JP7728212B2 - Paint and paint manufacturing method - Google Patents

Description

The present invention relates to a paint and a method for producing a paint.

Conventionally, building materials, vehicle interior materials, furniture materials, packaging materials, and the like have been coated with paint to improve aesthetics and provide protection. In recent years, however, from the perspectives of environmental issues and safety, there has been a demand for water-based paints that minimize the use of organic solvents. Furthermore, polyurethane resins are widely used as binders for water-based paints, due to their excellent physical properties, such as abrasion resistance and flex resistance, as well as their appearance, which includes texture and a luxurious feel.

For example, Patent Document 1 discloses a paint containing a siloxane-modified urethane resin, polyurethane gel particles, and a crosslinker as a paint for the surface layer of synthetic imitation leather (a general term for artificial leather and synthetic leather). Patent Document 2 discloses a matte paint containing a polyurethane urea aqueous dispersion, which is the reaction product of a polymer polyol, a compound having one or more active hydrogen atoms and a hydrophilic group in its molecule, a dihydric alcohol, a polyisocyanate, and a polyamine having two primary amino groups and one or more secondary amino groups. Patent Document 3 also discloses a matte paint containing a polyurethane urea aqueous dispersion, which is the reaction product of a polyol component including a polymer polyol, a compound having one or more active hydrogen atoms and a hydrophilic group in its molecule, a dihydric alcohol, and a trihydric or higher alcohol, a polyisocyanate, and a polyamine having two primary amino groups and one or more secondary amino groups, and which has an acid value of 1 to 16 mgKOH/g converted to solids.

JP 2009-001713 A Japanese Patent Application Laid-Open No. 2019-011408 Japanese Patent Application Laid-Open No. 2020-097707

On the other hand, in addition to increased awareness of hygiene in living environments, the global spread of COVID-19 has also been a major factor, resulting in a rapidly increasing demand for antibacterial treatment of various items surrounding living environments, such as wallpaper, doorknobs, handles, instrument panels, tables, and sofas.

An antibacterial agent can be blended into paint to impart antibacterial properties to the coating film. However, as a result of the inventor's research, it was found that blending a silver-based inorganic antibacterial agent, which is widely used as an antibacterial agent, into a coating that uses an aqueous dispersion of a polyurethane resin reduces the coating's suitability, as the silver-based inorganic antibacterial agent tends to settle. In coatings where the antibacterial agent tends to settle and has low dispersibility, there is a risk of uneven antibacterial properties in the coating film.

The present invention therefore aims to provide a paint that uses an aqueous dispersion of a polyurethane resin, which has good paint suitability and is capable of forming a coating film with good antibacterial properties.

The present invention provides a coating material containing an aqueous dispersion of a polyurethane resin and an antibacterial agent, wherein the polyurethane resin includes a polyurethane resin (A) having a silanol group, and the antibacterial agent includes a silane compound (B) having a quaternary ammonium salt structure and a silanol group.

The present invention provides a paint that uses an aqueous dispersion of a polyurethane resin, which has good paint suitability and is capable of forming a coating film with good antibacterial properties.

The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments.

<Paint>
A paint according to one embodiment of the present invention (hereinafter sometimes simply referred to as the "paint" or "paint of this embodiment") contains an aqueous dispersion of a polyurethane resin and an antibacterial agent. The polyurethane resin includes a polyurethane resin (A) having silanol groups (hereinafter sometimes simply referred to as the "polyurethane resin (A)" or the "silanol group-containing polyurethane resin (A)"). The antibacterial agent includes a silane compound (B) having a quaternary ammonium salt structure and silanol groups (hereinafter sometimes simply referred to as the "silane compound (B)" or the "quaternary ammonium salt-containing silane compound (B)"). In this specification, the term "silanol group" also includes groups that generate silanol groups upon hydrolysis.

The paint of this embodiment contains an aqueous dispersion of a silanol group-containing polyurethane resin (A) and a quaternary ammonium salt-containing silane compound (B), which is an antibacterial agent, and therefore has good paint suitability and is capable of forming a coating film with good antibacterial properties. Specifically, it exhibits good paint suitability, such as good dispersibility and resistance to sedimentation of the polyurethane resin (A) and the antibacterial agent (silane compound (B)), while also being capable of forming a coating film with good antibacterial properties.

In one aspect of the paint of this embodiment, the silane compound (B) can be incorporated separately from the polyurethane resin (A), i.e., chemically unbound. In this case, because both the polyurethane resin (A) and the silane compound (B) contain silanol groups, a condensation reaction between the polyurethane resin (A) and the silane compound (B) can occur during the formation of a coating film from a paint containing them separately. Furthermore, in one aspect of the paint of this embodiment, the silane compound (B) can be incorporated integrally with the polyurethane resin (A), i.e., chemically bound, as a condensation reaction product of the silanol groups present in the polyurethane resin (A) and the silane compound (B). In either of the above aspects, the antibacterial agent, the quaternary ammonium salt-containing silane compound (B), can be immobilized to the polyurethane resin (A) in the coating film formed from the paint, thereby providing abrasion resistance comparable to that of a paint containing no antibacterial agent, and thereby providing sustained antibacterial properties.

The following describes in detail each component of the paint of this embodiment, including preferred compositions from the perspective of making it easier to obtain the desired paint.

[Water dispersion of polyurethane resin (A)]
The coating material of this embodiment contains an aqueous dispersion of a polyurethane resin (A) having silanol groups (silanol group-containing polyurethane resin (A)). The coating material of this embodiment may contain an aqueous dispersion of a polyurethane resin other than the aqueous dispersion of the polyurethane resin (A), provided that the purpose of the coating material is not impaired. In this specification, "polyurethane resin" is a general term for polyurethane resins, polyurea resins, and polyurethane-urea resins.

The silanol group-containing polyurethane resin (A) can be obtained by reacting a urethane prepolymer having an isocyanate group (hereinafter sometimes referred to as "NCO group") with an amine compound containing a compound (f) having an amino group and an alkoxysilyl group. In other words, the reaction product can be used as the silanol group-containing polyurethane resin (A). The NCO group-containing urethane prepolymer can be obtained by reacting reaction components including a compound (a) having an anionic hydrophilic group other than a hydroxyl group and an active hydrogen-containing group other than the anionic hydrophilic group, at least one compound (b) selected from the group consisting of a polyol and a polyamine, and a polyisocyanate (e). In other words, the reaction product can be used as the NCO group-containing urethane prepolymer.

The above-mentioned urethane-based prepolymer having an NCO group is preferably one obtained by further using a chain extender (c) and a polysiloxane (d) having an active hydrogen-containing group in addition to the above-mentioned compound (a), compound (b), and polyisocyanate (e). That is, the above-mentioned urethane-based prepolymer having an NCO group is preferably a reaction product of compound (a), compound (b), chain extender (c), polysiloxane (d) having an active hydrogen-containing group, and polyisocyanate (e). In this case, it is more preferable to use at least a polycarbonate polyol (b1) as compound (b), and it is more preferable to use at least a dihydric alcohol as chain extender (c).

In this specification, "active hydrogen-containing groups other than anionic hydrophilic groups" refers to functional groups containing active hydrogen that are reactive with isocyanate groups, excluding anionic hydrophilic groups. Specific examples of such "active hydrogen-containing groups" include hydroxyl groups, mercapto groups, and amino groups.

(Compound (a))
Compound (a) having an anionic hydrophilic group other than a hydroxyl group and an active hydrogen-containing group other than the anionic hydrophilic group (hereinafter, sometimes simply referred to as "compound (a)") is preferably used as a component that imparts water dispersibility to polyurethane resin (A). By using compound (a) as a raw material for polyurethane resin (A), polyurethane resin (A) having an anionic hydrophilic group introduced therein can be obtained. This allows polyurethane resin (A) to be stably dispersed in water without the use of an emulsifier (surfactant), and the coating material of this embodiment can be prepared as an aqueous coating material.

