Method for improving adhesion of wind turbine blade components

Abstract

A method of manufacturing a wind turbine blade shell member (36, 38) is provided, the method comprising the steps of providing a blade mold (96) for the blade shell member, arranging one or more layers of fibrous material in a molding cavity to provide a fibrous stack (97), and providing a prefabricated spar cap member (62). A surface of the spar cap member is treated with a primer composition to provide a primer-treated surface. Heat is then applied to the primer-treated surface of the spar cap member to provide an activated surface in order to improve adhesion in subsequent resin co-infusion of the spar cap member and the fiber stack.

Description

Field of the Invention

[0001] The present invention relates to a method for improving the bonding of wind turbine blade components, in particular in the manufacture of a blade shell component including a spar cap for a wind turbine blade. In particular, the present invention relates to a method for manufacturing a wind turbine blade shell component and to the use of a silane-containing primer composition in improving the bond between a first wind turbine blade component and a second wind turbine blade component. Background of the Invention Climate change has created an urgent need for sustainable energy, making wind energy of particular interest as a cost-effective and clean energy source. A wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades that capture the kinetic energy of the wind using the known airfoil principle. With the ever-increasing demand for energy, modern wind turbines can have power ratings of more than 10 MW and can have rotor blades that are more than 100 meters in length.

[0003] Wind turbine blades are typically made of fiber-reinforced polymer materials and include a pressure side shell half and a suction side shell half. The cross-sectional profile of a typical blade includes an airfoil body for generating air flow (which results in a pressure difference between the two sides). The resulting lift generating torque is used to generate electricity. Wind turbine blades are typically manufactured by forming two shell parts or shell halves from multiple layers of woven fabric or fiber and resin. Spar caps or main laminates are placed or integrated in the shell halves and may be combined with shear webs or spar cross beams to form a structural support member. The spar caps or main laminates may be connected to the interior of the suction half and pressure half of the shell, or integrated in the interior.

[0004] As the size of wind turbine blades increases, various challenges arise due to the increased forces to which the blades are subjected during operation, which requires improved reinforcement structures. In some known solutions, pultruded fiber material strips are used to manufacture the spar caps. Pultrusion is a continuous process in which fibers are pulled through a supply of liquid resin and then heated in a chamber where the resin solidifies. Such pultruded strips can be cut to any desired length. Thus, the pultrusion process is generally characterized as a continuous process that produces composite parts with a constant cross-section. Thus, multiple pultrusions can be vacuum infused together in a mold to form the spar caps.

[0005] A typical spar cap may comprise a plurality of carbon pultruded elements and possibly one or more intermediate layers arranged between the carbon pultruded elements. Such spar caps may be produced directly in the wind turbine blade mould or in a separate off-line mould, where they are infused with resin and then subsequently lifted into the main blade shell mould which is then infused with resin.

[0006] Different resin combinations can be used for the spar caps and the main blade shells. It is crucial to ensure sufficiently strong adhesion between the shells and the prefabricated spar caps, as bonding the resin to the precast main spar is critical to the structural integrity of the blade. Vinyl ester or epoxy ester resins have good adhesion and are commonly used, while other resins such as polyester resins have attractive prices. However, the adhesion properties of polyester resins are low compared to vinyl ester and epoxy resins. The use of primers on the spar caps improves the adhesion properties of the resin interface. In the case of offline manufacturing of the spar caps, a primer may be applied to one or more surfaces of the spar caps before the spar caps are placed in the blade mold. Although primers can enhance bond strength, there are several challenges in terms of handling and process control.

[0007] Known primers are based on isocyanate chemistry and react immediately with moisture in the air. As a result, the effectiveness of the primer degrades over time, especially in high humidity. The time from application of the first primer layer to resin infusion is therefore critical, and extended processing times may affect primer performance and the structural integrity of the blade.

[0008] Furthermore, such known primers generally have a rather low flash point, which means high flammability and therefore a working hazard. Furthermore, known bonding methods that rely on the use of primers require prior abrasion of one or more surfaces of the prefabricated spar caps. This generally results in a dusty and noisy working environment, with associated health risks.

[0009] Therefore, an improved method of ensuring sufficiently strong adhesion between the shell and the prefabricated spar caps at reduced cost would be advantageous.

[0010] It is therefore an object of the present invention to provide an improved method of manufacturing a blade shell component including a spar cap.

[0011] Another object of the present invention is to provide a method for manufacturing a blade shell component with a reduced cost and having sufficiently strong adhesion between the shell and the prefabricated spar cap.

[0012] Another object of the present invention is to provide a method of manufacturing a blade shell member which is more efficient, safer and more environmentally friendly. Summary of the invention It has been found that one or more of the above objects can be achieved by a method for manufacturing a wind turbine blade shell component, the method comprising the steps of: providing a blade mold for a blade shell component, the blade mold comprising a molding cavity; arranging one or more layers of fiber material in the molding cavity to provide a fiber layup; providing a prefabricated spar cap component; treating a surface of the spar cap component with a primer composition to provide a primer-treated surface; applying heat to the primer-treated surface of the spar cap component to provide an activated surface; placing the spar cap component on top of at least a portion of the fiber layup in the molding cavity so that at least a portion of the activated surface of the spar cap component contacts the fiber layup; infusing the molding cavity with a resin; and curing the resin to form the blade shell component, wherein the primer composition comprises a silane compound.

[0014] Surprisingly it was found that this method improves the bond strength between the spar cap and the shell component by up to five times. In particular, it was found that the fracture toughness at the interface between the prefabricated spar cap component, in particular a component containing vinyl ester, and the fiber layup impregnated with polyester resin, in particular an unsaturated polyester resin, is greatly improved by the method of the invention. Furthermore, it was found that, in contrast to known methods of connecting spar caps to shell laminates, the method of the invention does not require spar cap rubbing operations, thereby providing a safer and more environmentally friendly working environment. Surprisingly, it was also found that the primer composition of the invention is stable to moisture in air, thereby significantly improving the storage time.

