Glass fibers

Abstract

The present disclosure provides novel glass fibers which are suitable for mass production, while being suitable for use as a thermal insulation material and / or a sound absorbing material. The present disclosure provides glass fibers which contain a glass composition that contains, in mass%, 50 ≤ SiO2 ≤ 75, 0 ≤ B2O3 ≤ 4, 5 ≤ Al2O3 ≤ 15, 5 ≤ CaO ≤ 30 and 0 ≤ (Li2O + Na2O + K2O) ≤ 20, or alternatively a glass composition that contains, in mass%, 50 ≤ SiO2 ≤ 75, 0 ≤ B2O3 ≤ 4, 0.1 ≤ (MgO + CaO) ≤ 20, 9 ≤ (Li2O + Na2O + K2O) ≤ 20 and 5 ≤ ZrO2 ≤ 20.

Description

Glass fiber

[0001] The present invention relates to glass fibers suitable for use as thermal and / or acoustic insulation.

[0002] Glass wool is an aggregate of short glass fibers made by fiberizing glass into a flocculent form, and because it contains many air spaces inside, it has excellent heat insulating and sound absorbing properties and is used as a heat insulating and sound absorbing material for buildings, vehicles, etc. Glass wool is also non-flammable and is used as a non-combustible material. Patent Document 1 discloses that soda lime glass and A-glass are preferred as glass fibers for such glass wool.

[0003] JP 2016-141248 A

[0004] So-called flat glass compositions, such as soda-lime glass and A-glass, have insufficient water resistance, which gradually reduces the thermal and sound-insulating properties of glass fibers. C-glass compositions are known as glass compositions with excellent chemical durability. However, C-glass compositions contain approximately 4 to 6 mass% diboron trioxide (BO). BO tends to scatter during melting of glass raw materials and corrodes the furnace walls of melting furnaces and regenerative furnaces. Therefore, glass compositions containing BO at these levels can affect the lifespan of the equipment used to manufacture them. Therefore, an object of the present invention is to provide a new glass fiber suitable for use as a thermal insulating and / or sound-absorbing material and also suitable for mass production.

[0005] The present invention provides a glass fiber for use in a thermal insulation material and / or a sound absorption material, the glass fiber comprising a glass composition containing, expressed in mass%, the following components: 50≦SiO2≦75, 0≦B2O3≦4, 5≦Al2O3≦15, 5≦CaO≦30, 0≦(Li2O+Na2O+K2O)≦20.

[0006] In another aspect, the present invention provides a glass fiber for use in a thermal insulation material and / or a sound absorption material, the glass fiber comprising a glass composition containing, expressed in mass%, the following components: 50≦SiO2≦75, 0≦B2O3≦4, 0.1≦(MgO+CaO)≦20, 9≦(Li2O+Na2O+K2O)≦20, and 5≦ZrO2≦20.

[0007] The present invention provides a new glass fiber that is suitable for use in thermal and / or acoustic insulation materials and is also suitable for mass production.

[0008] The following describes embodiments of the present invention, but the following description is not intended to limit the present invention to any particular embodiment. In this specification, "substantially free" and "substantially free" mean a content of less than 0.1 mass%, less than 0.05 mass%, less than 0.01 mass%, even less than 0.005 mass%, particularly less than 0.003 mass%, and in some cases less than 0.001 mass%. "Substantially" allows for the inclusion of trace amounts of impurities derived from glass raw materials, manufacturing equipment, molding equipment, etc. "Major component" refers to the component with the highest content by mass. "T-Fe2O3" refers to total iron oxide converted to diiron trioxide (Fe2O3). "Alkali metal oxide" refers to lithium oxide (Li2O), sodium oxide (Na2O), and potassium oxide (KO). The upper and lower limits of the content described below can be combined arbitrarily.

[0009] In particular, "glass fiber for heat insulating material and / or sound absorbing material" means "glass fiber used as at least one selected from the group consisting of heat insulating material and sound absorbing material."

[0010] <Components of Glass Composition> (Glass Composition A) One example of a glass composition (hereinafter referred to as glass composition A) contains, in mass %, the following components: 50≦SiO2≦75, 0≦B2O3≦4, 5≦Al2O3≦15, 5≦CaO≦30, 0≦(Li2O+Na2O+K2O)≦20.

[0011] The silicon dioxide (SiO2) content in glass composition A may be 55% by mass or more and 72% by mass or less. The aluminum oxide (Al2O3) content may be 5% by mass or more and 14% by mass or less. The calcium oxide (CaO) content may be 5% by mass or more and 28% by mass or less. The diboron trioxide (BO3) content may be 0.1% by mass or more and 4% by mass or less. Glass composition A may be a composition that is substantially free of BO3. The total content of alkali metal oxides (Li2O + Na2O + KO) may be 0.1% by mass or more and 20% by mass or less. Glass composition A may be a composition that is substantially free of alkali metal oxides. Glass composition A may not necessarily contain substantially any components other than the above-mentioned components.

[0012] (Specific Examples of Glass Composition A) As more specific examples of glass composition A, compositions A-1 to A-4 are given below.

[0013] (Composition A-1) Composition A-1 contains the following components expressed in mass %: 50≦SiO2≦67, 0≦B2O3<2, 5≦Al2O3≦15, 45≦(SiO2-Al2O3)≦57, 1≦MgO≦10, 10≦CaO≦30, 0≦(Li2O+Na2O+K2O)≦12, 0≦T-Fe2O3≦5

[0014] The glass composition having the glass composition A-1 has excellent heat resistance, is suppressed from being deformed when heated to a high temperature, and has excellent chemical durability.

[0015] Each component in glass composition A-1 is described below. (SiO2) SiO2 is a component that forms the glass skeleton and is the main component of composition A-1. SiO2 also adjusts the devitrification temperature and viscosity during glass formation and improves acid resistance. The SiO2 content is 50% by mass or more and 67% by mass or less, particularly 55% by mass or more and 65% by mass or less. The lower limit of the SiO2 content can be 56% by mass or more, 57% by mass or more, 58% by mass or more, 59% by mass or more, or even more than 60% by mass. The upper limit of the SiO2 content can be 64% by mass or less, or 63% by mass or less.

[0016] (B2O3) B2O3 is a component that forms the skeleton of glass. B2O3 is also a component that adjusts the devitrification temperature and viscosity during glass formation. The lower limit of the B2O3 content may be 0.1 mass% or more. The upper limit of the B2O3 content may be less than 2 mass%, or may be 1.5 mass% or less, 1 mass% or less, or 0.5 mass% or less. The upper limit of the B2O3 content may be 0.1 mass% or less. Composition A-1 may be substantially free of B2O3.

[0017] (Al2O3) Al2O3 is a component that forms the skeleton of glass. It also adjusts the devitrification temperature and viscosity during glass formation and improves the water resistance of glass. Furthermore, Al2O3 improves the Young's modulus and heat resistance of glass. On the other hand, excessive Al2O3 content reduces the acid resistance of glass. An Al2O3 content of 5% by mass or more and 15% by mass or less suppresses the increase in the devitrification temperature of glass that would make glass production difficult, and enhances the acid resistance of glass. Furthermore, the melting point of glass does not become excessively high, improving uniformity during melting of raw materials. The lower limit of the Al2O3 content can be 6% by mass or more, 7% by mass or more, 8% by mass or more, 8.5% by mass or more, 9% by mass or more, 9.5% by mass or more, 10% by mass or more, 10.5% by mass or more, 11% by mass or more, or even 11.1% by mass or more. The upper limit of the Al2O3 content may be 14 mass% or less, 13 mass% or less, 12.5 mass% or less, less than 12 mass%, or even 11.9 mass% or less.

[0018] (SiO2-Al2O3) From the viewpoint of improving the acid resistance of glass, the lower limit of the value obtained by subtracting the Al2O3 content from the SiO2 content (SiO2-Al2O3) may be 45% by mass or more, 47% by mass or more, more than 48% by mass, 48.5% by mass or more, more than 49% by mass, or even 49.5% by mass or more. Furthermore, the upper limit of (SiO2-Al2O3) may be 57% by mass or less, 56% by mass or less, 55% by mass or less, 54% by mass or less, 53.5% by mass or less, 53% by mass or less, or even 52% by mass or less.

