Protective film for blade of wind power generator, blade for wind power generator, and wind power generator

Abstract

To provide a protective film for a blade of a wind power generator that can suppress deterioration in rotation efficiency and emission of wind noise when being affixed to an edge part of a blade.SOLUTION: A protective film 10 for a blade of a wind power generator includes: a protective layer 1; and an adhesion layer 2 disposed on one surface of the protective layer 1, where an end region of the protective layer 1 is configured such that a thickness decreases toward an end side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a protective film for wind turbine blades, a wind turbine blade, and a wind turbine. [Background technology]

[0002] The blades of wind power generation equipment are exposed to ultraviolet rays from sunlight, wind, rain, snow, hail, lightning, seawater, gas, sand, dust, and other debris. The blades of wind power generation equipment may also be affected by collisions with birds, insects, and flying objects. As described above, the blades are exposed to harsh environments, and as a result of long-term use, defects such as damage, deformation, surface contamination, and surface peeling occur. In addition, the blades rotate at high speeds, which increases the possibility of damage, deformation, surface contamination, and surface peeling. These defects lead to a decrease in power generation efficiency. In the worst case, the blades may break or fall.

[0003] In order to protect the blade, a technique has been proposed in which a protective film or protective cover is placed on the surface of the blade, particularly on the edge portion of the blade (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2012 / 102294 [Patent Document 2] Special Publication No. 2018-503775 Summary of the Invention [Problem to be solved by the invention]

[0005] However, applying a protective film to the edge of the blade increases air resistance, which can lead to problems such as reduced rotational efficiency and wind noise.

[0006] The present disclosure has been made in consideration of the above-mentioned situation, and has as its main object to provide a protective film for wind turbine blades that, when attached to the edge portion of the blade, can suppress a decrease in rotational efficiency and the generation of wind noise. [Means for solving the problem]

[0007] One embodiment of the present disclosure provides a protective film for blades of a wind turbine generator, comprising a protective layer and an adhesive layer disposed on one side of the protective layer, and an end region of the protective layer is configured to decrease in thickness toward the end side.

[0008] Another embodiment of the present disclosure provides a protective film for a blade, comprising a protective layer and an adhesive layer disposed on one side of the protective layer, the protective layer being configured such that the thickness of the end portion is thinner than the thickest portion in the central region of the protective layer.

[0009] Another embodiment of the present disclosure provides a protective film for a blade, comprising a protective layer and an adhesive layer disposed on one side of the protective layer, wherein a plurality of protrusions, recesses, convex ridges, or concave grooves are disposed on the surface of the protective layer opposite the adhesive layer side.

[0010] Another embodiment of the present disclosure provides a blade for a wind turbine generator having the above-described blade protective film on a surface thereof.

[0011] Another embodiment of the present disclosure provides a wind turbine generator including the blade described above. Effect of the Invention

[0012] The present disclosure has an effect of providing a protective film for wind turbine blades that can suppress a decrease in rotation efficiency and the generation of wind noise. [Brief description of the drawings]

[0013] [Figure 1]FIG. 2 is a schematic cross-sectional view illustrating a protective film for wind turbine blades in a first embodiment. [Diagram 2] FIG. 1 is a schematic cross-sectional view illustrating a conventional protective film for wind turbine blades. [Diagram 3] 1 is a schematic cross-sectional view illustrating a protective film for wind turbine blades according to the present disclosure. [Figure 4] 1A and 1B are schematic perspective and cross-sectional views illustrating a blade of a wind turbine power generation device according to the present disclosure. [Diagram 5] FIG. 11 is a schematic cross-sectional view illustrating an example of a protective film for wind turbine blades in a second embodiment. [Figure 6] FIG. 11 is a schematic cross-sectional view illustrating another example of the protective film for blades of a wind turbine generator in the second embodiment. [Figure 7] FIG. 11 is a schematic cross-sectional view illustrating a protective film for wind turbine blades in a third embodiment. [Figure 8] 1 is a schematic diagram illustrating a wind power generation device according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following describes the embodiments of the present disclosure with reference to the drawings. However, the present disclosure can be implemented in many different forms, and is not to be construed as being limited to the description of the embodiments exemplified below. In addition, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual form in order to make the explanation clearer, but these are merely examples and should not be used to limit the interpretation of the present disclosure. In addition, in this specification and each figure, elements similar to those described above with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0015] In this specification, when describing a mode in which another component is disposed on a certain component, the term "above" or "below" includes both a case in which another component is disposed directly above or below a certain component so as to be in contact with the component, and a case in which another component is disposed above or below a certain component with another component interposed therebetween, unless otherwise specified. In addition, in this specification, when describing a mode in which another component is disposed on the surface of a certain component, the term "on the surface side" or "on the surface" includes both a case in which another component is disposed directly above or below a certain component so as to be in contact with the component, and a case in which another component is disposed above or below a certain component with another component interposed therebetween, unless otherwise specified.

[0016] In this specification, the term "film" also includes a member called a "sheet."

[0017] The protective film for wind turbine blades, the wind turbine blades, and the wind turbine according to the present disclosure will be described in detail below.

[0018] A.Protective film for wind turbine blades The protective film for wind turbine blades of the present disclosure has three embodiments, each of which will be described below. In this specification, the "protective film for wind turbine blades" may be simply referred to as the "protective film".

[0019] A-1. First embodiment A first embodiment of the protective film for wind power generation device blades of the present disclosure has a protective layer and an adhesive layer arranged on one side of the protective layer, and the end region of the protective layer is configured to decrease in thickness toward the end side.

[0020] Fig. 1 is a schematic cross-sectional view illustrating a protective film in this embodiment. The protective film 10 in Fig. 1 has a protective layer 1 and an adhesive layer 2 disposed on one surface of the protective layer 1. An end region E of the protective layer 1 is configured so that the thickness decreases toward the end e1 side.

[0021] FIG. 2 shows a state where a conventional protective film 10 is arranged on the surface of a blade 20. As shown in FIG. 2, an end e1 of the conventional protective film 10 is formed at a substantially right angle. Therefore, the thickness of the protective film 10 arranged on the surface of the blade 20 is abruptly reduced at the end e1, forming a step. When air W moving in the direction of the arrow from the edge side on the left side of FIG. 2 comes into contact with such a protective film 10, a turbulent flow V called a Karman vortex or the like is generated behind the end e1, resulting in a problem of increased air resistance.

[0022] In this embodiment, as described above, the end region E of the protective layer 1 is configured so that the thickness gradually decreases toward the end e1 side, making it possible to suppress the generation of turbulence V as described above and reducing air resistance.

[0023] 1, the protective film of this embodiment can eliminate or reduce the step at the end e1 of the protective film 10. Therefore, when some force is applied to the end e1, it is possible to prevent the protective film 10 from peeling off. This reduces the need to use a peel prevention tape such as a silicone seal placed over the end e1 to prevent peeling off at the end e1.

[0024] 1.Protective layer (1) Shape of the protective layer The protective layer in this embodiment has an end region E where the thickness decreases toward the end. Here, the end region E of the protective layer 1 in this embodiment is a region on the end side of the protective film 10, and refers to the distance from the position e2 where the thickness of the protective layer 1 starts to decrease toward the end e1 (hereinafter, may be referred to as the decrease start position) to the end e1.

