Powder coating composition, cured coating film, article, and method for manufacturing powder coating composition

Abstract

To provide a powder coating composition that can form a coating layer capable of exhibiting a desired function in sustained manner.SOLUTION: A powder coating composition according to one embodiment of the present invention comprises a thermosetting resin (A) and inorganic particles (B). The inorganic particles (B) comprise one or more metals or metal ions selected from silver, copper, cobalt, nickel and zinc and have a median diameter of 10 μm or more and 100 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to powder coating compositions, cured coating films, articles, and methods for producing powder coating compositions. [Background technology]

[0002] Conventionally, when coating a substrate with paint, attempts have been made to impart desired functions to the resulting coating film. For example, Patent Document 1 discloses a powder coating containing functional fine particles and resin particles. It is said that such a powder coating makes it possible to impart water repellency and antibacterial properties to the resulting coating film. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-12107 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, as a result of our investigation, we have found that there is still room for improvement in the functionality of the coating film disclosed in Patent Document 1. In other words, it has become clear that the coating described in Patent Document 1 has room for improvement in terms of the degree of functionality exhibited at the time of application, and that the desired functionality tends not to be maintained when this coating is used continuously.

[0005] In view of the above circumstances, the present invention aims to provide a powder coating composition, etc., that can provide a coating film that sustainably exhibits the desired function. [Means for solving the problem]

[0006] According to one aspect of the present invention, a powder coating composition is provided. This powder coating composition comprises a thermosetting resin (A) and inorganic particles (B). The inorganic particles (B) contain one or more metals or metal ions selected from the group consisting of silver, copper, cobalt, nickel, and zinc, and are particles with a median diameter of 10 μm or more and 100 μm or less.

[0007] According to the above embodiment, a powder coating composition or the like is provided that can provide a coating film in which the desired function is continuously exhibited. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below. The various features shown in the embodiments below can be combined with each other. Unless otherwise specified, "~" in this specification represents the following from the above.

[0009] <Powder coating composition> The powder coating composition of this embodiment is as follows. A powder coating composition, It contains a thermosetting resin (A) and inorganic particles (B), The inorganic particles (B) are a powder coating composition comprising one or more metals or metal ions selected from the group consisting of silver, copper, cobalt, nickel, and zinc, and having a median diameter of 10 μm or more and 100 μm or less. The following describes the components constituting the powder coating composition of this embodiment, the method for manufacturing the powder coating composition, and its uses.

[0010] [Thermosetting resin (A)] The powder coating composition of this embodiment contains a thermosetting resin (A). In this specification, "thermosetting resin (A)" refers to a compound having a functional group that can form chemical bonds upon heating, and encompasses all components that can contribute to the formation of a cured product. That is, even low-molecular-weight compounds (for example, those with a molecular weight of 1000 or less) are treated as part of the thermosetting resin (A) if they react with other compounds under heating conditions to form a cured product.

[0011] The thermosetting resin (A) contained in the powder coating composition of this embodiment may be appropriately selected from known materials. Examples of the components that may be contained in the thermosetting resin (A) include polyester resins, epoxy resins, silicone resins, silicone-modified resins, formaldehyde resins, phenol resins, melamine resins, urea resins, benzoguanamine resins, alkyd resins, diallyl phthalate resins, polyurethane resins, thermosetting polyimide resins, crosslinked acrylic resins (e.g., crosslinked polymethyl methacrylate resins), crosslinked polystyrene resins, and polyamic acid resins (resins that are imidized by heating to form a polyimide structure).

[0012] In the powder coating composition of this embodiment, when the total amount of the powder coating composition is 100 parts by mass, the content of the thermosetting resin (A) is preferably 5 parts by mass or more and 99.8 parts by mass or less, more preferably 8 parts by mass or more and 99.5 parts by mass or less, still more preferably 10 parts by mass or more and 99 parts by mass or less, particularly preferably 12 parts by mass or more and 98 parts by mass or less, and most preferably 15 parts by mass or more and 95 parts by mass or less. By setting the content within such a range, the curability and handleability of the powder coating composition are improved, and it becomes easier for the resulting cured coating film to exhibit desired functions.

[0013] In the powder coating composition of this embodiment, the thermosetting resin (A) contains, for example, a polyester resin. Note that for the polyester resin, a polyester resin having crosslinkability to other components is preferably applied. Here, the polyester resin is obtained, for example, by polycondensation of a polybasic acid (specifically, a dibasic acid, more specifically, a dicarboxylic acid) and a polyhydric alcohol (specifically, a diol). The polybasic acid as a raw material may be equivalent to the polybasic acid in the reaction system, such as an acid anhydride or an ester. Alternatively, the polyester resin typically contains a structural unit derived from a polybasic acid and a structural unit derived from a polyhydric alcohol.

[0014] Examples of polybasic acids used as raw materials for polyester resins include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,2-octadecanedicarboxylic acid, maleic acid, fumaric acid, cyclohexanedicarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, trimellitic acid, pyromellitic acid, trimesic acid, and the like.

[0015] As polybasic acids, polybasic acids containing an aromatic ring structure or an alicyclic ring structure are preferred because their rigid structures can enhance the durability (mechanical strength) of the coating film. In particular, polybasic acids containing an aromatic ring structure such as terephthalic acid and isophthalic acid are preferred in terms of the durability of the cured coating film, fluidity during baking, and ease of availability.

[0016] Examples of polyhydric alcohols used as raw materials for polyester resins include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, spiroglycol, 1,10-decanediol, 1,4-cyclohexanedimethanol, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and the like.

[0017] The polyhydric alcohol preferably contains a branched or cyclic hydrocarbon structure, more preferably a branched hydrocarbon structure. It is considered that this makes the polyester resin moderately rigid and further enhances the weather resistance and durability of the cured coating film compared to the case where it contains only a linear hydrocarbon structure.

