JP7794040B2 - Antibacterial and antiviral coating agent, antibacterial and antiviral printed matter, and method for producing the same - Google Patents

Description

The present invention relates to an antibacterial and antiviral coating agent and a printed material having an antibacterial and antiviral coating layer formed therefrom.

With growing awareness of hygiene in recent years, antibacterial agents, antiviral agents, antifungal agents, disinfectants, etc. are being used to prevent the spread of bacteria, mold, and other infections in food and pharmaceutical factories, buildings such as hospitals and nursing homes, food and kitchen utensils, medical instruments, medical equipment, and even general household products. However, with the recent emergence of various infectious diseases, there has been a particular increase in interest in preventing infection from bacteria and viruses. Therefore, there is a demand for technology that can impart antibacterial and antiviral properties to various components, not only in public facilities but also in general homes.

In conventional technology, organic or inorganic antibacterial agents have been proposed to solve these problems. For example, organic iodine-based antibacterial agents, pyridine-based antibacterial agents, haloalkylthio-based antibacterial agents, thiazole-based antibacterial agents, benzimidazole-based antibacterial agents, isophthalonitrile-based antibacterial agents, phenol-based antibacterial agents, triazine-based antibacterial agents, bromine-based antibacterial agents, quaternary ammonium salt-based antibacterial agents, organometallic antibacterial agents, and antibacterial materials in which metal ions are supported on substances such as zeolite or silica gel have been developed, and antibacterial coatings using these have been developed (Patent Documents 1 to 3). However, the variety of compounds that exhibit antibacterial properties is limited, and new materials that exhibit antibacterial properties, and preferably antiviral properties as well, are needed. However, coated objects with these coatings often show poor durability of their effectiveness after repeated touch and rubbing in daily life. Furthermore, even if antibacterial properties are exhibited, there are cases in which the physical properties of the ink film are affected.

Patent No. 6801137 Japanese Patent Application Laid-Open No. 2017-39905 JP 2017-137481 A

The object of the present invention is to provide a coating agent that has good antibacterial and antiviral properties, as well as good substrate adhesion, abrasion resistance, heat resistance, blocking resistance, and curling suitability, and that retains its antibacterial and antiviral properties even after the coating layer is subjected to friction and heat history after application.

After extensive research, the inventors discovered that the above problems could be solved by using the "antibacterial and antiviral coating agent" described below, leading to the completion of the present invention.

That is, the present invention provides an antibacterial and antiviral coating agent containing a urethane resin, a nitrocellulose resin, an organic solvent, a plasticizer, and inorganic particles,
The present invention relates to an antibacterial and antiviral coating agent, wherein the plasticizer includes at least one selected from the group consisting of citrate esters, phthalate esters, phosphate esters, trimellitates, aliphatic dibasic acid esters, and sulfonate amides, and the inorganic particles include silver-based inorganic particles.

The present invention also relates to the above antibacterial and antiviral coating agent, in which the silver-based inorganic particles are silver-zirconium phosphate particles, and the coating agent contains 0.05 to 0.9 mass% of the silver-zirconium phosphate particles based on the total mass of the coating agent.

The present invention also relates to the above antibacterial and antiviral coating agent, in which the silver-based inorganic particles are silver-zinc calcium phosphate particles, and the coating agent contains 0.5 to 9 mass% of the silver-zinc calcium phosphate particles based on the total mass of the coating agent.

The present invention also relates to the above antibacterial and antiviral coating agent, in which the inorganic particles have an average particle size of 0.5 to 10 μm.

The present invention also relates to the above antibacterial and antiviral coating agent, in which the mass ratio of urethane resin to nitrocellulose resin is 2/98 to 50/50 by mass.

The present invention also relates to the above-mentioned antibacterial and antiviral coating agent, which further contains an extender pigment and/or resin microparticles.

The present invention also relates to the above antibacterial and antiviral coating agent, in which the mass ratio of urethane resin to nitrocellulose resin is 98/2 to 50/50 by mass.

The present invention also relates to the above-mentioned antibacterial and antiviral coating agent for use in flexographic printing.

The present invention also relates to an antibacterial and antiviral printed material having an antibacterial and antiviral coating layer formed from the above-mentioned antibacterial and antiviral coating agent on a substrate.

The present invention also relates to a method for producing an antibacterial and antiviral printed matter, which includes a step of flexographically printing an antibacterial and antiviral coating agent onto a plastic substrate, wherein the antibacterial and antiviral coating agent contains a urethane resin, a nitrocellulose resin, an organic solvent, a plasticizer, and inorganic particles, the plasticizer contains at least one selected from the group consisting of citrate esters, phthalate esters, phosphate esters, trimellitates, aliphatic dibasic acid esters, and sulfonate amides, and the inorganic particles contain silver-based inorganic particles.

The present invention makes it possible to provide a coating agent that has good antibacterial and antiviral properties, as well as excellent substrate adhesion, abrasion resistance, heat resistance, blocking resistance, and curling suitability, and that retains antibacterial and antiviral properties even after the coating layer has been subjected to friction and heat history after application.

The following describes an embodiment of the present invention. The following description of the components is one example (representative example) of an embodiment of the present invention, and the present invention is not limited to these details as long as it does not deviate from the spirit of the invention.

In the following description, the antibacterial and antiviral coating agent may be simply referred to as a "coating agent," but this is the same thing. A layer formed from the antibacterial and antiviral coating agent by printing or other means will be referred to as an "antibacterial and antiviral coating layer" or "coating layer," but this is the same thing.

The components that make up the antibacterial and antiviral coating agent of the present invention are described in detail below.

