Fiberglass composition for higher modulus

Abstract

To provide: a glass composition with a moderately high elastic modulus and a low fiberizing temperature, while having a lower manufacturing cost than high-modulus glass compositions; a glass fiber; and a method of forming a continuous glass fiber.SOLUTION: A glass composition is provided which includes about 57.0 to 62.0 mass% of SiO2, about 20.0 to 25.0 mass% of Al2O3, about 8.0 to 12.5 mass% of MgO, about 7 to 9.0 mass% of CaO, about 0.4 to 1.0 mass% of Li2O, 0.0 to about 1.0 mass% of Na2O, about 0 to 0.5 mass% of K2O; and 0.2 to about 1.5 mass% of TiO2. The glass composition has a fiberizing temperature of about 1,300°C or less. Such applications include nonwoven fabrics for use in forming wind blades and aerospace structures.SELECTED DRAWING: None

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the full benefit of U.S. Provisional Patent Application No. 62 / 956,422, filed January 2, 2020, the entire disclosure of which is incorporated herein by reference. [Background technology]

[0002] Glass fibers are generally produced from various raw materials, called a "glass batch," combined in specific proportions to achieve a desired composition. The glass batch can be melted in a melting apparatus, and the molten glass is drawn through a bushing or orifice plate into filaments (the resulting filaments are also called continuous glass fibers). A sizing composition containing a lubricant, a coupling agent, and a film-forming binder resin can then be applied to the filaments. After sizing, the fibers can be collected into one or more strands and wound into a package, or the fibers can be chopped and collected while wet. The collected chopped strands can then be dried and cured to form dry chopped fibers, or they can be packaged in their wet state as wet chopped fibers.

[0003] The composition of glass batches, and the fiberglass produced therefrom, is often expressed in terms of the oxides contained therein, and those oxides are generally SiO 2、 These include Al2O3, CaO, MgO, B2O3, Na2O, K2O, Fe2O3, TiO2, Li2O, etc. By varying the amounts of these oxides or removing some of the oxides in the glass batch, many types of glasses can be produced. Such glasses that can be produced include R-glass, E-glass, S-glass, A-glass, C-glass, and ECR-glass. The glass composition controls the glass formation and product properties. Other characteristics of the glass composition include raw material cost and environmental impact. For example, E-glass is an aluminoborosilicate glass, generally alkali-free, commonly used in electrical applications. One advantage of E-glass is that its liquidus temperature allows for operating temperatures of approximately 1900°F to 2400°F (1038°C to 1316°C) for producing glass fibers. The ASTM classification for E-glass fiber yarns, used in printed circuit boards and aerospace applications, defines the composition as 52-56% by weight SiO2, 16-25% by weight CaO, 12-16% by weight Al2O3, 5-10% by weight B2O3, 0-5% by weight MgO, 0-2% by weight Na2O and K2O, 0-0.8% by weight TiO2, 0.05-0.4% by weight Fe2O3, and 0-1.0% by weight fluorine.

[0004] Boron-free fibers are sold under the trademark ADVANTEX® (Owens Corning, Toledo, Ohio, USA). Boron-free fibers, such as those disclosed in U.S. Pat. No. 5,789,329, the entire contents of which are incorporated herein by reference, offer significant improvements in operating temperatures over boron-containing E-glass. Boron-free glass fibers meet the ASTM definition for E-glass fibers for general-purpose applications. R-glass is a family of glasses composed primarily of oxides of silicon, aluminum, magnesium, and calcium, with a chemical composition that produces glass fibers with higher mechanical strength than E-glass fibers. R-glass has a composition containing about 58 to about 60 wt. % SiO2, about 23.5 to about 25.5 wt. % Al2O3, about 14 to about 17 wt. % CaO and MgO, and less than about 2 wt. % miscellaneous components. R-glass contains more alumina and silica than E-glass, necessitating higher melting and processing temperatures during fiber formation. Typically, the melting and processing temperatures for R-glass are higher than those for E-glass. These higher processing temperatures necessitate the use of expensive platinum-wire-lined melting equipment. Furthermore, for R-glass to approach the liquidus temperature near the forming temperature, the glass must be fiberized at a lower viscosity than E-glass, which is conventionally fiberized at or near about 1000 poise. Fiberizing R-glass at conventional 1000 poise viscosities will likely result in devitrification of the glass, which will cause process interruptions and reduced productivity.

[0005] High-performance glass fibers have higher strength and stiffness compared to traditional E-glass fibers. Stiffness is especially important for modeling and performance in some products. For example, in power-generating wind stations, composites prepared from glass fibers with good stiffness properties, such as wind turbine blades, allow for longer blade lengths while maintaining wind blade deflection within acceptable limits. Elastic modulus (interchangeably known as "Young's modulus") is a measure of fiber stiffness and defines the relationship between the stress applied to a material and the strain produced by that same material. A stiff material has a high elastic modulus and changes its shape only slightly under elastic load. A soft material has a low elastic modulus and changes its shape considerably.

[0006] Various types of high-performance glass compositions have been developed, often attempting to maximize modulus and tensile strength. However, increasing the modulus of glass fibers beyond a certain point (i.e., above 92 GPa) can lengthen the molds for composite wind blades, necessitating the creation of new molds. Achieving a moderate modulus compatible with current composite molds while maintaining low fiberization temperatures would be beneficial and cost-effective. Fiberization temperatures below approximately 1,300°C allow the use of most current state-of-the-art materials and techniques for glass fiber production, thus enabling compatibility with established manufacturing facilities. Furthermore, similar fiberization temperatures to other already-produced glass compositions allow for rapid operation, switching furnaces from producing one type of glass to another without the need to change molding techniques. Lower fiberization temperatures are superior from the perspective of energy use and also from the perspective of platinum volatilization. Platinum volatilizes more rapidly at higher temperatures, reducing the lifespan of molding techniques.