[0025] In this embodiment, the lower limit of the distance of the edge region E is preferably 1 cm or more, more preferably 3 cm or more, and even more preferably 5 cm or more, while the upper limit of the distance of the edge region is preferably 100 cm or less, more preferably 90 cm or less, and even more preferably 80 cm or less.

[0026] The shape of the protective layer 1 in the end region E is not particularly limited as long as the thickness decreases from the decrease start position e2 toward the end e1, but examples of the shape include a shape in which the thickness decreases linearly as shown in Fig. 1, a shape in which the thickness decreases stepwise, and a shape in which the thickness decreases parabolically. In this embodiment, a shape in which the thickness decreases linearly is preferable, because this has a high effect of suppressing the generation of turbulence as described above.

[0027] The lower limit of the thickness of the protective layer 1 at the decrease start position e2 is preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more. On the other hand, the upper limit of the thickness is preferably 1000 μm or less, more preferably 900 μm or less, and even more preferably 800 μm or less.

[0028] Furthermore, the thickness of the protective layer 1 at the end e1 may be 800 μm or less, and may particularly be 500 μm or less, but is particularly preferably 0 μm.

[0029] The film thickness in the region other than the end region of the protective layer 1 (hereinafter sometimes referred to as the central region) is usually the same as the thickness at the decrease start position e2, but is not particularly limited to this, and may be configured so that the film thickness is thicker in the central portion, as described in the second embodiment described later.

[0030] (2) Physical properties of the protective layer (a) Tensile modulus In this embodiment, the tensile modulus of the protective layer is 35 MPa or less, may be 30 MPa or less, may be 20 MPa or less, or may be 15 MPa or less. When the tensile modulus of the protective layer is within the above range, the protective layer tends to be soft, stretchable, and difficult to deform. Therefore, when wind, rain, snow, hail, hail, seawater, sand, dust, dirt, birds, insects, flying objects, etc. collide with the surface of the blade having the protective film, the protective layer of the protective film can absorb the impact. Therefore, the occurrence of erosion can be suppressed. In addition, the conformability to the curved surface of the blade can be improved. On the other hand, the tensile modulus of the protective layer is 5 MPa or more, may be 7 MPa or more, or may be 10 MPa or more. If the tensile modulus of the protective layer is too low, the protective layer may become too soft, which may reduce the erosion resistance or make it difficult to handle the protective film. Specifically, the tensile modulus of the protective layer is 5 MPa or more and 35 MPa or less, may be 5 MPa or more and 30 MPa or less, may be 7 MPa or more and 20 MPa or less, or may be 10 MPa or more and 15 MPa or less.

[0031] The tensile modulus is measured using a tensile tester in accordance with ISO 527-3:2018. The tensile modulus is the slope of the stress-strain curve calculated by the least squares method between the two points of 5% strain and 10% strain. The specific measurement conditions are shown below.

[0032] <Measurement conditions> Test piece: rectangular - Test piece size: width 10mm, length 120mm ·Distance between gauge lines: 25mm Pulling speed: 100mm / min Test conditions: Temperature 25℃, humidity 50%RH Number of test pieces: Measurement is performed on three test pieces, and the arithmetic average value is used.

[0033] When measuring the tensile modulus of the protective layer, the adhesive layer is removed from the protective film, and the protective layer is taken out. As a method for removing the adhesive layer, a method of dissolving the adhesive layer with a solvent can be used. As the solvent, the solvent contained in the adhesive composition used to form the adhesive layer can be used.

[0034] (b) Tensile breaking stress In this embodiment, the tensile breaking stress of the protective layer is, for example, 5 MPa or more, may be 7 MPa or more, or may be 10 MPa or more. The tensile breaking stress of the protective layer is in the above range, so that durability can be improved. On the other hand, the tensile breaking stress of the protective layer is, for example, 35 MPa or less, may be 30 MPa or less, or may be 20 MPa or less. If the tensile breaking stress of the protective layer is too large, the protective film becomes difficult to stretch, and the ability to follow the curved surface of the blade may decrease. Specifically, the tensile breaking stress of the protective layer is 5 MPa or more and 35 MPa or less, may be 7 MPa or more and 30 MPa or less, or may be 10 MPa or more and 20 MPa or less.

[0035] The tensile stress at break is measured using a tensile tester in accordance with ISO 527-3:2018. The tensile stress at break is the stress at which the test piece breaks. The tensile test for measuring the tensile stress at break is the same as the tensile test for measuring the tensile modulus of elasticity described above.

[0036] (c) Tensile elongation at break In this embodiment, the tensile elongation at break of the protective layer is, for example, preferably 800% or more, may be 1000% or more, or may be 1200% or more. When the tensile elongation at break of the protective layer is in the above range, durability can be improved. On the other hand, the upper limit of the tensile elongation at break of the protective layer is not particularly limited, but may be, for example, 3500% or less, 3000% or less, or 2500% or less. Specifically, the tensile elongation at break of the protective layer is 800% or more and 3500% or less, 1000% or more and 3000% or less, or 1200% or more and 2500% or less.

[0037] The tensile elongation at break is measured using a tensile tester in accordance with ISO 527-3:2018. The tensile elongation at break is the elongation at break of the test piece. The tensile test for measuring the tensile elongation at break is the same as the tensile test for measuring the tensile modulus described above.

[0038] (d) Type A durometer hardness In this embodiment, the type A durometer hardness of the protective layer is preferably, for example, 95 or less, may be 90 or less, or may be 85 or less. When the type A durometer hardness of the protective layer is within the above range, the protective layer tends to be relatively soft. Therefore, the protective layer of the protective film can absorb the impact caused by the collision with the blade, so that the occurrence of erosion can be suppressed. In addition, the conformability to the curved surface of the blade can be improved. On the other hand, the type A durometer hardness of the protective layer is, for example, 60 or more, may be 65 or more, or may be 70 or more. If the durometer A hardness of the protective layer is too low, the protective layer may become too soft, and the erosion resistance may decrease, or the handling of the protective film may become difficult. Specifically, the type A durometer hardness of the protective layer is 60 or more and 95 or less, may be 65 or more and 90 or less, or may be 70 or more and 85 or less.

[0039] Type A durometer hardness is measured using a hardness tester in accordance with JIS K6253-3:2012. However, when stacking test pieces for measurement, the number of test pieces stacked is not limited. For example, when the thickness of the protective layer is 300 μm, 20 test pieces are stacked. The specific measurement conditions are shown below.

[0040] <Measurement conditions> Test piece thickness: 6mm Test conditions: 23℃, 50% RH Measurement time: 3 seconds

[0041] (e) Water vapor permeability In this embodiment, the water vapor permeability of the protective layer is, for example, 15.0 g / (m 2 24h) or less is preferable, and 10.0g / (m 224h) or less is more preferable, and 5.0g / (m 2 24h) or less is more preferable, and 4.0g / (m 2 24h) or less, and 3.0g / (m 2 The water vapor permeability of the protective layer may be within the above range, thereby preventing moisture from penetrating into the blade. This prevents corrosion and damage to the blade and deterioration of the insulation of the electrical system. On the other hand, there is no particular lower limit for the water vapor permeability of the protective layer.

