Antifouling coating composition

Abstract

To provide an antifouling coating composition capable of forming a coating film that combines bioresistance and contamination resistance without relying on photocatalytic semiconductor materials.SOLUTION: There is provided an antifouling coating composition containing resin (A) having a weight-average molecular weight of 10,000 or more and 200,000 or less, which comprises units derived from monomer (a1), units derived from monomer (a2), and units derived from monomer (a3). The monomer (a1) is one or more selected from the group consisting of alkyl acrylate and alkyl methacrylate, the monomer (a2) is an ethylene-unsaturated monomer having one or more hydrophilic functional groups, and the monomer (a3) is a monomer having one or more alkoxysilyl groups.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an antifouling coating composition. [Background technology]

[0002] The surfaces of outdoor buildings and structures become contaminated by oily dirt and dust from vehicle exhaust fumes, etc. This contamination mars the aesthetics of the buildings and structures and significantly reduces their value. One method for improving the antifouling properties of a painted surface is to make the paint hydrophilic, so that contaminants adhering to the surface of the painted film can be self-cleaned by rain.

[0003] However, although the method of making the paint hydrophilic can suppress contamination by oily stains, dirt, dust, and the like, the hydrophilic nature of the paint makes it susceptible to contamination by algae, mold, and the like. In contrast, forming a coating film containing a photocatalytic semiconductor material, as in Patent Document 1, not only makes the surface superhydrophilic and antifouling, but also makes it possible to suppress the growth of algae, mold, and the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-086170 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as in Patent Document 1, when a photocatalytic semiconductor material is contained in a coating film, the colorant is easily faded or decolorized by light. Therefore, there is a problem that it is difficult to use a colorant with low photostability, and there is a limit to the colorants that can be used. In particular, the inventors have confirmed that when a decolorizable colorant is coexisted with the photocatalytic semiconductor material, the color of the decolorizable colorant disappears in a very short time.

[0006] It is known that decolorizable colorants can be used as markers to indicate painted areas. That is, by blending decolorizable colorants into transparent paint, painted and unpainted areas can be easily distinguished visually. Furthermore, after the painting work is completed, the decolorizable colorants lose their color over time, so they do not conceal the color of the base material before the transparent paint is applied. However, if the color of the decolorizing colorant fades too quickly, it becomes impossible to visually distinguish between painted and unpainted areas before the painting job is completed.

[0007] Therefore, the present inventors investigated various methods to develop a versatile antifouling coating composition that can form a coating film that is resistant to fouling by algae, mold, and the like (hereinafter also referred to as "biological resistance") and that is resistant to fouling by oily dirt from automobile exhaust fumes and the like, dirt, and the like (hereinafter also referred to as "fouling resistance"), without relying on a photocatalytic semiconductor material.

[0008] The present inventors attempted to create an antifouling coating composition that would provide a coating film that is hydrophilic yet has excellent organism resistance by incorporating a larger amount of antifungal agent and antialgae agent than usual. However, when a large amount of anti-mold and anti-algae agents was added, although the organism resistance improved initially, it deteriorated over time. This is thought to be because the molecular weight of the anti-mold and anti-algae agents is low, so they bleed out of the coating film over time and are eventually lost from the coating film. In view of the above circumstances, an object of the present invention is to provide an antifouling coating composition that can form a coating film that is both biologically resistant and stain-resistant without relying on a photocatalytic semiconductor material. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention employs the following configuration. [1] An antifouling coating composition containing a resin (A) that contains units derived from a monomer (a1), units derived from a monomer (a2), and units derived from a monomer (a3), and that has a weight-average molecular weight of 10,000 or more and 200,000 or less, the monomer (a1) is at least one selected from the group consisting of alkyl acrylates and alkyl methacrylates, the monomer (a2) is an ethylenically unsaturated monomer having one or more hydrophilic functional groups, the monomer (a3) ​​is a monomer having one or more alkoxysilyl groups, the proportion of units derived from the monomer (a1) in the total mass of all units constituting the resin (A) is 4.9 to 30 mass%, the proportion of units derived from the monomer (a2) in the total mass of all units constituting the resin (A) is 55 to 95 mass%, An antifouling coating composition, wherein the proportion of units derived from the monomer (a3) ​​in the total mass of all units constituting the resin (A) is 0.1 to 15 mass %. [2] The antifouling coating composition according to [1], further containing colloidal silica. [3] The antifouling coating composition according to [1] or [2], further comprising a monomer (a4) in addition to the resin (A), the monomer (a4) being a monomer having one or more alkoxysilyl groups. [4] The antifouling coating composition according to any one of [1] to [3], further comprising a decolorizable colorant in addition to the resin (A), and substantially not containing a photocatalytic semiconductor material. [Effects of the Invention]

[0010] According to the antifouling coating composition of the present invention, a coating film having both biological resistance and fouling resistance can be formed without relying on a photocatalytic semiconductor material. DETAILED DESCRIPTION OF THE INVENTION

[0011] In this specification and claims, the use of "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. The "unit" constituting the resin means an atomic group formed directly by polymerization of a monomer. "Substantially free" means that it is not intentionally blended, and either contains only unavoidable contaminants or is completely free.

[0012] "(Meth)acryl" in the compound name means either or both of "acryl" and "methacryl." For example, "(meth)acrylamide" means either or both of "acrylamide" and "(methacrylamide). The term "(meth)acrylate" in a compound name means either or both of "acrylate" and "methacrylate." For example, "dimethylaminoethyl (meth)acrylate" means either or both of "dimethylaminoethyl acrylate" and "dimethylaminoethyl methacrylate."

