EA046930B1 - HIGH-QUALITY FIBERGLASS COMPOSITION WITH IMPROVED SPECIFIC MODULE OF ELASTICITY - Google Patents

Description

Description

Related applications

This application claims benefit to U.S. Provisional Patent Application Serial No. 62/771,245, filed November 26, 2018, entitled High Performance Fiberglass Composition with Improved Specific Modulus, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Glass fibers are made from various raw materials, combined in specific proportions to obtain the desired composition, usually called glass batch. This glass charge can be melted in a melting apparatus, and the molten glass is drawn into filaments through dies or a spinneret plate (the resulting filaments are also called continuous glass fibers). A sizing composition containing lubricants, binders and film-forming binder resins can then be applied to the threads. After application of the adhesive, the fibers can be collected into one or more strands and wound into packaging, or alternatively, the fibers can be chopped while wet and collected. 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.

The composition of the glass batch, together with the glass fibers made from it, is often expressed in terms of the oxides contained in it, which usually includes SiO ₂ , Al ₂ O ₃ , CaO, MgO, B ₂ O ₃ , Na ₂ O, K ₂ O , Fe ₂ O ₃ , TiO ₂ , Li ₂ O and the like. Many types of glass can be made from varying amounts of these oxides or by eliminating certain oxides from the glass batch. Examples of such glasses that can be produced include R glass, E glass, S glass, A glass, C glass and ECR glass. Glass composition controls the formation and properties of product glass. Other glass composition characteristics include raw material costs and environmental impact.

For example, E-glass is aluminoborosilicate glass, usually alkali-free, and is commonly used in electrical applications. One advantage of E-glass is that its liquidus temperature provides operating temperatures for glass fiber production of about 1900°F to 2400°F (1038°C to 1316°C). The ASTM classification for E-glass filaments used in printed circuit boards and aerospace applications specifies the composition as 52-56 wt% SiO ₂ , 16-25 wt% CaO, 12-16 wt% Al ₂ O ₃ , 5-10 wt.% B ₂ O ₃ , 0-5 wt.% MgO, 0-2 wt.% Na ₂ O and K2O, 0-0.8 wt.% TiO ₂ , 0.05-0, 4 wt.% Fe ₂ O ₃ and 0-1.0 wt.% fluorine.

Boron-free fibers are sold under the trade name ADVANTEX® (Owens Corning, Toledo, Ohio, USA). Boron-free fibers, such as those disclosed in US Pat. No. 5,789,329, incorporated herein by reference in its entirety, offer significant improvements in operating temperatures relative to boron-containing E-glass. Boron-free glass fibers fall within the ASTM definition of E-glass fibers for use in residential applications.

R-glass is a family of glasses that consist primarily of oxides of silicon, aluminum, magnesium and calcium with a chemical composition that produces glass fibers with greater mechanical strength than E-glass fibers. R-glass has a composition that contains from about 58 to about 60 wt.% SiO ₂ , from about 23.5 to about 25.5 wt.% Al ₂ O ₃ , from about 14 to about 17 wt.% CaO plus MgO and less than about 2 wt.% other components. R-glass contains more aluminum oxide and silica than E-glass and requires higher melting and processing temperatures to form fibers. Typically, the melting and processing temperatures for R-glass are higher than for E-glass. This increase in processing temperature requires the use of an expensive platinum-lined melting device. In addition, the close proximity of the liquidus temperature to the molding temperature of R-glass requires that the glass fiberize at a viscosity lower than that of E-glass, which typically fibers at about 1000 poise or so. R-glass fiber formation at a typical viscosity of 1000 poise will likely result in devitrification of the glass, causing process interruption and reduced productivity.

High quality glass fibers have greater strength and stiffness than traditional E-glass fibers. In particular, for some products, stiffness is important for modeling and performance. For example, composites such as wind turbine blades made from glass fibers with good stiffness properties will provide longer wind turbine blades in wind farms while keeping blade deflection within acceptable limits.

Additionally, high quality glass compositions are desired that have favorable mechanical and physical properties (eg, specific modulus and tensile strength) while maintaining desired formability (eg, liquidus temperature and fluff temperature). The modulus of elasticity is a measure of the stiffness of the fiber, defining the relationship between the load applied to the material and the deformation created by the material itself.

- 1 046930 material. A rigid material has a high modulus of elasticity and changes its shape only slightly under elastic loads. The flexible material has a low modulus of elasticity and changes its shape significantly. The specific modulus of elasticity is a measure of the modulus of elasticity per mass density of the fiberglass material. It may also be known as the stiffness-to-mass ratio and is often used to define glass fibers with minimal mass while not compromising stiffness.

Summary of the present invention

Various exemplary embodiments of the teachings of the present invention are directed to a glass composition containing: SiO2 in an amount of from 58.0 to 68.0 wt.%; Al2O ₃ in an amount from 18.0 to 23.0 wt.%; CaO in an amount from 1.0 to 9.0 wt.%; MgO in an amount from 9.0 to 14.0 wt.%; Na ₂ O in an amount from 0.0 to <1.0 wt.%; K2O in an amount from 0.0 to 1.0 wt.%; Li ₂ O in an amount from 0.0 to 4.0 wt.%; TiO ₂ in an amount from 0.0 to 4.0 wt.%; Y ₂ O ₃ in an amount from 0 to 10.0 wt.%; La ₂ O ₃ in an amount from 0 to 10.0 wt.%; Ce ₂ O ₃ in an amount from 0 to 2.5 wt.% and SC2O3 in an amount from 0 to 4.0 wt.%.

In some exemplary embodiments, the glass composition has a MgO/(CaO+SrO) ratio greater than 2.1.

In some exemplary embodiments, the glass fiber formed from the glass composition has a specific modulus of 34 to 40 MJ/kg.

The glass composition may additionally contain from 0 to 5.0 wt.% Ta ₂ O ₅ ; from 0 to 7.0 wt.% Ga ₂ O ₃ ; from 0 to 5.0 wt.% Nb ₂ O ₅ and from 0 to 5.0 wt.% V ₂ O ₅ .

In various exemplary embodiments, the glass composition is substantially free of B ₂ O ₃ .

In various exemplary embodiments, the glass composition contains from 0.1 to 3.5 wt.% Li ₂ O.

In various exemplary embodiments, the composition contains at least 1% by weight of the total amount of one or more of Y ₂ O ₃ , La ₂ O ₃ , Ce ₂ O ₃ , and Sc ₂ O ₃ .

In various exemplary embodiments, the composition contains less than 0.05 wt.% Sm ₂ O ₃ +Gd ₂ O ₃ .

Additional exemplary aspects of the teachings of the present invention are directed to glass fiber formed from a composition containing: SiO ₂ in an amount of from 55.0 to 68.0 wt.%; Al ₂ O ₃ in an amount from 18.0 to 23.0 wt.%; CaO in an amount from 1.0 to 9.0 wt.%; MgO in an amount from 9.0 to 14.0 wt.%; Na ₂ O in an amount from 0.0 to 1.0 wt.%; K2O in an amount from 0.0 to 1.0 wt.%; Li ₂ O in an amount of more than 1.0 to 4.0 wt.%; TiO ₂ in an amount from 0.0 to 4.0 wt.%; Y2O3 in an amount from 0 to 10.0 wt.%; La ₂ O ₃ in an amount from 0 to 10.0 wt.%; Ce ₂ O ₃ in an amount from 0 to 2.5 wt.% and Sc ₂ O ₃ in an amount from 0 to 4.0 wt.%. Glass fiber has a specific elastic modulus of 34 to 40 MJ/kg. Fiberglass also has a tensile strength per ASTM D2343-09 of at least 4400 MPa.