[0042] The water vapor permeability is measured using a water vapor permeability measuring device in accordance with JIS K7129-2:2019. For example, the water vapor permeability measuring device "PERMATRAN-w 3 / 33" manufactured by MOCON is used. First, a test piece of a predetermined size is cut out from the protective layer. Next, the test piece is mounted between the upper and lower chambers of the water vapor permeability measuring device. At this time, if the protective layer is multi-layered, the test piece is mounted in the water vapor permeability measuring device so that the surface of the protective layer opposite the adhesive layer is the high humidity side (water vapor supply side). Next, the measurement is performed under conditions of a temperature of 40 ° C. and 90% RH. Measurement is performed with three test pieces, and the arithmetic average value is adopted. When measuring the water vapor permeability of the protective layer, the adhesive layer is removed from the protective film and the protective layer is taken out. The method of removing the adhesive layer is as described above.

[0043] In general, polyolefin resins tend to have lower water vapor permeability than polyurethane resins.

[0044] (f) Total light transmittance In this embodiment, the total light transmittance of the protective layer is, for example, preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more. As described above, it is important to inspect the blades of the wind power generation device periodically and, if necessary, perform maintenance such as repair. If the total light transmittance is within the above range, the transparency is good. Therefore, the surface of the blade can be visually confirmed through the protective film, so that the time to replace the protective film can be easily determined.

[0045] Total light transmittance is measured in accordance with ISO 13468-1:1996.

[0046] (g) Water contact angle In this embodiment, the protective layer is preferably hydrophobic. The adhesion of moisture to the blade can be suppressed. This can suppress condensation, rain, snow, and ice caused by temperature changes on the blade. This can suppress a decrease in power generation efficiency. In addition, the infiltration of moisture into the inside of the blade can be suppressed. This can suppress corrosion and damage of the blade and a decrease in insulation of the electrical system.

[0047] (h) Gel fraction When the protective layer contains a crosslinked polyolefin resin or a non-crosslinked polyolefin resin as described below, the degree of crosslinking can be represented by the gel fraction.

[0048] When the protective layer contains a non-crosslinked polyolefin resin, the gel fraction of the protective layer is usually 5% or less, and preferably 0%.

[0049] On the other hand, when the protective layer contains a crosslinked polyolefin resin, the gel fraction of the protective layer is, for example, preferably 30% or more, more preferably 40% or more. In this case, the gel fraction of the protective layer is preferably 90% or less, more preferably 80% or less. Specifically, the gel fraction of the protective layer is preferably 30% or more and 90% or less, more preferably 40% or more and 80% or less.

[0050] In this specification, the gel fraction (%) is measured by the following method. First, 1.0 g of the protective layer is placed in a resin mesh and extracted with 110°C xylene for 24 hours. Next, the protective layer is taken out together with the resin mesh, dried, and then weighed. Next, the mass % of the residual insoluble matter is measured by comparing the mass before and after extraction. The mass % of the residual insoluble matter is then defined as the gel fraction.

[0051] The gel fraction of 0% means that the residual insoluble matter is substantially 0 and the crosslinking reaction of the resin composition has not substantially started. More specifically, the gel fraction of 0% means that the residual insoluble matter does not exist at all and that the mass % of the residual insoluble matter measured by a precision balance is less than 0.05 mass %.

[0052] The residual insoluble matter does not include pigment components other than the resin components. When the residual insoluble matter is found to contain impurities other than the resin components in the above test, the gel fraction that should be obtained for the residual insoluble matter derived from the resin components excluding these impurities can be calculated, for example, by separately measuring the contents of these impurities in the resin components in advance.

[0053] (3) Protective layer material The material for the protective layer in this embodiment is not particularly limited as long as it is a material that is usually used in a protective film for a blade, and examples thereof include polyurethane-based resins and polyolefin-based resins. In the present embodiment, among these, polyolefin-based resins are preferred, because polyolefin-based resins have high durability and therefore can suppress deterioration of the performance of the protective film due to deterioration over time. (a) Polyolefin resin The polyolefin-based resin may be obtained by polymerizing only olefins, or may be obtained by copolymerizing olefins and monomers other than olefins. That is, the polyolefin-based resin may be composed of only olefins, or may be composed of olefins and monomers other than olefins. Among them, the polyolefin-based resin is preferably composed of only olefins.

[0054] Examples of polyolefin resins include polyethylene resins and polypropylene resins. Among them, polyethylene resins are preferred.

[0055] The polyethylene resin may be a homopolymer of ethylene, a copolymer of ethylene and an α-olefin, or a copolymer of ethylene and a monomer other than an olefin.

[0056] In the copolymer of ethylene and α-olefin, the α-olefin is preferably an α-olefin having 3 to 12 carbon atoms. Specific examples include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, and 4,4-dimethylpentene-1. The α-olefin may be used alone or in combination of two or more. Among them, unbranched α-olefins are preferred, and unbranched α-olefins having 3 to 8 carbon atoms are more preferred. Specific examples include 1-propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. The α-olefin having 3 to 8 carbon atoms can impart good flexibility and good strength.

[0057] Specific examples of copolymers of ethylene and α-olefins include ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, and ethylene-4-methyl-pentene-1 copolymers.

[0058] A specific example of a copolymer of ethylene and a monomer other than an olefin is an ethylene-vinyl acetate copolymer.

[0059] Examples of polyethylene resins include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene linear low density polyethylene (M-LLDPE), and very low density polyethylene (VLDPE). The polyethylene resins may be used alone or in combination of two or more.

[0060] Among them, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene linear low density polyethylene (M-LLDPE), and very low density polyethylene (VLDPE) are preferred. They have good flexibility, transparency, and processability. Since the protective layer can be given good flexibility, the protective layer of the protective film can absorb the impact caused by collision with the blade, and the occurrence of erosion can be suppressed. In addition, the ability to conform to the curved surface of the blade can be improved.

[0061] Metallocene linear low density polyethylene (M-LLDPE) is synthesized using a metallocene catalyst, which is a single-site catalyst. In such polyethylene resins, there is little branching of the side chains and the distribution of the comonomers is uniform. This allows for a narrow molecular weight distribution and low density, which gives flexibility and strength. In addition, the crystallinity distribution is narrow and the crystal size is uniform, so not only are there no crystals with large sizes, but the low density also means that the crystallinity itself is low. This gives the resin excellent transparency.

[0062] The density of the polyethylene resin is not particularly limited. The density of the polyethylene resin is, for example, 0.950 g / cm 3 Less than or equal to 0.930 g / cm 3 or less, 0.925 g / cm 3 or less, 0.920 g / cm 3 or less. When the density of the polyethylene resin is in the above range, flexibility, transparency, and processability can be improved. Since the protective layer can be given good flexibility, the protective layer of the protective film can absorb the impact caused by collision with the blade, and the occurrence of erosion can be suppressed. In addition, the ability to conform to the curved surface of the blade can be improved. In addition, when the density of the polyethylene resin is in the above range, the unit weight of the protective layer can be reduced, and the weight of the protective film can be reduced. On the other hand, the density of the polyethylene resin is, for example, 0.850 g / cm 3 More than 0.870g / cm 3 That is, the density of the polyethylene resin may be, for example, 0.850 g / cm 3More than 0.950g / cm 3 Less than or equal to 0.850 g / cm 3 More than 0.930g / cm 3 or less, 0.870 g / cm 3 More than 0.925g / cm 3 or less, 0.870 g / cm 3 More than 0.920g / cm 3 It may be the following.

[0063] The density of polyethylene resins is measured by the pycnometer method in accordance with ISO 1183:2019.