[0013] The antifouling coating composition of the present embodiment (hereinafter also referred to as "the composition") contains the resin (A) shown below. The present composition preferably further contains colloidal silica in addition to the resin (A). In addition to the resin (A), the present composition preferably further contains a monomer (a4) having one or more alkoxysilyl groups.

[0014] The present composition may further contain components other than the resin (A), colloidal silica, and monomer (a4) (hereinafter also referred to as "optional components"), as long as the effects of the present invention are not impaired. When the present composition contains a decolorizable colorant, it is preferable that the composition contains substantially no photocatalytic semiconductor material.

[0015] <Resin (A)> The resin (A) in the present composition contains units derived from the following monomer (a1), units derived from the monomer (a2), and units derived from the monomer (a3). The monomer (a1), the monomer (a2) and the monomer (a3) ​​are different from each other. The resin (A) may further contain units derived from monomers other than the monomers (a1), (a2) and (a3) ​​(hereinafter also referred to as "other monomers"), if necessary, within a range that does not impair the effects of the present invention.

[0016] Monomer (a1): one or more monomers selected from the group consisting of alkyl acrylates and alkyl methacrylates. Monomer (a2): An ethylenically unsaturated monomer having one or more hydrophilic functional groups. Monomer (a3): A monomer having one or more alkoxysilyl groups.

[0017] [Monomer (a1)] The monomer (a1) is at least one selected from the group consisting of alkyl acrylates and alkyl methacrylates. The monomer (a1) does not have a functional group such as a hydrophilic functional group or an alkoxysilyl group.

[0018] Examples of alkyl acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, and cyclohexyl acrylate.

[0019] Examples of alkyl methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, and cyclohexyl methacrylate. The monomer (a1) may be one selected from the group consisting of alkyl acrylates and alkyl methacrylates, or two or more selected from the group consisting of alkyl acrylates and alkyl methacrylates.

[0020] Among these, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, isobutyl methacrylate, and t-butyl methacrylate are preferred because they do not impair the hydrophilicity of the resin (A) and also because they provide good durability of the stain resistance.

[0021] [Monomer (a2)] The monomer (a2) is an ethylenically unsaturated monomer having one or more hydrophilic functional groups. The hydrophilic functional group is preferably at least one selected from the group consisting of an amino group, an amide group, a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphate group, a quaternary ammonium group, a sulfate group, a morpholino group, and a poly(oxyalkylene) group.

[0022] Examples of the amino group include a primary amino group, a secondary amino group, and a tertiary amino group, and -NR 1 R 2 (where R 1 and R 2 each independently represents a hydrogen atom or an alkyl group. The ethylenically unsaturated monomer having an amino group may be any monomer having an amino group, and examples thereof include dimethylaminoethyl (meth)acrylate, diethylaminomethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate.

[0023] Examples of the ethylenically unsaturated monomer having an amide group include (meth)acrylamide, Nt-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, and N-isopropyl(meth)acrylamide.

[0024] Examples of ethylenically unsaturated monomers having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 10-hydroxydodecyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and [4-(hydroxymethyl)cyclohexyl]methyl acrylate.

[0025] Examples of the ethylenically unsaturated monomer having a carboxy group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, carboxyethyl acrylate, and carboxypentyl acrylate. Examples of the ethylenically unsaturated monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, styrene sulfonic acid, ethyl (meth)acrylic acid-2-sulfonate, and allyl sulfonic acid.

[0026] Examples of the ethylenically unsaturated monomer having a phosphoric acid group include 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxyethyl acid phosphate, and dibutyl-2-acryloyloxyethyl phosphate. Examples of the ethylenically unsaturated monomer having a morpholino group include 4-acryloylmorpholine.

[0027] Examples of ethylenically unsaturated monomers having a hydrophilic functional group other than those listed above include N-hydroxyethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, 2-acrylamido-2-methylpropanesulfonic acid diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, (2-hydroxyethyl)methacrylate acid phosphate N,N-dimethylaminoethyl(meth)acrylate methyl chloride salt, N,N-dimethylaminopropyl(meth)acrylamidomethyl chloride salt, and N,N-dimethylaminoethyl(meth)acrylate benzyl chloride salt.

[0028] These may be used alone or in combination of two or more. Among these, acrylic acid, methacrylic acid, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate are preferred because they provide good stain resistance.

[0029] [Monomer (a3)] The monomer (a3) ​​is a monomer having one or more alkoxysilyl groups. Specific examples of the monomer (a3) ​​include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0030] These may be used alone or in combination of two or more. Among these, those having a vinyl group, an acryloyl group, or a methacryloyl group are preferred because they provide good stain resistance and improve the durability of stain resistance. Specific examples include vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane.

[0031] [Other monomers] The other monomers than the monomer (a1), the monomer (a2), and the monomer (a3) ​​are not particularly limited as long as they are copolymerizable with the monomer (a1), the monomer (a2), and the monomer (a3).

[0032] [Content] The content of units derived from monomer (a1) relative to the total mass of all units constituting resin (A) is preferably 4.9 mass% or more, more preferably 7.5 mass% or more, and is preferably 30 mass% or less, more preferably 25 mass% or less, relative to the total mass of all units constituting resin (A). When the content of the monomer (a1) is equal to or greater than the lower limit, the durability of the stain resistance of the coating film is improved. When the content of the monomer (a1) is equal to or less than the upper limit, the stain resistance of the coating film is good.

