Fiber reinforced material with improved fatigue performance

Abstract

A unidirectional laminate comprising a fiber-reinforced composite material having a principal relaxation temperature (Tα) in the range of approximately 110°C to 140°C. The composite material comprises multiple unidirectional reinforcing fibers coated with an adhesive composition and a matrix resin. The unidirectional laminate has a tensile modulus of at least 450 GPa when the fiber volume fraction is greater than or equal to 50% and fatigue mechanical properties of at least 450 MPa at 1 mm cycles, measured according to ASTM E 739-91.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and any benefit to European Patent Application No. 19214303.0, filed on December 6, 2019, the entire contents of which are incorporated herein by reference.

[0003] field

[0004] The overall inventive concept described herein relates to fiber-reinforced composite materials, and more particularly to unidirectional laminates with improved tensile and fatigue properties.

[0005] background

[0006] Reinforcing fibers are used in a variety of products. Fibers can be used as reinforcements in products such as laminated parts, reinforced paper and tape, and woven products. During the fiber forming and collecting process, multiple fibers are bundled together as strands. Several strands can be clustered together to form fiber bundles for reinforcing polymer matrices to provide structural support for products such as molded plastic products.

[0007] Reinforced glass strands are typically prepared by mechanically drawing a flow of molten glass through gravity from multiple holes in a sleeve filled with molten glass to form filaments, which are then aggregated to form base strands and collected. During the drawing process of the glass filaments, and before they are aggregated to form strands, the filaments are often coated with an adhesive composition, typically an aqueous adhesive composition, using a rotating roller. The adhesive composition (also called "adhesive") is conventionally applied during the manufacture of the glass filaments to protect them from wear caused by friction at high speeds during forming and subsequent processes, thus acting as a lubricant. It also removes or prevents electrostatic charges generated during such friction. Additionally, during the production of the reinforced composite, the adhesive improves the wetting of the glass and the impregnation of the strands by passing the material to be reinforced.

[0008] After the reinforcing fibers are produced, they are often processed on a loom or other weaving equipment to produce a reinforced fabric. Many reinforced fabrics consist of longitudinal fibers (warp fibers) arranged side-by-side and substantially parallel to each other, as well as transverse fibers (weft fibers). A unidirectional fabric is a fabric in which at least approximately 80% of the total fibers are in a single direction, typically in the warp direction (also known as the loading direction of the laminate). Therefore, if a unidirectional fabric includes weft fibers, they typically comprise less than 20% of the total fibers in the fabric and provide a backing structure to allow for knitting / sewing of the fabric, thus providing a stable textile structure.

[0009] As noted above, fabrics can be used to form fiber-reinforced structural components. For example, fabrics can be stacked or otherwise laminated to form the spar caps of wind turbine blades. In particular, several layers of fabric can be overlapped to form laminated structural components. The fabric layers are arranged in specific areas and regions of a mold. The impregnation process introduces a curable matrix material (resin) into the mold to penetrate the fabric layers. A vacuum can be applied to the mold during the impregnation process to press the laminations together and help the resin penetrate the layers. Once the fabric is fully impregnated, the resin hardens to form the structural component.

[0010] Components reinforced with such fibers typically require high tensile and fatigue properties. For example, the spars caps of wind turbine blades must withstand near-constant stresses from a considerable number of forces (e.g., wind, centrifugal force) throughout their service life. It remains necessary to increase the modulus of the laminated component within the fiber weight fraction (FWF) range while maintaining or improving fatigue performance.

[0011] Overview

[0012] The overall inventive concept discussed herein is based, at least in part, on the manufacture of a unidirectional laminate comprising: a fiber-reinforced composite material having a principal relaxation temperature (Tα) in the range of about 110°C to 140°C. The composite material comprises a plurality of unidirectional reinforcing fibers coated with an adhesive composition and a matrix resin. The unidirectional laminate has a tensile modulus of at least 45 GPa with a fiber volume fraction greater than or equal to 50% and fatigue mechanical properties of at least 450 MPa at 1 mm cycles, measured according to ASTM E 739-91.

[0013] In one embodiment, the unidirectional laminate may comprise a fiber-reinforced composite material having a storage modulus reduction (ΔE') between about 15 and 35 GPa, the composite material comprising a plurality of unidirectional reinforcing fibers coated with an adhesive composition and a matrix resin, wherein the unidirectional laminate has a tensile modulus of at least 45 GPa when the fiber volume fraction is greater than or equal to 50% and fatigue mechanical properties of at least 450 MPa at 1 mm cycles, measured according to ASTM E 739-91.

[0014] In one embodiment, the unidirectional laminate may comprise a fiber-reinforced composite material having a primary relaxation temperature (Tα) in the range of about 110°C and 140°C and a storage modulus reduction (ΔE') in the range of about 15 and 35 GPa. The composite material comprises a plurality of unidirectional reinforcing fibers coated with an adhesive composition and a matrix resin. The unidirectional laminate has a tensile modulus of at least 45 GPa when the fiber volume fraction is greater than or equal to 50% and fatigue mechanical properties of at least 450 MPa at 1 mm cycles, as measured according to ASTM E 739-91.

[0015] In some exemplary embodiments, the reinforcing fiber is glass fiber, carbon fiber, or a mixture thereof. In some exemplary embodiments, the reinforcing fiber may be glass fiber. In embodiments containing glass fiber, such fiber may have an elastic modulus of at least about 85 GPa. Optionally, the glass fiber may have an elastic modulus of at least about 88 GPa. Optionally, the glass fiber may have an elastic modulus of at least about 89 GPa. The glass fiber may have a tensile strength of at least 3500 GPa.

[0016] In some exemplary embodiments, the glass fiber may have a glass composition comprising one or more oxides selected from the group consisting of SiO2, Al2O3, MgO, and CaO. In some exemplary embodiments, the glass fiber may have a glass composition comprising one or more oxides selected from the group consisting of SiO2, Al2O3, MgO, CaO, Na2O, TiO2, Fe2O3, and Li2O.

[0017] In some exemplary embodiments, the glass fiber may have a glass composition comprising about 55 wt% to about 65 wt% SiO2. Optionally, the glass composition may comprise about 57 wt% to about 62 wt% SiO2. Optionally, the glass composition may comprise about 57.5 wt% to about 60 wt% SiO2.

[0018] In some exemplary embodiments, the glass fiber may have a glass composition comprising about 17 wt% to about 27 wt% Al2O3. Optionally, the glass composition may comprise about 19 wt% to about 25 wt% Al2O3. Optionally, the glass composition may comprise about 19.5 wt% to about 21 wt% Al2O3.

[0019] In some exemplary embodiments, the glass fiber may have a glass composition comprising about 8 wt% to about 15 wt% MgO. Optionally, the glass composition may comprise about 10.5 wt% to about 14 wt% MgO. Optionally, the glass composition may comprise about 11 wt% to about 13 wt% MgO.

[0020] In some exemplary embodiments, the weight percentage ratio of Al2O3 to MgO in the glass composition may be no greater than 2.0. Optionally, the weight percentage ratio of Al2O3 to MgO in the glass composition may be no greater than 1.9. Optionally, the weight percentage ratio of Al2O3 to MgO in the glass composition may be no greater than 1.8.

[0021] In some exemplary embodiments, the glass fiber may have a glass composition comprising about 7 wt% to about 12 wt% CaO. Optionally, the glass composition may comprise about 7.5 wt% to about 10 wt% CaO. Optionally, the glass composition may comprise about 8 wt% to about 9.5 wt% CaO.

