KR20150135378A - Improvements in or relating to fibre reinforced composites - Google Patents

Abstract

i) a first molding material, further comprising a layer of fibrous material and a curable resin over one side of the curable resin matrix, and further comprising a layer of fibers adhered to the fibrous reinforcement material;
ii) a second molding material comprising a fibrous material comprising two cross-linked fiber ply, wherein each ply comprises fiber tows oriented at different angles, and wherein the fibrous material further comprises a curable resin matrix A second molding material;
iii) a third molding material comprising together at least two stiffener layers having unidirectional fiber tows and a curable resin matrix bonding layer;
iv) a fourth molding material comprising a layer of fiber reinforcement and a curable liquid resin, wherein the fiber reinforcement comprises a plurality of tows, each tow comprising a plurality of filaments, the resin comprising a plurality of tows between tows of fiber reinforcement A fourth molding material, partially or wholly provided between the apertures, to provide a vent path in at least the interior of the tow; And
v) resin-impregnated fiber layer
A plurality of fiber-reinforced thermosetting resin layers selected from at least two of the thermosetting resin layers.

Description

[0001] IMPROVEMENTS IN OR RELATING TO FIBER REINFORCED COMPOSITES [0002]

The present invention relates to a fiber-reinforced composite material comprising a fiber-reinforced material and a resinous material, and more particularly, but not exclusively, to a composite-impregnated or pre-impregnated composite material or prepreg. The present invention relates to wind turbine blades and such materials that can be used to make wind turbine blades themselves, as well as parts for which such blades are made.

Typically, a portion of the composite is produced by a stacking layer of a fiber-reinforced material (also known as prepreg) that has been previously impregnated with a curable resinous material. Subsequently, the resin material is cured by heating the stack as it is being compressed. This causes the resin to flow while coagulating the fibrous stack and subsequently cured. This results in an integrated layered composite structure. The composite stratified structure is rigid and lightweight; Its uses are well known, and are often used in industrial applications such as automotive, aerospace and marine applications. Such structures are widely used in wind energy applications, such as wind turbine blades, particularly the hub of the outer shell of the blades, the inner spar, the root end of the spar and the turbine to which the blades are attached.

According to the present invention, structures, blades, parts, and molding materials as defined in any of the appended claims are provided.

In particular, the present invention relates to materials useful for manufacturing parts of wind turbine parts, in particular spares and shells of wind turbine blades and the use of such materials.

The wind turbine blade can be composed of two main pieces and the load bearing span extends along the interior of the blade having a root attached to the hub of the wind turbine and is generally tapered to the end of the blade or to the end of the blade, And is extended by a tapered method. The spas can be of any convenient shape, and the I beam is particularly useful. Spas are typically rectangular in cross-section and may include two halves attached rigidly to one another. The shell is mounted around the span to provide a surface exposed to the wind, and the shell is suitably constructed of an aerodynamic shape to obtain maximum interaction with the wind force. The shell is generally coupled to the spar and may also be in two halves joined together to provide a final blade. The vertical pillar on which the blades are mounted is provided with a hub in which each blade is attached by the root of the spar.

Both shells and spas in blades can be disassembled for assembly in the field. The sections can be made to fit well together. This allows the creation and movement of smaller sections for assembly of large blades in the field.

Wind turbine blades increase in size, especially in length, with the length of some blades now exceeding 50 meters, in some cases exceeding 70 meters. This increase in length requires greater strength when a thicker blade made from a larger stack of multiple composite fibers and resin stiffener layers is required, the thickness increasing the number of layers rather than increasing the thickness of the individual layers . However, as the number of layers increases, it becomes increasingly difficult to obtain the desired surface finish and homogeneity across the thickness of the blades and along the length of the blades. Typically, resin pre-impregnated fiber reinforcement (prepreg) is laid up in a mold to form this stack. Alternatively, the dry fiber layers are laid up in a mold, which is subsequently injected into a curable resin matrix using a vacuum assisted resin transfer molding process (VARTM).

Is known in the art to significantly reduce fiber warpage, linear distortion, wrinkling, or mechanical properties of the final composite structure, particularly strength and E-modulus, in fiber reinforced composite materials. Thus, the fabrication of composites bearing highly ordered fibers is highly desirable. In particular, in VARTM laying up with a dry fiber layer, maintaining fiber alignment during both lay-up and processing is a problem.

Various methods have been proposed for providing a prepreg molding material that can be used to make wind turbine blades. One process is an injection process in which the prepregs described above are produced by dry layup of reinforcing fibers, such as glass fibers, or carbon fibers. However, this is not a satisfactory technique for use over the entire width of a shell or spar of an extended length wind turbine blade. Alternatively, a prepreg that can be wet or dried in the cured laminate can be inserted, and the stack is cured to produce the final blades. Another proposed technique is to lay up the permeable nonwoven fabric with the prepreg so that air can be removed from the system during and during the lay-up. The nonwoven fabric may be in the form of a fleece. Preferably, the fleece has a weight in the range of 20 to 100 gsm, preferably 40 to 60 gsm. Here, the use of such a single material over the width of the shell or spar was also unsatisfactory. As the length of the wind turbine blades increases, the inventors have found that no material is optimal for the production of the entire blades, whatever the fabrication process.

The present inventors have found that a shell having an improved surface aerodynamic finish and a component having improved homogeneity and reduced cavitation can be achieved by using different prepreg materials over the length of a wind turbine component such as a shell, .

Accordingly, the present invention relates to various materials that can be used in various parts of blades, including spas, shells and hubs. Additionally, the present invention relates to spas, shells and hubs made from two or more of such materials. In addition, the present invention provides a collection of parts produced from such materials, which can be assembled to produce a shell, perhaps in two parts, a spar in two parts, and a blade optionally comprising a hub.

Accordingly, the present invention provides the following materials suitable for use in making springs and shells of wind turbine blades, particularly wind turbine blades.

1st  Molding material

In a first embodiment, the present invention provides a first molding material comprising at least one layer of a curable resin layer and a layer of fibrous material on at least one side of a curable resin matrix, wherein the molding material is further adhered to the fiber- And a further fiber layer.

In a preferred embodiment, the fiber reinforcement is impregnated from one side of the material and the additional fiber layer is bonded to the opposite side of the fiber reinforcing material. The use of additional fiber layers comprising a nonwoven fibrous material having an area weight in the range of 5 to 50 g / m ² , preferably 5 to 20 g / m ² (gsm) is particularly suitable.

The nonwoven material may preferably be in the form of a wide-mesh scrim or web, which may be made of any suitable material, but is preferably a thermoplastic yarn. An important requirement of the actual material is that it has a melting point similar to or higher than the prepreg gelling temperature so that the scrim is not melted during the curing process. Preferably, the difference between the actual melting point and the matrix gelation point should be at least 10 ° C. Suitable materials for the scrim include polyester (76-1100 dtex) such as polyethylene terephthalate and polybutylene terephthalate and copolymers thereof, polyamides (110-700 dtex) such as nylon 6, nylon 66, nylon 11 and nylon 12, polyethersulfone, polypropylene, viscose yarns (143-1000 dtex), meta and para-amides (Kevlar 29 220-1100 dtex) and Nomex T-430 (220-1300 dtex) -1360 dtex, jute (2000 dtex), flax (250-500 dtex), cotton (200-500 dtex), and combinations of one or more of these. Such materials are available from Bellingroth GmbH under the trade name Bafatex.

Further, the fiber-reinforced material comprises a fiber tow comprising filaments having an average diameter in the range of 1 to 20 μm, preferably 10 to 15 μm, and comprises 15 to 70% by volume of tow, 18 to 68% From 25 to 55% by volume of toe, from 25 to 45% by volume of toe, from 25 to 40% by volume of toe, from 25 to 60% by volume of toe, from 25 to 60% The fiber volume fraction of the tow ranges from 35 to 35 vol%, 25 to 30 vol% toe, 30 to 55 vol% toe, 35 to 50 vol% tow and / FVF).

Second  Molding material

In a second embodiment, the present invention provides a second molding material comprising a fibrous material comprising two cross-linked fiber ply, wherein each ply has a fiber tow oriented at different angles, And a second moldable material comprising a further curable matrix. An example of such a suitable material is the product available from Hexcel HexPly M 9.6 GF / 38% / BB 600, a biaxially oriented glass fiber BB600 impregnated with 38 wt% epoxy resin M 9.6 GF.

