JPH05179171A - Conductive layer for preventing adhesion of marine organism - Google Patents

Abstract

PURPOSE:To obtain the title conductive layer excellent in, e.g. resistance to electrolysis by seawater by forming the under layer from a specified copolymer resin as binder and a conductive filler in a conductive layer consisting of an upper layer and an under layer. CONSTITUTION:In a conductive layer consisting of an upper layer and an under layer, the under layer is formed from: a binder comprising a copolymer resin which consists at least of 80-98.5wt.% methyl methacrylate component, 1-15wt.% of at least one monomer component selected from among (meth)acrylic esters (except methyl methacrylate) (e.g. butyl methacrylate), and 0.5-5wt.% of at least one monomer component selected from among an unsaturated carboxylic acid, a phosphoric ester, a sulfonic ester, an aminated vinyl monomer, and an epoxidized vinyl monomer (e.g. maleic anhydride), the total of these components accounting for at least 90wt.% of the copolymer; and a conductive filler (e.g. graphite).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the prevention of adhesion of marine organisms by energizing the water contact part of an object that comes into contact with seawater, such as a ship, an offshore / undersea structure, a seawater guide / drainage facility, a seawater storage tank, or a quay wall. Regarding technology. More specifically, a conductive layer is provided so as to cover at least the water contact part (hereinafter simply referred to as "water contact part") of an object that comes into contact with seawater, and a direct current is applied to this conductive layer.
The present invention relates to the conductive layer in the technique of preventing the adhesion of marine organisms by electrolyzing seawater using the layer as an anode to generate chlorine, hypochlorous acid, etc. which marine organisms dislike.

[0002]

2. Description of the Related Art Conventionally, the wetted part of an object that comes into contact with seawater is coated with an antifouling paint containing an antifouling agent such as an organotin compound, and a gradually eluting antifouling agent prevents the adhesion of marine organisms. Is being done. However, since the elution rate of the antifouling agent cannot be adjusted and the amount of the antifouling agent contained in the paint is limited, repainting work is required, but it is difficult to repaint the wetted part and There is a risk of environmental pollution due to the elution of pollutants.

As a technique for preventing the adhesion of marine organisms in place of the above antifouling paint, a technique for preventing the adhesion of marine organisms by electrolysis of seawater has been developed.

To explain this in more detail, a conductive layer is provided on the water contact portion of the marine structure via an insulating layer, and this conductive layer is used as an anode, and a cathode is provided in seawater at an appropriate distance. The conductive layer is divided into two or more compartments, one part (one or more compartments) is used as an anode, and the rest is used as a cathode.
Apply a direct current of ² or less to electrolyze seawater,
It is intended to prevent the adhesion of chlorine, hypochlorous acid, etc., which marine organisms dislike, by generating them near the conductive layer that is the anode.

The above-mentioned conductive layer is provided as a coating layer of a conductive coating material or a composite layer of a coating layer of a conductive coating material and another material. Conventionally, the conductive coating layer and the conductive layer using the same are as follows. Something like is known.

(1) A conductive filler made of any one of graphite powder, carbon black, magnetite, manganese dioxide, and a platinum group metal is mixed with an epoxy resin.
A mixture containing 50% or more by volume of a coating material containing an unsaturated polyester resin, an acrylic resin, a phenol resin, or a urethane resin as a matrix (Japanese Patent Laid-Open No. 63-
No. 101464).

(2) A conductor wire embedded in an electrically conductive film composed of an electrically conductive filler of a metal such as carbon, magnetite, manganese dioxide, or platinum group and an organic binder (Japanese Patent Laid-Open No. 63-103789). Issue).

(3) Powder of conductive filler such as nickel, copper, titanium, niobium, magnetite and manganese dioxide,
Fillers, flakes and other small pieces mixed in an organic binder such as epoxy resin, vinyl resin, unsaturated polyester resin, acrylic resin, phenol resin, urethane resin, vinyl ester epoxy resin, etc. are provided in multiple layers,
One in which the specific resistance is increased stepwise from the inner side to the outer side (JP-A-64-87791).