In various exemplary embodiments, the composition contains from 1.5 to 3.5 wt.% Li ₂ O.

In various typical embodiments, the composition contains from 1.0 to 5.0 wt.% CaO.

In various exemplary embodiments, the composition contains at least 1 wt.% the total amount of one or more of Y2O3, La2O3, Ce2O3 and Sc2O3.

Additional exemplary embodiments are directed to glass fibers that have a specific modulus of 35 to 36.5 MJ/kg.

Still other exemplary aspects of the teachings of the present invention are directed to a method of forming a continuous glass fiber comprising providing a molten glass composition and drawing the molten composition through an opening to form a continuous glass fiber.

Still other exemplary aspects of the teachings of the present invention are directed to a reinforced composite product comprising a polymer matrix and a plurality of glass fibers formed from a glass composition containing SiO ₂ in an amount of from 58.0 to 68.0 wt.%; Al ₂ O ₃ in an amount from 18.0 to 23.0 wt.%; CaO in an amount from 1.0 to 9.0 wt.%; MgO in an amount from 9.0 to 14.0 wt.%; Na ₂ O in an amount from 0.0 to 1.0 wt.%; K2O in an amount from 0.0 to 1.0 wt.%; Li ₂ O in an amount from 0.0 to 4.0 wt.%; TiO ₂ in an amount from 0.0 to 4.0 wt.%; Y ₂ O ₃ in an amount from 0 to 10.0 wt.%; La ₂ O ₃ in an amount from 0 to 10.0 wt.%; Ce ₂ O ₃ in an amount from 0 to 2.5 wt.% and SC2O3 in an amount from 0 to 4.0 wt.%.

In various exemplary embodiments, the glass composition has a MgO/(CaO+SrO) ratio greater than 2.1.

Glass fiber has a specific elastic modulus of 34 to 40 MJ/kg.

In some exemplary embodiments, the reinforced composite product is in the form of a wind turbine blade.

The above and other objects, features and advantages of the present invention will be more fully disclosed below herein by reference to the detailed description that follows.

Detailed Description of the Present Invention

Unless otherwise indicated, all technical and scientific expressions used herein have the same meaning as commonly understood by one skilled in the art to which these exemplary embodiments relate. The terminology used in the description of this document is intended to describe exemplary embodiments only and is not intended to limit exemplary embodiments. Therefore, the basic ideas of the invention are not

- 2 046930 are limited to the specific embodiments shown herein. Although other methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention, the preferred methods and materials are described herein.

When used in the specification and appended claims, the singular forms are intended to include also the plural forms unless the context clearly indicates otherwise.

Unless otherwise indicated, all numerical values expressing quantities of ingredients, chemical and molecular properties, reaction conditions, etc., used in the description and claims are to be understood as modified in all cases by the term about. Therefore, unless otherwise indicated, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending on the desired properties sought to be achieved by exemplary embodiments of the present invention. At a minimum, each numerical parameter should be considered in light of the number of significant figures and conventional rounding approaches.

Although the numerical ranges and parameters describing the broad meaning of typical embodiments are approximations, the numerical values shown in the specific examples are described as accurately as possible. Any numerical value, however, by definition contains some errors, which are inherently derived from the standard deviation provided by their respective test measurements. Each numerical range set forth in this specification and claims will include each narrower numerical range that falls within such broader numerical range as if such narrower numerical ranges were all expressly described herein. In addition, any numerical value set forth in the examples can be used to define either the upper or lower end point of the broader compositional range disclosed herein.

The present disclosure relates to a high quality glass composition with improved specific modulus. Such glass compositions are particularly interesting in the field of wind energy products, such as wind turbines, which require longer blades to generate more power. Longer blades require materials with a higher specific modulus of elasticity to withstand the forces applied to them without breaking or adding too much additional mass. The glass compositions of the present invention contain lithium and optionally oxides of rare earth elements. In addition, the glass compositions of the present invention contain higher levels of magnesium and alumina than other glass compositions in the art.

The glass compositions disclosed in the present invention are suitable for melting in conventional commercially available refractory-lined glass melting furnaces, which are widely used in the manufacture of glass fiber reinforcements.

The glass composition may be in molten form, obtained by melting the components of the glass composition in a melting device. The glass composition is characterized by a low fiberization temperature, which is defined as a temperature that corresponds to a melt viscosity of about 1000 poise, as determined according to ASTM C965-96 (2007). Reducing the fiberization temperature can reduce the cost of glass fibers because it provides longer die life and reduced energy consumption required to melt the components of the glass composition. Thus, the energy released is typically less than the energy required to melt many commercially available glass compositions.

These lower energy requirements may also reduce the overall manufacturing cost associated with glass composition.

For example, at a lower fiberization temperature, the spinneret can operate at the temperature of the cooling device and thus does not sag as quickly as is typically observed. Sagging is a phenomenon that occurs when a die that is maintained at elevated temperature for long periods of time loses its certain stability. Thus, by lowering the fiberization temperature, the sagging rate of the die can be reduced and the life of the die can be maximized.

In some exemplary embodiments, the glass composition has a fiberization temperature of less than 2650°F (1454.4°C), including fiberization temperatures of no more than 2600°F (1426.7°C), no more than 2550°F (1398.9°C) , not more than 2500°F (1371.1°C), not more than 2470°F (1354.4°C), not more than 2420°F (1326.7°C), not more than 2410°F (1321.1° C), not more than 2405°F (1318.3°C), not more than 2400°F (1315.6°C), not more than 2390°F (1310°C) and not more than 2385°F (1307.2°C) WITH). In some exemplary embodiments, the glass composition has a fiberization temperature of no more than 2300°F (1260°C), such as no more than 2500°F (1371.1°C) and no more than 2200°F (1204.4°C).

Another fiber-forming property of glass composition is the liquidus temperature. Liquidus temperature is defined as the highest temperature at which equilibrium exists between

- 3 046930 liquid glass and its primary crystalline phase. In some cases, the liquidus temperature can be measured by subjecting the glass composition to a temperature gradient in a platinum alloy trough for 16 hours (ASTM C829-81(2005)). At all temperatures above the liquidus temperature, the glass is completely molten, i.e. it does not contain crystals. At temperatures below the liquidus temperature, crystals can form.

In some exemplary embodiments, the glass composition has a liquidus temperature of less than 2600°F (1426.7°C), including a liquidus temperature of no more than 2400°F (1315.6°C), no more than 2375°F (1301.7°C) , not more than 2350°F (1287.8°C), not more than 2325°F (1273.9°C), not more than 2305°F (1262.8°C), not more than 2300°F (1260°C) , not more than 2290°F (1254.4°C), not more than 2250°F (1232.2°C), not more than 2225°F (1218.3°C) and not more than 2215°F (1212.8° WITH). In some exemplary embodiments, the glass composition has a liquidus temperature of from 2050°F (1121.1°C) to 2550°F (1398.9°C), including from 2150°F (1176.7°C) to 2490°F ( 1365.6°C), 2190°F (1198.9°C) to 2450°F (1343.3°C) and 2250°F (1232.2°C) to 2450°F (1343.3°C) WITH).