[0018] From another perspective, the polyhydric alcohol preferably has 2 to 15 carbon atoms, more preferably 2 to 10, and even more preferably 4 to 8 carbon atoms. It is believed that having a carbon number within this range improves the fluidity of the polyester resin during the baking of the powder coating composition.

[0019] The weight-average molecular weight of the polyester resin is not particularly limited, but is, for example, 3,000 to 50,000, preferably 5,000 to 40,000. The degree of dispersion (weight-average molecular weight / number-average molecular weight) of the polyester resin is not particularly limited, but is, for example, 1 to 10, preferably 1.4 to 8. The weight-average molecular weight and dispersion can be measured as values ​​equivalent to standard polystyrene using gel permeation chromatography (GPC).

[0020] The properties of the polyester resin are not particularly limited. However, from the viewpoint of obtaining a stable coating film, it is preferable that it be solid at room temperature (25°C). Furthermore, the softening point of the polyester resin is preferably 80 to 150°C, and more preferably 100 to 130°C. By adjusting it within this range, the smoothness of the resulting cured coating film can be improved.

[0021] Furthermore, the thermosetting resin (A) may contain only one type of polyester resin, or it may contain two or more types of polyester resins.

[0022] When the powder coating composition of this embodiment contains a polyester resin, the amount of the polyester resin is not particularly limited, but is, for example, 10 to 90 parts by mass, preferably 15 to 80 parts by mass, and more preferably 20 to 75 parts by mass, when the total amount of the powder coating composition is 100 parts by mass.

[0023] The thermosetting resin (A) may also include a combination of a polyester resin having a carboxyl group and a β-hydroxyalkylamide compound, as described later. In this case, the polyester resin will have a carboxyl group at its terminal end, and its acid value is preferably 10 to 100 mgKOH / g, more preferably 10 to 60 mgKOH / g, and even more preferably 20 to 40 mgKOH / g. The acid value of the polyester resin can be measured according to the provisions of JIS K 0070.

[0024] Specific examples of polyester resins containing carboxyl groups include CRYLCOAT® 2661-3 (trade name, manufactured by Daicel Ornex Co., Ltd.); GV-235 (trade name, manufactured by Nippon Yupika Co., Ltd.); and Uralac® P6800 (trade name, manufactured by DSM Co., Ltd.).

[0025] The β-hydroxyalkylamide compound that can be combined with the polyester resin having a carboxyl group can be any compound that has a β-hydroxyalkylamide group in its molecule. A β-hydroxyalkylamide group is one in which a hydroxyl group is bonded to the carbon at the β position of an amide group. The β-hydroxyalkylamide compound can be crosslinked with the polyester resin having a carboxyl group due to its hydroxyl group. Therefore, it also functions as a curing agent for the polyester resin in powder coating compositions.

[0026] Furthermore, from the viewpoint of having good crosslinkability with polyester resins having carboxyl groups, the β-hydroxyalkylamide compound preferably contains two or more β-hydroxyalkylamide groups per molecule, more preferably two to six, and even more preferably four to six.

[0027] More specifically, the β-hydroxyalkylamide compound preferably contains two or more structures represented by the following general formula (F1) in one molecule, more preferably 2 to 6, and even more preferably 4 to 6.

[0028] [Chemical formula]

[0029] In general formula (F1), R 1 and R 2 each independently represent a hydrogen atom or a monovalent organic group. In general formula (F1), * represents a bond. However, at least one (both may be) of R 1 and R 2 is a monovalent organic group represented by the following general formula (F2).

[0030] [Chemical formula]

[0031] In general formula (b2), R 3 , R 4 , R 5 and R 6 each independently represent a hydrogen atom or a monovalent organic group. In general formula (F2), * represents a bond.

[0032] Examples of the monovalent organic groups in R 1 and R 2 in general formula (F1) include, for example, an alkyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aralkyl group, an alkylcarbonyl group, an alkoxycarbonyl group, an alkylcarbonyloxy group, and the like. The alkyl group may be either straight-chain or branched, and examples thereof include an alkyl group having 1 to 20 carbon atoms, preferably a straight-chain and branched alkyl group having 1 to 12 carbon atoms. Examples of the cycloalkyl group include a cycloalkyl group having 3 to 8 carbon atoms. The alkoxy group may be straight-chain, branched, or cyclic, and examples thereof include an alkoxy group having 1 to 10 carbon atoms, preferably a straight-chain and branched alkoxy group having 1 to 6 carbon atoms, and a cyclic alkoxy group having 3 to 8 carbon atoms. Examples of aralkyl groups include the benzyl group and the phenethyl group. Examples of alkylcarbonyl groups, alkoxycarbonyl groups, and alkylcarbonyloxy groups include groups that combine a carbonyl unit or a carbonyloxy unit with the alkyl or alkoxy group mentioned above.

[0033] R of the general formula (F2) 3 , R 4 , R 5 and R 6 In this, the monovalent organic group is R of general formula (F1). 1 and R 2 Examples similar to the monovalent organic group in [the given text] can be cited.

[0034] In general formula (F1), preferably, (i)R 1 and R 2 (ii)R 1 and R 2 Both are monovalent organic groups represented by general formula (F2). In general formula (F2), preferably, R 3 , R 4 , R 5 and R 6 All of them are hydrogen atoms.

[0035] The β-hydroxyalkylamide compound is preferably one represented by the following general formula (F3).

[0036] [ka]

[0037] In the general formula (F3), n is an integer of 2 or more (preferably 2 to 6, more preferably 4 to 6), and A is an n-valent organic group. 1 and R 2 The definition and specific examples are the same as those for the general formula (F1).