[0022] In some exemplary embodiments, the weight percentage ratio of MgO to CaO in the glass composition is at least 1.2. Optionally, the weight percentage ratio of MgO to CaO in the glass composition is at least 1.25.

[0023] In some exemplary embodiments, the glass fiber may have a glass composition comprising about 0 wt% to about 1 wt% Na₂O. Optionally, the glass composition may comprise about 0 wt% to about 0.5 wt% Na₂O. Optionally, the glass composition may comprise about 0.02 wt% to about 0.25 wt% Na₂O. Optionally, the glass composition may comprise no more than 1 wt% Na₂O. Optionally, the glass composition may comprise no more than 0.5 wt% Na₂O.

[0024] In some exemplary embodiments, the glass fiber may have a glass composition comprising from about 0 wt% to about 2 wt% TiO2. Optionally, the glass composition may comprise from about 0.2 wt% to about 1.5 wt% TiO2. Optionally, the glass composition may comprise from about 0.5 wt% to about 1.2 wt% TiO2. Optionally, the glass composition may comprise no more than 2 wt% TiO2.

[0025] In some exemplary embodiments, the glass fiber may have a glass composition comprising from about 0 wt% to about 2 wt% Fe2O3. Optionally, the glass composition may comprise from about 0 wt% to about 1 wt% Fe2O3. Optionally, the glass composition may comprise from about 0 wt% to about 0.5 wt% Fe2O3. Optionally, the glass composition may comprise no more than 2 wt% Fe2O3. Optionally, the glass composition may comprise no more than 1 wt% Fe2O3. Optionally, the glass composition may comprise no more than 0.5 wt% Fe2O3.

[0026] In some exemplary embodiments, the glass fiber may have a glass composition containing no more than 0.5% by weight of Li₂O. Optionally, the glass composition may contain no more than 0.1% by weight of Li₂O. Optionally, the glass composition may contain no more than 0.05% by weight of Li₂O.

[0027] In some exemplary embodiments, the glass fiber may have a glass composition comprising about 55 wt% to about 65 wt% SiO2, about 17 wt% to about 27 wt% Al2O3, about 8 wt% to about 15 wt% MgO, and about 7 wt% to about 12 wt% CaO. In some exemplary embodiments, the glass fiber may have a glass composition comprising about 55 wt% to about 65 wt% SiO2, about 17 wt% to about 27 wt% Al2O3, about 8 wt% to about 15 wt% MgO, about 7 wt% to about 12 wt% CaO, not more than 1 wt% Na2O, not more than 2 wt% TiO2, not more than 2 wt% Fe2O3, and not more than 0.5 wt% Li2O.

[0028] In some exemplary embodiments, the adhesive composition comprises an epoxy film-forming agent, a silane package, one or more lubricants, and an antistatic agent. In some exemplary embodiments, the adhesive composition further comprises one or more thermoplastic film-forming aids. The thermoplastic film-forming aids may be selected from one or more of the group consisting of unsaturated polyester film-forming aids, functionalized epoxy polyvinyl acetate (PVAc) film-forming aids, and polyvinylpyrrolidone (PVP) film-forming aids. The thermoplastic film-forming aids in the adhesive composition may be present in an amount of about 1 to about 10% by weight solids. In some exemplary embodiments, the adhesive composition further comprises a boron-containing compound.

[0029] Additionally, in some exemplary embodiments, the reinforced composite material exhibits a reduction in storage modulus (ΔE') between approximately 15 and 35 GPa.

[0030] In one embodiment, the unidirectional laminate may include:

[0031] i. Fiber-reinforced composite materials, comprising:

[0032] a. Multiple unidirectional reinforcing fibers coated with an adhesive composition; and

[0033] b. Matrix resin,

[0034] The unidirectional laminated part has a tensile modulus of at least 45 GPa when the fiber volume fraction is greater than or equal to 50% and a fatigue mechanical property of at least 450 MPa at 1 mm cycles, as measured according to ASTM E 739-91.

[0035] In one embodiment, the unidirectional laminate may include:

[0036] i. Fiber-reinforced composite materials, comprising:

[0037] a. Multiple unidirectional reinforcing fibers coated with an adhesive composition; and

[0038] b. Matrix resin,

[0039] The reinforcing fiber is a glass fiber having a glass composition comprising about 55 wt% to about 65 wt% SiO2, about 17 wt% to about 27 wt% Al2O3, about 8 wt% to about 15 wt% MgO and about 7 wt% to about 12 wt% CaO, and the sizing composition comprises an epoxy film-forming agent, a silane package, one or more lubricants and an antistatic agent.

[0040] However, it should be understood that the glass fiber and sizing composition can be selected from any glass fiber and sizing composition as described herein.

[0041] Another exemplary aspect of the present invention relates to a wind turbine blade comprising a unidirectional laminate comprising a plurality of unidirectional reinforcing fibers coated with an adhesive composition and a cured matrix resin. The unidirectional laminate has a modulus of at least 45 GPa at a fiber volume fraction greater than or equal to 50% and fatigue mechanical properties of at least 450 MPa at 1 mm cycles, measured according to ASTM E 739-91.

[0042] In some exemplary embodiments, the reinforcing fiber is glass fiber, carbon fiber, or a mixture thereof. In embodiments containing glass fiber, such fiber may have an elastic modulus of at least about 85 GPa, including at least about 88 GPa, or at least about 89 GPa. The glass fiber may have a tensile strength of at least 3500 GPa.

[0043] In some exemplary embodiments, the adhesive composition comprises an epoxy film-forming agent, a silane package, one or more lubricants, and an antistatic agent. In some exemplary embodiments, the adhesive composition further comprises one or more thermoplastic film-forming aids, such as unsaturated polyester film-forming aids, functionalized epoxy polyvinyl acetate (PVAc) film-forming aids, or polyvinylpyrrolidone (PVP) film-forming aids. The thermoplastic film-forming aids in the adhesive composition may be present in an amount of about 1 to about 10% by weight solids. In some exemplary embodiments, the adhesive composition further comprises a boron-containing compound.

[0044] The features and implementation schemes described herein are adapted, as appropriate, to each and every aspect and each and every implementation scheme thereof.

[0045] Other aspects, advantages, and / or features of the overall inventive concept will become more readily apparent from the following detailed description of exemplary embodiments and from the accompanying drawings.

[0046] Brief description of the attached diagram

[0047] The overall inventive concept, its implementation scheme, and its advantages are described in more detail below with reference to the accompanying drawings and examples, wherein:

[0048] Figure 1 This describes a conventional system for forming structural laminates made of composite materials.

[0049] Figure 2 The relationship between the modulus of laminated parts and the fiber volume fraction of laminated parts is illustrated graphically using theoretical and experimental models.

[0050] Figure 3 The properties of DMA, the range of principal relaxation temperature (Tα), and the storage modulus (ΔE') are illustrated graphically.

[0051] Detailed description

[0052] Various exemplary embodiments will now be described in more complete form, with reference occasionally to the accompanying drawings. However, these exemplary embodiments may be implemented in different forms and should not be construed as limiting themselves to the description set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be comprehensive and complete, and will convey the overall inventive concept to those skilled in the art.

[0053] Unless otherwise specified, 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 pertain. The terminology used in this description is for the purpose of describing particular exemplary embodiments only and is not intended to limit the scope of the exemplary embodiments.

[0054] As used in the specification and appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0055] Unless otherwise stated, all figures used in the specification and claims to indicate amounts of ingredients, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Therefore, unless indicated to the contrary, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending on the desired properties sought to be obtained through the exemplary embodiments described herein. At least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be interpreted according to the number of significant figures and ordinary rounding.