[0009]

However, in the conductive layer formed by using the above-mentioned conventional conductive paint for preventing adhesion of marine organisms, seawater easily permeates and diffuses into the coating film constituting the conductive layer, and the electrolysis of seawater is also performed. Due to the contact with substances such as chlorine and hypochlorous acid generated by the above, deterioration and damage are likely to occur, and there is a problem of poor resistance to seawater electrolysis.

Specifically, cracking of the coating film, peeling of the coating film, detachment of the conductive filler, and loss of the conductive filler or conductive wire are likely to occur, resulting in a decrease in conductivity of the conductive layer. However, there is a problem that the prevention of adhesion of marine organisms cannot be maintained for a long period of time over a wide area of the water contact part.

The present invention has been made in view of these problems, and imparts a barrier property for preventing permeation and diffusion of seawater and a resistance to an electrolysis product of seawater,
It is an object of the present invention to provide a conductive layer for preventing adhesion of marine organisms, which has excellent resistance to electrolysis of seawater and can prevent adhesion of marine organisms over a wide range for a long period of time.

[0012]

Therefore, according to the present invention, in a conductive layer consisting of two layers, an upper layer and a lower layer, the lower layer is a copolymer resin comprising at least the following (A), (B) and (C): And the proportions of (A), (B), and (C) to the whole are 80 to 98.5% by weight, 1 to 15% by weight, and 0.5 to 5% by weight, respectively, and (A) + (B) +
(C) is a conductive layer for preventing adhesion of marine organisms, which comprises a copolymer resin having 90% by weight or more of the whole as a binder, and the binder and a conductive filler. (A) Methyl methacrylate portion. (B) At least one monomer moiety selected from acrylic acid esters and methacrylic acid esters (excluding methyl methacrylate). (C) At least one monomer moiety selected from unsaturated dicarboxylic acids, phosphoric acid esters, sulfonic acid esters, amino group-containing vinyl monomers and epoxy group-containing vinyl monomers.

The present invention will be further described in detail.

(A) Methyl methacrylate (hereinafter referred to as MMA) in the copolymer resin used as the lower layer binder
The proportion of the portion is 80 to 98.5% by weight, preferably 85.
~ 95% by weight. If this ratio is less than 80% by weight,
The specific resistance of the obtained conductive layer tends to increase. Conversely, 98.
If it exceeds 5% by weight, the solubility of the copolymer resin in the solvent tends to be lowered.

The proportion of at least one monomer portion selected from (B) acrylic acid ester and methacrylic acid ester (excluding MMA) in the copolymer resin used as the lower layer binder is 1 to 15% by weight, preferably Is 2 to 5% by weight. If this proportion is less than 1% by weight, the solubility of the copolymer resin in the solvent tends to be lowered. Conversely 1
If it exceeds 5% by weight, the resistance to permeation and diffusion of seawater decreases.

Examples of the monomer forming (B) include ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate,
Tridecyl methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, benzyl methacrylate, 2-hydroxyethyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, acrylic Tridecyl acid, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, benzyl acrylate, acrylic acid-
2-hydroxyethyl etc. are mentioned. These may be used alone or in combination of two or more.

The copolymer resin used as the lower layer binder in the present invention is (C) unsaturated dicarboxylic acid, sulfonic acid ester monomer, phosphoric acid ester monomer, amino group-containing vinyl monomer and epoxy group-containing vinyl. Although at least one kind of monomer portion selected from monomers is introduced, the proportion of (C) in the copolymer resin is 0.5 to 5% by weight, preferably 1 to 3% by weight. %. This ratio is 0.5
If it is less than wt%, the adhesion to a metal or metal oxide having a low specific resistance and the dispersibility of the conductive filler will be reduced. Conversely 5
When the content is more than 10% by weight, the resistance of the coating film to electrolysis of seawater is lowered and the barrier property is lowered to make it difficult to sufficiently prevent permeation and diffusion of seawater.