[0007] Manufacturers of wind turbine blades make large investments in creating the molds used to form wind blades. Furthermore, wind blades can be so large that entire plants are built around the production of blades of a particular size. While the goal is generally to maintain an increased modulus of elasticity in the glass fiber to allow for the production of longer blades, it is still desirable to make the best possible use of existing molds and facilities. To do this, the glass fiber must provide properties within a performance range. If the modulus of elasticity of the glass is too good, ethically, new molds must be created to take advantage of the higher performance. These fibers allow for a higher tolerance for manufacturing imperfections in these same molds. Therefore, it is desirable to optimize performance without necessarily increasing the size of the wind blade. There is a need in the art for high performance glass compositions that have acceptable forming properties, such as having a sufficiently low fiberization temperature, while achieving a moderate, but not too high, modulus of elasticity, such as between 90 and 92 GPa. Summary of the Invention

[0008] Various exemplary embodiments of the present concept are directed to a glass composition comprising, expressed as mass percentages relative to the mass of the total composition, SiO in an amount of 57.0-62.0 wt. %, AlO in an amount of 20.0-25.0 wt. %, CaO in an amount of 7.0-9.0 wt. %, MgO in an amount of 8.0-12.5 wt. %, NaO in an amount of 0-1.0 wt. %, KO in an amount of 0-0.5 wt. %, LiO in an amount of 0.4-1.0 wt. %, and TiO in an amount of 0.2-1.5 wt. The mass percentage (R1) (MgO + AlO) / (SiO + CaO) is at least 0.47, and the mass percentage ratio (R3) (MgO / SiO) is at least 0.19. The glass composition has a fiberization temperature of no more than 1,300°C.

[0009] In any of the various embodiments, the total amount of SiO2, Al2O3, MgO, and CaO can be at least 98% by weight and less than 99.5% by weight. In any of the various embodiments, the composition comprises from 57.1% to less than 59% by weight of SiO2. In any of the various embodiments, the composition comprises 7.9% to less than 9.0% by weight CaO. In any of the various embodiments, the composition comprises greater than 20% to 21% by weight Al2O3. In any of the various embodiments, the composition includes 0.45% to 0.8% by weight of Li2O. In any of the various embodiments, the glass composition does not include rare earth oxides. In any of the various embodiments, the composition is essentially free of B2O3. In any of the various embodiments, the composition comprises 0.1 to 0.8 wt. % Na2O. In any of the various embodiments, the composition comprises a weight percent ratio (R2) (MgO+Al2O3+Li2O) / (CaO+SiO2+Na2O+K2O) greater than 0.46.

[0010] Further exemplary aspects of the present inventive concept are directed to glass compositions comprising SiO in an amount of 58.0-6.20 wt.%, AlO in an amount of 20.0-25.0 wt.%, CaO in an amount of 7.9-12.0 wt.%, MgO in an amount of 8.0-12.5 wt.%, NaO in an amount of 0-1.0 wt.%, KO in an amount of 0-0.5 wt.%, LiO in an amount of 0.4-1.0 wt.%, and TiO in an amount of 0.2-1.5 wt.%. In various exemplary embodiments, the compositions comprise a mass percent ratio (R) (MgO + AlO + LiO) / (CaO + SiO + NaO + KO) greater than 0.46, and a mass percent ratio (R) (MgO / SiO) of at least 0.19. In some embodiments, the glass compositions have a fiberization temperature of no more than 1,300°C.

[0011] In any of the various embodiments, the total amount of SiO2, Al2O3, MgO, and CaO can be at least 98% by weight and less than 99.5% by weight. In any of the various embodiments, the composition comprises from 57.1% to less than 59% by weight of SiO2. In any of the various embodiments, the composition comprises 7.9% to less than 9.0% by weight CaO. In any of the various embodiments, the composition comprises greater than 20% to 21% by weight Al2O3. In any of the various embodiments, the composition includes 0.45% to 0.8% by weight of Li2O. In any of the various embodiments, the glass composition does not include rare earth oxides. In any of the various embodiments, the composition is essentially free of B2O3. In any of the various embodiments, the composition comprises 0.1 to 0.8 wt. % Na2O. In any of the various embodiments, the composition comprises a weight percent ratio (R1) (MgO+Al2O3) / (SiO2+CaO) that is at least 0.47.

[0012] A further exemplary embodiment of the inventive concept is directed to a glass fiber formed from a glass composition comprising SiO in an amount of 57.0-62.0 wt. %, AlO in an amount of 20.0-25.0 wt. %, CaO in an amount of 7-9.0 wt. %, MgO in an amount of 8.0-12.5 wt. %, NaO in an amount of 0-1.0 wt. %, KO in an amount of 0-0.5 wt. %, LiO in an amount of 0.4-1.0 wt. %, and TiO in an amount of 0.2-1.5 wt. The glass composition has a mass percent ratio (R1) (MgO + AlO) / (SiO + CaO) of at least 0.47 and a mass percent ratio (R3) (MgO / SiO) of at least 0.19. The glass composition has a fiberization temperature of no more than 1,300°C, and the glass fiber has an elastic modulus between 90 GPa and 92 GPa. In any of the various embodiments, the glass fibers have a fiber density of at least 2.6 g / cm 3 It has a density such that