[0064] The melting point of the polyethylene resin is not particularly limited. The melting point of the polyethylene resin is, for example, 130°C or less. With polyolefin resins, the lower the melting point, the softer they tend to be. Therefore, if the melting point is within the above range, the protective layer can be given good flexibility, so that the protective layer of the protective film can absorb the impact caused by the collision with the blade, and the occurrence of erosion can be suppressed. In addition, the ability to follow the curved surface of the blade can be improved. On the other hand, the melting point of the polyethylene resin is, for example, 50°C or more, and may be 60°C or more. If the melting point is too low, the heat resistance may be reduced.

[0065] The melting point of the resin is measured by a differential scanning calorimeter (DSC) in accordance with ISO 3146: 2000. If there are two or more melting point peaks, the higher temperature is taken as the melting point.

[0066] The melt mass flow rate (MFR) of the polyethylene resin at a temperature of 190°C is, for example, preferably 0.1 g / 10 min or more and 30 g / 10 min or less, more preferably 0.1 g / 10 min or more and 25 g / 10 min or less, and even more preferably 0.1 g / 10 min or more and 20 g / 10 min or less. By having the MFR of the polyethylene resin be equal to or less than a predetermined value, the strength can be improved. In addition, by having the MFR of the polyethylene resin be within the above range, the film-forming property and flexibility can be improved.

[0067] The melt mass flow rate (MFR) of polyethylene resins is measured in accordance with ISO 1133-1:2011. The measurement conditions are Method A, temperature 190°C, and load 2.16 kg.

[0068] It is preferable that the polyethylene resin does not contain an ester bond, since this allows for excellent hydrolysis resistance to be obtained.

[0069] The polyolefin resin may be a crosslinked polyolefin resin or a non-crosslinked polyolefin resin, and the polyethylene resin may be a crosslinked polyethylene resin or a non-crosslinked polyethylene resin.

[0070] The crosslinked polyolefin resin refers to a crosslinked polyolefin resin, i.e., a polyolefin resin having crosslinked bonds, whereas the non-crosslinked polyolefin resin refers to a non-crosslinked polyolefin resin.

[0071] The cross-linked polyethylene resin refers to a polyethylene resin that is cross-linked, that is, a polyethylene resin having cross-linked bonds, whereas the non-cross-linked polyethylene resin refers to a polyethylene resin that is not cross-linked.

[0072] As a crosslinking method for crosslinking the polyolefin resin, a general crosslinking method can be applied, for example, a crosslinking method using a crosslinking agent, a silane crosslinking method using silanol condensation, and a crosslinking method using ionizing radiation. Among them, a crosslinking method using a crosslinking agent is preferable.

[0073] As the crosslinking agent, a general crosslinking agent can be used, for example, organic peroxides can be mentioned. As the organic peroxides, for example, peroxycarbonates, peroxyketals, and dialkyl peroxides can be mentioned. As the peroxycarbonates, for example, t-amyl-peroxy-2-ethylhexyl carbonate, t-butylperoxy 2-ethylhexyl carbonate can be mentioned. As the peroxyketals, for example, n-butyl 4,4-di(t-butylperoxy)valerate, ethyl 3,3-di(t-butylperoxy)butyrate, and 2,2-di(t-butylperoxy)butane can be mentioned. As the dialkyl peroxides, for example, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-di(t-peroxy)hexyne-3 can be mentioned. The crosslinking agent may be used alone or in combination of two or more kinds.

[0074] In the resin composition used to form the protective layer, the content of the crosslinking agent is appropriately selected depending on the desired degree of crosslinking, etc.

[0075] In addition, in the crosslinking method using a crosslinking agent, a crosslinking assistant may be used. By using the crosslinking assistant, it is possible to promote an appropriate crosslinking reaction. Furthermore, the crosslinking assistant reduces the crystallinity of the polyolefin resin, so that the transparency can be maintained. As the crosslinking assistant, a general crosslinking assistant can be used, and for example, a polyfunctional monomer having a polymerizable functional group can be mentioned.

[0076] Among them, from the viewpoint of improving reactivity, the crosslinking auxiliary is preferably a nurate ring-containing compound having two or more polymerizable functional groups in one molecule.

[0077] In the crosslinking aid, the number of polymerizable functional groups is preferably 2 to 6 in one molecule, more preferably 2 to 3 in one molecule. If the number of polymerizable functional groups is too small, the crosslinking density may not be increased sufficiently. On the other hand, if the number of polymerizable functional groups is too large, the physical properties of the protective layer may be adversely affected, such as the protective layer becoming brittle after crosslinking treatment.

[0078] The polymerizable functional group is not particularly limited as long as it can react with the polyolefin resin, which is the base resin, and can impart a crosslinked structure, but among them, a group having a carbon-carbon double bond, an epoxy group, etc. Examples of the group having a carbon-carbon double bond include a vinyl group, a (meth)acryloyl group, a (meth)acryloyloxy group, and an allyl group.

[0079] Examples of the crosslinking aid include polyallyl compounds, poly(meth)acryloxy compounds, and epoxy compounds. Examples of the polyallyl compounds include triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate. Examples of the poly(meth)acryloxy compounds include trimethylolpropane trimethacrylate (TMPT), trimethylolpropane triacrylate (TMPTA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and 1,9-nonanediol diacrylate. Examples of the epoxy compounds include epoxy compounds containing a double bond and an epoxy group, and epoxy compounds containing two or more epoxy groups. Examples of the epoxy compounds containing a double bond and an epoxy group include glycidyl methacrylate and 4-hydroxybutyl acrylate glycidyl ether. Examples of epoxy compounds containing two or more epoxy groups include 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, and trimethylolpropane polyglycidyl ether. The crosslinking aid may be used alone or in combination of two or more.

[0080] Among them, it is preferable to use triallyl isocyanurate (TAIC) as a crosslinking aid. Triallyl isocyanurate (TAIC) has good compatibility with linear low-density polyethylene, and can reduce crystallinity by crosslinking and maintain transparency. Furthermore, triallyl isocyanurate (TAIC) can impart flexibility at low temperatures to the protective layer.

[0081] In the resin composition used to form the protective layer, the content of the crosslinking aid is appropriately selected depending on the desired degree of crosslinking, etc.

[0082] The content of the polyolefin resin is, for example, preferably 90 parts by mass or more, and more preferably 95 parts by mass or more, relative to 100 parts by mass of all resin components contained in the protective layer, which can improve transparency and flexibility.

[0083] The ratio of each resin component contained in the protective layer is analyzed from the peak ratio detected by differential scanning calorimetry (DSC).

[0084] (b) Additives The protective layer may contain additives as necessary. Examples of additives include light stabilizers, ultraviolet absorbers, antioxidants, heat stabilizers, nucleating agents, dispersants, leveling agents, plasticizers, defoamers, flame retardants, and fillers. Of these, the protective layer preferably contains a weathering agent. Examples of weathering agents include light stabilizers, ultraviolet absorbers, and antioxidants.

[0085] Examples of light stabilizers include hindered amine light stabilizers (HALS). Hindered amine light stabilizers are broadly divided into three types according to the bond partner of the nitrogen atom in the piperidine skeleton: NH type (hydrogen bonded to the nitrogen atom), NR type (an alkyl group (R) bonded to the nitrogen atom), and N-OR type (an alkoxy group (OR) bonded to the nitrogen atom). Among these, N-OR type hindered amine light stabilizers are preferred. The N-OR type is faster at capturing radicals than the NH type and NR type. Furthermore, the N-OR type low molecular weight HALS, which migrates to the surface faster than the polymer HALS, has a higher molecular weight than the NH type and N-CH 3 It captures radicals for a shorter period of time than HALS, and therefore can suppress deterioration of the protective layer.

