coal ash is used as part of the raw materials for the glass composition. a) A glass composition that contains the following components, 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. b) A glass composition containing the following components, expressed in mass%, with 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, substantially free of T-MnO2, and having a mass ratio of 0.05 or more and 0.79 or less calculated by MgO / (MgO + CaO). c) A glass composition containing the following components, expressed in mass%, with values ​​of 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, wherein the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.83 or less.

[0016] According to the present invention, a new reinforcing material is provided that is suitable for use in rubber composite materials, has a high modulus of elasticity, and is suitable for mass production.

[0017] This figure shows an example of the structure of a rubber belt including a rubber reinforcing cord.

[0018] Embodiments of the present invention will be described below, but the following description is not intended to limit the present invention to any particular embodiment. In this specification, "substantially absent," "substantially absent," and "substantially absent" all mean that the content is less than 0.1% by mass, less than 0.05% by mass, less than 0.01% by mass, even less than 0.005% by mass, especially less than 0.003% by mass, and in some cases less than 0.001% by mass. "Substantially" means that the presence of trace amounts of impurities originating from glass raw materials, manufacturing equipment, molding equipment, etc. "Main component" means the component with the largest content by mass. "T-Fe2O3" means total iron oxide converted to iron trioxide (Fe2O3). Also, "T-MnO2" means total manganese oxide converted to manganese dioxide (MnO2). Furthermore, "T-SnO2" means total tin oxide converted to tin dioxide (SnO2). "Alkali metal oxides" refer to lithium oxide (Li₂O), sodium oxide (Na₂O), and potassium oxide (K₂O). The upper and lower limits of the content described below can be combined arbitrarily. Furthermore, the content of each component can be combined arbitrarily to form the glass composition.

[0019] Below, we will first describe the details of the glass composition that makes up the reinforcing material.

[0020] <Components of the glass composition> One embodiment of the glass composition of the present invention contains the following components, expressed in mass%, with the following properties: 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.

[0021] Furthermore, in another aspect of the present invention, a glass composition expressed in mass% contains the following components: 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.

[0022] Furthermore, in another aspect of the present invention, a glass composition expressed in mass% contains the following components: 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.

[0023] Hereinafter, each component of the glass composition will be described in detail.

[0024] (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.

[0025] (B₂O₃) Like SiO₂ and Al₂O₃, B₂O₃ can form the skeleton of a glass composition. By including B₂O₃ in the glass composition, the devitrification temperature and viscosity during melting can be adjusted to a range suitable for glass production. Therefore, the glass composition may optionally contain B₂O₃. However, excessive content of B₂O₃ in the glass composition reduces acid resistance and alkali resistance. In addition, in this case, the Young's modulus of the glass composition tends to decrease. The content of B₂O₃ 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 is preferably 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. Further, the upper limit of the B₂O₃ content is, for example, 9% by mass or less, and is 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 be substantially not contained. The B₂O₃ content may satisfy 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, or further 1% by mass ≦ B₂O₃ ≦ 7% by mass.

[0026] (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%.

[0027] (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.

[0028] (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.

[0029] 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.

[0030] (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.

[0031] (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.

[0032] (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%.

[0033] 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.

[0034] (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 the glass composition contains an excessive amount of alkali metal oxides (Li₂O, Na₂O, K₂O), the Young's modulus and alkali resistance will decrease. In this case, the glass composition will also tend to devitrify.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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%.

[0040] (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.

[0041] (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.

[0042] In addition to the above components, the glass composition of this embodiment may also contain the following components.

[0043] (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.

[0044] 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.

[0045] (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.

[0046] 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.

[0047] (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.

[0048] 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.

[0049] (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.

[0050] 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.

[0051] (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.

[0052] (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.

[0053] (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.

[0054] (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.

[0055] (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.

[0056] (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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] <Glass Raw Materials> When obtaining the glass composition of this form, 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 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.

[0063] <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 forming the reinforcing material, the better the elasticity, and the better the mechanical properties of the rubber composite material reinforced by the reinforcing material, including glass fiber reinforced rubber. 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 this Young's modulus may be 85 GPa or higher, 86 GPa or higher, 87 GPa or higher, 88 GPa or higher, 89 GPa or higher, and even 90 GPa or higher. The upper limit of Young's modulus is preferably 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, and even 94 GPa or lower.