[0013] A further exemplary aspect of the inventive concept is directed to a method of forming a continuous glass fiber, comprising providing a molten composition according to any of the exemplary embodiments disclosed herein and drawing the molten composition through an orifice to form a continuous glass fiber. A further exemplary aspect of the inventive concept is directed to a reinforced composite product comprising a polymer matrix and a plurality of glass fibers formed from a glass composition comprising SiO in an amount of 57.0-62.0 wt.%, AlO in an amount of 20.0-25.0 wt.%, CaO in an amount of 7-9.0 wt.%, MgO in an amount of 8.0-12.5 wt.%, NaO in an amount of 0-1.0 wt.%, KO in an amount of 0-0.5 wt.%, LiO in an amount of 0.4-1.0 wt.%, and TiO in an amount of 0.2-1.5 wt.%. In some exemplary embodiments, the glass composition has a mass percent ratio (R1) (MgO + AlO) / (SiO + CaO) of at least 0.47 and a mass percent ratio (R3) (MgO / SiO) of at least 0.19. The glass composition has a fiberization temperature of only 1,300° C. or less, and the glass fiber has an elastic modulus between 90 GPa and 92 GPa. The above and other objects, features and advantages of the present invention will become more fully apparent hereinafter from a consideration of the detailed description that follows. DETAILED DESCRIPTION OF THE INVENTION

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which these exemplary embodiments belong. The terminology used in the description herein is merely for the purpose of describing the exemplary embodiments and is not intended to limit the exemplary embodiments. Thus, the general inventive concept is not intended to be limited to the specific embodiments exemplified herein. Although other methods and materials similar or equivalent to those described herein can be used to practice or test the present invention, the preferred methods and materials are described herein. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0015] "Substantially free" means that the composition contains less than 1.0% by weight of the recited component, including 0.8% by weight or less, 0.6% by weight or less, 0.4% by weight or less, 0.2% by weight or less, 0.1% by weight or less, and 0.05% by weight or less. In any of the exemplary embodiments, "substantially free" means that the composition contains 0.01% by weight or less of the recited component.

[0016] Unless otherwise indicated, all numbers expressing quantities of ingredients, chemical and molecular properties, reaction conditions, and the like used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless specifically indicated to the contrary, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by exemplary embodiments of the present invention. At the very least, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches. Unless otherwise indicated, any element, property, feature, or combination of elements, properties, and features can be used in any embodiment disclosed herein, regardless of whether that element, property, feature, or combination of elements, properties, and features is explicitly disclosed in that embodiment. It will be readily understood that features described with respect to any particular aspect described herein may be applicable to other aspects described herein, provided that those features are compatible with that aspect. In particular: features described herein with respect to the method may be applicable to glass fiber products, and vice versa; features described herein with respect to the method may be applicable to glass compositions, and vice versa; and features described herein with respect to the glass fibers may be applicable to glass compositions, and vice versa.

[0017] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the exemplary embodiments are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Every numerical range given throughout this specification and the claims includes every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein. Furthermore, every numerical value reported in the examples can be used to define either the upper or lower endpoints of the broader compositional ranges disclosed herein.

[0018] The present disclosure relates to glass compositions that have a reasonably high modulus and a low fiberization temperature while costing less than conventional high modulus glass compositions. The glass compositions disclosed herein are suitable for melting in conventional, commercially available refractory-lined glass furnaces widely used in the manufacture of glass reinforcing fibers. The glass composition may be in a molten form obtainable by melting the components of the glass composition in a melting apparatus. The glass composition exhibits a low fiberization temperature, defined as the temperature corresponding to a melt viscosity of about 1000 poise, as determined by ASTM C965-96(2007). A reduced fiberization temperature can reduce the cost of producing glass fibers, since it allows for longer bushing life and a reduced amount of energy required to melt the components of the glass composition. Thus, the energy released is generally less than the energy required to melt many commercially available glass formulations. This lower energy requirement can also reduce the overall manufacturing costs associated with the glass composition.

[0019] For example, at lower fiberization temperatures, the bushing may be operated at cooler temperatures and therefore will not "sag" as quickly as is typically observed. "Sag" is a phenomenon that occurs when a bushing held at high temperatures for an extended period of time loses its intended stability. Therefore, by lowering the fiberization temperature, the bushing's sag rate can be reduced, maximizing bushing life. Furthermore, a lower fiberization temperature is better from an energy usage perspective and also slows platinum volatilization.

[0020] In any of the exemplary embodiments, the glass composition can have a fiberization temperature of less than 2,372°F (1,300°C), including fiberization temperatures of 2,363°F (1,295°C) or less, 2,354°F (1,290°C) or less, 2,345°F (1,285°C) or less, and 2,336°F (1,280°C) or less. In any of the exemplary embodiments, the glass composition can have a fiberization temperature between 2,330°F (1,276.76°C) and 2,366.6°F (1,297°C), or between 2,345°F (1,285°C) and 2,357.6°F (1,292°C). Another fiberizing property of a glass composition is the liquidus temperature. The liquidus temperature is defined as the highest temperature at which equilibrium exists between the liquid glass and its primary crystalline phase. The liquidus temperature can be measured by exposing the glass composition to a temperature gradient in a platinum alloy boat for 16 hours (ASTM C829-81(2005)). At all temperatures above the liquidus temperature, the glass is completely molten, i.e., contains no crystals. At temperatures below the liquidus temperature, crystals may form. In any of the exemplary embodiments, the glass composition can have a liquidus temperature of less than 2,350°F, including liquidus temperatures of 2,300°F (1,221.11°C) or less, 2,250°F (1,232.22°C) or less, 2,232°F (1,222.22°C) or less, 2,225°F (1,218.33°C) or less, and 2,220°F (1,215.56°C) or less. In any of the exemplary embodiments, the glass composition can have a liquidus temperature between 2,200°F (1,204.44°C) and 2,300°F (1,221.11°C), or between 2,210°F (1,210°C) and 2,235°F (1,223.89°C).

