JP2001302984A - Covering material for bottom of ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a covering material for the bottom of a ship which realizes a low flowing water resistance by ultra-water repellency and can maintain the ultra-water repellency for a long period of time. SOLUTION: The porous material having been provided with water repellency treatment is used as the covering material of the bottom of a ship.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottom coating material for coating a hull, in particular, a bottom of the hull, thereby reducing the water resistance of the marine vessel.

[0002]

2. Description of the Related Art Conventionally, various paints have been developed in order to reduce the running water resistance of a hull. For example, a hydrophilic ship bottom coating material in which a water swelling material is blended with a rubber raw material is disclosed in
No. 324481. Japanese Patent Application Laid-Open No. 5-1172741 discloses a hydrophilic ship bottom paint using an inorganic colloid sol, a hydrophobic thermoplastic resin fine particle, and a water dispersant containing a crosslinking agent, and a construction method using the same.

However, since the conventional bottom material is made of a material which is smooth and has high hydrophilicity with respect to water, there is a limit in reducing the resistance to flowing water, and a low flowing water as obtained from super water repellency is limited. The resistance value could not be realized.

In order to obtain a super-water-repellent surface, for example, there is a method in which a water-repellent coating using a fluororesin such as polytetrafluoroethylene (PTFE) or a perfluoroalkylsilane coupling agent is applied to the ship bottom. Since it is covered with fluorine atoms, it exhibits super-water repellency against water or seawater, realizes an interface floating on water or seawater, and can significantly reduce the resistance of flowing water. However, a water-repellent coating using a fluorine-based resin such as PTFE or a perfluoroalkylsilane coupling agent,
Since it was a very thin layer of less than 0.01 mm, it was susceptible to abrasion and could not maintain super water repellency for a long time in a state of being exposed to rough waves. In the conventional technology,
It was not possible to impart super water repellency to the inside of the coating material by thickening the super water repellent film.

[0005]

As described above, since the conventional ship bottom material is made of a material which is smooth and has enhanced hydrophilicity, there is a limit in reducing the flowing water resistance.
It was not possible to realize a low flowing water resistance value obtained from super water repellency. In addition, when a water-repellent coating using a fluorine resin such as PTFE or a perfluoroalkylsilane coupling agent is applied to the bottom of the ship,
Super water repellency could not be maintained for a long time.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention provides a super-water-repellent surface having excellent abrasion resistance so that a low water flow resistance obtained from the super-water repellency can be obtained. The realization of value.

That is, the first invention relates to a ship bottom covering material made of a porous material subjected to a water-repellent treatment (claim 1).

In a second aspect, the water-repellent porous material has a thickness of 0.1 to 10 mm, a porosity of 40 to 98%, and an average pore diameter of 0.001 to 0.05 mm. (Claim 2).

In a third aspect of the present invention, the water-repellent porous material is made of carbon powder, ceramic powder, metal powder,
The present invention relates to a ship bottom covering material which is a porous material obtained by mixing a resin or rubber with at least one selected from the group consisting of carbon fiber, ceramic fiber and metal fiber, and then performing a water-repellent treatment.

A fourth invention relates to a ship bottom covering material, wherein the porous material subjected to the water repellent treatment is a porous material obtained by subjecting a foamed metal to a water repellent treatment (claim 4).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A ship bottom covering material according to the present invention is made of a water-repellent porous material. By using the porous material subjected to the water-repellent treatment, a low flowing water resistance value can be maintained for a long time.

The thickness of the bottom coating material is preferably from 0.1 to 10 mm, more preferably from 0.2 to 5 mm. When the thickness is less than 0.1 mm, the strength as a porous body cannot be maintained, and the strength as a ship bottom covering material cannot be obtained. On the other hand, when the thickness is more than 10 mm, the weight tends to be heavy and the cost tends to be high.

[0013] The porosity of the ship bottom coating material is preferably 40 to 98%, more preferably 50 to 80%. If it is less than 40%, the hydrophilicity of the base material becomes greater, and it becomes difficult to maintain the super water repellency.
If it is larger than 8%, the strength of the base material tends to be weak.