[0064] (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.

[0065] (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 shaping the glass. When manufacturing reinforcing materials such as glass fibers, if the working temperature of the glass is 1000°C or higher, variations in the shape of the reinforcing material, such as the diameter of the glass fibers, can be reduced. If the working temperature is 1450°C or lower, 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 can be 1000°C or higher, 1050°C or higher, and even 1100°C or higher. The upper limit of the working temperature may be 1450°C or lower, and may also be 1400°C or lower, 1350°C or lower, 1300°C or lower, 1290°C or lower, 1280°C or lower, 1270°C or lower, 1260°C or lower, 1250°C or lower, 1240°C or lower, 1230°C or lower, 1220°C or lower, 1210°C or lower, 1200°C or lower, and even 1190°C or lower.

[0066] 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. ΔT can be -60°C or higher, and can 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, and even 30°C or higher. On the other hand, if ΔT is 200°C or lower, it becomes easier to adjust the glass composition. ΔT can be 200°C or lower, 150°C or lower, and even 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.

[0067] The upper limit of the devitrification temperature of glass can be, for example, 1400°C or less, 1350°C or less, 1300°C or less, 1250°C or less, or 1200°C or less. The lower limit of the devitrification temperature can be, for example, 1000°C or more, 1050°C or more, or 1100°C or more.

[0068] Among glass fibers, long glass fibers are produced, for example, by drawing molten glass base material from nozzles of a bushing provided at the bottom of a furnace tank, continuously winding it with a winder, and spinning it into a fibrous form. Short glass fibers are produced, for example, by flowing molten glass base material into a spinner rotated at a high speed from the bottom of the furnace tank, and further drawing and thinning fibrous glass ejected from holes provided on the side surface of the spinner by centrifugal force using pressure such as a gas jet. Flaky glass is also produced from molten glass by methods called the blowing method, the cup method, and the like. The same applies to powdered glass. Considering these production processes, it is desirable for a glass composition to have excellent meltability and good moldability, appropriate temperature-viscosity characteristics, and a devitrification temperature that is not higher than the working temperature.

[0069] (Fracture Toughness) For a reinforcing material, the fracture toughness K of the glass composition forming the reinforcing material c tends to be higher in strength as it increases, which improves the mechanical properties of rubber composites reinforced with reinforcing materials, including glass fiber-reinforced rubber. The fracture toughness K c may have 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, 0.90 Pa·m 1 / 2 or higher. The fracture toughness K c may have 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, 1.15 Pa·m 1 / 2 or lower.

[0070] (Chemical Durability) Acid resistance and alkali resistance are appropriate indicators of chemical durability for reinforcement applications of rubber composites. The mass loss rate ΔW1, described later, is used as an indicator of acid resistance, and a smaller ΔW1 indicates higher acid resistance. When glass fibers or other reinforcing materials are used to reinforce rubber, the ΔW1 of the reinforcing material is preferably 1.00% by mass or less. Therefore, the ΔW1 of the glass composition may be 1.00% by mass or less, 0.90% by mass or less, 0.80% by mass or less, 0.70% by mass or less, 0.60% by mass or less, and even 0.50% by mass or less, or 0.40% by mass or less. The lower limit of ΔW1 is not particularly limited, and is, for example, 0.01% by mass or more. The ΔW1 that can be achieved by this embodiment is, for example, 0.01 to 1.00% by mass.

[0071] As an indicator of alkali resistance, the mass loss rate ΔW2, described later, is used, and a smaller ΔW2 indicates higher alkali resistance. When glass fibers or other reinforcing materials are used to reinforce rubber, the ΔW2 of the reinforcing material is preferably 1.00% by mass or less. The ΔW2 of the glass composition may be 1.00% by mass or less, 0.90% by mass or less, 0.80% by mass or less, 0.70% by mass or less, 0.60% by mass or less, and even 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.

[0072] Reinforcement materials made of glass with such excellent chemical durability can be suitably used in glass fiber reinforced rubber and the like.

[0073] <Reinforcement Material> The shape of the reinforcement material is not particularly limited, but for example, it may be glass fiber, glass filler, or at least one selected from the group consisting of glass fiber, flake glass, and powdered glass.