In a preferred embodiment, the ply is electrically conductive by being typically contained in a ply of carbon fibers, and such ply is sacrificed when striking by lightning.

Third  Molding material

A third embodiment of the present invention comprises a third molding material comprising two or more reinforcing layers having a unidirectional fiber tow and a curable resin matrix bonding layer together. An example of such a suitable material is a product available from Hexcel as Hexfit. Such material contains 34 wt% epoxy resin.

Fourth  Molding material

In a fourth embodiment, there is provided a fourth molding material or structure comprising a fiber reinforcement layer and a curable liquid resin, wherein the fiber reinforcement comprises a plurality of tows, each tow comprising a plurality of filaments, Is at least partially provided between the gaps between the tows of the fibrous reinforcement material to provide a vented air path at least within the tow. The interior of the tow does not at least partially contain resin to provide a vent hole path to remove air during processing of the material or structure.

Fifth  Molding material

In a fifth embodiment, there is provided a fifth molding material comprising a unidirectionally pressure-cured laminate, such as the product obtainable from Hexcel, designated PolySpeed (R). A preferred cured laminate can be Polyspeed (R) GR 120, a pressure-cured laminate containing an average weight of unidirectional fibers of about 1200 g / m ² , in particular containing 2400 tex glass fibers and containing 25 to 30 wt% epoxy resin.

The cured laminate may include one or more chamfered ends.

In a further embodiment, as a fifth molding material in the unidirectional laminate form, a fifth molding comprising a unidirectional fiber and a dry fiber region in the resin matrix in which the laminate is cured, preferably a dry fiber region in the longitudinal or warp direction Material is provided. The laminate may include a partially impregnated region in the warp direction. The present inventors have found that such dried or impregnated areas improve the drapability of the laminate in the mold of a composite shape. They also improve the venting of any entrapped gas during processing and curing, which improves the bond between the laminate and the materials surrounding it in lay-up. The laminate may be a press-hardened or pultruded laminate.

In a further embodiment, as a fifth molding material in the unidirectional laminate form, there is provided a fifth molding material comprising unidirectional fibers in the resin matrix in which the laminate is cured and longitudinal gaps extending in the longitudinal or warp direction. The inventors have found that such a gap improves the drape of the laminate in a mold of a composite shape. The laminate may be a press-hardened or drawn laminate.

In another embodiment, there is provided a fifth molding material in the form of a multi-cured laminate layer joined together by a dry stiffener and / or stitching and / or prepreg material. The cured laminate layer may be in the form of a laminate comprising a unidirectional fiber and a dry fiber region in the cured resin matrix, preferably a dry fiber region in the longitudinal or warp direction. The laminate may include a partially impregnated region in the warp direction. The laminate comprises unidirectional fibers and a dry fiber region in the cured resin matrix, preferably a dry fiber region in the longitudinal or warp direction. The laminate may include a partially impregnated region in the warp direction. The laminate may also include unidirectional fibers in the cured resin matrix and longitudinal gaps extending in the longitudinal or warp direction. The laminate may be a press-hardened or drawn laminate.

In yet another embodiment, there is provided a fifth molding material in the form of a unidirectional laminate, wherein the laminate comprises a fabric on one or both sides of a fibrous reinforcement and a carbon fiber in the form of unidirectional carbon fibers, the fabric is stitched thereto, A fifth molding material is provided in which the fiber reinforcement is impregnated with fiber and cured. The fabric may include fibers in the warp direction and fibers in the weft direction and the weft direction is an angle of 90 or 30 to 85, preferably 60 to 80. The fabric may be nonwoven. The fabric may comprise glass fibers.

In a further embodiment, a fifth molding material comprising a cured resin-impregnated fibrous reinforcement layer to which a further stiffener layer is bonded, wherein said additional stiffener layer is a dry (non-impregnated) fibrous reinforcement material and / And a fifth fiber-reinforced stiffener layer is provided. An additional stiffener layer may extend past the cured resin-impregnated fiber stiffener layer.

With regard to embodiments of the fifth molding material mentioned above, the inventors have found that such dry or impregnated areas improve the drift of the laminate in the mold of a composite shape. They also improve the venting of any trapped gas during processing and curing and improve the bond between the laminate and the materials surrounding it in lay-up.

The present inventors have discovered the further advantage of the present invention that surface defects can be reduced or eliminated by the inclusion of one or more fifth layers of molding material. This reduces the overall cure time by reducing the emission of exothermic heat during cure of the layup, since it allows the layup to cure at a higher temperature compared to the layup where the cured layer is replaced by an equivalent uncured layer .

In a sixth embodiment, the material is a conventional fiber-reinforced prepreg, such as carbon or glass fiber, surrounded by a thermosetting material, particularly a matrix of epoxy resin.

Accordingly, the present invention relates to the use of a combination of two or more of these materials in the manufacture of components used in wind turbine blades, such as shells, spas and hubs of blades. The material can be combined or incorporated in the lay-up of the dry reinforcement that is subsequently injected with injection resin, such as Prime 20, supplied by Gurit.

The choice of the combination of materials to be used in the production of the parts of the wind turbine blade is determined by the desired properties, and in general the cost of the glass fiber reinforcement is lower than that of the carbon fiber reinforcement. On the other hand, carbon fibers provide increased strength at reduced weight. However, the inventors have found that including one or more layers of the product according to the first embodiment in a stack comprising a plurality of carbon fiber-based prepreg layers, such as the product according to the third embodiment, produces a larger uniform surface finish And also results in a more uniform, less porous structure containing less voids during curing and increases strength. In addition, the inventors have found that one or more layers of the product of the fifth embodiment, such as PolySpeed (R) GR 120, may be deposited on a stack of multiple layers of product UD 600, optionally comprising one or more layers of the product of the third embodiment such as HexFIT Has also been found to improve surface finish, reduce porosity and cavities, and improve the strength of wind turbine blade components.

In a preferred embodiment, layers of products such as HextFit 2000 and PolySpeed GR 120 are provided at substantially regular intervals throughout the stack of prepregs. An intermediate layer constituting 10% to 30%, preferably 15% to 25% of the total number of layers is particularly suitable.

In some cases, it may be necessary to include additional materials in the components of the present invention. For example, horizontal wires or carbon tows may be needed to increase the electrical conductivity.

In another embodiment of the present invention, the molding material or structure also contains a tow of a fiber reinforcement to provide a vent hole path. Tow is actually a structural or reinforcing fiber, because it acts on multiple purposes, providing a venting path on one side and structural reinforcement on the other. In these materials, the apertured resin ensures that the material has a sufficient structure to allow handling of the material at room temperature. This is achieved because the resin at room temperature (23 DEG C) has a relatively high viscosity, typically in the range of 1000 to 100,000 Pa.s, more typically in the range of 5000 Pa.s to 500,000 Pa.s.

In addition, the resin may be tacky. Tackiness is a measure of the adhesion of a prepreg to a tool surface in an assembly or to another prepreg ply. Adhesion can be measured on the resin itself or on the prepreg according to the method described in "Experimental analysis of prepreg tack", Dubois et al, (LaMI) UBP / IFMA, 5 March 2009. The document is based on the use of the equipment described in the document and for a probe which comes into contact with a resin or prepreg at a starting temperature of 30 N at a constant temperature of 30 캜 and then moves at a rate of 5 mm / Describes that the stickiness can be measured objectively and repeatedly by measuring the maximum dislocation force. For these probe contact parameters, the stickiness F / _Fref for the resin is in the range of 0.1 to 0.6, where _Fref = 28.19N and F is the maximum release force. In the case of the prepreg, the sticky F / F _ref is in the range of 0.1 to 0.45 for F / F _ref , where F _ref = 28.19 N and F is the maximum release force. However, a fiber support web, grid, or scrim may also be disposed on at least one outer surface of the fiber reinforcement to further enhance the integrity of the material or structure during storage and processing.

In further embodiments, the materials and structures may also include non-impregnated tows and / or at least partially impregnated tows. Preferably, the reinforcement comprises non-impregnated tow ("dry tow") and fully impregnated tow. The layer of fibrous reinforcement comprises at least partially hollow embedding voids in at least partially impregnated fibrous reinforcement. The partially impregnated fiber reinforcement may be a unidirectional reinforcement or a woven fiber reinforcement or a nonwoven fibrous reinforcement.

