JP2017002269A - Mixed coating material, blade, and ice preventing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixed coating material capable of forming a water-repellent coating film which is reacted and cured at a room temperature and has high durability; and a blade and an ice preventing system capable of efficiently preventing ice.SOLUTION: There are provided a mixed coating material obtained by mixing a room temperature reactive and curable resin and a particulate fluorine resin with a component ratio of the particulate fluorine resin in the coating film of 43 wt.% to 82 wt.%; a blade 110 which has the outermost layer of a water droplet collision area P of a blade front edge portion that is made from a non-water-repellent coating film 112, and has the outermost layer of a water-repellent area Q adjacent to the water droplet collision area P that is formed of a water-repellent coating film 113 formed of the mixed coating material; an ice preventing system 100 having the blade 110 and heating means (heat generation body 120) for heating the water droplet collision area P.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mixed paint, a wing, and a deicing system, and more particularly to a technique useful for deicing a wing of an aircraft or the like.

  In the prior art, an aircraft is provided with an anti-icing device for preventing icing on the fuselage and the growth of icing. This anti-icing device includes an engine bleed or electric thermal deicing device, deisa boots. Pneumatic deicing device by chemical and chemical deicing device by alcohol. The role of aircraft anti-icing equipment is to prevent icing on the aircraft and the growth of icing, to prevent smooth air flow through the aircraft due to icing, and to increase air resistance by reducing wing lift. It is to reduce the wasteful consumption of aircraft fuel during navigation.

  However, in fact, even an aircraft equipped with an anti-icing device has icing in a portion where the icing device cannot completely prevent icing, that is, where the ability of the anti-icing device does not reach. The fact that icing and growing icing cannot be controlled at the part where the capacity of the aircraft's anti-icing device cannot be achieved is because the resistance during navigation increases at the part where the capacity of the anti-icing device cannot be applied, and fuel for useless aircraft. It becomes a big negative factor that leads to consumption.

  In order to solve this problem, it is conceivable that the ice, such as the antenna, flap hinge, control horn, etc., which is not covered by the anti-icing device of the aircraft, can be deiced by adding an anti-icing device or operating the anti-icing device at high operation. . However, trying to apply the deicing effect by the deicing device to the part where the capacity of the deicing device does not reach is due to the increase in the weight of the aircraft due to the addition of the deicing device or the high operation of the deicing device. The current situation is difficult because the consumption of airframe fuel leads to more finite airframe fuel consumption.

  For this reason, it is easy to apply the ice prevention effect to parts of the aircraft that are not covered by the ice prevention device, that is, to the entire surface of the aircraft, and when applied, the weight of the aircraft is small and the fuel during navigation is wasted. In the industry, paints with a high anti-icing effect are craved and studied.

  As such a paint having a high anti-icing effect, a mixed paint capable of forming a highly water-repellent coating film, specifically, for example, an organic resin containing a mixed resin of an ultraviolet curable resin and a tetrafluoroethylene resin, and a hydrofluorocarbon. There has been proposed a mixed paint (hereinafter referred to as “AIS”) having a coating film hardness of 1H or more by mixing with a solvent (see Patent Document 1). A wing structure (anti-icing system) including a wing using AIS as a coating material and a heating unit attached to the wing has been proposed (see Patent Document 2).

Japanese Patent No. 3848334 Japanese Unexamined Patent Publication No. 2010-234989

  However, since AIS is an ultraviolet curable paint, there is a problem that it is difficult to use as a paint for large structures such as aircraft. In addition, a coating film formed by AIS has a problem that durability is low, specifically, water repellency is likely to be lowered by erosion.

  Accordingly, an object of the present invention is to provide a mixed paint capable of forming a highly durable water-repellent coating film that cures at room temperature, a wing capable of efficiently performing deicing, and a deicing system. And

In order to solve the above problem, the invention according to claim 1 is a mixed paint,
A mixture of a room temperature reaction curable resin that cures at room temperature and a particulate fluororesin,
The composition ratio of the particulate fluororesin in the coating film is 43 wt% or more and 82 wt% or less.

The invention described in claim 2 is the mixed paint according to claim 1,
The particulate fluororesin is a tetrafluoroethylene resin.

The invention according to claim 3 is the mixed paint according to claim 1 or 2,
The room temperature reaction curable resin is a fluororesin.

The invention according to claim 4 is the mixed paint according to any one of claims 1 to 3,
The particulate fluororesin has an average particle size of less than 1.5 μm.

The invention according to claim 5 is the mixed paint according to claim 4,
The particulate fluororesin has an average particle size of less than 1.0 μm.

The invention according to claim 6 is the wing,
The outermost layer of the water droplet collision area at the wing leading edge consists of a non-water-repellent coating film,
The outermost layer of the water-repellent region adjacent to the water droplet collision region is formed of a water-repellent coating film formed by the mixed paint according to any one of claims 1 to 5.

The invention according to claim 7 is the wing according to claim 6,
The non-water-repellent coating film is formed across the water-repellent region from the water droplet collision region,
The water-repellent coating film is formed on the non-water-repellent coating film.

