KR20210003818A - Copolymer for antifouling paint composition, antifouling paint composition containing the copolymer - Google Patents

Abstract

An object of the present invention is to provide an antifouling coating composition that has good storage stability of the paint, and the resulting antifouling coating film does not have any abnormalities (whitening, peeling, cracks, etc.) of the coating film in seawater for a long period of time, and maintains stable coating film solubility and antifouling effect. To
According to the present invention, as a copolymer for an antifouling coating composition obtained by copolymerizing a mixture of a monomer (a) and a polymerizable unsaturated monomer (b) other than the monomer (a), the monomer (a) is a general formula (1) Represented by, and the monomer (b) contains 2-methoxyethyl methacrylate,
The content of the monomer (a) accounts for 5 to 45% by mass of the total mass of the monomer (a) and the monomer (b), and the content of 2-methoxyethyl methacrylate is the monomer (a) and the above There is provided a copolymer for an antifouling coating composition accounting for 55 to 95% by mass of the total mass of the monomer (b).

Description

Copolymer for antifouling paint composition, antifouling paint composition containing the copolymer

The present invention relates to a copolymer for an antifouling coating composition, and to an antifouling coating composition containing the copolymer.

Aquatic contaminated organisms such as barnacles, western tubeworms, pearl mussels, moss insects (Bugula neritina), snails, greens, snails, slime, etc. By being attached to the surface of the underwater structure, the function of these ships or underwater structures is impaired and the appearance is damaged. In particular, in the case of ships, the resistance increases, resulting in a decrease in speed or an increase in fuel economy, resulting in greater damage.

Therefore, nowadays, antifouling paints made of triorganosilyl group-containing copolymers as a vehicle are used on the surface of underwater structures such as ships (especially the bottom of the ship), fishing tools such as fishing nets, fishing net accessories, and power pipes. A method of applying and forming an antifouling coating film to prevent such damage is widely practiced.

In the triorganosilyl group-containing copolymer, the triorganosilyl ester portion is hydrolyzed in seawater, and the copolymer gradually dissolves in seawater to renew the surface of the coating film, thereby exhibiting an antifouling effect.

As the triorganosilyl group-containing copolymer, a triorganosilyl ester-containing monomer consisting of a branched alkyl group or aryl group such as triisopropylsilyl ester and t-butyldiphenylsilyl ester, and 2-methoxy (meth)acrylate Triorganosilyl group-containing copolymers (Patent Documents 1 to 4) formed by copolymerizing an alkoxyalkyl ester of (meth)acrylic acid such as ethyl have been proposed.

However, since the antifouling paint using this triorganosilyl group-containing copolymer as a medium has poor storage stability, it has been proposed to use a dehydrating agent such as ethyl silicate or anhydrite in the paint (Patent Documents 5 to 6). However, it is not sufficient, and there is a problem in that storage stability is deteriorated when the humidity at the time of manufacture of the paint is high.

In addition, these triorganosilyl group-containing copolymers do not sufficiently dissolve the coating film in the initial stage, and there is a problem that the coating film is whitened or fouling organisms adhere during the design period or the initial anchoring period.

Japanese Patent Laid-Open Publication No. Hei 7-102193 Japanese Patent Application Laid-Open No. 2001-226440 Japanese Patent Laid-Open Publication No. 2005-82725 Japanese Patent Application No. 2016-062432 Japanese Patent Laid-Open Publication No. Hei 7-18216 Japanese Patent Application Laid-Open No. Hei 9-48948

An object of the present invention is to provide an antifouling coating composition that has good storage stability of the paint, and the resulting antifouling coating film does not have any abnormalities (whitening, peeling, cracks, etc.) of the coating film in seawater for a long period of time, and maintains stable coating film solubility and antifouling effect. do.

According to the present invention, as a copolymer for an antifouling coating composition obtained by copolymerizing a mixture of a monomer (a) and a polymerizable unsaturated monomer (b) other than the monomer (a), the monomer (a) is a general formula (1) And the monomer (b) contains 2-methoxyethyl methacrylate, and the content of the monomer (a) is 5 to 45% by mass of the total mass of the monomer (a) and the monomer (b) And the content of the 2-methoxyethyl methacrylate accounts for 55 to 95% by mass of the total mass of the monomer (a) and the monomer (b).