[0033] The content of units derived from monomer (a2) relative to the total mass of all units constituting resin (A) is preferably 55 mass% or more, more preferably 65 mass% or more, and is preferably 95 mass% or less, more preferably 92 mass% or less, relative to the total mass of all units constituting resin (A). When the content of units derived from monomer (a2) is equal to or greater than the lower limit, the hydrophilic effect is sufficiently exhibited and the stain resistance of the coating film is improved.When the content of units derived from monomer (a2) is equal to or less than the upper limit, the durability of the stain resistance is improved.

[0034] The content of units derived from monomer (a3) ​​relative to the total mass of all units constituting resin (A) is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and is preferably 15 mass% or less, more preferably 12 mass% or less, relative to the total mass of all units constituting resin (A). When the content of units derived from monomer (a3) ​​is equal to or greater than the lower limit, the durability of the stain resistance of the coating film is good. When the content of units derived from monomer (a3) ​​is equal to or less than the upper limit, the storage stability is good.

[0035] The content of units derived from monomers other than the monomers (a1), (a2) and (a3) ​​relative to the total mass of all units constituting the resin (A) is preferably 10 mass% or less, more preferably 8 mass% or less. When the content of units derived from monomers other than the monomer (a1), the monomer (a2) and the monomer (a3) ​​is equal to or less than the upper limit, the hydrophilizing effect is sufficiently exhibited, and the stain resistance of the coating film becomes good.

[0036] [Physical properties of resin (A)] The weight average molecular weight (Mw) of the resin (A) is 10,000 or more, and more preferably 50,000 or more, and 200,000 or less, and more preferably 150,000 or less.

[0037] When the weight-average molecular weight (Mw) of the resin (A) is equal to or greater than the lower limit, the durability of the stain resistance is good. When the weight-average molecular weight is equal to or less than the upper limit, the surface layer gradually washes away with rain, resulting in good biological resistance. In addition, when producing the resin (A), excessive viscosity that makes synthesis difficult can be avoided. The weight average molecular weight of the resin (A) is a value calculated as a standard polystyrene as measured by gel permeation chromatography (GPC).

[0038] The resin (A) is typically incorporated into the present composition in the form of an aqueous dispersion or solution. The solids content of the aqueous dispersion or aqueous solution of resin (A) (the content of resin (A) converted into solids content relative to the total mass of the aqueous dispersion or aqueous solution) is preferably 5 to 40 mass%, more preferably 5 to 25 mass%, and particularly preferably 5 to 15 mass%, relative to the total mass of the aqueous dispersion or aqueous solution. When the solids content is at least the lower limit of the above range, the viscosity of the composition can be prevented from becoming too low. When the solids content is at most the upper limit of the above range, the aqueous dispersion can be stabilized, and gelation can be prevented.

[0039] The solid content of the resin (A) is preferably 0.1 to 40 mass %, more preferably 0.1 to 25 mass %, even more preferably 0.1 to 15 mass %, and particularly preferably 0.5 to 10 mass %, relative to the total mass of the composition. By having the solid content within this range, the hydrophilizing effect is fully exerted, and the stain resistance of the coating film is improved. In the aqueous dispersion of resin (A), the particle size of resin (A) is preferably 0.01 to 0.10 μm. If the particle size is within this range, the coating film will have good water resistance. The particle size of the resin (A) is an average particle size measured with a scanning electron microscope.

[0040] [Method for producing resin (A)] The resin (A) can be obtained, for example, by polymerizing a monomer mixture (M) containing the monomer (a1), the monomer (a2) and the monomer (a3). The monomer mixture (M) may contain other monomers as required. The method for polymerizing the monomer mixture (M) is not particularly limited, and known methods such as solution polymerization, suspension polymerization, emulsion polymerization, etc. Among these, solution polymerization is preferred.

[0041] One example of a method for producing resin (A) is to dissolve the monomer mixture (M) in an organic solvent, heat it, react (polymerize) it using a polymerization initiator, cool it, neutralize it if necessary, add water, and remove the organic solvent, thereby obtaining a translucent aqueous dispersion in which fine particles of resin (A) are uniformly dispersed in water. The temperature when reacting the monomer mixture (M) can be, for example, 60 to 90° C. The reaction time can be, for example, 3 to 10 hours.

[0042] When the resin (A) is polymerized by solution polymerization, it is preferable that a part or all of the organic solvent used during the polymerization is a water-soluble organic solvent. Specific examples of water-soluble organic solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 2-methyl-2-propanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, and dimethyl ketone. These may be used alone or in combination of two or more. From the viewpoints of polymerization stability, water substitution property of the solvent, and solvent removal property, 1-propanol or 2-propanol is preferred.

[0043] As the organic solvent used in the polymerization, in addition to the above, known solvents capable of dissolving the monomers (a1), (a2) and (a3) ​​can be used. Examples of organic solvents other than those mentioned above include aromatic hydrocarbons such as toluene, benzene, and xylene; esters such as ethyl acetate, butyl acetate, and propyl acetate; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as dimethyl ketone, methyl ethyl ketone, and methyl isobutyl ketone; and aliphatic alcohols such as isopropanol. The amount of the organic solvent used is not particularly limited, but is preferably 10 to 1000 parts by mass, more preferably 50 to 500 parts by mass, per 100 parts by mass of the monomer mixture (M).