The average pore diameter of the ship bottom coating material is 0.001.
To 0.05 mm, preferably 0.01 to 0.1 mm.
More preferably, it is 03 mm. The average pore size is 0.
If it exceeds 05 mm, there is a tendency that sufficient super water repellency cannot be maintained. This is considered to be due to the fact that the repulsion force was weakened due to the increase in the pore diameter. On the other hand, when the average pore diameter is less than 0.001 mm, it is difficult to impregnate the pores with a water-repellent material, and the water-repellent treatment tends to be difficult.

The water-repellent treatment of the porous material means a treatment for forming a layer having fluorine or silicone on the surface.

The porous material refers to a material having a myriad of unobstructed pores inside.

As the porous material, a resin or rubber is mixed with at least one selected from the group consisting of carbon powder, ceramic powder, metal powder, carbon fiber, ceramic fiber and metal fiber, and then water-repellent. The material is preferable because it has strength and corrosion resistance and has coating properties.

Of these, carbon powder is particularly preferred because it is excellent in corrosion resistance, light and inexpensive.

Examples of the resin include a phenol resin, an acrylic resin, a fluorine resin, and a silicone resin. Examples of the rubber include neoprene (registered trademark) rubber, a fluorine rubber, and a silicone rubber. .

As the porous material, a porous material obtained by subjecting a foamed metal to a water-repellent treatment can be manufactured at a low cost, and the shape of the coating material is fixed in a bent shape in accordance with the shape of the ship bottom by press working or the like. It is preferable because it is easy.

The foam metal refers to a metal in which a large number of pores are formed in a molten state, such as foamed stainless steel, foamed aluminum and foamed nickel.

The water-repellent treatment of the foamed metal means that the metal is impregnated with a perfluorosilane coupling agent, a fluorine-based resin, a silicone-based resin or the like, and is subjected to a heat treatment to exhibit water-repellency.

As a preferred specific example of the water-repellent treatment of the foamed metal, as shown in FIG. 3, for example, a foamed stainless steel sheet is provided on an in-cylinder injection type internal combustion engine as described in JP-A-10-159688. It can be obtained by performing water repellent treatment on foamed stainless steel using a water repellent treatment method using a silane coupling agent such as that used for the inner wall of the fuel injection valve. For example, a metal alkoxide and an alkoxyl group can be obtained. It can be obtained by applying a coating solution containing a fluoroalkyl group-substituted alkoxide partly substituted with a fluoroalkyl group, followed by firing. According to this water-repellent treatment, a super-water-repellent surface such as soft fur having a metal surface covered with a fluorine group can be obtained.

Based on the embodiment shown in FIG. 1, the same reference numerals are given to the same or corresponding parts as in the prior art, and the configuration of the present invention and its operation will be described. FIG. 1 is an enlarged schematic cross-sectional view of a ship bottom covering material according to a third invention. In the drawing, reference numeral 2 denotes a water bottom repellent ship bottom covering material made of a porous material, 3 denotes a porous material, Reference numeral 4 schematically shows pores.

The function of the water repellency inside the pores will be described with reference to the drawings. FIG. 2 is a diagram showing the relationship between the pore diameter of the porous body, the contact angle, and the repulsive or attractive force. FIG.
In, the pore diameter is not represented by the diameter but by the pore radius ra. ΔP is the repulsive force or suction force, if positive, the suction force,
If it is negative, it will be a repulsive force. The following equation is ΔP and the pore radius ra,
This shows the relationship of the contact angle θ. ΔP = 2γ cos θ / ra (1)

Whether ΔP becomes a repulsive force or a suction force is determined by
Is determined depending on whether the contact angle θ is greater than or less than 90 degrees. In addition, the smaller the pore radius ra, the more Δ
The absolute value of P increases. Therefore, the stronger the water repellency of the pores and the smaller the pore diameter, the more powerful super water repellency is realized. It is clear from FIG. 2 and Equation 1 that the super water repellency inside the pores is stronger than the super water repellency on the smooth surface.

Further, in the case of a porous body, even if the surface layer is scraped by abrasion, a new super water repellent pore surface 4 always appears, so that the super water repellency is maintained.

