Emulsion-type aqueous Anti-biofilm coating agent and method for producing same, and Anti-biofilm laminate and method for producing same

Abstract

[Problem] The purpose of the present invention is to provide: an emulsion-type aqueous anti-biofilm coating agent that imparts an excellent anti-biofilm effect and coating film water resistance to the surface of a substrate; a method for producing the same; an anti-biofilm laminate having a layer comprising the aqueous anti-biofilm coating agent; and a method for producing the same. [Solution] An emulsion-type aqueous anti-biofilm coating agent that meets all the specified requirements contains a polymer [A], a surfactant [B], and water. A method for producing the same is also provided.

Description

Emulsion-type aqueous anti-biofilm coating agent and its manufacturing method, and anti-biofilm laminate and its manufacturing method

[0001] The present invention relates to an emulsion-type aqueous anti-biofilm coating agent and a method for producing the same, and also to an anti-biofilm laminate having a layer made of the aqueous anti-biofilm coating agent and a method for producing the same.

[0002] A biofilm is a structure formed by bacteria, also known as slime or bacterial film. Biofilm formation occurs as follows: First, bacteria attached to a substrate in water secrete extracellular polysaccharides and proteins. These act as a barrier and transport pathway, protecting the bacteria inside from environmental changes and chemicals. It is believed that bacteria repeatedly attach to and detach from the substrate, gradually forming a biofilm on the surface of the substrate.

[0003] Once formed, biofilms exhibit extremely high resistance to cleaning / removal, antibiotics, chemicals, heat, drying, etc. As a result, the attached and proliferated microorganisms can cause harm and cause problems in various industrial fields, so there is a demand for technology to suppress the formation of biofilms on substrate surfaces, in other words, anti-biofilm effects.

[0004] Considering the mechanism of biofilm formation, one possible method for imparting anti-biofilm effects to substrate surfaces is the application of a coating agent that forms a coating film that inhibits bacterial adhesion. Coating agents include oil-based coating agents using volatile organic solvents and water-based coating agents. However, if the coating equipment is not equipped with a solvent recovery (treatment) device, the solvent components of the coating agent will be emitted into the atmosphere during drying after application. Because volatile organic compounds (VOCs) emitted into the atmosphere are associated with various environmental issues, such as photochemical oxidant generation, stratospheric ozone depletion, and global warming, there has been a trend in recent years toward water-based coating agents, even for common water-based coating agents.

[0005] As an aqueous anti-biofilm coating agent, for example, Patent Document 1 proposes a method of suppressing biofilm formation by coating a substrate with a cationic polymer having a specific structure. However, this method results in a coating film with low water resistance, making it difficult to use for a long period of time in water where biofilms are likely to form.

[0006] Furthermore, Patent Document 2 proposes an aqueous polymer emulsion that suppresses the generation or adhesion of dirt in wet areas. Patent Document 3 proposes an aqueous polymer emulsion that uses a surfactant with a specific structure to suppress yellowing of coating films at high temperatures. However, all of these prior art technologies have insufficient anti-biofilm effects.

[0007] JP 2020-026391 A JP 2021-116407 A JP 2004-107478 A

[0008] The present invention aims to provide an emulsion-type aqueous anti-biofilm coating agent that imparts excellent anti-biofilm effect and coating water resistance to the surface of a substrate, a method for producing the same, and an anti-biofilm laminate having a layer made of the aqueous anti-biofilm coating agent, and a method for producing the same.

[0009] As a result of intensive research to solve the above problems, the inventors discovered that by applying an emulsion-type aqueous anti-biofilm coating agent containing a polymer and a surfactant having a specific structure, as well as water, it is possible to provide the substrate surface with excellent anti-biofilm effects and coating water resistance, and thus completed the present invention.