[0015] Using the method of the present invention, a spar cap component prefabricated, for example, by infusing a carbon fiber material with vinyl ester or epoxy ester in an offline spar cap mold can be optimally bonded to the inner shell surface by co-infusing the shell and spar cap with, for example, polyester infusion resin in a blade mold to form a spar cap reinforced wind turbine shell component. The resulting wind turbine shell component has sufficiently strong adhesion between the shell and the prefabricated spar cap at a reduced cost.

[0016] The method of the present invention is used to provide a blade shell member, such as a suction side shell member or a pressure side shell member. It should be understood that the same method can be used to provide a suction side shell member as well as a pressure side shell member. The only difference between providing a pressure side shell member and a suction side shell member will be the shape of the blade mould.

[0017] Wind turbine blades are typically made of two shell components or shell halves, a pressure side shell half and a suction side shell half. Such shell components are typically formed in separate open blade molds that conform to the aerodynamic shape of the shell halves, and the shell halves are subsequently connected together by a closed blade mold to form a wind turbine blade. Therefore, the wind turbine blade shell components manufactured by the method of the present invention are typically shell halves, such as shell halves with reinforcement structures (such as wing spar caps). The blade shell material may include one or more fiber layers and / or gel coatings. In a preferred embodiment, the longitudinal extension range L of the pressure side shell half and the suction side shell half is 50-120m, preferably 60-110m.

[0018] One or more layers of fiber material, preferably multiple layers of fiber material including glass fibers (e.g. fiberglass fabric), are arranged in the molding cavity to provide a fiber layup, typically including an outer surface facing the molding surface and conforming to the aerodynamic shape of the blade half, and an inner surface on which a spar cap component or multiple spar cap components are placed to form a spar cap reinforced shell component.

[0019] The prefabricated spar cap component may be a prefabricated spar cap. In some embodiments, the prefabricated spar cap component is a part of a spar cap of a wind turbine blade component to be produced, such as a pultruded plate. Thus, a plurality of spar cap components, such as a plurality of pultruded plates, may be placed in a mold to form the spar cap.

[0020] The prefabricated spar cap member is preferably an elongated element having an upper surface, a lower surface, a first side surface, a second side surface, a first end surface and a second end surface. Typically, the spar cap will extend over 60-95% of the length of the blade. Preferably, the spar cap comprises a plurality of such prefabricated spar cap members, such as a plurality of pultruded plates arranged in a stack. Preferably, the plurality of pultruded plates forming the spar cap will typically extend in the span direction of the shell half or blade. Thus, the length of at least some of the pultruded plates preferably corresponds to 60-95% of the length of the blade. A polymer resin, such as a polyester resin, in particular an unsaturated polyester resin, is typically co-infused into the fiber layup and the pultruded plates after all elements are arranged to form the shell half with the spar cap.

[0021] In some embodiments, the step of providing a prefabricated spar cap comprises the steps of providing a plurality of pultruded sheets comprising carbon fibers and optionally a plurality of intermediate layers comprising a fiber material to facilitate resin flow between the pultruded sheets; arranging the plurality of pultruded sheets into a stacked array, optionally wherein the plurality of pultruded sheets are separated by respective intermediate layers; and infusing and optionally curing the plurality of pultruded sheets with resin. The pultruded sheets are preferably elongated elements having a rectangular cross-section and are made of a fiber material comprising carbon fibers and a resin, preferably a vinyl ester resin. Alternatively, they may be hybrid pultruded elements comprising a second reinforcing fiber, such as glass fibers. The optional intermediate layers may comprise a fiber material, such as glass fibers or a polymer material, for facilitating resin flow between the pultruded sheets.

[0022] Preferably the prefabricated spar cap member comprises a fibre material, such as carbon fibre, preferably pultruded carbon fibre, which has been infused with a vinyl ester or epoxy resin to form the prefabricated spar cap member. The spar cap member in the form of a pultruded sheet is preferably manufactured by passing a resin impregnated, preferably vinyl ester impregnated, fibre material tow through a pultrusion die. The continuous pultruded strip exiting the pultrusion die may preferably be cut into individual pultruded sheets, for example of lengths between 30 and 200 metres, preferably between 50 and 100 metres, by using a cutting machine. The shaped impregnated sheet is then preferably cured to form the prefabricated spar cap member.

[0023] The prefabricated spar cap member may have an upper surface, a lower surface, a first side surface, a second side surface, a first end surface, and a second end surface. Typically, the prefabricated spar cap member is arranged in the molding cavity such that the lower surface of the prefabricated spar cap member contacts the fiber layup of the shell. In some embodiments, the upper surface and the lower surface of the spar cap member are preferably arranged relative to each other and may have substantially the same size. In the same manner, the first side surface and the second side surface of the spar cap member may be arranged relative to each other and have substantially the same size, and the first end surface and the second end surface may be arranged relative to each other and preferably have substantially the same size.

[0024] In the case where the prefabricated spar cap member is or comprises a pultruded sheet, the pultruded sheet length is typically between 50-150 meters, preferably between 50-100 meters, more preferably between 70-100 meters. The height / thickness of the pultruded sheet is preferably between 2-10 mm, preferably between 3-7 mm, most preferably between 4-6 mm. The width of the sheet is preferably between 20-300 mm, most preferably between 80-150 mm. In a preferred embodiment, the reinforcement structure, such as a spar cap, comprises 1-15 stacks of pultruded sheets arranged adjacent to each other, more preferably 3-9 stacks of pultruded sheets arranged adjacent to each other. Each stack may comprise up to 20 pultruded sheets stacked on top of each other, such as 2-20 pultruded sheets or 2-10 pultruded sheets. Thus, each reinforcement portion, such as each spar cap, may comprise 10-200 pultruded sheets.