[0086] The weather resistant agent such as the light stabilizer, the ultraviolet absorber and the antioxidant may be added to the resin composition as a weather resistant master batch dispersed in the resin. The weather resistant master batch may be prepared appropriately or may be a commercially available product. The resin used in the weather resistant master batch may be the polyolefin resin described above or other resins.

[0087] The content of the additive in the protective layer is, for example, 5% by mass or less.

[0088] (4) Layer structure of protective layer The protective layer may have at least a polyolefin resin film containing a polyolefin resin. The protective layer may be a single layer composed of a polyolefin resin film, or may be a multilayer having a polyolefin resin film. When the protective layer has a plurality of polyolefin resin films, the polyolefin resins contained in each polyolefin resin film may be the same or different. In addition, in the case of a multilayer, the protective layer may have a polyolefin resin film and a surface film that is disposed on the surface of the polyolefin resin film opposite to the adhesive layer and contains a cured product of an electron beam curable resin composition.

[0089] (a) Surface film 3, the protective layer 1 may have a polyolefin resin film 1a containing a polyolefin resin, and a surface film 1b containing a cured product of an electron beam curable resin composition and disposed on the surface of the polyolefin resin film 1a opposite to the adhesive layer 2. The durability of the protective layer can be further improved by having the surface film.

[0090] The electron beam curable resin composition contains at least an electron beam curable resin, which may be appropriately selected from a polymerizable monomer, a polymerizable oligomer, and a polymerizable prepolymer.

[0091] The surface film may contain an ultraviolet absorbing agent. As described later, when no primer film is arranged between the polyolefin resin film and the surface film, the surface film preferably contains an ultraviolet absorbing agent. On the other hand, when a primer film is arranged between the polyolefin resin film and the surface film, at least one of the surface film and the primer film preferably contains an ultraviolet absorbing agent.

[0092] The ultraviolet absorbing agent may be either an inorganic ultraviolet absorbing agent or an organic ultraviolet absorbing agent.

[0093] As the inorganic ultraviolet absorbing agent, for example, titanium oxide, cerium oxide, and zinc oxide having an average particle size of about 5 nm or more and 120 nm or less are preferable.

[0094] Examples of organic ultraviolet absorbers include benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, benzophenone ultraviolet absorbers, salicylate ultraviolet absorbers, and acrylonitrile ultraviolet absorbers. Examples of benzotriazole ultraviolet absorbers include 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-amylphenyl)benzotriazole, and 3-[3-(benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionic acid ester of polyethylene glycol. Examples of triazine-based ultraviolet absorbers include 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]phenol, 1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 1,3,5-tri[[3,5-bis-(1,1-dimethylethyl)-4-hydroxyphenyl]methyl].

[0095] The surface film may contain additives other than the ultraviolet absorber, if necessary.

[0096] In order to impart weather resistance to the surface film, a light stabilizer may be used in combination with the ultraviolet absorber. Examples of light stabilizers include hindered amine light stabilizers. Specific examples include 2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2'-n-butylmalonic acid bis(1,2,2,6,6-pentamethyl-4-piperidyl), bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, and tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate.

[0097] Examples of other additives include abrasion resistance improvers, polymerization inhibitors, crosslinking agents, infrared absorbing agents, antistatic agents, adhesion improvers, leveling agents, thixotropy imparting agents, coupling agents, plasticizers, defoamers, fillers, solvents, and colorants.

[0098] (b) Primer film The protective layer may have a primer film between the polyolefin resin film and the surface film, which can improve the adhesion between the polyolefin resin film and the surface film.

[0099] (5) Method for forming protective layer The method for forming the protective layer in this embodiment is not particularly limited as long as it is a method capable of forming the end region whose thickness decreases in the end direction as described above. Specifically, for example, in the case of extrusion molding, it is possible to form a protective layer having the end region by adjusting the shape of the die. Moreover, after forming a sheet-like protective layer, the end portion may be mechanically processed, such as by polishing, to form an end region.

[0100] The surface of the protective layer on the adhesive layer side may be subjected to an easy-adhesion treatment if necessary. This can improve the adhesion to the adhesive layer. In addition, when the protective layer is multi-layered, the surface of the polyolefin resin film opposite to the adhesive layer may be subjected to an easy-adhesion treatment if necessary. This can improve the adhesion between the polyolefin resin film and the surface film or primer film. Examples of the easy-adhesion treatment include corona discharge treatment, plasma treatment, and ozone treatment.

[0101] 2.Adhesive layer The adhesive layer in this embodiment is a member for attaching the protective film to the blades of the wind turbine generator.

[0102] The adhesive layer is not particularly limited as long as it can attach the protective film to the blade, and is appropriately selected according to the material of the blade. A general adhesive can be used for the adhesive layer. For example, an ultraviolet curing adhesive, a two-component curing adhesive, and a pressure-sensitive adhesive can be mentioned. The ultraviolet curing adhesive and the two-component curing adhesive can increase the adhesive strength. In addition, the pressure-sensitive adhesive has good workability.

[0103] Examples of pressure-sensitive adhesives include acrylic adhesives, urethane adhesives, and silicone adhesives. Among them, acrylic adhesives are preferred. Acrylic adhesives are excellent in transparency, weather resistance, heat resistance, and the like.

[0104] The thickness of the adhesive layer is not particularly limited as long as it can bond the protective film and the blade, and is appropriately selected according to the application. The thickness of the adhesive layer is, for example, 25 μm or more, may be 25 μm or more, or may be 30 μm or more. The thickness of the adhesive layer is, for example, 120 μm or less, may be 90 μm or less, or may be 80 μm or less. That is, the thickness of the adhesive layer is, for example, 25 μm or more and 120 μm or less, may be 25 μm or more and 90 μm or less, or may be 30 μm or more and 80 μm or less.

[0105] 3. Other configurations The protective film in this embodiment may have other configurations depending on the application.

[0106] The protective film in this embodiment may have a separator on the surface of the adhesive layer opposite to the protective layer.

[0107] 4.Properties of protective film (1) Adhesive strength In the protective film of this embodiment, the adhesive strength to the SUS plate is, for example, preferably 3N / 10mm or more, may be 7N / 10mm or more, or may be 10N / 10mm or more. When the adhesive strength is in the above range, durability can be improved. On the other hand, the upper limit of the adhesive strength to the SUS plate is not particularly limited, but is, for example, preferably 30N / 10mm or less, may be 25N / 10mm or less, or may be 20N / 10mm or less. If the adhesive strength is too large, the workability at the time of replacing the protective film may be deteriorated. Specifically, the adhesive strength to the SUS plate is preferably 3N / 10mm or more and 30N / 10mm or less, may be 7N / 10mm or more and 25N / 10mm or less, or may be 10N / 10mm or more and 20N / 10mm or less.

[0108] The adhesive strength to the SUS plate is measured in accordance with JIS Z0237:2009, Method 6. The specific measurement conditions are shown below. For example, the tensile tester used is "Tensilon RTF1150" manufactured by A&D Co., Ltd. The SUS plate used is a steel plate of SUS304 with a surface finish of BA.

[0109] <Measurement conditions> Tape width: 10mm Peeling speed: 300mm / min Peel angle: 90 degrees Test conditions: 23℃, 50%RH Number of tests: Measurements are performed on three test pieces, and the arithmetic average value is used.