[0010] That is, the present invention, which is a means for solving the above-mentioned problems, provides: <1> an emulsion-type aqueous anti-biofilm coating agent comprising a polymer [A], a surfactant [B], and water, and characterized in that it satisfies all of the following (1) to (3): (1) the polymer [A] contains 30 to 100 mass % of alkyl (meth)acrylate [a] having 1 to 4 carbon atoms as a structural unit; (2) the surfactant [B] contains 50 to 100 mass % of at least one selected from the following [b-1] and [b-2] relative to the total amount of [B]: [b-1] as a molecular structure -COOM １ and -CH ２ CH ２ Compounds having O- [b-2] molecular structure -COOM １ and -SO ３ M ２ A compound having the formula １ , M ２ are H, Na, K, NH ４ (3) The emulsion particles are composed of at least a polymer [A] and a surfactant [B], and the particle diameter is 50 to 300 nm. <2> The emulsion-type aqueous anti-biofilm coating agent according to <1>, characterized in that the mass ratio of the polymer [A] and the surfactant [B] is [A] / [B]=100 / 1 to 10. <3> The emulsion-type aqueous anti-biofilm coating agent according to <1>, characterized in that the surfactant [B] contains 50 to 100 mass% of polyoxyethylene lauryl ether acetic acid or a salt thereof relative to the total amount of [B]. <4> A method for obtaining an emulsion-type aqueous anti-biofilm coating agent containing a polymer [A] by emulsion polymerization of a monomer mixture in the presence of a surfactant [B] and water, wherein the monomer mixture contains 30 to 100 mass% of an alkyl(meth)acrylate [a] having 1 to 4 carbon atoms, A method for producing an emulsion-type aqueous anti-biofilm coating agent, characterized in that the surfactant [B] contains at least one selected from the following [b-1] and [b-2] in an amount of 50 to 100% by mass relative to the total amount of [B], [b-1] having a molecular structure of -COOM １ and -CH ２ CH ２Compounds having O- [b-2] molecular structure -COOM １ and -SO ３ M ２ A compound having the formula １ , M ２ are H, Na, K, NH ４ <5> An anti-biofilm laminate having, on a surface of a substrate, a layer made of the emulsion-type aqueous anti-biofilm coating agent described in any one of <1> to <3>; <6> A method for producing an anti-biofilm laminate, comprising a step of applying, to a surface of a substrate, the emulsion-type aqueous anti-biofilm coating agent described in any one of <1> to <3>.

[0011] According to the present invention, it is possible to provide an emulsion-type aqueous anti-biofilm coating agent that can impart excellent anti-biofilm effect and coating water resistance to a substrate surface. An anti-biofilm laminate obtained by applying this aqueous anti-biofilm coating agent to a substrate surface has sufficient coating water resistance and can maintain the anti-biofilm effect even when used for a long period of time in water where biofilms are likely to form, so that frequent cleaning of the substrate surface is not required and maintenance is easy.

[0012] The emulsion-type aqueous anti-biofilm coating agent of the present invention contains a polymer [A], a surfactant [B], and water.

[0013] Polymer [A] must contain 30 to 100% by mass of the structural unit of alkyl (meth)acrylate [a] having 1 to 4 carbon atoms. In the present invention, alkyl (meth)acrylate [a] having 1 to 4 carbon atoms refers to a (meth)acrylic acid ester in which the alkyl group constituting the ester moiety has 1 to 4 carbon atoms. Examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, and isobutyl (meth)acrylate. These may be used alone or in combination of two or more. If the content of alkyl (meth)acrylate [a] having 1 to 4 carbon atoms in polymer [A] is less than 30% by mass, the anti-biofilm effect is not fully exerted. 50 to 100% by mass is preferred, and 70 to 100% by mass is more preferred. In this specification, the term "(meth)acrylate" has the same meaning as "acrylate or methacrylate."

[0014] The polymer [A] may contain structural units of hydrophobic vinyl monomers other than the alkyl(meth)acrylate [a] having 1 to 4 carbon atoms in the range of 0 to 70% by mass. Examples of hydrophobic vinyl monomers other than the alkyl(meth)acrylate [a] having 1 to 4 carbon atoms include styrenes such as styrene, α-methylstyrene, vinyltoluene, and divinylbenzene; alkyl(meth)acrylates having 5 or more carbon atoms such as octyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, lauryl(meth)acrylate, and stearyl(meth)acrylate; cyclic alkyl(meth)acrylates such as cyclohexyl(meth)acrylate and benzyl(meth)acrylate; dialkyl diesters of maleic acid and fumaric acid; vinyl esters such as vinyl acetate and vinyl propionate; N-alkyl(meth)acrylamides; (meth)acrylonitrile; methyl vinyl ethers; and halogen-containing ethylenes such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride. These may be used alone or in combination of two or more. Among these, styrenes and alkyl (meth)acrylates having 5 or more carbon atoms are preferred because they are easily available industrially.