The third fiberizing property is AT, which is defined as the difference between the fiberization temperature and the liquidus temperature. If AT is too small, the molten glass may crystallize in the fiberizing device and cause disruption in the manufacturing process. It is desirable for AT to be as high as possible for a given formation viscosity as it offers a greater degree of flexibility in fiberization and helps avoid devitrification in both the glass distribution system and the fiberization apparatus. Large AT further reduces the cost of glass fiber production by providing longer die life and a less sensitive spinning process.

In some exemplary embodiments, the glass composition has an AT of at least -60°F (-33.3°C), including at least -20°F (-11.1°C), including at least 40°F ( 22.2°C), including at least 80°F (44.4°C), including at least 100°F (55.6°C), at least 110°F (61.1°C), by at least 120°F (66.7°C), at least 135°F (75°C), at least 150°F (55.6°C) and at least 170°F (94.4°C) . In various exemplary embodiments, the glass composition has an AT from 100°F (55.6°C) to 250°F (138.9°C), including from 120°F (66.7°C) to 200°F (111 .1°C) and 150°F (83.3°C) to 215°F (119.4°C).

The glass composition may contain from about 55.0 to about 68.0 wt.% SiO ₂ , from about 18.0 to about 23.0 wt.% Al ₂ O ₃ , from about 9.0 to about 14.0 wt. % MgO, 0 to about 9.0 wt.% CaO, 0.0 to about 1.0 wt.% Na ₂ O, 0 to about 1.0 wt.% K2O, 0 to about 4.0 wt.% TiO ₂ , from 0 to about 0.8 wt.% Fe ₂ O ₃ and from about 0.0 to about 4.0 wt.% Li ₂ O. The glass composition may also contain from 0 to about 10.0 wt.% Y ₂ O ₃ , from 0 to about 10.0 wt.% La ₂ O ₃ , from 0 to about 2.5 wt.% Ce ₂ O ₃ and from 0 to about 4.0 wt.% SC _{2 O3} . The glass composition may also contain from 0 to about 5.0 wt.% Ta ₂ O ₅ , from 0 to about 7.0 wt.% Ga ₂ O ₃ , from 0 to about 5.0 wt.% Nb ₂ O ₅ and from 0 to about 5.0 wt.% V ₂ O ₅ .

In some exemplary embodiments, the glass composition may contain from about 59.0 to about 65.0 wt.% SiO ₂ , from about 18.3 to about 22.0 wt.% Al ₂ O ₃ , from about 9.3 to about 12.0 wt% MgO, about 1.0 to about 8.5 wt% CaO, about 0.01 to about 0.5 wt% Na ₂ O, about 0.01 to about 0.5 wt.% K2O, from about 0.01 to about 3.5 wt.% TiO ₂ , from about 0.01 to about 0.6 wt.% Fe ₂ O ₃ and from about 0.1 to about 3.5 wt.% .% Li ₂ O. In some embodiments, the glass composition does not contain ZrO ₂ . The glass composition may also contain from about 0.01 to about 7.0 wt.% Y ₂ O ₃ , from about 0.01 to about 4.0 wt.% La ₂ O ₃ , from about 0.01 to about 2, 0 wt.% Ce ₂ O ₃ and from about 0.01 to about 3.5 wt.% SC ₂ O ₃ . The glass composition may also contain from about 0.01 to about 4.0 wt.% Ta ₂ O ₅ , from about 0.01 to about 6.0 wt.% Ga ₂ O ₃ , from about 0.01 to about 4. 0 wt.% Nb ₂ O ₅ and from about 0.01 to 4.0 wt.% V ₂ O ₅ .

The glass composition contains at least 50 wt.% and no more than about 75 wt.% SiO ₂ . In some exemplary embodiments, the glass composition contains at least about 55 wt.% SiO ₂ , including at least 57 wt.%, at least 58 wt.%, at least 58.5 wt.% and at least 59 wt.%. In some exemplary embodiments, the glass composition contains no more than about 70 wt.% SiO2, including no more than 68 wt.%, no more than 65.5 wt.%, no more than 63 wt.%, no more than 61 wt.%, and no more more than 60.5 wt.%. In some exemplary embodiments, the glass composition contains from about 59 wt.% to about 68 wt.% or from about 60 wt.% to about 65 wt.% SiO ₂ .

To achieve both the desired mechanical and fiberizing properties, one important aspect of the glass composition is to have an Al ₂ O ₃ concentration of at least about 16.0 wt.% and no more than 25 wt.%. The inclusion of more than about 25 wt.% Al ₂ O ₃ causes the liquidus of the glass to increase to a level above the fiberization temperature, which gives a negative ΔΤ. Inclusion of less than 17 wt.% Al2O3 produces a glass fiber with an undesirably low modulus. In some exemplary embodiments, the glass composition contains at least about 17.0 wt.% Al ₂ O ₃ , including at least 18.0 wt.%, at least 19.0 wt.%, at least 19.5 wt.% and at least 20.0 wt.%. In some exemplary embodiments, the glass composition contains from about 18.3 to about 23 wt.% Al ₂ O ₃ , including from about 18.8 to about 22 wt.% Al ₂ O ₃ .

The glass composition preferably also contains at least about 8.0 wt.% and no more than about 15 wt.% MgO. Inclusion of more than about 15 wt.% MgO will cause an increase in temperature

- 4 046930 liquidus, which also increases the tendency for glass to crystallize. Inclusion of less than about 8.0 wt.% produces a glass fiber with an undesirably low modulus if substituted with CaO, and an undesirable increase in viscosity if substituted with SiO2. In some exemplary embodiments, the glass composition contains at least about 9.0 wt.% MgO, including at least 9.2 wt.%, at least 9.5 wt.%, at least 10 wt.%, at least 11 wt%, at least 11.25 wt%, at least 12.5 wt% and at least 13 wt% MgO. In some exemplary embodiments, the glass composition contains a MgO concentration of from about 9.3 to about 14 weight percent, or from about 9.6 to about 12 weight percent.

The glass composition may optionally contain CaO in concentrations up to about 10.0 wt.%. Inclusion of more than about 10 wt.% CaO produces a glass with a lower than desirable elastic modulus. In some exemplary embodiments, the glass composition contains from 0 to about 9 wt.% CaO, including from 0.5 to 8.8 wt.%, from 1.0 to 8.5 wt.%, from 1.5 to 8. 0 wt.% and from 2.0 to 5.5 wt.%. In some exemplary embodiments, the glass composition contains a CaO concentration of from 1.0 wt.% to 5.5 wt.%.

In some exemplary embodiments, the combined concentration of MgO and CaO is at least about 10 wt% and no more than about 22 wt%, including from 12.0 wt% to 20 wt% and from 14 wt% to 19.5 wt%. wt.%.

The glass composition may contain up to about 5.0 wt.% TiO ₂ . In some exemplary embodiments, the glass composition contains from 0 wt.% to about 4.0 wt.% TiO ₂ , including from about 0.01 wt.% to about 3.5 wt.% and from about 0.1 to about 0 .75 wt.%.

The glass composition may contain up to about 1.0 wt.% Fe ₂ O ₃ . In some exemplary embodiments, the glass composition contains from 0 wt.% to about 0.8 wt.% Fe ₂ O ₃ , including from about 0.01 wt.% to about 0.6 wt.% and from about 0.1 to about 0.35 wt.%.