The unsaturated dicarboxylic acids refer to unsaturated dicarboxylic acids, unsaturated dicarboxylic acid anhydrides, unsaturated dicarboxylic acid esters, and unsaturated dicarboxylic acid salts. Examples of unsaturated dicarboxylic acids include maleic acid and itaconic acid. As the unsaturated dicarboxylic acid anhydride such as fumaric acid,
Examples of unsaturated dicarboxylic acid salts such as maleic anhydride and itaconic anhydride include monovalent metals, ammonia,
Examples thereof include salts such as amines. Further, examples of the unsaturated dicarboxylic acid ester include esters of unsaturated dicarboxylic acid such as methyl, ethyl, propyl, butyl, and 2-ethylhexyl, and the alkyl group preferably has about 1 to 8 carbon atoms. The ester may be a monoester, a diester or a mixture thereof.

Examples of the sulfonic acid ester monomer include vinyl sulfonic acid, 2-sulfoethyl methacrylate, 2-acrylamido-2-methylpropane sulfonic acid, and allylalkyl sulfosuccinic acid Na.

As the phosphoric acid ester monomer, for example, 2
Examples include acid phosphooxyethyl methacrylate, 2 acid phosphooxypropyl methacrylate, diphenyl 2-methacryloyloxyethyl phosphate, 3chloro 2 acid phosphooxypropyl methacrylate, and acid phosphooxypolyoxyethylene glycol monomethacrylate.

As the amino group-containing vinyl monomer, for example, N, N-dimethylaminoethyl methacrylate,
N, N-diethylaminoethyl methacrylate, N, N
-Dimethylaminopropyl acrylamide, t-butyl aminoethyl methacrylate, etc. are mentioned.

Examples of the epoxy group-containing vinyl monomer include glycidyl methacrylate, allyl glycidyl ether, glycidyl acrylate, and glycidyl-P-vinylbenzoate.

These may be used alone or in combination of two or more.

The copolymer resin used as the binder of the lower layer includes, in addition to the above-mentioned (A) to (C), other monomers copolymerizable with the monomers forming (A) to (C). It is also possible to introduce part (D) at less than 10% by weight, preferably less than 5% by weight.

Explaining the monomer forming (D), for example, in order to reduce the surface frictional resistance when a coating film is formed, (D) is a monomer having a silicon atom, a fluorine atom is added. It is preferable that the monomer has.
Examples of these monomers include silicon macromonomers (such as AK-5 and AK-30 manufactured by Toagosei Co., Ltd.), 3
-Methacryloxypropyl methoxysilane, vinylidene fluoride, vinyl fluoride and the like.

Further, in order to improve the flexibility of the coating film and prevent damage such as cracking and peeling of the coating film due to expansion and contraction of the object to be coated, vibration, etc., an alkyl ether side chain having 3 or more carbon atoms is used. Preferred are alkyl vinyl ethers, ethylene and the like.

The copolymer resin used as the binder in the lower layer preferably has a weight average molecular weight of 20,000 to 120,000, more preferably 30,000 to 100,000. If the weight average molecular weight is less than 20,000, the strength and durability of the coating film tend to be insufficient, and if it exceeds 120,000, the solvent solubility and the coating workability of the coating material tend to be low.

The copolymer resin used as the binder in the lower layer is (A) to (C) or (A) to which has been described above.
It is obtained by copolymerizing the monomer forming (D).
The method of this copolymerization is not particularly limited, and for example, solution polymerization, suspension polymerization, emulsion polymerization, bulk polymerization and the like can be performed. Specifically, an ordinary apparatus for carrying out MMA polymerization reaction,
It can be performed according to conditions, operations and procedures. Also, the polymerization is a polymerization reaction initiated in a homogeneous or heterogeneous system,
As the polymerization progresses, it may change to a heterogeneous system or a homogeneous system from the middle.