[0056] While the numerical ranges and parameters described in the exemplary embodiments are approximate, the values ​​described in the specific embodiments are reported as precisely as possible. However, any numerical value inherently contains some error that is necessarily caused by the standard deviation found in their respective test measurements. Each numerical range given throughout the specification and claims will include each narrower numerical range falling within such a wider range, as such narrower numerical ranges are also expressly stated herein. Furthermore, any numerical values ​​reported in the embodiments may be used to define the upper or lower endpoints of the wider range of components disclosed herein.

[0057] As the exploration of alternative energy sources continues, wind power and the use of wind turbines have gained increasing attention. Many consider wind power a clean and environmentally friendly energy source. With growing interest in generating more energy from wind, technological advancements in the field have allowed for larger wind turbines and new designs for wind turbine components. However, as the physical size and availability of wind turbines increase, the need to design components that balance high strength-to-weight ratio and long component life to further allow wind power to be cost-competitive with other energy sources is also growing.

[0058] The size, shape, and weight of turbine blades significantly contribute to the cost and energy efficiency of wind turbines. Increasing blade size and decreasing blade weight generally improves the energy efficiency of wind turbines. However, increasing blade size also contributes to additional forces associated with turbine operation. This increase in forces leads to increased strain and fatigue on the blade components, which in turn reduces blade life.

[0059] The structural components of a wind turbine blade include a matrix (typically a cured resin) and reinforcing materials. The reinforcing materials comprise fibrous fabrics. Reinforcing fibers used in the manufacture of wind turbine blade materials include glass fibers, carbon fibers, and mixtures thereof. It is known in the art that bare glass fibers are incompatible with many common resins. That is, the resin will not cure and bond with the glass. The resulting composite material will consist of two materials, but without strong adhesion between them, and the composite material will not function. This problem is overcome by applying a “glue” to the glass before exposing it to the resin.

[0060] Adhesives are chemical compositions (often liquid or aqueous) applied to the surface of glass during the production of glass fibers. Adhesives serve many purposes, one of which is to form a chemical "bridge" between the resin and glass surfaces, making them chemically compatible and promoting bonding between them, which in turn results in a stronger composite material. Therefore, adhesives will include chemical functional groups, one of which interacts with the glass and another with the resin.

[0061] This invention is based, at least in part, on the discovery that the tensile and fatigue properties of unidirectional laminates are controlled by key viscoelastic properties of the unidirectional composite material, such as the principal relaxation temperature Tα (f = 1 Hz) and the reduction in storage modulus ΔE' (defined as E' glassy – E' rubbery, normalized to 50% fiber weight fraction (FVF)). These viscoelastic properties can be tuned in various ways, for example, by using high-modulus glass fibers, special sizing chemicals, or combinations thereof. In some exemplary embodiments, particularly optimized viscoelastic properties are achieved by using a combination of high-modulus glass fibers and high-performance sizing chemicals. By optimizing the viscoelastic properties of the unidirectional composite material, unidirectional laminates can be produced having a modulus of at least 45 GPa at a fiber weight fraction (FWF) greater than or equal to 50% and fatigue mechanical properties (at stress levels extrapolated at 1 mm cycles) of at least 450 MPa as measured according to ISO 13003 (testing) and ASTM E739-91 (data analysis).

[0062] Reinforcing fibers

[0063] In some exemplary embodiments, the unidirectional fabric includes one or more reinforcing fibers, which may comprise glass fibers, carbon fibers, or a mixture of glass fibers and carbon fibers. In some exemplary embodiments, the reinforcing fibers comprise bundles of glass fibers used in a continuous or discontinuous form. In some exemplary embodiments, the reinforcing fiber bundles comprise continuous fibers in the form of unbroken filaments, yarns, strands, tufts, or rovings.

[0064] The glass can be any conventional glass composition, such as silica-based glass, borosilicate glass such as E-glass, high-strength glass such as S-glass, H-glass, R-glass, E-type glass with a lower boron content, or boron-free glass, E-CR glass (e.g., available from Owens Corning). Glass) and high modulus glass.

[0065] The reinforcing fibers may have an average diameter ranging from about 6 micrometers to about 30 micrometers, including between about 10 micrometers and 25 micrometers, between about 12 micrometers and 24 micrometers, and between about 14 micrometers and 20 micrometers. The reinforcing fibers may comprise one or more fiber bundles having a bundle tex of about 100 to about 5000, including between about 200 and 4900, and between about 300 and 4800. In some exemplary embodiments, the reinforcing fibers have an average diameter of 15 micrometers to 18 micrometers. In some exemplary embodiments, the reinforcing fibers have a bundle tex of 2300 to 2500 tex. In some exemplary embodiments, the reinforcing fibers have an average diameter of 15 micrometers to 18 micrometers and a bundle tex of 2300 to 2500 tex.

[0066] As mentioned above, one way to adjust the viscoelastic properties of unidirectional laminates is to select high-modulus glass fibers. "High-modulus glass fiber" means glass fiber that achieves an elastic modulus of at least about 85 GPa, measured according to the acoustic measurement procedures outlined in the report "Glass Fiber and Measuring Facilities at the U.S. Naval Ordnance Laboratory" (NOLTR 65-87, June 23, 1965). In some exemplary embodiments, the high-modulus glass fibers have elastic moduli of at least about 88 GPa, at least about 88.5 GPa, at least about 89 GPa, and at least about 89.5 GPa.

[0067] High-modulus glass fibers may be of the type described in WO2019126252A1.

[0068] In some exemplary embodiments, the glass composition comprises about 55.0 to about 65.0 wt% SiO2, about 17.0 to about 27.0 wt% Al2O3, about 8.0 to about 15.0 wt% MgO, about 7.0 to about 12.0 wt% CaO, about 0.0 to about 1.0 wt% Na2O, 0 to about 2.0 wt% TiO2, 0 to about 2.0 wt% Fe2O3, and not more than 0.5 wt% Li2O. Advantageously, the weight percentage ratio of alumina to magnesium oxide (Al2O3 / MgO) is not greater than 2.0, for example, not greater than 1.9 and not greater than 1.8. Additionally, the weight percentage ratio of magnesium oxide to calcium oxide (MgO / CaO) is advantageously at least 1.2.

[0069] In some exemplary embodiments, the glass composition may comprise about 57.0 to about 62.0 wt% SiO2, about 19.0 to about 25.0 wt% Al2O3, about 10.5 to about 14.0 wt% MgO, about 7.5 to about 10.0 wt% CaO, about 0.0 to about 0.5 wt% Na2O, 0.2 to about 1.5 wt% TiO2, 0 to about 1.0 wt% Fe2O3, and not more than 0.1 wt% Li2O. In some exemplary embodiments, the glass composition includes an Al2O3 / MgO ratio of less than 2 and an MgO / CaO ratio of at least 1.25.

[0070] In some exemplary embodiments, the glass composition may comprise about 57.5 to about 60.0 wt% SiO2, about 19.5 to about 21.0 wt% Al2O3, about 11.0 to about 13.0 wt% MgO, about 8.0 to about 9.5 wt% CaO, about 0.02 to about 0.25 wt% Na2O, 0.5 to about 1.2 wt% TiO2, 0 to about 0.5 wt% Fe2O3, and not more than 0.05 wt% Li2O. In some exemplary embodiments, the glass composition includes an Al2O3 / MgO ratio of not more than 1.8 and an MgO / CaO ratio of at least 1.25.

