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

Abstract

The present disclosure provides a protective film for a blade of a wind power generator, the protective film having a protective layer containing a polyolefin resin, and an adhesive layer disposed on one surface of the protective layer, wherein the protective layer has a tensile elastic modulus of 5-35 MPa.

Description

Protective film for blades of wind turbine generator, blade of wind turbine generator, and wind turbine generator

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

[0002] The blades of wind turbines are exposed to ultraviolet rays from sunlight, wind, rain, snow, hail, sleet, lightning, seawater, gas, sand, dust, and other elements. They can also be affected by collisions with birds, insects, and flying objects. Because the blades are exposed to such harsh environments, they can suffer from problems such as damage, deformation, surface contamination, and surface peeling over time. Furthermore, because the blades rotate at high speeds, the likelihood of damage, deformation, surface contamination, and surface peeling increases. These problems can lead to a decrease in power generation efficiency. In the worst case scenario, the blades can break or even fall off.

[0003] Therefore, in order to protect the blade, a technique of placing a protective film or a protective cover on the surface of the blade has been proposed (Patent Documents 1 and 2).

[0004] International Publication No. 2012 / 102294 Special Publication No. 2018-503775

[0005] Patent Document 2 discloses a protective cover made of a polyurethane material. However, polyurethane-based resins are prone to deterioration over time. Therefore, protective films and protective covers made of polyurethane-based resins have the problem of performance degradation due to deterioration over time.

[0006] The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide a protective film for wind turbine blades that has good durability.

[0007] One embodiment of the present disclosure provides a protective film for wind turbine blades, the protective film having a protective layer containing a polyolefin resin and an adhesive layer disposed on one surface of the protective layer, wherein the tensile modulus of the protective layer is 5 MPa or more and 35 MPa or less.

[0008] Another embodiment of the present disclosure provides a blade for a wind turbine generator, the blade having the above-described blade protective film on its surface.

[0009] Another embodiment of the present disclosure provides a wind turbine generator including the blade described above.

[0010] The present disclosure has an effect of providing a protective film for a blade having good durability.

[0011] Fig. 1 is a schematic cross-sectional view illustrating a protective film for blades of a wind turbine generator according to the present disclosure; Fig. 2 is a schematic cross-sectional view illustrating a protective film for blades of a wind turbine generator according to the present disclosure; Fig. 3 is a schematic perspective view and a cross-sectional view illustrating blades of a wind turbine generator according to the present disclosure; Fig. 4 is a schematic view illustrating a wind turbine generator according to the present disclosure;

[0012] Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different forms and should not be construed as being limited to the description of the embodiments exemplified below. Furthermore, to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual form, but these are merely examples and should not be construed as limiting the interpretation of the present disclosure. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0013] In this specification, when describing a mode in which another component is placed on a certain component, the term "above" or "below" is used, unless otherwise specified, to include both a case in which another component is placed directly above or below a certain component so as to be in contact with the component, and a case in which another component is placed above or below a certain component with another component interposed therebetween. Also, in this specification, when describing a mode in which another component is placed on the surface of a certain component, the term "on the surface side" or "on the surface" is used, unless otherwise specified, to include both a case in which another component is placed directly above or below a certain component so as to be in contact with the component, and a case in which another component is placed above or below a certain component with another component interposed therebetween.

[0014] In this specification, the term "film" also includes a member called a "sheet."

[0015] 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.

[0016] A. Protective Film for Wind Turbine Blades A protective film for wind turbine blades according to the present disclosure has a protective layer containing a polyolefin resin and an adhesive layer disposed on one side of the protective layer, and the tensile modulus of the protective layer is 5 MPa or more and 35 MPa or less.

[0017] In this specification, the "protective film for wind turbine blades" may be abbreviated to simply "protective film".

[0018] Fig. 1 is a schematic cross-sectional view illustrating a protective film according to the present disclosure. The protective film 10 in Fig. 1 has a protective layer 1 containing a polyolefin resin and an adhesive layer 2 disposed on one surface of the protective layer 1. The tensile modulus of the protective layer 1 is within a predetermined range.

[0019] Here, it is known that polyurethane-based resins are used as conventional protective films. However, polyurethane-based resins tend to gradually decompose with long-term use, and the performance of the protective film may deteriorate due to aging. In the present disclosure, a polyolefin-based resin is used for the protective layer of the protective film, thereby preventing such problems. Furthermore, as a result of studies by the inventors of the present disclosure, they have found that a protective film having a protective layer containing a polyolefin-based resin has better durability than a protective film having a protective layer containing a polyurethane-based resin, as described in the Examples section below.

[0020] Furthermore, the inventors of the present disclosure have investigated the durability of a protective film having a protective layer containing a polyolefin-based resin and have found that when a relatively soft polyolefin-based resin is used, the erosion resistance is higher than when a relatively hard polyolefin-based resin is used. This is thought to be because the relatively soft protective layer absorbs impacts and therefore suppresses the occurrence of erosion. In other words, in the present disclosure, durability can be improved by ensuring that the tensile modulus of the protective layer is within a predetermined range.

[0021] Furthermore, in the present disclosure, the tensile modulus of the protective layer is within a predetermined range, so that the ability to conform to the curved surface of the blade can also be improved.

[0022] In addition, polyolefin resins generally tend to have lower densities than polyurethane resins. Therefore, by using a polyolefin resin for the protective layer of the protective film, the protective layer can be made lighter, and the protective film can be made lighter. This prevents the protective film from increasing the blade weight and reduces the decrease in power generation efficiency.

[0023] Furthermore, polyurethane resins generally have hydrophilic properties, while polyolefin resins tend to have hydrophobic properties. Therefore, by using a polyolefin resin for the protective layer of the protective film, moisture adhesion can be suppressed. This can suppress condensation, rain, snow, and ice buildup on the blades due to temperature changes. This can prevent a decrease in power generation efficiency. It can also prevent moisture from penetrating into the blades. This can prevent corrosion and damage to the blades and a decrease in insulation in the electrical system.

[0024] Therefore, the protective film of the present disclosure is suitable as a protective film to be used on the blades of wind turbine generators.

[0025] It is also important to inspect the blades of wind turbine generators periodically and, if necessary, perform maintenance such as repairs. In the present disclosure, the tensile modulus of the protective layer is within a predetermined range and is soft, which not only improves the workability when attaching the protective film to the surface of the blade, but also improves the workability when peeling the protective film from the surface of the blade when replacing the protective film. Furthermore, in the present disclosure, the protective film has good durability, which reduces peeling problems caused by deterioration of the protective film.

[0026] Hereinafter, each configuration of the protective film in the present disclosure will be described.

[0027] 1. Protective Layer The protective layer in the present disclosure is a member containing a polyolefin resin.

[0028] (1) Physical Properties of the Protective Layer (a) Tensile Modulus In the present disclosure, the tensile modulus of the protective layer is 35 MPa or less, or may be 30 MPa or less, 20 MPa or less, or 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 less prone to deformation. Therefore, when wind, rain, snow, hail, sleet, seawater, sand, dust, dirt, birds, insects, flying objects, etc. collide with the surface of a blade having the protective film, the protective layer of the protective film can absorb the impact. Therefore, the occurrence of erosion can be suppressed. Furthermore, the ability to conform 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, or 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 result in reduced erosion resistance or difficulty in handling the protective film. Specifically, the tensile modulus of the protective layer is 5 MPa or more and 35 MPa or less, or may be 5 MPa or more and 30 MPa or less, or 7 MPa or more and 20 MPa or less, or may be 10 MPa or more and 15 MPa or less.

[0029] The tensile modulus is measured using a tensile tester in accordance with ISO 527-3:2018. The tensile modulus is defined as the slope of the stress-strain curve, calculated by the least squares method, between two points at 5% strain and 10% strain. The specific measurement conditions are shown below.