[0019] (SiO2-B2O3-Al2O3) From the viewpoint of improving the acid resistance of glass, the lower limit of the value obtained by subtracting the B2O3 content from the SiO2 content and then further subtracting the Al2O3 content (SiO2-B2O3-Al2O3) may be 45 mass% or more, 46 mass% or more, 47 mass% or more, more than 48 mass%, 48.5 mass% or more, more than 49 mass%, or even 49.5 mass% or more. Furthermore, the upper limit of (SiO2-B2O3-Al2O3) may be 56 mass% or less, 55 mass% or less, 54 mass% or less, 53 mass% or less, 53.5 mass% or less, 52 mass% or less, or even 51 mass% or less.

[0020] (MgO, CaO) MgO and CaO are components that adjust the devitrification temperature and viscosity during glass formation. Furthermore, MgO and CaO are also components that improve Young's modulus. The MgO content is 1% by mass or more and 10% by mass or less, with the lower limit being 1.5% by mass or more, 1.8% by mass or more, or even 2% by mass or more. The upper limit of the MgO content may be 8% by mass or less, 6% by mass or less, 5% by mass or less, 4.5% by mass or less, or even 4% by mass or less.

[0021] When the CaO content is 10% by mass or more and 30% by mass or less, the devitrification temperature and the viscosity during melting of the glass can be kept within a range suitable for producing a glass composition while preventing an excessive increase in the devitrification temperature. The lower limit of the CaO content can be 15% by mass or more, 16% by mass or more, 17% by mass or more, 18% by mass or more, or even 19% by mass or more, and in some cases 20% by mass or more. The upper limit of the CaO content can be 28% by mass or less, 27% by mass or less, 26% by mass or less, 25% by mass or less, or even 24% by mass or less.

[0022] (MgO + CaO) With respect to the meltability and formability of glass, the value of the sum of the contents of MgO and CaO (MgO + CaO) is important. From the viewpoint of obtaining meltability and formability suitable for glass production, the lower limit of (MgO + CaO) may be 8 mass% or more, 9 mass% or more, 9.5 mass% or more, 10 mass% or more, 10.5 mass% or more, 11 mass% or more, 11.5 mass% or more, 12 mass% or more, 13 mass% or more, 13.5 mass% or more, 14 mass% or more, 14.5 mass% or more, 15 mass% or more, 16 mass% or more, 17 mass% or more, 18 mass% or more, 19 mass% or more, 20 mass% or more, 21 mass% or more, or 22 mass% or more. Furthermore, the upper limit of (MgO + CaO) is preferably 40% by mass or less, and can be 35% by mass or less, 32% by mass or less, 30% by mass or less, 29% by mass or less, 28% by mass or less, 27% by mass or less, 26.5% by mass or less, 26% by mass or less, 25% by mass or less, 24% by mass or less, or 23% by mass or less.

[0023] (SrO) Composition A-1 may further contain strontium oxide (SrO). SrO is a component that adjusts the devitrification temperature and viscosity during glass formation. On the other hand, excessive SrO content reduces the acid resistance of the glass. The lower limit of the SrO content may be 0.1 mass% or more, 0.5 mass% or more, 1 mass% or more, 2 mass% or more, 3 mass% or more, 4 mass% or more, 5 mass% or more, 6 mass% or more, 7 mass% or more, or even 8 mass% or more. The upper limit of the SrO content may be 15 mass% or less, 12 mass% or less, 10 mass% or less, 8 mass% or less, 6 mass% or less, 5 mass% or less, 4 mass% or less, 3 mass% or less, 2 mass% or less, 1.5 mass% or less, 1 mass% or less, or 0.5 mass% or less. The upper limit of the SrO content may be 0.1 mass% or less. Composition A-1 may be substantially free of SrO.

[0024] (MgO + CaO + SrO) The total content of MgO, CaO, and SrO (MgO + CaO + SrO) is important for the meltability and formability of glass. From the viewpoint of obtaining meltability and formability suitable for glass production, the lower limit of (MgO + CaO + SrO) is preferably 15 mass% or more, and may be 18 mass% or more, 20 mass% or more, 21 mass% or more, 22 mass% or more, 23 mass% or more, 24 mass% or more, 25 mass% or more, 26 mass% or more, 27 mass% or more, or 28 mass% or more. Furthermore, the upper limit of (MgO + CaO + SrO) is preferably 40 mass% or less, and may be 38 mass% or less, 36 mass% or less, 35 mass% or less, or 34 mass% or less.

[0025] (BaO) Composition A-1 may further contain barium oxide (BaO). BaO is a component that adjusts the devitrification temperature and viscosity during glass formation. On the other hand, excessive BaO content reduces the acid resistance of the glass. The upper limit of the BaO content may be 10% by mass or less, or may be 5% 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, or even 0.1% by mass or less. Composition A-1 may be substantially free of BaO.

[0026] (MgO + CaO + SrO + BaO) The value of the total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) is important for the meltability and formability of glass. From the viewpoint of obtaining meltability and formability suitable for glass production, the lower limit of (MgO + CaO + SrO + BaO) is preferably 15 mass% or more, and may be 18 mass% or more, 20 mass% or more, 21 mass% or more, 22 mass% or more, 23 mass% or more, 24 mass% or more, 25 mass% or more, 26 mass% or more, 27 mass% or more, or 28 mass% or more. Furthermore, the upper limit of (MgO + CaO + SrO + BaO) is preferably 40 mass% or less, and may be 38 mass% or less, 36 mass% or less, 35 mass% or less, or 34 mass% or less.

[0027] (ZnO) Composition A-1 may further contain zinc oxide (ZnO). When contained in composition A-1, ZnO is a component that adjusts the devitrification temperature and viscosity during glass formation. However, since the raw material for ZnO is relatively expensive, its content is preferably low. The upper limit of the ZnO content in composition A-1 may be 10% by mass or less, 5% 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, or even 0.1% by mass or less. Composition A-1 may be substantially free of ZnO.

[0028] (Li2O, Na2O, K2O) Alkali metal oxides (Li2O, Na2O, K2O) are components that adjust the devitrification temperature and viscosity during glass formation. When the total content of alkali metal oxides (Li2O + Na2O + K2O) is 0% by mass or more and 4% by mass or less, the devitrification temperature and viscosity of the glass melt can be kept within ranges suitable for glass production while suppressing an excessive increase in the devitrification temperature. Furthermore, while suppressing an increase in the melting point of the glass and enabling more uniform melting of the glass raw materials, the glass transition temperature does not decrease excessively, ensuring high heat resistance of the glass. Furthermore, the acid resistance of the glass is improved. The lower limit of (Li2O + Na2O + K2O) may be greater than 0% by mass or may be 0.1% by mass or more. The upper limit of (Li2O + Na2O + K2O) may be 3% by mass or less, or 2% by mass or less, or less than 2% by mass. The value of (Li2O + Na2O + KO) may be 0.1 mass% or less. Composition A-1 may be substantially free of alkali metal oxides. Li2O, Na2O, and KO are each optional components. In other words, the lower limit of the content of each of these components may be 0.

[0029] The lower limit of the lithium oxide (LiO) content may be 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, or even 0.4% by mass or more. The upper limit of the LiO content may be 4% by mass or less, 3% by mass or less, 2% by mass or less, 1.5% by mass or less, or even 1% by mass or less.

[0030] The lower limit of the sodium oxide (NaO) content may be 0.1% by mass or more, or 0.2% by mass or more, and the upper limit of the NaO content may be 4% by mass or less, or 3% by mass or less, 2% by mass or less, 1.5% by mass or less, or even 1% by mass or less.

[0031] The lower limit of the potassium oxide (K2O) content may be 0.1 mass% or more, or 0.2 mass% or more, and the upper limit of the K2O content may be 4 mass% or less, or 3 mass% or less, 2 mass% or less, 1.5 mass% or less, or even 1 mass% or less.

[0032] (TiO2) Composition A-1 may further contain titanium dioxide (TiO2). TiO2 is a component that improves the meltability and chemical durability of glass and improves its ultraviolet absorption characteristics. TiO2 is also a component that improves the acid resistance and water resistance of glass. However, since the raw material for TiO2 is relatively expensive, a low TiO2 content is preferable. The lower limit of the TiO2 content may be 0.1% by mass or more. The upper limit of the TiO2 content may be 10% by mass or less, or may be 5% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.3% by mass or less, or even 0.2% by mass or less. Composition A-1 may be substantially free of TiO2.

[0033] (ZrO2) Composition A-1 may further contain zirconium oxide (ZrO2). ZrO2 is a component that adjusts the devitrification temperature and viscosity during glass formation. ZrO2 is also a component that improves the acid resistance and alkali resistance of the glass. ZrO2 is also a component that improves the Young's modulus and heat resistance of the glass. However, since the raw material for ZrO2 is relatively expensive, its content is preferably low. The upper limit of the ZrO2 content may be 7% by mass or less, or may be 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, or even 0.1% by mass or less. Composition A-1 may be substantially free of ZrO2.