[0110] In the protective film of this embodiment, the adhesive strength to the fluororesin layer is, for example, preferably 2.5 N / 10 mm or more, may be 4 N / 10 mm or more, or may be 5 N / 10 mm or more. The adhesive strength in the above range can improve durability. On the other hand, the upper limit of the adhesive strength to the fluororesin layer is not particularly limited, but is, for example, preferably 30 N / 10 mm or less, may be 25 N / 10 mm or less, or may be 20 N / 10 mm or less. If the adhesive strength is too large, the workability at the time of replacing the protective film may be deteriorated. Specifically, the adhesive strength to the fluororesin layer is preferably 2.5 N / 10 mm or more and 30 N / 10 mm or less, may be 4 N / 10 mm or more and 25 N / 10 mm or less, or may be 5 N / 10 mm or more and 20 N / 10 mm or less.

[0111] The adhesive strength to the fluororesin layer is measured in accordance with Method 6 of JIS Z0237:2009. The specific measurement conditions are the same as those for measuring the adhesive strength to the SUS plate. For example, a tensile tester such as "Tensilon RTF1150" manufactured by A&D Co., Ltd. is used. Instead of the SUS plate, a test plate prepared by the following method is used. A fluororesin paint ("Wind Hullo Topcoat F" manufactured by Nippon Tokushu Toryo Co., Ltd.) is applied to one side of the SUS substrate by the roller method to form a fluororesin layer with a thickness of 100 μm to 150 μm, which is used as the test plate.

[0112] In the protective film of this embodiment, the adhesive strength (N / 10 mm) to the fluororesin layer is preferably equal to or greater than the tensile load (N) at 10% elongation of the protective layer, thereby improving durability.

[0113] The tensile load of the protective layer at 10% elongation is measured using a tensile tester in accordance with ISO 527-3:2018. The measurement conditions are the same as those for the tensile modulus measurement described above. For example, the tensile tester used is "Tensilon RTF1150" manufactured by A&D Co., Ltd.

[0114] (2) Total light transmittance In this embodiment, the total light transmittance of the protective film is, for example, preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more. If the total light transmittance is within the above range, the transparency is good. Therefore, the surface of the blade can be visually confirmed through the protective film, so that the time to replace the protective film can be easily determined. The total light transmittance is measured in accordance with ISO 13468-1:1996.

[0115] (3) Erosion depth In this embodiment, the erosion depth from the surface of the protective film on the protective layer side when the amount of projected particles is 40 g, obtained by a microslurry jet erosion (MSE) test, is preferably, for example, 30 μm or less, may be 25 μm or less, or may be 20 μm or less. If the erosion depth is within the above range, durability can be improved. The lower limit of the erosion depth is not particularly limited.

[0116] The erosion depth is a value obtained by a micro-slurry jet erosion (MSE) test. In the MSE test, a certain amount of particles is projected onto the same point on the sample surface, and the erosion depth is measured repeatedly to obtain the relationship between the amount of projected particles and the erosion depth.

[0117] The erosion depth is measured using the MSE tester "MSE-A" manufactured by Palmeso. The measurement conditions are as follows. The surface of the protective film facing the protective layer is used as the sample surface, and measurements are taken at three points, and the arithmetic average value is used.

[0118] <Measurement conditions> Particles: Polygonal alumina (average particle size 1.2 μm) ·Projection particle speed: 360km / hour Test conditions: 25℃, 50% RH

[0119] 5.Applications The protective film of this embodiment is attached to the surface of the blade of a wind power generator. For example, as shown in Figures 4(a) and 4(b), the protective film 10 is preferably disposed on the tip 22 of the leading edge 21 of the blade 20, but may be disposed on the entire leading edge 21, or may be disposed on the blade portion 23 other than the leading edge 21.

[0120] In the present embodiment, the protective film is preferably arranged such that the end region is disposed on a side along the leading edge 21, rather than on a side that intersects with the leading edge 21. This makes it possible to reduce air resistance and improve rotation efficiency.

[0121] A-2. Second embodiment A second embodiment of the protective film for wind power generation device blades of this embodiment has a protective layer and an adhesive layer arranged on one side of the protective layer, and the protective layer is configured so that the thickness of the end portion is thinner than the thickest portion in the central region of the protective layer.

[0122] Fig. 5 is a schematic cross-sectional view illustrating a protective film in this embodiment. The protective film 10 in Fig. 5 has a protective layer 1 and an adhesive layer 2 disposed on one surface of the protective layer 1. In the example shown in Fig. 5, a protrusion 3 is formed in a central region C of the protective layer, and the thickness of the thickest part c1 of the protrusion 3 is configured to be thicker than the thickness of the end part e1.

[0123] Fig. 6 is a schematic cross-sectional view showing another example of the protective film in this embodiment. The protective film 10 shown in Fig. 6 has a protective layer 1 and an adhesive layer 2 disposed on one surface of the protective layer 1. In the example shown in Fig. 6, the cross-sectional shape of the protective layer 1 is substantially triangular, and the thickness of the thickest part c1, which is the apex of the substantially triangle in the central region C, is configured to be thicker than the thickness of the end part e1.

[0124] Usually, the leading edge 21 (see FIG. 4) of the blade 20 of a wind power generator is most susceptible to collisions with birds, insects, flying objects, etc. Therefore, since this part needs to be protected intensively, it is preferable that the protective sheet for this part is thicker. However, if a protective layer is formed with the necessary thickness for the leading edge 21, the end of the protective layer will also be thick. As a result, as explained in the first embodiment above, turbulence will occur at the end, increasing air resistance, reducing rotation efficiency, and generating wind noise.

[0125] In the protective film of this embodiment, as described above, the protective layer is configured so that the thickness at the ends is thinner than the thickest part in the central region of the protective layer. Therefore, by positioning the protective film so that the central region of the protective layer forms the leading edge of the blade, it is possible to reduce air resistance due to turbulence generated at the ends of the protective film while adequately protecting the leading edge.

[0126] 1.Protective layer (1) Shape of the protective layer The protective layer in this embodiment is configured so that the thickness of the end portion is thinner than the thickest portion in the central region of the protective layer. Here, the central region C of the protective layer 1 in this embodiment refers to the region on the central side of the protective film 10, which is disposed so as to face the leading edge portion when the protective film 10 is disposed on the blade.

[0127] In this embodiment, the lower limit of the distance from the end e1 of the protective layer 1 to the central region C is preferably 1 cm or more, more preferably 3 cm or more, and even more preferably 5 cm or more. On the other hand, the upper limit of the distance from the end e1 of the protective layer 1 to the central region C is preferably 100 cm or less, more preferably 90 cm or less, and even more preferably 80 cm or less.

[0128] The shape of the protective layer in this embodiment is not particularly limited, but examples include a shape having a convex portion in the central region as shown in FIG. 5 above, and a shape in which the thickness gradually decreases from the thickest part c1 toward the end e1 as shown in FIG. 6.

[0129] When the central region has a convex portion, the shape of the convex portion may be a shape constituted by a curved surface as shown in FIG. 5, or may be a shape constituted by a flat surface.

[0130] The lower limit of the thickness of the thickest part c1 is preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more, while the upper limit is preferably 10,000 μm or less, more preferably 5,000 μm or less, and even more preferably 3,000 μm or less.

[0131] The lower limit of the thickness of the end portion e1 is preferably 0 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, while the upper limit is preferably 3000 μm or less, more preferably 1000 μm or less, and even more preferably 500 μm or less.