The invention according to claim 8 is an anti-icing system,
The wing according to claim 6 or 7,
Heating means for heating the water droplet collision area;
It is characterized by providing.

The invention described in claim 9 is the ice prevention system according to claim 8,
The heating means can heat at least a part of the water-repellent region on the side of the water droplet collision region.

According to the mixed paint of the present invention, since it is cured at room temperature, it can be suitably used as a paint for large structures such as aircraft. In addition, since the coating film to be formed contains a highly durable room temperature reaction curable resin, it is more durable than a conventional paint (AIS) in which an ultraviolet curable resin and a tetrafluoroethylene resin are mixed. A high water-repellent coating film can be obtained.
Further, according to the wing and anti-icing system of the present invention, the outermost layer of the water droplet collision area at the leading edge of the wing is made of a non-water-repellent coating film, and the outermost layer of the water repellency area adjacent to the water droplet collision area is Since it consists of a water-repellent coating film formed by the mixed paint of the invention, it is possible to efficiently prevent and remove ice.

(A) is sectional drawing for demonstrating an example of the wing | blade and anti-icing system of this embodiment, (b) is the principal part enlarged view. (A) is the SEM photograph of the coating-film surface formed by apply | coating the coating material of Example 2, (b) is the SEM photograph of the coating-film surface formed by apply | coating the coating material (AIS) of Comparative Example 3. It is. (A) is a schematic diagram of the specimen used for the rain erosion test, (b) is a schematic diagram of the rain erosion test apparatus used for the rain erosion test. It is a photograph of a specimen taken before and after the rain erosion test. It is a photograph of a specimen taken before and after the rain erosion test. It is a schematic diagram of an airfoil specimen and a dynamic icing growth apparatus used for an icing wind tunnel test. It is a figure which shows the evaluation result of anti-icing performance. It is a figure which shows the evaluation result of water repellency and water slidability.

  Hereinafter, embodiments of a mixed paint, a wing, and an anti-icing system according to the present invention will be described.

[Mixed paint]
The mixed paint of this embodiment is a room temperature curable paint. Specifically, the mixed paint of the present embodiment is a paint that is obtained by mixing a room temperature reaction curable resin and a particulate fluororesin and is reactively cured at room temperature. The coating film is composed of a room temperature reaction curable resin and a particulate fluororesin. In the present invention, “coating film” refers to a cured coating film.

  Examples of the room temperature reaction curable resin include polyurethane resin, fluororesin, acrylic urethane resin, acrylic resin, and epoxy resin. By using any one or a mixture of these resins, the coating film strength of the mixed paint can be improved, and the coating film on the surface of the object to be coated is hardly peeled even by erosion.

As the particulate fluororesin, for example, tetrafluoroethylene resin (hereinafter referred to as “PTFE”) can be preferably used.
PTFE is prepared, for example, by the manufacturing method of Japanese Patent No. 1937532. The PTFE is not limited to those prepared by the above manufacturing method, and any PTFE may be used as long as it can be mixed well with a room temperature reaction curable resin. In particular, PTFE has a high water-repellent effect and is preferably mixed with a room temperature reaction curable resin. Therefore, those having a low molecular weight, specifically those having an average molecular weight of 500 to 5,000 are preferable.
The particulate fluororesin is not limited to PTFE, and can be arbitrarily changed as appropriate. However, the particulate fluororesin has a high water repellency effect equivalent to or higher than that of PTFE and is well mixed with a room temperature reaction curable resin. What can be done is preferred.

Here, in order to be a highly water-repellent coating film, the water contact angle of the coating film is preferably 100 ° or more, and more preferably 120 ° or more. In addition to high water repellency, the coating film can be expected to have a higher anti-icing effect if it has high water slidability (that is, water is slippery). In order to be a highly lubricious coating film, the water falling angle of the coating film is preferably 10 ° or less. However, if the mixing ratio of the particulate fluororesin to the whole resin component (room temperature reaction curable resin + particulate fluororesin) contained in the paint is small, a highly water-repellent coating film and a highly lubricious coating film can be obtained. become unable. On the other hand, if the mixing ratio of the particulate fluororesin is large, the mixing ratio of the room temperature reaction curable resin with respect to the entire resin component contained in the coating becomes small, so that the durability of the coating film is lowered and the required durability is obtained. I can't do that.
Therefore, the preferable range of the mixing ratio of the particulate fluororesin with respect to the entire resin component contained in the paint can obtain a coating film having a water contact angle of 100 ° or more, and can smoothly perform the coating operation. It is a range in which a coating film having the required durability can be obtained, and a more preferable range is that a coating film having a water contact angle of 120 ° or more can be obtained, and the coating operation can be performed smoothly. The range in which a coating film having the required durability can be obtained, and a more preferable range is a coating film having a water contact angle of 120 ° or more and a water falling angle of 10 ° or less, and a coating operation. Is a range in which a coating film having a required durability can be obtained.