The present invention relates to an antibacterial and antiviral coating agent containing a urethane resin, a nitrocellulose resin, an organic solvent, a plasticizer, and antibacterial particles, wherein the plasticizer is at least one selected from the group consisting of citrate esters, phthalate esters, phosphate esters, trimellitates, aliphatic dibasic acid esters, and sulfonamides, and the antibacterial particles contain silver-based inorganic particles. Coating agents that use nitrocellulose tend to harden the coating layer, but the use of the above-mentioned plasticizer softens the coating, allowing the silver-based inorganic particles to remain stable, resulting in the development of antibacterial and antiviral properties. At the same time, the physical properties of the coating can also be favorably maintained and improved.

<Binder resins such as urethane resins and nitrocellulose resins>
The urethane resin and nitrocellulose resin function as binder resins. The total amount of urethane resin and nitrocellulose resin is preferably 60% by mass. A content of 80% by mass is even more preferable. This is because it improves adhesion to the substrate. Furthermore, the mass ratio of urethane resin to nitrocellulose resin is preferably 2/98 to 50/50, respectively. More preferably, it is 5/95 to 40/60 or 5/95 to 30/70, respectively. With this blending ratio and combination, the use of a plasticizer, described below, in combination improves the adhesion and curl resistance of the printed layer.

On the other hand, when extender pigments and/or resin microparticles are used as matting agents, the mass ratio of urethane resin to nitrocellulose resin is preferably 98/2 to 50/50 by mass. A mass ratio of 95/5 to 60/40 or 95/5 to 70/30 is more preferred. In this case, reverse gloss, heat resistance, and substrate adhesion are improved.

Furthermore, the resin may contain, but is not limited to, vinyl chloride-acrylic copolymer resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, acrylic resin, styrene resin, styrene-maleic acid copolymer resin, dammar resin, ketone resin, and cyclized rubber.

<Urethane resin>
The urethane resin preferably has a weight-average molecular weight of 8,000 to 80,000, and more preferably 10,000 to 60,000. The glass transition temperature is preferably 0°C or lower. It is more preferably -40°C to -5°C, and even more preferably -35°C to -10°C. This is because it provides good affinity with the nitrocellulose resin and the plasticizer. Furthermore, the urethane resin preferably has an amine value and/or a hydroxyl value, with the amine value preferably being 0.5 to 20 mgKOH/g, and more preferably being 1 to 15 mgKOH/g. Furthermore, the hydroxyl value is preferably 0.5 to 30 mgKOH/g, and more preferably being 1 to 20 mgKOH/g. Within the above ranges, adhesion to the substrate is improved, and the resin is more likely to exhibit antibacterial and antiviral properties through interaction with the silver-based inorganic particles.

The urethane resin preferably contains structural units derived from polyether polyol and/or polyester polyol (including polylactone polyol), and the total content thereof is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and even more preferably 10 to 50% by mass, based on 100% by mass of the urethane resin solids.

There are no particular restrictions on the urethane resin, and it can be produced using any known method. Preferred examples include urethane resins made from polyol and polyisocyanate, and urethane resins obtained by reacting a urethane prepolymer made from polyol and polyisocyanate and having a terminal isocyanate with a polyamine. Examples of production methods include the method described in JP 2013-256551 A.

Examples of polyols include polyester polyols (including polylactone polyols), polyether polyols, polycarbonate polyols, polyolefin polyols, castor oil polyols, hydrogenated castor oil polyols, dimer diols, and hydrogenated dimer diols. Preferably, polyether polyols and/or polyester polyols (including polylactone polyols) are used.

Suitable examples of polyether polyols include polypropylene glycol, polyethylene glycol, polytetramethylene glycol, polytrimethylene glycol, and polyether polyols, which are copolymers selected from these. The average molecular weight of polyether polyols is preferably 200 to 5000. The number average molecular weight is calculated from the hydroxyl value, assuming the terminal hydroxyl groups, using Equation 1: (Equation 1) Number average molecular weight of polyol = 1000 x 56.1 x hydroxyl group valence / hydroxyl value

Examples of polyester polyols include condensates obtained by the esterification reaction of polybasic acids and diols, and polylactone polyols. Polylactone polyols are formed by dehydration condensation of hydroxyl groups and carboxyl groups in the same molecule, where the lactone is a cyclic ester. Suitable examples of polylactone polyols include those obtained by ring-opening polymerization of lactone with a diol as an initiator. Suitable examples of such lactones include α-acetolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone. Diols similar to those described below can be used. In the polyester polyol, which is a condensate obtained by an esterification reaction of a polybasic acid and a diol, the polybasic acid is preferably a dibasic acid, and examples of the dibasic acid include adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, glutaric acid, 1,4-cyclohexyldicarboxylic acid, dimer acid, and hydrogenated dimer acid. Examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3,5-trimethylpentanediol, 2,4-diethyl-1,5-pentanediol, 1,12-octadecanediol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride, 2-monoglyceride, 1-monoglycerin ether, 2-monoglycerin ether, dimer diol, and hydrogenated dimer diol.

Among diols, diols with a branched structure are preferred. A branched structure refers to a diol with an alkyl side chain in which at least one hydrogen atom of the alkylene group contained in the diol is replaced with an alkyl group. Examples include propylene glycol, 1,3-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,4-pentanediol, 3-methyl-1,5-pentanediol, 2,5-hexanediol, 2-methyl-1,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol. These are particularly preferred because they improve printability, printing effects, and blocking resistance. These polyester polyols can be used alone or in combination. As dibasic acids, sebacic acid and adipic acid are particularly preferred. Polyols having three or more hydroxyl groups and polycarboxylic acids having three or more carboxyl groups can also be used in combination.

