JPS60250076A - Antifouling ship bottom paint which can reduce frictional resistance in water - Google Patents

Abstract

PURPOSE:To provide a consumable antifouling ship bottom paint which contains limited amounts of an antifouling agent and a pigment, gives excellent protection against contaminating organisms and reduces frictional resistance to sea water. CONSTITUTION:The antifouling paint is prepd. by adding a plasticizer, a solvent, an antifouling agent (e.g. copper suboxide) and a pigment (e.g. red oxide or clay) to a vehicle consisting of an acrylic polymer which contains about 65wt% or higher triorganotin salt of an alpha,beta-unsatd. mono- (or di-) basic acid (e.g. tributyltin methacrylate). The antifouling agent and pigment are added in such amts. that they may be contained in coating film in 20vol% or lower in total.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a ship bottom antifouling paint that reduces underwater frictional resistance, and more specifically, it can be applied to submerged parts of ships and marine structures to protect them from fouling organisms, and also to protect them from seawater in the corresponding parts. This invention relates to an antifouling paint for the bottom of a ship that can reduce frictional resistance.

If fouling organisms adhere to the bottom of the hull, or if the surface of the hull becomes rough for some reason, resistance increases, leading to wasted propulsion energy and hindering ship operation.

The frictional resistance of a ship with seawater is affected by the surface condition (surface roughness) of the ship's hull, and the main factor that increases this frictional resistance is due to biological deposits on the hull's outer plating. , corrosion of the ship's steel plates, or an increase in roughness due to the skeleton structure based on an insoluble matrix depending on the ship's bottom paint.

In order to minimize the effects of increasing roughness, various antifouling paints have conventionally been applied to ship hulls to prevent biological deposits. Typical antifouling agents used in ship bottom antifouling paints include cuprous oxide, cuprous Rodan, and organic tin compounds, as well as film-forming resins and elution aids for antifouling agents. be done.

Furthermore, in recent years, antifouling paints for ship bottoms have been proposed, the main component of which is an antifouling component chemically bonded to a film-forming resin.

According to this paint, the formed coating film gradually undergoes a hydrolysis reaction in seawater, and the antifouling agent is released into the seawater to exert an antifouling effect, and at the same time, the film-forming resin after hydrolysis also becomes water-soluble. The paint film itself gradually dissolves in seawater. It wears out more quickly than other paints, and its surface becomes smoother over time.An example of the hydrolysis mechanism of such a paint film is as follows.

Bu (Coating film mainly composed of a copolymer of tributyltin methacrylate and methyl methacrylate) Ha (Water-soluble acrylic copolymer film) Bu (Antifouling agent) To prevent ship hull corrosion,
The problem is being solved by applying paints such as cool epoxy, chlorinated rubber resin, and vinyl chloride resin.

In addition, the increase in roughness caused by the formation of a skeleton structure caused by certain ship bottom paints can be solved by the above-mentioned paint film consumption type. In other words, the surface of the bottom coating becomes smooth as the ship sails, and as a result, the area of contact with seawater is reduced, reducing frictional resistance and improving navigation performance.

The inventors of the present invention have carried out intensive research to provide an antifouling paint for ship bottoms that has excellent antifouling performance and at the same time actively reduces frictional resistance with seawater. It has been found that by reducing the amount of pigment bones blended to a certain amount or less, there is a significant effect of reducing frictional resistance and an extremely excellent effect of improving slime resistance. The remarkable reduction in frictional resistance and the excellent improvement in slime resistance are
This is thought to be due to the following reasons. cuprous oxide,
The above-mentioned film-consumable antifouling paint containing copper rodanide, other antifouling agents, coloring pigments, extender pigments, etc., shows that from a macroscopic perspective, the convex parts wear out faster than the concave parts, and the friction resistance increases. However, microscopically, the surface of the paint film shows irregularities due to the eluted antifouling agent and uneluted pigment bones, and the microscopic surface roughness C is lower than the initial value. On the contrary, it is increasing. On the contrary, this compounded antifouling agent,
By reducing the content of pigment bones to a certain level or less, in addition to reducing the macro-level unevenness that is characteristic of the above-mentioned film-consumable paint, the micro-level unevenness also decreases. (The surface roughness seen visually is also lower than the initial value), which significantly reduces the frictional resistance.Furthermore, due to the effect of reducing the microscopic surface roughness, there is no foothold for bacteria and diatoms to adhere to it. , slime resistance is also significantly improved.