  Similarly, the preferable range of the constituent ratio of the particulate fluororesin in the coating film is a range where the water contact angle of the coating film is 100 ° or more and the coating film can have the required durability. A more preferable range is a range in which the water contact angle of the coating film is 120 ° or more, and the coating film can have a required durability, and a more preferable range is a water contact of the coating film. The angle is 120 ° or more and the water falling angle is 10 ° or less, and the coating film can have a required durability.

  Below, the manufacturing method of the mixed coating material of this embodiment is demonstrated. However, it is not limited to this.

  The room temperature reaction curable resin and the particulate fluororesin are mixed by a general mixing method. Thereby, a liquid mixed paint can be obtained.

  Apply the resulting mixed paint to a single piece of metal such as aluminum, iron, or copper, or a metal of these alloys, ceramics such as tiles, plastics such as PET, etc., paper, cloth, non-woven fabric, coating surface, etc. Can do. Specifically, it is effective to apply to structures such as transport equipment such as aircraft, wind turbine blades, antennas, electric wires, and buildings that require waterproofing and anti-icing.

  The mixed paint of the present invention can be suitably used as a paint for large structures such as aircraft because it is cured at room temperature, that is, it is cured by simply leaving it after application. Conventionally, a coating film formed with a room temperature reaction curable coating is known to have excellent durability because it contains a room temperature reaction curable resin, but is formed with the mixed coating of the present invention. Since the coating film also includes a room temperature reaction curable resin, it is possible to obtain a water-repellent coating film having higher durability than a conventional paint (AIS) in which an ultraviolet curable resin and PTFE are mixed.

[Wings and deicing system]
Fig.1 (a) is sectional drawing for demonstrating an example of the wing | blade 110 and the anti-icing system 100 of this embodiment, FIG.1 (b) is the principal part enlarged view.
The wing 110 of the present embodiment is an aircraft wing, and a non-water-repellent coating film 112 and a water-repellent coating film 113 are formed on the surface of the wing body 111. The wings 110 are not limited to aircraft wings, but may be wind turbine blades, aircraft engine fan blades, wings for generating downforce in vehicles, and the like.
The ice prevention system 100 according to the present embodiment includes the blade 110 according to the present embodiment and a heating element 120 as a heating unit for heating the water droplet collision region P.

Normally, during take-off and landing of an aircraft, the wing 110 is opposed to the relative air flow at a certain angle (elevation angle), and at this time, many of the supercooled water droplets that cause icing are , Collide with a certain area of the wing leading edge. The region where water droplet collision is expected (water droplet collision region P) depends on the flight speed of the aircraft, the angle of the wing relative to the air flow, the size of the water droplet, the wing shape, etc., but these are specified. Thus, the water droplet collision area P can be uniquely determined.
FIGS. 1A and 1B exemplify a mode in which the surface of the portion of 0 to 5% of the chord length from the leading edge of the blade 110 is the water droplet collision region P.

  In the present embodiment, at least a predetermined position inside the blade leading edge corresponding to the water droplet collision area P so that the water droplet collision area P can be heated, the heating element 120 (heating) Means). The heating element 120 is connected to a temperature control device (see FIG. 6) that controls the temperature of the heating element 120.

1 (a) and 1 (b), as the heating element 120, a portion of 0 to 20% of the chord length from the leading edge to the upper surface and a portion of 0 to 15% of the chord length from the leading edge to the lower surface are shown. The embodiment which can be heated is illustrated. That is, in the example illustrated in FIGS. 1A and 1B, the heating element 120 is not only the water droplet collision region P but also the water repellent region Q adjacent to the water droplet collision region P side. These parts are also arranged to be heatable. In this way, by heating at least a part of the water-repellent region Q on the side of the water droplet collision region P by the heating means (heating element 120), more reliable deicing can be performed.
Note that the installation range and the number of the heating elements 120 are not limited to those shown in FIGS. 1A and 1B, and can be arbitrarily changed as long as at least the water droplet collision area P can be heated by the heating elements 120. Is possible.

A water-repellent region Q is formed on the surface of the wing 110 of the present embodiment. The water-repellent region Q is formed by applying a water-repellent paint (mixed paint of this embodiment) obtained by mixing fine powder particles (particulate fluororesin) into a base material (room temperature reaction curable resin). The surface roughness is increased to achieve the water repellency.
1A and 1B exemplify a mode in which the upper and lower surfaces of a portion of 5 to 40% of the chord length from the leading edge are formed as a water-repellent region Q whose outermost layer is a water-repellent coating film 113. ing.

  In this embodiment, as shown in FIG.1 (b), the water-repellent coating film 113 is not formed in the water droplet collision area | region P of a blade front edge part. This is an anti-icing structure adopted based on the knowledge that a surface structure having a large surface roughness exhibits an action of increasing the adhesion strength of icing against dynamic icing. Since the wing 110 of the present embodiment employs the anti-icing structure, the ice core formed at the leading edge of the wing by collision of the supercooled water droplets is melted by the heat from the heating element 120 to become water. After that, when the water-repellent region Q is reached, it is repelled by the water-repellent structure on the surface, and finally detached and removed by the action of air resistance. Here, “dynamic icing” refers to a case where a water droplet collides with an object at a speed like a icing phenomenon on an aircraft wing during take-off and landing and ices.