[0132] In this embodiment, the lower limit of the difference between the thickness of the thickest part c1 and the thickness of the end part e1 is preferably 1 μm or more, more preferably 10 μm or more, and even more preferably 30 μm or more, while the upper limit is preferably 10,000 μm or less, more preferably 5,000 μm or less, and even more preferably 3,000 μm or less.

[0133] The shape of the protective layer in this embodiment may further have the features described above in "A-1. First embodiment", "1. Protective layer", "(1) Shape of protective layer".

[0134] (2) Physical properties of the protective layer The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0135] (3) Protective layer material The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0136] (4) Layer structure of protective layer The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0137] (5) Method for forming protective layer The method for forming the protective layer in this embodiment is not particularly limited as long as it is a method capable of forming a protective layer in which the thickness of the above-mentioned end portion is thinner than the thickest portion in the central region of the protective layer. Specifically, for example, in the case of extrusion molding, it is possible to form a protective layer having the above-mentioned shape by adjusting the shape of the die. Alternatively, after forming a sheet-like protective layer, the protective layer may be mechanically processed to form the above-mentioned shape.

[0138] The surface of the protective layer on the adhesive layer side may be subjected to an easy-adhesion treatment if necessary. This can improve the adhesion to the adhesive layer. In addition, when the protective layer is multi-layered, the surface of the polyolefin resin film opposite to the adhesive layer may be subjected to an easy-adhesion treatment if necessary. This can improve the adhesion between the polyolefin resin film and the surface film or primer film. Examples of the easy-adhesion treatment include corona discharge treatment, plasma treatment, and ozone treatment.

[0139] 2.Adhesive layer The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0140] 3. Other configurations The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0141] 4.Properties of protective film The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0142] 5.Applications The protective film of this embodiment is attached to the surface of the blade of a wind power generator. For example, as shown in Figures 4(a) and 4(b), the protective film 10 is preferably disposed on the tip 22 of the leading edge 21 of the blade 20, but may be disposed on the entire leading edge 21, or may be disposed on the blade portion 23 other than the leading edge 21.

[0143] In the protective film of this embodiment, it is preferable that the central region is disposed on the leading edge 21. This makes it possible to improve the durability of the leading edge 21 portion, reduce air resistance, and improve rotation efficiency.

[0144] A-3. Third embodiment A third embodiment of the protective film for wind power generation device blades of this embodiment has a protective layer and an adhesive layer arranged on one side of the protective layer, and a plurality of convex portions, concave portions, convex ridges, or concave grooves are arranged on the surface of the protective layer opposite the adhesive layer side of the protective layer.

[0145] When generating power, air moves relatively along the blade surface from the leading edge of the blade in a wind turbine blade. At this time, the air flow may separate from the leading edge to the blade surface, creating turbulence. Depending on the rotation speed of the blade, this turbulence may create large vortices (Kármán vortices) with regularity, which may not only generate wind noise but also increase air resistance.

[0146] In order to solve such problems, in this embodiment, a plurality of protrusions, recesses, ridges, or grooves are arranged on the surface of the protective layer opposite the adhesive layer, thereby irregularly generating new small turbulences upwind of the area where Karman vortices are generated, thereby suppressing the generation of larger turbulences such as Karman vortices, thereby suppressing wind noise and preventing an increase in air resistance.

[0147] 1.Protective layer (1) Shape of the protective layer The protective layer in this embodiment has a plurality of projections, recesses, ridges, or grooves arranged on the surface of the protective layer opposite to the adhesive layer.

[0148] Here, "multiple" is not particularly limited as long as it is a number that can irregularly generate new small turbulences as described above, and can be the number that can be formed on the protective layer surface with a specified size and at a specified pitch, as described below.

[0149] The cross-sectional shape of the convex or concave portion, or the convex or concave groove is not particularly limited, and may be, for example, a rectangular shape, a trapezoidal shape, a triangular shape, a semicircular shape, a semi-elliptical shape, etc. For example, Fig. 7(a) is an example in which the cross-sectional shapes of the convex portion 11 and the concave portion 12 are rectangular, Fig. 7(b) is an example in which the cross-sectional shapes of the convex portion 11 and the concave portion 12 are trapezoidal, Fig. 7(c) to (e) are an example in which the cross-sectional shape of the convex portion 11 is triangular, Fig. 7(f) is an example in which the cross-sectional shape of the convex portion 11 is semi-elliptical, Fig. 7(g) to (h) are an example in which the cross-sectional shape of the concave portion 12 is triangular, and Fig. 7(i) is an example in which the cross-sectional shape of the concave portion 12 is semicircular.

[0150] Among these, a trapezoidal shape, a semicircular shape, and a semi-elliptical shape are preferable, since these shapes facilitate the formation of the uneven portion and can enhance the durability of the uneven portion.

[0151] The shape of the recesses or protrusions in a plan view is not particularly limited either, and may be circular, elliptical, rectangular, polygonal, or the like, with a circular shape being preferred.

[0152] In Fig. 7, the size of the convex portion, concave portion, ridge, or groove indicated by W3 is not particularly limited as long as it is a size that can irregularly generate new small turbulences, but the maximum diameter of the convex portion and concave portion, and the upper limit of the size of the cross section of the convex portion and groove are preferably 5.0 cm or less, more preferably 2.5 cm or less, and particularly preferably 0.5 cm or less. The lower limit of the size is usually 0.2 cm or more.

[0153] In addition, the upper limit of the pitch of the convex portion, concave portion, ridge or groove indicated by P1 in Fig. 7 is preferably 10.0 cm or less, more preferably 5.0 cm or less, and particularly preferably 1.0 cm or less. The lower limit of the size is usually 0.001 cm or more.

[0154] Furthermore, the upper limit of the height of the convex portion, concave portion, ridge or groove indicated by H1 in Fig. 7 is preferably 1000 µm or less, more preferably 900 µm or less, and particularly preferably 800 µm or less. The lower limit of the height is preferably 1 µm or more, particularly preferably 10 µm or more, and of these, preferably 30 µm or more.

[0155] When a recess is formed, the recess may penetrate through the protective layer, and if necessary, through the protective layer and the adhesive layer.

[0156] In this embodiment, the upper limit of the thickness of the protective layer in the region where the above-mentioned convex portion, concave portion, ridge, or groove is not formed is preferably 1000 μm or less, more preferably 900 μm or less, and particularly preferably 800 μm or less.The lower limit of the thickness is preferably 1 μm or more, particularly preferably 10 μm or more, and of these, preferably 30 μm or more.

[0157] The shape of the protective layer in this embodiment may further have the features described above in "A-1. First embodiment", "1. Protective layer", "(1) Shape of protective layer".

[0158] In addition, it may further have the features explained above in "A-2. Second embodiment", "1. Protective layer", "(1) Shape of protective layer".

[0159] Furthermore, it may have the features described above in "A-1. First embodiment," "1. Protective layer," and "(1) Shape of protective layer," as well as the features described above in "A-2. Second embodiment," "1. Protective layer," and "(1) Shape of protective layer."

[0160] (2) Physical properties of the protective layer The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0161] (3) Protective layer material The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0162] (4) Layer structure of protective layer The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0163] (5) Method for forming protective layer In the method of forming the protective layer in this embodiment, the protective layer can be formed by extrusion molding or the like, and then the above-mentioned convex portions, concave portions, convex stripes, or concave grooves can be formed by etching, mechanical processing, etc. In addition, during extrusion molding, the protective layer having the present embodiment can be formed by pressing the material against a roll having the above-mentioned convex portions, concave portions, convex stripes, or concave groove shapes immediately after being extruded from a die.