[0044] A polymerization initiator may be used for the polymerization of the monomer mixture (M). The monomer mixture (M) and the polymerization initiator, etc. may be added to the polymerization reaction system all at once, or may be added to the polymerization reaction system in several divided portions at time intervals depending on the progress of the polymerization reaction. From the viewpoint of reducing the residual monomer in the resulting resin (A), it is preferable to add the monomer mixture (M) and the polymerization initiator, etc. to the polymerization reaction system in separate portions.

[0045] As the polymerization initiator used in the polymerization, known initiators can be used, and can be appropriately selected depending on the properties and polymerizability of the resulting resin (A). Examples of the polymerization initiator include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexanecarbonitrile), dimethyl-2,2'-azobis(isobutyrate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-amidinopropene) dihydrochloride, 2-tert-butylazo-2-cyanopropane, 2,2'- Examples of peroxides include azo compounds such as azobis(2-methyl-propionamide) dihydrate, 2,2'-azobis[2-(2-imidazolin-2-yl)propene], and 2,2'-azobis(2,2,4-trimethylpentane); organic peroxides such as benzoyl peroxide, lauroyl peroxide, tert-butyl hydroperoxide, and tert-butyl-α-cumyl peroxide; and inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate. These polymerization initiators may be used alone or in combination of two or more. They can also be used in combination with a reducing agent to accelerate the reaction.

[0046] After polymerization, the resin (A) dispersed or dissolved in the organic solvent may be converted into an aqueous dispersion or solution. The aqueous dispersion or solution can be obtained by adding water and removing the organic solvent. In this case, an optional neutralizing agent may be added, if necessary. Examples of the neutralizing agent include ammonia, sodium hydroxide, potassium hydroxide, triethylamine, triethanolamine, and aminomethylpropanol. The neutralizing agent may be used alone or in combination of two or more. Ammonia is preferred from the viewpoint of the water resistance and stain resistance of the coating film.

[0047] <Colloidal silica> The composition preferably further contains colloidal silica, as this improves the stain resistance of the coating film. There are no particular limitations on the type of colloidal silica, but water-dispersed colloidal silica is preferred. Examples of water-dispersed colloidal silica include the Snowtex series (such as Snowtex ST-NXS) manufactured by Nissan Chemical Industries, Ltd.

[0048] The solid content of the colloidal silica contained in the composition is preferably 100% by mass or more, and more preferably 200% by mass or more, relative to 100% by mass of the solid content of the resin (A). The solid content of the colloidal silica contained in the composition is preferably 500% by mass or less, and more preferably 400% by mass or less, relative to 100% by mass of the solid content of the resin (A). When the colloidal silica content is within the above range, the stain resistance is further improved, and the stain resistance of the coating film is maintained for a long time.

[0049] <Monomer (a4)> The present composition preferably further contains a monomer (a4) having one or more alkoxysilyl groups, as this improves the durability of the stain resistance of the coating film. Specific examples of the monomer (a4) include those described for the monomer (a3). These may be used alone or in combination of two or more.

[0050] Among these, those having an amino group or an epoxy group are preferred because they improve the durability of stain resistance. Specifically, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and the like are preferred.

[0051] The solid content of the monomer (a4) contained in the composition is preferably 1% by mass or more, more preferably 2% by mass or more, based on 100% by mass of the solid content of the resin (A). The solid content of the monomer (a4) contained in the composition is preferably 20% by mass or less, more preferably 15% by mass or less, based on 100% by mass of the solid content of the resin (A). When the content of the monomer (a4) is within the above range, the stain resistance is further improved, and the stain resistance of the coating film is maintained for a long time.

[0052] <Decolorable colorant> It is preferable that the present composition further contains a decolorizable colorant, as this makes it easier to visually distinguish between painted and unpainted areas, improves painting workability, and makes it easier to apply uniformly. The decolorizable coloring agent is not particularly limited as long as it is one that is decolorized by light such as sunlight or water such as rainfall, but natural pigments, food pigments, topical medicines, quasi-drugs, and legally approved pigments for cosmetics can be used.

[0053] Natural pigments include turmeric pigment, gardenia yellow, safflower yellow, beta-carotene, monascus yellow, marigold pigment, lac pigment, cochineal pigment, monascus pigment, beet red, red cabbage pigment, gardenia red pigment, purple sweet potato pigment, red radish pigment, grape skin pigment, perilla pigment, elderberry pigment, purple corn pigment, safflower red pigment, chili pepper pigment, annatto pigment, green coloring preparations such as gardenia and safflower, chlorophyll, gardenia blue pigment, squid ink pigment, plant charcoal powder pigment, cacao pigment, tamarind pigment, and persimmon pigment.

[0054] Examples of food dyes include Food Red No. 2, Food Red No. 3, Food Red No. 40, Food Red No. 102, Food Red No. 104, Food Red No. 105, Food Red No. 106, Food Yellow No. 4, Food Yellow No. 5, Food Green No. 3, Food Blue No. 1, Food Blue No. 2, Food Red No. 2 Aluminum Lake, Food Red No. 3 Aluminum Lake, Food Red No. 40 Aluminum Lake, Food Yellow No. 4 Aluminum Lake, Food Yellow No. 5 Aluminum Lake, Food Green No. 3 Aluminum Lake, Food Blue No. 1 Aluminum Lake, and Food Blue No. 2 Aluminum Lake.