[0015] For the purpose of reducing fouling during production, polymer [A] may be a copolymer of the above-mentioned [a] and a hydrophilic vinyl monomer copolymerizable with a hydrophobic vinyl monomer other than [a]. From the viewpoint of the water resistance of the anti-biofilm coating layer, the amount of the hydrophilic vinyl monomer in polymer [A] is preferably 0.5 to 5 mass %, more preferably 1 to 3 mass %. Examples of hydrophilic vinyl monomers include nonionic monomers such as (meth)acrylamides, N-vinylpyrrolidone, hydroxyalkyl (meth)acrylates, and methoxypolyethylene glycol (meth)acrylates; monomers having a carboxylic acid group such as (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and crotonic acid; monomers having a sulfonic acid group such as vinyl sulfonic acid, (meth)allyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and sulfonated styrene; and monomers having a phosphate group such as phosphate esters of hydroxyalkyl (meth)acrylates. Among these, hydroxyalkyl (meth)acrylates, methoxypolyethylene glycol (meth)acrylates, and monomers having a carboxylic acid group are preferred, and 2-hydroxyethyl methacrylate, 2-methoxyethyl acrylate, and methacrylic acid are even more preferred. These may be used alone or in combination of two or more.

[0016] In addition to the above-mentioned monomers, the polymer [A] may contain structural units of the chain transfer agent or crosslinking agent used during polymerization of the polymer [A], in order to optimize the molecular structure of the polymer [A] and the fluidity of the emulsion. The amount of such a structural unit is preferably within 3 mass % of the polymer [A].

[0017] Examples of the chain transfer agent include alkyl mercaptans, thioglycolic acid and its esters, isopropyl alcohol, etc. Among these, alkyl mercaptans are particularly preferred.

[0018] Crosslinking agents include diallyl phthalate, diallyl hexahydroxyl phthalate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and Examples include monomers having two polymerizable double bonds in the molecule, such as divinylbenzene, monomers having three polymerizable double bonds in the molecule, such as tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate, monomers having four polymerizable double bonds in the molecule, such as pentaerythritol tetra(meth)acrylate, and monomers having five polymerizable double bonds in the molecule, such as dipentaerythritol penta(meth)acrylate, and these may be used alone or in combination of two or more. Of these, divinylbenzene is particularly preferred.

[0019] The glass transition temperature (hereinafter sometimes simply referred to as "Tg") of the polymer [A] is not particularly limited, but from the viewpoint of film-forming properties and blocking resistance, it is preferably within the range of -10 to 70°C. Tg is calculated by the following FOX formula:

[0020] 1 / Tg=W1 / Tg1+W2 / Tg2+ ... +Wn / Tgn (1) [In the formula, Tg is the glass transition temperature (unit: K) of the polymer, Tgi (i = 1, 2, ... n) is the glass transition temperature (unit: K) when monomer i forms a homopolymer, and Wi (i = 1, 2, ... n) is the mass fraction of monomer i in all monomers.] The glass transition temperatures when each monomer forms a homopolymer are, for example, as follows: Styrene: 100°C (373K) Methyl acrylate: 8°C (281K) Methyl methacrylate: 105°C (378K) Ethyl acrylate: -20°C (253K) n-Butyl acrylate: -55°C (218K) n-Butyl methacrylate: 22°C (295K) t-Butyl acrylate: 14°C (287K) 2-Ethylhexyl acrylate: -70°C (203K) 2-Ethylhexyl methacrylate: -10°C (263K) Cyclohexyl methacrylate: 83°C (356K) Vinylidene fluoride: -35°C (238K) N-Octyl acrylamide: 79°C (352K) 2-Methoxyethyl acrylate: -50°C (223K) 2-Hydroxyethyl methacrylate: 55°C (328K) Methacrylic acid: 228°C (501K)

[0021] The surfactant [B] must contain at least one selected from the following [b-1] and [b-2] in an amount of 50 to 100% by mass based on the total amount of [B]. [b-1] The molecular structure of [b-1] is -COOM １ and -CH ２ CH ２ Compounds having O- [b-2] molecular structure -COOM １ and -SO ３ M ２ A compound having the formula １ , M ２ are H, Na, K, NH ４ If the proportion of at least one selected from [b-1] and [b-2] is less than 50% by mass relative to the total amount of [B], the anti-biofilm effect will not be sufficient.