[0030] <Measurement conditions> Test piece: rectangular Test piece size: width 10 mm, length 80 mm Gauge distance: 25 mm Tensile speed: 100 mm / min Test conditions: temperature 25°C, humidity 50% RH Number of test pieces: Measurement was performed on three test pieces, and the arithmetic average value was used.

[0031] 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. A method for removing the adhesive layer includes dissolving the adhesive layer in a solvent. The solvent may be the same as that contained in the adhesive composition used to form the adhesive layer.

[0032] (b) Tensile Breaking Stress In the present disclosure, the tensile breaking stress of the protective layer is, for example, 5 MPa or more, or may be 7 MPa or more, or 10 MPa or more. Having the tensile breaking stress of the protective layer in the above range can improve durability. On the other hand, the tensile breaking stress of the protective layer is, for example, 35 MPa or less, or may be 30 MPa or less, or may be 20 MPa or less. If the tensile breaking stress of the protective layer is too high, the protective film may be difficult to stretch, and its ability to conform to the curved surface of the blade may be reduced. Specifically, the tensile breaking stress of the protective layer is 5 MPa or more and 35 MPa or less, or may be 7 MPa or more and 30 MPa or less, or may be 10 MPa or more and 20 MPa or less.

[0033] 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.

[0034] (c) Tensile Breaking Elongation In the present disclosure, the tensile breaking elongation 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 breaking elongation of the protective layer is in the above range, durability can be improved. On the other hand, the upper limit of the tensile breaking elongation 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 breaking elongation 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.

[0035] 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.

[0036] (d) Type A Durometer Hardness In the present disclosure, the Type A Durometer hardness of the protective layer is preferably, for example, 85 or less, and may be 80 or less, or 75 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 collision with the blade, thereby suppressing the occurrence of erosion. Furthermore, 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, or 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, which may result in reduced erosion resistance or difficulty in handling the protective film. Specifically, the Type A Durometer hardness of the protective layer is 60 or more and 85 or less, or may be 65 or more and 80 or less, or may be 70 or more and 75 or less.

[0037] The Type A durometer hardness is measured using a hardness tester in accordance with JIS K6253-3:2012. However, when measuring by stacking test pieces, 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. Specific measurement conditions are shown below.

[0038] <Measurement conditions> Test piece thickness: 6 mm Test conditions: 23°C, 50% RH Measurement time: 3 seconds

[0039] (e) Unit Weight In the present disclosure, the unit weight of the protective layer is, for example, 900 g / m ２ Preferably, 650 g / m or less ２ or less, and ２ If the unit weight of the protective layer is within the above range, the protective layer tends to be light and thin. Therefore, the weight of the protective film can be reduced. Therefore, the weight of the blade having the protective film can be prevented from increasing, and a decrease in power generation efficiency can be suppressed. On the other hand, the lower limit of the unit weight of the protective layer is not particularly limited, and can be, for example, 40 g / m ２ or more, and 65 g / m ２ or more, and ２ Specifically, the unit weight of the protective layer may be 40 g / m or more. ２ 900g / m or more ２ Preferably, 65 g / m or less ２ 650g / m or more ２ or less, and ２ 450g / m or more ２ It may be the following:

[0040] The unit weight is the weight per unit area. The unit weight is determined by the following method. First, the protective layer is cut into a 10 cm square and the weight is measured. Next, the measured weight is multiplied by 100 and the unit is expressed as g / cm. ２ From g / m ２ When measuring the unit weight of the protective layer, the adhesive layer is removed from the protective film, and the protective layer is taken out. The method for removing the adhesive layer is as described above.

[0041] (f) Water Vapor Permeability In the present disclosure, the water vapor permeability of the protective layer is, for example, 15.0 g / (m ２ 24h) or less, and 10.0g / (m ２ 24h) or less is more preferable, and 5.0g / (m ２ 24h) or less is more preferable, and 3g / (m ２24h) or less, and ２ The water vapor permeability of the protective layer within the above range can prevent moisture from penetrating into the blade. This can prevent corrosion and damage to the blade and deterioration of the insulation of the electrical system. On the other hand, there is no particular limit to the lower limit of 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. As a water vapor permeability measuring device, for example, a "PERMATRAN-w 3 / 33" manufactured by MOCON Corporation 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. In this case, if the protective layer is multilayered, the test piece is mounted in the water vapor permeability measuring device so that the side of the protective layer opposite the adhesive layer is the high humidity side (water vapor supply side). Next, measurement is performed under conditions of a temperature of 40°C and 90% RH. Measurement is performed using 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 for removing the adhesive layer is as described above.

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

[0044] (g) Total Light Transmittance In the present disclosure, 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 wind power generation equipment periodically and, if necessary, perform maintenance such as repairs. If the total light transmittance is within the above range, transparency is good. Therefore, the surface of the blade can be visually confirmed through the protective film, making it easy to determine when to replace the protective film.

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

[0046] (h) Water Contact Angle In the present disclosure, the protective layer is preferably hydrophobic. This can suppress adhesion of water to the blade. This can suppress condensation, rain, snow, and ice accumulation on the blade due to temperature changes. This can suppress a decrease in power generation efficiency. It can also suppress the intrusion of water into the interior of the blade. This can suppress corrosion and damage to the blade and a decrease in insulation of the electrical system.

[0047] Specifically, the water contact angle on the surface of the protective layer is preferably 90° or more, and may be 95° or more, or 100° or more. When the contact angle is in the above range, adhesion of water to the blade can be suppressed. On the other hand, the upper limit of the water contact angle on the surface of the protective layer is not particularly limited, but is, for example, 120° or less. If the contact angle is too high, there is a possibility that adhesion with the adhesive layer and the surface layer described below will decrease. The water contact angle on the surface of the protective layer is, for example, 90° or more and 120° or less, or may be 95° or more and 120° or less, or 100° or more and 120° or less.

[0048] The water contact angle is measured using a contact angle meter by the sessile drop method in accordance with JIS R3257:1999. Specifically, a 2 μL droplet of pure water is dropped onto the surface of the protective layer of the protective film, and the water contact angle is measured 1 second after the droplet lands. The atmosphere is set to a temperature of 25° C. and a humidity of 50% RH. The water contact angle is calculated using the θ / 2 method.

[0049] Generally, polyolefin resins are hydrophobic and tend to have a high contact angle with water.

[0050] (i) 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.

[0051] 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%.

[0052] On the other hand, when the protective layer contains a crosslinked polyolefin resin, the gel fraction of the protective layer is, for example, preferably 50% or more, more preferably 60% 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 50% or more and 90% or less, more preferably 60% or more and 80% or less.

[0053] 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 xylene at 110°C for 24 hours. Next, the resin mesh is removed, dried, and weighed. Next, the masses before and after extraction are compared to measure the mass % of the residual insoluble matter. The mass % of the residual insoluble matter is then taken as the gel fraction.

[0054] A 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, a gel fraction of 0% means that there is absolutely no residual insoluble matter and that the mass % of the residual insoluble matter measured using a precision balance is less than 0.05 mass %.

[0055] The residual insoluble matter does not include pigment components other than the resin components, etc. When the test reveals that impurities other than the resin components are present in the residual insoluble matter, 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 content of these impurities in the resin components in advance.

[0056] (2) Materials for the Protective Layer (a) Polyolefin Resin The polyolefin resin may be obtained by polymerizing only an olefin, or may be obtained by copolymerizing an olefin with a monomer other than an olefin. That is, the polyolefin resin may be composed of only an olefin, or may be composed of an olefin and a monomer other than an olefin. Among these, it is preferable that the polyolefin resin be composed of only an olefin.

[0057] Examples of polyolefin resins include polyethylene resins and polypropylene resins, with polyethylene resins being preferred.