[0025] The pultruded fiber material preferably includes a plurality of carbon fiber material tows or rovings forming a pultruded carbon fiber preform, and a plurality of glass fiber material tows or rovings. Therefore, each pultruded plate may include a total of 20-200 fiber material tows. The tows will generally extend along the length direction of the pultruded plate, i.e. substantially parallel to its longitudinal axis, or parallel to the span direction when arranged in the blade shell. In a preferred embodiment, the fiber material tows are arranged into a regular array or a regular grid consisting of tows in rows and columns, as shown in a vertical cross section of the pultruded plate. The pultruded plate preferably includes at least 10 rows and at least 10 columns of tows.

[0026] The step of treating (eg, impregnating) the surface of the spar cap member with a primer composition to provide a primer treated surface is preferably performed using a brush (eg, a foam brush) or by using a roller device. In some embodiments, the primer composition may be applied using a spray gun.

[0027] It is particularly preferred that at least the lower or bottom surface of the spar cap member is treated with the primer composition of the present invention. The lower or bottom surface of the spar cap member is the surface that faces and contacts the fiber layup in the blade mold when the spar cap is arranged in the blade mold. Thus, the lower or bottom surface of the spar cap member is the surface that faces the inner shell surface of the blade shell member. In some embodiments, other surfaces of the spar cap member are also treated with the primer composition, such as the upper or top surface of the spar cap member, and / or the side or end surfaces.

[0028] In some embodiments, the fiber layup includes a predetermined mounting area for placement of prefabricated spar cap components. In some embodiments, the predetermined mounting area on the fiber layup is also treated with a primer composition. In some embodiments, the predetermined mounting area for placement of the prefabricated spar cap components may include a recess formed in an inner surface of the shell material, i.e., an upwardly facing surface of the fiber layup within the mold cavity.

[0029] The surface of the spar cap member may be treated with the primer composition so that the surface is impregnated with the primer composition. In a preferred embodiment, the primer composition is applied to the surface of the spar cap member in an amount of 20-50 g / m2, preferably in an amount of 30-35 g / m2.

[0030] Primer composition of the present invention is preferably a liquid composition, preferably comprising an organic solvent. Preferably, the silane compound of the primer composition is an organosilane compound. Primer composition of the present invention may include or may be derived from one or more reactive silanes containing both organic functional groups and hydrolyzable groups. Advantageously, such silane compounds participate in crosslinking reactions, but also establish bonding between silicone networks and substrates. Silane compounds of the present invention are preferably derived from the hydrolysis of silanes with the general structure RSiX3, wherein R is or comprises a reactive organic functional group, and X is or comprises a hydrolyzable group, such as a methoxy group, an ethoxy group or an acetoxy group. Preferably, the silane compound of the primer composition comprises a silanol group. Such silanol groups advantageously allow condensation reactions to occur, which result in the formation of Si-O-Si bonds between silane monomers. Advantageously, the organic functional groups of the silane compound react with chemically reactive groups present in the resin (preferably polyester resin, most preferably unsaturated polyester resin) used to pour the blade molding cavity. The organic functional group may be selected from an aminoalkyl group, a mercaptoalkyl group, an epoxyalkyl group, an ureidoalkyl group, an acrylate group, and an isocyanurate group.

[0031] In a preferred embodiment, the silane compound of the present invention comprises a (meth)acrylate group, preferably a (meth)acrylic acid end group. In a preferred embodiment, the silane compound comprises a methacryloxy moiety, such as a (methacryloxy)alkyl moiety, such as a (methacryloxy)propyl group. In a preferred embodiment, the silane compound is a methacrylate functional silane.

[0032] Preferably, the silane compound is a hydroxysilylalkyl methacrylate, or comprises a hydroxysilylalkyl methacrylate, or is polymerized from a hydroxysilylalkyl methacrylate. In a particularly preferred embodiment, the silane compound comprises 3-(trihydroxysilyl)propyl methacrylate or is polymerized from 3-(trihydroxysilyl)propyl methacrylate. In a preferred embodiment, the silane compound is an oligomeric or polymeric silane compound, preferably a polymeric organoalkoxysilane compound. In a particularly preferred embodiment, the silane compound is a polymeric organoalkoxysilane compound comprising a (meth)acrylate group, preferably a methacrylate group.

[0033] In a preferred embodiment, the silane compound is capable of forming a polymeric silane compound, preferably a polymeric organoalkoxysilane compound. In a particularly preferred embodiment, the silane compound is capable of forming a polymeric organoalkoxysilane compound comprising a (meth)acrylate group, preferably a methacrylate group.

[0034] In a particularly preferred embodiment, the silane compound of the primer composition is obtainable by hydrolysis of trialkoxysilylpropyl methacrylate, preferably 3-(trimethoxysilyl)propyl methacrylate. It is particularly preferred that the silane compound of the present invention is an oligomer or polymer obtained by polymerization of 3-(trimethoxysilyl)propyl methacrylate monomer. Therefore, it is preferred that the silane compound of the primer composition comprises polymerized 3-(trimethoxysilyl)propyl methacrylate.

[0035] In a preferred embodiment, the silane compound is obtained by hydrolysis of an alkoxysilane monomer or an organoalkoxysiloxane monomer, preferably an organoalkoxysilane having a trimethoxysilane moiety and a methacrylate moiety, optionally followed by a condensation reaction between the hydrolyzed silane compounds, preferably polycondensation via silanol groups, to form siloxane bridges (Si-O-Si). In some embodiments, when applied to a surface, such as a surface of a spar cap member, preferably a spar cap member containing a vinyl ester resin, a condensation reaction between the hydrolyzed silane compounds, preferably polycondensation via silanol groups, to form siloxane bridges (Si-O-Si) is preferably performed.