In compound (a), the active hydrogen refers to a hydrogen atom that reacts with the isocyanate group of the polyisocyanate, and examples thereof include hydrogen atoms of hydroxyl groups, mercapto groups, and amino groups. Of these, the hydrogen atom of a hydroxyl group is preferred. Furthermore, in compound (a), the anionic hydrophilic group refers to an anionic group that exhibits affinity with water and can ionize in water to generate an anion. Examples of anionic hydrophilic groups other than hydroxyl groups include carboxy groups, sulfo groups, and phosphate groups. Of these, the carboxy group is preferred. The anionic hydrophilic group may be neutralized in whole or in part.

Examples of compound (a) include carboxylic acid compounds such as 2,2-bis(hydroxymethyl)propionic acid (also known as dimethylolpropionic acid), 2,2-bis(hydroxymethyl)butyric acid (also known as dimethylolbutanoic acid), lactic acid, and glycine; and sulfonic acid compounds such as 2-aminoethanesulfonic acid (also known as taurine) and sulfoisophthalic acid-based polyester diols. One or more of these compounds can be used. Among these, carboxylic acid compounds of dihydric alcohols are preferred from the standpoints of ease of availability and ease of adjusting the acid value, and dimethylolalkanoic acids such as dimethylolpropionic acid and dimethylolbutanoic acid are more preferred.

The anionic hydrophilic groups may be neutralized in whole or in part with a neutralizing agent. The anionic hydrophilic groups in compound (a) may be neutralized to form a salt-type compound (a) having the neutralized anionic hydrophilic groups. Alternatively, the anionic hydrophilic groups introduced into polyurethane resin (A) may be neutralized to form a salt-type polyurethane resin (A). Examples of neutralizing agents include alkylamines such as ethylamine, trimethylamine, triethylamine, triisopropylamine, and tributylamine; alkanolamines such as triethanolamine, N-methyldiethanolamine, N-phenyldiethanolamine, monoethanolamine, dimethylethanolamine, diethylethanolamine, and 2-amino-2-ethyl-1-propanol; and alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide. Among these, tertiary alkylamines such as triethylamine, tertiary alkanolamines such as dimethylaminoethanol, and sodium hydroxide are preferred.

The content (amount used) of compound (a) in the reaction components can be set from the viewpoint of achieving both water dispersibility and water resistance in the resulting polyurethane resin (A). Specifically, the content (amount used) of compound (a) in the reaction components is preferably an amount that results in an acid value of the resulting polyurethane resin (A) of 2 to 200 mgKOH/g, and more preferably an amount that results in an acid value of 5 to 100 mgKOH/g.

(Compound (b))
At least one compound (b) selected from the group consisting of polyols and polyamines (hereinafter, sometimes simply referred to as "compound (b)") is a component that can constitute the main skeleton of polyurethane resin (A). Since polyols and/or polyamines are used as compound (b), hereinafter, compound (b) may be referred to as "polyol (b),""polyamine(b)," or "polyol and/or polyamine (b)." Of the compounds (b), it is preferable to use at least polyol (b).

Polyol (b) is a compound having two or more hydroxyl groups per molecule. One or more of the conventional polyols used in urethane synthesis can be used as polyol (b). Examples of polyol (b) include polyols with a number average molecular weight (Mn; determined by terminal functional group quantification) of 500 or more, as well as short-chain diols and trihydric or higher polyhydric alcohols suitable as chain extenders (c), which will be described later.

Among polyols (b), polyols having an Mn of 500 or more as determined by terminal functional group quantification are preferred, and specific examples thereof include polyester polyols, polyether polyols, polycarbonate polyols, and other polyols. Of these, polycarbonate polyols (sometimes referred to as "polycarbonate polyol (b1)" in this specification) are more preferred.

Polyester polyols include those obtained by condensation polymerization of aliphatic dicarboxylic acids (e.g., succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid, etc.) and/or aromatic dicarboxylic acids (e.g., isophthalic acid, terephthalic acid, etc.) with low molecular weight glycols (e.g., ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, etc.).

Specific examples of such polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene/butylene adipate diol, polyneopentyl/hexyl adipate diol, poly-3-methylpentane adipate diol, polybutylene isophthalate diol, polycaprolactone diol, and poly-3-methylvalerolactone diol.

Specific examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random/block copolymers thereof.

Specific examples of polycarbonate polyols include polytetramethylene carbonate diol, polypentamethylene carbonate diol, polyneopentyl carbonate diol, polyhexamethylene carbonate diol, poly(1,4-cyclohexanedimethylene carbonate) diol, and random/block copolymers thereof.

Specific examples of other polyols include dimer diol, polybutadiene polyol and its hydrogenated products, polyisoprene polyol and its hydrogenated products, polylactone polyol, acrylic polyol, epoxy polyol, polyether ester polyol, siloxane-modified polyol, α,ω-polymethyl methacrylate diol, and α,ω-polybutyl methacrylate diol.

The number-average molecular weight (Mn; determined by terminal functional group quantification) of polyol (b) is not particularly limited, but is preferably 500 to 3,000. When the Mn of polyol (b) is 3,000 or less, the cohesive strength of the urethane bonds is more likely to be expressed, tending to improve mechanical properties. Furthermore, crystalline polyols with an Mn of 3,000 or less are less likely to cause whitening when formed into a film.

Polyamine (b) is a compound having two or more amino groups per molecule. Polyamine (b) is a component that can form the main skeleton of polyurethane resin (A) either alone or in combination with the above-mentioned polyol (b). Examples of polyamine (b) include polyamines with a number-average molecular weight (Mn; determined by terminal functional group quantification) of 500 or more, and short-chain diamines suitable as chain extenders (c) described below. One or more types of polyamine (b) can be used. Among these, polyamines (b) with an Mn of 500 or more are preferred, and specific examples include long-chain alkylenediamines, polyoxyalkylenediamines, terminal amine polyamides, and siloxane-modified polyamines.

(Chain extender (c))
Examples of the chain extender (c) that can be used in the synthesis of the urethane-based prepolymer having an NCO group include short-chain diols (dihydric alcohols), trihydric or higher polyhydric alcohols, and short-chain diamines. One or more types of chain extender (c) can be used. Among the chain extenders (c), it is preferable to use at least a short-chain diol.

The short-chain diol that can be used as the chain extender (c) is a diol compound with a number average molecular weight (Mn) of less than 500. The number average molecular weight of a short-chain diol is the arithmetic mean value of the molecular weight calculated from the formula weight. Examples of short-chain diols include aliphatic glycols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, and neopentyl glycol, and their low molar alkylene oxide adducts (Mn less than 500); alicyclic glycols such as 1,4-bishydroxymethylcyclohexane and 2-methyl-1,1-cyclohexanedimethanol, and their low molar alkylene oxide adducts (Mn less than 500); aromatic glycols such as xylylene glycol and their low molar alkylene oxide adducts (Mn less than 500); bisphenols such as bisphenol A, thiobisphenol, and sulfonebisphenol, and their low molar alkylene oxide adducts (Mn less than 500); and alkyldialkanolamines such as alkyldiethanolamines having an alkyl group of 1 to 18 carbon atoms. One or more short-chain diols can be used.

Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and tris-(2-hydroxyethyl)isocyanurate. One or more trihydric or higher polyhydric alcohols can be used.

Short-chain diamines that can be used as chain extenders (c) are diamine compounds with a number average molecular weight (Mn) of less than 500. The number average molecular weight of a short-chain diamine is the arithmetic mean value of the molecular weight calculated from the formula weight. Examples of short-chain diamines include aliphatic diamine compounds such as ethylenediamine, trimethylenediamine, hexamethylenediamine, and octamethylenediamine; aromatic diamine compounds such as phenylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(phenylamine), 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl sulfone; alicyclic diamine compounds such as cyclopentanediamine, cyclohexyldiamine, 4,4-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, and isophoronediamine; and hydrazines such as hydrazine, carbodihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, and phthalic acid dihydrazide. One or more types of short-chain diamines can be used.