[0021] The third fiberization property is "ΔT," also known as delta T, which is defined as the difference between the fiberization temperature and the liquidus temperature. If ΔT is too small, the molten glass may crystallize in the fiberizer, causing a disruption to the production process. It is desirable for ΔT to be as large as possible for a given forming viscosity, as this allows for a greater degree of plasticity during fiberization and helps avoid devitrification in both the glass distribution system and the fiberizer. A large ΔT further reduces the cost of producing glass fiber by enabling longer bushing life and a less sensitive forming process. In any of the exemplary embodiments, the glass composition can have a ΔT of at least 40° C., including at least 55° C., at least 60° C., at least 70° C., at least 75° C., at least 80° C., and at least 90° C. In various exemplary embodiments, the glass composition has a ΔT between 40° C. and 90° C., including between 50° C. and 85° C., and between 70° C. and 80° C.

[0022] The glass composition may contain approximately 56.0 to approximately 62.0% by mass of SiO2, approximately 17.0 to approximately 24.0% by mass of Al2O3, approximately 9.0 to approximately 13.0% by mass of MgO, approximately 7.0 to approximately 11.0% by mass of CaO, approximately 0.0 to approximately 1.0% by mass of Na2O, 0 to approximately 2.0% by mass of TiO2, 0 to approximately 1.5% by mass of Fe2O3, and approximately 0.2% to approximately 1.0% by mass of Li2O. Advantageously, the ratio of the weight percent of the combined alumina oxide and magnesium oxide to the weight percent of the combined silicon dioxide and calcium oxide (R1) (MgO + Al2O3) / (SiO2 + CaO) is at least 0.47, such as at least 0.48 and at least 0.49. An R1 ratio of at least 0.47 ensures that the resulting fiberglass demonstrates a sufficiently high modulus of elasticity. In some exemplary embodiments, the ratio of the combined weight percent of MgO, AlO, and LiO to the combined weight percent of CaO, SiO, NaO, and KO (R)(MgO+AlO+LiO) / (CaO+SiO+NaO+KO) is greater than 0.46, including at least 0.47, at least 0.48, at least 0.49, and at least 0.50. In any of the exemplary embodiments, the ratio of the weight percent of MgO to the weight percent of SiO2 (R3) is greater than 0.175, such as greater than 0.18, greater than 0.19, or greater than 0.20.

[0023] Although the glass compositions of the subject invention may include any combination of R1, R2, and R3, glass compositions satisfying each of the presented ratios have sufficiently high modulus, specific modulus, and ΔT without fiberization temperatures exceeding 1,300° C. These ratios also result in significant increases in intrinsic tensile strength. The glass composition comprises at least 57 wt.% but not more than 62 wt.% SiO. In some exemplary embodiments, the glass composition comprises 57.1 wt.% or more SiO, including 57.25 wt.% or more, 57.3 wt.% or more, 57.5 wt.% or more, 57.7 wt.% or more, and 58.0 wt.% or more SiO. In some exemplary embodiments, the glass composition comprises 60.5 wt.% or less SiO, including 60.3 wt.% or less, 60.2 wt.% or less, 60 wt.% or less, 59.8 wt.% or less, and 59.5 wt.% or less SiO. In some exemplary embodiments, the glass composition comprises 57.15 wt.% to less than 59 wt.% SiO.

[0024] To achieve both desirable mechanical and fiberization properties, one important aspect of the glass composition is an Al2O3 concentration of at least 19.0 wt.% and no more than 25.0 wt.%. Including less than 19.0 wt.% Al2O3 contributes to the formation of glass fibers with disadvantageously low moduli. In some exemplary embodiments, the glass composition includes at least 19.5 wt.% Al2O3, including at least 19.7 wt.%, at least 20.0 wt.%, at least 20.05 wt.%, at least 20.1 wt.%, and at least 20.3 wt.%. In some exemplary embodiments, the glass composition includes no more than 22.0 wt.% Al2O3, including no more than 21.8 wt.%, no more than 21.6 wt.%, no more than 21.2 wt.%, no more than 21.1 wt.%, and no more than 21.0 wt.%. In any of the exemplary embodiments, the glass composition includes between 20.0 wt.% and no more than 21.0 wt.% Al2O3. The inclusion of higher levels of Al2O3 increases the tendency to crystallize.

[0025] The glass composition advantageously includes at least 8.0% by weight and no more than 15.0% by weight of MgO. Including more than 15.0% by weight of MgO induces an increase in the liquidus temperature, which in turn increases the crystallization tendency of the glass. Including less than 8.0% by weight results in glass fibers with disadvantageously low modulus when replaced with CaO and disadvantageously increased viscosity when replaced with SiO. In any of the exemplary embodiments, the glass composition can include at least 9.5% by weight of MgO, including at least 10.0%, at least 10.5%, at least 11.0%, at least 11.10%, and at least 11.50% by weight of MgO. In any of the exemplary embodiments, the glass composition can include no more than 12.5% ​​by weight of MgO, such as no more than 12.0%, no more than 11.9%, or no more than 11.8% by weight. In any of the exemplary embodiments, the glass composition can include 10.5% to less than 12.0% by weight MgO.

