JPWO2019203154A1 - Copolymer for antifouling coating composition, antifouling coating composition containing the copolymer - Google Patents

Abstract

The present invention has good storage stability of the paint, and the obtained antifouling coating film is stable in seawater for a long period of time without any abnormality (whitening, peeling, cracks, etc.) of the coating film, stable coating film solubility and antifouling property. An object is to provide an antifouling coating composition that maintains its effect. According to the present invention, the copolymer (a) and the copolymerizable unsaturated monomer (b) other than the monomer (a) are obtained by copolymerization, and are obtained by copolymerization. In the combination, the monomer (a) is represented by the general formula (1), the monomer (b) contains 2-methoxyethyl methacrylate, and the monomer (a) is contained. 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 is the monomer (a) and the Provided is a copolymer for antifouling coating composition, which accounts for 55 to 95 mass% of the total mass of the monomer (b).

Description

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

  Aquatic fouling organisms such as barnacles, cerpra, blue mussels, hemlock worms, ascidians, sea squirrels, sea lions, slimes, etc. are used for underwater structures such as vessels (especially ship bottoms), fishing nets, fishing net accessories, and power plant water pipes. By adhering to the surface, there are problems that the functions of such ships and underwater structures are impaired, and the appearance is impaired. Particularly in the case of a ship, the resistance increases, the speed decreases and the fuel consumption increases, and the damage increases.

  Therefore, at present, antifouling paints using a triorganosilyl group-containing copolymer as a vehicle on the surface of underwater structures such as vessels (especially the bottom of boats), fishing nets, fishing net accessories, and power plant water pipes. Is widely used to form an antifouling coating film to prevent such damage.

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

  Examples of triorganosilyl group-containing copolymers include triorganosilyl ester-containing monomers composed of branched alkyl groups or aryl groups such as triisopropylsilyl ester and t-butyldiphenylsilyl ester, and (meth) acrylic acid 2- Triorganosilyl group-containing copolymers (Patent Documents 1 to 4) obtained by copolymerizing a (meth) acrylic acid alkoxyalkyl ester such as methoxyethyl have been proposed.

  However, since the antifouling paint using this triorganosilyl group-containing copolymer as a vehicle has poor storage stability, use a dehydrating agent such as ethyl silicate or anhydrite in the paint (Patent Document Although 5) to 6) have been proposed, they are not sufficient, and there is a problem that storage stability deteriorates when the humidity during the production of the coating is high.

  Further, these triorganosilyl group-containing copolymers have a problem that the initial coating film dissolution is not sufficient, and the coating film is whitened or fouling organisms are attached during the outfitting period or the initial berthing period. It was

JP, 7-102193, A JP 2001-226440 A JP, 2005-82725, A Japanese Patent Application No. 2016-062432 JP-A-7-18216 JP-A-9-48948

  The present invention has a good storage stability of the coating material, and the obtained antifouling coating film has stable coating film solubility and antifouling for a long period of time in seawater without abnormalities (whitening, peeling, cracks, etc.) of the coating film. An object of the present invention is to provide an antifouling coating composition that maintains its effect.

According to the present invention, the copolymer (a) and the polymerizable unsaturated monomer (b) other than the monomer (a) are obtained by copolymerization, and the copolymer is used for the antifouling coating composition. Being a coalition,
The monomer (a) is represented by the general formula (1),
The monomer (b) contains 2-methoxyethyl methacrylate,
The content of the monomer (a) accounts for 5 to 45 mass% of the total mass of the monomer (a) and the monomer (b),
Provided is a copolymer for an antifouling coating composition, wherein the content of 2-methoxyethyl methacrylate accounts for 55 to 95 mass% of the total mass of the monomer (a) and the monomer (b). To be done.

  As a result of earnest studies, the present inventor has found that a copolymer (A) obtained by containing a specific amount of 2-methoxyethyl methacrylate in a monomer (b) to be copolymerized with a monomer (a) having a specific structure. ) Is used as the vehicle, the storage stability of the paint is very good even when it is manufactured in a high humidity condition, and the coating film remains in seawater for a long period of time without any abnormalities such as whitening, peeling and cracks. The inventors have found that an antifouling coating composition that maintains stable coating film solubility and antifouling effect can be obtained, and arrived at the present invention.