[0036] Therefore, it is preferred that the silane compound is a polymerized silane compound obtained by forming a siloxane bond via silanol condensation, or the silane compound is polymerizable to form a polymerized silane compound obtained by forming a siloxane bond via silanol condensation.

[0037] In a preferred embodiment, the silane compound or its precursor comprises methacryloxy functional groups and methoxysilane functional groups. The methacryloxy functional groups can advantageously be used for free radical curing using a suitable resin, such as an unsaturated polyester resin, which can advantageously be used for infusing the blade moulding cavity. This advantageously leads to a strong bond between the shell fibre material and the primer treated spar cap member. Therefore, it is particularly preferred that the silane compound is obtained by hydrolysis of γ-methacryloxypropyltrimethoxysilane followed by condensation, preferably polycondensation, via the corresponding silanol groups of the monomers.

[0038] Prior to the step of applying heat to the primer treated surface of the spar cap member, the method of the present invention may comprise the step of drying the primer treated surface of the spar cap member and / or the fiber layup. The drying step may be performed at a temperature of 20-40°C for a period of 10-150 minutes.

[0039] The step of applying heat to the primer treated surface of the spar cap member to provide an activated surface preferably comprises heating the primer treated surface to a temperature of 80-130°C, preferably 90-120°C. Preferably, in the heat activation step, covalent bonds are formed between the silane compound of the primer composition and the resin (preferably vinyl ester resin) of the spar cap member. In a preferred embodiment, the step of applying heat to the primer treated surface comprises heating the primer treated surface to a temperature of 80-130°C, preferably 90-120°C, for a period of 3-60 minutes, preferably 5-30 minutes. The heating step is preferably performed using an infrared heating device. Using such a device, it was found that the treated spar cap surface can reach the required heating temperature, for example >120°C, in less than 30 seconds, thereby achieving a particularly efficient process. It was also surprisingly found that when such heating conditions are used, there is no risk of spar deformation because the maximum temperature at a depth of 8mm below the spar cap surface is less than 85°C.

[0040] The step of placing the spar cap member on top of at least a portion of the fiber layup in the moulding cavity preferably comprises placing the spar cap on a predetermined spar cap mounting area on the fiber layup, i.e. on an inner or upwardly facing surface of the fiber layup in the blade mould. At least a portion of said activated surface of the spar cap member, preferably the lower or bottom surface of the spar cap, is placed in contact with the fiber layup. Bonding advantageously occurs at the interface between the fiber layup and the treated surface of the spar cap member.

[0041] The spar cap members are typically fixed to the inner surface of the shell members (e.g. shell halves). The step of placing the spar cap members (which may be in the form of pultruded sheets) on the fiber layup in the mold cavity preferably comprises arranging the pultruded sheets into adjacent stacks of pultruded sheets, wherein adjacent means substantially in the chord-wise direction. These stacks typically extend in the general spanwise direction of the shell halves. The step of combining the spar cap members (e.g. pultruded sheets) with the blade shell material to form the blade shell member typically comprises a resin infusion step, wherein the pultruded sheets and the blade shell material are co-infused with a resin, preferably a polyester resin (e.g. an unsaturated polyester resin), for example in a VARTM process.

[0042] Therefore, in the step of infusing the moulding cavity with resin and curing the resin to form the blade shell component, the fibre lay-up and the spar cap component having an activated surface are preferably co-infused with a resin such as epoxy, polyester or vinyl ester. A particularly preferred resin for this step is a polyester resin, preferably an unsaturated polyester resin.

[0043] In preferred embodiments, the prefabricated spar cap member has a top surface and an opposing bottom surface. In some embodiments, the primer composition is applied to at least the bottom surface of the spar cap member. In some embodiments, the primer composition is applied to both the bottom and top surfaces of the spar cap member. In some embodiments, the primer composition is applied to all surfaces of the spar cap member prior to placing the spar cap member in the blade mold.

[0044] In a preferred embodiment, providing a prefabricated spar cap member comprises the steps of providing a plurality of pultruded carbon elements, arranging the plurality of pultruded carbon elements in a stacked arrangement, and infusing the plurality of pultruded carbon elements with a resin, preferably a vinyl ester resin, and curing the resin to provide the prefabricated spar cap member.

[0045] In a preferred embodiment, the step of infusing the molding cavity with a resin comprises infusing the molding cavity with a polyester resin, preferably an unsaturated polyester resin. In a preferred embodiment, the step of infusing the molding cavity with a resin is performed by vacuum assisted resin transfer molding.

[0046] In a preferred embodiment, the prefabricated spar cap components comprise a vinyl ester resin. In a preferred embodiment, the prefabricated spar cap components have been infused with a vinyl ester resin during their manufacture.

[0047] In a preferred embodiment, the silane compound is a polymer comprising repeating units of formula (I): wherein X is an organic group, preferably a non-hydrolyzable organic group, preferably selected from amino, vinyl, epoxy, methacrylate, thio, alkyl, alkenyl, alkynyl, most preferably methacrylate, and wherein R is a spacer, such as -(CH2) n -, wherein n is 0 to 1000, preferably 1-5, most preferably 3.

[0048] In a preferred embodiment, the silane compound can be polymerized to form a polymer comprising repeating units of formula (I): wherein X is an organic group, preferably a non-hydrolyzable organic group, preferably selected from amino, vinyl, epoxy, methacrylate, thio, alkyl, alkenyl, alkynyl, most preferably methacrylate, and wherein R is a spacer, such as -(CH2) n -, wherein n is 0 to 1000, preferably 1-5, most preferably 3.