The macro surface roughness referred to here is BSRA
Based on the ship hull surface roughness measurement method proposed by (British Shipbuilding Research Association) and currently the most popular and used method in shipbuilding and ship-related fields. Regarding the method of measuring surface roughness using this BSRA method and the relationship between the above-mentioned paint film consumable paint and its surface roughness, there are already many publications and research reports, which will be described in detail here. Also, micro surface roughness is defined by JIS (Japanese Industrial Standards) & B 0
601 means the surface roughness.

In the present invention, PVC (P
igment Volume Concentration
on: The limit value of the constituent components of the paint excluding the vehicle, plasticizer, and solvent bone (and the proportion of the volume occupied by other antifouling agents, pigment bones, etc. in the paint film) is determined by the hydrolyzable resin used. Although it varies slightly depending on the contents of the antifouling agent, pigment, etc. to be blended, the results of checking with various blends are generally consistent, and PVC exists in a range of 20% by volume or less.

The present invention was completed based on this knowledge, and the gist thereof is that a triorganotin salt of an α,β-unsaturated acid-base acid dibasic acid constitutes a paint film-consumable antifouling paint. The vehicle is an acrylic copolymer resin containing as a constituent unit, and among the components constituting the paint, the proportion of the volume occupied by the antifouling agent and the pigment, excluding the vehicle, plasticizer, and solvent bone (hereinafter referred to as rPVCJ) The present invention relates to an antifouling paint for the bottom of a boat that reduces underwater frictional resistance, and is characterized in that the content of the antifouling paint is 20% by volume or less.

As the acrylic copolymer resin containing a triorganotin salt of an α,β-unsaturated acid-base acid dibasic acid as a constituent unit in the present invention, ordinary ones may be used, and particularly preferred ones include, for example. The general formula [R in the formula] and R2 are the same or different, and are a hydrogen atom or a lower alkyl group (methyl,
ethyl, etc.) and Ra is butyl, phenyl]. Examples include copolymers with acrylic compounds (such as acrylic compounds). In particular, those using unsaturated organotin compounds in which R3 is butyl (e.g. tributyltin methacrylate),
It has a more noticeable effect.

Further, these unsaturated organic tin compounds are used as a copolymer with a conventional unsaturated compound from the viewpoint of coating film properties. Acrylic compounds and vinyl compounds used as copolymers include methyl (meth)acrylate and ethyl (meth)acrylate.

Isopropyl (meth)acrylate, n-butyl (meth)acrylate, Isobutyl (meth)acrylate, (
2-Hydroxyethyl meth)acrylate.

Examples include 2-hydroxyethyl acrylate, styrene, vinyl acetate, vinyltoluene, acrylonitrile, and the like.

In addition, the antifouling agent, pigment, etc. to be blended in the present invention are comprised of the components of ordinary ship bottom antifouling paints, excluding the vehicle, plasticizer, and solvent.

For example, antifouling agents (cuprous oxide, cuprous rhodan, metallic copper, totibutyltin fluoride, bitributyltin oxide, tributyltin chloride, bis(tributyltin)-α
, α゛-dibromsuccinate triphenyltin hydroxide, triphenyltin acetate, triphenyltin chloride.

Triphenyltin fluoride, bis(triphenyltin)
-α,α“-organotin compounds such as dibromsuccinate and triphenyltin nicotinate, thiurams, dithiocarbamates, etc.), color pigments (titanium white, Bengara, carbon blank, zinc white, etc.), extender pigments ( Palite powder,
Clay, talc.

silica powder, etc.), and various other additives (anti-settling agents).

anti-foaming agents, leveling agents, etc.), and these components may be appropriately selected depending on the intended use of the coating material of the present invention, and may be blended in appropriate proportions.

The volume ratio (PVC) of the antifouling agent, pigment, etc. excluding the vehicle, plasticizer, and solvent, which is an essential condition in the present invention, is 20% by volume or less, but preferably the friction From the viewpoints of resistance reduction effect, improvement of slime resistance, painting workability, etc., it is preferable to select the amount within the range of 15% by volume or less.

Although the present invention is applicable to submerged parts of ships and offshore structures,
Of course, it goes without saying that the technique of the present invention can be used to reduce the frictional resistance between a coating film and seawater or water even in fields where antifouling properties are not required.

The paint of the present invention having the above-mentioned structure can reduce the frictional resistance with seawater by about 20% compared to conventional ship bottom antifouling paints. Even compared to dirty paints, it can be reduced by 2 to 6%. At the same time, a very excellent improvement in slime resistance was observed, and it can be said to be extremely useful from the point of view of practicality and economy.