[0026] The present glass compositions advantageously include at least 7.0 wt.% and no more than 12.0 wt.% CaO. Including more than 12.0 wt.% CaO results in a glass with a low elastic modulus. Including less than 7.0 wt.% CaO can adversely increase either the liquidus temperature or the viscosity, depending on which oxide the CaO substitutes for. In any of the exemplary embodiments, the present glass compositions can include at least 7.15 wt.% CaO, including at least 7.4 wt.%, at least 7.7 wt.%, at least 8.0 wt.%, and at least 8.2 wt.% CaO. In any of the exemplary embodiments, the present glass compositions can include no more than 11.5 wt.% CaO, such as no more than 10.0 wt.%, no more than 9.8 wt.%, no more than 9.5 wt.%, and no more than 9.0 wt.% CaO. In any of the exemplary embodiments, the present glass compositions can include a CaO concentration between 7.9 wt.% and less than 9.0 wt.%. In any of the exemplary embodiments, the combined amount of SiO2, Al2O3, MgO, and CaO can be at least 98.0% by weight, or at least 99% by weight and not more than 99.5% by weight. In any of the exemplary embodiments, the combined amount of SiO2, Al2O3, MgO, and CaO can be between 97.5% and less than 99.5% by weight, such as between 98.0% and less than 99.0% by weight and between 98.05% and 98.8% by weight.

[0027] The present glass compositions include Li2O in an amount of from about 0.1% by weight to a maximum of about 2.0% by weight. The presence of Li2O reduces the fiberization temperature of the glass composition and improves the modulus of glass fibers formed from the glass composition. In any of the exemplary embodiments, the present glass compositions can include from about 0.2% by weight to about 1.0% by weight of Li2O, including from about 0.4% by weight to about 0.8% by weight and from about 0.45% by weight to about 0.7% by weight. In any of the exemplary embodiments, the present glass compositions can include greater than 0.45% by weight to less than 0.8% by weight of Li2O. The glass composition may include up to about 2.0 wt. % TiO. In any of the exemplary embodiments, the glass composition may include from about 0.05 wt. % to about 1.5 wt. % TiO, including from about 0.4 wt. % to about 1.0 wt. % and from about 0.5 wt. % to about 0.7 wt. % TiO. The glass composition may include up to about 2.0 wt.% Fe2O3. In any of the exemplary embodiments, the glass composition may include from about 0.05 wt.% to about 1.0 wt.% Fe2O3, including from about 0.2 wt.% to about 0.8 wt.% and from about 0.3 wt.% to about 0.6 wt.%.

[0028] In any of the exemplary embodiments, the glass composition can include less than 2.0 wt. % of the alkali metal oxides NaO and KO, including between 0 and 1.5 wt. %. The glass composition can advantageously include both NaO and KO in an amount greater than 0.01 wt. % of each oxide. In any of the exemplary embodiments, the glass composition can include about 0 to about 1.0 wt. % NaO, including about 0.01 to about 0.5 wt. %, about 0.03 to about 0.3 wt. %, and 0.04 to about 0.1 wt. %. In any of the exemplary embodiments, the glass composition can include about 0 to about 1 wt. % KO, including about 0.01 to about 0.5 wt. %, about 0.03 to about 0.3 wt. %, and 0.04 to about 0.2 wt. %.

[0029] As used herein, the terms "weight percent," "% by weight," "wt. %," and "percent by weight" may be used interchangeably and are meant to represent a weight percent (or percent by weight) of the total composition.

[0030] The glass compositions of the present invention may be free or substantially free of BO, SrO, and fluorine, although any may be added in small amounts to adjust fiberization and final glass properties and, if maintained below a few percent, do not adversely affect properties. As used herein, substantially free of BO, SrO, and fluorine means that the total amount of BO, SrO, and fluorine present is 1.0 wt.% of the composition. The total amount of BO, SrO, and fluorine present may be less than about 0.5 wt.% of the composition, including less than about 0.2 wt.%, less than about 0.1 wt.%, and less than about 0.05 wt.%.

[0031] The glass composition may further contain impurities and / or trace substances without adversely affecting the glass or fibers. These impurities may be introduced into the glass as raw material impurities or may be products formed by chemical reactions between the molten glass and furnace components. Non-limiting examples of trace substances include zinc, strontium, barium, and combinations thereof. The trace substances may be present in their oxide form and may further include fluorine and / or chlorine. In any of the exemplary embodiments, the glass composition of the present invention may contain less than 1.0 wt. % of each of BaO, SrO, ZnO, ZrO2, PO5, and SO3, including less than 0.5 wt. %, less than 0.2 wt. %, and less than 0.1 wt. %. In particular, the glass compositions may contain less than about 5.0 wt. % BaO, SrO, ZnO, ZrO2, P2O5, and / or SO3 in total, where BaO, SrO, ZnO, ZrO2, P2O5, and SO3 are each present, if at all, in an amount less than 1.0 wt. %.