The third ship bottom covering material according to the present invention comprises:
For example, a carbon cloth impregnated with a paste obtained by adding carbon powder and PTFE dispersion,
It can be obtained by heating at 00 ° C. for about 15 minutes to melt and bind PTFE.

[0029]

EXAMPLES Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 As the porous material 3, furnace black (Vulcan XC72, Cabot Corporation, USA) and PTFE dispersion (Polyflon D-1, Daikin Industries, Ltd.), which are a kind of carbon powder, were put on a 0.3 mm thick carbon cloth. Was added, and the paste was impregnated and heat-treated at 400 ° C. for 15 minutes to melt and bind PTFE.

The pore distribution and the porosity of a part of the water-repellent carbon cloth thus produced were examined by a mercury intrusion porosimeter, and the average pore diameter was 0.00.
5 mm, and the porosity was 60%. The thickness of the porous material after the water-repellent treatment was measured with a micrometer and found to be 0.31 mm. This carbon cloth clearly showed super water repellency, and when water and seawater were dropped on the carbon cloth, it became spherical and spilled. Therefore, the super water repellent of Example 1 is very strong.

This super-water-repellent carbon cloth was stuck on the bottom of a large model ship (at a position below the waterline), and the difference in speed from that when a conventional hydrophilic paint was applied was examined. Using a large circular water tank, fresh water was poured, and a large model ship equipped with a propeller driven by a DC motor was floated, and the number of laps of the large model ship within a certain time was examined. As a result, compared to the case where the conventional hydrophilic paint is applied, 45
%, And it was confirmed that the super-water-repellent material was able to significantly reduce the water resistance of the hull.

Further, the bottom-coating material according to the first embodiment is put into an automatic washing machine having a dehydrating function, and salt is added instead of the washing soap. When the same test was carried out after repeating the number of times, the flowing resistance value of the hull hardly changed.

In place of the carbon powder, ceramic powder, metal powder, carbon fiber, ceramic fiber or metal fiber may be used, and a similar effect can be obtained by using a mixture thereof.

Example 2 A 0.5 mm thick foamed stainless steel sheet was used as a porous material, and was applied to the inner wall of a fuel injection valve of a direct injection internal combustion engine as described in JP-A-10-159688. The water-repellent treatment was performed on the foamed stainless steel using a water-repellent treatment method using a silane coupling agent as used. According to this water-repellent treatment, a super-water-repellent surface such as soft fur having a metal surface covered with a fluorine group can be obtained. Specifically, 3 g of tetraethoxysilane, 1 g of heptadecafluorodecyltrimethoxysilane, 40 g of ethanol, and 0.1 g of ethanol were added.
3 g of a 05N hydrochloric acid aqueous solution was mixed and stirred. Next,
The obtained solution was applied to a foamed stainless sheet, dried, and then heat-treated at 250 ° C. for 1 hour.

Using a part of the water-repellent foamed stainless steel sheet prepared as described above, the pore distribution and porosity were examined by a mercury intrusion porosimeter. The average pore diameter was 0.01 mm and the porosity was 80%. %Met. Also,
The thickness of the porous material after the water-repellent treatment was measured with a micrometer and found to be 0.51 mm. The water-repellent foamed stainless steel sheet clearly exhibited super-water repellency. When water and seawater were dropped on the water-repellent foamed stainless steel sheet, the sheet became spherical and spilled.

The super-water-repellent foamed stainless steel sheet was attached to the bottom of a large model ship (at a position below the waterline), and the difference in speed from the case where a conventional hydrophilic paint was applied was examined. Using a large circular water tank, fresh water was poured, and a large model ship equipped with a propeller driven by a DC motor was floated, and the number of laps of the large model ship within a certain time was examined. As a result, the number of times was increased by about 35% compared to the case where the conventional hydrophilic paint was applied, and it was confirmed that the super-water-repellent material was able to significantly reduce the flowing resistance value of the hull. Was.

As in the case of the first embodiment, the bottom coating material is put into an automatic washing machine having a dehydrating function, and salt is added instead of the washing soap, and washing, dehydrating, rinsing, dehydrating, rinsing, and dehydrating washing are performed. After repeating the stroke cycle for 40 times, a similar test was conducted, and the flowing resistance of the hull hardly changed.