The number average molecular weight of the polyester polyol is preferably 200 to 5,000. The number average molecular weight can be calculated using the above-mentioned (Equation 1).

The polyisocyanates mentioned above include various known aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates commonly used in the production of urethane resins. These may also form trimers to form an isocyanurate ring structure. Examples of aromatic diisocyanates include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, and tolylene diisocyanate. Examples of aliphatic diisocyanates include butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, etc. Examples of alicyclic diisocyanates include cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, hydrogenated 4,4-diphenylmethane diisocyanate, and dimer diisocyanate in which the carboxyl group of a dimer acid is converted into an isocyanate group. Among these, at least one selected from tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, bis(isocyanatomethyl)cyclohexane, hexamethylene diisocyanate, and a trimer of hexamethylene diisocyanate is preferred. These polyisocyanates can be used alone or in combination of two or more.

Polyamines preferably have a molecular weight of 500 or less, but are not limited to the following. Examples include diamines and polyfunctional amines. Examples include diamine chain extenders such as ethylenediamine, propylenediamine, hexamethylenediamine, pentamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and p-phenylenediamine. Hydroxylated diamine chain extenders such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine can also be used. These chain extenders can be used alone or in combination of two or more. Trifunctional or higher polyfunctional amine chain extenders can also be used if necessary. Specific examples include diethylenetriamine, iminobispropylamine (IBPA, 3,3'-diaminodipropylamine), triethylenetetramine, N-(3-aminopropyl)butane-1,4-diamine (spermidine), 6,6-iminodihexylamine, 3,7-diazanonane-1,9-diamine, and N,N'-bis(3-aminopropyl)ethylenediamine. Of these, isophoronediamine, hexamethylenediamine, and iminobispropylamine are preferred.

The polyamine may contain a compound containing a primary or secondary monovalent amino group. These compounds function as a polymerization terminator to stop excessive reaction. Examples of such compounds include dialkylamines such as di-n-butylamine and amino alcohols such as 2-ethanolamine. Furthermore, when it is particularly desired to introduce carboxyl groups into the urethane resin, amino acids such as glycine and L-alanine can be used as polymerization terminators. When using a polymerization terminator, the chain extension reaction may be carried out using the polymerization terminator and a chain extender together, or the polymerization may be terminated by adding the polymerization terminator alone after a certain amount of chain extension reaction has been carried out using the chain extender. While molecular weight control is possible without using a polymerization terminator, in this case, adding the prepolymer to a solution containing the chain extender is preferable from the standpoint of reaction control.

(nitrocellulose resin)
Nitrocellulose resins are preferably obtained by reacting native cellulose with nitric acid to replace three hydroxyl groups in the six-membered ring of the anhydroglucopyranose group in the native cellulose with nitric acid groups to form nitrate esters. The weight-average molecular weight is preferably 5,000 to 200,000, more preferably 10,000 to 100,000. Furthermore, the glass transition temperature is preferably 120°C to 170°C or 140°C to 165°C. The nitrogen content is preferably 10.5 to 12.5% by mass. While the glass transition temperature of nitrocellulose resins often appears in two places, the higher glass transition temperature is defined as the higher one. The above range is preferred because it improves the strength of the ink film and enhances its abrasion resistance and knead resistance. It is also preferred because it improves solubility in solvents, low-temperature ink stability, and compatibility with co-polymer resins. When used in combination with a urethane resin and a plasticizer, nitrocellulose resins enhance thermoplasticity and provide a stable coating layer.

<Organic solvent>
The coating agent used in the present invention preferably contains an organic solvent. Examples of the organic solvent include alcohol-based solvents such as methanol, ethanol, isopropanol, and normal propyl alcohol, ester-based solvents such as ethyl acetate and normal propyl acetate, glycol ether-based solvents such as propylene glycol monomethyl ether, ketone-based solvents such as acetone and methyl ethyl ketone, aromatic solvents such as toluene and xylene, and mixtures thereof. Among these, it is preferable to include normal propyl alcohol or normal propyl acetate.

<Plasticizer>
The antibacterial and antiviral coating agent of the present invention preferably contains a plasticizer in view of the properties of the film formed from the coating agent. The plasticizer must be at least one selected from citrate esters, phthalate esters, phosphate esters, trimellitates, aliphatic dibasic acid esters, and sulfonic acid amides, with trimellitates and citrate esters being preferred. Of these, citrate esters are even more preferred. The amount of plasticizer contained is preferably 0.1 to 8 mass% of the total mass of the coating agent, more preferably 0.5 to 5 mass%, and even more preferably 1 to 3 mass%. Preferred citrate esters include acetyltrialkyl citrates such as triethyl citrate, acetyltriethyl citrate, tri-n-butyl citrate, acetyltri-n-butyl citrate, and acetylcitrate-2-ethylhexyl. The alkyl group preferably has 2 to 12 carbon atoms. Among these, acetyltri-n-butyl citrate and acetyltriethyl citrate are preferred. Examples of phthalate esters include dialkyl phthalates such as bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, and diundecyl phthalate, and the alkyl group preferably has 2 to 12 carbon atoms. Of these, diisononyl phthalate and diisodecyl phthalate are preferred. Examples of phosphate esters include tricresyl phosphate, triphenyl phosphate, and tributyl phosphate, with tributyl phosphate being preferred. Examples of trimellitate esters include trialkyl trimellitates such as tri-2-ethylhexyl trimellitate, trioctyl trimellitate, and triisononyl trimellitate, and the alkyl group preferably has 2 to 12 carbon atoms. Of these, tri-2-ethylhexyl trimellitate is preferred. As the aliphatic dibasic acid ester, a fatty acid dialkyl ester is preferred, and suitable examples thereof include adipate esters and sebacate esters, and suitable examples thereof include sebacate dialkyl esters such as bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis(2-ethylhexyl) sebacate, diisononyl sebacate, and diisodecyl sebacate, and the alkyl group preferably has 2 to 12 carbon atoms. As the sulfonic acid amide, N-butylbenzenesulfonic acid amide, N-ethyltoluenesulfonic acid amide, and the like are preferred.