(Polysiloxane (d) having an active hydrogen-containing group)
In the synthesis of a urethane-based prepolymer having an NCO group, a polysiloxane (d) having at least one active hydrogen-containing group per molecule may be used. The polysiloxane (d) having an active hydrogen-containing group can be used when the polyurethane-based resin (A) is polysiloxane-modified. By using the polysiloxane (d) in the synthesis of the polyurethane-based resin (A), a polysiloxane segment can be contained in the polyurethane-based resin (A). This polysiloxane segment is contained in the main chain of the polyurethane-based resin (A) or in a branched state. By modifying the polyurethane-based resin (A) with polysiloxane, improvements in the scratch resistance and contamination resistance of the coating film can be expected.

Examples of polysiloxanes (d) having active hydrogen-containing groups include amino-modified polysiloxanes, epoxy-modified polysiloxanes, alcohol-modified polysiloxanes, and mercapto-modified polysiloxanes. One or more of these can be used. Epoxy-modified polysiloxanes are polysiloxanes that have been epoxy-modified using active hydrogen-containing groups. However, because they can react with the isocyanate groups of polyisocyanates to form the backbone of polyurethane resin (A), they are included in polysiloxanes having at least one active hydrogen-containing group.

Examples of amino-modified polysiloxanes include compounds represented by the following general formulas (1) to (6):

Examples of epoxy-modified polysiloxanes include compounds represented by the following general formulas (7) to (12). The epoxy compounds represented by the following general formulas (7) to (12) can also be reacted with polyols, polyamides, polycarboxylic acids, or the like to have active hydrogen-containing groups at their terminals.

Examples of alcohol-modified polysiloxanes include compounds represented by the following general formulas (13) to (19):

Examples of mercapto-modified polysiloxanes include compounds represented by the following general formulas (20) to (23):

The polysiloxanes (d) having at least one active hydrogen-containing group listed above are preferred compounds for use as raw materials for polyurethane resin (A), but are not limited to the specific examples listed above. Therefore, in addition to the specific examples listed above, other currently commercially available compounds and compounds that are easily available on the market can also be used as polysiloxanes (d) having at least one active hydrogen-containing group. Among polysiloxanes (d) having at least one active hydrogen-containing group, alcohol-modified polysiloxanes are preferred, and alcohol-modified polysiloxanes having two hydroxyl groups are more preferred.

(Polyisocyanate (e))
The polyisocyanate (e) is a compound having two or more isocyanate groups in one molecule. As the polyisocyanate (e), any of those conventionally used in the production of polyurethanes can be used, and one or more kinds of polyisocyanates can be used without any particular limitation.

Specific examples of polyisocyanates (e) include aromatic diisocyanates such as tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, and 4,4'-diisocyanate dibenzyl; methylene diisocyanate, 1,4-tetramethylene diisocyanate, and 1,6-hexamethylene diisocyanate. Examples of suitable diisocyanates include aliphatic diisocyanates such as 1,4-cyclohexylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, hydrogenated MDI, and hydrogenated XDI; isocyanate prepolymers such as adducts of various diisocyanates, isocyanurates of various diisocyanates, biurets of HDI, and allophanates of HDI; and prepolymers having isocyanate groups at the ends obtained by reacting various diisocyanates with low-molecular-weight polyols and/or polyamines so that the ends are isocyanate.

(Compound (f))
A urethane prepolymer having an NCO group can be obtained by reacting the above-mentioned compound (a), compound (b), and polyisocyanate (e), and, if necessary, a chain extender (c) and a polysiloxane (d) as reaction components. The polyurethane resin (A) can be obtained by reacting this urethane prepolymer having an NCO group with an amine compound containing a compound (f) having an amino group and an alkoxysilyl group (hereinafter, sometimes simply referred to as "compound (f)" or "amino group-containing silane compound (f)"). The amine compound used in this reaction acts as a chain extender (second chain extender) for the urethane prepolymer having an NCO group. By using at least compound (f) as the amine compound, alkoxysilyl groups, which generate silanol groups upon hydrolysis, are introduced into the polyurethane resin (A). Note that other amine compounds (e.g., the above-mentioned short-chain diamines) may be used in combination with the amino group-containing silane compound (f).

Examples of compound (f) include N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. It is preferable to use at least one of these. Of these, compound (f) having one primary amino group and one secondary amino group per molecule is more preferred. Of these, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane are even more preferred, considering their compatibility with the reactive groups of the quaternary ammonium salt-containing silane compound (B) used as the antibacterial agent.

When synthesizing a urethane-based prepolymer having an NCO group, the molar ratio (a/b) of compound (a) to compound (b) is preferably 0.05 to 2.0.

Furthermore, when synthesizing a urethane-based prepolymer having NCO groups, the equivalent ratio (NCO/active hydrogen) of the isocyanate groups of the polyisocyanate (e) to the total active hydrogen-containing groups of compound (a), compound (b), and the chain extender (c) and polysiloxane (d) used as needed is preferably 1.1 to 5.0, more preferably 1.1 to 3.0, and even more preferably 1.2 to 1.8. By ensuring that the equivalent ratio (NCO/active hydrogen) is 1.1 or higher, it is possible to convert the molecular terminals of the resulting urethane-based prepolymer to NCO groups. Furthermore, by ensuring that the equivalent ratio (NCO/active hydrogen) is 5.0 or lower, it is possible to prevent more unreacted polyisocyanate (e) from remaining in the reaction system than necessary. In a preferred embodiment, the above equivalent ratio (NCO/active hydrogen) represents the equivalent ratio (NCO/OH) of the isocyanate groups of polyisocyanate (e) to the total hydroxyl groups of compounds (a) to (d).

When synthesizing polyurethane resin (A), the equivalent ratio (amino groups/NCO) of the amino groups (total of primary and secondary amino groups) possessed by the amine compound containing amino group-containing silane compound (f) to the NCO groups of the urethane prepolymer having NCO groups is preferably 0.001 to 1.0, more preferably 0.01 to 0.6. It is even more preferable that amino group-containing silane compound (f) be used so that the measured NCO % of the urethane prepolymer having NCO groups is 5 to 15%.

[Method of producing aqueous dispersion of polyurethane resin (A)]
The aqueous dispersion of polyurethane resin (A) can be produced by following known methods for producing polyurethane resins. For example, first, in the presence of an organic solvent not containing active hydrogen in the molecule, or in the absence of an organic solvent, reaction components including compound (a), compound (b), and polyisocyanate (e), and optionally chain extender (c) and polysiloxane (d), are reacted by a one-shot method or a multi-stage method at 20 to 150°C, preferably 60 to 110°C, until the reaction product reaches, for example, a theoretical NCO % to obtain a urethane prepolymer having NCO groups. The blending ratio of the reaction components may be such that a urethane prepolymer having NCO groups at its terminals is formed. In one embodiment, the compound (a) can be preferably 0.1 to 30 mass %, more preferably 5 to 20 mass %, the compound (b) can be preferably 20 to 90 mass %, more preferably 50 to 85 mass %, and the polysiloxane (d) can be preferably 0.01 to 50 mass %, more preferably 1 to 20 mass %, based on the mass of the total solid content of the reaction components.

Next, the resulting urethane prepolymer having NCO groups is emulsified with water and a neutralizing agent, and then an amino group-containing silane compound (f) and, if necessary, other amine compounds are added to cause a chain extension reaction of the urethane prepolymer having NCO groups to form urea bonds. After that, the solvent is removed as necessary, and an aqueous dispersion of polyurethane resin (A) can be obtained. Furthermore, as described below, after the chain extension reaction to form the urea bonds, a quaternary ammonium salt-containing silane compound (B), which is an antibacterial agent, may be added to carry out hydrolysis and condensation reactions.