As a result of intensive research, the present inventors found that using a copolymer (A) obtained by containing a specific amount of 2-methoxyethyl methacrylate in a monomer (b) copolymerized with a monomer (a) of a specific configuration as a medium Even when manufactured under a high degree of conditions, the storage stability of the paint is very good, the coating film has no abnormality in the coating film such as whitening, peeling, cracks, etc. for a long time in seawater, and an antifouling coating composition that maintains stable coating film solubility and antifouling effect for a long time can be obtained. Finding out that there is, came to the present invention.

Hereinafter, the present invention will be described in detail.

1. Antifouling paint composition

The antifouling coating composition of the present invention contains a copolymer (A) for an antifouling coating composition and an antifouling agent (B).

1-1. Antifouling coating composition copolymer (A)

The copolymer (A) for an antifouling coating composition is a triorganosilyl group-containing copolymer, and is obtained by copolymerizing a mixture of a monomer (a) and a monomer (b). The copolymer (A) contains monomer units derived from monomers (a) to (b).

<Monomer (a)>

The monomer (a) is a methacrylic acid triorganosilyl ester monomer, and is represented by General Formula (1).

[Formula 1]

(In the formula, R ¹ is a methyl group, R ² , R ³ , R ⁴ are selected from a C 3 to C 8 branched alkyl group and a phenyl group, and may be the same or different)

In the present invention, as a monomer (a) represented by the general formula (1), for example, triisopropylsilyl methacrylate, triisobutylsilyl methacrylate, tris-butylsilyl methacrylate, tri methacrylic acid Isoamylsilyl, tris(2-ethylhexyl)silyl methacrylate, triphenylsilyl methacrylate, diisopropylisobutylsilyl methacrylate, diisopropylisoamylsilyl methacrylate, diisopropyl methacrylate (2-ethylhexyl)silyl, diisopropylphenylsilyl methacrylate, diisopropylcyclohexylsilyl methacrylate, t-butyldiisopropylsilyl methacrylate, t-butyldiisobutylsilyl methacrylate, methacrylate T-butyldiisoamylsilyl acrylate, t-butyldiphenylsilyl methacrylate, and the like, preferably t-butyldiphenylsilyl methacrylate and triisopropylsilyl methacrylate, particularly preferably Is triisopropylsilyl methacrylate. Each of these monomers is used in one or two or more kinds.

<Monomer (b)>

The monomer (b) is a polymerizable unsaturated monomer other than the monomer (a), and is copolymerizable with the monomer (a). In the present invention, it is an essential requirement that the monomer (b) contains 2-methoxyethyl methacrylate, and the coating composition obtained by the monomer (b) containing 2-methoxyethyl methacrylate in a specific amount The storage stability is very good, the coating film does not cause any abnormality in the coating film such as whitening, peeling, cracks, etc. for a long period of time, and exhibits a technical effect of maintaining stable coating film solubility and antifouling effect.

The monomer (b) may contain only 2-methoxyethyl methacrylate, or may contain a monomer other than 2-methoxyethyl methacrylate. As monomers other than 2-methoxyethyl methacrylate, the following are mentioned, for example.

Triisopropylsilyl acrylate, triisobutylsilyl acrylate, tris-butylsilyl acrylate, triisoamylsilyl acrylate, tris(2-ethylhexyl)silyl acrylate, triphenylsilyl acrylate, diisopropyl isobutylsilyl acrylate, acrylic acid Diisopropylisoamylsilyl, acrylic acid diisopropyl (2-ethylhexyl)silyl, acrylic acid diisopropylphenylsilyl, acrylic acid diisopropylcyclohexylsilyl, acrylic acid t-butyldiisopropylsilyl, acrylic acid t-butyldiiso Triorganosilyl acrylic acid esters such as butylsilyl, t-butyldiisoamylsilyl acrylate, and t-butyldiphenylsilyl acrylate.

Methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid Phenyl, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-methoxyethyl acrylate, 2-methoxyethyl (meth)acrylate Propyl, 4-methoxybutyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, polyethylene glycol methyl ether (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc. Meth)acrylic acid esters.