[0049] In a preferred embodiment, the silane compound is derived from XR 1 -Si(OR 2)3 monomer hydrolysis and subsequent condensation (polymerization), wherein X is a non-hydrolyzable organic group, such as amino, vinyl, epoxy, methacrylate, thio, alkyl, alkenyl, alkynyl, preferably methacrylate; R1 is a spacer, such as -(CH2) n -, wherein n is 0 to 1000, preferably 1-5, most preferably 3; R 2 Independently selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted aryl, optionally substituted 5-10 membered heteroaryl and optionally substituted 5-10 membered heterocyclyl, preferably alkoxy, most preferably methoxy.

[0050] In a preferred embodiment, the step of providing an activated surface comprises forming chemical bonds between the silane compound of the primer composition and hydroxyl groups of the spar cap components, preferably hydroxyl groups of the vinyl ester resin of the spar cap components, by applying heat to the primer treated surface of the spar cap components.

[0051] In a preferred embodiment, the resin is an unsaturated polyester resin, and the step of curing the resin to form the blade shell member comprises a free radical cross-linking reaction between the silane compound or its polymer and the unsaturated polyester resin, preferably a free radical cross-linking reaction between the (meth)acrylate groups of the silane compound or its polymer of the primer composition and the unsaturated polyester resin.

[0052] In a preferred embodiment, the primer composition comprises a carrier solvent, wherein the carrier solvent comprises 1-methoxy-2-propanol and a dicarboxylic acid ester, such as dimethyl glutarate, dimethyl succinate and dimethyl adipate or a mixture thereof, such as a mixture containing 57-67 wt% of dimethyl glutarate, 18-28 wt% of dimethyl succinate and 8-22 wt% of dimethyl adipate. In a preferred embodiment, the weight ratio of 1-methoxy-2-propanol to dicarboxylic acid ester is 1:2 to 2:1, preferably 1:1.2 to 1.2:1. Such a mixture has been found to be both compatible with silanes and sufficiently non-flammable. Therefore, in a preferred embodiment, the flash point of the primer composition is at least 39°C.

[0053] According to some embodiments, the method of the present invention further comprises the step of arranging one or more shear webs in at least one shell member (e.g., one of the shell halves), typically at the location of the reinforcement structure. Each shear web may include a web body, a first web root flange located at a first end of the web body, and a second web root flange located at a second end of the web body. In some embodiments, the shear web is substantially I-shaped. Alternatively, the shear web may be substantially C-shaped.

[0054] In another aspect, the present invention relates to a wind turbine blade shell component obtainable by the method of the present invention. The skilled person will appreciate that during the method of the present invention, the chemical composition of various compounds, particularly at the interface of the primer and the resin, will change. For example, preferably, the spar cap component comprises a vinyl ester resin such that the hydroxyl groups (OH) of the vinyl ester resin in the surface of the spar cap component can form hydrogen bonds with the primer-treated surface of the spar cap component. When the primer-treated surface is heated, covalent bonds can form between the polymerized organoalkoxysilane of the primer and the vinyl ester of the spar cap component. Thus, it was found that, as a direct result of the method steps, the method of the present invention causes the primer composition to be firmly bonded to the surface of the spar cap component. Thus, it was surprisingly found that the spar cap reinforced wind turbine blade shell component (e.g., shell half) is characterized by greatly improved bonding strength and fracture toughness compared to shell components obtained by known processes.

[0055] For a wind turbine blade shell component obtainable by the method of the present invention, it is particularly preferred that at least the lower or bottom surface of the spar cap component has been treated with the primer composition of the method of the present invention. The lower or bottom surface of the spar cap component is the surface that faces and contacts the fiber layup in the blade mould when the spar cap is arranged in the blade mould. Thus, the lower or bottom surface of the spar cap component is the surface that faces the inner shell surface of the blade shell component. In some embodiments of the wind turbine blade shell component, other surfaces of the spar cap component (e.g. the upper or top surface of the spar cap component, and / or the side or end surfaces) have also been treated with the primer composition when carrying out the method of the present invention.

[0056] The wind turbine blade shell component obtainable by the method of the invention may be a suction side shell component or a pressure side shell component, or it may be a wind turbine blade.

[0057] The invention also relates to a wind turbine blade having a pressure side shell half and a suction side shell half, wherein the suction side shell half and the pressure side shell half are connected along the leading edge and the trailing edge of the blade. One or both of the suction side shell half and the pressure side shell half can be obtained by the method of the invention.

[0058] In another aspect, the present invention relates to the use of a silane-containing primer composition for improving the bond between a first wind turbine blade component and a second wind turbine blade component by treating the surface of the first wind turbine blade component and / or the second wind turbine blade component with the primer composition and thereafter connecting and co-infusing the first wind turbine blade component and the second wind turbine blade component with a resin, preferably a polyester resin, most preferably an unsaturated polyester resin. Preferably, the blade components are connected along the primer-treated surface.

[0059] The primer composition having the described use is preferably a liquid composition, preferably comprising an organic solvent.Preferably, the silane compound of the primer composition is an organosilane compound, as described in detail above.

[0060] The first wind turbine blade component is preferably a fiber reinforced shell part, such as a shell half including a predetermined spar cap mounting area, and the second wind turbine blade component is preferably a spar cap or a main laminate. Preferably, the second component comprises vinyl ester resin and / or has been manufactured by infusing a fiber material, preferably comprising carbon fibers, with vinyl ester resin.

[0061] The use preferably further comprises applying heat to the primed first wind turbine blade component and / or the primed second wind turbine blade component to provide an activated surface before joining and co-infusing the first wind turbine blade component and the second wind turbine blade component with resin.

[0062] All features and embodiments discussed above with respect to the method for producing a wind turbine blade shell component are equally applicable to the use of the silane-containing primer composition and the wind turbine blade shell component of the present invention, and vice versa.

[0063] As used herein, the term "silane" refers to a compound containing a silicon atom in the backbone. The term "silane" may refer to an organic compound containing one or more silicon atoms. Thus, the term "silane" may refer to any silicon analog of a substituted or unsubstituted hydrocarbon. As used herein, the term "silane" may include a mixture of different silane compounds.