In place of the foamed stainless steel, other foamed metals such as foamed aluminum and foamed nickel may be used, and the same effect can be obtained.

In Examples 1 and 2, using various materials such as carbon powder, ceramic powder, metal powder, carbon fiber, ceramic fiber, and metal fiber, the thickness, porosity, and average porosity of the porous material were used. The pore size was examined. As a result, first, when the thickness was less than 0.1 mm, the strength as a porous body could not be maintained, and the strength as a ship bottom covering material could not be obtained. But,
No reduction in water repellency was observed even when the thickness exceeded 5 mm for the thick portion. If the porosity is less than 40%, the hydrophilicity of the base material becomes greater, and it becomes difficult to maintain the super water repellency. However, even if the porosity exceeds 80%, there is no problem in the strength as a ship bottom covering material as long as the strength of the base material such as metal is maintained. On the other hand, regarding the pore diameter,
Regardless of the base material, if the average pore diameter was 0.05 mm or less, super water repellency could be maintained even when worn. However, when it exceeded 0.05 mm, sufficient super water repellency could not be maintained.

[0041]

According to the first ship bottom covering material of the present invention, a low water resistance can be maintained for a long time by using a water-repellent porous material.

According to the second ship bottom covering material of the present invention, it has a thickness of 0.1 to 10 mm, a porosity of 40 to 98%, and an average pore diameter of 0.001 to 0.05 mm, The hull bottom coating material is made of water-repellent porous material, so even when worn, new super-water-repellent pores always appear, exhibiting super-water-repellency that can be maintained for a long time, and the water resistance of the hull Is significantly reduced.

According to the third ship bottom covering material of the present invention, the porous material is selected from the group consisting of carbon powder, ceramic powder, metal powder, carbon fiber, ceramic fiber and metal fiber. After mixing the resin or rubber, the water repellent treatment is applied, so that super water repellency that can be maintained for a long period of time is expressed, and there is an effect that the flowing water resistance value of the hull can be significantly reduced, and the bottom of the ship is covered. And can be removed if necessary.

According to the fourth ship bottom covering material of the present invention, since the porous material is formed by applying a water-repellent treatment to the foamed metal, it is formed according to the shape of the ship bottom, and is fitted into the ship bottom. Can be removed according to. Further, since the inner wall of the pore portion is kept super water repellent, even if the surface is roughened or worn, new super water repellent surfaces appear one after another, and the super water repellency can be maintained for a long period of time.

[Brief description of the drawings]

FIG. 1 is an enlarged schematic cross-sectional view of a ship bottom covering material according to a first embodiment.

FIG. 2 is a diagram illustrating a relationship between a pore diameter, a contact angle, and a repulsive force or a suction force according to the first embodiment.

FIG. 3 is an enlarged schematic cross-sectional view of a ship bottom covering material according to a second embodiment.

FIG. 4 is an enlarged schematic sectional view of a conventional ship bottom covering material.

[Explanation of symbols]

1 Steel plate at the bottom of ship, 2 Bottom covering material composed of porous material and subjected to water-repellent treatment, 3 Porous material, 4 pores, 5
Hydrophilic bottom coating material, 6 coating material inside, 7 coating material surface, 8 foam metal.

Claims (4)

[Claims] 1. A ship bottom covering material comprising a porous material subjected to a water repellent treatment. 2. The porous material having been subjected to the water-repellent treatment has a particle size of 0.1.
With a thickness of 1-10 mm, a porosity of 40-98% and 0.0
The ship bottom covering material according to claim 1, which has an average pore diameter of 01 to 0.05 mm. 3. After the water-repellent porous material is mixed with a resin or rubber, at least one selected from the group consisting of carbon powder, ceramic powder, metal powder, carbon fiber, ceramic fiber and metal fiber. 3. The ship bottom covering material according to claim 1, which is a porous material subjected to a water-repellent treatment. 4. The ship bottom covering material according to claim 1, wherein the water-repellent porous material is a porous material obtained by performing a water-repellent treatment on a foamed metal.