Coating film for aircraft and method for manufacturing coating film for aircraft

Abstract

To clean an aircraft body to remove stains on it such as insects efficiently and effectively and with reduced environmental load.SOLUTION: A coating film for aircraft has: a photocatalyst layer laminated on a base material; and a polymer brush layer that includes polymer brushes provided at intervals on the photocatalyst layer, and grooves defined by the polymer brushes and the photocatalyst layer, the polymer brush layer exposed to the atmosphere.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a coating film for an aircraft and a method for producing a coating film for an aircraft. [Background technology]

[0002] During flight, dirt (dust, oil, insects, etc.) adheres to the surface of the aircraft. Insects are particularly likely to collide with the leading edges of the wings and adhere to them during flight. When insects adhere to the aircraft's airframe, they increase frictional resistance during flight, which can result in poor fuel efficiency. Therefore, in order to improve fuel efficiency, prevent corrosion, and maintain aesthetics, the aircraft is periodically washed to remove dirt that has adhered to the surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-236459 [Non-patent literature]

[0004] [Non-Patent Document 1] Goro Kondo and Sadayasu Nakai, "Problems with Aircraft Hull Cleaning," Environmental Technology, Environmental Technology Society, April 1986, Vol. 15, No. 4, pp. 343-348 Summary of the Invention [Problem to be solved by the invention]

[0005] Typically, every one to two months, 10 to 20 people per aircraft spend several hours manually cleaning the fuselage using deck brushes, etc. This method is not only time-consuming and labor-intensive, but also requires large amounts of cleaning agent (a weak alkaline water-based cleaning agent mixed with kerosene depending on the level of contamination) and water (around 20 tons), which places a heavy burden on the environment due to the wastewater from the cleaning process.

[0006] The dry wash method is also known. In this method, a sticky, water-soluble detergent is manually applied to the aircraft surface to dissolve the oil and dirt adhering to the surface, which is then wiped away by hand with a microfiber cloth. This method is time-consuming and labor-intensive, requiring 10 to 20 people to perform the process per aircraft for 9 to 12 hours, approximately three times a year.

[0007] As an alternative to these methods, methods for cleaning aircraft fuselages, such as the automatic moving brush method, the octopus cleaning method, and the foam cleaning method, have been proposed (Non-Patent Document 1). With the automatic moving brush method, a cleaning unit is slid over the surface of the fuselage according to the fuselage shape stored in a computer to clean the fuselage. With the octopus cleaning method, detergent is sprayed onto the surface of the fuselage, and then a mixture of high-pressure air and water droplets is sprayed onto the surface to clean it. With the foam cleaning method, detergent made into a foam by adding a thickener is attached to the fuselage, and then the fuselage is washed with water.

[0008] However, the automatic moving brush method requires a large initial investment to memorize the shape of each aircraft, is difficult to clean in fine detail, and requires updating the shape of the aircraft to correct the cleaning position when the aircraft (mainly the main wings) undergoes thermal deformation (expansion and contraction).The foam cleaning method generates wastewater that places a heavy burden on the environment.For these reasons, these methods have not yet been put into practical use.

[0009] In view of the above circumstances, an object of the present invention is to efficiently and effectively clean dirt such as insects adhering to the body of an aircraft while minimizing the environmental impact. [Means for solving the problem]

[0010] The coating film for aircraft according to the present invention comprises a photocatalyst layer laminated on a base material, a plurality of polymer brushes provided on the photocatalyst layer and spaced apart from one another, and a polymer brush layer having a plurality of grooves defined by the plurality of polymer brushes and the photocatalyst layer and exposed to the atmosphere. According to the present invention, adhered dirt can be easily removed, and an increase in frictional resistance during flight can be suppressed, thereby suppressing a decrease in fuel efficiency.

[0011] The photocatalytic layer is hydrophilic, and at least some of the grooves are capable of communicating with one another. According to the present invention, the aircraft body can be washed with water, which reduces the environmental impact.

[0012] Adjacent polymer brushes are spaced apart on the order of millimeters. Such polymer brushes are produced using a patterning sheet having a shape in which adjacent polymer brushes are spaced apart on the order of millimeters. According to the present invention, various millimeter-order patterning sheets can be produced according to needs, thereby producing various millimeter-order polymer brushes.

[0013] The size of each of the multiple polymer brushes is on the order of millimeters. Such polymer brushes are produced using a patterning sheet having a shape in which each of the multiple polymer brushes has a size on the order of millimeters. According to the present invention, by producing various patterning sheets on the order of millimeters according to needs, it is possible to produce various polymer brushes on the order of millimeters.