Versatic acid zinc (meth)acrylate, versatic acid magnesium (meth)acrylate, versatic acid copper (meth)acrylate, octylic acid zinc (meth)acrylate, octylic acid magnesium (meth)acrylate, Copper octylate (meth)acrylate, zinc laurate (meth)acrylate, magnesium laurate (meth)acrylate, copper laurate (meth)acrylate, zinc stearate (meth)acrylate, magnesium stearate ( (Meth)acrylic acid metal pendants such as meth)acrylate and copper stearate (meth)acrylate, and metal (meth)acrylates such as zinc (meth)acrylate and copper (meth)acrylate.

Vinyl compounds having functional groups such as vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl benzoate, vinyl butyrate, butyl vinyl ether, lauryl vinyl ether, and N-vinylpyrrolidone.

-Aromatic compounds such as styrene, vinyl toluene, and α-methylstyrene.

Dialkyl ester compounds of unsaturated dibasic acids such as dimethyl maleate, dibutyl maleate, and dimethyl fumarate.

Other copolymerizable monomers other than 2-methoxyethyl methacrylate are used in one or more than one type, respectively, preferably (meth)acrylic acid esters, and particularly preferably methyl (meth)acrylate.

The mass ratio of the content of 2-methoxyethyl methacrylate in the monomer (b) is preferably 0.75 to 0.95, more preferably 0.8 to 0.95, and specifically, for example, 0.75, 0.8, 0.85, 0.9, It is 0.95, and it may be in the range between any two numerical values illustrated here.

<Synthesis of copolymer (A)>

The copolymer (A) used for the antifouling coating of the present invention can be obtained by copolymerizing a mixture of a monomer (a) and a monomer (b). The copolymerization is carried out, for example, in the presence of a polymerization initiator.

The content of the monomer (a) in the mixture is 5 to 45 mass%, preferably 10 to 40 mass%, and more preferably 15 to 35 mass%. When the content of the monomer (a) is 5 to 45% by mass, the resulting antifouling coating composition has very good coating stability, the coating film does not cause abnormalities such as whitening, peeling, cracks, etc. for a long time in seawater, and stable coating film solubility from the beginning. And antifouling performance can be maintained. Specifically, this content is 5, 10, 15, 20, 25, 30, 35, 40, 45 mass%, for example, and may be in a range between any two numerical values exemplified herein.

The content of 2-methoxyethyl methacrylate in the mixture is 55 to 95% by mass, preferably 60 to 90% by mass, and more preferably 60 to 85% by mass. When the content of 2-methoxyethyl methacrylate is 55 to 95% by mass, the coating film formed using the obtained antifouling coating composition has good coating film solubility and antifouling effect from the beginning in seawater, and whitening, peeling, cracking, etc. No abnormality occurs in the coating film, and stable coating film solubility and antifouling effect can be maintained for a long time. Specifically, this content is, for example, 55, 60, 65, 70, 75, 80, 85, 90, 95% by mass, and may be within a range between any two numerical values exemplified herein.

The total content of the monomer (a) and 2-methoxyethyl methacrylate is 60 mass% or more, preferably 70 mass% or more, more preferably 80 mass%, based on the total mass of the monomer (a) and the monomer (b). % Or more. When it is within the above range, no abnormality in the coating film such as whitening, peeling or cracking occurs, and stable coating film solubility is maintained for a long period of time, thereby exhibiting an excellent antifouling effect. Specifically, this content is, for example, 60, 65, 70, 75, 80, 85, 90, 95, 100% by mass, and may be within a range between any two numerical values exemplified herein.

It is preferable that the weight average molecular weight of the copolymer of the present invention is 5000 to 300000. This is because if the molecular weight is less than 5000, the coating film of the antifouling paint becomes brittle, and peeling or cracking is liable to occur, and if it exceeds 300000, the viscosity of the copolymer solution increases and handling becomes difficult. Specifically, this Mw is, for example, 5000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000, 100000, 200000, 300000, and within the range between any two numerical values exemplified herein May be.

As the polymerization initiator, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, dimethyl-2,2'-azobisisobutyrate Azo compounds such as; Benzoyl peroxide, di-tert-butyl peroxide, tert-butylperoxybenzoate, tert-butylperoxyisopropylcarbonate, t-butylperoxy-2-ethylhexanoate, 1,1,3,3- Peroxides, such as tetramethylbutyl peroxy-2-ethylhexanoate, etc. are mentioned. These polymerization initiators can be used alone or in combination of two or more. Especially as the polymerization initiator, 2,2'-azobisisobutyronitrile and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate are preferable.