[0058] 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.

[0059] In the copolymer of ethylene and an 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 these, 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. By using an α-olefin having 3 to 8 carbon atoms, good flexibility and good strength can be imparted.

[0060] Specific examples of the copolymer of ethylene and an α-olefin include an ethylene-propylene copolymer, an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, an ethylene-1-octene copolymer, and an ethylene-4-methyl-pentene-1 copolymer.

[0061] A specific example of a copolymer of ethylene and a monomer other than an olefin is an ethylene-vinyl acetate copolymer.

[0062] 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). One type of polyethylene resin may be used alone, or two or more types may be used in combination.

[0063] Among these, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-based linear low-density polyethylene (M-LLDPE), and very low-density polyethylene (VLDPE) are preferred. They have good flexibility, transparency, and processability. Since they can impart good flexibility to the protective layer, the protective layer of the protective film can absorb the impact caused by collision with the blade, thereby suppressing the occurrence of erosion. Furthermore, they can improve the ability to conform to the curved surface of the blade.

[0064] Metallocene linear low-density polyethylene (M-LLDPE) is synthesized using a single-site metallocene catalyst. This type of polyethylene resin has little branching in the side chains and a uniform distribution of comonomers. This allows for a narrow molecular weight distribution and low density, imparting flexibility and strength. Furthermore, the crystallinity distribution is narrow and the crystal size is uniform, so not only are there no large crystals, but the low density also results in low crystallinity. This results in excellent transparency.

[0065] The density of the polyethylene resin is not particularly limited. The density of the polyethylene resin is, for example, 0.950 g / cm ３ or less, and 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-based resin is in the above range, flexibility, transparency, and processability can be improved. Since good flexibility can be imparted to the protective layer, 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. Furthermore, when the density of the polyethylene-based 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-based resin is, for example, 0.850 g / cm ３ or more, and 0.870 g / cm ３ That is, the density of the polyethylene resin may be, for example, 0.850 g / cm ３0.950g / cm or more ３ or less, and 0.850 g / cm ３ 0.930g / cm or more ３ or less, 0.870 g / cm ３ 0.925g / cm or more ３ or less, 0.870 g / cm ３ 0.920g / cm or more ３ It may be the following:

[0066] The density of the polyethylene resin is measured by the pycnometer method in accordance with ISO 1183:2019.

[0067] The melting point of the polyethylene-based resin is not particularly limited. The melting point of the polyethylene-based resin is, for example, 100°C or lower. Polyolefin-based resins tend to become softer when their melting point is low. Therefore, if the melting point is within the above range, the protective layer can be imparted with good flexibility, and the protective layer of the protective film can absorb the impact caused by collision with the blade and suppress the occurrence of erosion. In addition, the ability to conform to the curved surface of the blade can be improved. On the other hand, the melting point of the polyethylene-based resin is, for example, 50°C or higher, and may be 60°C or higher. If the melting point is too low, heat resistance may be reduced.

[0068] The melting point of the resin is measured by a differential scanning calorimeter (DSC) in accordance with ISO 3146: 2000. When two or more melting point peaks are present, the higher temperature is taken as the melting point.

[0069] The melt mass flow rate (MFR) of the polyethylene resin at a temperature of 190°C is, for example, preferably 1 g / 10 min or more and 30 g / 10 min or less, more preferably 1 g / 10 min or more and 25 g / 10 min or less, and even more preferably 1 g / 10 min or more and 20 g / 10 min or less. When the MFR of the polyethylene resin is a predetermined value or less, the strength can be improved. Furthermore, when the MFR of the polyethylene resin is within the above range, the film-forming property and flexibility can be improved.

[0070] The melt mass flow rate (MFR) of a polyethylene resin is measured in accordance with ISO 1133-1: 2011. The measurement conditions are Method A, a temperature of 190°C, and a load of 2.16 kg.

[0071] The polyethylene resin preferably does not contain an ester bond, which allows for excellent hydrolysis resistance.

[0072] 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.

[0073] The cross-linked polyolefin resin refers to a cross-linked polyolefin resin, i.e., a polyolefin resin having cross-linked bonds, whereas the non-cross-linked polyolefin resin refers to a polyolefin resin that is not cross-linked.

[0074] Furthermore, the term "crosslinked polyethylene resin" refers to a polyethylene resin that has been crosslinked, i.e., a polyethylene resin having crosslinked bonds, while the term "non-crosslinked polyethylene resin" refers to a polyethylene resin that has not been crosslinked.

[0075] 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 these, a crosslinking method using a crosslinking agent is preferred.

[0076] As the crosslinking agent, a general crosslinking agent can be used, for example, organic peroxides. Examples of organic peroxides include peroxycarbonates, peroxyketals, and dialkyl peroxides. Examples of peroxycarbonates include t-amyl-peroxy-2-ethylhexyl carbonate and t-butylperoxy-2-ethylhexyl carbonate. Examples of peroxyketals include n-butyl 4,4-di(t-butylperoxy)valerate, ethyl 3,3-di(t-butylperoxy)butyrate, and 2,2-di(t-butylperoxy)butane. Examples of dialkyl peroxides include 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. The crosslinking agent may be used alone or in combination of two or more.

[0077] 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 and the like.

[0078] In addition, in the crosslinking method using a crosslinking agent, a crosslinking aid may be used. By using the crosslinking aid, it is possible to promote an appropriate crosslinking reaction. Furthermore, the crosslinking aid reduces the crystallinity of the polyolefin resin, so that transparency can be maintained. As the crosslinking aid, a general crosslinking aid can be used, and for example, a polyfunctional monomer having a polymerizable functional group can be mentioned.

[0079] Among these, from the viewpoint of improving reactivity, the crosslinking aid is preferably a nurate ring-containing compound having two or more polymerizable functional groups in one molecule.

[0080] In the crosslinking aid, the number of polymerizable functional groups is, for example, preferably 2 to 6 inclusive, more preferably 2 to 3 inclusive per 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.

[0081] The polymerizable functional group is not particularly limited as long as it can react with the polyolefin resin as the base resin and 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.

[0082] Examples of crosslinking aids include polyallyl compounds, poly(meth)acryloxy compounds, and epoxy compounds. Examples of polyallyl compounds include triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate. Examples of 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 epoxy compounds include epoxy compounds containing a double bond and an epoxy group, and epoxy compounds containing two or more epoxy groups. Examples of 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 aids may be used alone or in combination of two or more.

[0083] Among these, it is preferable to use triallyl isocyanurate (TAIC) as the crosslinking aid. Triallyl isocyanurate (TAIC) has good compatibility with linear low-density polyethylene, and can reduce crystallinity by crosslinking to maintain transparency. Furthermore, triallyl isocyanurate (TAIC) can impart flexibility at low temperatures to the protective layer.

[0084] 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 and the like.

[0085] 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, thereby improving transparency and flexibility.

[0086] The proportion of each resin component contained in the protective layer is analyzed from the peak ratio detected by differential scanning calorimetry (DSC).

[0087] (b) Additives The protective layer may contain additives as needed. Examples of additives include light stabilizers, ultraviolet absorbers, antioxidants, heat stabilizers, nucleating agents, dispersants, leveling agents, plasticizers, antifoaming agents, 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.

[0088] Examples of light stabilizers include hindered amine light stabilizers (HALS). Hindered amine light stabilizers are broadly divided into three types depending on the bonding partner of the nitrogen atom in the piperidine skeleton: N-H type (hydrogen bonded to the nitrogen atom), N-R 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 has a faster radical capturing speed than the N-H type and N-R type. Furthermore, N-OR type low molecular weight HALS migrate to the surface faster than polymer HALS, and are more sensitive to radicals than N-H type and N-CH ３ It scavenges radicals for a shorter period of time than HALS, thereby suppressing deterioration of the protective layer.