[0014] Each of the plurality of polymer brushes is exposed to the atmosphere and has a polymer brush surface with a nano-order structure. According to the present invention, since the polymer brush surface has a nano-order structure, it is possible to effectively remove dirt.

[0015] The photocatalytic layer is exposed to the atmosphere through a plurality of grooves and has a photocatalytic surface with a micro-order structure. According to the present invention, since the photocatalytic surface has a micro-order structure, it is possible to effectively remove dirt.

[0016] The photocatalyst layer is exposed to the atmosphere through a plurality of grooves and includes micro-order resin capsules to which a photocatalyst is attached. According to the present invention, since the photocatalyst layer includes resin capsules to which a photocatalyst is attached, a large number of photocatalysts are exposed from the photocatalyst surface, improving the photocatalytic effect.

[0017] The base material is at least a part of the aircraft fuselage, including the leading edge of the main wing. According to the present invention, dirt adhering to the leading edge of the main wing is easily removed, thereby suppressing an increase in frictional resistance during flight and suppressing a decrease in fuel efficiency.

[0018] The base material is a sheet material that can be adhered to at least a portion of the aircraft fuselage. According to the present invention, various portions of the aircraft fuselage can be coated with the aircraft coating film according to needs.

[0019] The method for producing a coating film for an aircraft according to the present invention comprises the steps of: A photocatalytic layer is laminated on the base material, a patterning sheet, which is peelable from the photocatalyst layer and has a sheet body and a plurality of through holes spaced apart from each other, laminated on the photocatalyst layer; a polymerization initiator layer is deposited in the plurality of through holes; After a predetermined time has elapsed, the patterning sheet is peeled off, a film-forming layer is attached onto the photocatalyst layer and the patterned polymerization initiator layer; a release sheet is tightly adhered to and laminated on the film-forming layer to create a vacuum state in the film-forming layer, thereby forming a laminate; growing a plurality of polymer brushes on the polymerization initiator layer; After a predetermined time has elapsed, the release sheet is peeled off from the laminate; The film layer that was covered with the release sheet is removed from the laminate, A coating film for an aircraft is manufactured, which includes the photocatalyst layer, the plurality of polymer brushes provided on the photocatalyst layer and spaced apart from one another, and a polymer brush layer exposed to the atmosphere, the polymer brush layer having a plurality of grooves defined by the plurality of polymer brushes and the photocatalyst layer. [Effects of the Invention]

[0020] According to the present invention, dirt such as insects adhering to the body of an aircraft can be cleaned efficiently and effectively with a low environmental impact.

[0021] The effects described here are not necessarily limited to those described above, and may be any of the effects described in the present invention. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a perspective view schematically illustrating a fuselage of an aircraft according to an embodiment of the present invention. [Figure 2] FIG. 1 is a perspective view schematically showing a coating film for an aircraft. [Figure 3] 1 shows a schematic diagram of the structure of a photocatalytic layer. [Figure 4] The structure of an aircraft coating film is shown schematically. [Figure 5] 1 shows a schematic diagram of a method for producing a coating film for an aircraft. [Figure 6] 1 shows a schematic diagram of a patterning sheet. [Figure 7] The evaluation test results are shown below. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] 1. Aircraft Overview

[0025] FIG. 1 is a perspective view that schematically shows the fuselage of an aircraft according to one embodiment of the present invention.

[0026] The airframe of the aircraft 1 includes a fuselage 2, a tail 3, and a pair of main wings 4. When the aircraft 1 is in flight, dirt (dust, oil, insects, etc.) adheres to the surface of the airframe. In particular, insects are likely to collide with and adhere to the leading edges 5 of the main wings 4 during flight. When insects adhere to the airframe of the aircraft, the attached insects increase frictional resistance during flight of the aircraft 1, which may result in poor fuel efficiency.

[0027] In consideration of the above circumstances, the aircraft 1 according to this embodiment has an aircraft coating film applied to at least a portion of the fuselage of the aircraft 1, including at least the leading edges 5 of the pair of main wings 4. In other words, the aircraft coating film may be applied to the entire fuselage of the aircraft 1, or only to at least the leading edges 5 of the pair of main wings 4, or alternatively, the aircraft coating film may be applied to at least the leading edges 5 of the pair of main wings 4 and another surface of the fuselage of the aircraft 1. The aircraft coating film has the property of making it easy to remove adhering dirt (dust, oil, insects, etc.).

[0028] In this embodiment, the "leading edge 5 of the main wing 4" refers to any region of the main wing 4 including the leading edge 5, and may include, for example, a Krueger flap.

[0029] 2. Structure of aircraft coating film

[0030] FIG. 2 is a perspective view schematically showing a coating film for an aircraft.