<Inorganic particles, silver-based inorganic particles>
Silver-based inorganic particles and other inorganic particles are used to exhibit antibacterial/antiviral properties. Being silver-based inorganic particles allows the antibacterial/antiviral properties to be exhibited. On the other hand, when the coating layer has thermoplasticity due to a plasticizer, rather than when the particles are present alone in the coating layer, this is preferable because it can enhance not only the antibacterial/antiviral properties but also the substrate adhesion, abrasion resistance, and the like. The silver-based inorganic particles preferably include silver-zirconium phosphate particles and/or silver-zinc calcium phosphate particles.

In the present invention, the average particle size (dispersion average particle size) refers to the D50 measurement value obtained by the laser diffraction/scattering method, and can be measured using, for example, a particle size distribution measuring device manufactured by Microtrac-Bell, such as the Microtrac MT3000II series.

<Silver-zirconium phosphate particles>
Silver-zirconium phosphate particles are made by supporting silver ions on hexagonal zirconium phosphate, an inorganic ion exchanger, by ion exchange, and comprise oxygen octahedra centered on zirconium and oxygen tetrahedra centered on phosphorus, which are connected three-dimensionally with oxygen sharing, with silver ions present in the framework. Specific products include Novalon AG300 (Toagosei Co., Ltd.), Novalon AG1100 (Toagosei Co., Ltd.), Novalon AGZ330 (Toagosei Co., Ltd.), and Novalon AGT330 (Toagosei Co., Ltd.).

The average particle size of the silver-zirconium phosphate particles is preferably 0.4 to 12 μm, and more preferably 0.7 to 4 μm. The specific gravity of the silver-zirconium phosphate particles is preferably 1 to 7, and more preferably 2 to 5. The apparent specific gravity (bulk specific gravity) of the silver-zirconium phosphate particles is preferably 0.05 to 1, more preferably 0.05 to 0.7, and even more preferably 0.1 to 0.4.

<Silver-zinc calcium phosphate particles>
The silver-zinc calcium phosphate particles are made of zeolite carrying silver, and the zeolite contains zinc calcium phosphate. The average particle size of the silver-zinc calcium phosphate particles is preferably 1.0 to 8.0 μm, more preferably 2.0 to 6.0 μm. The specific gravity of the silver-zinc calcium phosphate particles is preferably 0.1 to 8, more preferably 1.0 to 3.

The antibacterial and antiviral coating agent of the present invention preferably further contains an extender pigment and/or resin microparticles. By including an extender pigment and/or resin microparticles in the antibacterial and antiviral coating agent, a matte finish and negative gloss can be imparted. From the perspective of further improving the matte finish and antibacterial properties, it is even more preferable to include an extender pigment and resin microparticles.

When the antibacterial and antiviral coating agent of the present invention contains a body pigment and resin microparticles, the mass ratio of the body pigment to the resin microparticles is preferably 90:10 to 15:85, more preferably 85:15 to 25:75, and even more preferably 75:25 to 40:60. This is to improve matte finish and reverse gloss. When both the body pigment and the resin microparticles are contained, their total content is preferably 18 to 42 mass%, and even more preferably 24 to 36 mass%, based on 100 mass% of the antibacterial and antiviral coating agent.

<Extender pigment>
When the antibacterial and antiviral coating agent of the present invention contains a body pigment, the content of the body pigment is preferably 0.2 to 40 mass% and more preferably 9 to 25 mass% relative to 100 mass% of the antibacterial and antiviral coating agent. Preferred body pigments include silica, barium sulfate, kaolin, clay, calcium carbonate, and magnesium carbonate, with barium sulfate being more preferred. This is to improve blocking resistance and prevent the antibacterial agent from being released.

<Resin fine particles>
In the coating agent of the present invention, the resin particles can control the light diffusion property by their inherent refractive index, and can impart desired design properties such as gloss, matte finish, and transparency.
When the antibacterial and antiviral coating agent of the present invention contains resin microparticles, the refractive index of the resin microparticles used is preferably 1.40 or higher, more preferably 1.45 or higher. It is also preferably 1.75 or lower, more preferably 1.70 or lower, and even more preferably 1.60 or lower. Examples of the resin microparticles include acrylic microparticles, polyamino microparticles, polyolefin microparticles, and polystyrene microparticles. It is preferable to contain at least one type of microparticle selected from the above. Of these, acrylic microparticles are preferred. The average particle diameter of the resin microparticles is preferably 0.5 to 10 μm, more preferably 1 to 8 μm, and even more preferably 1.5 to 6 μm. This is to improve abrasion resistance and matte effect.

The content of resin microparticles in the total mass of non-volatile components of the coating agent is preferably in the range of 5 to 25 mass%, depending on the desired degree of slip (abrasion resistance) and matte effect, the particle size and type of resin microparticles added, etc. 9 to 17 mass% is even more preferable. The resin microparticles preferably comprise 3 to 30 mass%, more preferably 6 to 25 mass%, and even more preferably 7 to 20 mass%, of the total mass of the coating agent.