[0022] [b-1] Molecular structure: -COOM １ and -CH ２ CH２ The surfactant [B], which is a compound having O—, includes polyoxyethylene alkyl ether acetic acid and its neutralized salt.

[0023] [b-2] Molecular structure: -COOM １ and -SO ３ M ２ Examples of the surfactant [B] which is a compound having the formula include alkyl sulfosuccinate and neutralized salts thereof.

[0024] Molecular structure: COOM １ , -CH ２ CH ２ O- and -SO ３ M ２ Examples of surfactants [B] having the formula (corresponding to both [b-1] and [b-2]) include polyoxyethylene alkyl sulfosuccinate and neutralized salts thereof.

[0025] Among the above, it is preferable that the proportion of polyoxyethylene lauryl ether acetic acid or its neutralized salt in the surfactant [B] is within the range of 50 to 100% by mass, since this provides a particularly excellent anti-biofilm effect. The proportion of polyoxyethylene lauryl ether acetic acid or its neutralized salt is more preferably 70 to 100% by mass, and even more preferably 85 to 100% by mass.

[0026] The surfactant [B] may contain an anionic or nonionic surfactant other than the compounds selected from [b-1] and [b-2] in an amount of 0 to 50% by mass relative to the total amount of [B]. The type of surfactant to be combined affects the stability of the emulsion particles after emulsion polymerization and production, and can be changed as needed depending on the required performance and quality. However, if only the anti-biofilm effect is taken into consideration, the proportion is preferably as low as possible, more preferably 0 to 30% by mass, and most preferably none is contained.Examples of the anionic or nonionic surfactant include alkali metal alkyl sulfates such as sodium dodecyl sulfate and potassium dodecyl sulfate; ammonium alkyl sulfates such as ammonium dodecyl sulfate; alkyl sulfonates such as sodium dodecyl polyglycol ether sulfate, sodium sulfocinoate, alkali metal salts of sulfonated paraffin, and ammonium salts of sulfonated paraffin; alkylaryl sulfonates such as sodium laurate, triethanolamine oleate, fatty acid salts of triethanolamine abietate, sodium dodecylbenzenesulfonate, and alkali metal sulfates of alkali phenol hydroxyethylene; higher alkyl naphthalene sulfonates, naphthalene sulfonate-formalin condensates, dialkyl sulfosuccinates, and polyoxyethylene. Examples of surfactants include alkyl sulfate salts, polyoxyethylene alkylaryl sulfate salts, sodium propenyl-2-ethylhexylbenzene sulfosuccinate ester, sulfate esters of (meth)acrylic acid polyoxyethylene, polyoxyethylene alkylpropenyl ether ammonium sulfate, sulfate ester salts such as dodecane-1,2-diol acetate, sulfonates, and carboxylates, polyoxyethylene alkyl ethers, 1,2-dodecanediol ethoxylate, polyoxyethylene alkylaryl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid monoglycerides such as glycerol monolaurate, polyoxyethylene oxypropylene copolymers, and nonionic surfactants such as condensation products of ethylene oxide and fatty acid amines, amides, or acids. Among these, sodium dodecyl polyglycol ether sulfate is preferred from the viewpoint of anti-biofilm effect and emulsion polymerization.

[0027] Examples of the base for forming the neutralized salt of the surfactant [B] include sodium hydroxide, potassium hydroxide, and ammonia, and these may be used alone or in combination of two or more.

[0028] The emulsion-type aqueous anti-biofilm coating agent of the present invention comprises emulsion particles composed of at least a polymer [A] and a surfactant [B], and the particle size must be 50 to 300 nm. It is more preferably 50 to 200 nm. A particle size within the range of 50 to 300 nm provides a good anti-biofilm effect and reduces the amount of coarse particles generated during polymerization. The particle size referred to in the present invention refers to the particle size of the aqueous polymer emulsion contained in the aqueous anti-biofilm coating agent, and refers to the average primary particle size determined by analyzing, using the cumulant method, the autocorrelation function obtained from the time change in scattered light intensity when a sample is irradiated with a laser in measurements using a particle size measurement device based on dynamic light scattering (Zetasizer Nano, manufactured by Malvern Instruments Ltd.). The particle size is measured in a state where the concentration of the aqueous polymer emulsion contained in the aqueous anti-biofilm coating agent is diluted to 0.1% with a 0.001 M potassium chloride aqueous solution, at a temperature of 25°C, without adjusting the pH.