By appropriately setting the amount of the polymerization initiator used, the molecular weight of the triorganosilyl ester-containing copolymer can be adjusted.

As a polymerization method, solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc. are mentioned, for example. Among these, solution polymerization is preferable because the copolymer (A) can be synthesized particularly easily and with high precision.

In the above polymerization reaction, an organic solvent may be used as necessary. Examples of the organic solvent include aromatic hydrocarbon solvents such as xylene, ethylbenzene, and toluene; Aliphatic hydrocarbon solvents such as hexane and heptane; Ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate, and methoxypropyl acetate; Alcohol solvents such as isopropyl alcohol and butyl alcohol; Ether solvents such as dioxane, diethyl ether, and dibutyl ether; Ketone solvents, such as methyl ethyl ketone and methyl isobutyl ketone, etc. are mentioned. Among these, aromatic hydrocarbon solvents are particularly preferred, and xylene is more preferred. These solvents can be used alone or in combination of two or more.

The reaction temperature in the polymerization reaction may be appropriately set depending on the type of polymerization initiator, etc., and is usually about 70 to 120°C, preferably about 70 to 100°C. The reaction time in the polymerization reaction may be appropriately set depending on the reaction temperature and the like, and is usually about 4 to 8 hours.

The polymerization reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen gas or argon gas.

1-2. Antifouling agent (B)

Examples of the antifouling agent (B) include inorganic drugs and organic drugs.

Examples of the inorganic agent include copper oxide, copper thiocyanate (common name: copper rhodanide), and copper powder. Among these, copper oxide and copper rodan are particularly preferred, and copper oxide is more preferably surface-treated with glycerin, sucrose, stearic acid, lauric acid, lycithin, mineral oil or the like from the viewpoint of long-term stability during storage.

Examples of organic drugs include 2-mercaptopyridine-N-oxide copper (common name: copper pyrithione), 2-mercaptopyridine-N-oxide zinc (common name: zinc pyrithione), and zinc ethylene. Bisdithiocarbamate (common name: Zineb), 4,5-dichloro-2-n-octyl-3-isothiazolone (common name: Sea-Nine 211), 3,4- Dichlorophenyl-NN-dimethylurea (common name: diuron), 2-methylthio-4-t-butylamino-6-cyclopropylamino-s-triazine (common name: Irgarol 1051), 2-(p-chlorophenyl)-3-cyano-4-bromo-5-trifluoromethylpyrrole (common name: Econea 28), (±)-4-[1-(2,3-dimethylphenyl) ) Ethyl]-1H-imidazole (common name: medetomidine), and the like.

These antifouling agents can be used alone or in combination of two or more.

Although the content of the antifouling agent in the composition of the present invention is not particularly limited, it is usually 0.1 to 75% by mass, preferably 1 to 60% by mass, in the solid content of the composition of the present invention. When the content of the antifouling agent is less than 0.1% by mass, there is a fear that a sufficient antifouling effect cannot be obtained. When the content of the antifouling agent exceeds 75% by mass, the coating film to be formed is weak, and the adhesion to the object to be coated is also weak, and the function as an antifouling coating film cannot be sufficiently achieved.

1-3. Other additives

In addition, the resin for an antifouling paint of the present invention may be prepared as an antifouling paint by adding a dissolution regulator, a plasticizer, a pigment, a dye, an antifoaming agent, a dehydrating agent, a thixotropic agent, an organic solvent, and the like, if necessary.

Examples of dissolution modifiers include monocarboxylic acids such as rosin, rosin derivatives, naphthenic acid, cycloalkenylcarboxylic acid, bicycloalkenylcarboxylic acid, versatic acid, trimethylisobutenylcyclohexenecarboxylic acid, and metal salts thereof. Acids and salts thereof, or the aforementioned alicyclic hydrocarbon resins. These may be used alone or in combination of two or more.

Examples of the rosin derivative include hydrogenated rosin, disproportionated rosin, maleinized rosin, formylated rosin, polymerized rosin, and the like. As the alicyclic hydrocarbon resin, commercially available products include, for example, Quintone 1500, 1525L, 1700 (brand name, manufactured by Nippon Xeon Corporation).