The weight-average molecular weight (Mw) of the polyurethane resin (A) obtained as described above is preferably 1,000 to 500,000, as this allows properties such as flexibility, adhesion, and abrasion resistance to be more effectively exhibited.

In addition, a catalyst can be used, if necessary, in the synthesis of the polyurethane resin (A) described above. Examples of catalysts include salts of metals with organic and inorganic acids, such as dibutyltin laurate, dioctyltin laurate, stannous octoate, zinc octoate, and tetra-n-butyl titanate, as well as organometallic derivatives, organic amines such as triethylamine, and diazabicycloundecene-based catalysts.

Furthermore, as mentioned above, polyurethane resin (A) may be synthesized without solvent, or, if necessary, using an organic solvent. Suitable organic solvents include those that are inactive toward isocyanate groups or that are less active than the reaction components. Examples of the solvent include ketone solvents (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), aromatic hydrocarbon solvents (toluene, xylene, Swazol (an aromatic hydrocarbon solvent manufactured by Cosmo Oil Co., Ltd.), Solvesso (an aromatic hydrocarbon solvent manufactured by Exxon Chemical Co., Ltd.), etc.), aliphatic hydrocarbon solvents (n-hexane, etc.), alcohol solvents (methanol, ethanol, isopropanol, etc.), ether solvents (dioxane, tetrahydrofuran, etc.), ester solvents (ethyl acetate, butyl acetate, isobutyl acetate, etc.), glycol ether ester solvents (ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate, etc.), amide solvents (dimethylformamide, dimethylacetamide, etc.), and lactam solvents (n-methyl-2-pyrrolidone, etc.). Of these, methyl ethyl ketone, ethyl acetate, acetone, and tetrahydrofuran are preferred, taking into consideration solvent recovery, solubility during urethane synthesis, reactivity, boiling point, and emulsifiable dispersibility in water.

[Antibacterial Agents]
The coating material of this embodiment contains a silane compound (B) having a quaternary ammonium salt structure and a silanol group as an antibacterial agent. The coating material may contain an antibacterial agent other than the quaternary ammonium salt-containing silane compound (B) within the scope of the present invention.

In one embodiment of the paint, the quaternary ammonium salt-containing silane compound (B) can be contained in a chemically unbonded (unreacted) state with the polyurethane resin (A). In this case, because both the polyurethane resin (A) and the quaternary ammonium salt-containing silane compound (B) contain silanol groups, they can undergo a condensation reaction during the formation of a paint film containing them separately (e.g., between application and drying of the paint). In another embodiment of the paint, the quaternary ammonium salt-containing silane compound (B) and the polyurethane resin (A) can be contained in a chemically bonded state as a condensation reaction product of their silanol groups. In this way, the polyurethane resin (A) and the quaternary ammonium salt-containing silane compound (B) can be condensed in advance or during the formation of the paint film, thereby immobilizing the antibacterial agent, the quaternary ammonium salt-containing silane compound (B), to the polyurethane resin (A) in the paint film. As a result, the coating film can be expected to have a level of abrasion resistance comparable to that of a coating film containing no antibacterial agent, and therefore, long-lasting antibacterial properties can also be expected. Furthermore, from the standpoints of ease of production and storage stability (maintaining the dispersibility of the matting agent when prepared as a matte paint), the embodiment in which the polyurethane resin (A) and compound (B) are condensed during coating film formation is preferable to the embodiment in which they are incorporated in advance in a chemically bonded state.

The paint of this embodiment contains an aqueous dispersion of the aforementioned polyurethane resin (A). In this specification, the silanol groups possessed by the quaternary ammonium salt-containing silane compound (B) are considered to include groups that generate silanol groups upon hydrolysis. If we distinguish between silanol groups (-SiOH) and groups that generate silanol groups (-SiOH) upon hydrolysis, the quaternary ammonium salt-containing silane compound (B) must contain at least one of a silanol group and a group that generates a silanol group upon hydrolysis.

Groups that generate silanol groups upon hydrolysis are silicon-bonded groups, such as alkoxy groups, acyloxy groups, alkenyloxy groups, and alkoxy-substituted alkoxy groups. Among these, alkoxy groups bonded to silicon atoms (alkoxysilyl groups including the silicon atom) are preferred. The alkoxy group preferably contains 1 to 4 carbon atoms, more preferably 1 to 3. Preferred alkoxy groups include methoxy, ethoxy, n-propoxy, and isopropoxy.

The quaternary ammonium salt structure in the quaternary ammonium salt-containing silane compound (B) preferably has three or four hydrocarbon groups (such as alkyl groups and alkylene groups) bonded to the quaternary ammonium cation. It is more preferable that the total number of carbon atoms in the hydrocarbon groups bonded to the quaternary ammonium cation is 1 to 30.

The quaternary ammonium salt-containing silane compound (B) preferably has a siloxane bond (-Si-O-Si-) containing a silicon atom in the silanol group (-SiOH). The number of quaternary ammonium salt structures per molecule of the quaternary ammonium salt-containing silane compound (B) is preferably 1 or 2. Furthermore, the number of silanol groups per molecule of the quaternary ammonium salt-containing silane compound (B) is preferably 1 to 4, more preferably 2 to 4, and even more preferably 3 or 4.

As the quaternary ammonium salt-containing silane compound (B), commercially available products can be used due to their ease of availability. For example, examples of commercially available quaternary ammonium salt-containing silane compounds (B) that have a siloxane bond, two quaternary ammonium salt structures (quaternary ammonium cations), and four silanol groups in one molecule include the product names "X-12-1126" and "X-12-1139" (both manufactured by Shin-Etsu Chemical Co., Ltd.). Furthermore, examples of commercially available quaternary ammonium salt-containing silane compounds (B) having one quaternary ammonium salt structure (quaternary ammonium cation) and three alkoxy groups (groups that generate silanol groups upon hydrolysis) per molecule include products under the trade name "KBM-9418-40" (manufactured by Shin-Etsu Chemical Co., Ltd.), the trade name "Nikkanon RB-40" (manufactured by Nicca Chemical Co., Ltd.), and the trade name "SANITIZED T99-19" (manufactured by SANITIZED AG).

The content of the quaternary ammonium salt-containing silane compound (B) is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the polyurethane resin (A).

[Crosslinking agent]
The coating material of this embodiment preferably further contains a crosslinking agent. The crosslinking agent more preferably contains at least one selected from the group consisting of an isocyanate-based crosslinking agent (including a blocked isocyanate-based crosslinking agent), a carbodiimide-based crosslinking agent, an oxazoline-based crosslinking agent, an epoxy-based crosslinking agent, and a metal complex-based crosslinking agent. Among these, a crosslinking agent capable of reacting with a carboxy group and/or a silanol group present in the molecule of the polyurethane-based resin (A) or a silanol group and/or a quaternary ammonium cation present in the antibacterial agent is preferred, and for example, a carbodiimide-based crosslinking agent is more preferred.

Commercially available crosslinking agents are preferably used due to their ease of availability. Examples of commercially available isocyanate crosslinking agents include the "Duranate" series (manufactured by Asahi Kasei Corporation) and the "Aquanate" series (manufactured by Tosoh Corporation). Examples of commercially available epoxy crosslinking agents include the "jER Cure" series (manufactured by Mitsubishi Chemical Corporation). Examples of commercially available carbodiimide crosslinking agents include the "Carbodilite" series (manufactured by Nisshinbo Chemical Inc.). Examples of commercially available oxazoline crosslinking agents include the "Epocross" series (manufactured by Nippon Shokubai Co., Ltd.). Commercially available metal complex crosslinking agents include, for example, the "Orgatix TC" series of organic titanium chelate compounds, the "Orgatix ZC" series of organic zirconium chelate compounds, and the "Orgatix Al" series of organic aluminum chelate compounds (all manufactured by Matsumoto Fine Chemical Co., Ltd.), as well as the "Nasem" series of acetylacetone metal complexes of metals such as aluminum, chromium, cobalt, copper, iron, nickel, vanadium, and zinc (manufactured by Nippon Chemical Industry Co., Ltd.).