Hereinafter, the present invention will be described in detail.
1. Antifouling paint composition The antifouling paint composition of the present invention contains a copolymer (A) for an antifouling paint composition and an antifouling agent (B).

1-1. Copolymer (A) for antifouling coating composition
The antifouling coating composition copolymer (A) is a triorganosilyl group-containing copolymer and is obtained by copolymerizing a mixture of the monomer (a) and the monomer (b). The copolymer (A) contains monomer units derived from the monomers (a) and (b).

<Monomer (a)>
The monomer (a) is a methacrylic acid triorganosilyl ester monomer and is represented by the general formula (1).
(In the formula, R ¹ is a methyl group, R ² , R ³ , and R ⁴ are selected from a branched alkyl group having 3 to 8 carbon atoms and a phenyl group, and may be the same or different.)

  In the present invention, examples of the monomer (a) represented by the general formula (1) include triisopropylsilyl methacrylate, triisobutylsilyl methacrylate, tris-butylsilyl methacrylate, triisoamylsilyl methacrylate, and methacrylic acid. Tris (2-ethylhexyl) silyl acid, triphenylsilyl methacrylate, diisopropylisobutylsilyl methacrylate, diisopropylisoamylsilyl methacrylate, diisopropyl (2-ethylhexyl) silyl methacrylate, diisopropylphenylsilyl methacrylate, diisopropylcyclohexylsilyl methacrylate, methacrylic acid Acid t-butyl diisopropyl silyl methacrylate, t-butyl diisobutyl silyl methacrylate, t-butyl diisoamyl silyl methacrylate, t-butyl methacrylate Le butyldiphenylsilyl, and the like, preferably, methacrylic acid t- butyldiphenylsilyl and methacrylic acid triisopropylsilyl, particularly preferably methacrylic acid triisopropylsilyl. These monomers are used alone or in combination of two or more.

<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 essential that the monomer (b) contains 2-methoxyethyl methacrylate, and the monomer (b) can be obtained by containing 2-methoxyethyl methacrylate in a specific amount. The coating composition has a very good storage stability, and the coating film is free from abnormalities such as whitening, peeling and cracks for a long period of time, and has a stable coating solubility and antifouling effect. To be effective.

  The monomer (b) may contain only 2-methoxyethyl methacrylate, or may contain a monomer other than 2-methoxyethyl methacrylate. Examples of monomers other than 2-methoxyethyl methacrylate include the following.

-Triisopropylsilyl acrylate, triisobutylsilyl acrylate, tris-butylsilyl acrylate, triisoamylsilyl acrylate, tris (2-ethylhexyl) silyl acrylate, triphenylsilyl acrylate, diisopropylisobutylsilyl acrylate, acrylic acid Diisopropylisoamylsilyl, diisopropyl (2-ethylhexyl) silyl acrylate, diisopropylphenylsilyl acrylate, diisopropylcyclohexyl acrylate, t-butyldiisopropylsilyl acrylate, t-butyldiisobutylsilyl acrylate, t-butyldiisoamylsilyl acrylate And acrylic acid triorganosilyl esters such as t-butyldiphenylsilyl acrylate.

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

Zinc (meth) acrylate versatate, magnesium (meth) acrylate versatate, copper (meth) acrylate versatate, zinc (meth) acrylate octylate, magnesium (meth) acrylate octylate, copper (meth) acrylate octylate, laurin Zinc acid (meth) acrylate, magnesium laurate (meth) acrylate, copper laurate (meth) acrylate, zinc stearate (meth) acrylate, magnesium stearate (meth) acrylate, copper stearate (meth) acrylate and the like (meth ) Metal acrylates such as metal acrylate pendants, zinc (meth) acrylate, and copper (meth) acrylate.

-A vinyl compound having a functional group 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, vinyltoluene and α-methylstyrene.

-Dialkyl ester compounds of unsaturated dibasic acids such as dimethylmalate, dibutylmalate and dimethylfumarate.

  Other copolymerizable monomers other than 2-methoxyethyl methacrylate are used alone or in combination of two or more, preferably (meth) acrylic acid esters, particularly preferably (meth) acrylic acid methyl ester. Is.

  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. Is, for example, 0.75, 0.8, 0.85, 0.9, 0.95, and may be within a range between any two of the numerical values exemplified here.