As plasticizers, for example, phosphoric acid esters, phthalic acid esters, adipic acid esters, sebacic acid esters, epoxidized soybean oil, alkyl vinyl ether polymers, polyalkylene glycols, t-nonylpentasulfide, petrolatum, polybutene , Trimellitic acid tris (2-ethylhexyl), silicone oil, liquid paraffin, chlorinated paraffin, and the like. These can be used alone or in combination of two or more.

Examples of the dehydrating agent include synthetic zeolite adsorbents, orthoesters, silicates such as tetramethoxysilane and tetraethoxysilane, isocyanates, carbodiimides, and carbodiimidazoles. These can be used alone or in combination of two or more.

2. Method for producing antifouling coating composition

The antifouling coating composition of the present invention can be prepared, for example, by mixing and dispersing a mixed solution containing the above copolymer, antifouling agent, and other additives using a dispersing machine.

As the mixed liquid, it is preferable that various materials such as a copolymer and an antifouling agent are dissolved or dispersed in a solvent.

As said dispersing group, what can be used as a fine pulverizing group can be used suitably, for example. For example, a commercially available Dissolver, a homo mixer, a sand mill, a bead mill, or the like can be used. Moreover, you may mix and disperse the said mixed liquid using what added glass beads for mixing and dispersing etc. to a container equipped with a stirrer.

3. Antifouling treatment method, antifouling coating and coating

In the antifouling treatment method of the present invention, an antifouling coating film is formed on the surface of an object to be coated using the antifouling coating composition. According to the antifouling treatment method of the present invention, the antifouling coating film is gradually dissolved from the surface and the surface of the coating film is constantly renewed, so that adhesion of aquatic contaminant organisms can be prevented.

As a coating film formation, a ship (especially the bottom of a ship), fishing tools, underwater structures, etc. are mentioned, for example.

The thickness of the antifouling coating film may be appropriately set according to the type of the film formed, the sailing speed of the ship, and the sea water temperature. For example, when the film formation is the bottom of a ship, the thickness of the antifouling film is usually 50 to 700 μm, preferably 100 to 600 μm.

Example

Examples and the like are shown below to further clarify the features of the present invention. However, the present invention is not limited to these examples.

In each of Preparation Examples, Reference Examples, Examples, and Comparative Examples,% represents mass%.

The heating residue is a value obtained by heating at 125°C for 1 hour in accordance with JIS K 5601-1-2 (ISO 3251).

The weight average molecular weight (Mw) is a value (polystyrene conversion value) calculated|required by GPC.

The conditions of GPC are as follows.

Apparatus...HLC-8220GPC manufactured by Tosoh Corporation

Column...TSKgel SuperHZM-M (manufactured by Tosoh Corporation) 2 pieces

Flow...0.35 mL/min

Detector...RI

Column thermostat temperature...40°C

Eluent...THF

In addition, the unit of the blending amount of each component in the table is g.

<Production Example 1 (Production of Copolymer P-1)>

Into a 2000 ml flask equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel, 400 g of xylene was added, and the temperature was raised to 85 ± 2°C while stirring under a nitrogen atmosphere, and 175 g of triisopropylsilyl methacrylate, 2-methacrylic acid. A mixture of 300 g of oxyethyl, 25 g of methyl methacrylate, and 5 g of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (PEROCTA O manufactured by Nippon Yushi) was added to 85 ± 2°C. It was dripped for 1 hour while maintaining. After the dropwise addition, 0.5 g of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate was added 3 times every 1 hour while maintaining the temperature at 85 ± 2°C to complete the polymerization reaction, and then to 110°C. After heating up and holding for 30 minutes, it cooled, and 100 g of xylene was added and dissolved at 90 degreeC or less, and the copolymer solution P-1 was obtained. The heating residue of P-1 was 49.7%, and the weight average molecular weight was 52000.

<Production Examples 2 to 8, Reference Examples 1 to 12>

Polymerization was carried out in the same manner as in Preparation Example 1 using the organic solvents, monomers, and polymerization initiators shown in Tables 1 to 2, and copolymer solutions P-2 to P-8 and comparative copolymer solutions H-1 to H- I got 12. The heating residue and the weight average molecular weight of each obtained copolymer solution were measured. The results are shown in Tables 1 to 2.