Examples of such resin microparticles include polyacrylic microparticles such as the Art Pearl GS series and Art Pearl J series manufactured by Negami Chemical Industrial Co., Ltd., polyamino microparticles such as the Optobeads series manufactured by Nissan Chemical Industries, Ltd., polyolefin microparticles such as the Flowbeads LE series manufactured by Sumitomo Seika Chemical Co., Ltd., and polystyrene resin microparticles such as the Fine Powder MP series manufactured by Soken Chemical & Engineering Co., Ltd. and the Techpolymer SBX series and Techpolymer SSX series manufactured by Sekisui Chemical Co., Ltd.

<Other additives>
The coating agent of the present invention may also contain, as necessary, dispersants, ultraviolet absorbers, light stabilizers, antibacterial and antifungal agents, antistatic agents, antioxidants, colorants, lubricants, fillers, latent curing agents, flame retardants, curing agents, etc.

<Production of Coating Agent>
The coating agent of the present invention can be produced, for example, by dissolving and/or dispersing a urethane resin, a nitrocellulose resin, an organic solvent, a plasticizer, and antibacterial particles, and optionally an extender pigment, in an organic solvent. Specifically, for example, the antibacterial particles are mixed with a nitrocellulose resin and, optionally, a urethane resin, and dispersed in an organic solvent to produce a dispersion. The resulting dispersion can then be further blended with a nitrocellulose resin, a plasticizer, or, optionally, other resins or additives to produce the coating agent. The particle size distribution of the dispersion can be adjusted by appropriately adjusting the size of the grinding media in the disperser, the grinding media filling rate, the dispersion treatment time, the dispersion discharge rate, the dispersion viscosity, and the like. Commonly used dispersers, such as roller mills, ball mills, pebble mills, attritors, and sand mills, can be suitably used.

<Antibacterial and antiviral printed materials>
Furthermore, antibacterial and antiviral printed matter is formed by printing and applying the antibacterial and antiviral coating agent onto a substrate. Rotary printing methods such as gravure printing and flexographic printing are preferred as the printing and application method. Flexographic printing is preferred from the viewpoint of the printed film thickness described below. An antibacterial and antiviral printed matter can be produced by flexographically printing the coating agent onto a substrate to form a coating layer on the substrate. A preferred embodiment of the printed matter has a pattern layer formed from printing ink between the substrate and the coating layer. The coating layer is preferably positioned as a surface protective layer. Other layers include a primer layer, a pattern layer and a thermoplastic resin layer, an anchor coating layer, etc.

<Coating layer>
By using the antibacterial and antiviral agent in combination with the binder resin and a plasticizer, the coating layer becomes softer, allowing for greater flexibility in the coating film. This inevitably prevents the antibacterial and antiviral agent from being embedded in the coating film, inhibiting the expression of antibacterial and antiviral properties, and from being removed from the coating layer after rubbing, etc., making it easier to maintain antibacterial and antiviral performance. Therefore, taking into account the average particle size of the inorganic particles, the coating layer thickness is preferably 0.5 to 5 μm, and more preferably 1 to 3 μm. The amount of antibacterial and antiviral agent added to the coating layer is preferably 0.01 to 2 mass% in terms of solids content, and more preferably 0.1 to 1 mass%.

<Flexographic printing> (flexographic plate)
Plates used in the above-mentioned flexographic printing include photosensitive resin plates that utilize ultraviolet curing using a UV light source and elastomer material plates that use a direct laser engraving method. Regardless of the method for forming the image area of the flexographic plate, a plate with a screen ruling of 75 lpi or more is used. Any sleeve or cushion tape can be used for attaching the plate. (Printing Press) Flexographic printing presses include CI-type multicolor flexographic printing presses and unit-type multicolor flexographic printing presses, and ink supply methods such as chamber methods and two-roll methods can be used, and an appropriate printing press can be used.

<Viscosity>
To accommodate high-speed printing (50 to 300 m/min) using flexographic printing, the viscosity of the coating agent produced by the above method is preferably in the range of 100 to 1,000 cps at 25°C as measured by a Brookfield viscometer. A more preferred range is 400 to 800 cps. This viscosity range corresponds to a viscosity of approximately 10 to 40 seconds using a Zahn cup #4. The viscosity of the coating agent can be adjusted by appropriately selecting the types and amounts of raw materials used, such as the ratios of the urethane resin, nitrocellulose resin, and organic solvent. The viscosity of the coating agent can also be adjusted by adjusting the particle size and particle size distribution of the extender pigment in the coating agent.

<Base material>
The substrate that can be used in the present invention is preferably a plastic substrate. Examples of the plastic substrate include polyolefin substrates such as polyethylene and polypropylene, polyester substrates such as polyethylene terephthalate and polylactic acid, polycarbonate substrates, acrylic substrates such as polymethyl methacrylate, polyamide substrates such as 6-nylon and 6,6-nylon, cellulose substrates such as cellulose acetate, cellulose propionate, and nitrocellulose, chlorine-based substrates such as polyvinyl chloride and polyvinylidene chloride, fluorine-based resin polystyrene substrates such as polytetrafluoroethylene and polyvinylidene fluoride, and polystyrene substrates such as AS resin and ABS resin. The substrate is preferably in the form of a film or sheet. The substrate can be obtained using one or a mixture of two or more of these thermoplastic resins. The substrate may be a laminate. It may also be subjected to a surface treatment such as corona treatment. Alternatively, a colored substrate in which a colorant is kneaded into the thermoplastic resin may be used. The colorant is not particularly limited, and the above-mentioned organic pigments, inorganic pigments, etc. can be used as appropriate. In one embodiment, a substrate containing a colorant is also preferred.