<Synthesis of Copolymer (A)>
The copolymer (A) used in the antifouling paint of the present invention can be obtained by copolymerizing a mixture of the monomer (a) and the monomer (b). The copolymerization is performed in the presence of a polymerization initiator, for example.

  The content of the monomer (a) in the mixture is 5 to 45% by mass, preferably 10 to 40% by mass, more preferably 15 to 35% by mass. When the content of the monomer (a) is 5 to 45% by mass, the resulting antifouling coating composition has very good paint stability, and the coating film is whitened, peeled, and cracked in seawater for a long period of time. It is possible to maintain stable coating film solubility and antifouling performance from the beginning without causing such abnormalities. This content is specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45% by mass, and falls within a range between any two of the numerical values exemplified here. Good.

  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 solubility and antifouling effect in seawater from the beginning. Thus, the coating film abnormality such as whitening, peeling and cracking does not occur, and the stable coating film solubility and antifouling effect can be maintained for a long period of time. Specifically, this content is, for example, 55, 60, 65, 70, 75, 80, 85, 90, 95% by mass, and falls within a range between any two of the numerical values exemplified here. Good.

  The total content of the monomer (a) and 2-methoxyethyl methacrylate is 60% by mass or more, and preferably 70% by mass, of the total mass of the monomer (a) and the monomer (b). Or more, More preferably, it is 80 mass% or more. Within the above range, no abnormalities in the coating film such as whitening, peeling and cracking will occur, and stable coating film solubility will be maintained for a long time and an excellent antifouling effect will be exhibited. Specifically, this content is, for example, 60, 65, 70, 75, 80, 85, 90, 95, 100% by mass, and falls within a range between any two of the numerical values exemplified here. Good.

  The weight average molecular weight of the copolymer of the present invention is preferably 5,000 to 300,000. When the molecular weight is less than 5,000, the coating film of the antifouling paint becomes fragile and easily peels off or cracks, and when it exceeds 300,000, the viscosity of the copolymer solution increases and the handling becomes difficult. . Specifically, this Mw is, for example, 5000, 10000, 20000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 200,000, 300,000, and is between any two of the numerical values exemplified here. It may be within the range.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis-2-methylbutyronitrile, dimethyl-2,2′-azobisisobutyrate. Azo compounds such as benzoyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, t-butyl peroxy-2-ethylhexanoate, 1,1,3 , 3-tetramethylbutylperoxy-2-ethylhexanoate and the like. These polymerization initiators may be used alone or in combination of two or more. As the polymerization initiator, 2,2′-azobisisobutyronitrile and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate are particularly preferable.

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

  Examples of the polymerization method include solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization and the like. Of these, solution polymerization is particularly preferable because the copolymer (A) can be synthesized simply and accurately.

  In the polymerization reaction, an organic solvent may be used if 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, methoxypropyl acetate. Alcoholic solvents such as isopropyl alcohol and butyl alcohol. Ether-based solvents such as dioxane, diethyl ether, dibutyl ether. Examples include ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone. Among these, aromatic hydrocarbon solvents are particularly preferable, and xylene is more preferable. These solvents may 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 the polymerization initiator and the like, 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 according to the reaction temperature and the like, and is usually about 4 to 8 hours.

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

1-2. Antifouling agent (B)
Examples of the antifouling agent (B) include inorganic agents and organic agents.
Examples of the inorganic agent include cuprous oxide, copper thiocyanate (general name: copper rhodanide), and copper powder. Among these, in particular, cuprous oxide and rhodan copper are preferred, and cuprous oxide having a surface treated with glycerin, sucrose, stearic acid, lauric acid, lysine, mineral oil, etc. has a long-term stability during storage. Is more preferable.