[0034] (Fe) Composition A-1 may further contain iron trioxide (Fe2O3). Iron (Fe) is usually Fe 2+or Fe 3+ It exists in the state of Fe 3+ is a component that enhances the ultraviolet absorption properties of glass, and Fe 2+ is a component that enhances the heat absorption properties of glass. Even if not intentionally included, Fe may be inevitably mixed in as a result of industrial raw materials. A low Fe content can prevent glass coloration. The upper limit of the Fe content, expressed in T-Fe2O3, can be 5% by mass or less, or 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, or even 0.1% by mass or less, less than 0.1% by mass, 0.08% by mass or less, 0.05% by mass or less, 0.04% by mass or less, or even 0.03% by mass or less. The lower limit of the Fe content, expressed in T-Fe2O3, can be 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, or even 0.2% by mass or more. Particularly in glass compositions with low alkali metal oxide contents, trace amounts of iron oxide can contribute to promoting fining of the glass.

[0035] (F2, Cl2) Composition A-1 may further contain fluorine (F2) and chlorine (Cl2). F2 is easily volatile, which may cause scattering during melting, and also makes it difficult to control its content in the glass. The upper limit of the F2 content may be 5% by mass or less, or may be 2% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.2% by mass or less, or even 0.1% by mass or less. Composition A-1 may be substantially free of F2.

[0036] Cl2 is easily volatile, which may cause scattering during melting, and also makes it difficult to control its content in the glass. The upper limit of the Cl2 content may be 5% by mass or less, or may be 2% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.2% by mass or less, or even 0.1% by mass or less. Composition A-1 may be substantially free of Cl2.

[0037] Composition A-1 may have the preferred composition described in mass % in the following paragraphs.

[0038] A composition containing the components 50≦SiO2≦67, 0≦B2O3<2, 5≦Al2O3≦15, 45≦(SiO2-Al2O3)≦57, 1≦MgO≦10, 15≦CaO≦30, 0≦T-Fe2O3≦5, and substantially containing no alkali metal oxides.

[0039] A composition containing the following components: 57≦SiO2≦67, 0≦B2O3<2, 5≦Al2O3≦15, 45≦(SiO2−Al2O3)≦57, 1≦MgO≦10, 15≦CaO≦30, 0≦(Li2O+Na2O+K2O)≦4, 0≦T-Fe2O3≦5.

[0040] A composition containing the following components: 55≦SiO2≦67, 0.1≦B2O3<2, 5≦Al2O3≦15, 45≦(SiO2−Al2O3)≦57, 1≦MgO≦10, 15≦CaO≦30, 0≦(Li2O+Na2O+K2O)≦4, 0≦T-Fe2O3≦5.

[0041] A composition containing the following components: 50≦SiO2≦67, 0≦B2O3<2, 5≦Al2O3≦15, 45≦(SiO2-Al2O3)≦57, 1≦MgO≦10, 10≦CaO≦30, 1≦SrO≦15, 0≦(Li2O+Na2O+K2O)≦4, 0≦T-Fe2O3≦5.

[0042] In each of the above compositions, the relationship 0≦ZnO≦2 is further satisfied.

[0043] A composition that does not substantially contain B2O3 in each of the above compositions (excluding compositions in which 0.1≦B2O3<2 is satisfied).

[0044] (Composition A-2) Composition A-2 contains the following components in mass %: 65<SiO2≦75, 0≦B2O3<2, 5≦Al2O3≦15, 50<(SiO2-Al2O3)≦60, 1≦MgO≦10, 10≦CaO≦25, 0≦(Li2O+Na2O+K2O)≦4, 0≦T-Fe2O3≦5

[0045] The glass fiber having the glass composition A-2 has excellent heat resistance, is suppressed from being deformed when heated to a high temperature, and has excellent chemical durability, particularly acid resistance.

[0046] Each component in glass composition A-2 will be described below, with the exception that descriptions of the role of each component that overlap with glass composition A-1 will be omitted.

[0047] (SiO2) SiO2 is also the main component in composition A-2. The SiO2 content is greater than 65 mass% and not more than 75 mass%, with the lower limit being 66 mass% or more. The upper limit of the SiO2 content can be 72 mass% or less, 70 mass% or less, 69 mass% or less, 68 mass% or less, or even 67 mass% or less.

[0048] (B2O3)(Al2O3) In composition A-2, the contents of B2O3 and Al2O3 may have the same upper and lower limits as in composition A-1.

[0049] (SiO2-Al2O3) In composition A-2, from the viewpoint of improving the acid resistance of the glass, the lower limit of the value obtained by subtracting the Al2O3 content from the SiO2 content (SiO2-Al2O3) can be more than 50 mass%, or 51 mass% or more, 52 mass% or more, or even more than 53 mass%. Furthermore, the upper limit of (SiO2-Al2O3) can be 60 mass% or less, or 59 mass% or less, 58 mass% or less, or even 57 mass% or less.

[0050] (MgO, CaO) In composition A-2, the content of MgO may have the same upper and lower limits as in composition A-1.

[0051] In composition A-2, the CaO content is 10% by mass or more and 25% by mass or less. The lower limit of the CaO content can be 12% by mass or more, 13% by mass or more, 14% by mass or more, or even more than 15% by mass. The upper limit of the CaO content can be 23% by mass or less, 22% by mass or less, 21% by mass or less, or even 20% by mass or less.

[0052] (SrO) Composition A-2 may further contain SrO. In composition A-2, the upper limit of the SrO content may be 10% by mass or less, 5% 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, or even less than 0.1% by mass. Composition A-2 may be substantially free of SrO.

[0053] (BaO) Composition A-2 may further contain BaO. The BaO content in composition A-2 may have the same upper and lower limits as in composition A-1. Composition A-2 may be substantially free of BaO.

[0054] (ZnO) Composition A-2 may further contain ZnO. The ZnO content in composition A-2 may have the same upper and lower limits as in composition A-1. Composition A-2 may be substantially free of ZnO.

[0055] (Li2O, Na2O, KO) In composition A-2, the total content of alkali metal oxides (Li2O + Na2O + KO) is 0% by mass or more and 4% by mass or less. The lower limit of (Li2O + Na2O + KO) can be 0.1% by mass or more, 1% by mass or more, 1.5% by mass or more, or even 2% by mass or more. The upper limit of (Li2O + Na2O + KO) can be 3.5% by mass or less, or 3% by mass or less. Composition A-2 may be substantially free of alkali metal oxides. Li2O, Na2O, and KO are each optional components. In other words, the lower limit of the content of each of these components may be 0.

[0056] In composition A-2, LiO makes a particularly large contribution to the effects based on the alkali metal oxide described above. From this perspective, the lower limit of the LiO content in composition A-2 can be 0.1% by mass or more, 0.5% by mass or more, or even 1% by mass or more. The upper limit of the LiO content can be 4% by mass or less, 3% by mass or less, 2.5% by mass or less, or 2% by mass or less.

[0057] In composition A-2, the contents of Na2O and K2O may have the same upper and lower limits as those in composition A-1.

[0058] (TiO2) Composition A-2 may further contain TiO2. The content of TiO2 in composition A-2 may have the same upper and lower limits as composition A-1. Composition A-2 may be substantially free of TiO2.

[0059] (ZrO2) Composition A-2 may further contain ZrO2. The content of ZrO2 in composition A-2 may have the same upper and lower limits as in composition A-1. Composition A-2 may be substantially free of ZrO2.

[0060] (Fe)(F2, Cl2) Composition A-2 may further contain the above components. The preferred contents of these components and other details are the same as those of composition A-1, so further description is omitted.

[0061] (Composition A-3) Composition A-3 contains the following components in mass %: 60≦SiO2≦75, 0≦B2O3≦4, 5≦Al2O3≦15, 47≦(SiO2−Al2O3)≦60, 1≦MgO≦10, 10≦CaO≦25, 4<(Li2O+Na2O+K2O)<9, 0≦T-Fe2O3≦5

[0062] The glass fiber having the glass composition A-3 has excellent heat resistance, is suppressed from being deformed when heated to a high temperature, and has excellent chemical durability, particularly acid resistance.