<Picture layer>
The printed matter may have a design layer between the substrate and the coating layer. The design layer can be obtained by forming a design layer on the substrate using a printing ink by a rotary printing method such as gravure printing or flexographic printing. For example, the printing ink is diluted with an organic solvent to a viscosity and concentration suitable for gravure printing, and then supplied to each printing unit for printing. The printing method is not particularly limited, and suitable examples include screen printing, gravure printing, flexographic printing, offset printing, and inkjet printing. Of these, gravure printing and flexographic printing are preferred.

Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to the following examples. Furthermore, unless otherwise specified, in the examples and comparative examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively.
Examples 15b, 15c, and 15d are reference examples.

(Weight average molecular weight)
The weight average molecular weight was determined as a polystyrene equivalent molecular weight by measuring the molecular weight distribution using a GPC (gel permeation chromatography) device (Shodex GPC System-21 manufactured by Showa Denko K.K.). The measurement conditions are shown below. Column: The following multiple columns were connected in series and used: TSKgel Super AW2500 manufactured by Tosoh Corporation, TSKgel Super AW3000 manufactured by Tosoh Corporation, TSKgel Super AW4000 manufactured by Tosoh Corporation, TSKgelguard column Super AWH manufactured by Tosoh Corporation. Detector: RI (differential refractometer). Measurement conditions: column temperature 40°C, eluent: tetrahydrofuran. Flow rate: 1.0 mL/min.

(glass transition temperature)
The glass transition temperature (Tg) was determined by differential scanning calorimetry (DSC) using a Rigaku Corporation DSC8231 measuring instrument, with a measurement temperature range of −70 to 250°C, a heating rate of 10°C/min, and the midpoint between the endothermic start and end temperatures due to the glass transition in the DSC curve.

(Synthesis Example 1) [Urethane resin PU1]
100 parts of polytetramethylene glycol (hereinafter "PTMG") with a number average molecular weight of 1,000, 100 parts of polycaprolactone (hereinafter "MePCL"), 103.4 parts of isophorone diisocyanate (IPDI), and 75.8 parts of ethyl acetate were reacted under a nitrogen stream at 80°C for 4 hours to obtain a resin solution of isocyanate-terminated urethane prepolymer. Next, the resin solution of isocyanate-terminated urethane prepolymer was gradually added to a mixture of 44.6 parts of isophorone diamine (IPDA) and 755.2 parts of a 50/50 ethyl acetate/IPA (by weight) mixed solvent at 40°C, and the mixture was allowed to react for 1 hour at 80°C to obtain a urethane resin solution PU1 with a solids content of 35% by weight, an amine value of 0.3 mgKOH/g, a hydroxyl value of 0.0 mgKOH/g, and a weight average molecular weight of 30,000.

(Synthesis Examples 2 and 3) [Synthesis of urethane resins PU2 and PU3]
Urethane resins PU2 and PU3 were obtained in the same manner as in Synthesis Example 1, except that the raw materials listed in Table 1 were used.

[Example 1a]
10 parts of urethane resin solution PU1, 40 parts of nitrocellulose resin (weight average molecular weight 52,000, glass transition temperature 150°C, solids content 30 mass% solution), 37.8 parts of organic solvent (n-propyl alcohol/n-propyl acetate = mass ratio 70/30), 2.0 parts of plasticizer B1 (acetyl tri-n-butyl citrate), and 0.2 parts of silver-based inorganic particles F1 (silver-zirconium phosphate particle dispersion average particle size 1.8 μm specific gravity 3) were blended and dispersed for 10 minutes in an Eiger mill, which is a bead mill, after which 10.0 parts of wax E1 (polyethylene-based wax dispersion) was added and mixed by stirring to obtain a coating agent (S1).

Next, the coating agent S1 obtained above was diluted and mixed with a mixed solvent (n-propyl alcohol/n-propyl acetate = mass ratio 70/30) so that the viscosity at 25°C was 13 seconds according to Zahn cup No. 4, and this was flexographically printed on the corona-treated surface of a 60 μm-thick polyethylene substrate at a printing speed of 150 m/min using an anilox (made of stainless steel) with a volume of 12 ^cm3 / ^cm2 and a plate made of photosensitive resin material to obtain a print (layer structure: substrate/coating layer).

[Examples 2a to 19a, Comparative Examples 1a to 4a]
Coating agents (S2 to S19 and SS1 to SS4) were obtained in the same manner as in Example 1, except that the raw materials and blending ratios shown in Table 2 were used. In Table 2, blank spaces indicate no blending. Of these, S1 to 19 are coating agents corresponding to Examples, and SS1 to SS4 are comparative examples, which are compositions that are not coating agents of the present invention. Details of the abbreviations for the materials used in Tables 2 and 4 are shown in Table 6.

Example 1b
10 parts of urethane resin solution PU1, 40 parts of nitrocellulose resin (weight average molecular weight 52,000, glass transition temperature 150°C, solids content 30 mass% solution), 36.0 parts of organic solvent (n-propyl alcohol/n-propyl acetate = mass ratio 70/30), 2.0 parts of plasticizer B1 (acetyl tri-n-butyl citrate), and 2.0 parts of silver-based inorganic particles G1 (silver-zinc calcium phosphate particle dispersion average particle size 4.2 μm) were blended and dispersed for 10 minutes using an Eiger mill, which is a bead mill, after which 10.0 parts of wax E1 (polyethylene wax dispersion) was added and mixed by stirring to obtain coating agent (T1).

Next, the coating agent T1 obtained above was diluted and mixed with a mixed solvent (n-propyl alcohol/n-propyl acetate = mass ratio 70/30) so that the viscosity at 25°C was 13 seconds on a Zahn cup No. 4 test, and this was flexographically printed on the corona-treated surface of a 60 μm-thick polyethylene substrate at a printing speed of 150 m/min using an anilox (made of stainless steel) with a volume of 12 ^cm3 / ^cm2 and a plate made of a photosensitive resin material to obtain a print (layer structure: substrate/coating layer).