Examples of the organic drug include 2-mercaptopyridine-N-oxide copper (generic name: copperpyrithione), 2-mercaptopyridine-N-oxide zinc (generic name: zinc pyrithione), zinc ethylenebisdithiocarbamate (generic name: zineb). ), 4,5-Dichloro-2-n-octyl-3-isothiazolone (generic name: Sinaine 211), 3,4-dichlorophenyl-NN-dimethylurea (generic name: diuron), 2-methylthio-4-. t-butylamino-6-cyclopropylamino-s-triazine (generic name: Irgalol 1051), 2- (p-chlorophenyl) -3-cyano-4-bromo-5-trifluoromethylpyrrole (generic name: Econea 28), (±) -4- [1- (2,3-Dimethylphenyl) ethyl] -1H-imidazole Generic name: medetomidine), and the like.
These antifouling agents can be used alone or in combination of two or more.
The content of the antifouling agent in the composition of the present invention is not particularly limited, but 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, a sufficient antifouling effect may not be obtained. When the content of the antifouling agent is more than 75% by mass, the coating film formed is fragile, and further, the adhesiveness to the material to be coated is weak, so that the function as the antifouling coating film cannot be sufficiently fulfilled.

1-3. Other additives Further, the resin for antifouling paint of the present invention may be added with an elution regulator, a plasticizer, a pigment, a dye, a defoaming agent, a dehydrating agent, a thixotropic agent, an organic solvent or the like as necessary to prevent the resin. Examples of dissolution modifiers that can be used as stain paints include rosin, rosin derivatives, naphthenic acid, cycloalkenylcarboxylic acid, bicycloalkenylcarboxylic acid, versatic acid, trimethylisobutenylcyclohexenecarboxylic acid, and metal salts thereof. , Monocarboxylic acid and salts thereof, or the alicyclic hydrocarbon resin. These can be used alone or in combination of two or more.
Examples of the rosin derivative include hydrogenated rosin, disproportionated rosin, maleated rosin, formylated rosin, and polymerized rosin. Examples of the alicyclic hydrocarbon resin include commercially available products such as Quinton 1500, 1525L, 1700 (trade name, manufactured by Nippon Zeon Co., Ltd.).
Examples of the plasticizer include phosphoric acid ester, phthalic acid ester, adipic acid ester, sebacic acid ester, epoxidized soybean oil, alkyl vinyl ether polymer, polyalkylene glycols, t-nonyl pentasulfide, petrolatum, polybutene. , Tris (2-ethylhexyl) trimellitate, 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, carbodiimidazoles and the like. 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 comprises, for example, mixing and dispersing a mixed solution containing the copolymer, the antifouling agent and other additives using a disperser. Can be manufactured by
The mixed solution is preferably a solution in which various materials such as a copolymer and an antifouling agent are dissolved or dispersed in a solvent.
As the disperser, for example, one that can be used as a fine pulverizer can be preferably used. For example, a commercially available dissolver, homomixer, sand mill, bead mill and the like can be used. Further, the mixed liquid may be mixed and dispersed by using a container equipped with a stirrer to which glass beads for mixing and dispersing are added.

3. Antifouling Treatment Method, Antifouling Coating Film, and Painted Material The antifouling treatment method of the present invention forms an antifouling coating film on the surface of a film-forming target using the above 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 coating film surface is constantly renewed, so that adhesion of aquatic fouling organisms can be prevented.
Examples of the film forming object include ships (especially ship bottoms), fishing gear, underwater structures and the like.
The thickness of the antifouling coating film may be appropriately set according to the type of the film-forming material, the navigation speed of the ship, the seawater temperature, and the like. For example, when the material to be coated is the bottom of a ship, the thickness of the antifouling coating is usually 50 to 700 μm, preferably 100 to 600 μm.

The features of the present invention will be further clarified by showing Examples and the like below. However, the present invention is not limited to these examples.
In the production examples, reference examples, examples and comparative examples,% means mass%.
The heating residue is a value obtained by heating at 125 ° C. for 1 hour based on JIS K 5601-1-2 (ISO 3251).

The weight average molecular weight (Mw) is a value (polystyrene conversion value) obtained by GPC.
The conditions of GPC are as follows.
Device: Tosoh Corporation HLC-8220GPC
Column: TSKgel Super HZM-M (manufactured by Tosoh Corporation) 2 Flow rate: 0.35 mL / min
Detector ・ ・ ・ RI
Column temperature chamber temperature ... 40 ℃
Eluent ... THF

  The unit of the blending amount of each component in the table is g.