One or more of the two or more distinct fibrous reinforcement layers may be impregnated with a resin and the other layer may be unimpregnated or substantially unimpregnated and the layer is bonded such that the resin is present between the crevices of the tow. Preferably, the layer is bonded such that at least partially embedded between the non-impregnated or substantially non-imbibed tow-impregnated tows. The layer comprises a unidirectional tow, the tow of each layer being substantially parallel. The two layers can be joined by compression so that the unidirectional tows are all in the same plane or in substantially the same plane. One or more additional fibrous layers may also be combined with the bonded layers.

The weir material may be present on the surface of the resin impregnated fiber reinforcement. The weave material can be fixed in place by the tackiness of the resin. The weaving material is then adjusted accordingly.

In a further aspect, the impregnated and non-impregnated tow may be co-located to form a single plane of fibrous reinforcement. The longitudinal axes of the impregnated and non-impregnated tows in a layer or sheet of fibrous reinforcement may be parallel to each other and their axes may all be located in a single plane.

In a further embodiment, the material or structure may comprise a combined impregnated and non-impregnated tow layer, wherein the longitudinal axes of the impregnated and non-impregnated tow are located in the same plane.

The inventors have found that a blade having improved surface finish, strength and homogeneity can be obtained when two or more of the various materials of the present invention are optionally used with other materials described herein to form various components of a wind turbine blade . Accordingly, the present invention also provides a section of a wind turbine blade or parts thereof made from two or more materials of the present invention. Accordingly, in a further embodiment, the present invention provides a wind turbine blade or a part thereof, comprising a first section and a second section over the width of the part, said sections comprising different molding materials of the present invention.

The second section of the blade preferably comprises a molding material that can comprise a material comprising a stiffener layer having a unidirectional fiber tow and a curable resin matrix for impregnating the stiffener layer from one side. The stiffener layer may include a penetrable thermoplastic layer on the opposite side to which this layer is impregnated, and in this manner, air may be removed during lay-up and curing to reduce cavitation of the part.

In yet another further embodiment, the wind turbine blade or part comprising the first and second sections may contain additional sections that may include additional molding material of the present invention.

The present invention further provides kits of parts for making wind turbine blades or parts thereof comprising any molding material of the present invention. The kit may include various shorter sections that can be assembled in situ with the final blades.

The resin material used for all the materials of the present invention is a thermosetting resin such as an epoxy resin or a polyurethane resin, and an epoxy resin is preferable. The choice of resin material will depend on the application and use of the laminate. The resin in all materials is preferably an epoxy resin, and in each of the materials used to produce a single part, the resin must be cured under the same curing conditions. In addition, the reinforcing material present in the material can be selected from a variety of suitable fibers, often including carbon, aramid, basalt or glass fibers. The fibrous material may be provided in a woven or nonwoven form. In a preferred system of the present invention, different sections may contain different fiber reinforcements over the thickness of the part and may vary depending on the nature of the fibers, the orientation of the fibers, and whether the fiber layers are woven or nonwoven.

Woven fabrics can be used in the present invention, which generally contain both longitudinal warp tows of the fabric and transverse weft fiber tows of the fabric. The tow consists of multiple fiber elements called filaments that together form a tow. The warp tow and the weft tow may contain the same material and may be of the same weight or may contain different materials and / or weights. The warp and weft tow can be arranged at an angle that can range from +/- 10 DEG to +/- 90 DEG with respect to each other. Some wovens contain a relatively small number of warp tows. This provides a fabric with sufficient stability such that the weft tufts are deflected in the longitudinal direction. This is accomplished by applying tension on one side of the fabric while maintaining the fabric on the opposite side. This is disclosed, for example, in EP 1880819. Typically, this nature of fabric has 70-90% of weft fibers and 30-10% of stabilizing warp fibers. A deflected fabric has the drawback that the presence of a weft fiber tow introduces a crimp into a warp fiber tow. As a result, this affects the mechanical performance of the composite part produced from this material. Moreover, the woven fibers result in small deviations on the other flat surface of the fabric, which acts as a position for trapping air when the resin is applied to form a prepreg, and then the collected air is transferred to the final laminate Thereby further reducing the mechanical properties.

The range of nonwoven fabrics ranges from fabrics containing random fiber elements, such as truncated strand fabrics, to fabrics containing regular to parallel tows. Within this application, the latter is referred to as the "oriented reinforcing fabric" preferred for the material of the present invention.

An important advantage of the reinforcing fabric oriented opposite to the above-mentioned woven fabric is that the fiber tow is not affected by the crimp and, accordingly, the resulting composite structure has improved mechanical performance.

In some aspects of the invention, the material used may be a partially or fully cured fiber-reinforced sheet material, such as the PolySpeed (R) GR 120 described above, which enables a very high fiber content and highly oriented fibers in the sheet . Moreover, the fact that the sheet is cured facilitates sheet movement since no specific conditions such as temperature range or humidity range are required. Also, the combination of the sheet shape and the cured state facilitates the alignment of the fibers in the lay-up forming the composite member or part, or in other words, the adjustment of the sheet to the shape of the mold without inhibiting the linearity. This is particularly important for complex shapes such as airfoils (shells) of wind turbine blades where the desired fiber distribution has a complex three-dimensional shape.

The element of the desired shape may be cut from the sheet material to facilitate forming the composite member or part in a particular lay-up.

In making parts of a wind turbine blade, at least a portion of the elements of the cured fiber-reinforced sheet material may be positioned in a ply that partially overlaps to provide a plurality of substantially parallel element edges. This makes it possible to place the element very close to the surface of the mold and almost any desired overall distribution of the reinforcing fibers can be realized by adjusting the overlapping area between the elements. In particular, the element can be located in the cross-section of the shell of the wind turbine blade so that the fiber is substantially similar to the distribution of water in the rake having a depth profile corresponding to the distance from the centerline of the blade to the surface of the cross-section. In a particularly preferred embodiment, the substantially parallel element edge is an edge substantially parallel to the length of the element of the cured fiber-reinforced sheet material. This results in a relatively short resin introduction length, thereby making it easier to make and reproducible. The cured fiber-reinforced sheet material may be located in the vicinity of the outer surface of the blade as a partially overlapped tile. The cured fiber-reinforced sheet material is a cured fiber-reinforced sheet material that is drawn or band pressed and is divided into elements of the cured fiber-reinforced sheet material.

The cured element may include one or more chamfered ends to facilitate joining of the elements.

In yet another embodiment, the wind turbine blade according to the present invention has a length of at least 40 m. The ratio t / C of the thickness t to the cord C is generally substantially constant in the range of 75% < r / R < 95% in the case of the airfoil section, And R is the total length of the blade. Preferably, the thickness ratio for a given cord is realized in the range of 70% <r / R <95%, more preferably 66% <r / R <95%. This can be realized in the case of wind turbine blades according to the invention due to the very tight packing of the fibers in the region of the cross section of the blades providing a high moment of inertia. It is therefore possible in accordance with the invention to achieve the same moment of inertia with fewer reinforcing materials and / or achieve the same moment of inertia with a larger slim profile. This is desirable because it saves material and enables airfoil design according to aerodynamic requirements rather than according to structural requirements.

The cured molding material constituting the turbine blade or parts thereof comprises from 45 vol% to 75 vol% (fiber volume fraction), preferably from 55 vol% to 70 vol%, more preferably from 58 vol% to 65 vol% EN 2564 A). &Lt; / RTI &gt; The molding material may comprise from 10% to 60%, preferably from 20% to 50%, more preferably from 30% to 40%, most preferably 35% by weight of the resin of the molding material have.

The molding material may be formed of a fiber-reinforced material having a total area weight of substantially 600 gsm. The fiber reinforcement may comprise two fabric layers having tows arranged at substantially + 30 ° or -30 ° or + 45 ° or -45 ° in each layer. The individual fabric layers may each have an area weight of substantially 300 gsm. The individual fabric layers may comprise a support layer of an area weight of 10 gsm. Such a fabric may be combined with a resin, examples of which may be the M9.6 resin supplied by Hexcel. The resin may be combined with a fiber reinforcement, for example, at 35% by weight of the molding material.

The elements of the cured fiber-reinforced sheet material can be provided along the length of a shorter or longer fraction of the shell of the blades. However, typically, the element is preferably located along a length of at least 75% of the wind turbine blade shell member, and in many cases, the cured fiber-reinforced sheet material is at least 90% It is more preferable to be positioned.