The conductive filler in the lower layer is mixed in a shape such as a powder, a small piece, or a short fiber shape that is easy to disperse.
There is no particular limitation as long as it is a solid substance having conductivity.
One or a combination of two or more substances or shapes can be used. Specific examples of the substance include graphite (natural graphite, artificial graphite), carbon black (gas black such as acetylene black,
Examples include carbons such as oil black and naphthalene black), magnetite, platinum group metals and other metals and alloys having conductivity. Among these, carbons are practical in terms of stability of the paint and cost. Further, in order to reduce the specific resistance of the conductive layer, it is preferable to use two or more kinds of conductive fillers having different average particle sizes in combination.

If the blending ratio of the conductive filler is too high, the coating workability of the conductive paint, the coating film forming property, the storage stability, etc. are deteriorated, and the barrier property of the resulting coating film and the conductive filler are obtained. Retention, adhesion to the substrate, strength, etc. are reduced. On the other hand, if the blending ratio of the conductive filler is too small, it becomes difficult to obtain conductivity when the coating film is formed, or blistering occurs in a part of the coating film during seawater electrolysis. The mixing ratio of the conductive filler may be appropriately selected so that the properties such as the coating workability of the conductive paint and the barrier properties of the resulting coating film and the conductivity of the coating film are harmonized. The volume ratio (X) of the conductive filler to the total amount of the conductive filler and the binder is preferably 5 to 70% by volume. Specifically, when X is lowered, it is preferable to use a conductive filler having a high oil absorption such as Ketjen Black. Conversely, when X is increased, an oil absorption such as graphite is preferably used. It is preferable to use a conductive filler having a small value. Here, X is
It is a value represented by the following equation (1).

[0031]

[Equation 1] Next, the upper layer is not particularly limited, for example, vinyl resin, epoxy resin, unsaturated polyester resin, acrylic resin, phenol resin, a resin such as a urethane resin as a binder, a conductive layer containing a conductive filler Can be used. Although the specific resistance of the upper layer is not particularly limited,
When the resistivity is larger than that of the lower layer, the concentration of current density in the vicinity of the power source connecting portion of the lower layer can be easily prevented, and a uniform marine organism adhesion preventing effect can be obtained over a wide range, which is preferable.

[0032]

【Example】

Examples 1 to 25, Comparative Examples 1 to 6 Copolymer resin solutions of various compositions shown in Table 1 were diluted with an equivalent weight mixed solvent of toluene and methyl isobutyl ketone, and graphite having an average particle size of 5 μm was dried in the coating film. Was added so that the volume concentration thereof was about 60% by volume to obtain a conductive coating material for the lower layer.

On the other hand, as the conductive paint for the upper layer, a vinyl resin was dissolved in the above-mentioned solvent, and graphite having an average particle diameter of 2 μm was adjusted so that the volume concentration in the dry coating film was about 35% by volume.

Using these conductive paints, a conductive layer was manufactured by the following procedure, and an iron pipe of 1 inch long and 1 m long was hooked down at a distance of about 30 cm from it, and the iron pipe was energized as a cathode to prevent electricity in Nagasaki Bay. A stain durability test was conducted to evaluate the stainproof performance. The energization amount is 40 mA. A width of 35 cm, a length of 100 cm, and a thickness of 1 cm are parallel to one corner of one side of the acrylic plate, and the width is 1 cm and the length is 33 c.
m, and a copper foil having a thickness of 100 μm was attached. A single-core vinyl-coated copper wire was soldered in the vicinity of the center of the copper foil to form a conducting wire. Covering the copper foil, the thickness of the conductive coating after drying is 350μ
The conductive paint for the lower layer was airlessly coated so that the thickness became m. Further, an electrically conductive coating material for the upper layer was applied thereon by airless coating so that the thickness of the electrically conductive coating film after drying would be 350 μm. After coating, it was dried for 7 days and then subjected to an electrolytic durability test.