[0063] Each component in glass composition A-3 is described below. However, descriptions of the role of each component that overlap with those in glass compositions A-1 or A-2 will be omitted. (SiO2) SiO2 is also the main component in composition A-3. The SiO2 content is 60% by mass or more and 75% by mass or less, but the lower limit can be 62% by mass or more, 63% by mass or more, 64% by mass or more, or even more than 65% by mass. The upper limit of the SiO2 content can be 72% by mass or less, 70% by mass or less, 69% by mass or less, 68% by mass or less, or even 67% by mass or less.

[0064] (B2O3) B2O3 is a component that forms the skeleton of glass. B2O3 is also a component that adjusts the devitrification temperature and viscosity during glass formation. The lower limit of the B2O3 content may be 0.1 mass% or more. The upper limit of the B2O3 content may be 4 mass% or less, 3 mass% or less, less than 2 mass%, 1.5 mass% or less, 1 mass% or less, or 0.5 mass% or less. The upper limit of the B2O3 content may be 0.1 mass% or less. Composition A-1 may be substantially free of B2O3.

[0065] (Al2O3) In composition A-3, the content of Al2O3 may have the same upper and lower limits as in composition A-1.

[0066] (SiO2-Al2O3) In composition A-3, from the viewpoint of improving the acid resistance of the glass, the lower limit of the value obtained by subtracting the Al2O3 content from the SiO2 content (SiO2-Al2O3) may be 47 mass% or more, more than 49 mass%, more than 50 mass%, 51 mass% or more, 52 mass% or more, or even more than 53 mass%. Furthermore, the upper limit of (SiO2-Al2O3) may be 60 mass% or less, 59 mass% or less, 58 mass% or less, or even 57 mass% or less.

[0067] (MgO, CaO) In composition A-3, the content of MgO may have the same upper and lower limits as in composition A-1.

[0068] In composition A-3, the CaO content is 10% by mass or more and 25% by mass or less. The lower limit of the CaO content can be 12% by mass or more, 13% by mass or more, 14% by mass or more, or even more than 15% by mass. The upper limit of the CaO content can be 23% by mass or less, 21% by mass or less, 20% by mass or less, 19% by mass or less, or even 18% by mass or less.

[0069] (MgO + CaO) In composition A-3, when the ease of forming the glass composition is important, the sum of the contents of MgO and CaO (MgO + CaO) can be 11% by mass or more and 35% by mass or less. In composition A-3, by ensuring that the total content of alkali metal oxides and the total content of MgO and CaO are within an appropriate range, the devitrification temperature and viscosity of the glass during melting can be set within ranges suitable for producing a glass composition while suppressing an excessive increase in the devitrification temperature. Furthermore, high acid resistance of the glass can be ensured. The lower limit of (MgO + CaO) can be 13% by mass or more, more than 14% by mass, 15% by mass or more, 16% by mass or more, or even more than 17% by mass. The upper limit of (MgO + CaO) can be 30% by mass or less, 28% by mass or less, 26% by mass or less, 25% by mass or less, or even 24% by mass or less.

[0070] (SrO) Composition A-3 may further contain SrO. The SrO content in composition A-3 may have the same upper and lower limits as in composition A-2. Composition A-3 may be substantially free of SrO.

[0071] (BaO) Composition A-3 may further contain BaO. The BaO content in composition A-3 may have the same upper and lower limits as in composition A-1. Composition A-3 may be substantially free of BaO.

[0072] (ZnO) Composition A-3 may further contain ZnO. The ZnO content in composition A-3 may have the same upper and lower limits as in composition A-1. Composition A-3 may be substantially free of ZnO.

[0073] (Li2O, Na2O, KO) In composition A-3, the total content of alkali metal oxides (Li2O + Na2O + KO) is greater than 4% by mass and less than 9% by mass. The lower limit of (Li2O + Na2O + KO) can be 4.5% by mass or more, or 5% by mass or more. The upper limit of (Li2O + Na2O + KO) can be 8.5% by mass or less, or 8% by mass or less, 7.5% by mass or less, or even 7% by mass or less. Li2O, Na2O, and KO are each optional components. In other words, the lower limit of the content of each of these components may be 0.

[0074] In composition A-3, LiO makes a particularly large contribution to the effects based on the alkali metal oxide described above. From this viewpoint, the lower limit of the LiO content in composition A-3 can be 0.1% by mass or more, 0.5% by mass or more, or even 1% by mass or more. The upper limit of the LiO content can be 3% by mass or less, or 2% by mass or less.

[0075] In composition A-3, the lower limit of the NaO content may be 0.1% by mass or more, 0.2% by mass or more, 0.5% by mass or more, 1% by mass or more, 1.5% by mass or more, or even 2% by mass or more. The upper limit of the NaO content may be 8% by mass or less, 7% by mass or less, or even 6% by mass or less.

[0076] In composition A-3, the lower limit of the KO content may be 0.1 mass% or more, 0.2 mass% or more, or 0.3 mass% or more, and the upper limit of the KO content may be 3 mass% or less, 2 mass% or less, or even 1 mass% or less.

[0077] (TiO2) Composition A-3 may further contain TiO2. In composition A-3, the content of TiO2 may have the same upper and lower limits as in composition A-1. Composition A-3 may be substantially free of TiO2.

[0078] (ZrO2) Composition A-3 may further contain ZrO2. In composition A-3, the content of ZrO2 may have the same upper and lower limits as in composition A-1. Composition A-3 may be substantially free of ZrO2.

[0079] (Fe)(F2, Cl2) Composition A-3 may further contain the above components. The preferred contents of these components and other details are the same as those of composition A-1, so further description is omitted.

[0080] (Composition A-4) Composition A-4 contains the following components in mass %: 60≦SiO2≦75, 0≦B2O3≦4, 5≦Al2O3≦15, 47≦(SiO2-Al2O3)≦60, 5≦CaO≦20, 6≦Na2O≦20, 9≦(Li2O+Na2O+K2O)≦20, 0≦T-Fe2O3≦5

[0081] The glass composition having the glass composition A-4 is also excellent in heat resistance and chemical durability.

[0082] Each component in glass composition A-4 is described below. However, descriptions of the role of each component that overlap with those in glass compositions A-1 to A-3 will be omitted. (SiO2) SiO2 is also the main component in composition A-4. In composition A-4, the SiO2 content may have the same upper and lower limits as in composition A-3.

[0083] (B2O3) In composition A-4, the content of B2O3 may have the same upper and lower limits as in composition A-3.

[0084] (Al2O3) In composition A-4, the content of Al2O3 may have the same upper and lower limits as in composition A-1.

[0085] (SiO2-Al2O3) In composition A-4, from the viewpoint of improving the acid resistance of the glass, the value obtained by subtracting the Al2O3 content from the SiO2 content (SiO2-Al2O3) may have upper and lower limits similar to those of composition A-3.

[0086] (MgO, CaO) Composition A-4 may further contain MgO. However, the inclusion of MgO in composition A-4 is not essential. The lower limit of the MgO content may be 0% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 1.5% by mass or more, or even 2% by mass or more. The upper limit of the MgO content may be 10% by mass or less, 8% by mass or less, 6% by mass or less, 5% by mass or less, or even 4% by mass or less.

[0087] In composition A-4, the CaO content is 5% by mass or more and 20% by mass or less. The lower limit of the CaO content can be 6% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, or even 10% by mass or more. The upper limit of the CaO content can be 18% by mass or less, 17% by mass or less, 16% by mass or less, or even 15% by mass or less.

[0088] (MgO + CaO) In composition A-4, when the ease of forming the glass composition is important, the sum of the contents of MgO and CaO (MgO + CaO) can be 5% by mass or more and 30% by mass or less. In composition A-4, by ensuring that the total content of alkali metal oxides and the sum of the contents of MgO and CaO are within an appropriate range, the devitrification temperature and viscosity during melting of the glass can be set within ranges suitable for producing the glass composition while suppressing an excessive increase in the devitrification temperature. In addition, high acid resistance of the glass can be ensured. The lower limit of (MgO + CaO) can be 6% by mass or more, or can be 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 even 13% by mass or more. The upper limit of (MgO + CaO) can be 26% by mass or less, 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, or even 18% by mass or less.

[0089] (SrO) Composition A-4 may further contain SrO. The SrO content in composition A-4 may have the same upper and lower limits as in composition A-2. Composition A-4 may be substantially free of SrO.

[0090] (BaO) Composition A-4 may further contain BaO. The BaO content in composition A-4 may have the same upper and lower limits as those in composition A-1. Composition A-4 may be substantially free of BaO.