[0032] In any of the exemplary embodiments, the glass composition may include less than 2.0 wt. % of the following modifying components (collectively): CeO, LiO, FeO, TiO, WO, and BiO. In any of the exemplary embodiments, the glass composition may include less than 1.5 wt. % of the modifying components. In any of the exemplary embodiments, the glass compositions may include less than 1.0 wt. % of the rare earth oxides Y2O3, Ga2O3, Sm2O3, Nd2O3, La2O3, Ce2O3, and Sc2O3 ("R2O3") and Ta2O5, Nb2O5, or V2O5 ("R2O5"), including between 0 and 0.9 wt. % or between 0 and 0.5 wt. %. In some exemplary embodiments, the glass compositions are free of rare earth oxides. As shown above, the glass compositions of the present invention unexpectedly demonstrate a balance between low fiberization temperatures and moderate elastic (Young's) modulus and tensile strength to yield high performance glass fibers for use in current composite mold specifications without the need for such downstream mold reconfiguration.

[0033] The tensile strength of a fiber is also referred to herein simply as "strength." In any of the exemplary embodiments, tensile strength is measured on pristine fibers (i.e., unsized and pristine laboratory-produced fibers) using an Instron tensile testing instrument conforming to ASTM D2343-09. Exemplary glass fibers formed from the glass compositions of the present invention described above can have a fiber tensile strength of at least 4,500 MPa, including at least 4,600 MPa, at least 4,700 MPa, at least 4,800 MPa, at least 4,825 MPa, and at least 4,850 MPa. In any of the exemplary embodiments, glass fibers formed from the compositions described herein can have a fiber tensile strength of from about 4,000 to about 5,000 MPa, including from about 4,350 MPa to about 4,950 MPa, from about 4,400 to about 4,900 MPa. Advantageously, by combining the compositional parameters disclosed herein, it is possible to produce glass fibers having a tensile strength of at least 4,800 MPa, including at least 4,850 MPa, while maintaining desirable fiberization characteristics and a moderate modulus.

[0034] The modulus of elasticity of a glass fiber can be determined by taking the average measurement for five single glass fibers measured in accordance with the sonic measurement procedure outlined in the report "Glass Fiber and Measuring Facilities at the U.S. Naval Ordnance Laboratory," Report Number NOLTR 65-87, June 23, 1965.

[0035] Exemplary glass fibers formed from the glass compositions of the present invention can have a moderately high modulus of elasticity (Young's modulus) between about 90 GPa and about 92 GPa. Maintaining a modulus that is moderate and not greater than 92 GPa is important to ensure that the glass fibers can be used in existing composite molds, thereby providing cost savings over current glass compositions. At moduli greater than 92 GPa, new composite molds may be desirable due to increased composite size, etc. However, a target modulus between 90 and 92 GPa provides improved composite performance within current mold specifications. In any of the exemplary embodiments, the glass fibers formed according to the present application can have a modulus of elasticity of at least 90.5 GPa, such as at least 90.6 GPa, at least 90.8 GPa, at least 91.0 GPa, or at least 91.2 GPa. In any of the exemplary embodiments, the exemplary glass fibers formed from the glass compositions of the present invention can have an elastic modulus of between about 90.2 GPa and about 92 GPa, including between about 90.5 GPa and about 91.9 GPa and between about 90.7 GPa and about 91.8 GPa.

[0036] The modulus of elasticity can then be used to determine the specific modulus. It is desirable to have as high a specific modulus as possible to achieve a lightweight composite material that provides stiffness to the final article. The specific modulus is important in applications where the stiffness of the product is a critical parameter, such as wind energy and aerospace applications. As used herein, the specific modulus is determined by the following formula: Specific modulus (MJ / kg) = Elastic modulus (GPa) / Density (kg / cubic meter) It is calculated by: Exemplary glass fibers formed from the glass compositions of the present invention can have a specific modulus of from about 32.0 MJ / kg to about 37.0 MJ / kg, including from about 33 MJ / kg to about 36 MJ / kg and from about 34.0 MJ / kg to about 35.0 MJ / kg. Density can be measured by any method known and generally accepted in the art, such as the Archimedes method (ASTM C693-93(2008)) for unannealed bulk glass. Glass fibers have a density of about 2.0 to about 3.0 g / cm. 3 In particular, in any of the exemplary embodiments, the glass fibers have a density of about 2.40 to about 2.75 g / cm 3 , about 2.50~2.70g / cm 3 and about 2.60 to about 2.68 g / cm 3 Approximately 2.45 to 2.8 g / cm 3 The density of the granular material may be 0.05 to 0.15.

[0037] In any of the exemplary embodiments, the glass fibers formed from the glass composition of the present invention may have improved corrosion resistance. According to some exemplary embodiments, a method for preparing glass fibers from the above-described glass compositions is provided. The glass fibers can be formed by any means known and traditionally used in the art. The glass fibers are formed by obtaining the crude ingredients and mixing these ingredients in appropriate amounts to provide the desired weight percentage of the final composition. The method can further include providing the glass composition of the present invention in molten form and drawing the molten composition through an orifice in a bushing to form the glass fibers. The mixed batch can then be melted in a furnace or melter, and the resulting molten glass passed along a forehearth and drawn through orifices in a bushing located at the bottom of the forehearth to form individual glass filaments. In some exemplary embodiments, the furnace or melter is a conventional refractory melter. Utilizing a refractory bath formed from refractory blocks can reduce manufacturing costs associated with producing glass fibers produced from the compositions of the present invention. In some exemplary embodiments, the bushing is a platinum alloy-based bushing. The individual filaments can then be gathered together to form glass fiber strands. The fiber strands can be wound up and further processed in a conventional manner suitable for the intended application.