  In general, water-repellent coatings have lower abrasion resistance and erosion resistance than non-water-repellent coatings, so erosion of water-repellent coatings caused by collisions with moisture, dust, insects, etc. in the atmosphere becomes a problem. . In this regard, in the wing 110 of the present embodiment, the water-repellent coating film 113 is not formed in the water droplet collision region P that is expected to have the highest collision frequency such as dust in the atmosphere. Erosion is avoided, and as a result, maintenance costs can be reduced.

In the wing 110 of the present embodiment, the outermost layer in the water droplet collision area P that does not form the water-repellent coating 113 is a non-water-repellent coating such as a polyurethane paint generally used as a coating material on the surface of an aircraft wing body. The film 112 can be formed. In the case of dynamic icing, the reason why the surface structure having a large surface roughness has the effect of increasing the adhesion strength of icing is that when water droplets collide with the water-repellent coating film at a relative speed of about 40 to 100 m / s. The phenomenon that water droplets enter the concavo-convex structure formed on the surface without being bounced on the surface and freeze, and as a result, the larger the surface roughness, the greater the adhesion strength due to the anchor effect. This is probably because of this. Accordingly, it is preferable that the outermost layer of the water droplet collision region P at the leading edge of the blade is formed by a non-water-repellent coating film 112 such as polyurethane paint, that is, a coating film having a surface roughness smaller than that of the water-repellent coating film 113. It is more preferable to form a coating film having a smaller surface roughness than a conventional coating film such as a paint.
That is, in the wing 110 of the present embodiment, the outermost layer of the water droplet collision region P at the leading edge of the wing is made of the non-water-repellent coating film 112, and the outermost layer of the water repellency region Q adjacent to the water droplet collision region P is It consists of a water-repellent coating film 113 formed by the mixed paint of this embodiment.

Further, with respect to the water repellent region Q of the wing 110 of the present embodiment, it is required to avoid mechanical contact as much as possible in order to maintain the water repellency (surface property). Therefore, from the viewpoint of improving workability related to inspection / maintenance, it is preferable to make the water-repellent region Q as narrow as possible (that is, within a range where necessary anti-icing performance can be obtained).
The outermost layer in the region up to the blade trailing edge adjacent to the water-repellent region Q can be formed by the non-water-repellent coating film 112 or the like.

  The wing 110 of the present embodiment is formed by applying a polyurethane paint or the like to the entire wing main body 111 to form the non-water-repellent coating film 112, and then applying the mixed paint of the present embodiment only to the portion that becomes the water-repellent region Q. Then, it can be produced by forming the water repellent coating film 113. That is, as shown in FIGS. 1A and 1B, in the wing 110 of the present embodiment, the non-water-repellent coating film 112 is formed to extend from the water droplet collision area P to the water-repellent area Q. The aqueous coating film 113 is formed on the non-water-repellent coating film 112.

In order to prevent the non-water-repellent coating film 112 from being formed in the water-repellent region Q, paints are applied separately as in Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-234899). Specifically, polyurethane paint or the like is applied to the water-repellent region. It is also possible to apply only the mixed paint of the present embodiment without applying polyurethane paint or the like to the part to be the water-repellent region Q, and apply to the part other than the part to be Q. However, if the paint is not applied separately as in the present embodiment, the wing body 111 can be more easily applied.
When the paint is applied separately, the wing body 111 is exposed when the water-repellent paint film 113 is eroded. However, if the paint is not applied separately as in this embodiment, the water-repellent paint film should be used. Even if the erosion 113 is eroded, the base of the water-repellent coating 113 (non-water-repellent coating 112) is only exposed, so that the wing body 111 is prevented from being exposed, thereby reducing maintenance costs. be able to.

  In the wing 110 and the anti-icing system 100 of the present invention, the outermost layer of the water droplet collision area P at the leading edge of the wing is composed of a non-water-repellent coating film 112, and the outermost layer of the water repellency area Q adjacent to the water droplet collision area P is The water-repellent coating film 113 is formed by the mixed paint of this embodiment. Therefore, icing can be effectively prevented in an environment where high-speed supercooled water droplets are exposed, so that deicing can be performed efficiently.

  Examples of the present invention will be described below. The present invention is not limited to this.

<Example 1>
The polyurethane resin which is a room temperature reaction curable resin and the particulate fluorine so that the composition ratio of the room temperature reaction curable resin in the coating film is 56.4% by weight and the component ratio of the particulate fluorine resin is 43.6% by weight. Resin PTFE (low molecular weight PTFE) was mixed to obtain the coating material of Example 1. In the paint of Example 1, a particulate fluororesin having an average particle diameter of 1.15 μm was used.