The glass composition may contain up to about 5.0 wt.% Li ₂ O. In some exemplary embodiments, the glass composition contains from about 0.0 wt.% to about 4.0 wt.% Li ₂ O, including from about 0.1 wt.% to about 3.5 wt.% and from about 0.5 to about 3.0 wt.%. In some exemplary embodiments, the glass composition contains from about 1.0 to about 4.0 weight percent Li ₂ O or from about 1.5 to about 3.8 weight percent Li ₂ O.

In some exemplary embodiments, the glass composition contains less than about 2.0 wt.% alkali metal oxides Na ₂ O and K2O, including from 0 to about 1.5 wt.%, from 0.05 to 0.75 wt.% and from 0.1 to 0.3 wt.%. The glass composition may contain both Na ₂ O and K2O in an amount greater than about 0.01 wt.% of each oxide. In some exemplary embodiments, the glass composition contains from about 0 to about 1 wt.% Na ₂ O, including from about 0.01 to about 0.5 wt.%, from about 0.03 to about 0.3 wt.% and from 0.04 to about 0.15 wt.%. In some exemplary embodiments, the glass composition contains from about 0 to about 1 wt% K2O, including from about 0.01 to about 0.5 wt%, from about 0.03 to about 0.3 wt%, and from 0 .04 to about 0.15 wt.%. In some exemplary embodiments, the glass composition contains less than 1.0 wt% K2O, such as less than 0.75 wt% or less than 0.50 wt%.

The glass composition may contain up to about 1.5 wt.% ZrO ₂ . In some exemplary embodiments, the glass composition contains from about 0.01 wt.% to about 1.0 wt.% ZrO ₂ , including from about 0.05 wt.% to about 0.8 wt.% and from about 0.1 up to about 0.5 wt.%.

In some exemplary embodiments, the glass composition contains up to about 10.0 wt.% rare earth oxides Y ₂ O ₃ , La ₂ O ₃ , Ce ₂ O ₃ and SC ₂ O ₃ (R ₂ O ₃ ), including 0 to 10 .0 wt.% or from 0.1 to 7.0 wt.%. The glass composition may contain any of the oxides R ₂ O ₃ in an amount greater than about 0.01 wt.%. In some exemplary embodiments, the glass composition contains from about 0 to about 10 wt.% Y ₂ O ₃ , including from about 0.01 to about 7.0 wt.%, from about 0.05 to about 4.0 wt.% and from 0.8 to about 3.5 wt.%. In some exemplary embodiments, the glass composition contains from about 0 to about 10 wt.% La ₂ O ₃ , including from about 0.01 to about 4.0 wt.%, from about 0.05 to about 3.5 wt.% and from 0.1 to about 3.0 wt.%. In some exemplary embodiments, the glass composition contains from about 0 to about 2.5 wt.% Ce ₂ O ₃ , including from about 0.01 to about 2.0 wt.%, from about 0.05 to about 1.8 wt. .% and from 0.1 to about 1.5 wt.%. In some exemplary embodiments, the glass composition contains from about 0 to about 4 wt.% SC ₂ O ₃ , including from about 0.01 to about 3.5 wt.%, from about 0.05 to about 3.2 wt.% and from 0.1 to about 3.0 wt.%.

In some exemplary embodiments, the glass composition contains a total concentration of CeO ₂ +SC ₂ O ₃ that is at least 1.0 wt.%, including at least 1.5 wt.%, at least 1.75 wt.% , at least 2.0 wt.%, at least 2.1 wt.%, at least 2.2 wt.% and at least 2.5 wt.%.

The glass composition may contain up to about 5.0 wt.% Ta2O5. In some exemplary embodiments, the glass composition contains from about 0.01 wt% to about 4.0 wt% Ta2O5, including from about 0.05 wt% to about 3.5 wt% and from about 0.1 to about 3.0 wt.%.

The glass composition may contain up to about 7.0 wt.% Ga ₂ O ₃ . In some exemplary embodiments, the glass composition contains from about 0.01 wt.% to about 6.0 wt.% Ga ₂ O ₃ , including from about 0.05 wt.% to about 5.5 wt.% and from about 0 .1 to about 5.0 wt.%.

The glass composition may contain up to about 5.0 wt.% Nb ₂ O ₅ . In some typical variants

- 5 046930 glass composition contains from about 0.01 wt.% to about 4.0 wt.% Nb2O5, including from about 0.05 wt.% to about 3.5 wt.% and from about 0.1 to about 3.0 wt.%.

The glass composition may contain up to about 5.0 wt.% V2O5. In some exemplary embodiments, the glass composition contains from about 0.01 wt.% to about 4.0 wt.% V2O5, including from about 0.05 wt.% to about 3.5 wt.% and from about 0.1 to about 3.0 wt.%.

Glass compositions may contain up to about 1.0 wt.% Sm2O ₃ and/or Gd2O ₃ . However, various exemplary embodiments limit the total concentration of Sm ₂ O ₃ and Gd ₂ O ₃ to less than 0.5 wt.%, including less than 0.1 wt.% and less than 0.05 wt.%.

The glass composition may contain up to about 5.0 wt.% ZnO. In some exemplary embodiments, the glass composition contains from 0 wt.% to about 2.5 wt.% ZnO, including from about 0.01 wt.% to about 2.0 wt.% and from about 0.1 to about 1. 0 wt.%.

The glass compositions of the present invention may contain no or substantially no B ₂ O ₃ and fluorine, although either may be added in small amounts to control the fiberizing properties and final properties of the glass and will not adversely affect the properties if maintained below several percent. As used herein, it is substantially free of B ₂ O ₃ and fluorine, meaning that the sum of the amounts of B ₂ O ₃ and fluorine present is less than 1.0% by weight of the composition. The sum of the amounts of B ₂ O ₃ 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. .%.

Glass formulations may also contain impurities and/or trace materials without adversely affecting the glasses or fibers. These impurities may enter the glass as raw material impurities or may be products obtained from the chemical reaction of the molten glass with the furnace components. Non-limiting examples of trace materials include strontium, barium, and combinations thereof. Trace materials may be present in their oxide forms and may also include fluorine and/or chlorine. In some exemplary embodiments, the glass compositions of the present invention contain no more than about 1.0 wt%, including less than 0.5 wt%, less than 0.2 wt%, and less than 0.1 wt%, each of BaO, SrO, P ₂ O ₅ and SO ₃ . In particular, the glass composition may contain less than about 5.0 wt.% in total BaO, SrO, P ₂ O ₅ and/or SO ₃ , each of BaO, SrO, P ₂ O ₅ and SO ₃ , if present at all, is present in an amount of less than 1.0 wt.%.

In some exemplary embodiments, the glass composition contains a MgO/(CaO+SrO) ratio that is at least 1.5, including at least 1.7, at least 2.0, at least 2.1, at least at least 2.2 and at least 2.3.

When used herein, the terms weight percent, weight %, wt.% and weight percent can be used interchangeably and are understood to mean weight percent (or weight percent) based on the total composition.

As stated above, the glass compositions of the present invention unexpectedly exhibit optimized specific modulus while maintaining desirable molding properties.