[0038] The operating temperatures of the glass in the melter, forehearth, and bushing may be selected to appropriately adjust the viscosity of the glass and may be maintained using a suitable method, such as a control device. The temperature of the front end of the melter may be automatically controlled to reduce or eliminate devitrification. The molten glass may then be pulled (drawn) through holes or orifices in the bottom or tip plate of the bushing to form a glass fiber. According to some exemplary embodiments, the flow of molten glass through the bushing orifice is attenuated and the strand formed from multiple individual filaments is wound onto a forming tube mounted on a rotatable collet of a winding device, or the glass fiber is chopped at a suitable speed. The glass fiber of the present invention may be obtained by any of the methods described herein or by any known method for forming glass fibers.

[0039] The fibers may be further processed in a conventional manner suitable for the intended application. For example, in some exemplary embodiments, the glass fibers are sized using a sizing composition known to those skilled in the art. The sizing composition is in no way limited and may be any sizing composition suitable for glass fiber applications. The sized fibers can be used to reinforce substrates such as various plastics, where the end use of the product requires high strength and stiffness and low mass. Such applications include, but are not limited to, nonwoven fabrics for use in forming wind blades, reinforced concrete, infrastructure structures such as bridges, and aerospace structures. In this regard, any of the exemplary embodiments of the present invention may include a composite material incorporating the glass fibers of the present invention described above in combination with a curable matrix material, also referred to herein as a reinforced composite product. The matrix material may be any suitable thermoplastic or thermosetting resin known to those skilled in the art, including, but not limited to, thermoplastic resins such as polyester, polypropylene, polyamide, polyethylene terephthalate, and polybutylene, and thermosetting resins such as epoxy resins, unsaturated polyesters, phenolic resins, vinyl esters, and elastomers. These resins may be used alone or in combination. The reinforced composite product may be used to manufacture composites such as wind blades, rebar, pipes, filament windings, muffler fillers, and sound absorbers. According to a further exemplary embodiment, the present invention provides a method for preparing the composite product described above. The method may include combining at least one polymeric matrix material with a plurality of glass fibers. Both the polymeric matrix material and the glass fibers may be as described above. [Example]

[0040] Exemplary glass compositions according to the present invention were prepared by mixing batch components in proportional amounts to achieve the final glass composition with the oxide weight percentages set forth in Tables 1-2 below. The raw materials were melted in platinum crucibles in an electrically heated furnace at a temperature of 1,650°C for 3 hours. Fiberization temperature was measured using the rotating cylinder method described in ASTM C965-96 (2007), entitled "Standard Practice for Measuring Viscosity of Glass Above the Softening Point," the contents of which are incorporated herein by reference. Liquidus temperature was measured by exposing the glass to a temperature gradient in a platinum alloy boat for 16 hours, as specified in ASTM C829-81 (2005), entitled "Standard Practices for Measurement of Liquidus Temperature of Glass," the contents of which are incorporated herein by reference. Density was measured by the Archimedes method, as detailed in ASTM C693-93 (2008), entitled "Standard Test Method for Density of Glass Buoyancy," the contents of which are incorporated herein by reference.

[0041] The specific elastic modulus is calculated by multiplying the measured elastic modulus (Young's modulus) (unit: GPa) by the density (g / cm 3 The calculation was made by dividing by the unit of Tensile strength was measured on the original fiber using an Instron tensile testing instrument according to ASTM D2343-09, entitled "Standard Test Method for Tensile Properties of Glass Fiber Strands, Yarns, and Rovings Used in Reinforced Plastics," the contents of which are incorporated herein by reference.

[0042] [Table 1]

[0043] [Table 2]

[0044] Tables 1 and 2 illustrate the particular balance of moderate modulus (between 90-92 GPa) and good tensile strength, while maintaining fiberization temperatures below 1,300° C., achieved by glass fibers formed according to the concepts of the present invention. In particular, each of the glass compositions in Tables 1 and 2 demonstrates a ratio (R1) (MgO+Al2O3) / (CaO+SiO2) of at least 0.47, a ratio (R2) (MgO+Al2O3+Li2O) / (CaO+SiO2+Na2O+K2O) greater than 0.46, and a ratio (R3) (MgO / SiO2) of at least 0.19.

[0045] In contrast, Table 3 below details comparative examples from European Application No. 10860973.6. As illustrated, the exemplary comparative compositions do not satisfy each of R1, R2, and R3, resulting in fiberization temperatures above 1,300°C and modulus values ​​above 92 GPa. The glass compositions of the present invention balance a moderate modulus (between 90 and less than 92 GPa) and good tensile strength with a low fiberization temperature.

[0046] [Table 3]

[0047] The invention of this application has been described above both generally and with reference to specific embodiments. While the invention has been described in what are considered to be the preferred embodiments, a wide variety of alternatives known to those skilled in the art can be selected within the scope of the generic disclosure. The invention is not particularly limited except as recited in the claims set forth below.

Claims

1. SiO in an amount of 57.0 to 62.0% by weight 2 , Al in an amount of 20.0 to 25.0% by weight 2 O 3 , CaO in an amount of 7.0 to 9.0% by weight, MgO in an amount of 8.0 to 12.5% ​​by weight, Na in an amount of 0 to 1.0% by mass 2 O. K in an amount of 0 to 0.5% by weight 2 O. Li in an amount of 0.4 to 1.0% by weight 2 O, and TiO in an amount of 0.2 to 1.5% by weight 2 A glass composition comprising: 2 O 3 ) / (SiO 2 + CaO) is at least 0.47, and the mass percent ratio (R3) (MgO / SiO 2 ) is at least 0.19 and has a fiberization temperature of 1,300°C or less.