<Example 2>
The coating material of Example 2 was applied in the same manner as the coating material of Example 1 so that the constituent ratio of the polyurethane resin in the coating film was 32.7% by weight and the constituent ratio of the particulate fluororesin was 67.3% by weight. Obtained. In the paint of Example 2, a particulate fluororesin having an average particle diameter of 1.15 μm was used.

<Example 3>
The fluororesin that is a room temperature reaction curable resin and the particulate fluorine so that the composition ratio of the room temperature reaction curable resin in the coating film is 34.2 wt% and the composition ratio of the particulate fluororesin is 65.8 wt%. Resin PTFE (low molecular weight PTFE) was mixed to obtain a paint of Example 3. In the paint of Example 3, a particulate fluororesin having an average particle diameter of 0.96 μm was used.

<Comparative Example 1>
A commercially available polyurethane paint was prepared as the paint of Comparative Example 1.

<Comparative example 2>
The paint of Comparative Example 2 was prepared in the same manner as the paint of Example 1 so that the constituent ratio of the polyurethane resin in the coating film was 74.4% by weight and the constituent ratio of the particulate fluororesin was 25.6% by weight. Obtained.

<Comparative Example 3>
10 g of acrylic resin (UV-75, Origin Electric Co., Ltd.) having a coating film hardness of 5H and 11 g of dry PTFE were mixed. An organic solvent obtained by mixing 24 g of hydrofluorocarbon (Mitsui Dupont Fluorochemical) and 55 g of isopropyl alcohol was added to both the mixed resins. After the addition, these were stirred at room temperature for 5 minutes with a disperser and further stirred for 15 minutes with a motor mill (Eiger Japan) to obtain AIS as a paint of Comparative Example 3.

<Comparative example 4>
As the paint of Comparative Example 4, an existing water-repellent paint was prepared. This water-repellent coating can form a coating film that achieves water repellency without increasing the surface roughness of the coated surface.

[Evaluation of water repellency and water slidability]
The paint of Example 1 is diluted with a solvent such as thinner as necessary, applied to the aluminum alloy surface using an air spray gun (manufactured by Anest Iwata Co., Ltd.), cured at room temperature, and the paint of Example 1 is obtained. A sample prepared by coating was obtained. As application conditions using an air spray gun, the number of times of overcoating was 3 times (film thickness: 30 μm to 50 μm).
In addition, a sample prepared by applying the paint of Example 2 and a sample prepared by applying the paint (polyurethane paint) of Comparative Example 1 in the same manner as the sample prepared by applying the paint of Example 1, And the sample produced by applying the paint of Comparative Example 2 was obtained.
Moreover, about the coating material (AIS) of the comparative example 3, it was hardened by irradiating an ultraviolet-ray. Except for this point, a sample prepared by applying the paint (AIS) of Comparative Example 3 was obtained in the same manner as the sample prepared by applying the paint of Example 1.
Then, for the evaluation of water repellency and water slidability, the water contact angle and the water falling angle of each sample were measured at room temperature using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.).
The results are shown in Tables 1 and 2. In addition, about the sample produced by apply | coating the coating material (polyurethane coating material) of the comparative example 1, the water fall angle was not measured.

From the results shown in Table 1, as the content of the particulate fluororesin (the composition ratio of the particulate fluororesin in the coating film) increases, the water contact angle increases and the content of the particulate fluororesin becomes 43.6% by weight. If it was above, it turned out that a water contact angle becomes 100 degrees or more.
The water contact angle is more preferably 120 ° or more, but from the results shown in Table 1, if the content of the particulate fluororesin is about 50% by weight or more, the water contact angle is estimated to be 120 ° or more. .
More preferably, the water contact angle is 120 ° or more and the water falling angle is 10 ° or less. From the results shown in Table 1, when the content of the particulate fluororesin is about 55% by weight or more, the water contact angle is It is estimated that the water falling angle becomes 10 ° or less at 120 ° or more.

In Table 2, a plurality of samples prepared by applying the paint of Example 2 and a sample prepared by applying the paint (AIS) of Comparative Example 3 are prepared. The result of measuring the water falling angle is shown.
From the results shown in Table 2, it was found that the paint of Example 2 had the same performance as the paint of Comparative Example 3, that is, AIS which is a paint having a high anti-icing effect.
In addition, it was found that the sample produced by applying the paint of Example 2 had smaller variations in water contact angle and water fall angle than the sample produced by applying the paint (AIS) of Comparative Example 3. . This is because the coating film formed by applying the coating material of Example 2 has a fractal surface layer structure than the coating film formed by applying the coating material (AIS) of Comparative Example 3, and PTFE. This is considered to be due to the uniform distribution on the surface.

Here, FIG. 2 (a) shows a SEM photograph of the surface of the coating film formed by applying the paint of Example 2, and FIG. 2 (b) shows the application of the paint (AIS) of Comparative Example 3. The SEM photograph of the surface of the formed coating film is shown.
From these SEM photographs, the coating film formed by applying the paint of Example 2 (see FIG. 2A) was formed by applying the paint (AIS) of Comparative Example 3 (FIG. 2). (See (b)), it can be confirmed that it has a fractal surface layer structure. Moreover, although the granular thing in a SEM photograph is PTFE, the direction of the coating film (refer FIG. 2 (a)) formed by apply | coating the coating material of Example 2 applies the coating material (AIS) of the comparative example 3. FIG. Thus, it can be confirmed that PTFE is uniformly distributed on the surface of the coating film (see FIG. 2B) formed.