[0089] The weather-resistant agents such as the above-mentioned light stabilizers, ultraviolet absorbers, and antioxidants may be dispersed in a resin to form a weather-resistant masterbatch and added to the resin composition. The weather-resistant masterbatch may be prepared as appropriate, or a commercially available product may be used. The resin used in the weather-resistant masterbatch may be the above-mentioned polyolefin resin or another resin.

[0090] The content of the additive in the protective layer is, for example, 5% by mass or less.

[0091] (3) 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 containing a polyolefin resin film. When the protective layer has multiple 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 side of the polyolefin resin film opposite the adhesive layer and contains a cured product of an electron beam curable resin composition.

[0092] 2, 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, which is disposed on the surface of the polyolefin resin film 1a opposite to the adhesive layer 2. When the protective layer has a surface film, durability can be further improved.

[0093] The electron beam curable resin composition contains at least an electron beam curable resin, which can be appropriately selected from polymerizable monomers, polymerizable oligomers, and polymerizable prepolymers.

[0094] The surface film may contain an ultraviolet absorber. As will be described later, when a primer film is not disposed between the polyolefin resin film and the surface film, the surface film preferably contains an ultraviolet absorber. On the other hand, when a primer film is disposed between the polyolefin resin film and the surface film, it is preferable that at least one of the surface film and the primer film contains an ultraviolet absorber.

[0095] The ultraviolet absorber may be either an inorganic ultraviolet absorber or an organic ultraviolet absorber.

[0096] The inorganic ultraviolet absorber is preferably, for example, titanium oxide, cerium oxide, or zinc oxide having an average particle size of about 5 nm or more and 120 nm or less.

[0097] Examples of organic ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, and acrylonitrile-based ultraviolet absorbers. Examples of benzotriazole-based 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].

[0098] The surface film may contain additives other than the ultraviolet absorber, if necessary.

[0099] 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-butylmalonate 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.

[0100] Examples of other additives include abrasion resistance improvers, polymerization inhibitors, crosslinking agents, infrared absorbers, antistatic agents, adhesion improvers, leveling agents, thixotropy-imparting agents, coupling agents, plasticizers, antifoaming agents, fillers, solvents, and colorants.

[0101] (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.

[0102] (4) Thickness of the Protective Layer The thickness of the protective layer is not particularly limited as long as a protective layer satisfying the above-described physical properties can be obtained. The thickness of the protective layer is, for example, 50 μm or more, or may be 80 μm or more, or 100 μm or more. When the thickness of the protective layer is within the above range, sufficient erosion resistance can be obtained. On the other hand, the thickness of the protective layer is, for example, 1000 μm or less, or may be 700 μm or less, or may be 500 μm or less. When the thickness of the protective layer is within the above range, the protective film can be easily stretched, and the adhesion and conformability to uneven and curved surfaces can be improved. Furthermore, when the thickness of the protective layer is within the above range, sufficient transparency can be ensured. Specifically, the thickness of the protective layer is 50 μm or more and 1000 μm or less, or may be 80 μm or more and 700 μm or less, or 100 μm or more and 500 μm or less.

[0103] When the protective layer is a multi-layered layer, the thickness of the protective layer mentioned above refers to the thickness of the entire protective layer.

[0104] (5) Method for forming protective layer The protective layer can be obtained, for example, by mixing the above-mentioned components to prepare a resin composition, melting the resin composition, and forming the resin composition into a sheet-like film. After the film formation, a crosslinking treatment may be performed.

[0105] As a method for mixing the components, for example, a method of impregnating the components into a polyolefin resin by dry blending can be mentioned. When the protective layer is obtained by extrusion molding, the crosslinking agent and crosslinking aid may be added in a liquid state to the polyolefin resin. Alternatively, the crosslinking aid may be pre-mixed with the polyolefin resin to form a masterbatch. When a masterbatch is used, the dispersibility of the crosslinking aid is improved.

[0106] The melt molding method may be any common molding method, such as injection molding, extrusion molding, blow molding, compression molding, and rotational molding. The molding temperature may be a temperature above the melting point of the resin composition. Depending on the crosslinking agent, the molding temperature may be a temperature at which crosslinking does not start during film formation, i.e., a temperature at which the gel fraction of the resin composition can be maintained at 0%. The molding temperature is, for example, 80°C or higher and 250°C or lower.

[0107] As described above, examples of the crosslinking treatment include a crosslinking treatment using a crosslinking agent and a crosslinking treatment by irradiation with ionizing radiation.

[0108] The surface of the protective layer facing the adhesive layer may be subjected to an easy-adhesion treatment if necessary. This can improve adhesion to the adhesive layer. Furthermore, when the protective layer is multilayered, the surface of the polyolefin resin film opposite the adhesive layer may be subjected to an easy-adhesion treatment if necessary. This can improve adhesion between the polyolefin resin film and the surface film or primer film. Examples of easy-adhesion treatments include corona discharge treatment, plasma treatment, and ozone treatment.

[0109] 2. Adhesive Layer The adhesive layer in the present disclosure is a member for attaching the protective film to the blades of the wind turbine generator.

[0110] The adhesive layer is not particularly limited as long as it can attach the protective film to the blade, and can be appropriately selected depending on the material of the blade, etc. A common adhesive can be used for the adhesive layer. Examples include ultraviolet-curable adhesives, two-component curable adhesives, and pressure-sensitive adhesives. The ultraviolet-curable adhesives and two-component curable adhesives can increase adhesive strength. Furthermore, pressure-sensitive adhesives have good workability.

[0111] Examples of pressure-sensitive adhesives include acrylic adhesives, urethane adhesives, and silicone adhesives. Among these, acrylic adhesives are preferred because of their excellent transparency, weather resistance, heat resistance, etc.

[0112] 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 depending on the application. The thickness of the adhesive layer is, for example, 25 μm or more, or may be 25 μm or more, or 30 μm or more. The thickness of the adhesive layer is, for example, 120 μm or less, or 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, or may be 25 μm or more and 90 μm or less, or may be 30 μm or more and 80 μm or less.

[0113] 3. Other Configurations The protective film of the present disclosure may have other configurations depending on the application.

[0114] The protective film in the present disclosure may have a separator on the surface of the adhesive layer opposite to the protective layer.

[0115] 4. Physical Properties of Protective Film (1) Adhesion Strength In the protective film of the present disclosure, the adhesion strength to a SUS plate is, for example, preferably 3 N / 10 mm or more, or may be 7 N / 10 mm or more, or may be 10 N / 10 mm or more. Having the adhesion strength in the above range can improve durability. On the other hand, the upper limit of the adhesion strength to a SUS plate is not particularly limited, but is, for example, preferably 30 N / 10 mm or less, or may be 25 N / 10 mm or less, or may be 20 N / 10 mm or less. If the adhesion strength is too high, the workability when replacing the protective film may be reduced. Specifically, the adhesion strength to a SUS plate is preferably 3 N / 10 mm or more and 30 N / 10 mm or less, or may be 7 N / 10 mm or more and 25 N / 10 mm or less, or may be 10 N / 10 mm or more and 20 N / 10 mm or less.

[0116] The adhesive strength to SUS plate is measured in accordance with Method 6 of JIS Z0237:2009. Specific measurement conditions are shown below. The tensile tester used is, for example, "Tensilon RTF1150" manufactured by A&D Co., Ltd. The SUS plate used is a steel plate of SUS304 with a surface finish of BA.

[0117] <Measurement conditions> Tape width: 10 mm Peeling speed: 300 mm / min Peeling angle: 90 degrees Test conditions: 23°C, 50% RH Number of tests: Measurement was carried out on 3 test pieces, and the arithmetic average value was used.