Using an appropriate amount of crosslinking agent is effective in improving the durability, heat resistance, and light resistance of the coating film. From this perspective, the content of crosslinking agent in the coating is preferably 40 parts by mass or less, more preferably 0.5 to 30 parts by mass, and even more preferably 0.5 to 20 parts by mass, calculated as solids per 100 parts by mass of polyurethane resin (A).

[Matting agent]
The paint of this embodiment may further contain a matting agent. By including a matting agent, it is possible to prepare a matte paint. Both organic particles and inorganic particles can be used as the matting agent. Specific examples of matting agents include silica particles, silicone resin particles, fluorine-based resin particles, acrylic resin particles, polyurethane gel particles, silicone-modified polyurethane gel particles, polyethylene particles, and reactive siloxanes. One or more of these can be used. Furthermore, when a matting agent is used, a dispersant for dispersing the matting agent may be used in combination.

The paint of this embodiment preferably contains at least one matting agent selected from the group consisting of polyurethane gel particles and silica particles, and more preferably contains both polyurethane gel particles and silica particles as the matting agent. By using this specific matting agent in combination with the specific antibacterial agent described above, it becomes easier to obtain a matte paint that combines the properties required of an aqueous matte paint (e.g., dispersibility, anti-settling properties, matte properties (60° gloss value), adhesion to substrates, vacuum formability, stain resistance, abrasion resistance, flex resistance, light resistance, heat resistance, etc.).

(Polyurethane gel particles)
Polyurethane gel particles can be easily obtained by emulsion polymerization or the like, and commercially available products can also be used. Examples of commercially available polyurethane gel particles include those under the trade name "Art Pearl" (manufactured by Negami Chemical Industrial Co., Ltd.). The polyurethane gel particles are preferably spherical and have a volume average particle diameter of approximately 0.1 to 30.0 μm. The volume average particle diameter in this specification can be determined from the 50% cumulative average value measured using a dynamic light scattering particle size distribution analyzer (trade name "Microtrac UPA", manufactured by Nikkiso Co., Ltd.).

The content of polyurethane gel particles is preferably 3 to 100 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, per 100 parts by mass of polyurethane resin (A).

(Silica particles)
The silica particles can be either natural or synthetic. Examples of synthetic silica particles include precipitated silica, gel silica, and dry silica. Of these, precipitated silica and dry silica are preferred. As long as the volume average particle diameter of the silica particles is approximately 0.5 to 15.0 μm, amorphous or porous particles with an irregular surface can be used. The use of such silica particles facilitates reaction with the silanol groups present in the molecules of the polyurethane resin (A), making it possible to form a coating film with even improved durability.

The content of silica particles is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 10 parts by mass, per 100 parts by mass of polyurethane resin (A).

[Liquid medium]
The paint of this embodiment contains the aqueous dispersion of the polyurethane resin described above, and therefore contains water, and can therefore be prepared as an aqueous paint. Ion-exchanged water is preferably used as the water. Furthermore, the paint can contain a liquid medium other than water, as necessary. A water-soluble organic solvent is preferred as the liquid medium. Examples of water-soluble organic solvents include methanol, ethanol, 1-propanol, isopropanol, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether. One or more water-soluble organic solvents can be used.

The content of the liquid medium, including water and water-soluble organic solvents, in the paint is preferably 5 to 99% by mass, more preferably 30 to 90% by mass, and even more preferably 40 to 90% by mass, based on the total mass of the paint. On the other hand, the solids concentration of the paint is preferably 1 to 95% by mass, more preferably 10 to 70% by mass, and even more preferably 10 to 60% by mass, based on the total mass of the paint.

[Other additives]
The coating material may contain conventionally known resins and various additives as long as they do not interfere with the objectives of the present invention. Examples of additives include antioxidants (hindered phenols, phosphites, thioethers, etc.), light stabilizers (hindered amines, etc.), UV absorbers (benzophenones, benzotriazoles, etc.), gas discoloration stabilizers (hydrazines, etc.), hydrolysis inhibitors (carbodiimides, etc.), metal deactivators (hydrazines, etc.), antifungals, preservatives, flame retardants, lubricants, slip agents, leveling agents, thickeners, antifoaming agents, dispersants, emulsifiers, surfactants, pigments, and colorants. One or more of these additives may be used.

<Paint manufacturing method>
The coating material of this embodiment can be produced by mixing an aqueous dispersion of a polyurethane resin (A), a quaternary ammonium salt-containing silane compound (B), a crosslinking agent, and, if necessary, the aforementioned matting agent, liquid medium, and other additives in water. The content of the polyurethane resin (A) is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, and even more preferably 20 to 40% by mass, based on the mass of the solid content of the coating material. The content of the quaternary ammonium salt-containing silane compound (B) is preferably 0.5 to 20% by mass, more preferably 0.5 to 15% by mass, and even more preferably 1 to 10% by mass, based on the mass of the solid content of the coating material. The content of the crosslinking agent is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1 to 20% by mass, based on the mass of the solid content of the coating material.

When producing an aqueous dispersion of polyurethane resin (A) and a coating material in a single process, first, as described above in the "Method for Producing an Aqueous Dispersion of Polyurethane Resin (A)" section, a urethane prepolymer having an NCO group, which is the precursor of polyurethane resin (A), is produced. Then, an amine compound containing a compound (f) having an amino group and an alkoxysilyl group is subjected to a chain extension reaction with the precursor of polyurethane resin (A) (urethane prepolymer having an NCO group) to obtain polyurethane resin (A) having silanol groups. Next, a silane compound (B) having a quaternary ammonium salt structure and a silanol group is added to the aqueous dispersion of polyurethane resin (A), and a crosslinking agent is added to the aqueous dispersion of polyurethane resin (A), thereby producing a coating material.

In one embodiment, it is also preferable to add a quaternary ammonium salt-containing silane compound (B) to an aqueous dispersion of polyurethane resin (A) and chemically bond the polyurethane resin (A) and silane compound (B) through a condensation reaction via the silanol groups they possess. Specifically, the quaternary ammonium salt-containing silane compound (B) is added to an aqueous dispersion of polyurethane resin (A), and hydrolysis and dehydration condensation reactions are carried out at 50 to 70°C within a pH range of 7 to 11 for approximately 0.5 to 2 hours.

<Examples of paint use>
The material of the object to which the paint of the present embodiment is applied is not particularly limited, and examples thereof include plastic, concrete, metal, paper, and fabrics such as woven and nonwoven fabrics. Of these, plastic is preferred.

Examples of plastic objects to which paint can be applied include olefin resins (polyethylene, polypropylene, etc.), ethylene propylene diene resins, styrene-acrylonitrile resins, polysulfone resins, polyphenylene ether resins, acrylic resins, silicone resins, fluorine-containing resins, polyester resins, polyamide resins, polyimide resins, polystyrene resins, polyurethane resins, polycarbonate resins, norbornene resins, cellulose resins, polyvinyl alcohol resins, polyvinyl formal resins, polyvinyl butyral resins, polyvinyl pyrrolidone resins, polyvinyl acetate resins, polyvinyl acetal resins, polyvinyl chloride, engineering plastics, biodegradable plastics, olefin thermoplastic elastomers (TPO), styrene thermoplastic elastomers (TPS), and polyester thermoplastic elastomers (TPEE). Plastic objects may be plastic molded products shaped to fit various product shapes, or plastic films or sheets.