[0038] An example of an n-valent organic group A is a group obtained by removing n hydrogen atoms from any organic compound. For example, when n is 2, examples include linear alkylene groups such as -CH2- and -C2H4-, branched alkylene groups such as -CH2-C(CH3)2-CH2-, ether-containing groups such as -C2H4-O-C2H4-, cycloalkylene groups, groups obtained by removing two hydrogen atoms from alicyclic-containing groups, groups obtained by removing two hydrogen atoms from aromatic ring-containing groups such as phenylene groups and naphthylene groups, and groups obtained by removing two hydrogen atoms from groups containing heterocyclic structures. Among these, linear alkylene groups or branched alkylene groups are preferred from the viewpoint of the flexibility of the cured coating film, and linear alkylene groups are more preferred.

[0039] When n is 3 or greater, A can be a group obtained by removing 3 or more hydrogen atoms from a linear or branched alkane, a group obtained by removing 3 or more hydrogen atoms from a cycloalkane or alicyclic compound, a group obtained by removing 3 or more hydrogen atoms from an aromatic ring compound, a group obtained by removing 3 or more hydrogen atoms from a heterocyclic compound, and so on.

[0040] The number of carbon atoms in the n-valent organic group of A is not particularly limited, but is typically 1 to 30, preferably 2 to 25, and more preferably 3 to 20. Furthermore, the n-valent organic group of A may have any substituents.

[0041] β-hydroxyalkylamide compounds can be produced, for example, by reacting a carboxylic acid or its lower alkyl ester with a β-hydroxyalkylamine.

[0042] Examples of commercially available β-hydroxyalkylamide compounds include the Primid® series (manufactured by EMS-CHEMIE AG), particularly Primid® XL-552, Primid® QM-1260, and Primid® SF-4510.

[0043] The powder coating composition of this embodiment may contain only one β-hydroxyalkylamide compound, or it may contain two or more β-hydroxyalkylamide compounds.

[0044] Furthermore, if the powder coating composition contains a β-hydroxyalkylamide compound, its content is preferably 1 to 20 parts by mass, more preferably 3 to 20 parts by mass, and even more preferably 5 to 20 parts by mass, per 100 parts by mass of the carboxyl group-containing polyester resin. By setting the content of the β-hydroxyalkylamide compound within this range, it becomes easier to obtain a cured coating film with appropriate strength.

[0045] Furthermore, the thermosetting resin (A) may include a combination of a polyester resin having hydroxyl groups and an isocyanate compound, as described later. In this case, the polyester resin will have hydroxyl groups at its ends, and its hydroxyl value is preferably 10 to 150 mgKOH / g, more preferably 15 to 100 mgKOH / g, and even more preferably 20 to 80 mgKOH / g. The hydroxyl value of the polyester resin can be measured in accordance with the provisions of JIS K 0070.

[0046] Specific examples of polyester resins containing hydroxyl groups include CRYLCOAT® 2890-0 (product name, manufactured by Daicel Ornex Co., Ltd.); GV-110 and GV-500 (product names, manufactured by Nippon Yupika Co., Ltd.); Uralac® P1580 (product name, manufactured by DSM Corporation); and Finedic M-8020 and M-8100 (product names, manufactured by DIC Corporation).

[0047] The isocyanate compounds that can be combined with polyester resins having hydroxyl groups include not only compounds having isocyanate groups in their molecules, but also compounds in which the isocyanate groups are blocked (so-called "blocked isocyanate compounds"). In this specification, such blocked compounds will also be referred to as isocyanate compounds. Furthermore, the isocyanate compounds used in such curing systems may be one type or two or more types.

[0048] Furthermore, it is preferable that the isocyanate compound is polyfunctional, that is, a compound having two or more isocyanate groups (including blocked isocyanate groups) in one molecule. Specific examples of isocyanate compounds include the following:

[0049] Aliphatic diisocyanate compounds: hexamethylene diisocyanate, trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, pentamethylene diisocyanate, lysine diisocyanate, 1,3-butylene diisocyanate, etc.

[0050] Alicyclic diisocyanate compounds: isophorone diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methylcyclohexane-2,4-(or-2,6-)diisocyanate, 1,3-(or 1,4-)di(isocyanatomethyl)cyclohexane, 1,4-cyclohexanediisocyanate, 1,3-cyclopentanediisocyanate, 1,2-cyclohexanediisocyanate, etc.

[0051] Aromatic diisocyanate compounds: xylylene diisocyanate, metaxylylene diisocyanate, tetramethylxylylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, (m- or p-)phenylene diisocyanate, etc.

[0052] Other polyisocyanates: Polyisocyanate compounds having three or more isocyanate groups, such as triphenylmethane-4,4',4''-triisocyanate; adducts obtained by reacting polyols such as ethylene glycol, propylene glycol, 1,4-butylene glycol, polyalkylene glycol, trimethylolpropane, and hexanetriol with an excess amount of polyisocyanate compounds relative to the hydroxyl groups; biuret-type adducts such as hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and 4,4'-methylenebis(cyclohexyl isocyanate); isocyanuric ring-type adducts, etc.

[0053] Furthermore, blocked isocyanate compounds are obtained by blocking some or all of the isocyanate groups of the above-mentioned isocyanate compounds with a blocking agent. More specifically, blocked isocyanate compounds in which the isocyanate groups are blocked by blocking agents such as alcohols, phenols, lactams, and oximes can also be used as curing agents in thermosetting resins (A).

[0054] Furthermore, phenol-based or lactam-based blocking agents are preferred as the blocking agent. Examples of phenolic blocking agents include phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, hydroxydiphenyl, t-butylphenol, and methyl hydroxybenzoate. Examples of lactam-based blocking agents include ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; examples of oxime-based blocking agents include acetaldehyde, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime.

[0055] In one embodiment, the isocyanate compound contains an alicyclic structure. It is believed that the inclusion of an alicyclic structure in the isocyanate compound can make the cured coating film more rigid. Specific examples of isocyanate compounds containing an alicyclic structure include those mentioned above as alicyclic diisocyanate compounds, as well as those described below.