[0055] Legal dyes for external use in medicines, quasi-drugs, and cosmetics include Red No. 2, Red No. 3, Red No. 40, Red No. 102, Red No. 104 (1), Red No. 105 (1), Red No. 106, Yellow No. 4, Yellow No. 5, Green No. 3, Blue No. 1, Blue No. 2, Red No. 3 Aluminum Lake, Yellow No. 4 Aluminum Lake, Yellow No. 5 Aluminum Lake, Blue No. 1 Aluminum Lake, Blue No. 2 Aluminum Lake, Red No. 226, Red No. 227, Red No. 230 (1), Orange No. 205, Yellow No. 202 (1), Yellow No. 203, Green No. 201, Green No. 204, Red No. 504, Purple No. 401, and Black No. 401.

[0056] In addition to the above, examples of decolorizing coloring agents include food dyes such as Sea Urchin Color SS-8, Golden Brown SN-8, Melon Color, Melon Green T, Ground Brown, Food Red No. 106 5% Solution, and Grape Color, all manufactured by Daiwa Chemical Industry Co., Ltd. Other examples include dyes such as Carmosine, Quinoline Yellow, Green S, Patent Blue V, and Brown HT. Among these, the above-mentioned natural dyes, food dyes, and legally approved dyes for topical drugs, quasi-drugs, and cosmetics are preferred because of their environmental safety, storage stability, and decolorization properties, and Monascus color and Monascus yellow are particularly preferred.

[0057] The solid content of the decolorizing colorant contained in the composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, based on 100% by mass of the composition including nonvolatile and volatile components. The solid content of the decolorizing colorant contained in the composition is preferably 5% by mass or less, more preferably 3% by mass or less, based on 100% by mass of the composition including nonvolatile and volatile components. When the content of the decolorizable colorant is equal to or greater than the lower limit, the visibility is improved and the coating workability is improved. When the content of the decolorizable colorant is equal to or less than the upper limit, the decolorization of the colorant after forming the coating film is improved.

[0058] <Photocatalytic semiconductor materials> When the composition contains a decolorizable colorant, it is preferable that the composition does not contain a photocatalytic semiconductor material, such as TiO2, ZnO, SnO2, SrTiO3, WO3, Bi2O3, or Fe2O3, because this impairs the outdoor stability of the decolorizable colorant.

[0059] When a photocatalytic semiconductor material is contained together with a decolorizable colorant, the color of the decolorizable colorant becomes lighter and the time it takes for the color to fade after application becomes shorter, making it difficult to see the painted areas. In addition, when a photocatalytic semiconductor material is unavoidably contained, it is regarded as not containing a photocatalytic semiconductor material. When a photocatalytic semiconductor material is unavoidably contained, the proportion thereof is preferably 0.1 mass% or less, and more preferably 0.01 mass% or less, relative to 100 mass% of the solid content of the resin (A).

[0060] <Algae prevention agent / mold prevention agent> The composition preferably contains an anti-algae agent and / or an anti-fungal agent, since this improves the organism resistance. Known anti-algae agents and anti-fungal agents can be used. Examples of the anti-algae or anti-fungal agent include isothiazolinone-based anti-algae or anti-fungal agents, urea-based anti-algae or anti-fungal agents, triazine-based anti-algae or anti-fungal agents, benzimidazole-based anti-algae or anti-fungal agents, pyridine-based anti-algae or anti-fungal agents, zinc pyrithione-based anti-algae or anti-fungal agents, and thiazole-based anti-algae or anti-fungal agents.

[0061] Examples of isothiazoline-based anti-algae or anti-fungal agents include 2-n-octyl-4-isothiazolin-3-one, 5-dichloro-2-n-octyl-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one, and Nn-butyl-1,2-benzisothiazolin-3-one.

[0062] Examples of urea-based anti-algae agents or anti-fungal agents include 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 3-(3,4-dichlorophenyl)-1-methyl-1-methoxyurea, 3-(3,4-dichlorophenyl)-1-(2-methylcyclohexyl), 3-phenyl-1-(2-methylcyclohexyl)urea, and 3-(phenyldimethylmethyl)-1-(4-methylphenyl)urea.

[0063] Examples of triazine-based anti-algae agents or anti-fungal agents include 2-chloro-4,6-bis(ethylamino)-1,3,5-triazine, 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine, 2-methylthio-4,6-bis(ethylamino)-S-triazine, 2-methylthio-4-ethylamino-6-isopropylamino-S-triazine, 2-methylthio-4,6-bis(isopropylamino)-S-triazine, 2-methylthio-4-t-butylamino-6-cyclopropylamino-S-triazine, and N'-t-butyl-N-cyclopropyl-6-(methylthio)-1,3,5-triazine-2,4-diamine.

[0064] Examples of benzimidazole-based anti-algae or anti-fungal agents include thiuram disulfide-based agents such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetraisopropylthiuram disulfide, dipyrrolidone thiuram disulfide, and polyethylene thiuram disulfide; 2-(4-thiazyl)benzimidazole, and 2-(carbomethoxyamino)benzimidazole.

[0065] Examples of pyridine-based anti-algae agents or anti-fungal agents include 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine. Examples of zinc pyrithione-based anti-algae agents or anti-fungal agents include zinc-2-pyrithinethiol-1-oxide.

[0066] Examples of thiazole-based anti-algae agents or anti-fungal agents include 2-(4-thiocyanomethylthio)benzothiazole. In addition, organic halogen-based, organic metal-based, haloalkylthio-based, and phenylphenol-based anti-algae agents or anti-fungal agents can be used.