[0074] [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. Long glass fibers are manufactured by flowing a glass melt 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 melt with high-pressure air, centrifugal force, etc. 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.

[0075] The average fiber diameter of glass fibers is, for example, 0.1 to 50 μm. The average fiber diameter of glass fibers may be 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, or even 0.5 μm or more, and may be 50 μm or less, 40 μm or less, 30 μm or less, or 25 μm or less. In the case of glass long fibers, the average fiber diameter may be 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, or even 5 μm or more. In the case of glass short fibers, the average fiber diameter may be 10 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, or even 1 μm or less.

[0076] The glass fiber may have at least one shape selected from the group consisting of, for example, roving, roving cloth, continuous strand mat, flat fiber, filament mat, yarn, glass cloth, and glass tape.

[0077] 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.

[0078] [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.

[0079] Flake-like glass has a flake-like shape and is also called flake glass. The average thickness of flake-like glass is, for example, 0.1 to 15 μm. The thickness of flake-like glass corresponds to the distance t between the two main surfaces of the flake-like glass. The average particle diameter of flake-like glass is, for example, 0.2 to 15000 μm. The aspect ratio of flake-like glass is, for example, 2 to 1000. The aspect ratio can be determined by dividing the average particle diameter by the average thickness. Flake-like glass can be obtained by known methods such as the blow method and the cup method.

[0080] Chopped strands have the shape of glass fibers that have been cut into short pieces. The fiber diameter of chopped strands is, for example, 1 to 50 μm, and their aspect ratio is, for example, 2 to 10000. The aspect ratio of chopped strands can be determined by dividing the fiber length by the fiber diameter. The cross-section of chopped strands may be a flattened shape such as an ellipse.

[0081] Milled fibers have a shape obtained by cutting glass fibers into a powder. The fiber diameter of milled fibers is, for example, 1 to 50 μm, and the aspect ratio is, for example, 2 to 500. The aspect ratio of milled fibers can be determined by dividing the fiber length by the fiber diameter. Milled fibers can be obtained by known methods. The cross-section of milled fibers may be a flattened shape such as an ellipse.

[0082] Glass powder is glass in powder form and is produced by crushing glass. The average particle size of glass powder is, for example, 1 to 500 μm. The particle size of 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.

[0083] Glass beads have a spherical or nearly spherical shape. The average particle size of glass beads is, for example, 1 to 500 μm. The particle size of glass beads is defined as the diameter of a sphere with the same volume as the glass bead particles. Glass beads can be obtained by known methods.

[0084] <Rubber Composite Material> The rubber composite material of this embodiment includes a rubber composition (matrix rubber) and a reinforcing material containing the glass composition described above, more specifically a reinforcing material having the shape of glass fibers, glass fillers, etc. That is, the rubber composite material of this embodiment is reinforced by the reinforcing material. The rubber composite material may be, for example, glass fiber reinforced rubber (FRR).

[0085] Glass fibers and glass fillers used to reinforce rubber products may be processed as appropriate depending on the type of rubber product. Specifically, cords containing glass fibers can be used to reinforce rubber products.

[0086] (Cord) The cord (rubber-reinforced cord) comprises strands formed by bundling the above-mentioned glass fibers (rubber-reinforced fibers). The number of glass fibers contained in the strand is not particularly limited, for example, 100 to 2000, typically 200 to 600. The strand can be formed by bundling a predetermined number of spun glass fibers with a sizing agent commonly used for strand formation, such as an elastomer-based sizing agent, when spinning glass fibers. The formed strand may be wound onto a collet or the like and subjected to predetermined treatments such as drying.

[0087] In a cord, it is preferable that multiple strands are bundled together to form a strand aggregate. However, the cord may consist of only one strand. The strand or strand aggregate preferably contains 200 to 36,000 glass fibers, and more preferably 200 to 7,800 glass fibers. The wire diameter of the strand or strand aggregate is preferably 10 tex to 8,350 tex, and more preferably 68 tex to 1,430 tex.

[0088] In the cord, the strands may be coated with a first coating layer formed from a treatment solution A containing at least one selected from resorcinol-formaldehyde condensate and a vulcanizing agent, and latex. By coating the strands with the first coating layer, the adhesion between the cord and the matrix rubber in which the cord is embedded can be improved. The first coating layer may cover a single strand, or it may cover a strand assembly in which two or more strands are bundled together.