[0056] As an isocyanate compound containing an alicyclic structure, for example, from the viewpoint of availability, compounds having a trimer structure of isophorone diisocyanate can be preferred (the isocyanate group in this compound may or may not be blocked, but is preferably blocked). According to publicly available information, the trimer of isophorone diisocyanate can be represented by the following general formula (F4). In general formula (F4), the three Rs are each independently an isocyanate group (-NCO) or an isocyanate group blocked by a blocking agent.

[0057] [ka]

[0058] Commercially available isocyanate compounds may be used as the isocyanate compound. An example of this is the VESTAGON® series from Evonik. The compounds in this series are isocyanate compounds (including blocked isocyanate compounds).

[0059] When the powder coating composition of this embodiment contains an isocyanate compound, its content is preferably 3 to 45 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 10 to 35 parts by mass, per 100 parts by mass of the hydroxyl group-containing polyester resin. By setting the isocyanate compound content within this range, it becomes easier to obtain a cured coating film with appropriate strength.

[0060] Furthermore, when the thermosetting resin (A) includes a combination of a polyester resin having hydroxyl groups and an isocyanate compound, a curing aid such as a tin catalyst like dibutyltin laurate can be added to improve curability. The amount of this additive can be set as appropriate.

[0061] Furthermore, it is preferable that the thermosetting resin (A) also contains an epoxy resin. The powder coating composition of this embodiment may contain only such an epoxy resin as the thermosetting resin (A), or it may be composed of the thermosetting resin (A) together with other resins (such as polyester resin).

[0062] Examples of epoxy resins include bisphenol-type epoxy resins such as bisphenol A-type epoxy resin and bisphenol F-type epoxy resin, naphthalene-type epoxy resin, biphenyl-type epoxy resin, novolac-type epoxy resin, cyclic aliphatic epoxy resin, glycidylamine-type resin, heterocyclic epoxy resin, and polyfunctional epoxy resin. These can be used individually or in combination.

[0063] Such epoxy resins available include jER(registered trademark) 1002, jER(registered trademark) 1004, jER(registered trademark) 1004F and jER(registered trademark) 1007 (product names, manufactured by Mitsubishi Chemical Corporation), EPICLON 3050 and EPICLON 4050 (product names, manufactured by DIC Corporation).

[0064] The softening point of the epoxy resin is not particularly limited, but is preferably 60 to 150°C, and the epoxy equivalent is also not particularly limited, but is preferably 400 to 3000.

[0065] Furthermore, when the powder coating composition of this embodiment contains epoxy resin, a polyester resin containing carboxyl groups or a polyester resin containing hydroxyl groups may be used in combination with the epoxy resin. By using multiple types of resins in this way, the curability of the epoxy resin can be improved.

[0066] Furthermore, when the powder coating composition of this embodiment contains epoxy resin, a curing aid can also be included along with the epoxy resin. Examples of curing aids for epoxy resin include nitrogen-containing aromatic ring compounds such as imidazole compounds and pyridine compounds, and amine compounds. The amount of these compounds can be set as appropriate.

[0067] When the powder coating composition of this embodiment contains epoxy resin, the amount of epoxy resin is not particularly limited, but is, for example, 10 to 90 parts by mass, preferably 15 to 80 parts by mass, and more preferably 20 to 75 parts by mass, when the total amount of the powder coating composition is 100 parts by mass.

[0068] [Inorganic particles (B)] The powder coating composition of this embodiment contains inorganic particles (B). Here, the inorganic particles (B) contain one or more metals or metal ions selected from the group consisting of silver, copper, cobalt, nickel, and zinc, and the particles have a median diameter of 10 μm or more and 100 μm or less.

[0069] The metals or metal ions mentioned above typically possess antiviral or antibacterial activity. Therefore, as described in Patent Document 1 above, inorganic particles have conventionally been included in powder coating compositions to impart functionality to coating films. However, our research has shown that it is desirable to appropriately control the median diameter of the inorganic particles included. In other words, when inorganic particles containing metals, etc., are small in size, it can be difficult to achieve the desired functionality even after forming a coating film, or it may be difficult to achieve long-term functional expression. In contrast, it has been found that increasing the particle size of the inorganic particles included in the powder coating composition makes it easier to obtain a coating film that sustainably exhibits the desired functionality. Although the reason for this is not entirely clear, it is thought that when large-particle inorganic particles are used, the inorganic particles tend to be present near the surface of the formed cured coating film, and due to their size, they tend not to be easily removed from the coating film.

[0070] Here, the inorganic particles (B) may be particles composed substantially only of metal (so-called zero-valent metals), such as silver powder or copper powder, or they may be inorganic salts composed of ions of the above-mentioned metal, or particles composed of oxides of the above-mentioned metal. Furthermore, the inorganic particles (B) may be particles on which metal or metal ions are supported. The support for supporting such metal or metal ions can be set as appropriate, but for example, it is one selected from the group consisting of zeolite, silica gel, glass, alumina, activated carbon, and titania. Furthermore, the metal or metal ion contained in the inorganic particles (B) is preferably silver, copper, or zinc, more preferably silver or copper, and even more preferably silver. The inorganic particles (B) may also contain metals or metal ions other than silver, copper, cobalt, nickel, and zinc.