[Examples 2b-19b, Comparative Examples 1b-4b] Coating agents (T2-T19 and TT1-TT4) were obtained in the same manner as Example 1b, except that the raw materials and blending ratios listed in Table 4 were used. Note that in Table 4, blank spaces indicate no blending. Of these, T1-T19 are coating agents corresponding to the respective examples, and TT1-TT4 are comparative examples, each of which is a composition that is not a coating agent of the present invention.

[Examples 1c to 21c, Comparative Examples 1c to 4c]
Coating agents (J2 to J21 and JJ1 to JJ4) were obtained in the same manner as in Example 1, except that the raw materials and blending ratios shown in Table 7 were used. In Table 7, blank spaces indicate no blending. Of these, J1 to J21 are coating agents corresponding to Examples, and JJ1 to JJ4 are comparative examples, which are compositions that are not coating agents of the present invention. Details of the abbreviations for the materials used in Table 7 are shown in Table 6.

[Examples 1d to 21d, Comparative Examples 1d to 4d]
Coating agents (K2 to K21 and KK1 to KK4) were obtained in the same manner as in Example 1, except that the raw materials and blending ratios shown in Table 9 were used. In Table 9, blank spaces indicate no blending. Of these, K1 to K21 are coating agents corresponding to Examples, and KK1 to KK4 are comparative examples, which are compositions that are not coating agents of the present invention. Details of the abbreviations for the materials used in Table 9 are shown in Table 6.

<Evaluation of Coating Agents>
The coating agents shown in Tables 2 and 4 were evaluated for antibacterial activity, antiviral activity, blocking resistance, substrate adhesion, abrasion resistance, heat resistance, blocking resistance, and curling properties by the following methods, and the results are shown in Tables 3 and 5.

In addition, the antibacterial properties of the resulting coating layer were also confirmed after adding abrasion resistance.

In addition, the antiviral properties of the resulting coating layer were also confirmed after adding abrasion resistance.

<Antibacterial>
The printed matter was subjected to an antibacterial test against Escherichia coli or Staphylococcus aureus in accordance with Japanese Industrial Standard JIS Z 2801:2000 "Antibacterial processed products - Antibacterial test methods and antibacterial effects" 5.2 Test methods for plastic products, etc. An antibacterial activity value of 2.0 or higher was determined to be effective.

<Antiviral>
In the above printed matter, influenza virus solution and feline calicivirus solution were used instead of bacterial solution, in accordance with the film adhesion method of JIS Z2801:2000 "Antibacterial Finished Products - Antibacterial Test Methods and Antibacterial Effect." The conditions after inoculation of the virus onto the surface of the test specimen were 25°C for 24 hours, and polyethylene film was used as a control. The virus infectivity titer was determined using the plaque measurement method described in Appendix B of JIS L1922 "Antiviral Test Methods for Textile Products," and the antiviral activity value was calculated. An antiviral activity value of 2.0 or higher was evaluated as having antiviral effect.

<Adhesion to substrate>
For the above printed matter, cellophane tape was applied to the printed surface and quickly peeled off. The adhesion of the coating agent to the film was evaluated by comparing the area where the tape was applied with the area where the coating agent peeled off from the film. If the evaluation was "C" or higher, there would be no particular problem in actual use. (Evaluation Criteria)
A. The coating layer does not peel off at all (Excellent)
B. The area of the coating layer peeled from the film was 0% to less than 10% of the tape adhesive area (good).
C. The area of the coating layer that has peeled off from the film is 10% to less than 30% of the tape adhesive area (acceptable)
D. The area where the coating layer has peeled off from the film is 30% or more but less than 50% of the tape adhesive area (unacceptable)
E. The area where the coating layer has peeled off from the film is 50% or more of the tape adhesive area (poor).

<Abrasion resistance>
The abrasion resistance of the above printed matter was evaluated using a Gakushin abrasion fastness tester. The evaluation conditions were a load of 200 g, three times back and forth, and the paper used was fine paper. The abrasion resistance of the coating layer of the printed matter after fastness was evaluated. A rating of "C" or higher means there are no particular problems in actual use.
(Judgment criteria)
A. The coating layer does not peel off at all (Excellent)
B. The coating layer has peeled off from the paper by more than 0% to less than 5% of the solid area (good).
C. The coating layer has peeled off from the paper by 5% to less than 10% of the solid area (acceptable).
D. The coating layer has peeled off from the paper by 10% to less than 30% of the solid area (unacceptable)
E. The coating layer has peeled off from the paper by 30% or more of the solid area (poor).

<Heat resistance>
Aluminum foil was laminated to the printed surface of the above printed material, and heat history was applied to both sides of the laminated printed material using a heat seal tester. After the printed material had cooled, the aluminum foil was peeled off from the printed material. The heat resistance of the coating layer was evaluated by comparing the area where the aluminum foil and printed material were laminated with the area where the coating layer had peeled off from the film. A rating of "C" or higher indicates that there are no particular problems in actual use.
(Judgment criteria)
A. The coating layer adheres perfectly to the aluminum surface and does not peel off at all (Excellent)
B. The area of the coating layer that has peeled off from the film is between 0% and less than 5% of the area of the aluminum foil bonded together (good).
C. The area where the coating layer has peeled off from the film is 5% or more but less than 10% of the area where the aluminum foil is attached (acceptable).
D. The area where the coating layer has peeled off from the film is 10% or more but less than 30% of the area where the aluminum foil is attached (unacceptable)
E. The area where the coating layer has peeled off from the film is 30% or more of the area where the aluminum foil is attached (poor).