2. 57.1% by mass to less than 59% by mass of SiO 2 The glass composition of claim 1 , comprising:

3. 2. The glass composition of claim 1, comprising 7.9% to less than 9.0% by weight of CaO.

4. SiO 2 , Al 2 O 3 2. The glass composition according to claim 1, wherein the total amount of MgO and CaO is at least 98% by weight and less than 99.5% by weight.

5. The glass composition of claim 1 , which is free of rare earth oxides.

6. More than 20% by mass to 21% by mass of Al 2 O 3 The glass composition of claim 1 , comprising:

7. 0.45% by mass to 0.8% by mass of Li 2 The glass composition of claim 1 , further comprising O.

8. B 2 O 3 The glass composition according to any one of claims 1 to 6, which is essentially free of:

9. 0.1 to 0.8 mass% Na 2 The glass composition of claim 1 , further comprising O.

10. A mass percent ratio (R2) (MgO + Al) greater than 0.46 2 O 3 +Li 2 O) / (CaO+SiO 2 +Na 2 O+K 2 10. The glass composition of claim 1, comprising:

11. SiO in an amount of more than 58.0 to 62.0% by mass 2 , Al in an amount of 20.0 to 25.0% by weight 2 O 3 , CaO in an amount of 7.9 to 12.0% by weight, MgO in an amount of 8.0 to 12.5% ​​by weight, Na in an amount of 0 to 1.0% by mass 2 O. K in an amount of 0 to 0.5% by weight 2 O. Li in an amount of 0.4 to 1.0% by weight 2 O, and TiO in an amount of 0.2 to 1.5% by weight 2 A glass composition comprising: 2 O 3 +Li 2 O) / (CaO+SiO 2 +Na 2 O+K 2 O) is greater than 0.46, and the mass percent ratio (R3) (MgO / SiO 2 ) is at least 0.19 and has a fiberization temperature of 1,300°C or less.

12. 57.1% by mass to less than 59% by mass of SiO 2 The glass composition of claim 11 , comprising:

13. 12. The glass composition according to claim 11, comprising 7.9 to less than 9.0 wt. % CaO.

14. SiO 2 , Al 2 O 3 12. The glass composition according to claim 11, wherein the total amount of MgO and CaO is at least 98% by weight and less than 99.5% by weight.

15. 12. The glass composition of claim 11, which is free of rare earth oxides.

16. More than 20% by mass to 21% by mass of Al 2 O 3 The glass composition of claim 11 , comprising:

17. 0.45% by mass to 0.8% by mass of Li 2 The glass composition according to claim 11, comprising O.

18. 0.1 to 0.8 mass% Na 2 The glass composition of claim 1 , further comprising O.

19. A mass percent ratio (R1) (MgO+Al) of at least 0.47 2 O 3 ) / (SiO 2 + CaO).

20. SiO in an amount of 57.0 to 62.0% by weight 2 , Al in an amount of 20.0 to 25.0% by weight 2 O 3 , CaO in an amount of 7.0 to 9.0% by weight, MgO in an amount of 8.0 to 12.5% ​​by weight, Na in an amount of 0 to 1.0% by mass 2 O. K in an amount of 0 to 0.5% by weight 2 O. Li in an amount of 0.4 to 1.0% by weight 2 O, and TiO in an amount of 0.2 to 1.5% by weight 2 Glass fibers formed from a glass composition comprising a mass percent ratio (R1) (MgO + Al 2 O 3 ) / (SiO 2 + CaO) is at least 0.47, and the mass percent ratio (R3) (MgO / SiO 2 ) is at least 0.19, and the glass composition has a fiberization temperature of 1,300°C or less and an elastic modulus of between 90 GPa and 92 GPa.

21. At least 2.6 g / cm 3 21. The glass fiber of claim 20 having a density:

22. The composition comprises from 57.1% to less than 59% by weight of SiO 2 21. The glass fiber of claim 20, comprising:

23. 21. The glass fiber of claim 20, wherein the composition comprises 7.9% to less than 9.0% by weight of CaO.

24. SiO 2 , Al 2 O 3 21. The glass fiber of claim 20, wherein the total amount of MgO and CaO is at least 98% by weight and less than 99.5% by weight.

25. Providing a molten composition according to claim 1; and drawing the molten composition through an orifice to form a continuous glass fiber.

1. A method for forming continuous glass fibers comprising:

26. a polymer matrix, and SiO in an amount of 57.0 to 62.0% by weight 2 , Al in an amount of 20.0 to 25.0% by weight 2 O 3 , CaO in an amount of 7.0 to 9.0% by weight, MgO in an amount of 8.0 to 12.5% ​​by weight, Na in an amount of 0 to 1.0% by mass 2 O. K in an amount of 0 to 0.5% by weight 2 O. Li in an amount of 0.4 to 1.0% by weight 2 O, and TiO in an amount of 0.2 to 1.5% by weight 2 a plurality of glass fibers formed from a glass composition comprising a mass percent ratio (R1) (MgO+Al 2 O 3 ) / (SiO 2 + CaO) is at least 0.47, and the mass percent ratio (R3) (MgO / SiO 2 ) is at least 0.19, the glass composition has a fiberization temperature of 1,300°C or less, and the glass fibers have an elastic modulus between 90 GPa and 92 GPa. Reinforced composite products, including:

27. 27. The reinforced composite product of claim 26 in the form of a wind blade.

Images