[0071] Furthermore, the median diameter of the inorganic particles (B) is 10 μm or more and 100 μm or less, exemplified by 15 μm to 95 μm or less, and may also be 20 μm or more and 90 μm or less, preferably 25 μm or more and 85 μm or less, more preferably 30 μm or more and 80 μm or less, and even more preferably 35 μm or more and 70 μm or less. By adjusting the median diameter within this range, the above-mentioned effects are more easily achieved, and the handling properties of the powder coating composition are improved. The median diameter of the inorganic particles (B) can also be estimated from the raw materials used when formulating the powder coating composition. Alternatively, the median diameter can be estimated from the remaining inorganic particles (B) after removing components other than the inorganic particles (B) from the prepared powder coating composition. An example of a measuring device that can be used to measure the median diameter is the particle distribution analyzer MT3000II (manufactured by Microtrac-Bell Co., Ltd.).

[0072] Furthermore, the median diameter of the inorganic particles (B) contained in the powder coating composition of this embodiment can also be estimated by analyzing the cured coating film obtained by curing the powder coating composition. Specifically, by preparing a cured coating film of a certain thickness from the powder coating composition of this embodiment and polishing this cured coating film, the median diameter of the inorganic particles (B) can be estimated by observing the inorganic particles (B) present in the cured coating film. Typically, a cured coating film with a thickness of about 60 μm is prepared from the powder coating composition of this embodiment, and the surface of the cured coating film is polished to a depth of about 30 μm using a polishing device. The exposed surface is then observed using a microscope, and the average major axis of the component corresponding to inorganic particles (B) can be determined. For polishing equipment, for example, a PlanarMet 300 (manufactured by Buehler) can be used, and for microscopes, for example, a digital microscope VHX-7000 (manufactured by Keyence Corporation) can be used. Furthermore, the average major axis can be calculated by measuring the major axis of 100 inorganic particles (B) present on the exposed surface and taking the average value. Furthermore, while the cured coating thickness does not necessarily have to be set to 60 μm, it is desirable to analyze the surface of the region close to the center of the cured coating when determining the median diameter. Therefore, when the thickness of the cured coating to be analyzed is X [μm], it is preferable to set the thickness to be polished in the range of 0.3X [μm] to 0.7X [μm].

[0073] The powder coating composition of this embodiment may contain only one type of inorganic particle (B), or it may contain two or more types of inorganic particles (B). However, the median diameter mentioned above refers to the diameter of the entire component corresponding to the inorganic particles (B) that contain one or more metals or metal ions selected from the group consisting of silver, copper, cobalt, nickel, and zinc. In other words, even if a raw material containing small particles such as silver is used in part, as long as the inorganic particles (B) as a whole satisfy the median diameter mentioned above, it may qualify as the powder coating composition of this embodiment.

[0074] In this embodiment, the powder coating composition preferably contains 0.1 parts by mass or more and 10 parts by mass or less of inorganic particles (B) when the total powder coating composition is 100 parts by mass, more preferably 0.3 parts by mass or more and 8 parts by mass or less, even more preferably 0.5 parts by mass or more and 7 parts by mass or less, especially preferably 1.2 parts by mass or more and 6 parts by mass or less, and particularly preferably 2 parts by mass or more and 5 parts by mass or less. Setting the content within this range makes it easier to achieve the desired effect and to ensure the curability of the powder coating composition.

[0075] [Pigment (C)] The powder coating composition of this embodiment may further contain a pigment (C). By including a pigment (C) in the powder coating composition, it is possible to give the coating film a desired color and enhance the aesthetic appeal of the coating film. In addition, depending on the type of pigment (C), rust prevention properties can be improved.

[0076] The pigments (C) that can be used are not particularly limited. For example, known coloring pigments such as inorganic pigments and organic pigments can be used. Specifically, examples include, but are not limited to, white pigments such as titanium dioxide (e.g., CR-95 manufactured by Ishihara Sangyo Co., Ltd.), lead white, lead sulfate, lithopone, and antimony white; black pigments such as carbon black, acetylene black, lamp black, graphite, iron black (black iron oxide), and aniline black; yellow pigments such as naphthol yellow S, Hansa yellow, pigment yellow L, benzidine yellow, permanent yellow, and pyrite (yellow iron oxide); orange pigments such as chrome orange, chrome vermilion, and permanent orange; brown pigments such as iron oxide and amber; red pigments such as red iron oxide, red lead, permanent red, quinacridone-based red pigments, and diketopyrrolopyrrole-based red pigments; purple pigments such as fast violet and methyl violet lake; blue pigments such as ultramarine, Prussian blue, and indigo; and green pigments such as chrome green.

[0077] As the pigment (C), an extender pigment may be used. The extender pigments that can be used are not particularly limited, but examples include barita powder, barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, silica, white carbon, diatomaceous earth, talc, magnesium carbonate, hydrated magnesium silicate, alumina white, gloss white, mica powder, etc.

[0078] The pigment (C) is preferably one that can withstand the temperature during the baking of the paint (one that undergoes little change in color, etc., due to baking). In this respect, inorganic pigments and extender pigments are preferably used. Of course, organic pigments can also be used, provided that baking conditions and other factors are set.

[0079] Furthermore, the pigment (C) may include rust-preventive pigments known in the field of powder coatings. Examples of rust-preventive pigments include phosphate compounds, phosphate compounds, molybdenate compounds, bismuth compounds, and metal ion exchange silica.

[0080] The paint composition of this embodiment may contain only one pigment (C), or it may contain two or more pigments.

[0081] The amount of pigment (C) in the coating composition of this embodiment is not particularly limited and can be adjusted as appropriate in consideration of other performance characteristics. For example, when the total amount of the powder coating composition is 100 parts by mass, the amount of pigment (C) can be 10 to 70 parts by mass or 20 to 60 parts by mass.

[0082] [Other additives] The powder coating composition of this embodiment may contain additive components (surface modifiers) that have the effect of improving the smoothness of the coating film surface. Surface modifiers include plasticizers, silicone compounds, waxes, defoamers, leveling agents, and anti-bubble agents (components that break air trapped during painting), which are known in the field of coatings.