[0089] The type of latex is not particularly limited, but may be at least one selected from, for example, vinylpyridine-styrene-butadiene terpolymer (VP) latex, chlorosulfonated polystyrene (CSM) latex, acrylonitrile-butadiene copolymer (NBR) latex, and nitrile group-containing highly saturated polymer latex. By using these materials, the heat resistance and water resistance of the reinforcing cord can be improved. Examples of nitrile group-containing highly saturated polymers include materials that are hydrogenated copolymers or terpolymers containing acrylonitrile as a constituent unit, such as hydrogenated NBR (H-NBR), or materials that contain acrylonitrile and saturated hydrocarbons as constituent units, such as butadiene-ethylene-acrylonitrile terpolymer.

[0090] The resorcinol-formaldehyde condensate (RF) is not particularly limited, and may be a novolac type, resol type, or a mixture thereof. The molar ratio of resorcinol (R) to formaldehyde (F) in the RF is preferably R:F = 1:1 to 3. RF is generally sold commercially as a liquid containing solids, but those with a solids content in the range of 5% to 10% by weight are preferably used.

[0091] The vulcanizing agent is not particularly limited and, for example, at least one selected from maleimide compounds and organic diisocyanate compounds. When the treatment solution A contains a vulcanizing agent, the content of the vulcanizing agent in the treatment solution A may be in the range of 5 to 100 parts by weight, preferably in the range of 20 to 75 parts by weight, per 100 parts by weight of the solids content of the latex. In this case, a better balance can be achieved between the flexibility of the cord and its adhesion to the matrix rubber.

[0092] The organic diisocyanate compound is not particularly limited, but examples include hexamethylene diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl isocyanate), toluene diisocyanate, xylene diisocyanate, naphthalene diisocyanate, and methylenebis(phenyl isocyanate).

[0093] Treatment solution A may contain one or more types of these organic diisocyanate compounds, and in the case of substances that have isomers with respect to substituents, such as toluene diisocyanate and methylenebis(phenyl isocyanate), it may be a mixture of these isomers. Furthermore, the organic diisocyanate compounds may be used in a state in which their isocyanate groups are protected with phenols or lactams.

[0094] The maleimide compound is not particularly limited, but for example, bismaleimide, phenylmaleimide, and diphenylmethane-4,4'-bismaleimide may be used.

[0095] The solid content in processing solution A is preferably in the range of 10% to 40% by weight, and more preferably in the range of 25% to 35% by weight. If the content is too low, the formation of the first coating layer will be insufficient, and if it is too high, it will be difficult to control the amount of processing solution A applied to the strand, and the thickness of the first coating layer will likely become uneven.

[0096] Treatment solution A may contain bases, such as ammonia, to adjust the pH as needed, and may also contain stabilizers, anti-aging agents, etc. Treatment solution A may also contain fillers such as carbon black, in which case a cord with superior adhesion to the matrix rubber can be formed.

[0097] The formation of the first coating layer on the strand can be achieved by applying methods commonly used in cord production. For example, the strand (including the aggregate) can be continuously immersed in a coating bath containing treatment solution A, and after removing the strand from the coating bath, excess treatment solution can be removed and, if necessary, dried. The strand with the first coating layer formed on it can be used as a cord as is, or, if necessary, various processes such as twisting and the formation of a second coating layer, as described later, may be applied.

[0098] The first coating layer should be formed in an amount equivalent to approximately 10% to 30% by weight of the strand.

[0099] The cord may have a structure in which two or more strands, each covered with a first covering layer and then twisted, are bundled together and further twisted. In this case, the strength is further improved and the cord can have superior bending fatigue resistance. The number of twists may be about 0.5 to 4 times, preferably about 1.2 to 3 times, per 2.54 cm (1 inch) in the length direction. The yarn formed by the twisting may be bundled together in groups of 2 to 20 strands, preferably about 6 to 15 strands, and then twisted again in the length direction 0.5 to 4 times, preferably about 1 to 2.8 times, per 2.54 cm.

[0100] The cord may be covered with a second coating layer containing rubber. In this case, the cord can have improved adhesion to the matrix rubber.