[0118] In the protective film of the present disclosure, the adhesive strength to the fluororesin layer is, for example, preferably 2.5 N / 10 mm or more, or may be 4 N / 10 mm or more, or may be 5 N / 10 mm or more. Having the adhesive strength in the above range can improve durability. Meanwhile, 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, or may be 25 N / 10 mm or less, or may be 20 N / 10 mm or less. If the adhesive strength is too high, the workability when replacing the protective film may be impaired. Specifically, the adhesive strength to the fluororesin layer is preferably 2.5 N / 10 mm or more and 30 N / 10 mm or less, or 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.

[0119] The adhesive strength to the fluororesin layer is measured in accordance with Method 6 of JIS Z0237:2009. Specific measurement conditions are the same as those for measuring the adhesive strength to the SUS plate. As a tensile tester, for example, "Tensilon RTF1150" manufactured by A&D Co., Ltd. is used. As a test plate, a test plate prepared by the following method is used instead of the SUS plate. A fluororesin paint ("Wind Hullo Topcoat F" manufactured by Nippon Tokushu Toryo Co., Ltd.) is applied to one side of the SUS substrate by a roller method to form a fluororesin layer with a thickness of 100 μm to 150 μm, and this is used as a test plate.

[0120] In addition, in the protective film according to the present disclosure, the adhesive strength (N / 10 mm) to the fluororesin layer is preferably equal to or greater than the tensile load (N) of the protective layer at 10% elongation, thereby improving durability.

[0121] The tensile load at 10% elongation of the protective layer is measured using a tensile tester in accordance with ISO 527-3:2018. The measurement conditions are the same as those for measuring the tensile modulus. For example, a "Tensilon RTF1150" manufactured by A&D Co., Ltd. is used as the tensile tester.

[0122] (2) Total Light Transmittance In the present disclosure, 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, transparency is good. Therefore, the surface of the blade can be visually confirmed through the protective film, making it easy to determine when to replace the protective film. The total light transmittance is measured in accordance with ISO 13468-1:1996.

[0123] (3) Erosion Depth In the present disclosure, the erosion depth from the surface of the protective film on the protective layer side when the amount of projected particles is 40 g, as obtained by a micro slurry jet erosion (MSE) test, is, for example, preferably 10 μm or less, or may be 8 μm or less, or may be 5 μm or less. If the erosion depth is within the above range, durability can be improved. There is no particular limitation on the lower limit of the erosion depth.

[0124] The erosion depth is a value obtained by a micro-slurry jet erosion (MSE) test, in which a fixed 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.

[0125] The erosion depth is measured using an MSE tester "MSE-A" manufactured by Palmeso Co., Ltd. The measurement conditions are as follows: The surface of the protective film on the protective layer side is used as the sample surface, and measurements are taken at three locations, and the arithmetic average value is used.

[0126] <Measurement conditions> Particles: Polygonal alumina (average particle diameter 1.2 μm) Projection particle speed: 360 km / hour Test conditions: 25°C, 50% RH

[0127] (4) Thickness Uniformity In the present disclosure, it is preferable that the thickness of the protective film is uniform. If the protective film has an extremely thin portion, the protective film may stretch from that portion, which may result in a difference in durability within the protective film surface. Specifically, when the maximum thickness of the protective film is 100%, the minimum thickness of the protective film is preferably 80% or more, and more preferably 90% or more.

[0128] The thickness of the protective film is measured using a contact thickness gauge in accordance with JIS K7130:1999. The thickness of the protective film is measured at multiple locations in both the vertical and horizontal directions. For example, in the case of a protective film measuring 30 cm in length and 20 cm in width, the thickness of the protective film is measured at 10 locations at 3 cm intervals in the vertical direction and at 10 locations at 2 cm intervals in the horizontal direction. For example, an "ID-C112X" manufactured by Mitutoyo Corporation is used as the contact thickness gauge.

[0129] 5. Uses The protective film of the present disclosure is attached to the surface of the blade of a wind turbine. For example, as shown in Figures 3(a) and 3(b), the protective film 10 is placed on the tip 22 of the leading edge 21 of the blade 20.

[0130] B. Blades of Wind Turbine Power Generation Device The blades of the wind turbine power generation device in the present disclosure have the above-described protective film on their surfaces.

[0131] Fig. 3(a) is a schematic perspective view showing an example of a blade according to the present disclosure, and Fig. 3(b) is a cross-sectional view taken along line A-A in Fig. 3(a). As shown in Fig. 3(a) and Fig. 3(b), a blade 20 has a protective film 10 on its surface. In Fig. 3(a) and Fig. 3(b), the protective film 10 is disposed on a tip 22 of a leading edge 21 of the blade 20.

[0132] In the present disclosure, the occurrence of erosion can be suppressed by having the above-described protective film.

[0133] The protective film is preferably disposed on the leading edge of the blade, and more preferably on the tip of the leading edge of the blade, because erosion mainly occurs at the tip of the leading edge.

[0134] The structure and materials of the blade are the same as those of a general blade, so a description thereof will be omitted here.

[0135] C. Wind Turbine Generator The wind turbine generator of the present disclosure includes the blades described above.

[0136] Fig. 4 is a schematic diagram showing an example of a wind turbine generator according to the present disclosure. As shown in Fig. 4, the wind turbine generator 30 includes a rotor 32 having blades 20 and a hub 31 supporting the blades 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 step-up gear connected to the main shaft for increasing the rotational speed, and a generator that generates electricity by rotating the rotor at the rotational speed increased by the step-up gear. In Fig. 4, a protective film 10 is disposed on the tip of the leading edge of the blade 20.

[0137] In the present disclosure, by having the above-described blade, it is possible to suppress the occurrence of erosion in the blade.

[0138] The components that make up the wind turbine generator are similar to those of a general wind turbine generator, and therefore a description thereof will be omitted here.

[0139] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure.

[0140] The present disclosure will be described in more detail below with reference to examples and comparative examples.

[0141] [Production Example A1] The following base resin and weathering agent masterbatch were used. Base resin: Density 0.901 g / cm ３, a metallocene-based linear low-density polyethylene resin (M-LLDPE) having a melting point of 93 ° C. and an MFR of 2.0 g / 10 min at 190 ° C. Weather resistance masterbatch: a density of 0.880 g / cm ３ 100 parts by mass of a low-density polyethylene resin having an MFR of 3.5 g / 10 min at 190°C was mixed with 0.6 parts by mass of HALS1 ("KEMISTAB62" manufactured by Chemipro Chemical Co., Ltd.), 3.5 parts by mass of ultraviolet absorber 1 ("KEMISORB12" manufactured by Chemipro Chemical Co., Ltd.), and 0.6 parts by mass of ultraviolet absorber 2 ("KEMISORB79" manufactured by Chemipro Chemical Co., Ltd.).

[0142] A resin composition was prepared by mixing 95 parts by mass of the base resin with 5 parts by mass of the weathering agent masterbatch. Using a film molding machine equipped with a φ30 mm extruder and a 200 mm wide T-die, the resin composition was extruded into a sheet at an extrusion temperature of 210°C to form a protective layer with a thickness of 300 μm. The take-up speed was adjusted to obtain a predetermined thickness. Regarding the cooling roll and rubber roll immediately below the T-die, the cooling roll was a chrome-plated cooling roll with a surface roughness Rz of 1.5 μm, and the rubber roll was a silicone rubber roll with a hardness of 70 degrees.

