JPH0826176A - Forming method of surface reducing underwater frictional resistance - Google Patents

Abstract

PURPOSE:To provide the forming method of an underwater frictional resistance reduced surface that is large in a contact angle, longer in a span of holding time for an air film and excellent in quality. CONSTITUTION:A specified pulverulent body is mixed in resin, and an obtainable mixture is applied on a base surface. This pulverulent body is mixed in the resin and made into a mixture, and in this constitution, its mixed rate to the pulverulent body is made so as to make volume ratio R become more than 40% and less than 90% in an equation [volume ratio R = (powder volume)/(powder volume + resin solid volume) X 100], and then this mixture is made so as to be applied on the base surface. Accordingly, since some unevenness due to the pulverulent body is formed on a film surface made up on the base surface, a contact angle becomes more than 110 deg.C. In consequence, air film holding performance of this film surface is securable without fail.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a surface for reducing frictional resistance in water, and more particularly to a method for forming a surface for reducing frictional resistance in water in a structure having a surface in contact with water such as a ship or a liquid transport pipe.

[0002]

2. Description of the Related Art Generally, in a structure having a submerged surface such as a ship or a liquid transport pipe, that is, a surface in contact with water, a flow of water occurs along the surface, and at this time, a fluid frictional resistance due to a shear resistance occurs. . By the way, as a method for reducing this fluid frictional resistance in a ship, a method of forming a frame-shaped air chamber by providing a protrusion on the ship bottom and supplying air into this air chamber to form an air layer on the ship bottom surface, Alternatively, a so-called micro-bubble method has been proposed in which air is ejected onto the surface of a hull to generate a large number of bubbles on the surface of the hull.

However, in the former case, there is a problem that when the ship sails, the air held in the air chamber flows out, and a large amount of power is required to replenish the air, and in the latter case, it is installed on the side of the ship or on the bottom of the ship. Since frictional resistance does not decrease unless a large amount of air is supplied from the nozzle, a large compressor must be installed, and a large amount of power is required to drive it as the equipment cost increases.

That is, the supplied air becomes bubbles to flow along the side of the ship or the bottom of the ship to reduce the fluid friction resistance. There is a problem that the area of the bubbles covering the area is reduced and the effect of reducing the fluid frictional resistance is reduced. Therefore, none of them could be put to practical use.

Therefore, the applicant of the present invention has found that the submerged surface of a structure having a submerged portion has fine irregularities on its surface, and at least the tops of the irregularities are formed of a water repellent material. To reduce the fluid frictional resistance by supplying air to this surface to form an air film between the surface of the film and water, and the film is a coating or a sheet or film made of a synthetic resin. And its surface is the interval between convex parts
0.3 to 30 μm and the ratio h / S between height h and spacing S is 0.
It was previously proposed that the structure be composed of 3 to 3 fine irregularities (Japanese Patent Application No. 5-241792).

[0006]

By the way, when the surface having fine irregularities as described above is prepared by mixing powder having water repellency and a resin for fixing the powder and coating the mixture,
Make sure that the powder projects onto the surface of the paint (resin) layer.
There was a problem that it was necessary to clarify the powder ratio to be charged.

The present invention has been made in order to solve the above-mentioned conventional problems, and is an underwater friction in which a paint (mixture) having a specific powder ratio is applied to the surface of a substrate. A method for forming a surface with reduced resistance is provided.

[0008]

In the method for forming a surface for reducing frictional resistance in water according to the present invention, a powder is mixed with a resin to form a mixture, and the mixture has a powder mixing ratio of powder volume ratio R =
(Powder volume) / (powder volume + resin solid content volume) x 100
It is characterized in that it is 40% or more and less than 90% and that the mixture is applied to the surface of the substrate.

[0009]

The contact angle is 110 ° C. or more because the asperities formed by the powder are formed on the surface of the coating film formed on the surface of the substrate by the method of forming a surface for reducing frictional resistance in water. As a result, the function of reliably retaining the air film on the surface of the coating film is obtained. Hereinafter, the configuration of the present invention will be described in detail.