[0064] As used herein, the term "methacrylate functional silane" refers to a silane comprising a methacrylate functional group. Methacrylate is a derivative of methacrylic acid.

[0065] As used herein, the term "spanwise" is used to describe a direction along a blade from its root end to its tip end. In some embodiments, the spanwise direction is a direction along the longitudinal axis and longitudinal extension of a wind turbine blade.

[0066] Description of the invention

[0067] The invention is explained in detail below with reference to the embodiments shown in the accompanying drawings, in which: Figure 1 A wind turbine is shown, Figure 2 A schematic diagram showing a wind turbine blade, Figure 3 A schematic diagram showing a cross section of a wind turbine blade, Figure 4is a schematic top view of a shell half of a wind turbine blade according to the invention, Figure 5 is a schematic diagram illustrating the various stages of preparing and using the silane-based primer of the present invention, Figure 6 The various steps of the method for manufacturing a blade shell member according to the present invention are illustrated, Figure 7 is a graph of the measured bond strengths between wind turbine blade components, and Figure 8 is a graph of the bond strength between two wind turbine blade components as a function of time.

[0068] Detailed Description of the Drawings Figure 1 A conventional modern upwind wind turbine according to the so-called "Danish concept" is illustrated, having a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor axis. The rotor comprises a hub 8 and three blades 10 extending radially from the hub 8, each blade 10 having a blade root 16 closest to the hub and a blade tip 14 farthest from the hub 8. The rotor has a radius indicated as R.

[0069] Figure 2 A schematic diagram of a wind turbine blade 10 is shown. The wind turbine blade 10 has the shape of a conventional wind turbine blade and includes a root region 30 closest to the hub, a profiled or airfoil region 34 farthest from the hub, and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 includes a leading edge 18 facing the direction of rotation of the blade 10 when the blade is mounted on the hub, and a trailing edge 20 facing in the opposite direction of the leading edge 18.

[0070] The airfoil region 34 (also referred to as the profiled region) has an ideal or almost ideal blade shape for generating lift, while the root region 30 has a substantially circular or elliptical cross section due to structural considerations, which, for example, makes it easier and safer to mount the blade 10 to the hub. The diameter (or chord) of the root region 30 may be constant along the entire root region 30. The transition region 32 has a transition profile that gradually changes from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 generally increases with increasing distance r from the hub. The airfoil region 34 has an airfoil profile in which the chord extends between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with increasing distance r from the hub.

[0071] The shoulder 40 of the blade 10 is defined as the location where the blade 10 has its maximum chord length. The shoulder 40 is generally disposed at the boundary between the transition region 32 and the airfoil region 34. Figure 2Also illustrated is the longitudinal extension L, length or longitudinal axis of the blade.

[0072] It should be noted that the chords of the different sections of the blade do not usually lie in the same plane, since the blade may be twisted and / or curved (i.e. pre-bent), thereby providing a chord plane of a specifically corresponding twisted and / or curved course, this being in order to compensate for the most common case of the local velocity of the blade depending on the radius from the hub. The blade is usually made of a pressure side shell part 36 and a suction side shell part 38 glued to each other along a join line at the leading edge 18 and the trailing edge 20 of the blade.

[0073] Figure 3 A schematic diagram of a cross section of a blade is shown. As mentioned previously, the blade 10 comprises a pressure side shell portion 36 and a suction side shell portion 38. The pressure side shell portion 36 comprises a spar cap 41, also referred to as a main laminate, which constitutes a load-bearing portion of the pressure side shell portion 36. The spar cap 41 comprises a plurality of fiber layers 42, which mainly comprise unidirectional fibers arranged in the longitudinal direction of the blade in order to provide stiffness to the blade. The suction side shell portion 38 further comprises a spar cap 45, which comprises a plurality of fiber layers 46. The pressure side shell portion 36 may also comprise a sandwich core material 43, which is typically made of balsa wood or foamed polymer and sandwiched between several fiber reinforced skin layers. The sandwich core material 43 is used to provide stiffness to the shell in order to ensure that the shell substantially maintains its aerodynamic properties during rotation of the blade. Similarly, the suction side shell portion 38 may also comprise a sandwich core material 47.

[0074] The spar caps 41 of the pressure side shell part 36 and the spar caps 45 of the suction side shell part 38 are connected via a first shear web 50 and a second shear web 55. In the illustrated embodiment, the shear webs 50, 55 are formed as substantially I-shaped webs. The first shear web 50 comprises a shear web body and two web root flanges. The shear web body comprises a sandwich core material 51, such as balsa wood or foamed polymer, covered by several skin layers 52 made of several fiber layers. The blade shells 36, 38 may include additional fiber reinforcements at the leading edge and the trailing edge. Typically, the shell parts 36, 38 are bonded to each other via glued flanges.

[0075] Figure 4 is a schematic top view of a shell half 38 of a wind turbine blade according to the present invention, illustrating the location of a reinforcement structure 62 (e.g. a spar cap) having a spanwise extension Se. In the illustrated embodiment, the reinforcement structure 62 comprises three adjacent pultruded sheet stacks 66a, 66b, 66c. Figure 4As seen in FIG. 1 , the elongated reinforcement structure 62 extends substantially spanwise of the blade with adjacent pultruded sheet stacks 66a, 66b, 66c. The elongated reinforcement structure 62 has a tip end 74 proximate the tip end of the blade and a root end 76 proximate the root end of the blade. The elongated reinforcement structure also includes a spanwise extending leading edge 78 proximate the leading edge 18 of the blade and a spanwise extending trailing edge 80 proximate the trailing edge 20 of the blade.