[0029] In the aqueous anti-biofilm coating agent of the present invention, the mass ratio of the polymer [A] having a hydrophobic vinyl monomer structural unit to the surfactant [B] is preferably within the range of [A] / [B] = 100 / 1 to 100 / 10. When [A] / [B] is within the range of 100 / 1 to 100 / 10, the anti-biofilm effect is good.

[0030] The emulsion-type aqueous anti-biofilm coating agent of the present invention preferably contains 50 to 85% by mass of water, and the non-volatile content of the aqueous anti-biofilm coating agent (referring to components other than volatile components such as water; when the coating agent does not contain components other than water, [A], and [B], the non-volatile content is the mass ratio of [A] + [B] to the total amount of the coating agent) is not particularly limited, but is preferably within the range of 15 to 50% by mass from the viewpoint of drying properties.

[0031] The viscosity of the aqueous anti-biofilm coating agent of the present invention (measured at 25°C using a Brookfield viscometer) is not particularly limited, but is preferably 1000 mPa·s or less from the viewpoint of ease of handling.

[0032] The pH of the aqueous anti-biofilm coating agent of the present invention is not particularly limited, but is preferably within the range of 3.0 to 10.0 from the viewpoint of stability.

[0033] The aqueous anti-biofilm coating agent of the present invention can further contain additives as needed. Examples of additives include film-forming aids, thickeners, leveling agents, UV absorbers, UV stabilizers, antioxidants, polymerization inhibitors, fillers, coupling agents, rust inhibitors, dehydrating agents, antibacterial agents, metal deactivators, solvent-based thickeners, solvent-based dispersants, wetting agents, antifoaming agents, reinforcing agents, plasticizers, lubricants, antifogging agents, anticorrosion agents, pigment dispersants, flow adjusters, peroxide decomposers, mold decolorizing agents, fluorescent brighteners, organic flame retardants, inorganic flame retardants, anti-dripping agents, melt flow modifiers, antistatic agents, anti-algae agents, anti-fungal agents, flame retardants, slip agents, metal chelating agents, anti-blocking agents, heat stabilizers, processing stabilizers, colorants, etc. The amount of additives is not particularly limited, but is preferably 5 mass or less relative to the total amount of the coating agent.

[0034] The aqueous anti-biofilm coating agent can be obtained by emulsion polymerization of a monomer mixture in the presence of at least a surfactant [B] and water to form an emulsion containing a polymer [A]. Specifically, a method is employed in which water, the above-mentioned monomers and surfactant, and optionally a chain transfer agent or crosslinker, are charged into a container, and a radical polymerization initiator is added under stirring to allow polymerization to proceed. Alternatively, a method may be employed in which at least water is charged into a container, the temperature is raised to the polymerization initiation temperature with stirring, and then part or all of the water, monomer, surfactant, and radical polymerization initiator are separately added to the container by dropwise or divided addition.

[0035] Suitable radical polymerization initiators include, but are not limited to, persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate; tertiary butyl hydroperoxide; organic peroxides such as benzoyl peroxide and peracetic acid; radical-generating azo compounds such as 2,2'-azobisisobutyronitrile and 2,2'-azobis(2-methylpropionamidine) dihydrochloride; and hydrogen peroxide. Furthermore, a redox initiator may be prepared by using sodium hydrogen sulfite, L-ascorbic acid, ferrous chloride, Rongalit, or the like as a reducing agent.

[0036] The method for producing an emulsion-type aqueous anti-biofilm coating agent of the present invention is characterized by comprising a step of emulsion polymerization of a hydrophobic vinyl monomer containing 30 to 100% by mass of an alkyl(meth)acrylate having 1 to 4 carbon atoms in the presence of a specific surfactant [B] and water. By carrying out production using this method, it is easy to obtain an emulsion having the particle size specified in the present application, and it is also easy to obtain a coating agent with the highest anti-biofilm effect.

[0037] As for the polymerization conditions in the production method of the present invention, the polymerization temperature is preferably 40 to 100° C., more preferably 50 to 90° C., and the polymerization time is preferably 1 to 15 hours.

[0038] The anti-biofilm laminate of the present invention can be obtained by applying an aqueous anti-biofilm coating agent to the surface of a substrate and then forming an anti-biofilm coating layer by heat drying or room temperature drying. The dry film thickness of the anti-biofilm coating layer is not particularly limited as long as it can exhibit an anti-biofilm effect, and can be, for example, about 3 μm to 1 mm.