[0031] The aircraft coating film 100 has a photocatalyst layer 20 laminated on a base material 10 and a polymer brush layer 30 laminated on the photocatalyst layer 20 .

[0032] The base material 10 is typically at least a portion of the fuselage of the aircraft 1, including at least the leading edges 5 of the pair of main wings 4. In other words, the base material 10 may be the entire surface of the fuselage of the aircraft 1, or may be only at least the leading edges 5 of the pair of main wings 4, or may be at least the leading edges 5 of the pair of main wings 4 and another surface of the fuselage of the aircraft 1. Alternatively, the base material 10 may be a sheet material that can be adhered to at least a portion of the fuselage of the aircraft 1 (more specifically, at least the leading edges 5 of the pair of main wings 4).

[0033] 2-1. Structure of the photocatalytic layer

[0034] FIG. 3 shows a schematic diagram of the structure of the photocatalytic layer.

[0035] The photocatalyst layer 20 is exposed to the atmosphere via a plurality of grooves (grooves 32 described below), has a photocatalytic surface 25 with a micro-order structure, and is hydrophilic. The photocatalyst layer 20 includes microcapsules 22 blended into a paint 21. The microcapsules 22 are micro-order resin capsules 24 with photocatalysts 23 attached thereto. The photocatalysts 23 are attached without gaps so as to cover the surfaces of the resin capsules 24. The thickness of the photocatalyst layer 20 is 80 to 100 μm.

[0036] The paint 21 includes a highly durable and hydrophilic material (eg, colloidal silica).

[0037] The resin capsule 24 is, for example, a spherical resin having a diameter of approximately 30 to 50 μm. The surface and interior of the resin capsule 24 may be made of the same resin material, or may be made of different resin materials. Alternatively, the resin capsule 24 may have a hollow structure in which the surface of the sphere is made of a resin material and the interior is filled with gas or vacuum.

[0038] The photocatalyst 23 is, for example, nanometer-sized titanium oxide. Here, nanometer size refers to a diameter of 1 nm or more and 1000 nm or less, and the diameter is, for example, 2 nm or more, 3 nm or more, 4 nm or more, 5 nm or more, 7 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, and 9 nm or less, 10 nm or less, 15 nm or less, 20 nm or less, 30 nm or less, 50 nm or less, 70 nm or less, 100 nm or less, 300 nm or less, 500 nm or less, and 700 nm or less. Typically, the photocatalyst 23 is titanium oxide with a diameter of 1 to 20 nm. When exposed to sunlight, the photocatalyst 23 generates powerful active oxygen called oxygen radicals on its surface.

[0039] If the photocatalyst 23 were to be blended directly into the paint 21 (without being attached to the resin capsules 24), the photocatalyst 23 would be blended uniformly into the paint 21, resulting in a limited number of photocatalysts 23 exposed on the surface of the paint 21 (not shown). In contrast, if microcapsules 22 with photocatalysts 23 attached to the resin capsules 24 are blended into the paint 21, the microcapsules 22 would be exposed unevenly from the photocatalytic surface 25, which is the surface of the paint 21 (the area surrounded by ellipse A in the figure). Because the exposed surface of the microcapsules 22 is covered with the photocatalyst 23, many of the photocatalysts 23 are exposed to the atmosphere, improving the photocatalytic effect. When sunlight hits the photocatalytic surface 25 with dirt (dust, oil, etc.) attached, the photocatalyst 23 acts to decompose organic matter.

[0040] 2-2. Polymer brush layer structure

[0041] FIG. 4 shows a schematic diagram of the structure of a coating film for aircraft.

[0042] The polymer brush layer 30 has multiple polymer brushes 31 and multiple grooves 32 and is exposed to the atmosphere. Each of the multiple polymer brushes 31 has a polymer brush surface 35. The polymer brush surface 35 is exposed to the atmosphere and has a nano-order structure. The polymer brush surface 35 has a variety of surface properties (liquid repellency, low friction, low biomolecule adhesion, stimuli responsiveness, anti-aggregation properties between nanomaterials, adhesiveness, etc.) due to the three-dimensional structure of the multiple polymer brushes 31. The thickness of the polymer brush layer 30 is 20 to 100 nm.

[0043] The multiple polymer brushes 31 are provided on the photocatalytic surface 25 of the photocatalytic layer 20 and are spaced apart from one another. The multiple adjacent polymer brushes 31 are spaced apart on the order of millimeters. For example, the distance between adjacent polymer brushes 31 is 1 mm to 5 mm. The size of each of the multiple polymer brushes 31 is on the order of millimeters. For example, the size of each polymer brush 31 is a square measuring 5 mm x 5 mm.