The tensile strength of the fiber is also referred to herein simply as strength. In some exemplary embodiments, tensile strength is measured on fresh fibers (ie, unglued and untouched laboratory-derived fibers) using an Instron tensile strength tester according to ASTM D2343-09. Typical glass fibers produced from the glass composition of the present invention described above may have a fiber tensile strength of at least about 3500 MPa, including at least 4000 MPa, at least 4000 MPa, at least 4400 MPa, at least 4500 MPa , at least 4800 MPa, at least 4900 MPa, at least 4950 MPa, at least 5000 MPa, at least 5150 MPa and at least 5200 MPa. In some exemplary embodiments, glass fibers produced from the composition described above have a fiber tensile strength of from about 3500 MPa to about 5500 MPa, including from about 4000 MPa to about 5350 MPa, from about 4600 MPa to about 5315 MPa. Preferably, the combination of compositional parameters disclosed herein makes it possible to obtain glass fibers having tensile strengths of at least about 4800 MPa, including at least 4900 MPa and at least 5000, which has not yet been achieved in the prior art with a glass composition. having the desired fiber-forming properties.

The modulus of elasticity of a glass fiber can be determined by taking the average measurements from five individual glass fibers measured according to the acoustic measurement procedure outlined in the report Glass Fiber Drawing and Measuring Facilities at the U.S. Naval Ordnance Laboratory, Report Number NOLTR 6587, June 23, 1965.

Typical glass fibers produced from the glass composition of the present invention may have an elastic modulus of at least about 85 GPa, including at least about 88 GPa, at least about 88.5 GPa, at least about 89 GPa, or at least about 89 .5 GPa. In some exemplary embodiments, typical glass fibers produced from the glass composition of the present invention have an elastic modulus of from about 85 GPa to about 115 GPa, including from about 87 GPa to

- 6 046930 about 100 GPa and from about 88 GPa to about 98 GPa.

The elastic modulus can then be used to determine the specific modulus. It is desirable to have the specific modulus as high as possible to provide a lightweight composite material that adds stiffness to the finished product. Specific modulus is important in applications where product stiffness is an important parameter, such as in wind power and aerospace applications. When used herein, the specific modulus is calculated according to the following equation:

Specific modulus (MJ/kg) = Modulus (GPa)/Density (kg/cubic meter).

Typical glass fibers produced from the glass composition of the present invention have a specific modulus of from about 33.0 MJ/kg to about 40.0 MJ/kg, including from about 34.5 MJ/kg to about 37 MJ/kg and from about 35. 8 MJ/kg to about 36.5 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)) on green glass. Glass fibers have a density of about 2.0 to about 3.0 g/cm ³ . In other exemplary embodiments, the glass fibers have a density of from about 2.3 to about 2.8 g/cm ³ , including from about 2.4 to about 2.78 g/cm ³ and from about 2.49 to about 2.75 g/cm 3 /cm ³ .

According to some exemplary embodiments, a method is provided for producing glass fibers from the glass composition described above. Glass fibers can be produced by any means known and conventionally used in the art. In some exemplary embodiments, glass fibers are formed by obtaining raw ingredients and mixing the ingredients in appropriate quantities to obtain the desired weight percentages in the finished composition. The method may also include providing the glass composition of the present invention in molten form and drawing the molten composition through holes in a die to produce glass fiber.

Glass composition components can be prepared from suitable ingredients or raw materials, including, but not limited to, sand or pyrophyllite for SiO ₂ , limestone, burnt lime, wollastonite or dolomite for CaO, kaolin, alumina or pyrophyllite for Al ₂ O ₃ ,. dolomite, quicklime, brucite, enstatite, talc, burnt magnesite or magnesite for MgO and sodium carbonate, albite or sodium sulfate for Na ₂ O. In some exemplary embodiments, cullet can be used to provide one or more of the required oxides.

The mixed batch can then be melted in a furnace or melting apparatus and the resulting molten glass passes along the prechamber and is drawn through the holes of a die located at the bottom of the prechamber to produce individual glass strands. In some exemplary embodiments, the furnace or melting device is a traditional refractory melting device. By using a refractory container made from refractory blocks, the manufacturing cost associated with producing glass fibers obtained from the composition of the present invention can be reduced. In some exemplary embodiments, the die is a platinum alloy die. Strands of glass fibers can then be formed by gathering individual strands together. The fiber strands can be wound and further processed in a conventional manner suitable for the intended application.

The operating temperatures of the glass in the melting apparatus, pre-chamber and die can be selected to suitably control the viscosity of the glass and can be maintained by suitable means such as control devices. The temperature at the front end of the melting device can be automatically controlled to reduce or eliminate devitrification. The molten glass can then be drawn (pulled) through holes or openings in the bottom or end plate of the die to produce glass fibers. In some exemplary embodiments, streams of molten glass flowing through the die openings are reduced to filaments by winding a strand formed from a plurality of individual filaments onto a forming tube mounted on a rotating sleeve of a winding machine, or chopping at a controlled speed. The glass fibers of the present invention are produced by any of the methods described herein or by any known method for forming glass fibers.

The fibers can be further processed in a conventional manner suitable for the intended application. For example, in some exemplary embodiments, glass fibers are sized with a sizing composition known to those skilled in the art. The sizing composition is not limited in any way and can be any sizing composition suitable for application to glass fibers. Bonded fibers can be used to reinforce substrates such as a variety of plastics if the end user of the product requires high strength and stiffness and low weight. Such applications include, but are not limited to, woven materials for use in forming wind turbine blades; internal structure such as reinforcing concrete, bridges, etc.; and aerospace engineering.

However, some typical embodiments of the present invention include a composite material containing glass fibers of the present invention, as described above, in combination

- 7 046930 with curing matrix material. It may also be referred to herein as a reinforced composite product. The matrix material may be any suitable thermoplastic or thermoset resin known to those skilled in the art, such as, but not limited to, thermoplastics such as polyesters, polypropylene, polyamide, polyethylene terephthalate and polybutylene, and thermoset resins such as epoxy resins, unsaturated polyesters , phenolic resins, vinyl esters and elastomers. These resins can be used individually or in combination. The reinforced composite product can be used for wind turbine blades, reinforcing bar, pipe, fiber winding, muffler filler, sound absorption and the like.

According to further exemplary embodiments, the present invention provides a method for producing a composite product as described above. The method may include combining at least one polymer matrix material with a plurality of glass fibers. Both the matrix polymer material and the glass fibers may be as described above.

Examples

Typical glass compositions according to the present invention were prepared by mixing the batch components in proportional amounts to obtain a finished glass composition with the oxide weight percentages shown in Tables 1-8 below.

The raw materials were melted in a platinum crucible in an electric furnace at a temperature of 1650°C for 3 hours.

The fiberization temperature was measured using the rotating cylinder method as described in ASTM C965-96 (2007), entitled Standard Practice for Measuring the Viscosity of Glass Above the Softening Point, the contents of which are incorporated by reference herein. The liquidus temperature was measured by exposing the glass to a temperature gradient in a platinum alloy trough for 16 hours, as defined in ASTM C829-81(2005), entitled Standard Practices for the Measurement of Liquidus Temperature of Glass, the contents of which are incorporated by reference herein. Density was measured according to the Archimedes method as detailed in ASTM C69393(2008), entitled Standard Test Method for Glass Density by Buoyancy, the contents of which are incorporated by reference herein.

The specific modulus was calculated by dividing the measured modulus in GPa units by the density in kg/m ³ units.

Strength was measured on fresh fiber using an Instron tensile strength tester per ASTM D2343-09 entitled Standard Test Method for Tensile Mechanical Properties of Fiberglass Strands, Yarns, and Rovings Used in Reinforced Plastics, the contents of which are incorporated by reference herein.