The surface of the ship is painted. Therefore, the inventors have invented a method for producing a surface for reducing frictional resistance in water using a coating facility. The underwater frictional resistance reducing surface is prepared by mixing powder and resin and coating this, and the surface of the coating film has a fine uneven structure formed by the powder or the powder and the resin. . The powder may be any of those having a low surface energy such as polytetrafluoroethylene (PTFE), hydrophobic silica, and hydrophobic alumina, and a water-repellent material having a contact angle θ with water of 90 ° or more. This powder has an average particle size of 0.1 μ
The size is preferably about m to 30 μm. Since the resin is used for fixing the particles, it is not necessarily required to be water repellent, and for example, polyester resin, phenyl resin, amino resin, epoxy resin, urethane resin, or any other suitable coating material Either may be used.

These powders, a coating resin, and additives such as a curing agent, a plasticizer and a diluent are added, stirred and mixed, and the resulting mixture is applied to the surface of a substrate for coating. The coating method may be any ordinary coating method using a brush, a spatula, a roller, an air spray gun, an airless spray gun, or the like. The coating surface thus prepared has a contact angle θ with water of at least θ ≧ 90 ° and forms an air film. The injected air flows along the painted surface.

The surface structure at this time is such that the convex-concave convex-concave interval s is 0.3 to 30 μm, and the height h of the convex part is equal to the interval s.
It is desirable that / s is in the range of 0.3 to 3. Further, the ratio of the volume of powder in this coating film: volume ratio R = (powder volume)
It is desirable that / (powder volume + resin solid content volume) × 100 is 40% or more and less than 90%, preferably 50% or more and less than 80% as shown in FIG. In the present invention, the volume ratio R is 40
% And less than 90%. This is because the volume ratio R is 40%
If it is less than 100%, the air film formation on the coating film will be incomplete, and if it is 90% or more, defects such as cracks will easily occur on the coating film. Further, the reason why the content is preferably 50% or more and less than 80% is that, within this range, there are no defects such as cracks on the coating film and a stable air film forming surface is obtained.

As can be seen from FIG. 1, the powder volume ratio R is
When it is 40% or more, the substrate surface becomes a complete air film forming surface, and the contact angle of the surface at this time is θ ≧ 110 ° or more.
In the case of powder having pores, the volume obtained by combining the true volume and the pore volume is defined as the powder volume. After coating, the powder projects onto the surface of the coating film.

[0014]

【Example】

Example 1 A Neugarmet clear top coat (Tope), which is a fluororesin-based paint, is mixed with a curing agent, and the average particle diameter is 3.5 μm so that the paint: powder has a weight ratio of 7: 3. Silica: Silohobic 704 (Fuji Silysia) mixed,
Dispersed. Neugarmet thinner was added to the mixture in the same weight as silica to dilute it, and the viscosity was adjusted.

Epoxy-based anticorrosive paint: An aluminum plate previously coated with Newgarmet undercoat (Tope) was spray-coated with an air gun, and dried at room temperature for 5 hours or more to obtain a coated surface. It was observed that the contact angle of water on this surface was θ = 168 °, an air film was formed when immersed in water, and that when air was injected, it flowed upward along the coated surface. The surface unevenness is
The interval s between the protrusions was 5.2 μm, the 10-point average roughness representing the height h was 2.8 μm, and h / s = 0.53.

Volume ratio of powder contained in this coating film R = 78
%Met. Example 2 A fluororesin-based coating, Neugarmet Clear Topcoat (Tope), was mixed with a curing agent, and the coating: powder was in a weight ratio of 1: 1 and had an average particle diameter of 7 μm. (Daikin Industries) mix and disperse to about 5
Newgarmet thinner was added by a weight of 50% to dilute the mixture to adjust the viscosity.

Epoxy-based anticorrosive paint: An aluminum plate previously coated with Newgarmet undercoat (Tope) was spray-coated with an air gun, and dried at room temperature for 5 hours or more to obtain a coated surface. With the contact angle of water on this surface θ = 160 °,
It was confirmed that an air film was formed when immersed in water. When air was injected into this air film, it was observed that it flowed upward along the coated surface.

When the surface roughness was measured with a surface roughness meter, the average spacing s between the projections of the projections and depressions was 12.6 μm, and the height h was
The 10-point average roughness representing R was 5.2 and h / s = 0.41. The volume ratio R of the powder contained in this coating film was 57%. Comparative Example 1 In order to compare with Example 1 and Example 2, a fluororesin paint was spray-coated on an aluminum plate with an air gun to obtain a smooth coated surface. The contact angle with water was θ = 72 °, and no air film was formed even when immersed in water. Also, even if air is sent onto the painted surface, the air does not flow on the painted surface,
Surfaced as bubbles. Comparative Example 2 Fluorine resin paint, Neugarmet clear topcoat (Tope) was mixed with a curing agent, and the paint: powder weight ratio was 94: 6.
Hydrophobic silica with an average particle size of 3.5 μm such that:
Mixed with Silohobic 704 (Fuji Silysia). Newgarmet thinner was added in the same amount as silica for dilution to adjust the viscosity.