[0101] The type of rubber is not particularly limited and can be appropriately selected depending on the type of matrix rubber, etc. For example, if the matrix rubber is a nitrile group-containing highly saturated polymer, it is preferable that the second coating layer contains CSM as the rubber because it has superior adhesion. Also, for example, if the matrix rubber is a mixed rubber in which polyzinc methacrylate (ZDMA) is dispersed in a nitrile group-containing highly saturated polymer, it is preferable that the second coating layer contains a nitrile group-containing highly saturated copolymer or a mixed rubber with the same composition as the matrix rubber as the rubber because it has superior adhesion.

[0102] The second coating layer may be formed, for example, by impregnating strands (including aggregates), strands (including aggregates) coated with the first coating layer, or yarns in which strands have been further twisted, into a treatment solution B in which rubber or a rubber precursor is dissolved, and then drying. Since CSM and nitrile group-containing highly saturated polymers dissolve in aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated hydrocarbons such as trichloroethylene, ketones such as methyl ethyl ketone, and esters such as ethyl acetate, the treatment solution B may contain these organic substances as a solvent.

[0103] Treatment solution B may contain a vulcanizing agent. As a vulcanizing agent, in addition to the maleimide compounds and organic diisocyanate compounds mentioned above, sulfur; organic peroxides such as dicumyl peroxide and 1,3-bis(t-butylperoxy-m-isopropyl)benzene; aromatic nitroso compounds such as p-dinitronaphthalene and p-dinitrosobenzene may be used. Treatment solution B may also contain inorganic fillers, antioxidants, vulcanizing aids, plasticizers, etc., as needed.

[0104] The content of substances other than the solvent (rubber, vulcanizing agent, etc.) in processing solution B can be appropriately set depending on the type of substance, but a second coating layer can be easily formed if it is in the range of about 3% to 25% by weight, preferably 5% to 15% by weight. The content of rubber or rubber precursor in the substances other than the solvent is preferably about 20% to 60% by weight, and if processing solution B contains a vulcanizing agent, the content of the vulcanizing agent in the substances other than the solvent is preferably in the range of about 0.5% to 30% by weight.

[0105] When forming the second coating layer, for example, the treatment solution B may be applied to the surface of the strand (including the aggregate) or the twisted yarn in an amount of 1% to 15% by weight, preferably 2% to 6% by weight, relative to the weight of the strand, in terms of the amount of substances other than the solvent.

[0106] Examples of rubber products reinforced with the above-mentioned cord include rubber belts, rubber tires, and rubber hoses. An example of a rubber belt is a power transmission belt. Examples of power transmission belts include interlocking belts and friction belts. An example of an interlocking belt is a toothed belt, such as a timing belt for automobiles. Examples of friction belts include flat belts, round belts, V-belts, and V-ribbed belts. Rubber tires are typically automobile tires or bicycle tires. In cords used to reinforce rubber products, it is particularly preferable that the glass fibers have an excellent modulus of elasticity.

[0107] Figure 1 shows an example of the structure of a rubber belt including cords. The rubber belt 91 has the shape of a so-called toothed belt and comprises a matrix rubber 93 and a plurality of cords 92 embedded in the matrix rubber 93. The cords 92 are arranged parallel to each other along the longitudinal direction of the rubber belt 91, in other words, in a direction perpendicular to the belt width direction through which the protruding portions 94, which form the "teeth," traverse. Tooth cloth 95 is attached to the surface of the rubber belt 91 on which the protruding portions 94 are formed, for purposes such as suppressing wear.

[0108] (Other) Glass fibers or glass fillers can also be processed and used in forms other than the codes described above.

[0109] As described above, this embodiment provides the following technology. (First technology) A reinforcing material for rubber composites, comprising a glass composition containing the following components, 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 having a mass ratio of 0.05 or more and 0.88 or less calculated by MgO / (MgO + CaO).

[0110] (Second technology) A reinforcing material for rubber composites, comprising a glass composition containing the following components, expressed in mass%, 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, substantially free of T-MnO2, and having a mass ratio of MgO / (MgO + CaO) of 0.05 or more and 0.79 or less.

[0111] (Third technology) A reinforcing material for rubber composites, comprising a glass composition containing the following components, 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 having a mass ratio of 0.05 or more and 0.83 or less calculated by MgO / (MgO + CaO).