<Examples 1 to 12, Comparative Examples 1 to 12>

Formulations shown in Tables 3 to 4 using the copolymer solutions P-1 to P-8 and comparative copolymer solutions H-1 to H-12 obtained in Preparation Examples 1 to 8 and Reference Examples 1 to 12 Prepared by

(How to adjust paint composition)

The antifouling coating compositions of Examples 1 to 12 and Comparative Examples 1 to 12 are small table-top sand mills for experiments (glass beads having a diameter of 1.5 to 2.5 mm) in a draft in which two humidifiers are operated and the humidity is maintained at 90% or more. After adjustment by mixing and dispersing for 1 hour using), it was divided into two 100 ml cans, the paint of one can was used for various tests of the coating film, and the paint of the other can was used for storage stability evaluation.

(Evaluation of storage stability of paint)

After measuring the viscosity of one of the paints placed in the canister, sealing, and storing for 3 months in a 45°C thermostat, the viscosity of the paint was measured with a B-type viscometer. The storage stability of the paint was evaluated by the following method.

◎: The viscosity change of the paint is less than 500mPa·s/25℃ (nearly not thickened)

○: The viscosity change of the paint is 500 ~ 5000mPa·s/25℃ (slightly thickened)

△: The viscosity change of the paint is 5000mPa·s/25℃ or more (thick thickened)

×: The viscosity is changed to the extent that it cannot be measured (gel or solidified)

The results are shown in Tables 3 and 4.

(Measurement of hardness of coating film)

The coating film hardness in the paint was measured with a pendulum hardness meter.

To measure the hardness of the coating film by a pendulum hardness tester, apply each paint sample to a glass plate (100 × 200 × 2 mm) so that the thickness after drying is about 100 μm, and after drying at 40° C. for 1 day, indoors at 25° C. Conducted in. The value is the number of counts. The results are shown in Tables 3 and 4.

(Rotary test)

A rotating drum with a diameter of 515 mm and a height of 440 mm was installed in the center of the water tank, and it could be rotated with a motor. In addition, a cooling device for maintaining a constant temperature of seawater and an automatic pH controller for maintaining a constant pH of seawater were installed.

The trial plate of the rotary test was produced according to the following method.

First, on a titanium plate (71 × 100 × 0.5 mm), a rust-preventing coating (epoxy vinyl-based A/C) was applied to a thickness of about 100 μm after drying and dried to form a rust-preventing coating. Thereafter, the coating compositions obtained in Examples 1 to 12 and Comparative Examples 1 to 12 were applied onto the rust-preventing coating film so that the thickness after drying was about 300 μm. The obtained coating was dried at 40° C. for 3 days to prepare a test plate having a dry coating film having a thickness of about 300 μm.

The prepared test plate was fixed to the rotating drum of the rotating device of the apparatus so as to contact seawater, and the rotating drum was rotated at a speed of 20 knots. In the meantime, the temperature of the seawater was maintained at 25°C and the pH was maintained at 8.0 to 8.2, and the seawater was changed every week.

·Measurement of dissolution amount of coating film

The amount of coating film dissolved per month by measuring the residual film thickness at the beginning of each test plate and every one month after the start of the test with a shape-measurement laser microscope VK-X100 manufactured by Keyence Corporation, and calculating the dissolved film thickness from the difference. (μm/month) was obtained.

The results are shown in Tables 3 and 4.

Observation of the surface condition of the coating film

When the residual film thickness was measured 6 months after the rotary test, the surface of each coating film was observed with the naked eye and a microscope to evaluate the surface condition of the coating film.

The evaluation of the surface state of the coating film was performed based on the following criteria.

◎: When there is no abnormality at all

○: Some hair cracks are visible

△: Hair cracks visible on the entire surface of the coating film

×: Cracks, blisters, or peeling or other abnormalities are observed in the coating film

The results are shown in Tables 3 and 4.

・Observation of whitening of the coating film

When the residual film thickness was measured 6 months after the rotary test, the presence or absence of whitening on the surface of each coating film was visually evaluated.

The evaluation of the presence or absence of whitening on the surface of the coating film with the naked eye was performed according to the following criteria.

○: When the color of the surface of the coating film hardly changes

△: When the color of the surface of the coating film is slightly whitened

X: When the color of the entire surface of the coating film is clearly whitened

The results are shown in Tables 3 and 4.