Table 1

Component Etc. 1 (wt.%) Etc. 2 (wt.%) Ave.3 (wt.%) Etc. 4 (wt.%) Etc. 5 (wt.%) Etc. 6 (wt.%) _SiO2 60.00 64.00 65.00 64.50 63.00 63.50 A1 ₂ 0з 22.00 21.00 21.00 20.50 21.00 20.50 MgO 14.0 12.00 12.00 12.00 12.00 12.00 Sao 0.00 1.00 0.00 1.00 2.00 2.00 _Li2O 4.00 2.00 2.00 2.00 2.00 2.00 _{Fe2O3 ​} 0.00 0.00 0.00 0.00 0.00 0.00 K ₂ O 0.00 0.00 0.00 0.00 0.00 0.00 _Na2O 0.00 0.00 0.00 0.00 0.00 0.00 _TiO2 0.00 0.00 0.0 0.00 0.00 0.00 Property Fiberization Temperature (°F) 2258 (1236.7 °C) 2481 (1360.6 °C) 2520 (1382.2 °C) 2510 (1376.7 °C) 2459 (1348.3 °C) 2456 (1346.7 °C) Liquidus temperature (°F) 2262 (1238.9 °C) 2267 (1241.7 °C) 2434 (1334.4 °C) 2381 (1305.0 °C) 2341 (1282.8 °C) 2330 (1276.7 °C) ΔΤ (°F) -4 (-2.2 °C) 115 (63.9 °C) 86 (47.8 °C) 123 (68.3 °C) 119 (66.1 °C) 126 (70.0 °C) Density (g/cm ³ ) 2,540 2,517 2,495 2,522 2,529 2,564

- 8 046930

Modulus of elasticity (GPa) 92.4 91.4 90.5 91.4 91.6 92.0 Specific modulus (MJ/kg) 36.40 36.30 36.3 36.3 36.2 36.1 Tensile strength (MPa) 4936 5132 4923 5315 5224 5186

table 2

Component Etc. 7 (wt.%) Etc. 8 (wt.%) Etc. 9 (wt.%) Etc. 10 (wt.%) Etc. 11 (wt.%) _SiO2 62.00 59.00 62.4 62.50 65.50 A1 ₂ 0з 21.00 22.0 20.30 20.50 20.50 MgO 12.00 12.00 12.00 12.00 12.00 Sao 3.00 3.00 3.30 3.00 0.00 _Li2O 2.00 2.00 2.00 2.00 2.00 _{Fe2O3 ​} 0.00 0.00 0.00 0.00 0.00 K ₂ O 0.00 0.00 0.00 0.00 0.00 _Na2O 0.00 0.00 0.00 0.00 0.00 _TiO2 0.00 2.00 0.00 0.00 0.00 Property Fiberization temperature (T) 2420 (1326.7 °C) 2321 (1271.7 °C) 2388 (1308.9 °C) 2398 (1314.4 °C) 2499 (1370.6 °C) Liquidus temperature (°F) 2310 (1265.6 °C) 2316 (1268.9 °C) 2268 (1242.2 °C) 2281 (1249.4 °C) 2407 (1319.4 °C) ΔΤ (°F) 111 (61.7 °C) 6 (3.3 °C) 121 (67.2 °C) 117 (65.0 °C) 93 (51.7 °C) Density (g/cm ³ ) 2.545 2,571 2,540 2,543 2,494 Modulus of elasticity (GPa) 91.9 92.8 91.6 91.6 89.7 Specific modulus (MJ/kg) 36.1 36.1 36.0 36.0 36.0 Tensile strength (MPa) 5234 5035 5026 5197 5018

Table 3

Component Etc. 12 (wt.%) Etc. 13 (wt.%) Etc. 14 (wt.%) Etc. 15 (wt.%) Etc. 16 (wt.%) _SiO2 59.95 60.00 61.20 60.50 61.00 A1 ₂ 0з 19.45 20.5 19.85 20.50 20.50 MgO 11.15 12.00 9.82 12.00 12.00 Sao 5.13 1.50 5.23 1.50 2.50 _Li2O 1.85 2.00 1.89 2.00 2.00

- 9 046930

_{Fe2O3 ​} 0.00 0.00 0.00 0.00 0.00 K ₂ O 0.00 0.00 0.00 0.00 0.00 _Na2O 0.00 0.00 0.00 0.00 0.00 _TiO2 0.00 0.00 0.00 0.00 0.00 _{Sc2O3 ​} 4.00 0.00 2.00 0.00 0.00 _{Y2O3 ​} 0.00 3.00 0.00 3.50 0.00 _ZrO2 0.00 1.00 0.00 0.00 0.00 _{Nb2O5 ​} 0.00 0.00 0.00 0.00 2.00 La ₂ O ₃ 0.00 0.00 0.00 0.00 0.00 _{Ga2O3 ​} 0.00 0.00 0.00 0.00 0.00 Property Fiberization Temperature (°F) 2350 (1287.8 °C) 2355 (1290.6 °C) 2381 (1305.0 °C) 2367 (1297.2 °C) 2356 (1291.1 °C) Liquidus temperature (°F) 2405 (1318.3 °C) 2310 (1265.6 °C) 2235 (1223.9 °C) 2308 (1264.4 °C) 2317 (1269.4 °C) ΔΤ (°F) 176 (97.8 °C) 45 (25.0 °C) 146 (81.1 °C) 59 (32.8 °C) 40 (22.2 °C) Density (g/cm ³ ) 2,602 2,600 2,577 2,593 2,558 Modulus of elasticity (GPa) 93.5 93.1 92.2 92.8 91.3 Specific modulus (MJ/kg) 35.9 35.8 35.8 35.8 35.7 Tensile strength (MPa) 4818 4984 5056 5058 .—

Table 4

Component Etc. 17 (wt.%) Etc. 18 (wt.%) Etc. 19 (wt.%) Etc. 20 (wt.%) Etc. 21 (wt.%) _SiO2 50.89 61.00 61.00 60.0 61.83 A1 ₂ O ₃ 22.92 20.5 20.5 20.0 20.06 MgO 12.46 12.0 12.00 12.00 9.92 Sao 4.47 2.50 2.50 2.00 5.29 S ₂ O 2.20 2.00 2.00 2.00 1.91 _{Fe2O3 ​} 0.01 0.00 0.00 0.00 0.00 K ₂ O 0.01 0.00 0.00 0.00 0.00

- 10 046930

_Na2O 0.03 0.00 0.00 0.00 0.00 _TiO2 0.01 0.00 0.00 0.00 0.00 _{Sc2O3 ​} 0.00 0.00 0.00 0.00 0.00 _{Y2O3 ​} 5.49 0.00 0.00 0.00 0.00 _ZrO2 0.00 0.00 0.00 1.00 1.00 _{Nb2O5 ​} 0.00 0.00 0.00 0.00 0.00 La ₂ O ₃ 1.50 0.00 0.00 0.00 0.00 _{Ga2O3 ​} 0.00 2.00 0.00 0.00 0.00 _{Ta2O5 ​} 0.00 0.00 2.00 0.00 0.00 _{V2O5 ​} 0.00 0.00 0.00 0.00 0.00 Property Fiberization Temperature (°F) 2193 (1200.6 °C) 2375 (1301.7 °C) 2380 (1304.4 °C) 2371 (1299.4 °C) 2443 (1339.4 °C) Liquidus temperature (°F) 2217 (1213.9 °C) 2299 (1259.4 °C) 2287 (1252.8 °C) 2321 (1271.7 °C) 2230 (1221.1 °C) ΔΤ (°F) -24 (-13.3 °C) 77 (42.8 °C) 94 (52.2 °C) 50 (27.8 °C) 213 (118.3 °C) Density (g/cm ³ ) 2,744 2,562 2,571 2,596 2,559 Modulus of elasticity (GPa) 98.0 91.3 91.6 92.3 92.3 Specific modulus (MJ/kg) 35.7 35.6 35.6 35.5 35.5 Tensile strength (MPa) — — — .— 5016