A coating film can be formed by applying a coating material to the above-mentioned plastics so that the film thickness after drying is, for example, 5 to 25 μm, followed by heat treatment at 100 to 120°C for 20 minutes or at 150 to 180°C for 5 to 10 minutes. For example, when manufacturing vehicle interior materials (instrument panels, door trim, console boxes, etc.), a two-component water-based urethane resin or the like is applied to a TPO substrate sheet, and then the coating material of one embodiment of the present invention is applied on top of that by spray coating or gravure coating to form a coating film, followed by vacuum molding.

It is also useful for methods such as directly applying the paint of this embodiment to a plastic molded product, or for molding methods in which the paint of this embodiment is sprayed onto a mold and then polypropylene, urethane resin, or the like is placed into the mold. When applying the paint of this embodiment to a plastic molded product with poor adhesion, it is preferable to first treat the surface of the plastic molded product with a primer.

As described above in detail, the paint and the method for producing the paint according to one embodiment of the present invention can have the following configurations.
[1] A water dispersion of a polyurethane resin and an antibacterial agent are contained,
The polyurethane resin includes a polyurethane resin (A) having a silanol group,
The antibacterial agent comprises a silane compound (B) having a quaternary ammonium salt structure and a silanol group.
[2] The coating material according to the above [1], wherein the silane compound (B) is contained in the polyurethane resin (A) in a chemically unbonded state.
[3] The coating material according to the above [1], wherein the silane compound (B) is contained in the polyurethane resin (A) in a state of being chemically bonded to the polyurethane resin (A) as a condensation reaction product of a silanol group of the silane compound (B) and a silanol group of the polyurethane resin (A).
[4] The polyurethane resin (A) is a reaction product of a urethane prepolymer having an isocyanate group and an amine compound,
The urethane-based prepolymer is a reaction product of reaction components including: a compound (a) having an anionic hydrophilic group other than a hydroxyl group and an active hydrogen-containing group other than the anionic hydrophilic group; at least one compound (b) selected from the group consisting of polyols and polyamines; and a polyisocyanate (e);
The coating material according to any one of the above [1] to [3], wherein the amine compound includes a compound (f) having an amino group and an alkoxysilyl group.
[5] The coating material according to the above [4], wherein the urethane-based prepolymer is a reaction product of the compound (a), a polycarbonate polyol (b1), a chain extender (c), a polysiloxane (d) having an active hydrogen-containing group, and the polyisocyanate (e).
[6] The coating material according to [4] or [5] above, wherein the compound (f) is at least one selected from the group consisting of N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane.
[7] The coating material according to any one of the above [1] to [6], further comprising a crosslinking agent, wherein the crosslinking agent comprises at least one selected from the group consisting of an isocyanate-based crosslinking agent, a carbodiimide-based crosslinking agent, an oxazoline-based crosslinking agent, an epoxy-based crosslinking agent, and a metal complex-based crosslinking agent.
[8] The paint according to any one of the above [1] to [7], further comprising at least one matting agent selected from the group consisting of polyurethane gel particles and silica particles.
[9] A method for producing the coating material according to any one of [1] to [8] above,
a method for producing a coating material, the method comprising: subjecting a precursor of the polyurethane resin (A) to a chain extension reaction with an amine compound including a compound (f) having an amino group and an alkoxysilyl group to obtain the polyurethane resin (A) having a silanol group; and adding the silane compound (B) to an aqueous dispersion of the polyurethane resin (A).
[10] A method for producing the coating material according to the above [9], comprising adding the silane compound (B) to an aqueous dispersion of the polyurethane resin (A) to chemically bond the polyurethane resin (A) and the silane compound (B) to a condensation reaction via the silanol groups they possess.

The following describes in detail a paint according to one embodiment of the present invention based on examples, but the present invention is not limited to the following examples. In the following text, "parts" refers to parts by mass, and "%" refers to % by mass.

<Production of aqueous dispersion of polyurethane resin>
(Manufacturing example 1: PUD-1)
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen inlet tube, and a manhole was purged with nitrogen gas, and then 10.0 parts of dimethylolpropionic acid as the compound (a), 100.0 parts of polycarbonate diol (polyhexamethylene carbonate diol; number average molecular weight 2,000; trade name "Placcel CD220", manufactured by Daicel Corporation) as the compound (b), 2.0 parts of 1,3-butanediol as the chain extender (c), 10.0 parts of an alcohol-modified polysiloxane (number average molecular weight 1,900) represented by the following formula (15-1) as the polysiloxane (d), and 120.0 parts of acetone were added and dissolved uniformly.
Subsequently, 51.0 parts of hexamethylene diisocyanate (HDI) was added as polyisocyanate (e) (an amount such that the equivalent ratio (NCO/OH) of the NCO groups of polyisocyanate (e) to the total hydroxyl groups of (a) to (d) above was 2.0), and the reaction was carried out at 80°C until the NCO groups became 100% relative to the active hydrogen groups, thereby obtaining a urethane-based prepolymer having NCO groups.
Thereafter, the mixture was cooled to 50°C, and 440.0 parts of ion-exchanged water and 7.5 parts of triethylamine as a neutralizing agent (an amount equivalent to the anionic hydrophilic group (-COOH)) were added to uniformly emulsify the system. Next, 15.2 parts of ethylenediamine as an amine compound (an amount equivalent to the actually measured NCO %) was added to carry out a chain extension reaction of the urethane-based prepolymer having NCO groups. Finally, the acetone in the system was vacuum degassed and recovered.
In this way, an aqueous dispersion PUD-1 of polyurethane resin having a non-volatile content (solid content) concentration of 30% was obtained.

(Manufacturing example 2: PUD-2)
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen inlet tube, and a manhole was purged with nitrogen gas, and then 10.0 parts of dimethylolpropionic acid as the compound (a), 100.0 parts of polyhexamethylene carbonate diol (number average molecular weight 2,000; trade name "Placcel CD220", manufactured by Daicel Corporation) as the compound (b), 2.0 parts of 1,3-butanediol as the chain extender (c), 10.0 parts of an alcohol-modified polysiloxane (number average molecular weight 1,900) represented by the above formula (15-1) as the polysiloxane (d), and 120.0 parts of acetone were added and dissolved uniformly.
Subsequently, 51.0 parts of hexamethylene diisocyanate (HDI) was added as polyisocyanate (e) (an amount such that the equivalent ratio (NCO/OH) of the NCO groups of polyisocyanate (e) to the total hydroxyl groups of (a) to (d) above was 2.0), and the reaction was carried out at 80°C until the NCO groups became 100% relative to the active hydrogen groups, thereby obtaining a urethane-based prepolymer having NCO groups.
Thereafter, the mixture was cooled to 50°C, and 450.0 parts of ion-exchanged water and 7.5 parts of triethylamine as a neutralizing agent (an amount equivalent to the anionic hydrophilic group (-COOH)) were added to uniformly emulsify the system. Next, 13.7 parts of ethylenediamine as an amine compound (an amount equivalent to 90% of the measured NCO%) and 5.6 parts of N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane as compound (f) (an amount equivalent to 10% of the measured NCO%) were added to carry out a chain extension reaction. Finally, the acetone in the system was vacuum degassed and recovered.
In this way, an aqueous dispersion PUD-2 of polyurethane resin (A) having a nonvolatile content (solid content) concentration of 30% was obtained.