The material of the present invention is generally at least ten times the width and relatively flat, and the width is at least five times the thickness of the sheet material. Typically, the length is at least 20-50 times the width and the width is at least 20-100 times the thickness. In a preferred embodiment, the shape of the sheet material is band-like.

The fiber-reinforced sheet material is preferably dimensioned so that they can be rolled. Being rolled up means that the sheet material can be wound onto a roll having a diameter that allows movement in a standard sized container. This greatly reduces the cost of fabricating the composite member since an infinite coil of cured fiber-reinforced sheet material can be manufactured in a central facility and carried to a blade making location, which can be divided into elements of appropriate size to be. In order to further improve transport, the thickness of the fiber-reinforced sheet material is preferably on the roll to a diameter of less than 2 m based on the flexibility, stiffness, fiber type and fiber content of the cured fiber- And the like. Typically this corresponds to a thickness of up to 3.0 mm, but in the case of high fiber content and stiffness, a thickness of less than 2.5 mm is generally more suitable. On the other hand, thick sheet materials enable rather large steps in the outer surface where thinner sheet materials are preferred. However, the sheet material should typically be thinner than 0.5 mm, since a large number of sheets are needed thereafter resulting in increased fabrication time. In a preferred embodiment, the thickness of the cured fiber-reinforced sheet material is about 1.5 to 2 mm.

The cured fiber-reinforced sheet material that can be used as the layer of the composite can have the following properties (referring to the measurement standard):

The fiber volume fraction is the volume of sheet material occupied by the fibers. The sheet may have an area weight of 2000 to 4000 g / m ² , preferably in the range of 2200 to 2800 g / m ² , more preferably of 1500 g / m ² . The Tg of the resin matrix may be 100 to 150 캜, preferably 110 to 140 캜, more preferably 110 to 130 캜.

If a cured fiber reinforced layer is used, the surface of the layer may be modified, such as by sandblasting, and the surface texture may additionally or alternatively be channeled to the major surface of the cured fiber- And preferably the recess is approximately 0.1 mm to 0.5 mm below the major surface, but in some cases a larger recess may be suitable. Typically, the protruding and / or recessed portions are separated by 1 cm to 2 cm and / or 0.5 to 4 cm, but the gaps may be larger or smaller depending on the actual size of the corresponding protruding and / It can be narrow.

The surface texture of the type described above may be provided, for example, after fabrication of the fiber-reinforced sheet material cured by sandblasting, grinding or dripping of a semi-solid resin on the surface, It is preferred that a surface texture that facilitates the introduction of resin between adjacent elements of the fiber-reinforced sheet material is provided during fabrication of the cured fiber-reinforced sheet material. This is particularly easy, especially when the cured fiber-reinforced sheet material is produced by belt pressing because the surface texture can be induced through a negative template or the surface texture can be transferred to the belt of the belt press As shown in FIG. In another embodiment, a foil is provided between the belts, and fiber-reinforced sheet material is formed in the belt press. Such a foil may also act as a liner, which must be removed prior to introduction of the fiber-reinforced sheet material cured in the mold.

It may be necessary to introduce the resin into the stack of material layers of the invention before curing. The introduction of the resin can advantageously be assisted by a vacuum. This involves forming a vacuum enclosure around the composite structure. The vacuum enclosure may be formed by providing a flexible second mold portion in a vacuum, which is preferably in intimate communication with the mold. The vacuum can then be provided to the vacuum enclosure by a vacuum means, such as a pump, in which the vacuum communicates with the vacuum enclosure such that the resin can be introduced by a vacuum assisted process, e.g., a vacuum assisted resin transfer molding, i.e., VARTM . Vacuum assisted processes are particularly suitable for large structures, such as wind turbine blade shells and spar members, because long resin transport distances can otherwise lead to premature curing of the resin and this can prevent further injection of resin to be. Moreover, the vacuum assisted process will reduce the amount of air in the wind turbine blade shell member and thereby reduce the presence of air in the injected composite, which increases homogeneity and strength as well as reproducibility.

The injection resin may be curable by external application at a temperature of 60 to 100 占 폚, preferably 60 to 90 占 폚, more preferably 80 to 100 占 폚. The temperature during curing will be higher due to the exothermic nature of the curing reaction. The resin may have a viscosity during the injection step of 50 to 200 mPas, preferably 100 to 160 mPas, more preferably 120 to 150 mPas. The pure injection resin has a density in the range of 1.1 to 1.20 g / cm &lt; ³ &gt;; A flexural strength of 60 to 150 N / mm ² , preferably 90 to 140 N / mm ² ; Modulus of elasticity of 2.5 to 3.3 kN / mm ^2, preferably from 2.8 to 3.2 kN / mm ^2; A tensile strength of 60 to 80 N / mm ² , preferably 70 to 80 N / mm ² ; A compressive strength of 50 to 100 N / mm ² ; An elongation at break of from 4 to 20%, preferably from 8 to 16%, and / or a combination of the above-mentioned characteristics.

A suitable injection resin may be Epikote MGS RIM 135 supplied by Hexion or Prime 20 supplied by Gurit.

As discussed, the implantation layup may be combined with any one of the molding materials as described herein, alone or in combination.

Any inner surface layer material may be provided on the elements of the cured fiber-reinforced sheet material. While any inner layer material may also be provided after the introduction of the resin between the elements, the presence of the inner layer material is not essential to the wind turbine blade shell member. The outer layer material as well as the inner layer material may comprise fibers and the fibers are oriented differently from the fibers of the elements of the cured fiber-reinforced sheet material so that the lateral strength of the wind turbine blade shell member .

One of the main advantages of using an element comprising a layer of cured fiber-reinforced sheet material is that the reinforcing material can be placed very freely in the design. Generally, it is desirable that the reinforcing material is located far from the center of the structure to enable high momentum of the stiffener. When done with a superimposed layer or element, this can be accomplished by a plurality of elements having substantially the same shape, or by a plurality of elements having only a few different shapes in situations where a complex geometric total stiffener structure is desired . This is possible by varying the angle and degree of overlap between the outer surface of the composite surface and the elements of the cured fiber-reinforced sheet material.

Accurate positioning of the elements of the fiber-reinforced sheet material in the mold can be facilitated by the use of template means showing the desired position. This is especially the case when a more complex system of elements is desired or when passive layup is used. The template means represents the relative position of the elements of the cured fiber-reinforced sheet material with respect to the end corresponding to the end of the wind turbine blade shell member and / or the at least one member relative to the mold, e.g. the mold edge or mold feature, For example, the relative position of the hole or tab. The indication of the correct position may include a longitudinal position, a widthwise position and / or a heightwise position relative to the mold and / or to the further element of the cured fiber-reinforced sheet material or other element to be included in the composite structure.

The template means may be integrated into the wind turbine blade shell member to be a disposable template. In a preferred embodiment, the template means can be integrated with the core element of the composite structure.

In the case of a large element, such as a wind turbine blade, where the cured fiber-reinforced sheet material can typically be approximately the entire length of a wind turbine blade, several template means may be used, for example one at each end, It may be advantageous to apply one, two, three or more on the selected location along the path.

The elements of the fiber-reinforced sheet material are joined together by the resin as discussed above, but it is also possible to add elements of the fiber-reinforced sheet material during the lay-up to another element, such as one or more of the other It is very advantageous to immobilize the material at least temporarily. Temporary fixation should be such that fixation does not result in unacceptable bonding during use of the final product or during subsequent introduction of the resin. Fixing may be accomplished, for example, by one or more adhesives, such as a hard-meltable or non-curable hot-melt resin or a double-coated tape; Or mechanical fastening means, for example, a wire or an elastic member having clamps, wires, loops. In a particularly preferred embodiment, the means for temporary fixation is not removed prior to the introduction of the resin, and is thus included in the finished composite structure. In such a case, it is particularly important that the means for temporary fixation be compatible with the elements of the final structure in both a chemical view (e.g. for the resin) and a mechanical viewpoint (e.g. no mechanical spot formation) .

In a preferred embodiment, the plurality of elements of the cured fiber-reinforced sheet material comprises two or more types and / or sizes of fibers. The fibers are preferably selected from the group consisting of carbon fibers, glass fibers, aramid fibers and natural fibers such as cellulose-based fibers, preferably wood fibers.