<Production Example 1 (Production of Copolymer P-1)>
A 2000 ml flask equipped with a thermometer, a reflux condenser, a stirrer and a dropping funnel was charged with 400 g of xylene and heated to 85 ± 2 ° C. under stirring under a nitrogen atmosphere to give 175 g of triisopropylsilyl methacrylate and 2 parts of methacrylic acid. -While keeping a mixed solution of 300 g of methoxyethyl, 25 g of methyl methacrylate, 5 g of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (Perocta O manufactured by NOF CORPORATION) at 85 ± 2 ° C, Dropped over time. After the dropping, 0.5 g of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate was added 3 times every hour while maintaining the temperature at 85 ± 2 ° C., and the polymerization reaction was completed at 110 ° C. The temperature was raised to 30 ° C., the mixture was kept for 30 minutes, then cooled, and 100 g of xylene was added and dissolved at 90 ° C. or lower to obtain a copolymer solution P-1. The heating residue of P-1 was 49.7%, and the weight average molecular weight was 52,000.

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

<Examples 1 to 12, Comparative Examples 1 to 12>
Using the copolymer solutions P-1 to P-8 and the comparative copolymer solutions H-1 to H-12 obtained in Production Examples 1 to 8 and Reference Examples 1 to 12, antifouling coating compositions are shown in Table 3. ~ Prepared according to the formulation shown in Table 4.

(Method for preparing coating composition)
The antifouling coating compositions of Examples 1 to 12 and Comparative Examples 1 to 12 were used as small experimental tabletop sand mills (diameter 1. After adjusting by mixing and dispersing for 1 hour using glass beads of 5 to 2.5 mm, divide into two 100 ml tin cans, the paint of one tin can is used for various tests of coating film. The other tin can paint was used for storage stability evaluation.

(Evaluation of paint storage stability)
After measuring the viscosity of one of the paints placed in the tin can, it was sealed and stored in a thermostat at 45 ° C for 3 months, and then the viscosity of the paint was measured with a B-type viscometer.
The storage stability of the paint was evaluated by the following method.
⊚: Change in viscosity of paint is less than 500 mPa · s / 25 ° C. (those that did not thicken)
◯: Viscosity change of paint is 500 to 5000 mPa · s / 25 ° C (thickened slightly)
Δ: Change in paint viscosity of 5000 mPa · s / 25 ° C. or more (thickened significantly)
×: Viscosity changed to unmeasurable (gel-like or solidified)
The results are shown in Tables 3 and 4.

(Measurement of hardness of coating film)
The coating film hardness of the paint was measured with a pendulum hardness meter.
The coating film hardness is measured with a pendulum hardness meter by coating each paint sample on a glass plate (100 × 200 × 2 mm) so that the thickness after drying is about 100 μm, and drying at 40 ° C. for 1 day, then at 25 ° C. in a room. I went there. The value is a count number.
The results are shown in Tables 3 and 4.

(Rotary test)
A rotating drum having a diameter of 515 mm and a height of 440 mm was attached to the center of the water tank so that it could be rotated by a motor. Further, a cooling device for keeping the temperature of seawater constant and a pH automatic controller for keeping the pH of seawater constant were attached.
The test plate for the rotary test was prepared according to the following method.
First, a rust preventive coating film is formed by applying a rust preventive coating (epoxy vinyl A / C) on a titanium plate (71 × 100 × 0.5 mm) so that the thickness after drying is about 100 μm and drying. did. Then, the coating compositions obtained in Examples 1 to 12 and Comparative Examples 1 to 12 were applied on the rust-preventive coating film so that the thickness after drying was about 300 μm. The obtained coated product was dried at 40 ° C. for 3 days to prepare a test plate having a dry coating film with a thickness of about 300 μm.
The prepared test plate was fixed to the rotating drum of the rotating device of the above device so as to come into contact with seawater, and the rotating drum was rotated at a speed of 20 knots. During that time, the temperature of seawater was maintained at 25 ° C. and the pH was maintained at 8.0 to 8.2, and the seawater was replaced every week.

-Measurement of the amount of coating film dissolved The initial thickness of each test plate and the remaining film thickness after the start of the test were measured with a shape measurement laser microscope VK-X100 manufactured by Keyence Co., Ltd., and the film thickness dissolved from the difference. The amount of dissolved coating film (μm / month) per month was obtained by calculating
The results are shown in Tables 3 and 4.