[0091] (ZnO) Composition A-4 may further contain ZnO. The ZnO content in composition A-4 may have the same upper and lower limits as in composition A-1. Composition A-4 may be substantially free of ZnO.

[0092] (Li2O, Na2O, KO) In composition A-4, the total content of alkali metal oxides (Li2O + Na2O + KO) is 9% by mass or more and 20% by mass or less. The lower limit of (Li2O + Na2O + KO) can be 9.5% by mass or more, or 10% by mass or more. The upper limit of (Li2O + Na2O + KO) can be 18% by mass or less, or 16% by mass or less, less than 15% by mass, 14% by mass or less, 13% by mass or less, 12.5% ​​by mass or less, or 12% by mass or less. Li2O and KO are each optional components. In other words, the lower limit of the content of each of these components may be 0 as long as the total content of alkali metal oxides is 9% by mass or more.

[0093] In composition A-4, LiO contributes particularly highly to the effects based on the alkali metal oxides described above. Furthermore, the inclusion of LiO can lower the working temperature of the glass melt when forming the glass composition. Lowering the working temperature facilitates the formation of the glass composition, improving productivity. On the other hand, excessive LiO content lowers the glass transition temperature and reduces the heat resistance of the glass. The lower limit of the LiO content in composition A-4 can be 0% by mass or more, 0.1% by mass or more, 0.5% by mass or more, or even 1% by mass or more. The upper limit of the LiO content can be 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, or even less than 2% by mass.

[0094] The Na2O content is 6% by mass or more and 20% by mass or less. When the Na2O content is within this range, the effects based on the alkali metal oxide described above are more reliably achieved. The lower limit of the Na2O content may be 7% by mass or more, or even 8% by mass or more. The upper limit of the Na2O content may be 17% by mass or less, 16% by mass or less, less than 15% by mass, 14% by mass or less, 13% by mass or less, or even 12% by mass or less.

[0095] In composition A-4, the lower limit of the KO content may be 0% by mass or more, 0.1% by mass or more, or even 0.5% by mass or more. The upper limit of the KO content may be 5% by mass or less, 3% by mass or less, 2% by mass or less, less than 2% by mass, or even 1% by mass or less.

[0096] (TiO2) Composition A-4 may further contain TiO2. In composition A-4, the content of TiO2 may have the same upper and lower limits as in composition A-1. Composition A-4 may be substantially free of TiO2.

[0097] (ZrO2) Composition A-4 may further contain ZrO2. In composition A-4, the content of ZrO2 may have the same upper and lower limits as in composition A-1. Composition A-4 may be substantially free of ZrO2.

[0098] (Fe)(F2, Cl2) Composition A-4 may further contain the above components. The preferred contents of these components and other details are the same as those of composition A-1, so further description is omitted.

[0099] (Glass Composition B) Another example of the glass composition (hereinafter referred to as glass composition B) contains, expressed in mass%, the following components: 50≦SiO2≦75, 0≦B2O3≦4, 0.1≦(MgO+CaO)≦20, 9≦(Li2O+Na2O+K2O)≦20, and 5≦ZrO2≦20.

[0100] Glass composition B may not substantially contain any components other than the above-mentioned components. Furthermore, glass composition B can provide glass fibers with high chemical durability.

[0101] Each component in glass composition B is described below. (SiO2) SiO2 is a component that forms the glass skeleton and is the main component of composition B. SiO2 also adjusts the devitrification temperature and viscosity during glass formation. It also improves water resistance and acid resistance. The SiO2 content is 50% by mass or more and 75% by mass or less. The lower limit of the SiO2 content can be 52% by mass or more, 54% by mass or more, 56% by mass or more, 58% by mass or more, 60% by mass or more, 62% by mass or more, 63% by mass or more, 64% by mass or more, more than 65% by mass, or even more than 66% by mass. The upper limit of the SiO2 content can be 74% by mass or less, 73% by mass or less, 71% by mass or less, or even 70% by mass or less.

[0102] (BO) Composition B may further contain BO. BO is a component that forms the glass skeleton. BO also adjusts the devitrification temperature and viscosity during glass formation. However, excessive BO reduces the acid resistance of the glass. The upper limit of the BO content may be 4% by mass or less, 3% by mass or less, less than 2% by mass, 1.5% by mass or less, 1% by mass or less, 0.5% by mass or less, or even 0.1% by mass or less. Composition B may be substantially free of BO.

[0103] (Al2O3) Composition B may further contain Al2O3. Al2O3 is a component that forms the skeleton of the glass. Al2O3 also adjusts the devitrification temperature and viscosity during glass formation and improves the water resistance of the glass. On the other hand, excessive Al2O3 content reduces the acid resistance of the glass. The upper limit of the Al2O3 content may be 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, or even 1.5% by mass or less.

[0104] (BO+AlO) In composition B, when glass formability and acid resistance are important, the sum of the BO and AlO contents (BO+AlO) can be important. In composition B, (BO+AlO) can be 5% by mass or less. This suppresses an increase in the devitrification temperature of the glass that would make glass manufacturing difficult, while also enhancing the acid resistance of the glass. Furthermore, the melting point of the glass is not excessively elevated, improving uniformity during melting of the raw materials. The upper limit of (BO+AlO) can be 4% by mass or less, 3% by mass or less, 2% by mass or less, or even less than 1.5% by mass.

[0105] (MgO, CaO) Composition B may further contain MgO. MgO is a component that adjusts the devitrification temperature and viscosity during glass formation. MgO also adjusts the acid resistance and water resistance of the glass composition. The lower limit of the MgO content may be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 1.5% by mass or more, or even more than 2% by mass. The upper limit of the MgO content may be 15% by mass or less, 12% by mass or less, 10% by mass or less, 8% by mass or less, 6% by mass or less, or even 5% by mass or less.

[0106] Composition B may further contain CaO. CaO is a component that adjusts the devitrification temperature and viscosity during glass formation. CaO also adjusts the acid resistance and water resistance of the glass composition. The lower limit of the CaO content may be 0.1% by mass or more, 1% by mass or more, 2% by mass or more, or even more than 3% by mass. The upper limit of the CaO content may be 15% by mass or less, 12% by mass or less, 10% by mass or less, or even 8% by mass or less.

[0107] In composition B, when the sum of the contents of MgO and CaO (MgO + CaO) is 0.1 mass% or more and 20 mass% or less, the devitrification temperature and viscosity of the glass melt can be kept within a range suitable for glass production while suppressing an excessive increase in the devitrification temperature. This range also makes it possible to improve the chemical durability of the glass. The lower limit of (MgO + CaO) can be 2 mass% or more, 4 mass% or more, 6 mass% or more, 8 mass% or more, or even 9 mass% or more. The upper limit of (MgO + CaO) can be 20 mass% or less, 18 mass% or less, 16 mass% or less, 14 mass% or less, or even 13 mass% or less. In composition B, MgO and CaO are each optional components. In other words, the lower limit of the content of these components may be 0 as long as the total content is 0.1 mass% or more.

[0108] (SrO) Composition B may further contain SrO. SrO is a component that adjusts the devitrification temperature and viscosity during glass formation. On the other hand, excessive SrO content reduces the acid resistance of the glass. The upper limit of the SrO content may be 10% by mass or less, 5% 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, or even 0.1% by mass or less. Composition B may be substantially free of SrO.

[0109] (BaO) Composition B may further contain BaO. BaO is a component that adjusts the devitrification temperature and viscosity during glass formation. On the other hand, excessive BaO content reduces the acid resistance of the glass. The upper limit of the BaO content may be 10% by mass or less, 5% 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, or even 0.1% by mass or less. Composition B may be substantially free of BaO.

[0110] (ZnO) Composition B may further contain ZnO. ZnO is a component that adjusts the devitrification temperature and viscosity during glass formation. On the other hand, ZnO is easily volatilized and may scatter during melting. Therefore, excessive ZnO content exacerbates fluctuations in the glass component ratio due to volatilization, making it difficult to control the glass composition. Furthermore, since the raw material for ZnO is relatively expensive, its content should be low. The upper limit of the ZnO content may be 10% by mass or less, 5% by mass or less, less than 3% by mass, 2% by mass or less, 1.5% by mass or less, 1% by mass or less, 0.5% by mass or less, or even 0.1% by mass or less. Composition B may be substantially free of ZnO.

[0111] (Li2O, Na2O, K2O) In composition B, alkali metal oxides (Li2O, Na2O, K2O) are components that adjust the devitrification temperature and viscosity during glass formation. In addition, alkali metal oxides (Li2O, Na2O, K2O) are also components that adjust the acid resistance and water resistance of the glass. Li2O and K2O are each optional components. In other words, the lower limit of the content of each of these components may be 0.