The fibers may be arranged such that at least one of the elements comprises a combination of two or more types of fibers, such as carbon fibers and wood fibers or carbon fibers and glass fibers. In a particularly preferred embodiment, the plurality of elements comprise a first element group having a first fiber composition and a second element group having a second composition. Preferably, the first fiber composition is composed substantially of carbon fibers such that the first group of elements is particularly rigid with respect to the weight and volume of the cured fiber-reinforced sheet material. The second fiber composition may comprise another carbon fiber or another fiber, for example glass fiber.

A support structure may be provided to support the arrangement of unidirectional tows in the material of the present invention so that the orientation is maintained. The support structure may be of a different type, such as a binder, a thread in the form of a stencil, or a loop or cord of fibers that join the tow, a cured, partially cured, uncured cured resin matrix, and / Lt; / RTI &gt; The support structure is adapted so that it does not contain any fibers that are woven in the fabric without significantly interfering with the arrangement of the fiber tow, and therefore, does not introduce any clamps in the fabric. This allows the surface of the fabric to be formed with a smoother surface profile, thereby reducing the air (air in the layer) that is trapped in or inside the fabric when the resin is applied.

In one embodiment, the support structure may include support structure fibers applied in the form of loops passing around the tow. The loops can be arranged so that the support structure fibers extend from one side of the fiber reinforcement layer to the opposite side so that the tows are rounded to join the tows together. Support structure fibers can be passed between adjacent tows, so that they can also introduce a gap between the tows. This arrangement provides support for the fabric as well as providing air vent paths in the interlaminar and in-layer directions. The gap also facilitates complete wetting during the curing step, which is particularly important for applications requiring the use of heavy fabrics or high fiber densities.

The support structure fibers preferably include continuous fibers that are applied to the fabric in a repeating stitch pattern, but may also include discontinuous fibers. The supporting structure fibers combine the tows of the fabric and the repeating loops, which are preferably applied in a linear pattern, and the linear loops can be applied in any direction but in the 0 DEG direction. Additional support structure fibers may be applied to the opposite side of the fabric so that they pass through a loop fabricated from fibers originating from the first side of the fabric.

The unidirectional alignment of the fiber reinforcement is aligned substantially at an angle of more than 0 [deg.] In the longitudinal direction. Typically, the support structure is applied to the fiber reinforcement parallel to the longitudinal length, but it can be applied at any angle to the longitudinal direction. The support structure and the non-parallel arrangement in the fiber direction provide greater stability to the fiber reinforcement. However, it should be noted that the fiber direction can be parallel to the longitudinal direction and the support structure can be applied in a non-parallel manner thereto. Alternatively, the support structure may be applied parallel to the fiber direction, but it may reduce support to the fiber reinforcement.

The support structure may comprise a resin, wherein the resin provides support for the fiber reinforcement. The use of a resin as a support structure can eliminate or reduce the amount of support structure fibers needed for the stability of the fabric.

The support structure of the resin may be applied to the fabric in a resin layer which may be continuous. The resin supporting structure can be applied to one or both sides of the fiber reinforcing layer.

The support structure may comprise a resin applied to a separate element, and preferably comprises a cured or partially cured resin. The separate elements of the resin can be applied, for example, in the form of a strip, globule or random line pattern. Such an element may be applied on one or both sides of the fiber reinforcement layer. Both the uncured resin and the cured resin may be used to provide sufficient stability to the handling of the fiber reinforcement layer. The space between the resin elements can act as a channel to provide a vent path for air removal during lay-up. The resin support structure also provides spacing between adjacent fiber layers for improved ventilation. The resin support structure may comprise a hardenable resin and a resin support layer of this nature may be applied to the fiber reinforcement layer and may be immediately cured or may remain uncured until cured as part of the lay- have. The resin support structure may include a thermoplastic material that is melted, applied to the fiber reinforcement layer, and frozen.

The support structure may also include scrims arranged on one or both sides of the fiber stiffener layer. The scrim may enter the gap between the tows in the fiber reinforcement. In addition to supporting the fibrous reinforcement layer, the scrim can also improve the aeration by providing a path for removing gas during curing. The scrim may include a veil. The veil may comprise a lightweight fabric having a weight in the range of 3 to 30 gsm (g / m ² ), preferably 5 to 15 gsm.

The bail may be attached to the fiber reinforcement. The bail includes a thermoplastic material and can provide toughness on the laminate as well as support for the fiber reinforcement layer. The support structure may be bonded to the fiber reinforcement layer by melt bonding, stitching, adhesive, or tackiness from a cured or uncured resin.

The support structure may comprise a fiber support layer. The fibrous support layer may be a layer on which a fibrous reinforcement layer is adhered. The support layer may be melt bonded, stitched, adhesively bonded, or attached by any bonding method known in the art, including utilizing the tackiness of the resin. The backing layer imparts stability to the fiber reinforcement and improves handling characteristics. The support layer can also improve the venting of the molding material. The fibrous support layer can be attached to the fabric by supporting fibers that can pass through the entire thickness of the support layer. The backing layer may comprise a fiber mat, woven or unidirectional fibers. In one embodiment wherein the backing layer comprises a fiber mat, it preferably comprises fibers having a weight range of 3 to 30 gsm, preferably 5 to 15 gsm, more preferably 2 to 13 gsm. Preferably, the fibers are formed from glass, carbon or polymer, which may be formed from jute, flax, basalt or any other fiber known in the art.

One of the molding materials of the present invention comprises a nonwoven fibrous reinforcement layer having fiber tow in a single layer oriented at a selected angle (typically 30 or 45 relative to the warp). Nonwoven fiber reinforcements do not have a crimp because they are non-woven. This improves the mechanical performance of the laminate, which can be formed from such materials. The fibrous tow of the nonwoven fibrous reinforcement layer is held in place by the support structure in the form of cross-stitching. Cross-stitching facilitates the release of the collected gas during processing and curing of the molding material. This is particularly advantageous for vacuum assisted molding techniques outside the autoclave.

In certain materials, the fibrous material is impregnated with a resinous material. The viscosity of the resin and the method used for impregnation are chosen to achieve the desired impregnation. Impregnation can be assessed using a water pickup test. In order to increase the rate of impregnation, the process may be carried out at elevated temperatures such that the viscosity of the resin is reduced. However, it should be too hot for too long to accelerate the hardening of the resin. The relative amount of resin to the reinforcing material, impregnation line speed, viscosity of the resin and density of the multi-filament tow can be adjusted to achieve the desired degree of impregnation between the tows and to provide a tow that is not occupied by the resin Lt; RTI ID = 0.0 &gt; filaments &lt; / RTI &gt; Thus, the impregnation process is preferably carried out at a temperature in the range of 40 占 폚 to 110 占 폚, more preferably 60 占 폚 to 80 占 폚. The resin of the prepreg is preferably such that the cured molding material after curing contains 30 to 40 wt%, preferably 31 to 37 wt%, more preferably 32 to 35 wt% of the resin.

The resin diffuses on the outer surface of the roller and can be coated on paper or other backing material to create a curable resin layer. Thereafter, the resin composition may be contacted with the multi-filament tow by passing it through the roller, perhaps for impregnation. The resin can be on one or two sheets of backing material, which is brought into contact with one or both sides of the tow and is solidified, such as by passing it through a heated solidification roller, resulting in the desired impregnation. Alternatively, the resin can be applied by treating the tow with a resin through a resin bath (direct fiber impregnation). The resin may also include a solvent that has evaporated after impregnation of the fiber tow.

In a further embodiment, the resin during impregnation may be a resin that is liquid at ambient temperature, or may remain in liquid form in a molten resin bath if it is a solid or semi-solid resin at ambient temperature. The liquid resin may then be applied to the backing using a doctor blade to produce a resin film on a release layer, such as paper or a polyethylene film. The fibrous tow can then be disposed in the resin and optionally the second resin layer is provided at the top of the fiber tow and then solidified or the backing sheet can be removed and the second fiber layer is applied to the other surface of the resin layer Can be applied.

The backing sheet can be applied before or after impregnation of the resin. However, it is typically applied before or during impregnation because it can provide a non-sticky surface which exerts the necessary pressure to impregnate the fiber layer with the resin. Which may be removed prior to adding additional layers of fibrous reinforcement or resin material.

The molding material may comprise reinforcing fibers in the form of a tow. The tow may be unidirectional or straightforward.