[Evaluation of durability]
In order to evaluate the durability of the coating film, a rain erosion test was conducted.
FIG. 3A shows a schematic diagram of the specimen S used in the rain erosion test, and FIG. 3B shows a schematic diagram of the rain erosion test apparatus 10 used in the rain erosion test.
The specimen S has a D shape as shown in FIG. Hereinafter, a portion having a large curvature in the D-shaped curved surface is referred to as a portion S1, and one side of the portion having a small curvature is referred to as a portion S2.

  As shown in FIG. 3B, the rain erosion test apparatus 10 rotates spray nozzles 11 and 11 for spraying a predetermined amount of water particles provided in a cylindrical main body, and a specimen S. And a connecting member 13 for connecting the rotating shaft 12 and the specimen S to each other. At the time of rotation, the specimen S is attached to the connecting member 13 so that the part S1 of the specimen S faces the rotation direction and the part S2 faces the upper side (spray nozzle 11 side). The rain erosion test was performed by rotating S, dropping water droplets from the spray nozzles 11, 11 provided in the upper part of the main body of the rain erosion test apparatus 10, and causing the water droplets to collide with the surface of the specimen S. As test conditions, the precipitation was 25 mm / hour and the specimen speed was 120 mm / second.

The paint of Example 2 was applied to the surface of the aluminum specimen body degreased after the chemical conversion coating treatment using an air spray gun (manufactured by Anest Iwata Co., Ltd.) and cured at room temperature. A specimen S produced by coating was obtained. As application conditions using an air spray gun, the number of times of overcoating was 3 times (film thickness: 30 μm to 50 μm).
In addition, a specimen S produced by applying the paint (polyurethane paint) of Comparative Example 1 was obtained in the same manner as the specimen S produced by applying the paint of Example 2.
Moreover, about the coating material (AIS) of the comparative example 3, it was hardened by irradiating an ultraviolet-ray. Except for this point, the specimen S produced by applying the paint (AIS) of Comparative Example 3 was obtained in the same manner as the specimen S produced by applying the paint of Example 2.
For each specimen S, photographs were taken before and after the rain erosion test. The results are shown in FIG. 4 and FIG.

  As shown in FIG. 4, in the specimen S produced by applying the paint of Example 2 and the specimen S produced by applying the paint (AIS) of Comparative Example 3, a rain erosion test was performed. It turned out that the part which is easy to receive erosion, specifically the coating film of part S1, has peeled. On the other hand, it was found that the specimen S produced by applying the paint (polyurethane paint) of Comparative Example 1 did not peel off the coating film even when the rain erosion test was performed.

  However, as shown in FIG. 5, in the specimen S produced by applying the paint of Example 2, even when the rain erosion test is performed, the portion that is not easily subjected to erosion, specifically, the water repellency of the portion S2 is almost the same. On the other hand, in the specimen S produced by applying the paint (AIS) of Comparative Example 3 when subjected to the rain erosion test, the water repellency of the portion that is not easily subjected to erosion, specifically, the portion S2 is lowered. I understood that. That is, the coating film formed by applying the coating material (AIS) of Comparative Example 3 decreases in water repellency as the erosion progresses and the film thickness decreases, whereas the coating material of Example 2 decreases. The coating film formed by coating was found to have high durability with little deterioration in water repellency even when the erosion progressed and the film thickness decreased. This is considered to be because the durability of the coating film was improved by using a polyurethane resin as a durable room temperature reaction curable resin in the paint of Example 2.

[Evaluation of anti-icing performance]
In order to evaluate the deicing performance of the wing and deicing system, an icing wind tunnel test simulating the flight environment of the aircraft was conducted.
FIG. 6 shows a schematic diagram of the airfoil specimen T and the dynamic icing growth apparatus 200 used in the icing wind tunnel test.

Using the air spray gun, the coating material of Comparative Example 1 was applied to the entire surface of the specimen body made of aluminum and subjected to chemical coating treatment and primer coating so as to have a film thickness of 50 μm, and cured at room temperature. A mold specimen T was obtained. Hereinafter, this is referred to as “sample 1”.
Moreover, the coating material of Example 3 was used for the part 5 to 40% of chord length from the front edge of the sample 1 using an air spray gun (the part in which the water-repellent coating film 113 is formed in FIG.1 (b)). To the same part), and a film thickness of 50 μm was applied and cured at room temperature to obtain an airfoil specimen T. Hereinafter, this is referred to as “sample 2”.
Moreover, the coating material of the comparative example 4 was apply | coated by the method similar to the sample 2, and the wing type specimen T was obtained. Hereinafter, this is referred to as “sample 3”.