Epoxy-based anticorrosive paint: A Newgarmet undercoat (Tope) was applied to an aluminum plate by spraying with an air gun, and dried at room temperature for 5 hours or more to obtain a coated surface. When the contact angle of water on this coated surface was θ = 106 °, an air film was only partially formed even when immersed in water. The volume ratio R of the powder was 39%. Comparative Example 3 A fluororesin paint, Neugermett clear topcoat (Tope) was mixed with a curing agent, and the weight ratio of paint: powder was 70:30.
The fluororesin powder Lubron L5 having an average particle size of 7 μm was mixed and dispersed so that the ratio became, and Neugermet thinner was added to dilute the powder by about 50% of the powder to adjust the viscosity.

An aluminum plate previously coated with an epoxy anticorrosive paint was sprayed with an air gun for coating, and dried at room temperature for 5 hours or more to obtain a coated surface. The contact angle of water on this coated surface was θ = 86 °, and no air film was formed even when immersed in water. The volume ratio of the powder was R = 36%. Comparative Example 4 Fluorine resin coating, Neugarmet clear topcoat (Tope) was mixed with a curing agent, and the coating material: powder was 45:55 by weight.
And a hydrophobic silica having an average particle size of 3.5 μm; Silophobic 704 (Fuji Silysia). Add the same amount of New Garmet thinner and silica to dilute,
The viscosity was adjusted.

An epoxy-based rust preventive paint; a Newgarmet undercoat (Tope) was applied to an aluminum plate by spraying with an air gun, followed by drying at room temperature for 5 hours or longer to obtain a coated surface. An air film was formed when the coated surface was immersed in water at a contact angle θ of water of 165 °. It was confirmed that when air was injected into this air film, it flowed upward along the coated surface. It was confirmed that when air was injected, it flowed upward along the coated surface.

However, cracks were confirmed on the coated surface, the surface was easily peeled off and was brittle, and the durability as the coated surface was also evaluated by the cross cut test and 0 by the cellophane tape peeling test. The powder content of this coated surface was 91.7%.

[0023]

As described above, according to the present invention, since the resin coating material mixed with the powder is applied to the surface of the substrate and the volume ratio R of the powder is determined, the air film is surely formed. Therefore, it is possible to form a favorable surface for reducing frictional resistance in water. Further, according to the present invention, the conventional shipbuilding process can be introduced without difficulty when producing the underwater frictional resistance-reducing surface, so that the conventional equipment can be used as it is and the underwater frictional resistance-reducing surface can be applied to the ship by painting. It has effects such as simplification of implementation, reduction of capital investment, reduction of fluid friction resistance due to air film formation and air inflow, which can be applied to actual ships. Furthermore, by mixing the powder with the resin, the powder volume ratio exposed on the surface of the coating film can be adjusted.
By adjusting the amount to be less than 90%, it is possible to intentionally produce an uneven structure suitable for forming an air film. In addition, the coated surface obtained by mixing the powder with the resin and applying the resin can control the surface irregularity formation by adjusting the powder blending amount. In particular, when the volume ratio of the powder is 40% or more, the surface is covered with the powder exposed on the surface, and the uneven structure formed has a space between the convex portions and the convex portion s.
And the ratio h / s to the height is a value suitable for forming an air film.

[Brief description of drawings]

FIG. 1 is a relationship diagram between a volume ratio of powder in a coating film and a contact angle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Nakatani No. 1 Yawata Kaigan Dori, Ichihara City, Chiba Mitsui Engineering & Shipbuilding Co., Ltd. Chiba Works

Claims (2)

[Claims] 1. Powder is mixed with resin to form a mixture, and the mixture has a powder mixing ratio of powder volume ratio R = (powder volume) / (powder volume + resin solid content volume) × 100 is 40% or more 9
A method of forming a surface for reducing frictional resistance in water, characterized in that the content is adjusted to be less than 0% and the mixture is applied to the surface of a substrate. 2. The method for forming a surface for reducing frictional resistance in water according to claim 1, wherein the powder is made of a water-repellent material, and the powder is projected on the surface of the coating film.