[0044] The multiple grooves 32 are spaces defined by the multiple polymer brushes 31 and the photocatalytic layer 20. At least some of the multiple grooves 32 can communicate with each other. In the example of FIG. 2, the multiple grooves 32 can communicate with each other in a lattice pattern (two directions). Alternatively, the multiple grooves 32 may be able to communicate with each other in another shape (for example, stripes (one direction)) (not shown).

[0045] Each of the plurality of polymer brushes 31 includes a polymerization initiator layer 33 and a brush layer 34 .

[0046] The polymerization initiator layer 33 is a thin film layer that serves as the starting point for a polymerization reaction (a reaction in which a large number of repeating units of low molecular weight (monomers) are linked together to produce a polymer). The polymerization initiator layer 33 contains an organosilane (trialkoxysilane) having a polymerization initiation group (a functional group that serves as the starting point for a polymerization reaction) and a tetraalkoxysilane. The polymerization initiator layer 33 is produced, for example, by a reaction represented by chemical formula (1). CMPTMS (p-chloromethylphenyl trimethoxysilane) is an example of a trialkoxysilane, and TEOS (tetraethoxysilane) is an example of a tetraalkoxysilane.

[0047] [ka]

[0048] The brush layer 34 is produced by growth through a polymerization reaction starting from the polymerization initiator layer 33. The brush layer 34, in which polymers extend from the polymerization initiator layer 33, has excellent durability and stability because the polymers (brush layer 34) and the polymerization initiator layer 33 are directly bonded to each other. The brush layer 34 is produced so as to be directly bonded to the polymerization initiator layer 33, for example, through a reaction represented by chemical formula (2). In chemical formula (2), PMDETA represents N,N,N',N'',N''-Pentamethyldiethylenetriamine, and SPMK represents 3-sulfopropyl methacrylate potassium salt. Instead of SPMK, AMPSNa (2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt) or PEGMA (poly(ethylene glycol) methacrylate) may also be used for the brush layer 34.

[0049] [ka]

[0050] 3. Manufacturing method for aircraft coating films

[0051] FIG. 5 shows a schematic diagram of a method for producing a coating film for an aircraft.

[0052] Step S1: Prepare a base material 10. The base material 10 is typically at least a portion of the fuselage of the aircraft 1, including at least the leading edges 5 of the pair of main wings 4. In other words, the base material 10 may be the entire surface of the fuselage of the aircraft 1, or may be only at least the leading edges 5 of the pair of main wings 4, or may be at least the leading edges 5 of the pair of main wings 4 and another surface of the fuselage of the aircraft 1. Alternatively, the base material 10 may be a sheet material that can be adhered to at least a portion of the fuselage of the aircraft 1 (more specifically, at least the leading edges 5 of the pair of main wings 4).

[0053] Step S2: The photocatalyst layer 20 is laminated on the base material 10. Specifically, the photocatalyst 23 is attached to a resin capsule 24 in advance to produce a microcapsule 22, and the microcapsule 22 is mixed with a paint 21. The paint 21 mixed with the microcapsules 22 is applied to the base material and solidified by drying. In this way, the photocatalyst layer 20 is produced.

[0054] Step S3: After laminating the patterning sheet 40 on the photocatalyst layer 20, the polymerization initiator layer 33 is adhered. Specifically, a polymerization initiator is produced in advance by mixing an organosilane (trialkoxysilane) having a polymerization initiator group (a functional group that serves as the starting point for a polymerization reaction) and a tetraalkoxysilane with a catalyst, water, and alcohol. The polymerization initiator (which becomes the polymerization initiator layer 33 when solidified) is applied to the photocatalyst layer 20. The thickness (height) of the polymerization initiator layer 33 is several tens of nanometers.

[0055] Step S4: The patterning sheet 40 is peeled off. This forms a patterned polymerization initiator layer 33 on the photocatalyst layer 20. The patterning sheet 40 can be peeled off from the photocatalyst layer 20.

[0056] FIG. 6 shows a schematic diagram of a patterning sheet.

[0057] The patterning sheet 40 has a sheet body 42 and a plurality of through holes 41 spaced apart from one another. A plurality of polymerization initiator layers 33 are formed in each of the plurality of through holes 41. Grooves 32 are formed in the sheet body 42 (the portion not including the through holes 41) of the patterning sheet 40. Therefore, the patterning sheet 40 has a shape corresponding to the shape of the polymer brush layer 30. That is, the patterning sheet 40 has a shape in which at least some of the grooves 32 can communicate with each other (in other words, the sheet body 42 (the portion not including the through holes 41) has a shape in which the plurality of adjacent polymer brushes 31 are spaced apart on the order of millimeters (in other words, the plurality of adjacent through holes 41 are spaced apart on the order of millimeters). The patterning sheet 40 has a shape in which the size of each of the plurality of polymer brushes 31 is on the order of millimeters (in other words, the size of each of the plurality of through holes 41 is on the order of millimeters). For example, the size of the through holes 41 is 5 mm×5 mm, and the intervals are 1 mm to 5 mm. The thickness (height) of the patterning sheet 40 is, for example, 50 μm.