[0067] These anti-algae agents or anti-fungal agents may be used alone or in combination of two or more. Among these, triazine-based and isothiazolin-based compounds are preferred from the viewpoint of improving the durability of the anti-algae and anti-fungal effects, as they do not easily leave a residual color when applied to the exterior and do not affect the exterior design.

[0068] The solid content of the anti-algae agent and / or anti-fungal agent in the composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, relative to 100 parts by mass of the total solid content of the composition. The solid content of the anti-algae agent and / or anti-fungal agent in the composition is preferably 10% by mass or less, more preferably 5% by mass or less, relative to 100 parts by mass of the total solid content of the composition. If the content of the anti-algae agent and / or anti-fungal agent is equal to or greater than the lower limit, the organism resistance of the coating film will be good. If the content of the anti-algae agent and / or anti-fungal agent is equal to or less than the upper limit, the safety for painting workers will be good.

[0069] <Optional ingredients> The composition may contain known additives as needed, such as emulsifiers, pH adjusters, antifoaming agents, viscosity adjusters, film-forming aids, antifreeze agents, dispersants, wetting agents, penetration aids, preservatives, surface conditioners, matting agents, UV absorbers, antioxidants, and heat-shielding agents.

[0070] <Painting method> The composition is applied to a substrate and dried to form a coating film. The substrate is not particularly limited, and can be applied to a variety of objects, including ceramic building boards such as ceramic siding boards, flexible boards, calcium silicate boards, gypsum slag barite boards, wood chip cement boards, asbestos cement boards, pulp cement boards, precast concrete boards, lightweight aerated concrete (ALC) boards, and gypsum boards, metal building boards such as aluminum, iron, and stainless steel, mortar, plastic, wood, and paper. These may have surfaces that have been subjected to a primer treatment with a sealer or primer. These may also have surfaces on which a primer coating film or a topcoat coating film has been formed.

[0071] The method for applying the present composition is not particularly limited, and the composition can be applied by any known application method such as brushing, troweling, roller, spray coating, roll coating, flow coating, etc. Among these, spray coating is preferred because it can form a thin and uniform coating film. The amount of the composition to be applied can be appropriately selected depending on the average thickness of the coating film to be formed, but the mass per unit area before drying (wet) is 20 g / m 2 More than 25g / m is preferable. 2 More preferably, 30 g / m 2 More than 200 g / m 2 Preferably less than 150 g / m 2 Less than 100 g / m is more preferable. 2 The following are particularly preferred: When the coating amount is equal to or greater than the lower limit, a coating film having good durability and stain resistance can be formed. When the coating amount is equal to or less than the upper limit, a coating film having good durability and stain resistance can be formed without impairing the appearance of the painted base.

[0072] Since it is preferable to apply the present composition thinly and uniformly, it is preferable to apply the above-mentioned amount in two or more applications. The drying may be performed at room temperature or by heating, as long as the aqueous medium can be removed. In the case of room temperature drying, the temperature is preferably about 5 to 40°C. In the case of heated drying, the temperature is, for example, 40 to 90°C. The drying time varies depending on the drying temperature, but is, for example, 5 minutes to 48 hours.

[0073] <Action and effect> The present antifouling composition of the above embodiment contains the above-mentioned resin (A), and therefore can form a coating film that combines biological resistance and fouling resistance for a longer period than conventional ones. The present antifouling composition can further exhibit the above-mentioned effects by further containing colloidal silica and / or monomer (a4).

[0074] The present composition has a coating film that is hydrophilic due to the hydrophilic functional group derived from the monomer (a2) contained in the resin (A), and therefore has good stain resistance. Furthermore, by containing alkoxysilyl groups derived from monomer (a3) ​​in resin (A), the alkoxysilyl groups are partially bonded to hydrophilic functional groups, or to each other, resulting in a coating film with intermolecular crosslinking. Therefore, even if the surface layer of the coating film is washed away by rain or other factors, the coating film is less likely to be washed away in a short period of time, and stain resistance can be maintained for a long period of time.

[0075] When the present composition contains colloidal silica, the coating film becomes more hydrophilic, and the stain resistance of the coating film can be further improved. Furthermore, the presence of alkoxysilyl groups derived from monomer (a3) ​​in resin (A) allows the alkoxysilyl groups to bond with the hydroxyl groups of the colloidal silica, making the coating less likely to wash away in a short period of time and allowing the coating to maintain stain resistance for a long period of time compared to coatings made solely from colloidal silica.

[0076] When the composition contains monomer (a4), the stain resistance of the coating film can be made to last longer. The alkoxysilyl groups contained in monomer (a4) bond with the hydrophilic groups and alkoxysilyl groups contained in resin (A) (and with the hydroxyl groups of the colloidal silica, if the composition contains colloidal silica). This results in a coating film in which the resin (A) (and, if colloidal silica is included, the colloidal silica) is more highly cross-linked between its molecules, making the coating film less likely to wash away in a short period of time and allowing it to maintain its stain resistance for a longer period of time.

[0077] Furthermore, if the molecular weight of resin (A) is not too large, the hydrophilic coating film surface will gradually wash away, and even in places where biological fouling is likely to occur, such as on the north side of a building or in a humid environment, the biologically fouled coating film will wash away, resulting in good biological resistance. [Example]

[0078] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. In the following description, "parts" means "parts by mass" and "%" means "% by mass" except for relative humidity.