The test results are shown in Table 2, and it is clear that the present invention significantly improves the durability of the conductive layer and is effective in improving the economical efficiency of the electrolytic antifouling system using the conductive layer.

[0036]

[Table 1]

[0037]

[Table 2] Examples 26 to 30 and Comparative Example 7 The upper layer conductive paint and the lower layer conductive paint used in Examples 1, 14, 16, 19, 22, and Comparative Example 1 were applied to a 40-ton class passenger ship, respectively, and small in size. I conducted a ship experiment. The dimensions of the passenger ship are
The length is 20m, the width is 2.5m, and the depth is 1.5m. From the outer plate to the bottom of the ship, the center of the bottom and the outer plate are divided into 6 sections through an insulating film, and the opposite port and starboard sections are separated. One set is used, and three sets are used as a pair, which is a polarity switching method for switching the anode and the cathode at regular time intervals (for example, 2 hours). The average current density is constant in all sections, and the total energization amount is about 5
It is A. The evaluation was carried out by a two-year antifouling durability test. As shown in Table 3, the effectiveness of the present invention was confirmed.

The procedure for applying a conductive coating film on a passenger ship is as follows.

After the outer shell of the hull was blasted, an epoxy-based insulating coating material was applied to an average film thickness (dry) of 400 μm.

A copper foil having a width of 3 cm and a thickness of 100 μm was attached to the upper end of each partition outer plate in parallel with the deck, and a vinyl-coated copper wire was soldered in the vicinity of the center to form a current-carrying wire.

The copper foil is also covered and the film thickness after drying is 350 μm.
The conductive paint for the lower layer was airlessly coated so as to have m.

Further, an electrically conductive coating material for the upper layer was airless coated thereon so that the dry film thickness was 350 μm. The same conductive paint as in Example 1 was used for the upper layer.

After coating, the product was dried for 7 days and then energized from a DC power supply unit to start an actual ship test in the port of Nagasaki.

[0044]

[Table 3] Examples 31 to 35, Comparative Example 8 In order to continuously energize the energization method, a pipe of 1 inch and 10 m was attached to the center of the bottom of the ship so as to maintain insulation with the hull and used as a cathode. 30, the same as in Comparative Example 7, a two-year antifouling durability test was performed.

Since the energizing amount is the same, the current density is 1
/ 2. The result is similar to the polarity switching method described above,
We were able to confirm the effectiveness.

[0046]

The present invention is as described above. Since the conductive layer of the present invention has excellent resistance to seawater electrolysis, the prevention of adhesion of marine organisms by electrolysis of seawater over a wide range. It is possible to do it for a long time.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // B63B 59/04 A 9035-3D

Claims (3)

[Claims] 1. A conductive layer consisting of two layers, an upper layer and a lower layer, wherein the lower layer is a copolymer resin comprising at least the following (A), (B) and (C), and (A), (B), ( The ratio of C) to the whole is 80-98.5% by weight, 1 respectively.
-15% by weight, 0.5-5% by weight, and (A) +
A conductive layer for preventing adhesion of marine organisms, characterized in that (B) + (C) is a copolymer resin having 90% by weight or more of the whole as a binder, and is composed of the binder and a conductive filler. (A) Methyl methacrylate portion. (B) At least one monomer moiety selected from acrylic acid esters and methacrylic acid esters (excluding methyl methacrylate). (C) At least one monomer moiety selected from unsaturated dicarboxylic acids, phosphoric acid esters, sulfonic acid esters, amino group-containing vinyl monomers and epoxy group-containing vinyl monomers. 2. The volume ratio (X) of the conductive filler to the total of the conductive filler and the binder in the lower layer is 5 to 7.
The conductive layer according to claim 1, which is 0% by volume. 3. The conductive layer according to claim 1, wherein the conductive filler in the lower layer is at least one selected from graphite powder and carbon black.