[0058] Step S5: A solution prepared by adding 2.1 g of SPMK, 2.8 mg of CuCl2, and 10 μL of PMEDTA to 8 mL of water and 10 mg of ascorbic acid and stirring is applied to the photocatalyst layer 20 and the polymerization initiator layer 33 and allowed to react at room temperature for 2 hours. This produces a film layer 36 on the surface of the photocatalyst layer 20 and the patterned polymerization initiator layer 33. Note that the scale of the reaction varies depending on the application area, so the above reaction time is an example.

[0059] Step S6: The release sheet 50 is tightly adhered to the film-forming layer 36 and laminated to produce a laminate 60. The release sheet 50 is, for example, a PET (polyethylene terephthalate) sheet. This creates a vacuum between the film-forming layer 36 and the release sheet 50. Under vacuum conditions, oxygen permeation into the film-forming layer 36 is suppressed, and the polymerization reaction of the film-forming layer 36 becomes active.

[0060] Step S7: The laminate 60 is left for a predetermined time (approximately 2 hours), whereby the brush layer 34 grows by a polymerization reaction starting from the polymerization initiator layer 33. This produces a plurality of polymer brushes 31, each including a polymerization initiator layer 33 and a brush layer 34.

[0061] Step S8: After a predetermined time (about 2 hours) has elapsed, the release sheet 50 is peeled off from the laminate 60.

[0062] Step S9: The laminate 60 from which the release sheet 50 has been removed is washed with water. This removes the film formation layer 36 that was covered with the release sheet 50 from the laminate 60, i.e., the portion on which the polymerization initiator layer 33 is not formed. This produces the polymer brush layer 30. The polymer brush layer 30 has a plurality of polymer brushes 31 that are spaced apart and provided on the photocatalyst layer 20, and a plurality of grooves 32 defined by the plurality of polymer brushes 31 and the photocatalyst layer 20, and is exposed to the atmosphere. This produces an aircraft coating film 100 that includes the photocatalyst layer 20 and the polymer brush layer 30.

[0063] Instead of the above manufacturing method, aircraft coating films can also be manufactured using screen printing technology. Specifically, the process is as follows: A substrate 10 is prepared, a photocatalyst layer 20 is laminated on the substrate 10, and a screen sheet (not shown) is then attached to the substrate. The screen sheet has multiple through-holes (e.g., 1 mm x 1 mm squares) formed in it by screen printing. A polymerization initiator layer 33 is attached to the photocatalyst layer 20 (steps S1 to S3). The polymerization initiator layer 33 is formed by rubbing hexane or base oil Durasyn (registered trademark) containing 1% silane coupling agent onto the photocatalyst layer 20. The screen sheet is then removed, creating a patterned polymerization initiator layer 33. A solution of SPMK, CuCl2, PMEDTA, water, and ascorbic acid is stirred and applied to the photocatalyst layer 20 and the polymerization initiator layer 33. A release sheet 50 is then attached to the deposition layer 36, and the resulting layer is left for a predetermined time (approximately 2 hours). This allows the brush layer 34 to grow due to the polymerization reaction of the deposition layer 36. This produces multiple polymer brushes 31, each including a polymerization initiator layer 33 and a brush layer 34. The polymerization initiator layer 33 and the brush layer 34 are washed with water, thereby removing the areas where the polymer brushes 31 are not formed. This produces the polymer brush layer 30. A finer mesh can be produced by using screen printing technology.

[0064] 4. First Experimental Example

[0065] A model of a Krueger flap coated with aircraft coating film 100 was produced. For comparison, a model of a Krueger flap coated with an existing coating film was produced. Each model was mounted on the roof of a vehicle. Each vehicle was driven on a test circuit in an insect-filled environment.

[0066] After the run, the number of insects attached to each model (total number of insects) was counted. Each model was then washed with water from a shower for 20 seconds. After washing, the number of insects that had detached from each model (number of insects washed) was counted. The washing rate (number of insects washed / total number of insects) (%) was calculated. The above evaluation test was carried out three times.

[0067] FIG. 7 shows the results of the evaluation test.

[0068] It can be seen that the cleaning rate of the aircraft coating film 100 is improved by about 10% compared to the existing coating film.