[0079] <Raw materials> Polymerization initiator: "ABN-E" manufactured by Japan Finechem Co., Ltd., 2,2'-azobis(2-methylbutyronitrile). Colloidal silica: Nissan Chemical Co., Ltd.'s "Snowtex ST-50-T", solid content 48%. - Decolorizing coloring agent: Daiwa Monas LA-R, manufactured by Daiwa Chemical Co., Ltd., 50% solids. Photocatalytic titanium dioxide: Ishihara Sangyo Kaisha, Ltd., "STS-21", water dispersion, active ingredient 40%, particle size 20nm.

[0080] Resin (B): DIC Corporation's "Boncoat SA-6340", acrylic silicone resin emulsion, solid content 50%. Calcium carbonate A: Nitto Funka Kogyo Co., Ltd., "NS#2300", average particle size 1 μm. Calcium carbonate B: Sankyo Seifun Co., Ltd., "G-100", average particle size 65 μm. White pigment: Teika Corporation's "JR-806", titanium dioxide, average particle size 0.25 μm. Dispersant: Dow Chemical Company, Orothane® 731A, anionic polymeric dispersant, 25% solids. UV absorber: Tinuvin 477DW, BASF JAPAN Ltd., active ingredient 40% Light stabilizer: Tinuvin 123, BASF JAPAN Ltd., 100% active ingredient Thickener: Dow Chemical Company's "QP52000H", hydroxyethyl cellulose, 1% by weight aqueous solution. Film-forming agent: Texanol (registered trademark), manufactured by Eastman Chemical. Antifoaming agent: San Nopco's "SN Deformer 1316", 100% solids.

[0081] <Preparation of Resin (A)> [Resin A-1] A 3 L round-bottom flask equipped with a stirrer was charged with 250 parts of 2-propanol, 1 part of methyl methacrylate, 50 parts of methacrylic acid, 42 parts of hydroxyethyl acrylate, and 7 parts of 3-methacryloxypropylmethyldimethoxysilane, and the mixture was heated with stirring to 75°C. 2 parts of a polymerization initiator was then charged to initiate the reaction.

[0082] The mixture was allowed to react at an internal temperature of 75°C for 5 hours, cooled, and then 7 parts of 25% aqueous ammonia and 900 parts of water were added at 40°C or below and stirred until homogenous, yielding a liquid with a solid content of 8%. 2-Propanol was distilled off from this liquid using a rotary evaporator, yielding an aqueous resin (A-1) with a solid content of 10% and a weight-average molecular weight of 100,000.

[0083] [Resin A-2 to A-11] Aqueous resins A-2 to A-11 were obtained in the same manner as for resin A-1, except that the amounts (parts) of the raw materials used were changed as shown in Table 1. Note that blank spaces in Table 1 indicate that the component was not used in the preparation. The weight average molecular weight of each resin is shown in Table 1.

[0084] <Examples and Comparative Examples> The antifouling coating compositions of each example were produced by mixing and stirring the raw materials in a conventional manner according to the formulations shown in Tables 2 and 3. Note that blank spaces in Tables 2 and 3 indicate that the component in question was not blended.

[0085] <Production of enamel paint> A white enamel paint was produced by mixing and stirring the raw materials according to the formulation shown in Table 4 in a conventional manner.

[0086] <Evaluation> The following evaluations were carried out, and the results are shown in Tables 2 and 3.

[0087] [Evaluation of contamination resistance] An aluminum plate (225 x 100 x 1 mm) was bent at a position one-third of the way from one end of the long side along the short side to an internal angle of 135°, and a solvent-based urethane primer (two-component) was applied to the convex surface, followed by drying at room temperature for one day.

[0088] Next, the prepared enamel paint (white) was applied at a rate of 300 g / m 2 The paint was applied with an air spray so that the surface was wet, and then allowed to dry for 24 hours at a temperature of 23°C and a relative humidity of 50%. After that, an enamel paint prepared under the same conditions was applied again, and then allowed to dry for 24 hours at a temperature of 23°C and a relative humidity of 50%.

[0089] Next, the antifouling coating composition of each example was applied on the formed enamel paint film in an amount of 30 g / m 2 The coating was applied with an air spray so that the surface was wet, and then dried for 24 hours at a temperature of 23°C and a relative humidity of 50%, after which the antifouling coating composition of each example was applied again under the same conditions, and the coating was dried for 14 days at a temperature of 23°C and a relative humidity of 50%.

[0090] This resulted in a test specimen having an undercoat film, an enamel film, and an antifouling coating composition film formed in this order on the aluminum plate. The test specimens were exposed vertically to the south side on the premises (outdoors) of Fujikura Kasei Co., Ltd. in Sakurada, Kuki City, Saitama Prefecture. After six months and two years, the appearance of the coating on the test specimens was visually inspected and evaluated according to the following criteria.

[0091] (Evaluation criteria for stain resistance) 4: No contamination was found and the condition was good. 3: Some contamination was observed, but overall the condition was good. 2: Some contamination was observed, but to an extent that was not a problem for practical use. 1: Overall contamination confirmed.

[0092] [Biological resistance evaluation] First, apply 100g / m of "FC Coat Cationic Sealer" (a water-based acrylic emulsion cationic sealer manufactured by Fujikura Kasei Co., Ltd.). 2A smooth slate board (300 x 15 x 3 mm) was painted with a roller to achieve a wet finish, and enamel paint (white) was applied at a rate of 300 g / m. 2 The paint was applied with an air spray so that the surface was wet, and then allowed to dry for 24 hours at a temperature of 23°C and a relative humidity of 50%. After that, an enamel paint prepared under the same conditions was applied again, and then allowed to dry for 24 hours at a temperature of 23°C and a relative humidity of 50%.