[0071] The glass composition comprises at least 55 wt% but not more than 65 wt% SiO2. Containing more than 65 wt% SiO2 causes an unfavorable increase in the viscosity of the glass composition. Furthermore, containing less than 55 wt% SiO2 increases the liquidus temperature and crystallization tendency. In some exemplary embodiments, the glass composition comprises at least 57 wt% SiO2, including at least 57.5 wt%, at least 58 wt%, at least 58.5 wt%, and at least 59 wt%. In some exemplary embodiments, the glass composition comprises no more than 60.5 wt% SiO2, including no more than 60.3 wt%, no more than 60.2 wt%, no more than 60 wt%, no more than 59.8 wt%, and no more than 59.5 wt%.

[0072] In some exemplary embodiments, the glass composition has an Al2O3 concentration of at least 19.0 wt% and no more than 27 wt%. Including more than 27 wt% Al2O3 causes the glass liquidus line to rise above the fiberization temperature, resulting in a negative ΔT. Including less than 19 wt% Al2O3 forms glass fibers with an unfavorably low modulus. In some exemplary embodiments, the glass composition includes at least 19.5 wt% Al2O3, including at least 19.7 wt%, at least 20 wt%, at least 20.25 wt%, and at least 20.5 wt%.

[0073] The glass composition advantageously includes at least 8.0 wt% and no more than 15 wt% MgO. Including more than 15 wt% MgO will cause an increase in the liquidus line, which also increases the glass's tendency to crystallize. If replaced by CaO, less than 8.0 wt% forms glass fibers with an unfavorably low modulus, and if replaced by SiO2, less than 8.0 wt% forms glass fibers with an unfavorably increased viscosity. In some exemplary embodiments, the glass composition includes at least 9.5 wt% MgO, including at least 10 wt%, at least 10.5 wt%, at least 11 wt%, at least 11.10 wt%, at least 11.25 wt%, at least 12.5 wt%, and at least 13 wt% MgO.

[0074] Another important aspect of the subject glass composition that enables the desired mechanical and fibrous properties is having an Al₂O₃ / MgO ratio of no more than 2.0. Glass fibers with compositions having similar ranges but an Al₂O₃ / MgO ratio greater than 2.0 have been found to fail to achieve a tensile strength of at least 4800 MPa. In some exemplary aspects, a combination of at least 19% by weight Al₂O₃ concentration and an Al₂O₃ / MgO ratio of no more than 2, for example, no more than 1.9 and no more than 1.85, can yield glass fibers with the desired fibrous properties and a tensile strength of at least 4800 MPa.

[0075] The glass composition advantageously includes at least 7.0 wt% and no more than 12 wt% CaO. Including more than 12 wt% CaO forms a glass with a low elastic modulus. Depending on what CaO is replaced, including less than 7 wt% will adversely increase the liquidus temperature or viscosity. In some exemplary embodiments, the glass composition includes at least 8.0 wt% CaO, including at least 8.3 wt%, at least 8.5 wt%, at least 8.7 wt%, and at least 9.0 wt%.

[0076] In some exemplary embodiments, the total amount of SiO2, Al2O3, MgO, and CaO in the glass composition is at least 98 wt%, or at least 99 wt% and not more than 99.5 wt%. In some exemplary embodiments, the total amount of SiO2, Al2O3, MgO, and CaO is between 98.3 wt% and 99.5 wt%, including between 98.5 wt% and 99.4 wt% and between 98.7 wt% and 99.3 wt%.

[0077] In some exemplary embodiments, the total concentration of MgO and CaO in the glass composition is at least 10% by weight and no more than 22% by weight, including between 13% by weight and 21.8% by weight and between 14% by weight and 21.5% by weight. In some exemplary embodiments, the total concentration of MgO and CaO is at least 20% by weight.

[0078] The glass composition may include up to about 2.0 wt% TiO2. In some exemplary embodiments, the glass composition includes about 0.01 wt% to about 1.0 wt% TiO2, including about 0.1 wt% to about 0.8 wt% and about 0.2 wt% to about 0.7 wt%.

[0079] The glass composition may include up to about 2.0 wt% Fe2O3. In some exemplary embodiments, the glass composition includes about 0.01 wt% to about 1.0 wt% Fe2O3, including about 0.05 wt% to about 0.6 wt% and about 0.1 wt% to about 0.5 wt%.

[0080] In some exemplary embodiments, the glass composition includes less than 2.0 wt% of alkali metal oxides Na₂O and K₂O, ranging from 0 to 1.5 wt%. The glass composition may include both Na₂O and K₂O in amounts greater than 0.01 wt% of each oxide. In some exemplary embodiments, the glass composition includes about 0 to about 1 wt% Na₂O, comprising 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 some exemplary embodiments, the glass composition includes about 0 to about 1 wt% K₂O, comprising about 0.01 to about 0.5 wt%, about 0.03 to about 0.3 wt%, and 0.04 to about 0.1 wt%.

[0081] As used herein, the terms “percentage by weight,” “% by weight,” “weight%,” and “percentage by weight” are used interchangeably and are intended to indicate a percentage by weight (or percentage by weight) based on the total composition.

[0082] The glass composition may be free of or substantially free of B2O3, Li2O, and fluorine, but any one or more may be added in small amounts to adjust the properties of the fiberized and finished glass, and if maintained below a few percentages, the properties will not be adversely affected. As used herein, substantially free of B2O3, Li2O, and fluorine means a composition in which the sum of the amounts of B2O3, Li2O, and fluorine present is less than 1.0 wt%. The sum of the amounts of B2O3, Li2O, and fluorine present may be less than about 0.5 wt%, including less than about 0.2 wt%, less than about 0.1 wt%, and less than about 0.05 wt%.

[0083] The glass composition may also include impurities and / or trace materials without adversely affecting the glass or fibers. These impurities may enter the glass as raw material impurities or may be products formed by the reaction of molten glass with furnace components. Non-limiting examples of trace materials include zinc, strontium, barium, and combinations thereof. Trace materials may be present in the form of their oxides and may also include fluorine and / or chlorine. In some exemplary embodiments, the glass composition of the invention contains less than 1.0 wt%, including less than 0.5 wt%, less than 0.2 wt%, and less than 0.1 wt% of each of BaO, SrO, ZnO, ZrO2, P2O5, and SO3. In particular, the glass composition may include less than about 5.0 wt% of BaO, SrO, ZnO, ZrO2, P2O5, and / or SO3 in total, wherein if each of BaO, SrO, ZnO, ZrO2, P2O5, and SO3 is present, it is present in an amount of less than 1.0 wt%.

[0084] Fiber tensile strength is also referred to herein simply as "strength". In some exemplary embodiments, tensile strength is measured in virgin form (i.e., un-glued and uncontacted laboratory-produced fibers) using an Instron tensile testing apparatus according to ASTM D2343-09. Exemplary glass fibers formed from the glass compositions of the present invention described above may have a fiber tensile strength of at least 3500 MPa, including at least 4000 MPa, at least 4500 MPa, at least 4800 MPa, at least 4900 MPa, at least 4950 MPa, at least 5000 MPa, at least 5100 MPa, at least 5150 MPa, and at least 5200 MPa. In some exemplary embodiments, glass fibers formed from the compositions described above have a fiber tensile strength of about 3500 to about 5500 MPa, including about 4000 MPa to about 5300 MPa, and about 4600 to about 5250 MPa.

[0085] Glass fibers can be formed by any means known in the art and conventionally used. In some exemplary embodiments, glass fibers are formed by obtaining raw material components and mixing the components in appropriate amounts to obtain the desired weight percentage of the final composition.