[0069] 5. Second Experimental Example

[0070] Three types of test specimens were prepared: (1) existing coating film, (2) a test specimen with polymer brushes 31 grown on the entire surface of the photocatalytic paint (photocatalytic paint + full-surface polymer brush), and (3) a test specimen with polymer brushes 31 grown on a portion (mesh-like) of the photocatalytic paint (photocatalytic paint + mesh-like polymer brush). Each of the three test specimens measured 10 cm x 10 cm. Twenty insects (1-2 mm in size) were manually attached to each of the three test specimens, and the specimens were washed with water at a constant flow rate for a set period of time. The washing conditions were a flow rate of 11.8 L / min, a washing time of 30 seconds, and a distance of 200 mm between the test specimen and the shower head. After washing, the number of insects detached from each test specimen (number of insects washed) was counted. The washing rate (number of insects washed / total number of attached insects [%]) was calculated. Each of the above evaluation tests was conducted 10 times.

[0071] The cleaning rate for (1) the conventional coating film was 58.7%, (2) the cleaning rate for photocatalytic paint + full-surface polymer brush was 76.5%, and (3) the cleaning rate for photocatalytic paint + mesh polymer brush was 79%. (3) The cleaning rate for photocatalytic paint + mesh polymer brush was approximately 20% higher than that for (1) the conventional coating film. (3) The cleaning rate for photocatalytic paint + mesh polymer brush was 2.5% higher than that for (2) the photocatalytic paint + full-surface polymer brush. (3) The photocatalytic paint + mesh polymer brush has an uneven surface, while (2) the photocatalytic paint + full-surface polymer brush has no uneven surface. For this reason, it is thought that the uneven surface is effective in improving cleaning rate.

[0072] 6. Conclusion

[0073] The aircraft coating film 100 according to this embodiment includes a photocatalytic layer 20 laminated on a base material 10, a plurality of polymer brushes 31 provided on the photocatalytic layer 20 and spaced apart from one another, and a plurality of grooves 32 defined by the plurality of polymer brushes 31 and the photocatalytic layer 20, and the polymer brush layer 30 is exposed to the atmosphere.

[0074] As described above, the polymer brush layer 30 has multiple polymer brushes 31 spaced apart from one another. Due to the presence of grooves 32 between adjacent polymer brushes 31, insects that collide with the aircraft 1's airframe do not adhere to the entire surface but instead straddle the multiple polymer brushes 31 via the grooves 32. This allows the insects to more easily detach from the polymer brushes 31 than if the insects were to adhere to the entire surface. Furthermore, when dirt (oil, dust, etc.) adheres to the photocatalytic layer 20 via the grooves 32, sunlight irradiating the photocatalytic surface 25 activates the photocatalyst 23, decomposing the organic matter contained in the dirt. Thus, small dirt (oil, dust, etc.) that has entered the grooves 32 is decomposed by the action of the photocatalyst 23, while large dirt (insects, etc.) adheres to the multiple polymer brushes 31 and is easily detached. Therefore, the aircraft coating film 100 effectively detaches both small dirt (oil, dust, etc.) and large dirt (insects, etc.). Because small dirt (oil, dust, etc.) has already been decomposed by the photocatalyst 23, it is easily detached from the photocatalytic surface 25. If dirt (dust, oil, insects, etc.) adheres to the surface of the aircraft 1's airframe (particularly the leading edges of the main wings), the adhered dirt may increase frictional resistance during flight, resulting in poor fuel efficiency. In contrast, according to this embodiment, the adhered dirt is easily peeled off, which makes it possible to suppress an increase in frictional resistance during flight and suppress a decrease in fuel efficiency.

[0075] According to this embodiment, the photocatalytic layer 20 is hydrophilic, and at least some of the grooves 32 can communicate with each other.

[0076] As described above, the multiple grooves 32 are defined by the hydrophilic photocatalytic layer 20, and at least some of the multiple grooves 32 can communicate with one another. Therefore, when removing dirt from the aircraft 1's fuselage, the fuselage can be washed with water without using detergent. Because the photocatalytic layer 20 defining the multiple grooves 32 is hydrophilic, when water is sprayed on the aircraft 1's fuselage, the water flows between the multiple grooves 32. As a result, water penetrates between the hydrophilic photocatalytic surface 25 defining the grooves 32 and small dirt (oil, dust, etc.) attached to the photocatalytic surface 25 (already decomposed by the photocatalyst 23), causing the small dirt (oil, dust, etc.) to peel off from the photocatalytic surface 25. At the same time, because water flows between the multiple grooves 32, large dirt (insects) attached to the multiple polymer brushes 31 across the grooves 32 also peel off. This allows for effective removal of both small dirt (oil, dust, etc.) and large dirt (insects, etc.). Furthermore, simply washing the aircraft 1's fuselage with water reduces the environmental impact.