(Manufacturing example 3: PUD-3)
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen inlet tube, and a manhole was purged with nitrogen gas, and then 10.0 parts of dimethylolpropionic acid as the compound (a), 100.0 parts of polyhexamethylene carbonate diol (number average molecular weight 2,000; trade name "Placcel CD220", manufactured by Daicel Corporation) as the compound (b), 2.0 parts of 1,3-butanediol as the chain extender (c), 10.0 parts of an alcohol-modified polysiloxane (number average molecular weight 1,900) represented by the above formula (15-1) as the polysiloxane (d), and 120.0 parts of acetone were added and dissolved uniformly.
Subsequently, 51.0 parts of hexamethylene diisocyanate (HDI) was added as polyisocyanate (e) (an amount such that the equivalent ratio (NCO/OH) of the NCO groups of polyisocyanate (e) to the total hydroxyl groups of (a) to (d) above was 2.0), and the reaction was carried out at 80°C until the NCO groups became 100% relative to the active hydrogen groups, thereby obtaining a urethane-based prepolymer having NCO groups.
The mixture was then cooled to 50°C, and 480.0 parts of ion-exchanged water and 7.5 parts of triethylamine as a neutralizing agent (an amount equivalent to the anionic hydrophilic group (-COOH)) were added to uniformly emulsify the system. Next, 13.7 parts of ethylenediamine (an amount equivalent to 90% of the measured NCO%) as an amine compound and 5.6 parts of N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane (an amount equivalent to 10% of the measured NCO%) as compound (f) were added, and a chain extension reaction was carried out. Thereafter, a predetermined amount (5% of the solid content) of a quaternary ammonium salt-containing silane compound (B1) (trade name "X-12-1139", manufactured by Shin-Etsu Chemical Co., Ltd.) was added as antibacterial agent 1, and hydrolysis and dehydration condensation reactions were carried out under conditions of pH 7 to 11, 60°C, and 1 hour. Finally, the acetone in the system was vacuum degassed and recovered.
In this manner, an aqueous dispersion PUD-3 of polyurethane resin (A) having a nonvolatile content (solid content) of 30% was obtained, which contained polyurethane resin (A) and quaternary ammonium salt-containing silane compound (B1) in a chemically bonded state.

Table 1 shows an overview of the production conditions for the polyurethane resin aqueous dispersions PUD1 to PUD3 in Production Examples 1 to 3.

<Paint manufacturing>
(Examples 1 to 6, Comparative Examples 1 to 3)
The components (unit: parts) shown in the upper row of Table 2 (Table 2-1 and Table 2-2) were mixed to prepare matte paints for each Example and Comparative Example. The amounts of Antibacterial Agents 1 to 4 shown in Table 2 represent the amounts converted into active ingredients (solid content). The Antibacterial Agents 1 to 4, Matting Agents 1 and 2, and Crosslinking Agents shown in Table 2 are as follows:

Antibacterial agent 1: quaternary ammonium salt-containing silane compound (B1) (product name "X-12-1139", manufactured by Shin-Etsu Chemical Co., Ltd.; liquid with an active ingredient (a silane compound having two dimethyloctadecylammonium chloride structures) concentration of 30%)
Antibacterial agent 2: quaternary ammonium salt-containing silane compound (B2) (trade name "Nikkanon RB-40", manufactured by Nicca Chemical Co., Ltd.; liquid with an active ingredient (trimethoxysilane compound with a quaternary ammonium salt added) concentration of 40%)
Antibacterial agent 3: quaternary ammonium salt-containing silane compound (B3) (trade name "Sanitized T99-19", manufactured by SANITIZED AG; liquid with an active ingredient (tetradecyl [3-(trimethoxysilyl) propyl] dimethyl ammonium chloride) concentration of 40%)
Antibacterial agent 4: silver-based inorganic antibacterial agent (product name "Million Guard PG711", manufactured by Koa Glass Co., Ltd.; powder containing an active ingredient (silver-containing phosphate glass powder) concentration of 97% or more)
Matting agent 1: Polyurethane gel particles (product name "Art Pearl C-800 Transparent", manufactured by Negami Chemical Industrial Co., Ltd.; white powder with a volume average particle size of 6 μm and a Tg of -13°C)
Matting agent 2: silica particles (product name "ACEMATT TS-100", manufactured by EVONIK; dry silica with a volume average particle size of 9.5 μm)
Crosslinking agent: Carbodiimide-based crosslinking agent (trade name "Carbodilite V-04", manufactured by Nisshinbo Chemical Inc.; aqueous liquid with a 40% concentration of active ingredient (non-volatile content: aqueous crosslinking agent obtained by adding hydrophilic segments to polycarbodiimide resin))

<Paint evaluation>
[Paint suitability]
The coating materials produced in each of the Examples and Comparative Examples were evaluated for dispersibility, sedimentation, storage stability, and coatability as described below.

(dispersibility)
The paint was visually observed immediately after preparation, and the dispersibility (degree of aggregation) of the polyurethane resin and the matting agent was evaluated according to the following evaluation criteria.
A: No problem, dispersed almost uniformly.
B: A small amount of coarse grains is observed.
C: Coarse particles are observed.

(sedimentation)
Six hours after preparation, the paint was visually observed, and the settling of the polyurethane resin and matting agent was evaluated according to the following evaluation criteria.
A: No problem, almost no sediment was observed.
B: A small amount of sediment is observed.
C: Sediment is observed.

(Storage stability)
The prepared coating material was allowed to stand at room temperature (23°C) for 3 months, and then visually observed, and the degree of aggregation and sedimentation of the polyurethane resin and matting agent was evaluated according to the following evaluation criteria.
A: No precipitate is formed, or the precipitate can be easily broken down into smaller pieces.
B: A portion of the product solidified at the bottom and was difficult to redisperse.
C: The entire precipitate solidifies and does not redisperse.

(Applicability)
The prepared paint was applied to a hiding power measurement paper (trade name "LENETA N2C-2", manufactured by Leneta Company, Inc.) using a bar coater, and the hiding power was evaluated according to the following evaluation criteria.
A: It was applied without any problems.
B: Slight surface irregularities are observed.
C: Surface irregularities are observed.

<Preparation and evaluation of coating film>
The paints produced in each Example and Comparative Example were applied to the substrate sheets used in the evaluations described below using a bar coater, dried at 100°C for 2 minutes, and then aged at 50°C for 24 hours to form coating films with a thickness of approximately 9 μm. The coating films were subjected to the tests and evaluations described below. The results of each evaluation are shown in the lower part of Table 2.

[Antibacterial]
Using test pieces (coated test pieces) in which a coating film was provided on a PET film (trade name "Lumirror S10", manufactured by Toray Industries, Inc.) as a base sheet, antibacterial tests were conducted on the coating film of the test pieces in accordance with the provisions of JIS Z2801:2010 (ISO 22196:2007). Specifically, the tests were conducted according to the following procedure.
(1) 0.4 mL of bacterial suspension was dropped onto the coating side of a 5 cm square test piece, and the piece was covered with a 4 cm square film. The same procedure was also carried out on a blank test piece (uncoated test piece) consisting of only the substrate (PET film) without a coating film. Escherichia coli and Staphylococcus aureus were used as the bacterial suspension.
(2) The test specimens were incubated at a temperature of 35±1°C and a relative humidity of 90% or more for 24 hours.
(3) After leaving the test piece to stand, the test bacteria on the test piece were washed out and collected, and the number of live bacteria per 1 ^cm2 was measured.
(4) The antibacterial activity value R was calculated using the following formula: The larger the antibacterial activity value R, the higher the antibacterial property.
R = _Ut - _At
Ut : average logarithm of the number of viable bacteria per 1 ^cm2 of the blank test piece after 24 hours. _At : average logarithm of the number of viable bacteria per 1 ^cm2 of the test piece (coated test piece) after 24 hours.

[Matte finish]
For the coating films provided on the substrate sheets shown below, gloss values (60° incident light/60° reflected light) were measured using a direct reading haze computer HGM-2DP (manufactured by Suga Test Instruments Co., Ltd.).
- TPO (olefin-based thermoplastic elastomer)
・Black PVC (black polyvinyl chloride)
・Light-colored PVC (light-colored polyvinyl chloride)
・PU synthetic leather (polyurethane synthetic leather)

[Wear resistance]
The coating film provided on the above-mentioned "PU synthetic leather" substrate sheet was subjected to abrasion using a Gakushin-type abrasion tester under the conditions of No. 6 canvas and a load of 1 kg, and the number of abrasions until the appearance changed was measured by visually observing the coating surface every 100 abrasions. Two measurements were taken for each test piece, and the average value was calculated.