Next, the present invention will be specifically explained with reference to Examples, Comparative Examples, and Test Examples. In addition, unless otherwise specified, "parts" means parts by weight. However, the present invention is not limited to the technical content of these specific examples.

Resin Production Example 1 67 parts of pheasant roll was added to a four-bottle flask equipped with a reflux condenser, a dropper'o-), and a stirrer, and the temperature was maintained at 80-85°C. A mixed solution of 70 parts of tributyltin methacrylate, 30 parts of methyl methacrylate, and 1.2 parts of α1α゛-azobisisobutyronitrile was added dropwise to this solution over 4 hours, and the mixture was kept warm for an additional 3 hours. The resulting resin solution was Varnish A having a solid content of 60.1%, a viscosity of 4.0 poise, and a resin number average molecular weight of 15,000.

Resin Production Example 2 Using the same reaction apparatus as in Production Example 1, 40 parts of pheasant roll was added to a four-bottle flask and maintained at 80 to 85°C. A mixed solution of 60 parts of tributyltin hemethacrylate, 30 parts of methyl methacrylate, 10 parts of ethyl acrylate, and 1.0 part of benzoyl peroxide was added dropwise to this solution over 4 hours, and the mixture was kept warm for an additional 3 hours.

After that, 27 parts of pheasant roll was added to give a solid content of 59.7%.

Varnish B having a viscosity of 6.5 poise and a resin number average molecular weight of 16,000 was obtained.

Examples 1 to 6 and Comparative Examples 1 to 4 Ship bottom antifouling paints of various Examples and Comparative Examples (Table 1) are prepared by using the paint components shown in Table 1 and dispersing them in a ball mill. The specific contents of some of the ingredients are as follows.

1 Sanfu A, Varnish B Salt 1 shown in Resin Production Examples 1 and 2], Product name manufactured by UI Dochiryuka Kogyo Co., Ltd. [Using ADEKA Chloride Rubber CR-10J.

Salt Shin! Hill J''l'u Vinyl chloride-ruhinyl isobutyl ether copolymer. Uses the product name "Ralofrenox MP45 J" manufactured by West German BASP.

Testing Using the ship bottom antifouling paints of various Examples and Comparative Examples (Table 1), tests were conducted according to the following method.

(1) Paint film surface roughness measurement stylus-type surface roughness measuring instrument specified in the Japanese Industrial Standards (JIS) NO, B 0651 (manufactured by Koita Institute, trade name: Universal surface profile measuring instrument MODEL 5E) -3CJ) and the measurement method indicated in JIS 1lkLB 0601 to determine the coating surface roughness (center line average roughness Ra).
) are measured and compared.

Paint film surface roughness External diameter 20CI11. A steel disk having a thickness of 3 fl is coated with a commercially available vinyl cool type ship bottom paint twice, and then coated with ship bottom antifouling paints of various Examples and Comparative Examples (Table 1) twice.

Painting on steel discs should be done once a day, and after the final painting, 5 times should be applied indoors.
Dry in the sun. After drying for 5 days, the coating film surface roughness (center line average roughness R
a) Measure ).

After the measurement, the sample 3 was attached to the rotating shaft 4 of the testing machine 1 shown in FIG. 1 and immersed to a depth of about 20 cm below the seawater level, and rotated at a constant speed. The rotation speed at this time is 1200r, p,
m, and the circumferential speed at the tip is approximately 1'1.5 m/5ec.
(approximately 24.4 knots).

After spinning for about 3 months without rest, I pulled it up and washed it with water.
After drying, the coating film surface roughness (center line average roughness, Ra
)) to measure.

The results are shown in Table 2.

(2) Seawater friction resistance measurement (Kansai Shipbuilding Association Journal, No. 136
No. 31-32: Osamu Yoda et al., "Research on Underwater Friction Resistance Depending on the Condition of the Paint Film," September 1970 issue).

The test machine described in the above-mentioned document by Fuchi Fuchi is used, and the outline of the test machine is shown in the attached drawing, Figure 2 (Test machine-2).

Here, the volume of the aquarium 1 is 501, and natural seawater 2 is poured into it to a depth of 30 cm. Sample 3 has a diameter of 20 cm.

It is a steel disc with a thickness of 3 fins coated with various antifouling paints on the bottom of the ship, and is exactly the same as the one used in "(1) Paint film surface roughness measurement." This sample 3 was attached to the rotating shaft 4 and immersed to a point 10a++ below the sea surface, and the power sources (A, C, 20
0V) 5 and a motor 7 connected to a tachograph 6 to rotate at a constant speed (at this time, a plate 8 is provided to prevent waves from forming on the sea surface). Then, the resistance at that time is detected as a torque value using a torque meter 9 and a recorder 10.