The tow used in the present invention is composed of a plurality of individual filaments. A single tow can have thousands of individual filaments. The tow and tow filaments are generally unidirectional with individual filaments aligned substantially parallel. Typically, the number of filaments in the tow can range from 2,500 to 10,000 or 50,000 or more. Approximately 25,000 tows of carbon filaments are available from Toray, and tows of approximately 50,000 carbon filaments are available from Zoltek.

The reinforcing fibers can comprise synthetic or natural fibers or any other type of material or combination of materials that can be combined with the resin composition of the present invention. Exemplary fibers include glass, carbon, basalt, natural or organic fibers, graphite, boron, ceramics and aramids and / or combinations of the above-mentioned fibers. Preferred fibers are carbon and glass fibers. Mixed or mixed fiber systems may also be considered. The weight of the fibers in the fiber reinforcement is generally 20-10000 g / m ² , preferably 50-800-2500 g / m ² , even more preferably 1200-2400 g / m ² , particularly preferably 150-600 g / g / m &lt; ² &gt; and / or a combination of the above-mentioned ranges. The number of carbon filaments per tow may vary from 3000 to 100,000, more preferably from 6,000 to 80,000, most preferably from 12,000 to 40,000, and / or combinations of the above-mentioned ranges. For fiberglass reinforcements, fibers of 600-2400 tex are particularly suitable.

The multi-filament tow used in the present invention may comprise cracked (i.e. stretched and broken), optionally discontinuous or continuous filaments. Filaments can be made from a wide variety of materials such as carbon, basalt fibers, graphite, glass, metallized polymers, aramids, and mixtures thereof. Glass and carbon fibers are preferred, and carbon fiber tow is preferred in the case of wind turbine shells having lengths of more than 40 meters, for example, 50 to 60 meters. Structural fibers are individual tufts composed of a plurality of unidirectional individual fibers. Typically, the fibers will have a circular or nearly circular cross-section with a diameter in the range of 3 to 20 μm, preferably 5 to 12 μm for carbon. For other fibers, including glass, the diameter may range from 3 to 600 μm, preferably from 10 to 100 μm.

An exemplary fabric includes B315-E05 manufactured by Devold. In one embodiment, such a fabric is produced by aligning the fiber tow at 30 degrees with respect to the longitudinal direction, cutting the tow, and applying a support structure, such as stitching, in the 0 degree direction. Another exemplary fabric is B310NW / G supplied by Saertex. The fabric may include multiple unidirectional tow layers coupled to form a multi-directional fabric. The fabric is provided with a backing fiber having an area weight of from 2 to 200 gsm (g / m ² ), or preferably from 4 to 100 gsm, or more preferably from 5 to 50 gsm, even more preferably from 6 to 15 gsm . The yarns may be applied with a stitch length of from 0.5 to 15 mm, preferably from 1 to 10 mm, or more preferably from 2 to 5 mm, or even more preferably from 2.5 to 3.8 mm. The fabric may be supplied in a width of 10 mm to 4000 mm, 200 to 4000 mm or more preferably 1200 to 3600 mm, 100 to 400 mm, 120 to 240 mm and / or a combination of the above-mentioned widths.

Examples of fabrics that may be suitable for use in the present invention may have substantially the following characteristics, preferably in combination with one or more of the following features, and the tow of the fabric has a linear mass density of 1200 tex And the supporting fibers may have a linear mass density of 34 tex: an area weight of 310 gsm (g / m ² ), including 300 gsm unidirectional tows arranged at 30 °; Stitching with 10 gsm fibers; Stitching applied in the longitudinal direction. Another fabric suitable for use in the present invention may have an area weight of 310 gsm in a tow arranged substantially at 30 or 45 degrees with respect to the longitudinal direction and the fabric may have an area weight of, for example, 10 gsm or 13 gsm And may include support fibers comprising fibers. A further example of a suitable fabric may be a tow substantially arranged at 30 [deg.] Or 45 [deg.] With respect to the longitudinal direction and having an area weight of substantially 600 gsm and a supporting layer of substantially 10 gsm or 13 gsm. Examples of fabrics that may be suitable for use in the present invention may have substantially the following characteristics: a 301 gsm unidirectional tow layer arranged at +45 or 30 [deg.], 301 gsm arranged at -45 or 30 [ An unidirectional tow layer, and an area weight of 1181 gsm, including 567 gsm unidirectional tow layers, which are combined with a 12 gsm fibrous support structure. The stitching fibers include polyethersulfone and can be applied to tricot stitches.

The molding material of the present invention may be produced from a commonly available epoxy resin which may contain a hardener and optionally an accelerator. In one embodiment, the epoxy resin may contain a hardener, such as dicyandiamide or a urea-based or urea-derived curing agent. The relative amounts of curing agent and epoxy resin to be used will depend on the reactivity of the resin and the nature and amount of the fiber reinforcement in the molding material.

When the epoxy resin composition comprises at least one urea-based curing agent, it is preferably used in an amount of 0.5 to 10 wt%, more preferably 1 to 8 wt%, even more preferably 2 to 8 wt%, based on the weight of the epoxy resin of the curing agent. Is preferably used. Preferred urea-based materials are those available under the commercial designations Urone®, such as UR500 and / or UR505, supplied by Alzchem. In addition to the curing agent, suitable accelerators are, for example, lanthanum amine-based curing agents such as dicyanopolyamide (DICY) or dicyandiamide.

The epoxy resin used in the material of the present invention preferably has a high reactivity such as an EEW of an epoxy equivalent weight (EEW) in the range of 150 to 1,500, preferably in the range of 200 to 500, Or a hardener. Suitable epoxy resins include combinations of two or more epoxy resins selected from monofunctional, bifunctional, trifunctional and / or functional epoxy resins.

Suitable bifunctional epoxy resins include, for example, diglycidyl ethers of bisphenol F, diglycidyl ethers of bisphenol A (optionally brominated), phenol and cresol epoxynovolak, glycidyl ethers of phenol-aldehyde adducts, A glycidyl ether of an aliphatic diol, a diglycidyl ether, a diethylene glycol diglycidyl ether, an aromatic epoxy resin, an aliphatic polyglycidyl ether, an epoxidized olefin, a brominated resin, an aromatic glycidyl amine, a hetero Cyclic glycidylimidines and amides, glycidyl ethers, fluorinated epoxy resins, glycidyl esters, or any combination thereof.

The difunctional epoxy resin may be selected from diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol A, diglycidyl dihydroxynaphthalene, or any combination thereof.

Suitable trifunctional epoxy resins include, for example, phenol and cresol epoxy novolak, glycidyl ether of phenol-aldehyde adduct, aromatic epoxy resin, aliphatic triglycidyl ether, dialiphatic triglycidyl ether, aliphatic polyglycidyl ether Cyclic amines, cydylamines, heterocyclic glycidylimines and amides, glycidyl ethers, fluorinated epoxy resins, or any combination thereof. Suitable trifunctional epoxy resins are available from Huntsman Advanced Materials (Monthey, Switzerland) under the trade names MY0500 and MY0510 (triglycidyl para-aminophenol) and MY0600 and MY0610 (triglycidyl meta- aminophenol). Triglycidyl meta-aminophenols are also available under the trade name ELM-120 from Sumitomo Chemical Co. (Osaka, Japan).

Suitable commercially available epoxy resins are commercially available from Mitsubishi Gas Chemical Company under the name Tetrad-X and from CVC Chemicals as Erisys GA-240 under N, N, N'N'-tetraglycidyl-m-xylylenediamine ), And N, N, N'N'-tetraglycidyl methylenedianiline (e.g., MY0720 and MY0721 from Huntsman Advanced Materials). Other suitable multifunctional epoxy resins include DEN438 (from Dow Chemicas, Midland, Mich.), DEN439 from Dow Chemicas, Araldite ECN 1273 from Huntsman Advanced Materials, and Araldite ECN 1299 from Huntsman Advanced Materials .

In a further embodiment, the resin may comprise an epoxy resin containing from 20 to 80% by weight of the epoxy resin of EEW (epoxy equivalent) of 150 to 1500, said resin having an external Lt; RTI ID = 0.0 &gt; temperature. &Lt; / RTI &gt; The epoxy resin may contain 0.5 to 10 wt% of a curing agent. The epoxy resin can be cured in the absence of a typical hardener such as dicyandiamide.