[0086] The components of the glass composition can be obtained from suitable ingredients or raw materials, including but not limited to sand or pyrophyllite for SiO2, limestone, quicklime, wollastonite, or dolomite for CaO, kaolin, alumina, or pyrophyllite for Al2O3, dolomite, dolomitic quicklime, brucite, enstatite, talc, calcined magnesite, or magnesite for MgO, and sodium carbonate, albite, or sodium sulfate for Na2O. In some exemplary embodiments, cullet may be used to provide one or more desired oxides.

[0087] In some exemplary embodiments, continuous glass fibers are formed by drawing molten glass filaments from a sleeve and coating the glass filaments with an adhesive composition before bundling them into bundles, thereby forming fiber bundles.

[0088] Adhesive composition

[0089] When high-modulus glass fibers with an elastic modulus of at least 85 GPa are used in unidirectional laminates, the grouting composition may comprise any conventional grouting composition known in the art, such as Owens Corning grouting compositions: SE1500, WS 3000, WS2000, WS3200 and SE1200.

[0090] However, as mentioned above, in order to allow the use of a wide variety of glass fiber compositions in the manufacture of unidirectional laminates, another way to adjust the viscoelastic properties of composites is through high-performance adhesive chemicals, such as those disclosed in US8,129,018.

[0091] The high-performance adhesive compositions described herein can be used with any glass composition while still exhibiting improved viscoelastic properties. In some exemplary embodiments, the high-performance adhesive composition includes an epoxy film-forming agent, a silane package comprising an aminosilane coupling agent and an epoxysilane coupling agent, one or more lubricants, and an antistatic agent. In some exemplary embodiments, the high-performance adhesive composition includes an epoxy film-forming agent, a silane package comprising an aminosilane coupling agent and an epoxysilane coupling agent, one or more lubricants, an antistatic agent, and at least one acid. Additionally, the high-performance adhesive composition may also contain polyurethane or an epoxy / polyurethane film-forming agent.

[0092] In some exemplary embodiments, the high-performance sizing composition includes an epoxy film-forming polymer component. The epoxy film-forming polymer component of the sizing composition may comprise an epoxy resin emulsion containing a low molecular weight epoxy resin and at least one surfactant. The film-forming agent serves to protect the fibers from damage during processing and imparts compatibility between the fibers and the matrix resin. In some exemplary embodiments, the epoxy resin has a molecular weight of 360-420 and an epoxy equivalent weight of 180-210, or a molecular weight of 360-390 and an epoxy equivalent weight of 180-195, and / or a molecular weight of 370-384 and an epoxy equivalent weight of 185-192. As used herein, “epoxy equivalent weight” is defined by dividing the molecular weight of the epoxy resin by the number of epoxy groups present in the compound. Available epoxy resins contain at least one epoxy or epoxy ethylene group in the molecule, such as polyglycidyl ethers of polyols or thiols. Examples of suitable epoxy film-forming resins include… 828 (available from Hexion Specialties Chemicals Incorporated), DER 331 (available from Dow Chemicals), Araldite 6010 (available from Huntsman), and Epotuf 37-140 (available from Reichhold Chemical Co.) and similar commercially available emulsions such as Epi-rez 3510-w-60 and Epi-rez 3522-w-60, both from Hexion.

[0093] In some exemplary embodiments, the high-performance sizing composition includes one or more thermoplastic film-forming aids, such as unsaturated polyester film-forming aids, functionalized epoxy polyvinyl acetate (PVAc) film-forming aids, and polyvinylpyrrolidone (PVP) film-forming aids, such as Resyn 1037 from Celanese and PVP K90 from Ashland, respectively. In some exemplary embodiments, the film-forming aid is present in the sizing composition at an amount of about 1 to about 10% by weight solids, based on the total solids content of the sizing composition. In some exemplary embodiments, the film-forming aid is present in the sizing composition at an amount of about 2 to about 9% by weight solids. In some exemplary embodiments, the film-forming aid is present in the sizing composition at an amount of about 3 to about 8% by weight solids.

[0094] Examples of suitable surfactants for use in epoxy resin emulsions include, but are not limited to, Triton X-100, an octylphenoxy polyethoxyethanol (available from Union Carbide Corp.), Pluronic P103, an ethylene oxide / propylene oxide block copolymer (available from BASF), Pluronic F77, an ethylene oxide / propylene oxide block copolymer (available from BASF), Pluronic 10R5, an ethylene oxide / propylene oxide block copolymer (available from BASF), block copolymers of ethylene oxide and propylene oxide such as Pluronic L101 (available from BASF), polyoxyethylene-polyoxypropylene block copolymers such as Pluronic P105 (available from BASF), and ethylene oxide / propylene oxide block copolymers (available from BASF). Preferably, the epoxy resin emulsion contains two or more surfactants. In a preferred embodiment, a combination of (1) a block copolymer of ethylene oxide and propylene oxide and (2) a polyoxyethylene-polyoxypropylene block copolymer (e.g., Pluronic L101 and Pluronic P105) is used in the epoxy resin emulsion. One or more surfactants may be present in the epoxy resin emulsion in an amount of 10-25%, or in an amount of 15-20%, for example, about 18%.

[0095] In various exemplary embodiments, the epoxy resin emulsion is present in the high-performance grouting composition in an amount of about 60 to about 90% by weight solids, for example, about 70-80% by weight solids.

[0096] Surfactants, plasticizers, and dispersants may include optionally halogenated aliphatic or aromatic polyalkoxylated compounds, such as ethoxylated / propoxylated alkylphenols or ethoxylated / propoxylated fatty alcohols. These polyalkoxylated compounds may be block or random copolymers; amine-containing compounds such as optionally alkoxylated amines, amine oxides, alkylamides, succinates and taurine esters, sugar derivatives, particularly sugar derivatives of sorbitol, optionally alkoxylated alkyl sulfates, optionally alkylated or alkoxylated alkyl phosphates, and ether phosphates. The sizing composition may also include antistatic agents such as specific organic cationic or nonionic agents such as aliphatic quaternary amines or imidazoline derivatives to prevent static buildup due to friction on guiding devices such as ceramic guide eyes.

[0097] The total amount (dry solids content) of surfactants, plasticizers, dispersants, or combinations thereof in the high-performance adhesive composition may be in the range of about 2% by weight to about 30% by weight, or about 4% by weight to about 20% by weight. In some exemplary embodiments, the surfactant is present at a solids content of about 0.25% by weight to 15% by weight. In some exemplary embodiments, the plasticizer is present at a solids content of 0% to about 10% by weight. In some exemplary embodiments, the dispersant is present at a solids content of about 0.1% by weight to 15% by weight. In some exemplary embodiments, the antistatic agent is present at a solids content of 0% to 8% by weight.

[0098] Coupling agents promote adhesion between the adhesive and the glass surface by inducing covalent bonds with the film-forming agent. In the case of a non-reactive polymer matrix, the coupling agent can further form a covalently bonded or at least interpenetrating network with the polymer matrix. Another function of coupling agents is to form a polysiloxane layer on the glass fiber, which improves durability under corrosive aging conditions such as in humid, acidic, or high-temperature environments. Coupling agents can be hydrolyzable compounds, such as those that can be hydrolyzed in the presence of acids such as acetic acid, lactic acid, citric acid, formic acid, tartaric acid, and oxalic acid.

[0099] In one exemplary embodiment, the coupling agent comprises a silane package including at least one aminosilane coupling agent and at least one epoxysilane coupling agent. The coupling agent used in the silane package of the adhesive composition may have hydrolyzable groups that can react with the glass surface to remove unwanted hydroxyl groups and one or more groups that can react with the film-forming polymer to chemically bond the polymer to the glass surface. In particular, the coupling agent preferably comprises 1-3 hydrolyzable functional groups that can interact with the surface of the glass fiber and one or more organic groups compatible with the polymer matrix.