Table 5

Component Etc. 22 (wt.%) Etc. 23 (wt.%) Etc. 24 (wt.%) Etc. 25 (wt.%) Etc. 26 (wt.%) _SiO2 58.00 61.00 63.50 64.00 60.00 ai ₂ o ₃ 20.00 20.50 20.50 21.00 20.50 MgO 12.00 12.00 11.70 11.70 12.00 SaO 2.00 2.50 4.00 3.00 1.50 S ₂ O 2.00 2.00 0.00 0.00 2.00 _{Fe2O3 ​} 0.00 0.00 0.00 0.00 0.00 K ₂ O 0.00 0.00 0.00 0.00 0.00

- 11 046930

_Na2O 0.00 0.00 0.30 0.30 0.00 _TiO2 0.00 0.00 0.00 0.00 0.00 _{Sc2O3 ​} 0.00 0.00 0.00 0.00 0.00 _{Y2O3 ​} 4.00 0.00 0.00 0.00 0.00 _ZrO2 0.00 0.00 0.00 0.00 1.00 _{Nb2O5 ​} 0.00 0.00 0.00 0.00 0.00 La ₂ O ₃ 3.00 0.00 0.00 0.00 3.00 _{Ga2O3 ​} 0.00 2.00 0.00 0.00 0.00 _{Ta2O5 ​} 3.00 0.00 2.00 0.00 0.00 _{V2O5 ​} 0.00 2.00 0.00 0.00 0.00 Property Fiberization Temperature (°F) 2326 (1274.4 °C) 2360 (1293.3 °C) 2545 (1396.1 °C) 2573 (1411.7 °C) 2360 (1293.3 °C) Liquidus temperature (°F) 2248 (1231.1 °C) 2311 (1266.1 °C) 2454 (1345.6 °C) 2490 (1365.6 °C) 2289 (1253.9 °C) ΔΤ (°F) 79 (43.9 °C) 49 (27.2 °C) 92 (51.1 °C) 84 (46.7 °C) 71 (39.4 °C) Density (g/cm ³ ) 2.656 2,540 2,536 2,520 2,597 Modulus of elasticity (GPa) 94.3 90.2 89.7 89.1 91.8 Specific modulus (MJ/kg) 35.5 35.5 35.4 35.4 35.4 Tensile strength (MPa) 4919 — — .— 4953

Table 6

Component Etc. 27 (wt.%) Etc. 28 (wt.%) Etc. 29 (wt.%) Etc. 30 (wt.%) Etc. 31 (wt.%) _SiO2 61.00 61.00 58.00 60.50 61.00 ai ₂ o ₃ 20.00 20.00 20.00 20.50 20.00 MgO 11.50 11.50 12.00 12.00 11.50 Sao 2.00 2.00 2.00 1.50 2.00 S ₂ O 1.50 1.50 2.00 2.00 1.50 _{Fe2O3 ​} 0.00 0.00 0.00 0.00 0.00 K ₂ O 0.00 0.00 0.00 0.00 0.00

- 12 046930

_Na2O 0.00 0.00 0.00 0.00 0.00 _TiO2 0.00 0.00 0.00 0.00 0.00 _{Sc2O3 ​} 0.00 0.00 0.00 0.00 0.00 _{Y2O3 ​} 0.00 0.00 3.00 0.00 0.00 _ZrO2 0.00 0.00 0.00 0.00 0.00 _{Nb2O5 ​} 4.00 0.00 0.00 0.00 0.00 La ₂ O ₃ 3.00 0.00 0.00 0.00 0.00 _{Ga2O3 ​} 0.00 4.00 0.00 0.00 0.00 _{Ta2O5 ​} 3.00 0.00 3.00 0.00 4.00 _{V2O5 ​} 0.00 2.00 0.00 0.00 0.00 Property Fiberization Temperature (°F) 2404 (1317.8 °C) 2423 (1328.3 °C) 2319 (1270.6 °C) 2367 (1297.2 °C) 2380 (1304.4 °C) Liquidus temperature (°F) 2264 (1240.0 °C) 2376 (1302.2 °C) 2256 (1235.6 °C) 2310 (1265.6 °C) 2374 (1301.1 °C) ΔΤ (°F) 41 (22.8 °C) 48 (26.7 °C) 63 (35.0 °C) 57 (31.7 °C) 7 (3.9 °C) Density (g/cm ³ ) 2,570 2,577 2.651 2,597 2,593 Modulus of elasticity (GPa) 90.9 91.9 93.7 91.7 91.5 Specific modulus (MJ/kg) 35.4 35.3 35.3 35.3 35.3 Tensile strength (MPa) .— — 4929 4959 .—

Table 7

Component Etc. 32 (wt.%) Etc. 33 (wt.%) Etc. 34 (wt.%) Etc. 35 (wt.%) Etc. 36 (wt.%) _SiO2 60.26 57.33 61.20 61.20 58.00 ai ₂ o ₃ 19.55 19.61 19.85 19.85 20.00 MgO 9.67 10.94 9.82 9.82 eleven SaO 5.15 8.83 5.23 5.23 3.00 S ₂ O 1.87 2.00 1.89 1.89 2.00 _{Fe2O3 ​} 0.00 0.34 0.00 0.00 0.00 K ₂ O 0.00 0.13 0.00 0.00 0.00

- 13 046930

_Na2O 0.00 0.12 0.00 0.00 0.00 _TiO2 0.00 0.68 2.00 0.00 0.00 _CeO2 0.00 0.00 0.00 2.00 0.00 _{Sc2O2 ​} 0.00 0.00 0.00 0.00 0.00 _{Y2O3 ​} 3.50 0.00 0.00 0.00 3.00 _ZrO2 0.00 0.00 0.00 0.00 1.00 _{Nb2O5 ​} 0.00 0.00 0.00 0.00 0.00 La ₂ O ₃ 0.00 0.00 0.00 0.00 2.00 Oa ₂ Oz 0.00 0.00 0.00 0.00 0.00 _{Ta2O5 ​} 0.00 0.00 0.00 0.00 0.00 _{V2O5 ​} 0.00 0.00 0.00 0.00 0.00 Property Fiberization Temperature (°F) 2378 (1303.3 °C) 2236 (1224.4 °C) 2359 (1292.8 °C) 2391 (1310.6 °C) 2323 (1272.8 °C) Liquidus temperature (°F) 2191 (1199.4 °C) 2190 (1198.9 °C) 2330 (1276.7 °C) 2242 (1227.8 °C) 2222 (1216.7 °C) ΔΤ (°F) 188 (104.4 °C) 47 (26.1 °C) 30 (16.7 °C) 149 (82.8 °C) 101 (56.1 °C) Density (g/cm ³ ) 2,607 2,620 2.565 2,580 2,649 Modulus of elasticity (GPa) 92.0 92.4 90.4 90.6 93.0 Specific modulus (MJ/kg) 35.3 35.3 35.2 35.1 35.1 Tensile strength (MPa) 4927 — 4898 5021 .—