The epoxy equivalence can be calculated as follows: (molecular weight of epoxy resin) / (number of epoxy groups per molecule). Another method is to calculate the number of epoxies that can be defined as: epoxy number = 100 / epoxy equivalent. Calculations of epoxy groups per molecule: (epoxy number x molecular weight) / 100. Molecular weight calculation: (100 x epoxy groups per molecule) / epoxy number. Molecular weight calculation: epoxy equivalent x epoxy group per molecule. The present invention is particularly directed to providing a prepreg that can be based on a reactive epoxy resin that can be cured at lower temperatures with an acceptable molding cycle time.

In a further embodiment, the resin can be cured within 10 hours, especially within 8 hours. The curing agent may be urea-based. In a further embodiment, the molding material may comprise 20 to 85 wt% of an epoxy resin and 80 to 15 wt% of fibers.

The toughening material may include a resin that imparts a durability to the matrix. The toughening material may be applied as a separate layer or particle in the form of a veil, or may be mixed with a resin material. If the additional toughening material is a polymer, it should be insoluble in the matrix epoxy resin at room temperature or at an elevated temperature at which the resin is cured. Depending on the melting point of the thermoplastic polymer, it melts or softens to varying degrees during curing of the resin at elevated temperatures and can be re-solidified as the cured laminate cools. Suitable thermoplastic materials should not be soluble in the resin and include thermoplastic materials such as polyamide (PAS), polyethersulfone (PES), and polyetherimide (PEI). Polyamides such as nylon 6 (PA6) and nylon 12 (PA12) and mixtures thereof are preferred.

A stack of two or more materials of the present invention containing prepregs to produce a cured laminate may contain 40 or more prepreg layers, typically 60 or more layers and sometimes 80 or more layers, All of which are two or more substances of the present invention. One or more of the prepreg layers in the stack may be cured or pre-cured to partially process the resin in the prepreg layer. However, it is preferable that all of the prepregs are substances according to the present invention. Typically, the stack will have a thickness of 1 cm to 10 cm, preferably 2 cm to 8 cm, more preferably 3 to 6 cm.

The prepreg or prepreg stack, when produced, is cured by exposure to elevated temperatures and optionally elevated pressures to produce a cured laminate.

The curing process can be carried out at pressures below an absolute pressure of 2.0 bar, preferably below an absolute pressure of 1 bar. In a particularly preferred embodiment, the pressure is below atmospheric pressure. The curing process may be performed for a time sufficient to cure the thermosetting resin composition to a desired degree at one or more temperatures in the range of 80 to 200 占 폚.

Curing at a pressure close to atmospheric pressure can be achieved by a so-called vacuum bag technique. This involves putting the prepreg or prepreg stack in a sealed bag and creating a vacuum inside the bag. This has an effect that the prepreg stack is subjected to a solidifying pressure lower than the atmospheric pressure depending on the degree of vacuum to which the prepreg stack is applied.

When the prepreg or prepreg stack is cured, it becomes a composite laminate suitable for use in structural applications, for example, shells, spas or hubs of wind turbine blades.

The composite part or member according to the present invention can be used to form wind turbine blade shells or spars independently or to be connected to one or more additional such composite members by, for example, mechanical fastening means and / Turbine blade shells or spas. From such wind turbine blade shells and spas, the wind turbine blades advantageously make two such wind turbine blade shells by adhesives and / or mechanical means, for example by fasteners and by connecting them with spas with the assembly . Both of the wind turbine blade spas associated with the wind turbine blade shell may optionally include additional elements such as control elements, lightning conductors, and the like. In a particularly preferred embodiment, each blade shell is comprised of a composite member fabricable from the material of the present invention. In another preferred embodiment, the wind turbine blade shell member produced by the method according to the present invention comprises a complete outer shell of the wind turbine blade, i.e., a pressure side and a suction side integrally formed during fabrication of the wind turbine blade shell member . The blades may be formed as sections for assembly in situ, and these sections may be complete shells and spas, half shells, half spas, or any combination thereof, or may be assembled to form two or more lengths of blades .

Although the length and shape of the shell are different, the trend must use a longer blade (requiring a longer shell) that may require a thicker shell or a specific sequence of prepregs in the stack to be subsequently cured. Which impose certain requirements on the material from which they are made. A prepreg based on a unidirectional multifilament carbon fiber tow is preferred for blades 30 meters long or even more particularly for blades longer than 40 meters, for example 45 to 65 meters. The length and shape of the shell and spar can make use of different prepregs along the length of the shell. In terms of size and complexity, the preferred process for making wind energy components, such as shells and spas, is to provide a suitable curable material in a vacuum bag, which is placed in a mold and heated to a curing temperature. The bag may be degassed before or after being placed in the mold.

Reduction of the number of coats of the laminate obtained by the present invention and improved fiber alignment are particularly useful in providing shells and / or spas and / or spaps for wind turbine blades having uniform mechanical properties. In particular, spas and their parts are subjected to high loads. Any reduction in co-content or an increase in fiber alignment significantly improves the mechanical performance of such components. This in turn allows the part to be formed with reduced weight (e.g., by reducing the number of prepreg layers) compared to similar parts having a higher void content. In addition, in order to withstand the conditions given during use of the wind turbine structure, it is preferred that the cured prepreg from which the shell and spar are made has a high Tg, preferably a Tg of greater than 90 ° C.

The laminate produced from two or more of the materials of the present invention has a total volume of the laminate, measured by microscopic analysis, of 20 spaced cross sections measuring a 30 x 40 mm section (5 cm spacing) of the cured laminate sample , Typically less than 0.5% by volume, especially less than 0.1% by volume of cavities, based on the total weight of the composition. Sections were polished and analyzed under a microscope at a viewing angle of 4.5 to 3.5 mm to determine the surface area of the cavity with respect to the total surface area of each cross section of the sample and these measurements were averaged over the number of sections. Such a method for determining the fraction is used within the context of this disclosure, but alternatively, standardization methods such as DIN EN 2564 are available. However, this method is expected to provide comparative results for microscopic analysis as outlined herein. In addition, the maximum size of the cavity was evaluated in each viewing angle section, and this number was averaged over 20 samples. The average surface area of the cavity was obtained as the value of the cavity content by volume. The present inventors have found that a fraction or level as low as 0.01 vol% or less has been achieved.

The molding material of the present invention contains lower levels of cavities between tows. Thus, it is preferred that each molding material and molding material stack have a collecting value of less than 15% or less than 9%, more preferably less than 6%, most preferably less than 3%.

The collecting test determines the degree of watertightness or impregnation between the unidirectional tows of the stiffener layer in the molding material of the present invention. In this test, specimens of the molding material are initially weighed and clamped between the two plates in such a way that a 5 mm wide strip is projected. This arrangement is floating in the direction of the fibers in the water bath at room temperature (21 ° C) for 5 minutes. Thereafter, the specimen is removed from the plate, weighed again, and the weight difference provides a value for the specimen impregnation. The smaller the amount of water collected, the higher the degree of water resistance or impregnation.

Fiber alignment is described in Creighton et al. A Multiple Field Image Analysis Procedure for Characterization of Fiber Alignment in Composites; Composites: Part A 32 (2001) 221-229. First, the specimen was cut and ground into 1200 grit SiC paper. The ground surface was then immersed in acetone and lightly polished with a stainless steel scouring pad. Thereafter, a micrograph was obtained from the fabricated surface and analyzed with an automatic image analysis algorithm. The algorithm automatically detected structural features such as fibers and matrices. The algorithm generated a number of pixels representing the fiber, which was then used to calculate the tilt angle along the arrangement between adjacent pexels and to estimate the degree of fiber misalignment.

The present invention will now be illustrated by way of example only with reference to the accompanying drawings.

Figure 1 shows three different layups of a molding material according to embodiments of the present invention.

Fig. 2 shows a cross section of the lay-up 1 of Fig.

Fig. 3 shows a cross section of the lay-up 2 of Fig.

Fig. 4 shows a cross-sectional view of the lay-up 3 of Fig.

Figure 5 shows a cross-section of a microscope of the lay-up 1 of Figure 1;

Figure 6 shows a cross-section of a microscope of the lay-up 2 of Figure 1;

Figure 7 shows a cross-section of a microscope of the lay-up 3 of Figure 1;

8 shows a cross-sectional view of a layup of a prepreg layer in which wires exist.