[0100] Suitable coupling agents for use in silane packages have readily hydrolyzable bonds with the silicon atoms of the silane or its hydrolysis products. Silane coupling agents that can be used in this adhesive composition can be characterized by functional groups such as amino, epoxy, azide, vinyl, methacryloxy, urea, and isocyanate. Additionally, the coupling agent may include acryloyl or methacryl groups linked by non-hydrolyzable bonds to the silicon atoms of the silane.

[0101] Coupling agents used in silane packages include the monosilane-containing structure Si(OR)2, where R is an organic group such as an alkyl group. Lower alkyl groups such as methyl, ethyl, and isopropyl are preferred. Silane coupling agents enhance the adhesion of the film-forming agent to the glass fibers and reduce the level of fuzz or broken fiber filaments during subsequent processing. Examples of suitable aminosilane coupling agents for use in silane packages include, but are not limited to, aminopropyltriethoxysilane (A-1100 from GE Silicones), N-β-aminoethyl-γ-aminopropyltrimethoxysilane (A-1120 from GE Silicones), N-phenyl-γ-aminopropyltrimethoxysilane (Y-9669 from GE Silicones), and bis-γ-trimethoxysilylpropylamine (A-1170 from GE Silicones). Preferably, the aminosilane coupling agent is aminopropyltriethoxysilane (A-1100 from GE Silicones). Aminosilane coupling agents can be present in high-performance sizing compositions at an amount of 0.4-0.8% by weight solids, for example, 0.4-0.6% by weight solids. While not wishing to be bound by theory, it is believed that the presence of even a small amount of aminosilane coupling agent in the sizing composition improves the mechanical properties of the final product. Excessive addition of aminosilane coupling agent to the sizing composition can deteriorate the mechanical properties.

[0102] Non-limiting examples of suitable epoxy silane coupling agents include glycidoxy polymethylene trimekoxy silanes such as 3-glycidoxy-1-propyl-trimethoxy silane, acryloyloxy or methacryloyloxy polymethylene trimekoxy silanes such as 3-methacryloyloxy-1-propyltrimethoxy silane, γ-glycidoxypropyltrimethoxy silane (A-187, available from GE Silicones), γ-methacryloyloxypropyltrimethoxy silane (A-174, available from GE Silicones), α-chloropropyltrimethoxy silane (KBM-703, available from Shin-Etsu Chemical Co., Ltd.), α-glycidoxypropylmethyldiethoxy silane (A-2287, available from GE Silicones), and vinyl-tris-(2-methoxyethoxy)silane (A-172, available from GE Silicones). In at least one preferred embodiment, the epoxy silane coupling agent is γ-glycidoxypropyltrimethoxysilane (A-187) as described above. The use of methacryloxysilanes, such as A-174, improves the compatibility of the sizing fibers with vinyl esters and polyester resins. The epoxy silane coupling agent may be present in the sizing composition in an amount of 10-20% by weight solids, or 10-16% by weight solids, or 10-14% by weight solids.

[0103] In addition, the high-performance sizing composition contains at least one nonionic lubricant. The nonionic lubricant in the sizing composition acts as a “wet lubricant” and provides additional protection to the fibers during the filament winding process. Furthermore, the nonionic lubricant helps reduce fuzz formation. Particularly suitable examples of nonionic lubricants include PEG 200 monolaurate (a polyethylene glycol fatty acid ester, commercially available from Cognis) and PEG 600 monooleate (Cognis). Other non-limiting examples include polyalkylene glycol fatty acids such as PEG 600 monostearate (a polyethylene glycol monostearate, available from Cognis), PEG 400 monostearate (Cognis), PEG 400 monooleate (Cognis), and PEG 600 monolaurate (Cognis). In the most preferred embodiment, the nonionic lubricant is PEG 200 monolaurate. The nonionic lubricant may be present in the sizing composition in an amount of about 6-10% by weight solids, preferably 7-9% by weight solids.

[0104] In addition to nonionic lubricants, the high-performance sizing compositions also contain at least one cationic lubricant and at least one antistatic agent. Cationic lubricants help reduce interfilament friction. Suitable examples of cationic lubricants include, but are not limited to, polyethyleneimine polyamide salts commercially available from Cognis under the trade name Emery 6760L, and stearic acid ethanolamines such as Lubesize K-12 (AOC), Cirrasol 185AE (Unichemie), and Cirrasol 185AN (Unichemie). The amount of cationic lubricant present in the sizing composition is preferably sufficient to provide an active lubricant level that will form a coating with low fuzz development. In at least one exemplary embodiment, the cationic lubricant is present in the sizing composition in an amount of 0.01-1.0% wt% solids, preferably 0.03-0.06% wt% solids. Antistatic agents particularly suitable for use herein include those soluble in the sizing composition. Examples of suitable antistatic agents include compounds such as Emerstat. TM 6660A and Emerstat TM 6665 (a quaternary ammonium antistatic agent available from Emery Industries, Inc.) and Larostat 264A (a quaternary ammonium antistatic agent available from BASF), tetraethylammonium chloride and lithium chloride. The antistatic agent may be present in the sizing composition in an amount of 0.4-0.8% by weight solids, preferably 0.4-0.6% by weight solids.

[0105] The total amount of cationic lubricant and antistatic agent present in the adhesive composition can range from 0.4 to 0.8% by weight solids, preferably 0.4 to 0.7% by weight solids. In some exemplary embodiments, the amount of cationic lubricant and antistatic agent present in the adhesive composition is less than or equal to about 1.0% by weight solids.

[0106] In addition, the high-performance sizing composition may contain a small amount of at least one weak organic acid. While not wishing to be bound by theory, it is believed that citric acid, a conventional acid additive used in sizing compositions for pH adjustment, if used in large quantities during the drying process of glass fibers, can prematurely open the epoxy groups in the film-forming agent and the epoxy silane, which can lead to a decrease in mechanical properties. Trace amounts of acetic acid, formic acid, succinic acid, and / or citric acid may be added to the sizing composition of the invention to hydrolyze the silane in the coupling agent without prematurely opening the epoxy groups. In some exemplary embodiments, the organic acid is acetic acid. The organic acid (e.g., acetic acid) may be present in the sizing composition in an amount of 0.4-1.0% by weight solids or 0.5-0.7% by weight solids.

[0107] Additionally, the high-performance adhesive composition may contain a boron-containing compound capable of providing boron atoms to the adhesive composition. It is presumed that the boron atoms released from the boron-containing compound interact with the aminosilane at the glass interface, thereby aiding in the adhesion of the remaining adhesive composition to the glass fiber. The combination of boron-containing compounds, such as boric acid, in the adhesive composition with aminosilanes (e.g., A-1100) and epoxysilanes (e.g., A-187) improves the mechanical properties of the final product. Non-limiting examples of suitable boron-containing compounds include boric acid and borates such as boron oxide, sodium tetraborate, potassium metaborate, potassium tetraborate, ammonium diborate, ammonium tetrafluoroborate, butylammonium tetrafluoroborate, calcium tetrafluoroborate, lithium fluoroborate, potassium tetrafluoroborate, sodium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, and zinc tetrafluoroborate. In some exemplary embodiments, the boron-containing compound is boric acid. Boron-containing compounds may be present in the sizing composition in an amount of 0.2-3.0% by weight solids, for example 0.2-1.0% by weight solids, or 0.2-0.6% by weight solids.