[0039] Although there are no particular limitations on the substrate that can be used for the anti-biofilm laminate of the present invention, wet area components on which biofilms are likely to form are particularly envisioned, such as resin substrates, metal substrates, etc. Applications of the anti-biofilm laminate include wet area components such as drain plugs, drain traps, drain plates, and drainage pipes in baths, toilets, washbasins, etc., sirocco fans and outdoor unit fins of air conditioners, kitchen range hoods and ventilation fans, etc.

[0040] Examples of resin substrates include polyvinyl chloride, polypropylene, polyethylene, polyethylene terephthalate (PET), polycarbonate, acrylonitrile butadiene styrene (ABS), polypropylene sulfide, and nylon-6.

[0041] Examples of the metal substrate include aluminum, SUS, iron, and copper.

[0042] The method for applying the aqueous anti-biofilm coating agent of the present invention to a substrate is not particularly limited, and examples thereof include immersion coating, brush coating, roll brush coating, spray coating, roll coating, spin coating, dip coating, bar coating, flow coating, electrostatic coating, and die coating.

[0043] The anti-biofilm laminate of the present invention is one comprising an anti-biofilm coating layer obtained by applying at least an aqueous anti-biofilm coating agent to a substrate. The anti-biofilm coating layer needs to be formed on the outermost surface of the substrate. Furthermore, other layers may be present between the anti-biofilm coating layer and the substrate, as long as they do not impair the effects of the present invention. Examples of other layers include a layer formed with a primer paint.

[0044] The bacteria against which the aqueous anti-biofilm coating agent of the present invention exerts an anti-biofilm effect are not particularly limited. Examples of bacteria that are expected to be present in equipment where biofilms occur include gram-negative bacteria such as Pseudomonas aeruginosa (e.g., Pseudomonas aeruginosa), Sphingomonas, Sphingopyxis, Klebsiella, Flavobacterium, Roseomonas, and Brevundimonas, and gram-positive bacteria such as Microbacterium and Staphylococcus.

[0045] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following, "parts" and "%" mean parts by mass and % by mass, respectively, unless otherwise specified.

[0046] The hydrophobic vinyl monomers and their abbreviations used in this example are as follows: [C1-4 alkyl (meth)acrylate [a]] MA: methyl acrylate MMA: methyl methacrylate EA: ethyl acrylate nBA: n-butyl acrylate nBMA: n-butyl methacrylate tBA: t-butyl acrylate [Other hydrophobic vinyl monomers] St: styrene 2EHA: 2-ethylhexyl acrylate 2EHMA: 2-ethylhexyl methacrylate CHMA: cyclohexyl methacrylate VDF: vinylidene fluoride NOAM: N-octylacrylamide [Hydrophilic vinyl monomers] MEA: 2-methoxyethyl acrylate HEMA: 2-hydroxyethyl methacrylate MAAc: sodium methacrylate

[0047] The surfactants [B] (B1 to B12) used in this example and their product names are shown in Table 1.

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] [Synthesis Example 1] A 1-liter four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube was charged with 173.91 parts of methyl methacrylate as a hydrophobic vinyl monomer, 115.94 parts of 2-ethylhexyl acrylate, 10.87 parts of Viewlite ESS (manufactured by Sanyo Chemical Industries, Ltd., active content 40% aqueous solution) as a surfactant [B], 17.39 parts of Sandet EN (manufactured by Sanyo Chemical Industries, Ltd., active content 25% aqueous solution), and 584.39 parts of ion-exchanged water, and the mixture was heated to 60 ° C. under a nitrogen gas atmosphere. Next, 8.70 parts of a 5% aqueous ammonium persulfate solution and 8.70 parts of a 5% aqueous anhydrous sodium bisulfite solution were added to the flask to initiate polymerization. After the start of polymerization, the flask was cooled or heated as appropriate to maintain the temperature inside the flask at 85 ° C. 90 minutes and 150 minutes after the start of polymerization, 5.80 parts of a 5% aqueous ammonium persulfate solution were added to the flask, and the polymerization reaction was continued. 210 minutes after the start of polymerization, 118.01 parts of ion-exchanged water was added, and the flask was further cooled to terminate the polymerization reaction. After that, when the flask reached room temperature, 28% aqueous ammonia was added and the pH was adjusted to 8.0, yielding a sample (X-1) of an aqueous anti-biofilm coating agent with a non-volatile content of 30%. The aqueous anti-biofilm coating agent sample was filtered through a nylon mesh with a mesh size of 150 μm to remove emulsion aggregates. The removed aggregates were dried at 150 °C for 20 minutes and then weighed, and the value calculated using the following formula was used as an index of contamination during production. The contamination (ppm), non-volatile content, Brookfield viscosity, pH, particle size, and Tg of polymer [A] are shown in Table 2. Contaminants (ppm) = 1000 × removed aggregate amount (mg) / [total amount of synthesized aqueous anti-biofilm coating agent (g) × non-volatile content (%)]