[0112] (Fourth technology) A reinforcing material according to any one of technologies 1 to 3, wherein the glass composition contains components such that 48 ≤ SiO2 ≤ 64, expressed in mass percent.

[0113] (Fifth Technology) A reinforcing material according to any one of technologies 1 to 4, wherein the glass composition contains components such that, expressed in mass%, 50 ≤ SiO2 + B2O3 ≤ 65.

[0114] (Sixth technology) A reinforcing material according to any one of technologies 1 to 5, wherein the glass composition has a mass ratio of 0.18 or more and 0.33 or less calculated by Al2O3 / (SiO2 + Al2O3).

[0115] (Seventh Technology) A reinforcing material according to any one of technologies 1 to 6, wherein the glass composition contains components such that 0 ≤ P2O5 ≤ 5, expressed in mass percent.

[0116] (Technology 8) A reinforcing material according to any one of Technologies 1 to 7, wherein the glass composition contains components such that 8 ≤ MgO + CaO ≤ 21, expressed in mass percent.

[0117] (Technology 9) A reinforcing material according to any one of Technologies 1 to 8, wherein the glass composition contains components such that 0 ≤ SrO ≤ 10, expressed in mass percent.

[0118] (Technology 10) A reinforcing material according to any one of Technologies 1 to 9, wherein the glass composition contains components such that 0 ≤ BaO ≤ 10, expressed in mass percent.

[0119] (Technology 11) A reinforcing material according to any one of Technologies 1 to 10, wherein the glass composition contains components such that 0.1 ≤ Na₂O + K₂O ≤ 3, expressed in mass percent.

[0120] (Technology 12) A reinforcing material according to any one of Technologies 1 to 11, wherein the glass composition contains components such that 0 ≤ TiO2 ≤ 5, expressed in mass percent.

[0121] (Technology 13) A reinforcing material according to any one of Technologies 1 to 12, wherein the glass composition contains components such that 0 ≤ ZrO2 ≤ 10, expressed in mass percent.

[0122] (Technology 14) A reinforcing material according to any one of Technologies 1 to 13, wherein the glass composition substantially does not contain T-SnO2.

[0123] (Technology 15) A reinforcing material according to any one of Technologies 1 to 14, wherein the glass composition substantially does not contain T-MnO2.

[0124] (Technology 16) A reinforcing material according to any one of technologies 1 to 15, wherein the reinforcing material is at least one selected from the group consisting of glass fibers and glass fillers.

[0125] (Technology 17) The reinforcing material of Technology 16, wherein the glass fiber is at least one selected from the group consisting of roving, roving cloth, continuous strand mat, flat fiber, filament mat, chopped strand, yarn, glass cloth, and glass tape.

[0126] (Technology 18) The reinforcing material of Technology 16 or 17, wherein the glass filler is at least one selected from flake glass, chopped strand, milled fiber, glass powder, and glass beads.

[0127] (Technology No. 19) A rubber composite material containing one of the reinforcing materials from technologies No. 1 to No. 18.

[0128] (Technology No. 20) A method for manufacturing a reinforcing material for rubber composites, comprising the steps of: melting a glass composition specified in any one of Technologies 1 to 15; and molding the molten glass composition into at least one selected from the group consisting of glass fibers and glass fillers, wherein coal ash is used as part of the raw materials for the glass composition.

[0129] The present invention will be described in more detail below with reference to examples and comparative examples.

[0130] [Examples 1-84 and Comparative Examples 1-17] Raw materials for general glass compositions, such as silicon dioxide, were weighed to achieve the compositions shown in Tables 2-15 (the unit of content of each component is mass%), and mixed to a homogeneous state to prepare raw material mixed batches. In particular, in Examples 1-73 and Comparative Examples 1-17, 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 74-84, 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.

[0131]

[0132] 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.

[0133] 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.

[0134] <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)

[0135] <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.

[0136] <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.

[0137] <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.

[0138] <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)

[0139] <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.

[0140] (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.

[0141] (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.

[0142] 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 15 show the mass loss rate ΔW1 under acidic solution and the mass loss rate ΔW2 under alkaline solution.

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[0157] As can be seen from Tables 2 to 12, the glass compositions of Examples 1 to 84 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 0 to 85°C. Furthermore, the glass compositions of Examples 1 to 84 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.