-Observation of surface state of coating film When measuring the remaining film thickness after 6 months of the rotary test, the surface state of the coating film was evaluated by observing the surface of each coating film with the naked eye and a microscope.
The surface condition of the coating film was evaluated according to the following criteria.
⊚: No abnormality at all ○: Slight hair cracks are seen Δ: Hair cracks are seen on the entire surface of the coating film ×: Abnormalities in the coating film such as cracks, blister or peeling are seen Table 3 shows the results. , Shown in Table 4.

・ Observation of whitening of coating film When measuring the remaining film thickness after 6 months of the rotary test, the presence or absence of whitening of each coating film surface was visually evaluated. The following criteria were used to evaluate the presence or absence of whitening of the coating film surface visually. It was
◯: When the color of the coating film surface hardly changed Δ: When the color of the coating film surface was slightly whitened ×: When the color of the entire coating film was clearly whitened The results are shown in Table 3 and Table 3. 4 shows.

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

(Antifouling test (stationary 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 PVC plate (100 x 200 x 2 mm) as a dry coating film to a thickness of about 200 microns. The test plate was immersed in 1.5 m below the sea surface in Owase City, Mie Prefecture, and the stain on the test plate due to attached organisms was observed and evaluated for 12 months.
The evaluation was performed by visually observing the state of the coating film surface, and judged according to the following criteria.
⊚: No attachment of fouling organisms such as shellfish and algae, and almost no slime.
◯: A level where there is no attachment of fouling organisms such as shellfish and algae and the slime is attached thinly (to the extent that the coating surface can be seen), but can be wiped lightly with a brush.
Δ: Staining organisms such as shellfish and algae are not attached, but the slime is attached so thick that the coating film surface cannot be seen, and it is a level that cannot be removed even by wiping with a brush.
×: A level where fouling organisms such as shellfish and algae are attached.
The results are shown in Tables 3 and 4.

Details of the antifouling agents, pigments and other additives in Tables 3 and 4 are as follows.
<Antifouling agent>
Cuprous oxide (Nisshin Chemco, NC-301 average particle size 3 μm)
Copper Pyrithione (Arch Chemicals, Copper Omagine)
<Pigment>
Bengal (TODA COLOR EP-13D, manufactured by Toda Pigment)
Talc (Matsumura Sangyo, Crown Talc 3S)
Zinc oxide (Shodo Chemical, 2 types of zinc oxide (trade name))
Titanium oxide (Furukawa Kikai Metal, FR-41)
<Other additives>
Tetraethoxysilane (Kishida Chemical, special grade reagent)
Rosin zinc salt (50% xylene solution)
Chlorinated paraffin (Tosoh Corporation, trade name "Empala A-40S")
Disparlon A603-20x (Kusumoto Kasei, fatty acid amide thixotropic agent)

From Tables 3 and 4, the paints produced using the paint compositions of the present invention (Examples 1 to 12) have good storage stability, and the formed coating films have a solubility in seawater. It is maintained at a high level, and even in antifouling tests, there is no attachment of fouling organisms such as shellfish and algae, and almost no attachment of slime. Further, it can be seen that the state of the dried coating film after 6 months of the rotary test is good without any abnormalities such as whitening, cracks and peeling.
On the other hand, the paints produced using the paint compositions of Comparative Examples 1 to 6 or 10 to 12 are not as good in storage stability as compared with the Examples, and the coating film formed using this paint is Whitening was likely to occur.
The paints produced using the paint compositions of Comparative Examples 7 to 9 had a low amount of dissolution in seawater and were insufficient in preventing the attachment of fouling organisms.

Claims (3)

A copolymer for an antifouling coating composition, which is 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 general formula (1),
The monomer (b) contains 2-methoxyethyl methacrylate,
The content of the monomer (a) accounts for 5 to 45 mass% of the total mass of the monomer (a) and the monomer (b),
The copolymer for 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).
(In the formula, R ¹ is a methyl group, R ² , R ³ , and R ⁴ are selected from a branched alkyl group having 3 to 8 carbon atoms and a phenyl group, and may be the same or different.)   The total content of the monomer (a) and 2-methoxyethyl methacrylate accounts for 70% by mass or more of the total mass of the monomer (a) and the monomer (b). The copolymer described. An antifouling coating composition comprising a copolymer and an antifouling agent,
An antifouling coating composition, wherein the copolymer is the copolymer for an antifouling coating composition according to claim 1 or 2.