[0083] Examples of surface modifiers include the Acronal® series (BASF, meth)acrylic resin-based, such as Acronal 4F, the Polyflow series (Kyoeisha Chemical Co., Ltd.), the Regiflow series (ESTRON CHEMICAL), the Modaflow series (Monsanto), and benzoin.

[0084] The powder coating composition of this embodiment may contain only one surface modifier or two or more surface modifiers. Furthermore, the amount of surface modifier in the powder coating composition of this embodiment is not particularly limited and can be adjusted as appropriate in consideration of other performance characteristics.

[0085] For example, the powder coating composition of this embodiment may contain a fluidity modifier. When the powder coating composition is a powder coating composition, the fluidity of the powder can be adjusted by the fluidity modifier.

[0086] As fluidity modifiers, hydrophobic silica, hydrophilic silica, and aluminum oxide can be used. Examples of commercially available products include AEROSIL® 130, AEROSIL® 200, AEROSIL® 300, AEROSIL® R-972 (product names, all manufactured by Nippon Aerosil Co., Ltd.), and Carplex® FPS-1 (product name, manufactured by DSL).

[0087] The powder coating composition of this embodiment may contain only one type of fluidity modifier, or it may contain two or more types of fluidity modifiers. Furthermore, the amount of fluidity modifier in the powder coating composition of this embodiment is not particularly limited and can be adjusted as appropriate in consideration of other performance characteristics.

[0088] Furthermore, as other optional agents, the powder coating composition of this embodiment may also contain pigment dispersants, coupling agents, ultraviolet absorbers, light stabilizers, antioxidants, magnetic powders, charge control agents, and the like. The amounts of these agents in the powder coating composition of this embodiment are not particularly limited and can be adjusted as appropriate in consideration of other performance characteristics.

[0089] [Method for manufacturing powder coating composition] The powder coating composition of this embodiment is typically prepared by mixing a thermosetting resin (A) and inorganic particles (B). Other materials may be included in this mixture, and the details of each component are as described above.

[0090] To give a more specific example, the powder coating composition of this embodiment can be manufactured by the following procedure. (Step 1) Prepare the required amounts of each component that makes up the powder coating composition. (Step 2) Using a Henschel mixer or blender, mix each component uniformly to obtain the mixture. (Step 3) The mixture obtained in (Step 2) above is put into a kneader and melted and kneaded at 80-140°C. (Step 4) Cool the mixture obtained in (Step 3) above to 50°C or below. (Step 5) The cooled mixture is crushed using a pulverizer or the like. (Step 6) Classify the particles to achieve the desired size.

[0091] In step (4), any method of cooling can be used. For example, this could include leaving it at room temperature, using cooling rolls, or using a cooling conveyor. In step (5), the type of pulverizer used is not particularly limited and can be a mechanical type, an air-jet type, etc. Also, the pulverization may be divided into two steps, for example, coarse pulverization and fine pulverization. In step (6), a sieve or an air-jet classifier can be used for classification.

[0092] Although the above describes a method of mixing and melting all the raw materials at once, it is not always necessary to mix all the ingredients at the same time. For example, one procedure could involve first mixing and melting only a portion of the raw materials, and then adding the remaining components to the kneader. Another example is to use only a portion of the raw materials to perform steps (1) to (6) to obtain particles, then perform steps (1) to (6) with the remaining raw materials, and finally mix them using a method such as dry blending. If the remaining raw materials have a granular form (for example, individual components such as (B) and (C) mentioned above, or combinations thereof), these granular raw materials may be mixed using a method such as dry blending without performing steps (1) to (6).

[0093] Furthermore, the powder coating composition obtained in this manner preferably has a median diameter of 10 μm to 70 μm, more preferably 15 μm to 65 μm, and even more preferably 20 μm to 60 μm. Setting the median diameter of the particles constituting the powder coating composition to such a value makes it easier to improve handling. An example of a measuring device that can be used to measure this median diameter is the particle distribution analyzer MT3000II (manufactured by Microtrac-Bell Co., Ltd.).

[0094] [Application] The powder coating composition of this embodiment is used, for example, to form a cured coating film. This cured coating film is formed by curing the powder coating composition and exhibits various functions. Typically, this cured coating film has an inactivating effect on various viruses.

[0095] This virus may or may not have an envelope. Enveloped viruses include herpes simplex virus type 1, herpes simplex virus type 2, varicella-zoster virus, cytomegalovirus, rubella virus, measles virus, mumps virus, influenza A virus, influenza B virus, influenza C virus, Japanese encephalitis virus, Epstein-Barr virus, hepatitis B virus, Zika virus, Ebola virus, human immunodeficiency virus, respiratory syncytial virus (RSV), and coronaviruses. Examples of viruses that do not have an envelope include adenoviruses, papillomaviruses such as human papillomavirus, picornaviruses such as poliovirus and hepatitis A virus, caliciviruses such as norovirus and feline calicivirus, and reoviruses such as rotavirus.

[0096] Furthermore, the powder coating composition of this embodiment can provide articles equipped with the aforementioned cured coating film. Specific examples of such articles include furniture, lighting fixtures, electrical panels, agricultural machinery, gas cylinders, road materials, machine tools, and medical equipment. In particular, providing an antiviral coating film on the surface of articles that people directly touch can prevent infection through contact. The thickness of the cured coating film can be appropriately adjusted, for example, between 20 and 150 μm.

[0097] The method for manufacturing such articles is described below. First, the powder coating composition of this embodiment is baked onto the surface of an article. That is, the powder coating composition is applied to the surface of an article (typically a metal article), and heated to melt the powder coating composition, thereby forming a cured coating film. The heating conditions can be, for example, 120 to 250°C for 5 to 60 minutes. Regarding the specific method of forming the coating film, known technologies in the field of powder coatings can be used as appropriate. Examples include electrostatic powder spraying, fluidized bed immersion, and electrostatic fluidized bed immersion.