[0164] The surface of the protective layer on the adhesive layer side may be subjected to an easy-adhesion treatment if necessary. This can improve the adhesion to the adhesive layer. In addition, when the protective layer is multi-layered, the surface of the polyolefin resin film opposite to the adhesive layer may be subjected to an easy-adhesion treatment if necessary. This can improve the adhesion between the polyolefin resin film and the surface film or primer film. Examples of the easy-adhesion treatment include corona discharge treatment, plasma treatment, and ozone treatment.

[0165] 2.Adhesive layer The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0166] 3. Other configurations The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0167] 4.Properties of protective film The explanation is the same as that in "A-1. First embodiment" above, so it will not be repeated here.

[0168] 5.Applications The protective film of this embodiment is attached to the surface of the blade of a wind power generator. For example, as shown in Figures 4(a) and 4(b), the protective film 10 is preferably disposed on the tip 22 of the leading edge 21 of the blade 20, but may be disposed on the entire leading edge 21, or may be disposed on the blade portion 23 other than the leading edge 21.

[0169] The protective film of this embodiment may be disposed only on the wing portion 23 other than the leading edge 21. This makes it possible to reduce air resistance and improve rotation efficiency.

[0170] In this embodiment, in the case of a protective film having a convex shape or a concave groove formed in the protective layer, it is preferable that the convex shape or the concave groove is arranged so as not to intersect perpendicularly with the leading edge when installed on the blade, and in particular, it is preferable that the convex shape or the concave groove is arranged so that the intersection angle between the extension line of the convex shape or the concave groove and the leading edge is 45° or less, in order to further reduce air resistance and improve rotation efficiency.

[0171] B. Wind turbine blades The blades of the wind turbine generator in the present disclosure have the protective film of the first, second or third embodiment described above on their surfaces.

[0172] Fig. 4(a) is a schematic perspective view showing an example of a blade in the present disclosure, and Fig. 4(b) is a cross-sectional view taken along line AA in Fig. 4(a). As shown in Fig. 4(a) and Fig. 4(b), a blade 20 has a protective film 10 on its surface. In Fig. 4(a) and Fig. 4(b), the protective film 10 is disposed on a tip 22 of a leading edge 21 of the blade 20.

[0173] In the present disclosure, by having the above-mentioned protective film, it is possible to suppress damage to the blade, reduce air resistance, and improve rotation efficiency.

[0174] The protective films of the first and second embodiments are preferably disposed on the leading edge of the blade, and more preferably disposed on the tip of the leading edge of the blade, because damage to the blade mainly occurs at the tip of the leading edge.

[0175] The structure and materials of the blade are the same as those of a general blade, so a description thereof will be omitted here.

[0176] C. Wind power generation equipment The wind turbine generator of the present disclosure includes the blade described above.

[0177] Fig. 8 is a schematic diagram showing an example of a wind power generation device in the present disclosure. As shown in Fig. 8, the wind power generation device 30 includes a rotor 32 having a blade 20 and a hub 31 supporting the blade 20, a nacelle 33, and a tower 34 supporting the rotor 32 and the nacelle 33. Although not shown, the nacelle 33 houses a main shaft connected to the hub 31 and rotating together with the hub 31, a speed increaser connected to the main shaft for increasing the rotation speed, and a generator that rotates the rotor at the rotation speed increased by the speed increaser to generate electricity. In Fig. 8, the protective film 10 of the first embodiment, the second embodiment, or the third embodiment described above is disposed on the tip of the leading edge of the blade 20.

[0178] In the present disclosure, by having the above-mentioned blade, it is possible to suppress damage to the blade, reduce air resistance, and improve rotation efficiency.

[0179] The components constituting the wind turbine generator are similar to those of a typical wind turbine generator, and therefore a description thereof will be omitted here.

[0180] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present disclosure.

[0181] The present disclosure provides the following inventions. [1] A protective layer and an adhesive layer disposed on one surface of the protective layer, A protective film for blades of a wind turbine generator, wherein the protective layer has end regions each configured to have a thickness that decreases toward the end. [2] A protective layer and an adhesive layer disposed on one surface of the protective layer, The protective film for a blade, wherein the protective layer is configured so that the thickness of the end portion is thinner than the thickest portion in the central region of the protective layer. [3] A protective layer and an adhesive layer disposed on one surface of the protective layer, A protective film for a blade, comprising a plurality of projections, recesses, ridges, or grooves disposed on a surface of the protective layer opposite to the adhesive layer. [4] The protective film for a blade according to [1], wherein the protective layer is configured so that the thickness of the end portion is thinner than the thickest portion in the central region of the protective layer. [5] The protective film for a blade described in [1], wherein a plurality of convex portions, concave portions, convex stripes, or concave grooves are arranged on the surface of the protective layer opposite the adhesive layer side of the protective layer. [6] The protective film for a blade described in [2], wherein a plurality of convex portions, concave portions, convex stripes, or concave grooves are arranged on the surface of the protective layer opposite the adhesive layer side of the protective layer. [7] The protective film for a blade described in [4], wherein a plurality of convex portions, concave portions, convex stripes, or concave grooves are arranged on the surface of the protective layer opposite the adhesive layer side of the protective layer. [8] The protective film for blades according to any one of [1] to [7], wherein the protective layer contains a polyolefin resin. [9] A blade for a wind power generation device having, on its surface, a blade protective film according to any one of [1] to [8].

[10] A wind turbine generator comprising the blade described in [9]. [Explanation of symbols]

[0182] 1 … protective layer 2 … Adhesive layer 10 … Protective film 20 … Blade 30 … Wind power generation equipment

Claims

1. A protective layer and an adhesive layer disposed on one surface of the protective layer, A protective film for blades of a wind turbine generator, wherein the protective layer has end regions each configured to have a thickness that decreases toward the end.

2. A protective layer and an adhesive layer disposed on one surface of the protective layer, The protective film for a blade, wherein the protective layer is configured so that the thickness of the end portion is thinner than the thickness of a central region of the protective layer that is the thickest portion.

3. A protective layer and an adhesive layer disposed on one surface of the protective layer, A protective film for a blade, comprising a surface of the protective layer opposite to the adhesive layer, the surface having a plurality of projections, recesses, ridges, or grooves.

4. The blade protective film according to claim 1 , wherein the protective layer is configured so that the thickness of the end portion is thinner than the thickness of a central region of the protective layer that is the thickest portion.

5. The protective film for a blade according to claim 1 , wherein a plurality of projections, recesses, ridges, or grooves are arranged on a surface of the protective layer opposite to the adhesive layer.

6. The protective film for a blade according to claim 2 , wherein a plurality of projections, recesses, ridges, or grooves are arranged on a surface of the protective layer opposite to the adhesive layer.

7. The protective film for a blade according to claim 4 , wherein a plurality of projections, recesses, ridges, or grooves are arranged on a surface of the protective layer opposite to the adhesive layer side.

8. The protective film for blades according to any one of claims 1 to 7, wherein the protective layer comprises a polyolefin resin.

9. A blade for a wind turbine generator, having a surface thereof coated with the blade protection film according to any one of claims 1 to 7.

10. A wind turbine generator comprising a blade according to claim 9.

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