[0112] The lower limit of the LiO content may be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, or 1.5% by mass or more. The upper limit of the LiO content may be 5% by mass or less, 4% by mass or less, 3.5% by mass or less, or even 3% by mass or less.

[0113] The lower limit of the Na2O content may be 0.1% by mass or more, 1% by mass or more, or 3% by mass or more. The Na2O content may be 6% by mass or more and 20% by mass or less. In this case, the devitrification temperature and viscosity of the glass melt can be kept within a range suitable for glass production while suppressing an excessive increase in the devitrification temperature. Furthermore, an increase in the melting point of the glass can be suppressed, enabling more uniform melting of the glass raw materials, while ensuring high heat resistance of the glass without an excessive decrease in the glass transition temperature. Furthermore, within this range, the chemical durability of the glass can be improved. The lower limit of Na2O may be 7% by mass or more, 7.5% by mass or more, or even 8% by mass or more. The upper limit of Na2O may be 18% by mass or less, 16% by mass or less, 15% by mass or less, 14% by mass or less, 13% by mass or less, or even 12% by mass or less.

[0114] The lower limit of the KO content may be 0.1% by mass or more, and may be greater than 0.5% by mass. The upper limit of the KO content in composition B may be 10% by mass or less, 5% by mass or less, less than 4% by mass, 3% by mass or less, or even less than 2% by mass.

[0115] In composition B, when the total alkali metal oxide content (Li2O + Na2O + KO) is 9% by mass or more and 20% by mass or less, the devitrification temperature and viscosity of the glass melt can be kept within a range suitable for glass production while suppressing an excessive increase in the devitrification temperature. Furthermore, the increase in the melting point of the glass can be suppressed, enabling more uniform melting of the glass raw materials, while ensuring high heat resistance of the glass without an excessive decrease in the glass transition temperature. Furthermore, this range also enables improved chemical durability of the glass. The lower limit of (Li2O + Na2O + KO) can be 9.5% by mass or more, or 10% by mass or more. The upper limit of (Li2O + Na2O + KO) can be 18% by mass or less, or 16% by mass or less, 15% by mass or less, 14% by mass or less, less than 13% by mass, or even less than 12% by mass. Li2O, Na2O, and KO are each optional components. In other words, the lower limit of the content of each of these components may be 0 as long as the total content of alkali metal oxides is 9 mass % or more.

[0116] (TiO2) Glass composition B may further contain TiO2. TiO2 is a component that improves the meltability and chemical durability of glass. However, since the raw material for TiO2 is relatively expensive, its content is preferably low. The upper limit of the TiO2 content may be 5% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, or even 0.1% by mass or less. Composition B may be substantially free of TiO2.

[0117] (ZrO2) ZrO2 is a component that adjusts the devitrification temperature and viscosity during glass formation. ZrO2 also adjusts the acid resistance and water resistance of the glass composition. Furthermore, ZrO2 is a component that improves Young's modulus. When the ZrO2 content in composition B is 5% by mass or more and 20% by mass or less, the increase in the devitrification temperature of the glass, which would make glass production difficult, is suppressed, and the water resistance and acid resistance of the glass are improved. However, since the raw material for ZrO2 is relatively expensive, a lower ZrO2 content is preferable. The lower limit of the ZrO2 content may be greater than 5% by mass, 5.5% by mass or more, 6% by mass or more, 6.5% by mass or more, or even 7% by mass or more. The upper limit of the ZrO2 content may be 18% by mass or less, 15% by mass or less, 12% by mass or less, 10% by mass or less, 9.5% by mass or less, 9% by mass or less, 8.5% by mass or less, or even 8% by mass or less.

[0118] (Fe) Iron (Fe) contained in the glass composition is usually Fe 2+ or Fe 3+ It exists in the state of Fe 3+ is a component that enhances the ultraviolet absorption characteristics of the glass composition, and Fe 2+ is a component that enhances the heat absorption properties of the glass composition. Even if not intentionally included, Fe may be inevitably mixed in as an industrial raw material. A low Fe content can prevent coloration of the glass composition. The upper limit of the Fe content, expressed in T-Fe2O3, can be 5 mass% or less, or 2 mass% or less, 1 mass% or less, 0.5 mass% or less, 0.4 mass% or less, 0.3 mass% or less, 0.2 mass% or less, or even 0.1 mass% or less, less than 0.1 mass%, 0.08 mass% or less, 0.05 mass% or less, 0.04 mass% or less, or even 0.03 mass% or less. The lower limit of the Fe content, expressed in T-Fe2O3, can be 0.01 mass% or more, 0.05 mass% or more, 0.1 mass% or more, or even 0.2 mass% or more. Particularly in glass compositions with low alkali metal oxide contents, trace amounts of iron oxide can contribute to promoting fining of the glass.

[0119] (F2, Cl2) Composition B may further contain fluorine (F2) and chlorine (Cl2). F2 is easily volatile, which may cause scattering during melting, and there is also the problem that the content in the glass is difficult to control. The upper limit of the F2 content may be 5% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.2% by mass or less, or even 0.1% by mass or less. F2 may not be substantially present.

[0120] Since Cl2 is easily volatile, it may scatter during melting, and there is also the problem that its content in the glass is difficult to control. The upper limit of the Cl2 content may be 5% by mass or less, or may be 2% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.2% by mass or less, or even 0.1% by mass or less. Cl2 may not be substantially contained.

[0121] Glass composition A and glass composition B may further contain the following components as long as the effects of the present invention are obtained.

[0122] (Other Components) Glass Composition A and Glass Composition B may contain at least one other component selected from P2O5, Sc2O3, YO3, La2O3, CeO2, Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, WO3, Nb2O5, YO3, MoO3, Ta2O5, MnO2, and Cr2O3 in a content of 0% to 5% by mass, respectively. The allowable content of each of these components may be less than 2% by mass, less than 1% by mass, less than 0.5% by mass, or even less than 0.1% by mass. The total allowable content of these components may be 5% by mass or less, or may be less than 2%, less than 1%, less than 0.5%, or even less than 0.1% by mass. However, the above other components may not be substantially contained. Furthermore, oxides of light-bearing elements (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) may not be substantially contained.

[0123] Furthermore, glass composition A and glass composition B may contain at least one additive selected from SO, Br, I, SnO, AsO, and SbO, each in a content of 0% by mass or more and 1% by mass or less. The allowable content of each of these components may be less than 0.5% by mass, less than 0.2% by mass, or even less than 0.1% by mass. The allowable total content of these components may be 1% by mass or less, less than 0.5%, less than 0.2%, or even less than 0.1% by mass. However, the above other components may not be substantially present.

[0124] Glass composition A and glass composition B may contain HO, OH, H, CO, CO, He, Ne, Ar, and N, each at a content of 0% by mass or more and 0.1% by mass or less. The allowable content of each of these components may be less than 0.05% by mass, less than 0.03% by mass, or even less than 0.01% by mass. The allowable total content of these components may be 0.1% by mass or less, less than 0.05% by mass, less than 0.03% by mass, or even less than 0.01% by mass. However, the above other components may not be substantially present.

[0125] Glass composition A and glass composition B may contain trace amounts of precious metal elements. For example, precious metal elements such as Pt, Rh, Au, and Os may be contained in a content of 0% by mass or more and 0.1% by mass or less, respectively. The allowable content of each of these components may be less than 0.1% by mass, less than 0.05% by mass, less than 0.03% by mass, or even less than 0.01% by mass. The allowable total content of these components may be 0.1% by mass or less, less than 0.05% by mass, less than 0.03% by mass, or even less than 0.01% by mass. However, the other components may not be substantially present.

[0126] Glass composition A and glass composition B may be compositions that are substantially free of CuO. Glass composition A and glass composition B may be compositions that are substantially free of CoO. Glass composition A and glass composition B may be compositions that are substantially free of PbO. Glass composition A and glass composition B may be compositions that are substantially free of NiO.

[0127] <Characteristics> The characteristics that the glass of the present invention can have are described below. (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 is the temperature most suitable for forming the glass. When producing glass fibers, if the working temperature of the glass is 1100°C or higher, the variation in glass fiber diameter can be reduced. If the working temperature is 1300°C or lower, the fuel cost for melting the glass can be reduced, glass manufacturing equipment is less susceptible to thermal corrosion, and the equipment life can be extended. The lower limit of the working temperature can be 1100°C or higher, and can also be 1120°C or higher, 1140°C or higher, 1150°C or higher, 1160°C or higher, 1170°C or higher, 1180°C or higher, or even 1200°C or higher. The upper limit of the working temperature may be 1300°C or less, 1280°C or less, 1270°C or less, 1260°C or less, or even 1250°C or less.