[0098] Furthermore, they may be provided in the following embodiments. The powder coating composition wherein the inorganic particles (B) are particles on which the metal or metal ions are supported on a carrier. The powder coating composition wherein the carrier is one selected from the group consisting of zeolite, silica gel, glass, alumina, activated carbon, and titania. The powder coating composition wherein the median diameter of all particles constituting the powder coating composition is 10 μm or more and 70 μm or less. The powder coating composition wherein, when the total amount of the powder coating composition is 100 parts by mass, the content of the inorganic particles (B) is 0.1 parts by mass or more and 10 parts by mass or less. The powder coating composition wherein the thermosetting resin (A) comprises a polyester resin. The powder coating composition wherein the thermosetting resin (A) comprises either a combination of a polyester resin having a carboxyl group and a β-hydroxyalkylamide compound, or a combination of a polyester resin having a hydroxyl group and an isocyanate compound. The powder coating composition wherein the thermosetting resin (A) comprises an epoxy resin. A powder coating composition further comprising a pigment (C). A cured coating film, wherein the powder coating composition is cured. An article comprising the cured coating film. A method for producing a powder coating composition, comprising the step of mixing a thermosetting resin (A) and inorganic particles (B), wherein the inorganic particles (B) contain one or more metals or metal ions selected from the group consisting of silver, copper, cobalt, nickel, and zinc, and the particles have a median diameter of 10 μm or more and 100 μm or less. Of course, this is not always the case.

[0099] Although embodiments of the present invention have been described above, these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0100] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

[0101] [Raw materials used] First, the raw materials used in this embodiment will be described. The various raw materials used in this embodiment are as follows:

[0102] (Thermosetting resin (A)) • A-1: ​​Carboxylated polyester resin (Product name: CRYLCOAT® 2661-3, manufactured by Daicel Ornex Co., Ltd., acid value 33 mg KOH / g) • A-2: β-hydroxyalkylamide compound (Trade name: Primid(registered trademark) XL-552, manufactured by EMS-CHEMIE AG, Compound name: N,N,N',N'-tetrakis-(2-hydroxyethyl)-azipamide, Hydroxyl value 600-725 mgKOH / g, Contains 4 β-hydroxyalkylamide groups per molecule) • A-3: Hydroxyl-terminated polyester resin (Product name: CRYLCOAT® 2890-0, manufactured by Daicel Ornex Co., Ltd., 30 mg KOH per g of hydroxyl group) • A-4: Blocked isocyanate (Trade name: VESTAGON® B1530, manufactured by Evonik, polyisocyanate of ε-caprolactam block with an isocyanate (NCO) equivalent of 273.6) • A-5: Carboxylated polyester resin (Product name: GV-235, manufactured by Nippon Yupika Co., Ltd., acid value 39 mg KOH / g) • A-6: Epoxy resin (Product name: jER(registered trademark)1002, manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin)

[0103] (Inorganic particles containing silver (B)) • B-1: Silver-supported zeolite (median diameter: 59.2 μm) • B-2: Silver-supported zeolite (median diameter: 40 μm) • B'-1: Silver-supported zeolite (Product name: Zeomic LG10D-CP, manufactured by Sinanen Zeomic Co., Ltd., median diameter: 8.9 μm) • B'-2: Inorganic silver-based particles (Product name: Neosynthol AV-18, manufactured by Sumika Environmental Science Co., Ltd., median diameter: 5.8 μm)

[0104] (Pigment (C)) • C-1: Titanium dioxide (product name: CR-95, manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.28 μm)

[0105] (Additives) • X-1: Surface modifier (Acronal 4F) (Product name: Acronal (registered trademark) 4F, manufactured by BASF, (meth)acrylic resin type) • X-2: Surface preparation agent (benzoin) (Product name: Benzoin, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) • X-3: Tin catalyst (Product name: TN-12, manufactured by Sakai Chemical Industry Co., Ltd., Compound name: Dibutyltin laurate) • X-4: Imidazole-based curing agent (Product name: Curazol C-17 Z, manufactured by Shikoku Chemicals Co., Ltd., compound name: 2-heptadecylimidazole)

[0106] Furthermore, the median diameter of the aforementioned (silver-containing inorganic particles (B)) was measured using the particle distribution analyzer MT3000II (manufactured by Microtrac-Bell Corporation).

[0107] [Preparation of powder coating compositions] The powder coating compositions for each example and each comparative example were prepared using the methods described below.

[0108] Each component shown in Table 1 (in the table, the numerical value for each component represents the formulation amount (parts by mass) as the active ingredient) was mixed in a Henschel mixer to obtain a mixture. The obtained mixture was placed in a kneader (product name: Busco Kneader PR46, manufactured by Buss AG) and melt-kneaded at 100°C to obtain a kneaded product. The obtained kneaded product was cooled to below 50°C, then finely ground using a hammer-type impact pulverizer, and classified using a 150-mesh sieve to obtain each powder coating composition. The median diameter of the entire powder coating composition (the median diameter of all particles constituting the powder coating composition) in each example and comparative example was in the range of 35 to 45 μm.

[0109] [evaluation] Each powder coating composition prepared as described above was applied to the surface of a commercially available cold-rolled steel sheet (product name: SPCC-SD, manufactured by Nippon Test Panel Co., Ltd., 50 mm wide x 50 mm long x 0.8 mm thick) using a corona-charging electrostatic powder coating machine (product name: PG-1, manufactured by Asahi Sanac Co., Ltd.) at a coating voltage of -60 kV. The sheets were then baked at a predetermined temperature for 20 minutes. Afterward, the sheets were allowed to cool to room temperature to obtain steel sheets with a coating film thickness of approximately 60 μm (hereinafter referred to as "test sheets"). The antiviral activity of these test sheets was evaluated under the following conditions. For the powder coating compositions of Examples 4 and 5, a curing condition of 180°C was used, while for the other powder coating compositions, a curing condition of 160°C was used.