First, for each coating film (film thickness: 50 μm) formed with the paint of Example 3 and the paints of Comparative Examples 1 and 4, the surface roughness, water contact angle, and water drop angle were measured at room temperature.
The results are shown in Table 3.

From the results shown in Table 3, it was found that the paint of Example 3 can form a coating film having a water contact angle of 120 ° or more and a water falling angle of 10 ° or less, that is, a highly water-repellent and highly slippery coating film. .
Next, the heating element 120 was attached to each of the samples 1 to 3.

Further, in order to reproduce icing caused by supercooled water droplets in the atmosphere colliding with an object at high speed, a dynamic icing growth apparatus 200 as shown in FIG. 6 was produced. A sample (airfoil specimen T) is set on the downstream side in the air flow path 202 formed in the dynamic ice growth apparatus 200 so that the blade leading edge faces the upstream side, and the temperature in the air flow path 202 is set. The air rectified from the upstream side is blown at a constant wind speed, and the mist is sprayed from the sprayer 204 disposed on the upstream side with a constant LWC and MVD. A test was conducted. As test conditions, the temperature was −15 ° C., the wind speed was 95 m / s, LWC was 0.3 g / m ³ , and MVD was 18 μm. Here, “MVD: Median Volume Diameter” is the diameter at the median value of the volume distribution of the water droplet particles scattered in the dynamic ice growth apparatus 200, and “LWC: Liquid Water Content” is per volume. Is the water content.

The power meter 206 and the temperature control device 208 are connected to the sample, the set temperature of the heating element 120 attached to the sample is changed by the temperature control device 208, and the power consumption of the heating element 120 at that time is changed by the power meter 206. Measured. The set temperatures were 10 ° C, 15 ° C, 20 ° C, 30 ° C, 50 ° C and 60 ° C.
In this example, the heating element 120 heated a portion of 0 to 15% of the chord length. Then, for each set temperature, it was confirmed whether icing had occurred on the surface of the sample 10 minutes after the start of the test.

In sample 1 (that is, a sample having no water-repellent region), the lowest set temperature at which icing did not occur was 60 ° C.
Further, in sample 2 (that is, a sample having a water-repellent region by the paint of Example 3), the lowest set temperature at which icing did not occur was 15 ° C.
Further, in Sample 3 (that is, a sample having a water-repellent region by the paint of Comparative Example 4), the lowest set temperature at which icing did not occur was 50 ° C.

  Here, in a conventional anti-icing system that melts and removes icing by heating the blade leading edge with a heating element, ice nuclei formed on the blade leading edge due to collision of supercooled water droplets It is melted by the heat generated from the heating element provided inside the blade leading edge and becomes liquid phase water. However, this molten water freezes again while flowing in the chord direction along the blade surface due to air resistance, and is fixed to the wing body. Increase the heating temperature to increase the temperature of the non-heated area (blade trailing edge side area) that is not directly heated by heat transfer from the heating area (blade leading edge side area) that is directly heated by the heating element. Although there is a method of evaporating the molten water, there is a problem that the power consumption becomes extremely high. In order to suppress power consumption as much as possible and prevent refreezing, it is necessary to play the molten water with a water-repellent structure while flowing in the chord direction.

Since sample 1 does not have a water-repellent region for repelling molten water while flowing in the chord direction, in order to prevent refreezing, the set temperature of the heating element is raised to 60 ° C. and directly by the heating element. It is necessary to sufficiently raise the temperature of the non-heated area that is not heated.
On the other hand, samples 2 and 3 have a water-repellent region for repelling molten water while flowing in the chord direction. Therefore, the set temperature at which no icing occurs is lower than that at sample 1 and the set temperature at which no icing occurs The lowest was found to be Sample 2. This is because the water-repellent performance of the water-repellent area of sample 2 is high and the molten water can be repelled reliably, preventing re-freezing without increasing the temperature of the non-heated area that is not directly heated by the heating element. This is thought to be possible.

Next, for each sample, an integrated power consumption was calculated by integrating the power consumption (power consumption for 10 minutes) of the heating element 120 at the lowest set temperature at which icing did not occur.
The result is shown in FIG.
As shown in FIG. 7, it was found that the integrated power consumption of sample 1 was the largest, and the integrated power consumption of sample 2 was the smallest. Specifically, when the integrated power consumption of sample 1 was 100%, sample 2 was 30.7% and sample 3 was 58.8%.
As a result, it was found that Sample 2 can cut the integrated power consumption by 70% compared to Sample 1.

<Example 4>
Implemented by mixing polyurethane resin, which is a room temperature reaction curable resin, and PTFE (low molecular weight PTFE), which is a particulate fluororesin, so that the composition ratio of the particulate fluororesin in the coating film is 74% by weight. The paint of Example 4 was obtained. In the coating material of Example 4, a polyurethane resin coating material composed of a main agent (red polyurethane coating material) and a curing agent and having a mixing ratio of main agent: curing agent = 1: 1 was used as the room temperature reaction curable resin. In the paint of Example 4, a particulate fluororesin having an average particle size of 0.96 μm was used.