[0077] According to this embodiment, the adjacent polymer brushes 31 are spaced apart on the order of millimeters. Such polymer brushes 31 are fabricated using a patterning sheet 40 having a shape in which the adjacent polymer brushes 31 are spaced apart on the order of millimeters.

[0078] By producing various millimeter-order patterned sheets 40 according to needs, it is possible to produce various millimeter-order polymer brushes 31. For example, in an aircraft coating film 100 used for aircraft 1 that frequently operates in areas where large insects are common, the spacing between adjacent polymer brushes 31 is wide. As a result, the narrow spacing between adjacent polymer brushes 31 prevents large insects from adhering to the polymer brushes 31 in a planar manner, and the large insects adhere to the polymer brushes 31 by straddling them via the grooves 32. Conversely, in an aircraft coating film 100 used for aircraft 1 that frequently operates in areas where small insects are common, the spacing between adjacent polymer brushes 31 is narrow. As a result, the wide spacing between adjacent polymer brushes 31 prevents small insects from entering the grooves 32, and the small insects adhere to the polymer brushes 31 by straddling them via the grooves 32.

[0079] According to this embodiment, the size of each of the plurality of polymer brushes 31 is on the order of millimeters. Such polymer brushes 31 are produced using a patterning sheet 40 having a shape in which the size of each of the plurality of polymer brushes 31 is on the order of millimeters.

[0080] By producing various millimeter-order patterning sheets 40 according to needs, it is possible to produce various millimeter-order polymer brushes 31. For example, the size of the polymer brushes 31 is reduced in the aircraft coating film 100 used for aircraft 1 that frequently operate in areas where many small insects are found. This prevents small insects from adhering to large polymer brushes 31 in a planar manner, and small insects are able to adhere to multiple polymer brushes 31 by straddling them via the grooves 32.

[0081] According to this embodiment, each of the plurality of polymer brushes 31 has a polymer brush surface 35 that is exposed to the atmosphere and has a nano-order structure.

[0082] Because the polymer brush surface 35 has a nano-order structure, large dirt (insects, etc.) is more easily peeled off from the polymer brush surface 35 than if the polymer brush surface had a flatter surface and large dirt (insects, etc.) would stick to it, and large dirt (insects, etc.) can be effectively peeled off.

[0083] According to this embodiment, the photocatalytic layer 20 is exposed to the atmosphere through a plurality of grooves 32 and has a photocatalytic surface 25 having a micro-order structure.

[0084] Since the photocatalytic surface 25 has a micro-order structure, small stains (oil, dust, etc.) are more easily peeled off from the photocatalytic surface 25 than if the photocatalytic surface had a flatter surface and small stains (oil, dust, etc.) stuck to it, and the small stains (oil, dust, etc.) can be effectively peeled off.

[0085] According to this embodiment, the photocatalyst layer 20 is exposed to the atmosphere through a plurality of grooves 32 and includes micro-order resin capsules 24 to which photocatalysts 23 are attached.

[0086] If the photocatalyst 23 were blended directly into the paint 21 (without being attached to the resin capsules 24), the photocatalyst 23 would be blended uniformly into the paint 21, and the number of photocatalysts 23 exposed on the surface of the paint 21 would be limited. In contrast, when the photocatalyst layer 20 includes the resin capsules 24 to which the photocatalyst 23 is attached, the photocatalyst 23 is exposed non-uniformly from the photocatalytic surface 25. Since many of the exposed photocatalysts 23 are exposed to the atmosphere, the photocatalytic effect is improved.

[0087] According to this embodiment, the base material 10 is at least a part of the fuselage of the aircraft 1 , including the leading edge 5 of the wing 4 .

[0088] If an insect collides with and adheres to the leading edge 5 of the main wing 4 of the aircraft 1 during flight, the attached insect may increase frictional resistance during flight, resulting in poor fuel efficiency. In contrast, according to this embodiment, dirt adhering to the leading edge 5 of the main wing 4 is easily peeled off, thereby suppressing an increase in frictional resistance during flight and suppressing a decrease in fuel efficiency.

[0089] According to this embodiment, the base material 10 is a sheet material that can be adhered to at least a part of the fuselage of the aircraft 1 .

[0090] This allows the aircraft coating film 100 to be coated on various parts of the fuselage of the aircraft 1 according to needs. Also, the aircraft coating film 100 can be replaced at specific intervals (for example, once a year). It is also expected that the aircraft coating film 100 will be used for so-called aircraft wrapping (advertising wrapping).