[0062] [Synthesis Examples 2 to 26, Comparative Synthesis Examples 1 to 24] Samples (X-2) to (X-50) of aqueous anti-biofilm coating agents were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of monomers and surfactants used were changed as shown in Table 2. The soil content (ppm), non-volatile content, Brookfield viscosity, pH, particle size, and Tg are shown in Tables 2 and 3.

[0063]

[0064]

[0065] <Measurement of particle size> A sample of the aqueous anti-biofilm coating agent was diluted to 0.1% with a 0.001 M aqueous potassium chloride solution, and the particle size was determined by measuring at 25°C using a Zetasizer Nano manufactured by Malvern Instruments Ltd.

[0066] <Anti-biofilm Test> Various aqueous anti-biofilm coating agents were tested to verify their anti-biofilm effects. (1) Preparation of Test Coated Plates (Anti-biofilm Laminates) The aqueous anti-biofilm coating agent was diluted to a concentration of 2% by mass by adding ion-exchanged water. 3 mL of this was placed in the wells of a 24-well cell culture plate (made of polystyrene), and the plate was placed in a circulating thermostatic oven set at 80°C. After 10 hours, the plate was removed from the oven, and a test coated plate with an anti-biofilm coating layer formed inside the wells was obtained. (2) Test Bacteria Pseudomonas aeruginosa was used as the test bacterium. (3) Test Method The test bacterium was a TSB (Triptic Soy Broth, Bacto: Difco Laboratories) medium containing glucose at a final concentration of 1%, and a preculture solution was prepared at 120 rpm. Each preculture solution was diluted with the respective medium to a concentration of 0.1% (v / v), and 1.5 mL was dispensed into a 24-well coated test plate. The test bacteria were cultured at 37°C and 120 rpm for 4 hours to form a biofilm. The culture medium was removed from each well and washed twice with distilled water. 3.0 mL of a crystal violet aqueous solution (0.4 w / v%, 20 w / v% ethanol) was added to the biofilm attached to each well and allowed to stand for 5 minutes for staining. Unbound crystal violet aqueous solution was removed by washing three times with distilled water. 3.0 mL of ethanol was added to each well and allowed to stand for 1 hour to elute the crystal violet from the stained biofilm. The absorbance of the eluate was measured at a wavelength of 595 nm, and the obtained value was taken as the biofilm amount. A lower value indicates a better anti-biofilm effect. The test was performed in an uncoated state, and the absorbance value was 3.41 Abs.

[0067] <Coating Water Resistance Test> 2.0 g of the aqueous anti-biofilm coating agent was added to a precisely weighed shallow metal container and placed in a circulating thermostatic dryer set at 150°C. After 30 minutes, it was removed from the dryer, and the shallow metal container was precisely weighed. 5.0 g of ion-exchanged water was then added to the shallow metal container and allowed to stand overnight. The ion-exchanged water was suctioned and discharged from the shallow metal container, and the container was placed again in the circulating thermostatic dryer set at 150°C. After 30 minutes, it was removed from the dryer and the shallow metal container was precisely weighed. The solubility in water was calculated using the following formula, and the water resistance was evaluated based on the following evaluation criteria. Solubility in water (%) = 100 - [(z-x) / (y-x)] x 100 x: Mass (g) of shallow metal container y: Mass (g) before treatment with ion-exchanged water z: Mass (g) after treatment with ion-exchanged water ○: Solubility in water ≦ 2% ×: Solubility in water < 2%

[0068] [Example 1] An antibiofilm test and a coating film water resistance test were performed on sample (X-1) of the aqueous antibiofilm coating agent using the test methods described above. As a result, the biofilm amount was 1.95 Abs and the coating film water resistance was ○. The results are shown in Table 4.