<Example 5>
The paint of Example 5 was obtained in the same manner as the paint of Example 4 so that the constituent ratio of the particulate fluororesin in the coating film was 77% by weight. In the paint of Example 5, a particulate fluororesin having an average particle size of 0.96 μm was used.

<Example 6>
The paint of Example 6 was obtained in the same manner as the paint of Example 4 so that the constituent ratio of the particulate fluororesin in the coating film was 82% by weight. In the paint of Example 6, a particulate fluororesin having an average particle size of 0.96 μm was used.

[Evaluation of water repellency and water slidability]
The paint of Example 4 is diluted with a solvent such as thinner as necessary, applied to the surface of the aluminum alloy with a spatula, cured at room temperature, and a sample prepared by applying the paint of Example 4 is obtained. It was.
In addition, a sample prepared by applying the paint of Example 5 and a sample prepared by applying the paint of Example 6 were obtained in the same manner as the sample prepared by applying the paint of Example 4.
And about each sample, the water contact angle, the water fall angle, and the surface roughness were measured at room temperature.
The result is shown in FIG. In addition, about the sample produced by apply | coating the coating material of Example 6, the measurement of the water contact angle and the water fall angle was not performed. Further, the surface roughness of the sample prepared by applying the paint of Example 5 was not measured.

From the results shown in FIG. 8, it was found that the paints of Examples 4 to 6 can form a paint film having a water contact angle of 120 ° or more, that is, a highly water-repellent paint film.
Further, from the results shown in FIG. 8, it was found that the surface roughness of the coating film formed with the coating material of Example 6 was larger than that of the coating film formed with the coating material of Example 4. The greater the surface roughness of the coated surface, the higher the water repellency, while the anchor effect increases the adhesion strength of water droplets. Therefore, the larger the surface roughness, the better. It is preferable that the surface roughness is as small as possible within the range of the surface roughness that can have the required water repellency.

From the results shown in Table 1 and FIG. 8, the preferred lower limit of the range of the constituent ratio of the particulate fluororesin in the coating film is 43% by weight, the more preferred lower limit is 50% by weight, and the more preferred lower limit is 55. It was found to be% by weight. Moreover, it turned out that the preferable upper limit of the range of the structural ratio of the particulate fluororesin in a coating film is 82 weight%, and a more preferable upper limit is 77 weight%.
Further, in the coating materials of Example 1 and Example 2, a particulate fluororesin having an average particle diameter of 1.0 μm or more and less than 1.5 μm (specifically, 1.15 μm) was used, and Example 3, Example 4, In the paints of Example 5 and Example 6, a particulate fluororesin having an average particle size of less than 1.0 μm (specifically 0.96 μm) was used. Sufficient dispersibility can be obtained even with a particulate fluororesin having an average particle size of 1.0 μm or more and less than 1.5 μm, but a particulate fluororesin having an average particle size of less than 1.0 μm has better dispersibility, A more uniform (homogeneous) coating film can be formed. The higher the uniformity of the coating film, the more difficult the water-repellent performance will be when the film thickness is thin due to external effects such as erosion. There is an advantage that water repellency equivalent to that immediately after the coating film formation can be reproduced.
In the paints of Examples 4 to 6, a colored paint (specifically, a red polyurethane paint) was used as the main component of the room temperature reaction curable resin paint. This makes it possible to visually check the film formability of the coating film, the deterioration of the coating film (such as the degree of peeling), and the like.

100 ice prevention system 110 wing 112 non-water-repellent coating 113 water-repellent coating 120 heating element (heating means)
P Water droplet collision area Q Non-water-repellent area

Claims (9)

A mixture of a room temperature reaction curable resin that cures at room temperature and a particulate fluororesin,
A mixed paint, wherein the composition ratio of the particulate fluororesin in the coating film is 43 wt% or more and 82 wt% or less.   The mixed paint according to claim 1, wherein the particulate fluororesin is a tetrafluoroethylene resin.   The mixed paint according to claim 1, wherein the room temperature reaction curable resin is a fluororesin.   The mixed paint according to any one of claims 1 to 3, wherein an average particle size of the particulate fluororesin is less than 1.5 µm.   The mixed paint according to claim 4, wherein an average particle diameter of the particulate fluororesin is less than 1.0 μm. The outermost layer of the water droplet collision area at the wing leading edge consists of a non-water-repellent coating film,
6. The wing according to claim 1, wherein the outermost layer of the water-repellent region adjacent to the water droplet collision region is formed of a water-repellent coating film formed by the mixed paint according to claim 1. The non-water-repellent coating film is formed across the water-repellent region from the water droplet collision region,
The wing according to claim 6, wherein the water-repellent coating film is formed on the non-water-repellent coating film. The wing according to claim 6 or 7,
Heating means for heating the water droplet collision area;
An anti-icing system characterized by comprising:   9. The ice prevention system according to claim 8, wherein the heating means can also heat at least a part of the water-repellent region on the side of the water droplet collision region.