[0091] Although the embodiments and variations of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0092] 1 :Aircraft 4: Main wing 5: Leading edge 10: Base material 20: Photocatalyst layer 23: Photocatalyst 24: Resin capsule 25: Photocatalytic surface 30: Polymer brush layer 31: Polymer brush 32: Groove 33: Polymerization initiator layer 34: Brush layer 35: Polymer brush surface 36: Film layer 40: Patterning sheet 41: Through hole 50: Peel-off sheet 60: Laminate 100: Aircraft coating film

Claims

1. a photocatalyst layer laminated on a base material and having a photocatalytic surface on which a photocatalyst made of titanium oxide having a diameter of 1 nm or more and 1000 nm or less is unevenly exposed; a polymer brush layer that is exposed to the atmosphere and includes a plurality of polymer brushes that are provided on the photocatalyst layer and are spaced apart from each other, and a plurality of grooves that are defined by the plurality of polymer brushes and the photocatalyst layer; A coating film for an aircraft comprising:

2. The coating film for an aircraft according to claim 1, the photocatalytic layer is hydrophilic; At least some of the grooves are capable of communicating with each other. Coating film for aircraft.

3. The coating film for an aircraft according to claim 1 or 2, The adjacent polymer brushes are spaced apart at intervals of 1 mm to 5 mm. Coating film for aircraft.

4. The coating film for an aircraft according to any one of claims 1 to 3, Each of the polymer brushes has a square shape of 5 mm x 5 mm. Coating film for aircraft.

5. The coating film for an aircraft according to any one of claims 1 to 4, Each of the plurality of polymer brushes has a polymer brush surface exposed to the atmosphere. Coating film for aircraft.

6. An aircraft coating film according to any one of claims 1 to 5, Each of the plurality of polymer brushes has a polymerization initiator layer provided on the photocatalyst layer and a brush layer extending from the polymerization initiator layer. Coating film for aircraft.

7. The coating film for aircraft according to claim 6, The polymerization initiator layer contains an organosilane or tetraalkoxysilane having a polymerization initiator group. Coating film for aircraft.

8. The coating film for an aircraft according to any one of claims 1 to 7, The base material is at least a portion of an aircraft fuselage, including a leading edge of a wing. Coating film for aircraft.

9. The coating film for an aircraft according to any one of claims 1 to 7, The base material is a sheet material that can be adhered to at least a portion of the aircraft fuselage. Coating film for aircraft.

10. A photocatalyst layer having a photocatalytic surface on which a photocatalyst, which is titanium oxide having a diameter of 1 nm or more and 1000 nm or less, is unevenly exposed, is laminated on a base material; a patterning sheet, which is peelable from the photocatalyst layer and has a sheet body and a plurality of through holes spaced apart from each other, laminated on the photocatalyst layer; a polymerization initiator layer is deposited in the plurality of through holes; After a predetermined time has elapsed, the patterning sheet is peeled off, a film-forming layer is attached onto the photocatalyst layer and the patterned polymerization initiator layer; a release sheet is tightly adhered to and laminated on the film-forming layer to create a vacuum state in the film-forming layer, thereby forming a laminate; growing a plurality of polymer brushes on the polymerization initiator layer; After a predetermined time has elapsed, the release sheet is peeled off from the laminate; The film layer that was covered with the release sheet is removed from the laminate, A coating film for an aircraft is manufactured, which comprises the photocatalyst layer having a photocatalytic surface on which a photocatalyst, which is titanium oxide having a diameter of 1 nm or more and 1000 nm or less, is unevenly exposed, the polymer brush layer being provided on the photocatalyst layer and spaced apart from one another, and a polymer brush layer having a plurality of grooves partitioned by the polymer brushes and the photocatalyst layer, and being exposed to the atmosphere. A method for manufacturing aircraft coating films.

11. The method for producing the coating film for an aircraft according to claim 10, The step of growing the plurality of polymer brushes on the polymerization initiator layer includes: and a process for producing the plurality of polymer brushes, each of which includes the polymerization initiator layer and a brush layer grown by a polymerization reaction starting from the polymerization initiator layer, by leaving the laminate for a predetermined time. A method for manufacturing aircraft coating films.

12. The method for producing the coating film for an aircraft according to claim 10 or 11, the photocatalytic layer is hydrophilic; The patterning sheet has a shape that allows at least some of the grooves to communicate with each other. A method for manufacturing aircraft coating films.

13. A method for producing a coating film for an aircraft according to any one of claims 10 to 12, comprising: The patterning sheet has a shape in which the adjacent polymer brushes are spaced apart at intervals of 1 mm to 5 mm. A method for manufacturing aircraft coating films.

14. A method for producing a coating film for an aircraft according to any one of claims 10 to 13, The patterning sheet has a shape in which each of the plurality of polymer brushes has a square shape of 5 mm x 5 mm. A method for manufacturing aircraft coating films.

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