[0143] [Production Example A2] A protective layer was formed in the same manner as in Production Example A1, except that the following base resin and weather resistance agent masterbatch were used: Base resin: Density 0.87 g / cm ３ Low-density polyethylene resin (LDPE) having a melting point of 55°C and an MFR of 3.6 g / 10 min at 190°C Weather resistance masterbatch: density of 0.880 g / cm ３ 100 parts by mass of a low-density polyethylene resin having an MFR of 3.5 g / 10 min at 190°C was mixed with 0.6 parts by mass of HALS ("KEMISTAB62" manufactured by Chemipro Chemical Co., Ltd.), 3.5 parts by mass of ultraviolet absorber 1 ("KEMISORB12" manufactured by Chemipro Chemical Co., Ltd.), and 0.6 parts by mass of ultraviolet absorber 2 ("KEMISORB79" manufactured by Chemipro Chemical Co., Ltd.).

[0144] [Production Example A3] A protective layer was formed in the same manner as in Production Example A1, except that the following base resin and weather resistance agent masterbatch were used: Base resin: Density 0.88 g / cm３ , a metallocene-based linear low-density polyethylene resin (M-LLDPE) having a melting point of 60 ° C. and an MFR of 3.5 g / 10 min at 190 ° C. Weather resistance masterbatch: a density of 0.880 g / cm ３ 100 parts by mass of a low-density polyethylene resin having an MFR of 3.5 g / 10 min at 190°C was mixed with 0.6 parts by mass of HALS ("KEMISTAB62" manufactured by Chemipro Chemical Co., Ltd.), 3.5 parts by mass of ultraviolet absorber 1 ("KEMISORB12" manufactured by Chemipro Chemical Co., Ltd.), and 0.6 parts by mass of ultraviolet absorber 2 ("KEMISORB79" manufactured by Chemipro Chemical Co., Ltd.).

[0145] [Production Example A4] A protective layer was formed in the same manner as in Production Example A1, except that the following base resin and weather resistance agent masterbatch were used: Base resin: Density 0.960 g / cm ３ ethylene-vinyl acetate copolymer resin (EVA) having a melting point of 61°C and an MFR of 30g / 10min at 190°C Weather resistance masterbatch: density of 0.960g / cm ３ 100 parts by mass of an ethylene-vinyl acetate copolymer resin having a melting point of 61°C and an MFR at 190°C of 30 g / 10 min was mixed with 0.6 parts by mass of HALS ("KEMISTAB62" manufactured by Chemipro Chemical Co., Ltd.), 3.5 parts by mass of ultraviolet absorber 1 ("KEMISORB12" manufactured by Chemipro Chemical Co., Ltd.), and 0.6 parts by mass of ultraviolet absorber 2 ("KEMISORB79" manufactured by Chemipro Chemical Co., Ltd.).

[0146] [Production Example A5] The following base resin and weathering agent masterbatch were used: Base resin 1: Density 0.87 g / cm ３ Low-density polyethylene resin (LDPE) having a melting point of 55°C and an MFR of 1.2 g / 10 min at 190°C. Base resin 2: Density of 0.901 g / cm ３ Metallocene-based linear low-density polyethylene resin (M-LLDPE) with a melting point of 93°C and an MFR of 2.0 g / 10 min at 190°C. Weather resistance masterbatch: density of 0.880 g / cm ３100 parts by mass of a low-density polyethylene resin having an MFR of 3.5 g / 10 min at 190°C was mixed with 0.6 parts by mass of HALS ("KEMISTAB62" manufactured by Chemipro Chemical Co., Ltd.), 3.5 parts by mass of ultraviolet absorber 1 ("KEMISORB12" manufactured by Chemipro Chemical Co., Ltd.), and 0.6 parts by mass of ultraviolet absorber 2 ("KEMISORB79" manufactured by Chemipro Chemical Co., Ltd.).

[0147] Resin composition 1 was prepared by mixing 95 parts by mass of the base resin 1 with 5 parts by mass of the weathering agent masterbatch. Resin composition 2 was prepared by mixing 95 parts by mass of the base resin 2 with 5 parts by mass of the weathering agent masterbatch. Using a film molding machine equipped with a φ30 mm extruder and a 200 mm wide T-die, resin compositions 1 and 2 were extruded at a temperature of 210°C to form a three-layer sheet consisting of resin composition 1, resin composition 2, and resin composition 1 in that order. The thicknesses of the individual layers were 30 μm, 260 μm, and 30 μm, forming a protective layer with a total thickness of 300 μm. The take-up speed was adjusted to achieve the desired thickness. Regarding the cooling roll and rubber roll immediately below the T-die, the cooling roll was a chrome-plated cooling roll with a surface roughness Rz of 1.5 μm, and the rubber roll was a silicone rubber roll with a hardness of 70 degrees.

[0148] [Production Example B1] 70 g of water-dispersible polycarbonate-based polyurethane A (cyclohexane skeleton content: approximately 36% by mass), 0.85 g of ultraviolet absorber 3 ("Tinuvin 1130" manufactured by BASF Japan), 0.5 g of HALS2 ("Tinuvin 292" manufactured by BASF Japan), 0.2 g of Triton GR-7M (surfactant manufactured by The Dow Chemical Company), 0.1 g of neutralizer ("AMP95" manufactured by ANGUS Chemical Company), and 3 g of deionized water were mixed and stirred to prepare a pre-solution. The pre-solution was bar-coated onto a PET film, dried at 90 ° C. for 3 minutes in a hot air oven, and further dried and cured at 160 ° C. for 3 minutes. This formed a protective layer having a thickness of 300 μm.

[0149] [Production Example B2] A protective layer was formed in the same manner as in Production Example A1, except that the following base resin and weather resistance agent masterbatch were used: Base resin: Density 1.15 g / cm ３Urethane resin / weather-resistant agent masterbatch having a glass transition point of −25° C.: 100 parts by mass of the above urethane resin was mixed with 0.6 parts by mass of HALS (KEMISTAB62 manufactured by Chemipro Chemicals), 3.5 parts by mass of ultraviolet absorber 1 (KEMISORB12 manufactured by Chemipro Chemicals), and 0.6 parts by mass of ultraviolet absorber 2 (KEMISORB79 manufactured by Chemipro Chemicals).

[0150] [Production Example B3] The following base resin and weathering agent masterbatch were used. Base resin: Density 0.93 g / cm ３ High-density polyethylene resin (HDPE) having a melting point of 130°C or less and an MFR of 1.5g / 10min at 190°C Weather resistance masterbatch: density of 0.880g / cm ３ 100 parts by mass of a low-density polyethylene resin having an MFR of 3.5 g / 10 min at 190°C was mixed with 0.6 parts by mass of HALS ("KEMISTAB62" manufactured by Chemipro Chemical Co., Ltd.), 3.5 parts by mass of ultraviolet absorber 1 ("KEMISORB12" manufactured by Chemipro Chemical Co., Ltd.), and 0.6 parts by mass of ultraviolet absorber 2 ("KEMISORB79" manufactured by Chemipro Chemical Co., Ltd.).

[0151] A resin composition was prepared by mixing 95 parts by mass of the base resin with 5 parts by mass of the weathering agent masterbatch. Using a film molding machine equipped with a φ30 mm extruder and a 200 mm wide T-die, the resin composition was extruded into a sheet at an extrusion temperature of 210°C to form a protective layer with a thickness of 300 μm. The take-up speed was adjusted to obtain a predetermined thickness. Regarding the cooling roll and rubber roll immediately below the T-die, a chrome-plated cooling roll with a surface roughness Rz of 1.5 μm was used, and a silicone rubber roll with a hardness of 70 degrees was used.

[0152] [Production Example B4] A protective layer was formed in the same manner as in Production Example B3, except that the following base resin and weather resistance agent masterbatch were used: Base resin: Density 0.864 g / cm ３ Low-density polyethylene resin (LDPE) having a melting point of 50°C or less and an MFR of 3.6 g / 10 min at 190°C Weather resistance masterbatch: density of 0.880 g / cm ３100 parts by mass of a low-density polyethylene resin having an MFR of 3.5 g / 10 min at 190°C was mixed with 0.6 parts by mass of HALS ("KEMISTAB62" manufactured by Chemipro Chemical Co., Ltd.), 3.5 parts by mass of ultraviolet absorber 1 ("KEMISORB12" manufactured by Chemipro Chemical Co., Ltd.), and 0.6 parts by mass of ultraviolet absorber 2 ("KEMISORB79" manufactured by Chemipro Chemical Co., Ltd.).