[0076] Figure 5 is a schematic diagram illustrating the various stages of preparing and using the silane-based primer of the present invention on the surface 63 of a prefabricated spar cap member 62. First, the organoalkoxysilane monomer 85 is hydrolyzed, see step 90. The moiety X preferably includes a methacrylate moiety. Preferably, RO / OR is an alcohol moiety. Then, step 91, the hydrolyzed monomer is polymerized in a condensation reaction to form a polymer 87 having a siloxane bridge (Si-O-Si). Then, step 92, the surface 63 of the spar cap member 62 is treated with the primer composition including the polymer 87. Preferably, the spar cap member 62 includes a vinyl ester resin so that the hydroxyl groups (OH) of the vinyl ester resin in the surface 63 of the spar cap member 62 can form hydrogen bonds 88 with the spar cap member surface 63. Step 93, after heating the primer-treated surface, covalent bonds 89 are formed between the polymerized organoalkoxysilane 87 and the vinyl ester of the spar cap member, resulting in a strong bond between the primer composition and the spar cap member surface.

[0077] Figure 6 The various steps of a method of manufacturing a blade shell component according to the present invention are illustrated. A prefabricated spar cap component 62 is provided, which has a top surface 61 and an opposite bottom surface 63, wherein the bottom surface will contact and bond with the fiber layup of the shell component (e.g. shell half). First, for example, by using a Figure 6 A spray gun 94, moved by the arrow shown in a, treats the lower surface 63 of the spar cap member 62 with a primer composition, preferably a liquid primer composition. However, other techniques may be used, such as application by brush, or application by various other application techniques.

[0078] Next, heat is applied to the primer treated surface 63 to provide an activated surface. This may be done, for example, by using a suitable heating device 95 (e.g. an infrared device) that is moved along the spar cap member surface 63, such as Figure 6 Preferably, the temperature applied during the heating step is 90-120°C.

[0079] Then, if Figure 6 c and Figure 6d, a spar cap member 62 is placed on top of at least a portion of the fiber layup in the mould cavity such that at least a portion of said activated surface 63 of the spar cap member contacts the fiber layup 97. The fiber layup 97 has been prepared in a known manner using a blade mould 96 having a mould cavity 98 in which a plurality of fiber layers, such as glass fiber layers, are typically placed to form a shell portion.

[0080] Next, the mold cavity is infused with resin. Figure 6 As shown in Fig. 5, this can be done by placing a vacuum bag 99 on top of the fibre lay-up and spar cap components and then infusing the resin in a VARTM process from inlet channels 100. The mould cavity is preferably infused with a polyester resin, preferably an unsaturated polyester resin.

[0081] The resin is then cured to form a hardened blade shell member. Preferably, the step of curing the resin to form the blade shell member comprises a free radical crosslinking reaction between the silane compound and the unsaturated polyester resin, preferably a free radical crosslinking reaction between the (meth)acrylate groups of the silane compound of the primer composition and the unsaturated polyester resin.

[0082] Example 1 Figure 7 It is a graph showing the critical energy release rate (GIC) measured under different conditions. GIC is the value of the energy release rate G in a pre-cracked specimen when crack growth starts under plane strain loading conditions. It is expressed in joules per square meter, J / m2 or N / m. Figure 7 The GIC measured according to ISO / DIS 13586 (en) for two connected blade parts using a silane-containing primer according to the invention in combination with an unsaturated polyester resin, wherein the polyester cure cycle was 16 hours at 40° C. (column A), 4 days at room temperature (column B), 3 hours at 90° C. (column C), and without any primer (column D) is shown. Surprisingly, it was found that the GIC using the method according to the invention (columns A, B, C) was about 5 times higher than the same cure with an unsaturated polyester resin without the use of a silane-based primer (column D). It can be seen from this that the method according to the invention involves a combination with a high resistance to unstable crack growth.

[0083] Example 2 The effect of humidity on primed spar cap surfaces using the silane-based primer of the present invention was tested over time wherein the surfaces, which had been treated with the primer and then heated to activate the surface, were exposed to 80% relative humidity at room temperature. Figure 8 On the x-axis is shown the time (in days) and on the y-axis is the GIC (in N / m). Figure 8As can be seen in Figure 2, there is only a minor effect on the bond strength between two wind turbine blade components over time. This shows that the primer treated wind turbine blade components are surprisingly stable over extended periods of time.

[0084] Example 3: Preparation of primer composition The primer composition according to one embodiment of the present invention can be prepared by implementing the following steps: · Dibasic ester RPDE (containing 57-67% by weight of dimethyl glutarate, 18-28% by weight of dimethyl succinate, and 8-22% by weight of dimethyl adipate) and 1-methoxy-2-propanol were added to a clean mixing vessel to provide a 1:1 weight ratio of dibasic ester to 1-methoxy-2-propanol, Add distilled vinegar or a 7wt% acetic acid / 93wt% premix to the mixing vessel while slowly stirring, Mix for 5-10 minutes until a homogeneous mixture is obtained. Add Silquest A174NT (γ-methacryloxypropyltrimethoxysilane) to the mixing vessel while stirring slowly. Stir for 60 minutes, • The resulting primer composition is dispensed into containers which are then sealed.

[0085] In the final primer, the dibasic ester The weight percentage of RPDE was 46.2%, the weight percentage of 1-methoxy-2-propanol was 46.3%, the weight percentage of distilled vinegar (or a premix of 7 wt % acetic acid / 93 wt %) was 5%, and the weight percentage of SilquestA174NT was 2.5%.

[0086] The invention is not limited to the embodiments described herein and changes or modifications may be made without departing from the scope of the invention.