The rotation speed is continuously variable up to 2500r, p, m,
This corresponds to a peripheral speed of approximately 26 m/sec (approximately 50 knots) at the tip and approximately 13 rr+/sec (approximately 25 knots) at the center.

Comparison of the frictional resistance in seawater against friction resistance is not done directly using the torque value measured by the tester shown in Figure 2, but by calculating a representative value for each sample, that is, the frictional resistance coefficient cr. Make a comparison.

The torque value of a disk rotating in seawater is theoretically calculated from the sample size, rotation speed, etc., and is expressed by the following equation.

R: Radius of the disc (m) b = Thickness of the disc (m) T: Unit volume weight of seawater (kg/n?) Cf: Coefficient of frictional resistance g: 9.8 m/sec” Circumference of the two discs speed (m/5ec).

On the other hand, if P is the rotational speed (r, p, m, ), then υ=
2 πRX − 0, the above equation becomes as follows, and by substituting each value, T = 1.2 Xl0−'Cf P”.

Based on the data actually obtained, the relationship between T and P is shown in Figure 3. In FIG. 3, since the slope of the straight line is 2, the relationship between T and P is Tc-CP'', and after all, Cf can be used to compare the measured values.

Therefore, as a standard, a steel disc was coated with two coats of a commercially available vinyl cool ship bottom paint, and then two coats of a commercially available ship bottom antifouling paint (Comparative Example 5 above). The Cf value of the comparative example was calculated and compared based on the ratio of Cf to Cro of the standard plate. The sample test plate used here is exactly the same as that used in "(1) Paint film surface roughness measurement".

After the final coating of the sample test board, it was dried indoors for 5 days, and then the torque value was determined as described above.

In addition, as was carried out in "(1) Paint film surface roughness measurement" after the measurement, 120 Or, p,
After rotating at +a, the torque value was determined again in the manner described above.

The calculated cr value of each example and comparative example and the ratio (C
f /Cfo ) are shown in Table 3.

(3) Antifouling property test A commercially available vinyl cool ship bottom paint was applied three times to a 300xlOOX1.6 ■■ Zandoplast-treated steel plate, and then the paints of various examples and comparative examples were applied two times for 3 days. After drying indoors, they were hung on a raft at Uno Port, Tamano City, Okayama Prefecture, to a depth of 0.5 m and immersed (soaking started in November 1980) for 6 months.

After 9 months, the state of adhesion of slime (marine microorganisms) and flora and fauna (marine flora and fauna) was observed. The result is the fourth
Shown in the table.

In Table 4, the evaluation values for (marine) flora and fauna are based on the surface area of the test piece being taken as 100. , represents the percentage of area covered by marine plants such as Ushiganori. Furthermore, the evaluation value for slime (marine microorganisms) represents the percentage of the area covered by marine microorganisms such as diatoms, bacteria, and molds as seen with the naked eye.

Table 1 Age

[Brief explanation of the drawing]

Figure 1 shows the testing machine used to test the surface roughness of the paint film after dipping.
1 is a schematic diagram, Figure 2 is a schematic diagram of test v1-2 used to measure seawater frictional resistance, and Figure 3 is a diagram showing the torque value measured using the testing machine in Figure 2 and the rotational speed P of the disc. This is a graph showing the relationship between 1 is a seawater tank, 2 is seawater, 3 is a sample, 4 is a rotating shaft, 5
is a power source, 6 is a tachograph, and 7 is a motor. Patent applicant Nippon Paint Co., Ltd. Agent Patent attorney Takuo Akaoka Figure 3? log P(r, p-m)

Claims (1)

[Scope of Claims] +11 The vehicle is an acrylic copolymer resin containing a triorganotin salt of an α,β-unsaturated unsaturated acid-base acid dibasic acid as a constituent unit, and among the components constituting the paint, the vehicle, Pigment Volume Co
centration: hereinafter referred to as pvc) is 2
An antifouling paint for the bottom of a boat that reduces underwater frictional resistance and is characterized by having a content of 0% by volume or less. (2) The underwater frictional resistance reducing antifouling paint for a ship bottom according to item 1, wherein the triorganotin salt of an α,β-unsaturated unsaturated acid-base acid dibasic acid accounts for 965% by weight or more of the acrylic copolymer resin.