Table 8

Component Etc. 37 (wt.%) Etc. 38 (wt.%) Etc. 39 (wt.%) Etc. 40 (wt.%) Etc. 41 (wt.%) Comparative example _SiO2 59.95 61.00 55.50 58.08 59.50 60.70 A1 ₂ 0з 19.45 20.00 21 18.84 20.00 15.80 MgO 9.62 11.50 11.00 9.32 11.00 8.00 SaO 5.13 2.00 3.50 4.97 2.00 13.40 S ₂ O 1.85 1.50 2.00 1.79 1.50 0.75 _{Fe2O3 ​} 0.00 0.00 0.00 0.00 0.00 0.27

- 14 046930

K ₂ O 0.00 0.00 0.00 0.00 0.00 0.10 _Na2O 0.00 0.00 0.00 0.00 0.00 0.23 _TiO2 4.00 0.00 0.00 0.00 0.00 0.48 _{Sc2O3 ​} 0.00 0.00 0.00 0.00 0.00 .— _{Y2O3 ​} 0.00 0.00 4.00 7.00 0.00 .— _ZrO2 0.00 0.00 0.00 0.00 0.00 .— _{Nb2O5 ​} 0.00 0.00 0.00 0.00 0.00 .— La ₂ O ₃ 0.00 0.00 3.00 0.00 0.00 .— _{Ga2O3 ​} 0.00 2.00 0.00 0.00 6.00 .— _{Ta2O5 ​} 0.00 0.00 0.00 0.00 0.00 .— _{V2O5 ​} 0.00 4.00 0.00 0.00 0.00 .— Property .— Fiberization Temperature (°F) 2350 (1287.8 °C) 2392 (1311.1 °C) 2277 (1247.2 °C) 2338 (1281.1 °C) 2403 (1317.2 °C) 2324 (1273.3 °C) Liquidus temperature (°F) 2241 (1227.2 °C) 2346 (1285.6 °C) 2293 (1256.1 °C) 2130 (1165.6 °C) 2380 (1304.4 °C) 2140 (1171.1 °C) ΔΤ (°F) PO (61.1 °C) 47 (26.1 °C) -16 (-8.9 °C) 208 (115.6 °C) 28 (15.6 °C) 184 (102.2 °C) Density (g/cm ³ ) 2,581 2,533 2,690 2.673 2.605 2,614 Modulus of elasticity (GPa) 90.6 88.9 94.1 93.5 91.0 87.5 Specific modulus (MJ/kg) 35.1 35.1 35.0 35.0 35.0 33.5 Tensile strength (MPa) 4719 — — 4830 4637

Tables 1-8 show the improvement in specific modulus that the glass compositions of the present invention have relative to commercial high-quality glass (comparative example). The comparative example shows a specific modulus of 33.5 MJ/kg, which is below the minimum specific modulus observed for any of the compositions of the present invention. It is instructive that each of the compositions of the present invention exhibits a specific modulus of at least 34 MJ/kg and, more particularly, at least 35 MJ/kg.

The invention of the present application has been described above both generally and with respect to specific embodiments. Although the present invention has been described by what are believed to be preferred embodiments, a wide range of alternatives known to one of ordinary skill in the art may be selected from the general disclosure. The present invention is not otherwise limited except as set forth in the following claims.

Claims (20)

1. Glass composition containing: SiO2 in an amount from 50.0 to 55.5% wt.%; Al2O ₃ in an amount from 19.5 to 23.0 wt.%; CaO in an amount from 2.0 to 9.0 wt.%; MgO in an amount from 9.0 to 14.0 wt.%; SrO in an amount from 0.0 to 1.0 wt.%; Na ₂ O in an amount from 0.0 to 1.0 wt.%; K2O in an amount from 0.0 to <1.0 wt.%; Li ₂ O in an amount from 1.0 to 4.0 wt.%; TiO ₂ in an amount from 0.0 to 4.0 wt.%; Y2O3 in an amount from 0 to 10.0 wt.%; La ₂ O ₃ in an amount from 0 to 10.0 wt.%; Ce ₂ O ₃ in an amount from 0 to 2.5 wt.% and Sc ₂ O ₃ in an amount from 0 to 4.0 wt.%, and the glass composition has a MgO/(CaO+SrO) ratio greater than 2.1. - 15 046930 2. The glass composition according to claim 1, additionally containing: from 0 to about 5.0 wt.% Ta ₂ O ₅ ; from 0 to about 7.0 wt.% Ga ₂ O ₃ ; from 0 to about 5.0 wt.% Nb ₂ O ₅ and from 0 to about 5.0 wt.% V ₂ O ₅ . 3. The glass composition according to claim 2, wherein said composition contains from 1.0 to 3.5 wt.% Y2O3. 4. The glass composition according to any one of claims 1-3, in which the total amount of MgO and CaO is from 12.0 to 20 wt.%. 5. The glass composition according to any one of claims 1 to 4, wherein said composition contains from 19.5 to 22.0 wt.% AW 6. The glass composition according to any one of claims 1 to 5, wherein said composition is substantially free of one or more of B ₂ O ₃ , F, K2O and Na ₂ O. 7. The glass composition according to any one of claims 1 to 6, wherein said composition contains from 0.1 to 3.5 wt.% Li ₂ O. 8. The glass composition according to any one of claims 1 to 7, wherein said composition contains less than 0.05 wt.% Sm ₂ O ₃ +Gd ₂ O ₃ . 9. The glass composition according to any one of claims 1 to 8, wherein the composition contains at least 1 wt.% of the total amount of Y ₂ O ₃ , La ₂ O ₃ , Ce ₂ O ₃ and SC2O3. 10. The glass composition according to any one of claims 1 to 9, wherein the composition has a fiberization temperature of less than 1454.4°C. 11. Glass fiber formed from the composition according to any one of claims 1 to 10, wherein the glass fiber has a specific modulus of elasticity from 34.0 to 40.0 MJ/kg, a tensile strength according to ASTM D2343-09 of at least 4400 MPa and a temperature fiber formation less than 1371.1°C. 12. Glass fiber according to claim 11, in which the glass composition contains from 1.0 to 5.0 wt.% CaO. 13. Glass fiber according to any one of claims 11 to 12, wherein said composition is substantially free of one or more of B2O3, F, K2O and Na2O. 14. Glass fiber according to any one of claims 11-13, in which the specified composition contains from 1.5 to 3.5 wt.% Li2O. 15. Glass fiber according to any one of claims 11-14, in which the composition contains at least 1 wt.% of the total amount of Y ₂ O ₃ , La ₂ O ₃ , Ce ₂ O ₃ and Sc ₂ O ₃ . 16. Glass fiber according to any one of claims 11-15, in which the composition contains more than 2.0 wt.% CeO ₂ +Sc ₂ O ₃ . 17. Glass fiber according to any one of claims 11 to 16, wherein said glass fiber has a specific modulus of elasticity from 35 to 36.5 MJ/kg. 18. A method for producing continuous glass fiber, comprising: providing the molten composition of claim 1 and drawing said molten composition through the opening to form a continuous glass fiber. 19. Reinforced composite product containing: a polymer matrix, and a plurality of glass fibers obtained from the glass composition according to any one of claims 1 to 10, wherein the glass composition has a MgO/(CaO+SrO) ratio of more than 2.1, and the glass fibers have a specific elastic modulus of 34.0 to 40, 0 MJ/kg and fiberization temperature less than 1371.1°C. 20. The reinforced composite product of claim 19, wherein said reinforced composite product is in the form of a wind turbine blade.