9 is a cross-sectional view of a layup of a prepreg layer and a laminate layer in which the same wire is present.

10 shows a laminate structure according to another embodiment of the present invention.

Figure 11 shows a laminate structure according to a further embodiment of the present invention.

The invention is illustrated with reference to the following examples in which the following materials of the invention are used.

Prepreg 1) All unidirectional carbon fiber epoxy resin-based prepregs containing 66 wt% Panex, 35 carbon fibers and 34 wt% epoxy resin available from Hexcel as HexPly M 9.6 GF / 34% / UD 600.

Prepreg 2) A film of an epoxy resin in combination with a dry unidirectional glass fiber reinforcement on either side of a film of epoxy resin available from Hexcel as HexFit (R) 2000. The resin content is 35 wt%, and the outer surface of the material is dry and soft.

Prepreg 3) PolySpeed® GR 120, containing 2400 tex glass fibers with a weight of 1200 ± 60 g / m ² and containing 27 wt% of cured epoxy resin, available from Hexcel as a press-cured unidirectional glass fiber epoxy Laminate.

Prepreg 4) HexPly® M 9.6 All unidirectional glass fiber epoxy resin based prepregs containing 32% epoxy resin and 68% glass fiber available from Hexcel as GF / 32% / UD 800. A weave fleece of glass fiber weighing 50 gsm was adhered to the surface of the prepreg.

The prepreg was laid up on the following stack.

The distribution of the layers in the stack is shown in FIG. The stack was cured in a vacuum bag at 80 占 폚. The cured stack was evaluated for porosity and uniformity.

The porosity, appearance and uniformity of the cured materials of the rayon-ups 1, 2 and 3 of Figure 1 are shown in Figures 2, 3 and 4, respectively. Figures 5, 6 and 7, respectively, show a cross-sectional micrograph of each of these cured layups. In the drawings, reference numeral 1 denotes a prepreg 1, reference numeral 2 denotes a prepreg 2, and reference numeral 3 denotes a prepreg 3.

Figures 8 and 9 show that the use of a cured laminate in combination with the prepreg layer 3 in the stack produces a more regular and uniform surface even when the obstacle (wire 4) is present in the lay-up structure.

Figure 10 shows a molding material 20 in the form of multiple cured laminate layers 28,30 joined together by a layer of prepreg material 24. The cured laminate layers 28,30 comprise unidirectional fibers in the cured resin matrix 22 and dry fiber regions 26 in the longitudinal or warp direction. Instead of the dry fiber region 26, this region may also be in the form of a longitudinal gap or open area. The laminates 28, 30 may be pressure bonded or drawn and formed.

In use, the material 20 is a layup combined with other molding materials as previously described to form a composite laminate structure for later processing and curing to form composite parts.

The present inventors have found that such dry or impregnated areas improve the drape of the laminate in a composite mold. They also improve the venting of any trapped gas during processing and curing and improve the bond between the surrounding materials and the laminate in lay-up.

Figure 11 shows a molding material 30 in the form of a cured laminate layer 36 in the form of a cured resin-impregnated fiber reinforcement having a stiffener layer 32 joined together. Layer 32 may preferably be a dry fiber reinforcement layer or a prepreg material layer.

In use, the material 30 is a layup in combination with another molding material as previously described to form a composite laminate structure for later processing and curing to form the composite part. Layer 32 improves integration and bonding with other molding materials.

Claims (26)

i) a first molding material, further comprising a layer of fibrous material and a curable resin over one side of the curable resin matrix, and further comprising a layer of fibers adhered to the fibrous reinforcement material;
ii) a second molding material comprising a fibrous material comprising two cross-linked fiber ply, wherein each ply comprises fibrous tow oriented at different angles, and wherein the fibrous material comprises a curable resin matrix A second molding material comprising;
iii) a third molding material comprising together at least two stiffener layers having unidirectional fiber tows and a curable resin matrix bonding layer;
iv) a fourth molding material comprising a layer of fiber reinforcement and a curable liquid resin, wherein the fiber reinforcement comprises a plurality of tows, each tow comprising a plurality of filaments, the resin comprising a plurality of tows between tows of fiber reinforcement A fourth molding material, partially or wholly provided between the apertures, to provide a vent path in at least the interior of the tow; And
v) resin-impregnated fiber layer
A plurality of fiber-reinforced thermosetting resin layers selected from at least two of the fiber-reinforced thermosetting resin layers. The laminated structure of claim 1, comprising at least layers (i) and (iv). 3. Laminated structure according to claim 1 or 2, comprising layer (iii). A laminate according to any one of claims 1 to 3, comprising a layer of impregnated tow and non-impregnated tow joined together, wherein the longitudinal axis of the impregnated tow and the non-impregnated tow are located in the same plane. Structure. 6. Laminated structure according to any one of claims 1 to 4, comprising a layer (i) in which a fiber reinforcement is impregnated from one side of the material and an additional fiber layer is adhered to the opposite side of the fiber reinforcing material. 6. Method according to any one of claims 1 to 5, characterized in that the additional fiber layer has a thickness in the range of 200 to 2400 gsm, preferably 400 to 1600 gsm, more preferably 600 to 1200 gsm and / (I) comprising a nonwoven fibrous material having an areal weight of a combination of at least two layers of nonwoven fibrous material. 7. Laminated structure according to any one of claims 1 to 6, wherein the fiber-reinforced material comprises a fiber tow comprising filaments having an average diameter in the range of 1 to 20 占 퐉, preferably 10 to 15 占 퐉. 8. Laminated structure according to any one of claims 1 to 7, wherein the ply comprises a layer (ii) comprising carbon fibers. 9. Laminated structure according to any one of claims 1 to 8, comprising a layer (ii) which is sacrificed when the ply is striked by lightning. Use of the laminated structure according to any one of claims 1 to 9 for the production of parts of wind turbine blades. 11. Use according to claim 10, wherein the part is part or all of the shell. 11. Use according to claim 10, wherein the part is part or all of a spa. A wind turbine blade or part thereof comprising a first section and a second section, the first section comprising a first molding material according to any one of claims 1 to 8. A wind turbine blade or parts thereof. 14. The blade of claim 13, wherein the first section comprises a third molding material, the third molding material comprising two or more stiffener layers having a unidirectional fiber tow and a curable resin matrix bonding layer. 15. A blade or part according to claim 13 or 14, wherein the orientation of the fiber tow in each unidirectional fiber stiffener layer is different from the adjacent layer or layers. 16. A method according to any one of claims 13 to 15, wherein the second section comprises a fourth molding material comprising a stiffener layer having unidirectional fiber tows and a curable fiber matrix for impregnating the stiffener layer from one side , Wind turbine blades or parts thereof. 17. A wind turbine blade or article according to claim 16, wherein the stiffener layer comprises a permeable thermoplastic layer on the opposite side to which the layer is impregnated. 18. A wind turbine blade according to any one of claims 13 to 17, wherein the first section and / or the second section comprises a fifth molding material and the fifth molding material comprises a cured fiber reinforced laminate structure. Or parts thereof. A first molding material comprising a fiber-reinforced material impregnated from at least one side having a curable resin matrix, wherein the first molding material further comprises an additional fiber layer to which the molding material is adhered to the fiber-reinforcing material. 20. The first molding material of claim 19 wherein the fibrous reinforcement is impregnated from one side of the material and the additional fibrous layer is adhered to the opposite side of the fibrous reinforcement. 21. A first molding material according to claim 19 or 20, wherein the additional fiber layer comprises a nonwoven fibrous material having an area weight in the range of from 0.5 to 10 gsm, preferably from 1 to 4 gsm. 22. A method according to any one of claims 19 to 21, wherein the fiber reinforcing material comprises a fiber tow comprising filaments having an average diameter in the range of 1 to 20 占 퐉, preferably 10 to 15 占 퐉. . 23. A first molding material according to any one of claims 19 to 22, adapted for use in resin injection layup. CLAIMS 1. A second molding material comprising a fibrous material comprising two cross-linked fiber ply, wherein each ply comprises fiber tow oriented at different angles, wherein the fibrous material further comprises a curable resin matrix, 2 Molding material. 25. The second molding material of claim 24, wherein the ply comprises carbon fibers. 26. A second molding material as claimed in claim 24 or 25, wherein the second molding material is sacrificed when the ply is struck by lightening.

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