[0108] The combination of boric acid and organic acid (e.g., acetic acid) in the sizing composition is intended to impart a pH of 3.0-7.0, such as 3.5-5.5, to the sizing composition.

[0109] Optionally, the high-performance adhesive composition may contain polyurethane film-forming agents such as Baybond 2297 (Bayer), Baybond PU403 (Bayer), and W-290H (Chemtura) or epoxy / polyurethane film-forming agents such as Epi-Rez 5520-W-60 (Hexion Specialties Chemicals Incorporated).

[0110] Polyurethane film-forming agents improve strand integrity and mechanical fatigue properties by toughening the resin / resin mesophase. The toughened resin mesophase results in a final composite product with improved crack resistance and enhanced or improved mechanical properties, such as improved strength. The urethane film-forming agent can be present in the sizing composition in an amount of about 2 to about 10% by weight solids, for example, 2.5-7.5% by weight solids or about 5.1% by weight solids. Suitable polyurethane dispersions include polyurethane emulsions, for example, those available from... Technologies, Inc. (Raleigh, NC, USA) U1-01, U1-03, U2-01, U4-01, U5-01, U6-01, U6-03 and U7-01.

[0111] The high-performance sizing composition also includes water to dissolve or disperse the active solids for coating. Water may be added in an amount sufficient to dilute the aqueous sizing composition to a viscosity suitable for its application to glass fibers and achieving the desired solids content on the fibers. The mixed solids content of the sizing composition may be from about 1.0 to about 15%, for example from about 5 to about 10%, or from about 8.0 to about 8.5%. In some exemplary embodiments, the sizing composition may contain up to about 92% water.

[0112] High-performance adhesive compositions may optionally include one or more additives. In some exemplary embodiments, additives include flame retardants, nanoparticles, lubricants such as fatty acid esters, fatty alcohols, fatty amine salts, mineral oils, or mixtures thereof; complexing agents such as EDTA derivatives, gallic acid derivatives, or phosphonic acid derivatives; defoamers such as silicones or vegetable oils; polyols; acids, such as acetic acid, lactic acid, or citric acid, used to control pH during the hydrolysis of the coupling agent; cationic polymers; emulsifiers; viscosity modifiers; stabilizers; acids; and other bases.

[0113] In some embodiments, the total content of additives in the sizing composition is in the range of about 0.1% to about 15% by weight, and in some embodiments it is 1% to 5% by weight (dry extract solids content).

[0114] Unidirectional laminated parts

[0115] Reference Figure 1 A conventional system 100 is described for forming structural laminates made of composite materials. In system 100, machine 102 continuously produces fiber-reinforced material in the form of a refractory fabric 104. The fabric comprises substantially unidirectional fibers, meaning that at least 80% of the fibers extend in a single direction (typically the warp direction). In some exemplary embodiments, the fabric is 100% unidirectional. In some exemplary embodiments, the fabric comprises less than 5% weft fibers, or less than 2% weft fibers, or less than 1% weft fibers. In some exemplary embodiments, the fabric comprises 100% unidirectional and contains no weft fibers.

[0116] As noted above, fabric 104 comprises unidirectional fibers extending substantially along the length of fabric 104 (i.e., parallel to arrow 106). As fabric 104 exits machine 102 and travels in the direction indicated by arrow 106, fabric 104 is wound in roll region 108. A winding machine or other conveying device draws fabric 104 from machine 102 to roll region 108. A blade or other cutting device forms a seam 110 in fabric 104 prior to roll region 108. In this way, separate rolls 112 of fabric 104 are formed.

[0117] Once a predetermined quantity of fabric 104 has been wound onto the roll area 108, a hand cut 114 is made across the width of the fabric 104, thereby separating the roll 112 from the fabric 104 leaving the machine 102. When it is time to form the laminated part, one or more rolls 112 are stacked in a mold (not shown). Once the desired thickness and shape are achieved within the mold, resin is introduced, for example, through an impregnation process, and cured to form the laminated part.

[0118] In some embodiments, the matrix resin comprises a resin selected from the following: polyester resin, vinyl ester resin, polyurethane resin, bio-based resin, and styrene-free resin.

[0119] The unidirectional laminate has a high fiber load of at least 50% fiber weight fraction (FWF), or at least 60% by volume, or at least 70% by volume. In some exemplary embodiments, the unidirectional laminate has a fiber weight fraction of at least 72%, such as at least 73%, at least 74%, or at least 75% by volume.

[0120] In some exemplary embodiments, the present invention relates to discovering the correlation between the fatigue properties and tensile modulus of a unidirectional laminate and the viscoelastic properties of the composite material constituting the laminate. Therefore, by adjusting the viscoelastic properties of the composite material, the fatigue properties and tensile modulus of the resulting unidirectional laminate are optimized.

[0121] The specific viscoelastic properties discussed include the principal relaxation temperature (Tα) and storage modulus reduction (ΔE') of the composite material. These viscoelastic properties are controlled by the glass composition, glass fiber / matrix interface properties, resin type, and manufacturing method. High tensile modulus (at least about 45 MPa) and fatigue performance can be achieved in unidirectional laminates with a fiber volume fraction of at least 50 vol% by adjusting at least these viscoelastic properties within a specific range.

[0122] Specific viscoelastic properties of composite materials include adjusting the principal relaxation temperature (Tα) of the composite material to a range between about 110°C and 140°C, for example, between 112°C and 135°C, between 115°C and 130°C, between 115°C and 125°C, and between 117°C and 125°C. Optionally, the principal relaxation temperature (Tα) of the composite material may be in the range between about 115°C and 125°C. Additionally, the storage modulus reduction (ΔE') is adjusted to achieve a modulus between about 15 and 35 GPa, including between about 12 GPa and 30 GPa and between 20 and 25 GPa. Optionally, the storage modulus reduction (ΔE') of the composite material may be between about 20 and 25 GPa. By selecting materials that achieve the viscoelastic properties defined above, unidirectional laminates can be formed to have a tensile modulus of at least about 45 GPa and fatigue properties of at least 450 MPa at 1 mm cycles. In some exemplary embodiments, the unidirectional laminate formed by satisfying the viscoelastic properties described above has a tensile modulus of at least 47 GPa, including at least 50 GPa, at least 52 GPa, at least 55 GPa, at least 57 GPa, and at least 57 GPa. In some exemplary embodiments, the unidirectional laminate formed by satisfying the viscoelastic properties described above has fatigue performance of at least 460 MPa, or at least 475 MPa, or at least 480 MPa, or at least 500 MPa in 1 mm cycles. Example

[0123] The following paragraphs describe and illustrate exemplary embodiments of high fatigue and modulus unidirectional laminates. The exemplary embodiments are provided for illustrative purposes only and should not be construed as limiting the scope of this disclosure, as many variations are possible without departing from the spirit and scope of this disclosure.

[0124] Example 1

[0125] Figure 2 The relationship between the modulus of laminated parts and the fiber volume fraction of laminated parts is illustrated graphically, using both theoretical and experimental models. E is used in the following equations based on the law of mixing. H-玻璃 =82Gpa, E NGH-玻璃 =84 GPa, E 基体 =3.3 GPa to calculate the theoretical modulus:

[0126] E1 = E f V f +E m (1-V f )

[0127] Where E f E represents the modulus of the fiber. m Represents the modulus of the matrix and Vf This represents the volume fraction of the fiber.

[0128] like Figure 2 The study indicates that at FVFs between 50% and 57%, the laminated parts exhibit a 0° Young's modulus between approximately 45 GPa and 55 GPa, both in theoretical and experimental models.