[Bending resistance]
Test pieces each having a coating film formed on the above-mentioned "black PVC" substrate sheet were subjected to a cold bending resistance test under the following conditions, and the state of the coating film surface was evaluated by visual observation.
・Device: Dematcha bending tester with low-temperature chamber (manufactured by Yasuda Seiki Seisakusho Co., Ltd.)
・Test piece size: 150 mm x 50 mm
Evaluation range: 100mm x 50mm
Test conditions: -10°C / 72-108% bending / 30,000 times Evaluation criteria:
○: No cracks.
×: Cracks occurred.

[Light resistance]
For each coating film provided on the above-mentioned "TPO,""PVCblack," and "PU synthetic leather" substrate sheets, a xenon lamp light resistance tester was used to check for changes in appearance of the coating film, and the light resistance of the coating film was evaluated according to the following evaluation criteria. When the substrate sheet was TPO or PU synthetic leather, the exposure dose was 300 Mj, and when the substrate sheet was PVC black, the exposure dose was 200 Mj.
○: No change.
×: Whitened.

[Stain resistance]
On the coating film provided on the above-mentioned "light-colored PVC" substrate sheet, 1 g of coffee liquid (a solution prepared by dissolving 1 g of instant coffee powder (trade name "Nescafe", manufactured by Nestle Japan Ltd.) in 100 mL of water) or 1 g of mustard (trade name "French's mustard", manufactured by HEINZ GmbH) was dropped, and after 24 hours, the coating film was wiped off with ion-exchanged water, and the change in appearance of the coating film was observed to evaluate the stain resistance of the coating film according to the following evaluation criteria.
○: No change.
×: Dirt.

The paints of Examples 1 to 6 were found to be capable of forming coating films with good antibacterial properties while exhibiting paint suitability comparable to that of the paint of Comparative Example 1 (a paint containing no antibacterial agent). On the other hand, the paint of Comparative Example 2 (a paint containing a silver-based inorganic antibacterial agent) had antibacterial properties, but exhibited poor dispersibility and sedimentation properties.

Furthermore, the paint of Comparative Example 3 did not exhibit antibacterial properties. This is believed to be because the polyurethane resin in PUD-1 used in the paint of Comparative Example 3 does not contain silanol groups. That is, in the paint of Comparative Example 3, a condensation reaction between the polyurethane resin and the antibacterial agent (quaternary ammonium salt-containing silane compound (B1)) did not occur, either in the paint or during coating film formation, and the antibacterial agent was not immobilized in the polyurethane resin. In contrast, the polyurethane resin (A) in PUD-2 used in the paints of Examples 1 to 5 contains silanol groups, and therefore a condensation reaction between the polyurethane resin (A) and the antibacterial agent (quaternary ammonium salt-containing silane compounds (B1), (B2), and (B3)) occurred during coating film formation. This immobilized the antibacterial agent in the polyurethane resin (A), resulting in the formation of a coating film with good antibacterial properties. Furthermore, the paint of Example 6 contains the polyurethane resin (A) and antibacterial agent (quaternary ammonium salt-containing silane compound (B1)) in PUD-3 in a chemically bonded state as condensation products of the silanol groups they each possess, which is thought to be why a coating film with good antibacterial properties was formed.

A specified adhesion test (test under conditions of 120°C/10 kg/1 minute lamination) was conducted on test pieces in which a coating film was applied to "TPO" as a base sheet. The results showed that the paints of Examples 1, 2, and 6, which used antibacterial agent 1 (quaternary ammonium salt-containing silane compound (B1)), were capable of forming coating films with good adhesion comparable to that of Comparative Example 1, which did not contain an antibacterial agent.

In addition, a prescribed heat resistance test (test at 120°C/400 hours) was conducted on test pieces in which a coating film was applied to a "light-colored PVC" substrate sheet. The results showed that the paints of Examples 1 to 3 and 6, which used antibacterial agent 1 (quaternary ammonium salt-containing silane compound (B1)), were capable of forming coating films with good heat resistance comparable to that of Comparative Example 1, which did not contain an antibacterial agent.

Furthermore, a prescribed vacuum formability test (test under conditions of a surface temperature of 160 to 170°C) was conducted on test pieces in which a coating film was provided on "TPO" as a base sheet. As a result, it was found that the coating film of Example 4, which used antibacterial agent 2 (quaternary ammonium salt-containing silane compound (B2)), and the coating film of Example 5, which used antibacterial agent 3 (quaternary ammonium salt-containing silane compound (B3)), exhibited superior formability compared to the coating film of Comparative Example 1, which did not contain an antibacterial agent.

Claims (10)

Contains an aqueous dispersion of polyurethane resin and an antibacterial agent,
The polyurethane resin includes a polyurethane resin (A) having a silanol group,
The antibacterial agent includes a silane compound (B) having a quaternary ammonium salt structure and a silanol group,
The polyurethane resin (A) is a reaction product of a urethane prepolymer having an isocyanate group and an amine compound,
The urethane-based prepolymer is a reaction product of reaction components including a compound (a) having an anionic hydrophilic group other than a hydroxyl group and an active hydrogen-containing group other than the anionic hydrophilic group, a polycarbonate polyol (b1), and a polyisocyanate (e),
The amine compound contains both a compound (f) having an amino group and an alkoxysilyl group, and ethylenediamine . The paint according to claim 1, wherein the silane compound (B) is contained in the polyurethane resin (A) in a chemically unbonded state. The paint according to claim 1, wherein the silane compound (B) is contained in a state chemically bonded to the polyurethane resin (A) as a condensation reaction product of a silanol group contained in the silane compound (B) and a silanol group contained in the polyurethane resin (A). The coating material according to any one of claims 1 to 3, wherein the silane compound (B) has a siloxane bond (-Si-O-Si-) containing a silicon atom in the silanol group in one molecule, and the number of the quaternary ammonium salt structures in one molecule of the silane compound (B) is two. The coating material according to any one of claims 1 to 4, wherein the urethane- based prepolymer is a reaction product of the compound (a), the polycarbonate polyol ( b1), a chain extender (c), a polysiloxane (d) having an active hydrogen-containing group, and the polyisocyanate (e). The paint according to any one of claims 1 to 5, wherein the compound (f) comprises at least one selected from the group consisting of N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane , 3-aminopropyltrimethoxysilane, and 3- aminopropyltriethoxysilane. Further containing a crosslinking agent,
The coating material according to any one of claims 1 to 6, wherein the crosslinking agent comprises at least one selected from the group consisting of an isocyanate-based crosslinking agent, a carbodiimide-based crosslinking agent, an oxazoline-based crosslinking agent, an epoxy-based crosslinking agent, and a metal complex-based crosslinking agent. The paint according to any one of claims 1 to 7, further comprising at least one matting agent selected from the group consisting of polyurethane gel particles and silica particles. A method for producing the paint according to any one of claims 1 to 8,
a urethane-based prepolymer having an isocyanate group, which is a precursor of the polyurethane-based resin (A), undergoing a chain extension reaction with the compound (f) having an amino group and an alkoxysilyl group, and the amine compound containing both ethylenediamine , to obtain the polyurethane-based resin (A) having a silanol group; and adding the silane compound (B) to an aqueous dispersion of the polyurethane-based resin (A). The method for producing a paint according to claim 9, further comprising adding the silane compound (B) to an aqueous dispersion of the polyurethane resin (A) to chemically bond the polyurethane resin (A) and the silane compound (B) through a condensation reaction at the silanol groups they possess.