[0069] [Examples 2 to 26, Comparative Examples 1 to 24] Antibiofilm tests and coating water resistance tests were carried out in the same manner as in Example 1, except that the type of aqueous antibiofilm coating agent used was changed as shown in Table 3. The results are shown in Table 4.

[0070] Comparative Example 25 A sample was prepared by adding Viewlite LCA-25N (manufactured by Sanyo Chemical Industries, Ltd., 28% active ingredient aqueous solution) to the polymer [A] of aqueous anti-biofilm coating agent sample (X-48) to give a concentration of 3 mass %. Except for this, the anti-biofilm test and coating water resistance test were carried out in the same manner as in Example 1. The results are shown in Table 4.

[0071]

[0072] As can be seen from Table 4, the aqueous anti-biofilm coating agent of the present invention described in the examples has a satisfactory level of anti-biofilm effect, superior to the aqueous anti-biofilm coating agents of the comparative examples which do not satisfy any of the configurations or conditions of the present invention.

[0073] A comparison of Example 21, Comparative Example 22, and Comparative Example 25 shows that the aqueous anti-biofilm coating agent in which surfactant [B] satisfying the conditions of the present invention was used during the synthesis of the aqueous polymer emulsion has excellent anti-biofilm effects at a satisfactory level.

[0074] A comparison of Example 8 and Examples 13 to 15 shows that aqueous anti-biofilm coating agents in which the proportion of polyoxyethylene lauryl ether acetic acid or a salt thereof in the surfactant (B) is within the range of 50 to 100 mass % have particularly superior anti-biofilm effects compared to aqueous anti-biofilm coating agents in which this proportion is not the case.

[0075] Comparison of Example 22, Comparative Example 23, and Comparative Example 24 shows that the aqueous anti-biofilm coating agent of the present invention has a superior anti-biofilm effect to the conventional technology described in Patent Document 2.

[0076] A comparison of Example 6 and Comparative Example 3 shows that the aqueous anti-biofilm coating agent of the present invention has a superior anti-biofilm effect to the conventional technology described in Patent Document 3.

Claims

1. An emulsion-type aqueous anti-biofilm coating agent comprising a polymer [A], a surfactant [B] and water, and characterized in that all of the following (1) to (3) are satisfied: (1) The polymer [A] contains 30 to 100 mass% of an alkyl (meth)acrylate [a] having 1 to 4 carbon atoms as a structural unit; (2) The surfactant [B] contains 50 to 100 mass% of at least one selected from the following [b-1] and [b-2] relative to the total amount of [B]: [b-1] Molecular structure: -COOM １ and -CH ２ CH ２ Compound having O- [b-2] molecular structure -COOM １ and -SO ３ M ２ A compound having the formula １ , M. ２ is H, Na, K, NH ４ (3) The emulsion particles are composed of at least a polymer [A] and a surfactant [B], and the particle size is 50 to 300 nm.

2. The emulsion-type aqueous anti-biofilm coating agent according to claim 1, characterized in that the mass ratio of the polymer [A] and the surfactant [B] is [A] / [B]=100 / 1-10.

3. The emulsion-type aqueous anti-biofilm coating agent according to claim 1, characterized in that the surfactant [B] contains 50 to 100 mass% of polyoxyethylene lauryl ether acetic acid or a salt thereof relative to the total amount of [B].

4. A method for producing an emulsion-type aqueous anti-biofilm coating agent containing a polymer [A] by emulsion polymerization of a monomer mixture in the presence of a surfactant [B] and water, characterized in that the monomer mixture contains 30 to 100 mass% of an alkyl (meth)acrylate [a] having 1 to 4 carbon atoms, and the surfactant [B] contains at least one selected from the following [b-1] and [b-2] in 50 to 100 mass% relative to the total amount of [B]. [b-1] A molecular structure of -COOM １ and -CH ２ CH ２ Compound having O- [b-2] molecular structure -COOM １ and -SO ３ M ２ A compound having the formula １ , M. ２ is H, Na, K, NH ４ (represents one or more of the following) 5. An anti-biofilm laminate having a layer of the emulsion-type aqueous anti-biofilm coating agent described in any one of claims 1 to 3 on the surface of a substrate.

6. A method for producing an anti-biofilm laminate, comprising the step of applying an emulsion-type aqueous anti-biofilm coating agent according to any one of claims 1 to 3 to a surface of a substrate.

Images