[0153] [Evaluation 1] (1) Tensile modulus The tensile modulus of the protective layer was determined by the method described above in "A. Protective film for blades of wind turbine generator 1. Protective layer (1) Physical properties of the protective layer (a) Tensile modulus". The tensile tester used was "Tensilon RTF1150" manufactured by A&D Co., Ltd.

[0154] (2) Tensile Breaking Stress The tensile breaking stress of the protective layer was measured by the method described above in "A. Protective film for blades of wind turbine generator 1. Protective layer (1) Physical properties of the protective layer (b) Tensile breaking stress." The tensile testing machine used was "Tensilon RTF1150" manufactured by A&D Co., Ltd.

[0155] (3) Tensile Breaking Elongation The tensile breaking elongation of the protective layer was determined by the method described above in "A. Protective film for blades of wind turbine generator 1. Protective layer (1) Physical properties of the protective layer (c) Tensile Breaking Elongation." The tensile testing machine used was "Tensilon RTF1150" manufactured by A&D Co., Ltd.

[0156] (4) Type A Durometer Hardness The Type A Durometer hardness of the protective layer was measured by the method described above in "A. Protective film for blades of wind turbine generators 1. Protective layer (1) Physical properties of the protective layer (d) Type A Durometer hardness." The hardness tester used was "GS-610" manufactured by TECLOCK Corporation.

[0157] (5) Unit Weight The unit weight of the protective layer was determined by the method described above in "A. Protective film for blades of wind turbine generator 1. Protective layer (1) Physical properties of protective layer (e) Unit weight".

[0158] (6) Water Vapor Permeability The water vapor permeability of the protective layer was measured by the method described above in "A. Protective film for blades of wind turbine generator 1. Protective layer (1) Physical properties of protective layer (f) Water vapor permeability."

[0159] (7) Water Contact Angle The water contact angle on the surface of the protective layer was determined by the method described above in "A. Protective film for blades of wind turbine generator 1. Protective layer (1) Physical properties of the protective layer (h) Water contact angle." The contact angle meter used was a contact angle measuring instrument "Drop Master-700" manufactured by Kyowa Interface Science Co., Ltd.

[0160] (8) Total Light Transmittance The total light transmittance of the protective layer was determined using a haze meter "HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd., according to the method described above in "A. Protective film for blades of wind power generator 1. Protective layer (1) Physical properties of protective layer (g) Total light transmittance." At this time, the measurement was also performed on protective layers formed by changing the thickness from 300 μm to 600 μm and 900 μm.

[0161] (9) Conformability A pressure-sensitive adhesive composition was prepared by blending the following components. <Adhesive composition> Adhesive: (meth)acrylic acid alkyl ester copolymer (Nippon Carbide Industries Co., Ltd. "Nissetsu KP-2826", solid content: 30 mass%, solvent: methyl ethyl ketone, ethyl acetate) 100 parts by mass Crosslinking agent: chelating compound (Nippon Carbide Industries Co., Ltd. "Nissetsu CK-401", solid content: 5 mass%, solvent: toluene) 0.3 parts by mass Silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM-403", solid content: 100 mass%) 0.15 parts by mass Phenolic antioxidant: ADEKA Corporation "ADK STAB AO-60G", solid content: 100 mass%) 0.38 parts by mass Ultraviolet absorber: ADEKA Corporation "ADK STAB LA-24", solid content: 100 mass%) 0.38 parts by mass

[0162] Next, the pressure-sensitive adhesive composition was applied to a release-treated surface of a 50 μm-thick PET separator ("PET50x1-J2" manufactured by Nippa Corporation) so that the thickness after drying would be 65 μm, and then dried to form an adhesive layer. Thereafter, the laminate of the separator and adhesive layer was laminated onto one side of the protective layer of each production example to obtain a protective film.

[0163] The adherend used was a U-shaped handle made of polyamide, 20 mm in diameter, 56 mm in height, and 148 mm in length. The protective film was cut to a width of 20 mm and a length of 100 mm. The protective film was attached to a rounded portion of the adherend, and the appearance was visually inspected after 24 hours. The conformability was evaluated according to the following criteria: A: No lifting or peeling occurred. B: Lifting or peeling occurred in less than 10% of the attached area. C: Lifting or peeling occurred in 10% or more of the attached area.

[0164] (10) Erosion Depth A protective film was prepared as described in (9) above. The erosion depth from the surface of the protective film facing the protective layer when the amount of projected particles was 40 g was obtained by a microslurry jet erosion (MSE) test using the method described in "A. Protective film for blades of wind power generators, 4. Physical properties of the protective film, (3) Erosion depth" above.

[0165] (11) Durability Test The following durability test was carried out on the protective layer or protective film using an "EYE SUPER UV TESTER / SUV-W261" manufactured by Iwasaki Electric Co., Ltd. <Durability test conditions> UV irradiation conditions Light source: metal halide lamp Illuminance: 96 mW / cm ２ (Wavelength 300nm to 400nm) Black panel temperature: 63°C Humidity: 50% RH Time: 20 hours Condensation conditions (no irradiation) Humidity: 98% RH Time: 4 hours Cycle 1 cycle: UV irradiation 20 hours, condensation 4 hours Number of cycles: 15 cycles Total irradiation time: 300 hours

[0166] The tensile stress at break of the protective layer after the durability test was measured, and the tensile stress at break retention rate was calculated. Similarly, the tensile elongation at break of the protective layer after the durability test was calculated, and the tensile elongation at break retention rate was calculated. In addition, the erosion depth before and after the durability test was calculated, and the erosion depth retention rate before and after the durability test was calculated. The erosion depth retention rate was determined based on the thickness of the protective layer at the time of film formation.

[0167]

[0168]

[0169]

[0170]

[0171] In Production Examples A1 to A5, the protective layer contained an olefin-based resin, and the tensile modulus of the protective layer was within a predetermined range, so durability was good. On the other hand, in Production Examples B1 and B2, the protective layer contained a polyurethane-based resin, so durability was poor. In Production Example B3, although the protective layer contained an olefin-based resin, the tensile modulus of the protective layer was high, so conformability to curved surfaces was poor. In Production Example B4, although the protective layer contained an olefin-based resin, the tensile modulus of the protective layer was low, so erosion resistance was poor.

[0172] Example 1 First, a protective layer was formed in the same manner as in Production Example A1.

[0173] The following components were mixed to prepare a pressure-sensitive adhesive composition. <Adhesive composition> Adhesive: (meth)acrylic acid alkyl ester copolymer (Nippon Carbide Industries Co., Ltd. "Nissetsu KP-2826", solid content: 30 mass%, solvent: methyl ethyl ketone, ethyl acetate) 100 parts by mass Crosslinker: chelating compound (Nippon Carbide Industries Co., Ltd. "Nissetsu CK-401", solid content: 5 mass%, solvent: toluene) 0.3 parts by mass Silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM-403", solid content: 100 mass%) 0.15 parts by mass Phenolic antioxidant (ADEKA Corporation "ADK STAB AO-60G", solid content: 100 mass%) 0.38 parts by mass Ultraviolet absorber (ADEKA Corporation "ADK STAB LA-24", solid content: 100 mass%) 0.38 parts by mass

[0174] Next, the pressure-sensitive adhesive composition was applied to a release-treated surface of a 50 μm-thick PET separator ("PET50x1-J2" manufactured by Nippa Corporation) so that the thickness after drying would be 65 μm, and then dried to form an adhesive layer. Thereafter, the laminate of the separator and adhesive layer was laminated onto one side of the protective layer to obtain a protective film.