[0158] As can be seen from Tables 13 to 15, the glass compositions of Comparative Examples 1 to 17 all met at least one of the following criteria: Young's modulus of 88 GPa or less (Comparative Examples 2 to 4, 6, 10, 11, 16), working temperature of 1290°C or higher (Comparative Examples 2, 10, 17), and ΔT of less than -70°C (Comparative Examples 1, 5 to 9, 12 to 15). Comparative Example 16 corresponds to E glass, and Comparative Example 17 corresponds to S glass.

Claims

1. A reinforcing material for rubber composites, comprising a glass composition containing the following components, expressed in mass%, with values ​​of 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, wherein the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.88 or less.

2. A reinforcing material for rubber composites, comprising a glass composition containing the following components, expressed in mass%, 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, substantially free of T-MnO2, and having a mass ratio of MgO / (MgO + CaO) of 0.05 or more and 0.79 or less.

3. A reinforcing material for rubber composites, comprising a glass composition containing the following components, 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, and 1 < T - Fe2O3 ≤ 9, wherein the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.83 or less.

4. The reinforcing material according to any one of claims 1 to 3, wherein the glass composition contains components such that, expressed in mass%, 48 ≤ SiO2 ≤ 64.

5. The reinforcing material according to any one of claims 1 to 3, wherein the glass composition contains components such that, expressed in mass%, 50 ≤ SiO2 + B2O3 ≤ 65.

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

7. The reinforcing material according to any one of claims 1 to 3, wherein the glass composition contains components such that 0 ≤ P2O5 ≤ 5, expressed in mass percent.

8. The reinforcing material according to any one of claims 1 to 3, wherein the glass composition contains components such that, expressed in mass%, 8 ≤ MgO + CaO ≤ 21.

9. The reinforcing material according to any one of claims 1 to 3, wherein the glass composition contains components such that 0 ≤ SrO ≤ 10, expressed in mass percent.

10. The reinforcing material according to claim 1 or 2, wherein the glass composition contains components such that 0 ≤ BaO ≤ 10, expressed in mass percent.

11. The reinforcing material according to any one of claims 1 to 3, wherein the glass composition contains components such that 0.1 ≤ Na₂O + K₂O ≤ 3, expressed in mass percent.

12. The reinforcing material according to claim 1 or 2, wherein the glass composition contains components such that 0 ≤ TiO2 ≤ 5, expressed in mass percent.

13. The reinforcing material according to any one of claims 1 to 3, wherein the glass composition contains components such that 0 ≤ ZrO2 ≤ 10, expressed in mass percent.

14. The reinforcing material according to any one of claims 1 to 3, wherein the glass composition substantially does not contain T-SnO2.

15. The reinforcing material according to claim 1 or 3, wherein the glass composition substantially does not contain T-MnO2.

16. The reinforcing material according to any one of claims 1 to 3, wherein the reinforcing material is at least one selected from the group consisting of glass fibers and glass fillers.

17. The reinforcing material according to claim 16, wherein the glass fiber is at least one selected from the group consisting of roving, roving cloth, continuous strand mat, flat fiber, filament mat, chopped strand, yarn, glass cloth, and glass tape.

18. The reinforcing material according to claim 16, wherein the glass filler is at least one selected from flake glass, chopped strand, milled fiber, glass powder, and glass beads.

19. A rubber composite material comprising a reinforcing material according to any one of claims 1 to 3.

20. A method for manufacturing a reinforcing material for rubber composites, comprising the steps of: melting a glass composition that corresponds to at least one selected from the group consisting of a), b), and c); and molding the molten glass composition into at least one selected from the group consisting of glass fibers and glass fillers, wherein coal ash is used as part of the raw materials for the glass composition. a) A glass composition containing the following components, 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 having a mass ratio of 0.05 or more and 0.88 or less calculated by MgO / (MgO + CaO). b) A glass composition containing the following components, expressed in mass%, with 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, substantially free of T-MnO2, and having a mass ratio of 0.05 or more and 0.79 or less calculated by MgO / (MgO + CaO). c) A glass composition containing the following components, expressed in mass%, with values ​​of 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, wherein the mass ratio calculated by MgO / (MgO + CaO) is 0.05 or more and 0.83 or less.

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