[0087] List of Reference Numerals 4 Tower 6. Cabin 8 Hub 10 blades 14 Leaf tip 16 Blade root 18 Leading Edge 20 trailing edge 30 Root Zone 32 Transition Zone 34 Airfoil area 36 Pressure side casing part 38 Suction side shell part 40 Shoulders 41 Spar cap 42 Fiber Layer 43 Sandwich core material 45 Spar cap 46 Fiber Layer 47 Sandwich core material 50 First shear web 51 Core Components 52 Skin layer 55 Second shear web 56 Sandwich core material of the second shear web 57 Skin layer of the second shear web 60 Filling rope 61 Top surface of spar cap 62 Reinforcement structure / spar cap 63 Bottom surface of spar cap 64 Pultruded board 66 Pultruded Board Stacking 74 Reinforcement of the end of the structure 76 Root end of reinforcement structure 78 Leading edge of reinforced structure 80 Reinforced structure trailing edge 81 Top surface of pultruded plate 82 Bottom surface of pultruded plate 83 First side surface of pultruded plate 84 Second side surface of pultruded plate 85 Organic alkoxysilane monomer 86 Hydrolyzed organoalkoxysilane monomer 87 Polymeric organoalkoxysilane 88 Hydrogen bond 89 Covalent bond 90 Hydrolysis 91 Condensation / Polymerization 92 Treatment of spar caps with primer composition 93 Heating 94 Spray Gun 95 Heating device 96 Blade Mould 97 Fiber Lamination 98 Molding Cavity 99 Vacuum Bag 100 Resin inlet channel L Length r Distance from hub R rotor radius Se The spanwise extension of the enhanced structure

Claims

1. A method of manufacturing a wind turbine blade shell component (36, 38), the method comprising the following steps: providing a blade mould (96) for the blade shell member, the blade mould comprising a moulding cavity (98), arranging one or more layers of fiber material in the molding cavity to provide a fiber layup (97), providing a prefabricated spar cap member (62), treating a surface (63) of the spar cap member with a primer composition to provide a primed surface, applying heat to the primer treated surface of the spar cap member to provide an activated surface, placing the spar cap member (62) on top of at least a portion of the fiber layup (97) in the mold cavity such that at least a portion of the activated surface of the spar cap member contacts the fiber layup, filling the molding cavity with resin, curing the resin to form the blade shell member, The primer composition comprises a silane compound. 2 . The method according to claim 1 , wherein the silane compound comprises hydroxysilylalkyl methacrylate or a condensation (polymerization) product of hydroxysilylalkyl methacrylate.

3. The method according to claim 1 or 2, wherein the silane compound is a polymer comprising repeating units of formula (I): wherein X is an organic group, preferably a non-hydrolyzable organic group, preferably selected from amino, vinyl, epoxy, methacrylate, thio, alkyl, alkenyl, alkynyl, most preferably methacrylate, and wherein R is a spacer, such as -(CH2) n -, wherein n is 0 to 1000, preferably 1-5, most preferably 3.

4. The method of any one of the preceding claims, wherein the prefabricated spar cap member (62) comprises a vinyl ester resin.

5. The method of any one of the preceding claims, wherein providing the prefabricated spar cap member (62) comprises pultruding a vinyl ester resin impregnated fiber material comprising carbon fibers, and curing the vinyl ester resin to provide the prefabricated spar cap member.

6. A method according to any one of the preceding claims, wherein the step of applying heat to the primer treated surface comprises heating the primer treated surface to a temperature of 80-130°C, preferably 90-120°C.

7. A method according to any one of the preceding claims, wherein the step of applying heat to the primer treated surface comprises heating the primer treated surface to a temperature of 80-130°C, preferably 90-120°C, for a period of 3-60 minutes, preferably 5-30 minutes.

8. A method according to any one of the preceding claims, wherein in the step of infusing the mould cavity with resin, the mould cavity is infused with a polyester resin, preferably an unsaturated polyester resin, to co-infuse the fibre lay-up and the spar cap member.

9. A method according to any one of the preceding claims, wherein the resin used in the step of infusing the moulding cavity with resin is an unsaturated polyester resin, and wherein the step of curing the resin to form the blade shell member comprises a free radical cross-linking reaction between the silane compound or polymer thereof and the unsaturated polyester resin, preferably a free radical cross-linking reaction between the (meth)acrylate groups of the silane compound or polymer thereof of the primer composition and the unsaturated polyester resin.

10. The method according to any one of the preceding claims, wherein the primer composition comprises a carrier solvent, wherein the carrier solvent comprises 1-methoxy-2-propanol and a dicarboxylic acid ester, such as dimethyl glutarate, dimethyl succinate and dimethyl adipate or a mixture thereof, such as a mixture containing 57-67 wt% of dimethyl glutarate, 18-28 wt% of dimethyl succinate and 8-22 wt% of dimethyl adipate.

11. The method according to claim 10, wherein the weight ratio of 1-methoxy-2-propanol to the dicarboxylic acid ester is 1:2 to 2:1, preferably 1:1.2 to 1.2:

1.

12. The method of any one of the preceding claims, wherein the primer composition has a flash point of at least 39°C.

13. A wind turbine blade shell component obtainable by the method according to any one of claims 1-12.

14. Use of a silane-containing primer composition for improving the bond between a first wind turbine blade component (62) and a second wind turbine blade component (97) by treating the surface of the first wind turbine blade component and / or the second wind turbine blade component with the primer composition and thereafter connecting and co-infusing the first wind turbine blade component and the second wind turbine blade component with a resin.

15. The use according to claim 14, further comprising applying heat to the primer treated surface of the first wind turbine blade component and / or the primer treated surface of the second wind turbine blade component to provide an activated surface before joining and co-infusing the first wind turbine blade component and the second wind turbine blade component with resin.

16. Use according to claim 14 or 15, wherein the resin is a polyester resin, such as an unsaturated polyester resin.

17. Use according to any one of claims 14 to 16, wherein the blade components are connected along the primer treated surface.

18. Use according to any one of claims 14 to 17, wherein the second component comprises a vinyl ester resin and / or has been manufactured by infusing a fibre material with a vinyl ester resin.

19. The use according to claim 18, wherein the fiber material comprises carbon fibers.

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