[0110] <Antiviral activity evaluation (influenza virus)> In accordance with ISO21702, a virus suspension of the specified concentration was obtained by infecting host cells (MDCK cells: canine kidney-derived cells) with influenza virus (Influenza A virus (H3N2): A / Hong Kong / 8 / 68; TC adapted ATCC VR-1679) and culturing them. 0.4 ml of the obtained virus suspension was dropped onto the test plate prepared as described above, and the plate was covered with a 4 cm square polyethylene film to ensure that the virus suspension was distributed across the entire surface of the test plate. The test plate, with the virus suspension distributed across its entire surface in this manner, was left to stand for 24 hours at a temperature of 25°C. Subsequently, the polyethylene film was peeled off the test plate, and both the test plate and the polyethylene film were washed with SCDLP medium. The wash solutions were then progressively diluted with EMEM medium. Each diluted wash solution was inoculated into host cells cultured in a monolayer on a culture plate, and the host cells were cultured on each culture plate. Subsequently, the culture plates containing the host cells were stained, and the viral infectivity titer (PFU / sample) was determined by counting the formed plaques.

[0111] For control, the viral infectivity titer (PFU / sample) was calculated for polyethylene film cut into 5cm squares, in the same manner as the test board.

[0112] The antiviral activity value was calculated using the following formula based on the viral infectivity titer of each obtained sample. R = Ut - At R: Antiviral activity level Ut: Mean of the common logarithm of the viral infectivity titer (PFU / sample) after 24 hours of standing in the control (polyethylene film). At: Mean of the common logarithm of the viral infectivity titer (PFU / sample) after 24 hours of standing on the test plate.

[0113] The antiviral activity value is the difference between the average common logarithm of the viral infectivity titer of the control (polyethylene film) and the average common logarithm of the viral infectivity titer of the test board. Therefore, a higher antiviral activity value indicates better antiviral activity of the coating formed on the surface of the test board.

[0114] <Antiviral activity evaluation (feline calicivirus)> Regarding the <evaluation of antiviral activity (influenza virus)> mentioned above, the antiviral activity of the coating film was evaluated using the same method as above, except that a predetermined concentration of virus suspension was obtained by infecting host cells (CRFK cells: cat kidney-derived cells) with feline calicivirus (Feline caliciVirus: Strain: F-9 ATCC VR-782) and culturing them.

[0115] <Antiviral activity evaluation (after water resistance test)> The obtained test panels were evaluated for the durability (water resistance) of the coating film in accordance with "Category 1" of "3. Durability Test Method (2021 Edition)" of the Japan Society for Antimicrobial Articles Technology (SIAA). Specifically, the obtained test panels were immersed in deionized water at room temperature (20°C) for 16 hours, then the moisture was wiped off with Kimwipes, and the same evaluation as described above for <Antiviral Activity Evaluation (Influenza Virus)> and <Antiviral Activity Evaluation (Feline Calicivirus)> was performed. In this section, each evaluation was performed on the same day after wiping off the moisture from the test panels. In the table, "-" indicates that the test results were judged to be unsatisfactory before the water resistance test was performed, and therefore the evaluation after the water resistance test was not carried out.

[0116] Table 1 shows the evaluation results of the antiviral activity values ​​for each sample.

[0117] [Table 1]

[0118] As shown in Table 1, the powder coating compositions of each example provide a coating film in which the desired function (antiviral activity in this example) is sustainably exhibited at a high level.

Claims

1. A powder coating composition, It comprises a thermosetting resin (A) and inorganic particles (B), The inorganic particles (B) are a powder coating composition comprising one or more metals or metal ions selected from the group consisting of silver, copper, cobalt, nickel, and zinc, and having a median diameter of 10 μm or more and 100 μm or less.

2. In the powder coating composition according to claim 1, The inorganic particles (B) are particles on which the metal or metal ions are supported on a carrier, in a powder coating composition.

3. In the powder coating composition according to claim 2, The aforementioned carrier is one selected from the group consisting of zeolite, silica gel, glass, alumina, activated carbon, and titania, in a powder coating composition.

4. In the powder coating composition according to any one of claims 1 to 3, A powder coating composition wherein the median diameter of all particles constituting the powder coating composition is 10 μm or more and 70 μm or less.

5. In the powder coating composition according to any one of claims 1 to 4, A powder coating composition in which, when the total amount of the powder coating composition is 100 parts by mass, the content of the inorganic particles (B) is 0.1 parts by mass or more and 10 parts by mass or less.

6. In the powder coating composition according to any one of claims 1 to 5, The thermosetting resin (A) is a powder coating composition containing a polyester resin.

7. In the powder coating composition according to claim 6, The thermosetting resin (A) is A combination of a polyester resin having a carboxyl group and a β-hydroxyalkylamide compound; and A combination of a polyester resin having hydroxyl groups and an isocyanate compound; A powder coating composition comprising any of the following.

8. In the powder coating composition according to any one of claims 1 to 7, The thermosetting resin (A) is a powder coating composition containing an epoxy resin.

9. In the powder coating composition according to any one of claims 1 to 8, A powder coating composition further containing a pigment (C).

10. A cured coating film, A cured coating film obtained by curing the powder coating composition according to any one of claims 1 to 9.

11. Articles, An article comprising the cured coating film described in claim 10.

12. A method for manufacturing a powder coating composition, The process includes a step of mixing a thermosetting resin (A) and inorganic particles (B), A method for producing a powder coating composition, wherein the inorganic particles (B) contain one or more metals or metal ions selected from the group consisting of silver, copper, cobalt, nickel, and zinc, and the particles have a median diameter of 10 μm or more and 100 μm or less.

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