[0129] Example 2

[0130] A unidirectional fiber-reinforced polyester laminate with a thickness of approximately 2 mm was obtained by vacuum impregnation of a continuously reinforcing material containing 17-micron diameter monofibers. The laminate was cured at room temperature for 24 hours and then post-cured at 80°C for 15 hours. The laminate was then vacuum impregnated with a resin system. The resin system was defined as a moderately reactive phthalic acid polyester resin with relatively high heat resistance and mechanical properties. Typical resin casting properties for this material are a tensile modulus of 3.3 GPa and an elongation at break between 3% and 4%.

[0131] Dynamic mechanical analysis (DMA) was performed on a 60 mm (l) × 10 mm (w) specimen using a 3-point bending mode. Temperature scan parameters included a frequency of 1 Hz and a temperature range of 2 °C / min. The amplitude was set to ensure the measurements were within the linear viscoelastic range. A typical DMA scan range for this type of laminate is 0 °C–200 °C. Tα (peak maximum) was determined on the tanδ curve.

[0132] High fatigue performance (at least 45 GPa after 1 mm cycles, according to ASTM E 739-91) is achieved by optimizing reinforcement through adjustments to the glass composition and / or resin chemistry, thereby affecting viscoelastic properties in the following range: T g Between 115℃ and 125℃, ΔE' is between 18 and 23 GPa.

[0133] exist Figure 3 The text explains the viscoelastic properties of such an adjustment. Figure 3 Describe the properties of DMA, and the ranges of Tα and ΔE'. Tα is the peak position on the tanδ curve. ΔE NORM is E' glassy–E' rubbery, normalized to 50% FVF. Figure 3 The text states that when ΔE'NORM is 18-25 GPa, Tα is in the range of 115-125 °C. Figure 3 In the text, “E” indicates the loss modulus: the loss response of the material.

[0134] Examples illustrate that low fatigue values ​​can be observed when one or a combination of the following factors are present: Tα greater than 125°C; FVF greater than 57%; and the use of an adhesive composition without epoxy film-forming agents and / or an adhesive composition without boron salts.

[0135] Unless otherwise specified or the context of reference clearly implies the opposite, all references to the singular feature or limitation of this disclosure shall include the corresponding plural feature or limitation, and vice versa.

[0136] All combinations of methods or process steps used herein may be performed in any order unless otherwise specified or the context of the combination clearly implies otherwise.

[0137] The composite materials, structural components, and corresponding manufacturing methods disclosed herein may include, consist of, or substantially consist of the essential elements and limitations of the disclosure as described herein, and any additional or optional components or limitations that may be used herein or otherwise in fiber-reinforced composite materials.

[0138] With regard to the use of the terms “include,” “includes,” or “including” in the specification or claims, they are intended to be inclusive in a manner similar to the term “comprising,” as interpreted when the term is used as a transition word in the claims. Furthermore, with regard to the use of the term “or” (e.g., A or B), it is intended to mean “A or B or both A and B.” The term “A or B only, and not both” will be used when the applicant intends to indicate “only A or B, and not both.” Therefore, the use of the term “or” herein is inclusive, not exclusive. In this disclosure, the words “an” or “a” should include both the singular and plural. Conversely, any reference to a plural term should include the singular, if appropriate.

[0139] In some embodiments, various inventive concepts may be combined with each other (e.g., one or more of the exemplary embodiments may be combined with each other). Furthermore, any particular element relating to a specific disclosed embodiment should be construed as applicable to all disclosed embodiments, unless the incorporation of a particular element contradicts the terminology used in the embodiment. Additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, this disclosure, in its broader aspects, is not limited to the specific details, representative devices, or illustrative examples shown and described herein.

Claims

1. A unidirectional laminated component, comprising: A fiber-reinforced composite material having a principal relaxation temperature (Tα) in the range of 110°C to 140°C, the fiber-reinforced composite material comprising a plurality of unidirectional reinforcing fibers coated with an adhesive composition and a matrix resin, wherein the unidirectional laminate has a tensile modulus of at least 45 GPa at a fiber volume fraction greater than or equal to 50% and fatigue mechanical properties of at least 450 MPa at 1 mm cycles, measured according to ASTM E 739-91, and wherein the fiber-reinforced composite material has a storage modulus reduction (ΔE') between 15 and 35 GPa, the storage modulus reduction (ΔE') being defined as E' glassy – E' rubbery, normalized to 50% fiber weight fraction.

2. The unidirectional laminate according to claim 1, wherein the reinforcing fiber is glass fiber, carbon fiber, or a mixture thereof.

3. The unidirectional laminate according to claim 2, wherein the reinforcing fiber is glass fiber.

4. The unidirectional laminate according to claim 3, wherein the glass fiber has an elastic modulus of at least 85 GPa.

5. The unidirectional laminate according to claim 3, wherein the glass fiber has an elastic modulus of at least 88 GPa.

6. The unidirectional laminate according to claim 3, wherein the glass fiber has an elastic modulus of at least 89 GPa.

7. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a tensile strength of at least 3500 MPa.

8. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a glass composition comprising 55% to 65% by weight SiO2.

9. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a glass composition comprising 17% to 27% by weight Al2O3.

10. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a glass composition comprising 8% to 15% MgO.

11. The unidirectional laminate according to claim 9, wherein the weight percentage ratio of Al2O3 to MgO in the glass composition is not greater than 2.

0.

12. The unidirectional laminate according to claim 10, wherein the weight percentage ratio of Al2O3 to MgO in the glass composition is not greater than 2.

0.

13. The unidirectional laminate according to claim 11 or 12, wherein the weight percentage ratio of Al2O3 to MgO in the glass composition is not greater than 1.

9.

14. The unidirectional laminate according to claim 11 or 12, wherein the weight percentage ratio of Al2O3 to MgO in the glass composition is not greater than 1.

8.

15. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a glass composition comprising 7% to 12% CaO.

16. The unidirectional laminate according to claim 10, wherein the weight percentage ratio of MgO to CaO in the glass composition is at least 1.

2.

17. The unidirectional laminate according to claim 15, wherein the weight percentage ratio of MgO to CaO in the glass composition is at least 1.

2.

18. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a glass composition comprising not more than 1% by weight of Na2O.

19. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a glass composition comprising no more than 2% by weight of TiO2.

20. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a glass composition comprising no more than 2% by weight of Fe2O3.

21. The unidirectional laminate according to any one of claims 3 to 6, wherein the glass fiber has a glass composition comprising not more than 0.5% by weight of Li2O.

22. The unidirectional laminated part according to any one of claims 1 to 6, wherein the adhesive composition comprises an epoxy film-forming agent, a silane package, one or more lubricants, and an antistatic agent.

23. The unidirectional laminated part according to claim 22, wherein the adhesive composition further comprises one or more thermoplastic film-forming agents.

24. The unidirectional laminate according to claim 23, wherein the thermoplastic film-forming agent is selected from one or more of the group consisting of: unsaturated polyester film-forming agents, functionalized epoxy polyvinyl acetate (PVAc) film-forming agents, and polyvinylpyrrolidone (PVP) film-forming agents.

25. The unidirectional laminated part according to claim 23 or claim 24, wherein the thermoplastic film-forming agent is present in the adhesive composition in an amount of 1 to 10% by weight solids.

26. The unidirectional laminate of claim 22, wherein the adhesive composition further comprises a boron-containing compound.

27. A wind turbine blade comprising a unidirectional laminated component according to any one of claims 1 to 26.

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