[0175] Example 2 First, a protective layer was formed in the same manner as in Production Example A1.

[0176] The following components were mixed to prepare a pressure-sensitive adhesive composition. <Adhesive composition> Adhesive: (meth)acrylic acid alkyl ester copolymer (Nippon Carbide Industries Co., Ltd. "Nissetsu KP-2610", solid content: 45 mass%, solvent: methyl ethyl ketone, ethyl acetate) 100 parts by mass Crosslinking agent: isocyanate group-terminated urethane resin (Nippon Carbide Industries Co., Ltd. "Nissetsu CK-121", solid content: 10 mass%, solvent: methyl ethyl ketone) 0.2 parts by mass Silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM-403", solid content: 100 mass%) 0.23 parts by mass Phenolic antioxidant (ADEKA Corporation "ADK STAB AO-60G", solid content: 100 mass%) 0.57 parts by mass Ultraviolet absorber (ADEKA Corporation "ADK STAB LA-24", solid content: 100 mass%) 0.57 parts by mass

[0177] Next, the pressure-sensitive adhesive composition was applied to a release-treated surface of a 50 μm-thick PET separator ("PET50x1-J2" manufactured by Nippa Corporation) so that the thickness after drying would be 65 μm, and then dried to form an adhesive layer. Thereafter, a laminate of the separator and adhesive layer was laminated onto one side of the protective layer and aged at 50°C for 3 days. This resulted in a protective film.

[0178] Example 3 First, a protective layer was formed in the same manner as in Production Example A2. Next, a protective film was obtained in the same manner as in Example 1.

[0179] Example 4 First, a protective layer was formed in the same manner as in Production Example A2. Then, a protective film was obtained in the same manner as in Example 2.

[0180] Example 5 First, a protective layer was formed in the same manner as in Production Example A3. Then, a protective film was obtained in the same manner as in Example 1.

[0181] Comparative Example 1 First, a protective layer was produced in the same manner as in Production Example B3. Next, a protective film was obtained in the same manner as in Example 1.

[0182] Comparative Example 2 First, a protective layer was produced in the same manner as in Production Example B3. Next, a protective film was obtained in the same manner as in Example 2.

[0183] Example 6 First, a protective layer was formed in the same manner as in Production Example A3. Next, a protective film was obtained in the same manner as in Example 2.

[0184] [Evaluation 2] (1) Adhesion to SUS Plate The adhesion of the protective film to the SUS plate was measured by the method described above in "A. Protective film for blades of wind turbine generator 4. Physical properties of the protective film (1) Adhesion".

[0185] (2) Adhesion to Fluororesin Layer The adhesion of the protective film to the fluororesin layer was measured by the method described above in "A. Protective film for blades of wind turbine generator, 4. Physical properties of protective film, (1) Adhesion."

[0186] (3) Tensile Load at 10% Elongation The tensile load at 10% elongation of the protective layer was measured by the method described above in "A. Protective film for blades of wind turbine generator 4. Physical properties of protective film (1) Adhesion strength".

[0187] (4) Lifting and peeling at 10% elongation A test plate used to measure the adhesive strength to the fluororesin layer was prepared. A protective film was cut into a width of 10 mm and a length of 50 mm. The protective film was attached to the fluororesin layer side of the test plate in a state where it was elongated by 10% in the length direction, and stored at 25°C and 50% RH for 24 hours. Thereafter, the state of the protective film was visually observed. Lifting and peeling were evaluated according to the following criteria. A: No lifting or peeling B: Lifting or peeling

[0188]

[0189] From Table 5, it can be seen that when the adhesive strength of the protective film to the fluororesin layer is equal to or greater than the tensile load at 10% elongation of the protective layer, there is no lifting or peeling at 10% elongation, and durability is excellent.

[0190] [Examples 7 to 9] Protective films were produced in the same manner as in Example 1. In this case, in forming the protective layer, the speed of the take-up roll during film formation was changed in order to adjust the thickness uniformity of the protective layer. By increasing the speed of the take-up roll, thinner portions were obtained.

[0191] [Evaluation 3] (1) Thickness uniformity The thickness of the protective film was measured by the method described above in "A. Protective film for blades of wind turbine generators 4. Physical properties of the protective film (4) Thickness uniformity." In this case, the size of the protective film was 30 cm vertically and 20 cm horizontally, and the thickness of the protective film was measured at 10 positions at 3 cm intervals in the vertical direction and at 10 positions at 2 cm intervals in the horizontal direction. Next, the minimum thickness of the protective film was determined when the maximum thickness of the protective film was taken as 100%.

[0192] (2) Durability Test A durability test was carried out on the protective film in the same manner as in (11) Durability Test of Evaluation 1 above, and the state of the protective film after the durability test was visually observed. The state of the protective film was evaluated according to the following criteria: A: No change from the initial state B: Changes such as cracks were observed compared to the initial state

[0193]

[0194] From Table 6, it can be seen that the more uniform the thickness of the protective film, the more excellent the durability.

[0195] The present disclosure provides the following inventions. [1] A protective film for a blade of a wind power generator, comprising a protective layer containing a polyolefin resin and an adhesive layer disposed on one side of the protective layer, wherein the tensile modulus of the protective layer is 5 MPa or more and 35 MPa or less. [2] The protective film for a blade according to [1], wherein the protective layer has a tensile stress at break of 5 MPa or more. [3] The protective film for a blade according to [1] or [2], wherein the protective layer has a tensile elongation at break of 800% or more. [4] The protective layer has a unit weight of 40 g / m ２ 900g / m or more ２ [5] The protective film for a blade according to any one of [1] to [3], wherein the water vapor permeability of the protective layer is 15.0 g / (m ２24h) or less. [6] The blade protective film according to any one of [1] to [5], having an adhesive strength to an SUS plate of 3 N / 10 mm or more. [7] The blade protective film according to any one of [1] to [6], having an adhesive strength to a fluororesin layer of 2.5 N / 10 mm or more. [8] The blade protective film according to any one of [1] to [7], having a minimum thickness of the blade protective film of 80% or more when the maximum thickness of the blade protective film is 100%. [9] A blade for a wind power generator having on its surface the blade protective film according to any one of [1] to [8].

[10] A wind power generator comprising the blade according to [9].

[0196] REFERENCE SIGNS LIST 1: protective layer 2: adhesive layer 10: protective film 20: blade 30: wind power generator

Claims

1. A protective film for wind power generation device blades, comprising a protective layer containing a polyolefin resin and an adhesive layer disposed on one side of the protective layer, the tensile modulus of the protective layer being 5 MPa or more and 35 MPa or less.

2. The protective film for blades according to claim 1, wherein the protective layer has a tensile breaking stress of 5 MPa or more.

3. The protective film for blades according to claim 1, wherein the protective layer has a tensile elongation at break of 800% or more.

4. The unit weight of the protective layer is 40 g / m ２ 900g / m or more ２ 2. The protective film for blades according to claim 1, wherein:

5. The water vapor permeability of the protective layer is 15.0 g / (m ２ The protective film for blades according to claim 1, wherein the hardness is 24 h or less.

6. The protective film for blades according to claim 1, which has an adhesive strength to a stainless steel plate of 3 N / 10 mm or more.

7. The protective film for blades according to claim 1, which has an adhesive strength to the fluororesin layer of 2.5 N / 10 mm or more.

8. The blade protection film according to claim 1, wherein the minimum thickness of said blade protection film is 80% or more when the maximum thickness of said blade protection film is 100%.

9. A blade for a wind turbine generator having a blade protective film according to any one of claims 1 to 8 on its surface.

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

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