[0128] The larger the temperature difference ΔT obtained by subtracting the devitrification temperature from the working temperature, the less likely devitrification occurs during glass molding, and the higher the yield of homogeneous glass that can be produced. Therefore, ΔT of glass composition A can be 0°C or higher, 10°C or higher, 20°C or higher, 30°C or higher, 40°C or higher, or even 50°C or higher. On the other hand, if ΔT is 200°C or lower, adjustment of the glass composition becomes easier. ΔT of glass composition A can be 200°C or lower, 180°C or lower, or even 160°C or lower.

[0129] (Young's modulus) The higher the Young's modulus of the glass composition forming the glass fiber, the better the elasticity of the glass fiber, and the improved mechanical properties of the heat insulating material or sound absorbing material made of the glass fiber. Here, the Young's modulus (GPa) can be determined by measuring the longitudinal wave velocity and shear wave velocity of the elastic wave propagating through the glass by a conventional ultrasonic method, and separately measuring the density of the glass by the Archimedes method. The lower limit of this Young's modulus can be 77 GPa or more, 78 GPa or more, 79 GPa or more, or even 80 GPa or more. The upper limit of the Young's modulus can be preferably 100 GPa or less, 99 GPa or less, 98 GPa or less, 97 GPa or less, 96 GPa or less, or even 95 GPa or less.

[0130] (Glass Transition Temperature) The higher the glass transition temperature (glass transition point, Tg) of a glass composition, the higher its heat resistance and the less likely it is to deform during processing involving high-temperature heating. If the glass transition temperature is 560°C or higher, there is little risk of the glass wool changing shape in the event of a fire or the like. With the glass composition specified in this embodiment, glass having a glass transition temperature of 560°C or higher can be easily obtained. The glass transition temperature of the glass composition is preferably 560°C or higher, more preferably 570°C or higher, and even more preferably 580°C or higher. The glass transition temperature may be 600°C or higher, 620°C or higher, 650°C or higher, 680°C or higher, 700°C or higher, 720°C or higher, or in some cases 740°C or higher. The upper limit of the glass transition temperature is preferably about 800°C, and more preferably 780°C or lower.

[0131] (Chemical Durability) Acid resistance and water resistance are suitable indicators of chemical durability in applications as thermal insulation and / or sound absorption materials. The mass loss rate ΔW1, described below, is used as an indicator of acid resistance, with a smaller ΔW1 indicating higher acid resistance. Furthermore, the mass loss rate ΔW2, described below, is used as an indicator of water resistance, with a smaller ΔW2 indicating higher water resistance. When glass fibers are used as thermal insulation materials or sound absorption materials, ΔW1 is preferably 5.0% by mass or less. Therefore, ΔW1 of the glass may be 5.0% by mass or less, or may be 4.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, 1.5% by mass or less, 1.2% by mass or less, 1.0% by mass or less, 0.9% by mass or less, 0.8% by mass or less, 0.7% by mass or less, 0.6% by mass or less, 0.5% by mass or less, 0.4% by mass or less, 0.3% by mass or less, or 0.2% by mass or less. ΔW1 that can be achieved by this embodiment is, for example, 0.01 to 5.0 mass %.

[0132] When glass fibers are used for thermal insulation, sound absorption, or the like, ΔW of the glass fibers is preferably less than 0.50 mass%. ΔW of the glass composition of this embodiment can be less than 0.50 mass%, or can be 0.45 mass% or less, 0.40 mass% or less, 0.35 mass% or less, 0.30 mass% or less, 0.25 mass% or less, or 0.20 mass% or less. ΔW that can be achieved by this embodiment is, for example, 0.01 mass% or more and less than 0.50 mass%.

[0133] <Glass Fiber> The glass fiber of this embodiment is composed of the glass composition described above. The glass fiber of this embodiment may be either long glass fiber or short glass fiber. Long glass fiber is produced by causing a viscosity-controlled glass melt to flow out of a nozzle and winding it up with a winder. This continuous fiber is cut to an appropriate length when used. Short glass fiber is produced by blowing off the glass melt with high-pressure air, centrifugal force, or the like. Short glass fiber is sometimes called glass wool because it has a cotton-like form.

[0134] The average fiber diameter of the glass fibers is, for example, 0.1 to 50 μm. The average fiber diameter of the 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 long glass 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 short glass 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.

[0135] <Glass wool> The glass wool of this embodiment contains the above-described glass fibers. The glass wool of this embodiment is, for example, an aggregate of the above-described short glass fibers containing voids therein, and can have various shapes depending on the area of ​​use, such as a block, a flat plate, a curved plate, a corrugated plate, or a cylindrical shape. The glass wool of this embodiment can have high chemical durability. Therefore, the glass wool of this embodiment can stably maintain its properties as a heat insulating material and / or sound absorbing material for a long period of time even in areas where water such as rainwater may penetrate, or in areas in highly acidic environments such as in chemical plants.

[0136] Hereinafter, the embodiments of the present invention will be described in more detail with reference to Examples and Comparative Examples. (Examples and Comparative Examples) Conventional glass raw materials such as silica sand were mixed to obtain the compositions shown in Tables 1 to 7, and batches of glass raw materials were prepared for each Example and Comparative Example. Each batch was heated to 1500 to 1600°C using an electric furnace to melt it, and maintained in this state for approximately 4 hours until the composition became uniform. Thereafter, a portion of the molten glass (glass melt) was poured onto an iron plate and slowly cooled to room temperature in the electric furnace to obtain a bulk glass composition (plate-shaped product, glass sample).

[0137] The evaluation methods for the properties are described below. (Glass Transition Temperature) The thermal expansion coefficient of the obtained glass composition was measured using a commercially available dilatometer (Rigaku Corporation, Thermomechanical Analyzer, TMA8510), and the glass transition temperature was determined from the thermal expansion curve.

[0138] (Working Temperature) The relationship between viscosity and temperature of the obtained glass composition was investigated by a conventional platinum sphere pulling method, and the working temperature was determined from the results. Here, the platinum sphere pulling method is a method of measuring viscosity by applying the relationship between the load (resistance) applied when immersing a platinum sphere in molten glass and pulling up the platinum sphere at a uniform speed, and the gravity and buoyancy acting on the platinum sphere, to Stokes' law, which shows the relationship between the viscosity and the falling speed when microparticles settle in a fluid.

[0139] (Devitrification Temperature) A glass composition pulverized to particle diameters of 1.0 to 2.8 mm was placed in a platinum boat and held for 2 hours in an electric furnace equipped with a temperature gradient (800 to 1400°C). The devitrification temperature was determined from the maximum temperature of the electric furnace corresponding to the position where crystals appeared. When the glass became cloudy and crystals could not be observed, the maximum temperature of the electric furnace corresponding to the position where cloudiness appeared was taken as the devitrification temperature. Here, the particle diameter is a value measured by a sieving method. Note that the temperature (temperature distribution within the electric furnace), which varies depending on the location within the electric furnace, was measured in advance, and the glass composition placed in a predetermined location within the electric furnace was heated at the temperature of the predetermined location measured in advance. The temperature difference ΔT is the temperature difference obtained by subtracting the devitrification temperature from the working temperature.

[0140] (Young's modulus) Young's modulus E is calculated by the longitudinal wave velocity v of the elastic wave propagating through the glass using a conventional ultrasonic method. l and shear wave velocity v t From the density ρ of the glass measured separately by Archimedes' method, E = 3ρ v t 2 ・(v l 2 -4 / 3・v t 2 ) / (v l 2 -v t 2 ) was calculated using the formula:

[0141] (Tensile Modulus) A glass fiber (filament) was produced using the obtained glass composition (bulk). That is, the glass composition (bulk) was remelted in an electric furnace and then formed into pellets while cooling. A glass fiber having a diameter of 15 μm was produced using these pellets. The tensile modulus of the obtained glass fiber was measured by a method in accordance with "Test method for tensile properties of carbon fiber single fiber R7606:2000" of the Japanese Industrial Standards (JIS).