・Measurement of L value of coating film

The L value (brightness) was measured using a colorimeter for the coating film before the rotary test and the coating film remaining 6 months after the rotary test. As a colorimeter, a Color Meter ZE6000 manufactured by Nippon Denshoku Kogyo Co., Ltd. was used. As the L value (brightness), the value specified in JIS Z 8781-4 (calculation formula of the CIE method) was used. Since the L value (brightness) is 100 for white and 0 for black, when the surface of the coating film is whitened, the coating film becomes bright and the number of L values increases.

(Antifouling test (political immersion test))

Each of the antifouling paints obtained in Examples 1 to 12 and Comparative Examples 1 to 12 was applied on both sides of a hard vinyl chloride plate (100 × 200 × 2 mm) to a thickness of about 200 μm with a dry coating film. The test plate was immersed 1.5m below the sea level in Owase City, Mie Prefecture, and the test plate was observed and evaluated for 12 months for contamination by adherent organisms.

The evaluation was performed by visually observing the state of the coating film surface, and it was judged based on the following criteria.

◎: There is no adhesion of contaminated organisms such as shellfish and algae, and almost no slime.

○: There is no adhesion of contaminated organisms such as shellfish and algae, and the slime is adhered thinly (so that the coating surface is visible), but it can be removed by wiping lightly with a brush.

△: There is no adhesion of contaminated organisms such as shellfish and algae, but the slime is thickly attached to the extent that the coating surface is invisible, so that it does not fall off even when brushing with a brush.

×: Level to which fouling creatures such as shellfish and algae are attached

These results are shown in Tables 3 and 4.

Antifouling agents, pigments, and other additives in Tables 3 and 4 are specifically as follows.

<Antifouling agent>

Nitrous oxide (manufactured by Nissin Chemco, NC-301 average particle diameter 3μm)

Copper pyrithione (manufactured by Arch Chemicals, Copper omadine)

<Pigment>

Bengala (manufactured by Toda Pigment, TODA COLOR EP-13D)

Talc (manufactured by Matsumura Sangyo, Crown Talc 3S)

Zinc oxide (manufactured by Seido Chemical, two kinds of zinc oxide (brand name))

Titanium oxide (manufactured by Furugawaki Kaikinzoku, FR-41)

<Other additives>

Tetraethoxysilane (manufactured by Kishida Chemical, limited express reagent)

Rosin zinc salt (50% xylene solution)

Chlorinated paraffin (manufactured by Tosoh Corporation, brand name "Empala A-40S")

DISPARLON A603-20X (manufactured by Kusumoto Kasei, fatty acid amide thixotropic agent)

From Tables 3 and 4, the coatings prepared using the coating composition of the present invention (Examples 1 to 12) have good storage stability, and the formed coating film is maintained high in dissolution in seawater, and even in antifouling tests, shellfish or There is no adhesion of polluted organisms such as algae, and there is hardly any adhesion of slime. In addition, it can be seen that the state of the dried coating film after 6 months of the rotary test was also satisfactory without any abnormalities such as whitening, cracking, and peeling.

On the other hand, paints prepared using the paint compositions of Comparative Examples 1 to 6 or 10 to 12 have poor storage stability compared to the examples, and whitening is likely to occur in the coating film formed using this paint.

The paints prepared using the paint compositions of Comparative Examples 7 to 9 had low dissolution in seawater and insufficient prevention of adhesion of contaminants.

Claims (3)

As a copolymer for an antifouling coating composition obtained by copolymerizing a mixture of a monomer (a) and a polymerizable unsaturated monomer (b) other than the monomer (a),
The monomer (a) is represented by the following general formula (1),
The monomer (b) contains 2-methoxyethyl methacrylate,
The content of the monomer (a) accounts for 5 to 45% by mass of the total mass of the monomer (a) and the monomer (b),
The copolymer for an antifouling coating composition, wherein the content of 2-methoxyethyl methacrylate accounts for 55 to 95% by mass of the total mass of the monomer (a) and the monomer (b).
[Formula 1]

(In the formula, R ¹ is a methyl group, R ² , R ³ , R ⁴ are selected from a C 3 to C 8 branched alkyl group and a phenyl group, and may be the same or different) The method of claim 1,
The copolymer, wherein the total content of the monomer (a) and the 2-methoxyethyl methacrylate accounts for 70% by mass or more of the total mass of the monomer (a) and the monomer (b). As an antifouling coating composition comprising a copolymer and an antifouling agent,
The said copolymer is an antifouling coating composition which is the copolymer for antifouling coating compositions of Claim 1 or 2.