[0093] Next, the antifouling coating composition of each example was applied on the formed enamel paint film in an amount of 30 g / m 2 The coating was applied with an air spray so that the surface was wet, and then dried for 24 hours at a temperature of 23°C and a relative humidity of 50%, after which the antifouling coating composition of each example was applied again under the same conditions, and the coating was dried for 14 days at a temperature of 23°C and a relative humidity of 50%.

[0094] This resulted in a test specimen having a sealer coating film, an enamel coating film, and an antifouling coating composition coating film formed in this order on the slate board. This test specimen was exposed vertically to the north side of a field surrounded by lush vegetation on the premises (outdoors) of Fujikura Kasei Co., Ltd. in Sakurada, Kuki City, Saitama Prefecture. After one year, the appearance of the coating film on the test specimen was visually observed and evaluated according to the following criteria.

[0095] (Evaluation criteria for biological resistance) ○: No contamination by algae or mold was found. ×: Contamination by algae or mold was confirmed.

[0096] [Evaluation of decolorization] In the same manner as in the evaluation of biological resistance, a sealer coating film and a coating film of the prepared enamel paint were formed on a slate board. Next, the antifouling coating composition of each example was applied on the formed enamel paint film in an amount of 30 g / m 2 The coating was applied with an air spray so that the coating was wet. The test specimen was exposed to sunlight outdoors on the premises of Fujikura Kasei Co., Ltd. in Sakurada, Kuki City, Saitama Prefecture, with the coating surface facing south. The decolorization was evaluated according to the following criteria.

[0097] (Evaluation criteria for decolorization) ◯: The color of the colored coating composition film remained for 30 minutes or more, but disappeared within 3 days. ×: The color of the colored coating composition film disappeared in less than 30 minutes.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] [Table 4]

[0102] As shown in Table 2, in all of the Examples, the stain resistance continued not only after six months of exposure but also after two years. There were also no problems with biological resistance or decolorization. However, in Example 1, since the coating composition did not contain colloidal silica, the hydrophilicity of the coating film was slightly inferior, and some staining was observed in the coating film after six months of exposure.Furthermore, since the coating composition did not contain monomer (a4), some staining was observed in the coating film after two years of exposure, resulting in slightly inferior durability of stain resistance.

[0103] In Example 2, since the coating composition did not contain the monomer (a4), some staining was observed on the coating film after two years of exposure, resulting in slightly poorer durability of stain resistance. In Example 3, the coating composition did not contain colloidal silica, so the hydrophilicity of the coating film was slightly inferior, and some staining was observed on the coating film after six months of exposure.

[0104] In Example 4, the content of monomer (a1) in resin (A) was high and the content of monomer (a2) in resin (A) was low, resulting in slightly poor stain resistance after 6 months and 2 years of exposure. In addition, the content of monomer (a3) ​​in resin (A) was high, resulting in slightly poor storage stability of resin (A). In Example 7, the content of monomer (a1) in resin (A) was low, the content of monomer (a2) was high, and the content of monomer (a3) ​​was low, resulting in a slightly poorer durability of the stain resistance of the coating film.

[0105] On the other hand, as shown in Table 3, Comparative Examples 1 and 6, which did not contain the resin (A) in the coating composition, showed poor stain resistance even after six months of exposure. Comparative Example 2, in which the content of monomer (a1) units in resin (A) was low, had low stain resistance after two years of exposure and was poor in the durability of stain resistance. Comparative Example 3, in which the content of monomer (a2) units in resin (A) was low, had poor stain resistance even after six months of exposure. Comparative Example 4, in which resin (A) did not contain monomer (a3) ​​units, had low stain resistance after two years of exposure and was poor in the durability of stain resistance. Comparative Example 5, in which the molecular weight of resin (A) was high, had poor biological resistance. Furthermore, Reference Example 1, which contained photocatalytic titanium oxide in the coating composition, had a problem with decolorization.

Claims

1. An antifouling coating composition comprising a resin (A) and a monomer (a4), the resin (A) contains a unit derived from a monomer (a1), a unit derived from a monomer (a2), and a unit derived from a monomer (a3), and has a weight average molecular weight of 10,000 or more and 200,000 or less; the monomer (a1) is at least one selected from the group consisting of alkyl acrylates and alkyl methacrylates, the monomer (a2) is an ethylenically unsaturated monomer having one or more hydrophilic functional groups, the monomer (a3) ​​is a monomer having one or more alkoxysilyl groups, the proportion of units derived from the monomer (a1) in the total mass of all units constituting the resin (A) is 4.9 to 30 mass%, the proportion of units derived from the monomer (a2) in the total mass of all units constituting the resin (A) is 55 to 95 mass%, the proportion of units derived from the monomer (a3) ​​in the total mass of all units constituting the resin (A) is 0.1 to 15 mass%, the monomer (a4) is a monomer having one or more alkoxysilyl groups, an antifouling coating composition, wherein the proportion of the solid content of the monomer (a4) is 1 to 20 mass% relative to 100 mass% of the solid content of the resin (A).

2. The antifouling coating composition according to claim 1 , further comprising colloidal silica.

3. The antifouling coating composition according to claim 1 or 2, which further contains a decolorizable colorant in addition to the resin (A) and does not contain a photocatalytic semiconductor material.

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