[0142] (Chemical Durability) Glass filaments were prepared using the obtained glass composition (bulk). Specifically, the glass composition (bulk) was remelted in an electric furnace and then cooled and molded into pellets. These pellets were used to prepare glass filaments with a diameter of 15 μm. Acid Resistance: Glass filaments with a diameter of 15 μm were cut into lengths of 20 mm, and a weight equivalent to the specific gravity of the glass was taken. The glass fibers were immersed in 100 mL of a 10% by weight aqueous sulfuric acid solution at 80°C for 24 hours. The mass loss rate was determined, and this mass loss rate was designated ΔW1. Water Resistance: Glass filaments with a diameter of 15 μm were cut into lengths of 20 mm, and a weight equivalent to the specific gravity of the glass was taken. The mass loss rate was determined when the glass fibers were immersed in 100 mL of distilled water at 80°C for 24 hours. This mass loss rate was designated ΔW2. The mass loss rate was calculated based on the following formula, where Wa is the mass before immersion and Wb is the mass after immersion. Mass reduction rate (%) = {(Wa-Wb) / Wa}×100

[0143] The results of these measurements are shown in Tables 1 to 7. Note that the glass compositions in the tables are all values ​​expressed in mass %.

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151] From Examples 1 to 75, Young's modulus was 77 to 93 GPa, tensile modulus was 69 to 88 GPa, glass transition temperature was 562 to 782 ° C, working temperature was 1208 to 1297 ° C, temperature difference ΔT (working temperature - devitrification temperature) was 2 to 271 ° C, ΔW1 was 0.16 to 2.61 mass%, and ΔW2 was 0.14 to 0.48 mass%.

[0152] The glass composition of Comparative Example 1 had a plate glass composition, a relatively low glass transition temperature of 553°C, and a relatively large ΔW of 0.50 mass%. The glass composition of Comparative Example 2 had a C-glass composition. C-glass has a relatively low glass transition temperature of 549°C. C-glass has a high content of BO, which raises concerns about its impact on manufacturing equipment.

Claims

1. Glass fibers for thermal insulation and / or sound absorption, Expressed in mass %, 50≦SiO 2 ≦75、 0≦B 2 O 3 ≦4、 5≦Al 2 O 3 ≦15、 5≦CaO≦30, 0≦(L) 2 O+1 2 O+K 2 O)≦20、 A glass fiber comprising a glass composition containing the components:

2. The glass composition has a content of 0≦T-Fe, expressed in mass %. 2 O 3 2. The glass fiber of claim 1, wherein the composition is: However, T-Fe 2 O 3 is Fe 2 O 3 is the total iron oxides converted to

3. The glass composition comprises, in mass %, 50≦SiO 2 ≦67、 0≦B 2 O 3 20 5≦Al 2 O 3 ≦15、 45≦(SiO) 2 -Al 2 Oh 3 )≦57、 1≦MgO≦10, 10≦CaO≦30, 0≦(L) 2 O+1 2 O+K 2 O)≦12、 0≦T-Fe 2 O 3 ≦5、 The glass fiber according to claim 2, comprising the components:

4. The glass composition comprises, in mass %, 50≦SiO 2 ≦67、 0≦B 2 O 3 20 5≦Al 2 O 3 ≦15、 45≦(SiO) 2 -Al 2 Oh 3 )≦57、 1≦MgO≦10, 15≦CaO≦30, 0≦T-Fe 2 O 3 ≦5、 The glass fiber according to claim 3, which contains the components of the formula (I) and is substantially free of alkali metal oxides.

5. The glass composition comprises, in mass %, 57≦SiO 2 ≦67、 0≦B 2 O 3 20 5≦Al 2 O 3 ≦15、 45≦(SiO) 2 -Al 2 Oh 3 )≦57、 1≦MgO≦10, 15≦CaO≦30, 0≦(L) 2 O+1 2 O+K 2 O)≦4、 0≦T-Fe 2 O 3 ≦5、 The glass fiber according to claim 3, comprising the components:

6. The glass composition comprises, in mass %, 50≦SiO 2 ≦67、 0≦B 2 O 3 20 5≦Al 2 O 3 ≦15、 45≦(SiO) 2 -Al 2 Oh 3 )≦57、 1≦MgO≦10, 10≦CaO≦30, 1≦SrO≦15, 0≦(L) 2 O+1 2 O+K 2 O)≦4、 0≦T-Fe 2 O 3 ≦5、 The glass fiber according to claim 3, comprising the components:

7. The glass composition comprises, in mass %, 65<SiO 2 ≦75、 0≦B 2 O 3 20 5≦Al 2 O 3 ≦15、 50<(SiO) 2 -Al 2 Oh 3 )≦60、 1≦MgO≦10, 10≦CaO≦25, 0≦(L) 2 O+1 2 O+K 2 O)≦4、 0≦T-Fe 2 O 3 ≦5、 The glass fiber according to claim 2, comprising the components:

8. The glass composition comprises, in mass %, 60≦SiO 2 ≦75、 0≦B 2 O 3 ≦4、 5≦Al 2 O 3 ≦15、 47≦(SiO) 2 -Al 2 Oh 3 )≦60、 1≦MgO≦10, 10≦CaO≦25, 4<(L- 2 O+1 2 O+K 2 <9、 0≦T-Fe 2 O 3 ≦5、 The glass fiber according to claim 2, comprising the components:

9. The glass composition comprises, in mass %, 60≦SiO 2 ≦75、 0≦B 2 O 3 ≦4、 5≦Al 2 O 3 ≦15、 47≦(SiO) 2 -Al 2 Oh 3 )≦60、 5≦CaO≦20, 6≦Na 2 O≦20、 9≦(L) 2 O+1 2 O+K 2 O)≦20、 0≦T-Fe 2 O 3 ≦5、 The glass fiber according to claim 2, comprising the components:

10. Glass fibers for thermal insulation and / or sound absorption, Expressed in mass %, 50≦SiO 2 ≦75、 0≦B 2 O 3 ≦4、 0.1≦(MgO+CaO)≦20, 9≦(L) 2 O+1 2 O+K 2 O)≦20、 5≦ZrO 2 ≦20、 A glass fiber comprising a glass composition containing the components:

11. The glass composition is B 2 O 3 The glass fiber according to claim 1 or 10, which is substantially free of

12. The glass composition comprises, in mass %, 55≦SiO 2 ≦67、 0.1≦B 2 O 3 20 5≦Al 2 O 3 ≦15、 45≦(SiO) 2 -Al 2 Oh 3 )≦57、 1≦MgO≦10, 15≦CaO≦30, 0≦(L) 2 O+1 2 O+K 2 O)≦4、 0≦T-Fe 2 O 3 ≦5、 The glass fiber according to claim 3, comprising the components:

13. 11. The glass fiber according to claim 1, wherein the working temperature is 1300°C or less, when the temperature at which the viscosity of the glass composition is 1000 dPa·sec is defined as the working temperature.

14. 11. The glass fiber according to claim 1, wherein, when a temperature at which the viscosity of the glass composition is 1000 dPa·sec is defined as a working temperature, a temperature difference ΔT obtained by subtracting a devitrification temperature from the working temperature is 0°C or more.

15. ΔW of the glass composition 1 The glass fiber according to claim 1 or 10, wherein the content of the SiO 2 is 0.01 to 1.5 mass%. Here, the ΔW 1 is the mass loss rate when a group of glass single fibers having a diameter of 15 μm and a length of 20 mm and made of the glass composition, whose mass is set to the same value in grams as the specific gravity of the glass composition, is immersed in 100 mL of a 10 mass % aqueous sulfuric acid solution at 80° C. for 24 hours.

16. ΔW of the glass composition 2 The glass fiber according to claim 1 or 10, wherein the content of the SiO2 is 0.01 to 0.5 mass%. Here, the ΔW 2 is the mass loss rate when a group of glass monofilaments made of the glass composition and having a diameter of 15 μm and a length of 20 mm, the mass of which is set to the same value in grams as the specific gravity of the glass composition, is immersed in 100 mL of distilled water at 80° C. for 24 hours.

17. The glass fiber according to claim 1 or 10, wherein the glass composition has a glass transition temperature of 560 to 800°C.

18. The glass fiber according to claim 1 or 10, wherein the Young's modulus of the glass composition is 77 to 100 GPa.

19. The glass fiber according to claim 1 or 10, wherein a glass single fiber made of the glass composition and having a diameter of 15 μm has a tensile modulus of 69 to 88 GPa when measured by a method in accordance with "Test method for tensile properties of carbon fiber single fiber R7606:2000" of the Japanese Industrial Standards (JIS).

20. Glass wool as a heat insulating material and / or sound absorbing material, comprising the glass fiber according to claim 1 or 10.