<Blocking resistance>
The printed matter was cut into 4 cm x 4 cm pieces, and the polypropylene substrate cut to the same size was placed on top of it. A load of 5 kg/cm was applied, and the material was left to stand for 24 hours in an atmosphere of 40°C and 80% RH. The printed surface and film were then peeled off, and the degree of removal of the coating layer was visually evaluated. A rating of "C" or higher indicates no particular problems in actual use.
(Criteria A: The coating layer does not peel off at all (Excellent)
B. Coating layer peeled off from over 0% to less than 5% (good)
C. Coating layer peeling of 5% to less than 10% (acceptable)
D. Coating layer peeling of 10% to less than 30% (unacceptable)
E. 30% or more of the coating layer has peeled off, or the printed surface and film are completely adhered together and cannot be peeled off (poor).

<Curl suitability>
The above printed matter was cut into pieces measuring 10 cm x 10 cm, and cuts were made from the upper left corner to the right corner and from the upper right corner to the upper left corner, and the printed matter was left to stand for 24 hours. After 24 hours, the curling suitability of the printed matter was evaluated based on the degree of warping of the cut parts. A rating of "C" or higher poses no particular problems in actual use.
(Judgment criteria)
A. The cut area does not bend or curl at all. (Excellent)
B. Warpage of more than 0.0 cm to less than 0.5 cm was observed at the cut. (Good)
C. Warpage of 0.5 cm or more but less than 1.0 cm was confirmed at the cut. (Acceptable)
D. Warpage of 1.0 cm or more but less than 1.5 cm was confirmed at the cut. (Not acceptable)
E. Warpage of 1.5 cm or more at the cut was confirmed. (Poor)

When the coating agent of the present invention was used, excellent results were obtained in all areas, including antibacterial properties, substrate adhesion, abrasion resistance, heat resistance, blocking resistance, and curling properties, as shown in Tables 3 and 5 (Examples 1 to 19). In addition, when a coating agent other than that of the present invention was used, it was found that there were problems with antibacterial properties, substrate adhesion, abrasion resistance, heat resistance, blocking resistance, or curling properties, making it difficult to use.

<Reverse gloss>
The above printed matter was evaluated for reverse gloss using a multi-rub tester (reciprocating rotary abrasion tester). The printed matter was cut into pieces measuring 7 cm x 7 cm and attached to the head, with a K-liner attached to the stage. As the head and stage were repeatedly abraded, the printed matter and the cardboard were rubbed against each other, causing the surface of the printed matter to wear and develop reverse gloss. The reverse gloss that developed was evaluated. Similarly, the reverse gloss when the printed matter was attached to the stage was also evaluated.
If the rating is "C" or higher, there will be no particular problem in actual use. In the following ratings, "%" represents area %.
(Judgment criteria)
A. No negative gloss occurs on the surface of the printed matter. (Excellent)
B. Reverse gloss can be seen only when the printed surface is viewed from different angles (Good).
C. When the printed surface is visually inspected from the front, the occurrence of reverse gloss can be confirmed. The occurrence of reverse gloss is less than 10% of the worn area (acceptable).
D. When the printed surface is visually inspected from the front, the occurrence of reverse gloss is easily confirmed, and the occurrence of reverse gloss is 10% or more but less than 30% of the worn area. (Not acceptable)
E. When the printed surface is visually inspected from the front, the occurrence of reverse gloss is easily confirmed, and the occurrence of reverse gloss is 30% or more of the worn area. (Poor)

<Matte finish>
The gloss value of the printed matter was measured using a Micro Trigloss (gloss meter, manufactured by BYK) and used as an index of matte finish. The matte finish was evaluated based on the gloss value. Generally, the lower the gloss value, the higher the matte finish.
If the rating is "C" or higher, there will be no particular problem in actual use.
(Judgment criteria)
A. Gloss value less than 4 (excellent)
B. Gloss value is 4 or more and less than 7 (good)
C. Gloss value is 11 or more but less than 11 (acceptable)
D. Gloss value is 11 or more and less than 15 (unacceptable)
E. Gloss value is 15 or more (poor)

[Examples 1e to 4e]
The negative gloss and matte finish were evaluated for each of the printed materials using the following coating compositions, and the results were as follows.
Printed matter using coating composition S18 Reverse gloss: C Matte: C
Printed matter using coating composition S19 Reverse gloss: C Matte: C
Printed matter using coating composition T18 Reverse gloss: C Matte: C
Printed matter using coating composition T19 Reverse gloss: C Matte: C

Claims (12)

An antibacterial and antiviral coating agent containing a urethane resin, a nitrocellulose resin, an organic solvent, a plasticizer, and inorganic particles,
the plasticizer includes at least one selected from the group consisting of citrate esters, phthalate esters, phosphate esters, trimellitates, aliphatic dibasic acid esters, and sulfonate amides, and the inorganic particles include silver-based inorganic particles;
The antibacterial and antiviral coating agent , wherein the silver-based inorganic particles are silver-zirconium phosphate particles . An antibacterial and antiviral coating agent containing a urethane resin, a nitrocellulose resin, an organic solvent, a plasticizer, and inorganic particles,
the plasticizer includes at least one selected from the group consisting of citrate esters, phthalate esters, phosphate esters, trimellitates, aliphatic dibasic acid esters, and sulfonate amides, and the inorganic particles include silver-based inorganic particles;
The antibacterial and antiviral coating agent, wherein the silver-based inorganic particles are silver-zinc calcium phosphate particles. 2. The antibacterial and antiviral coating agent according to claim 1 , wherein the silver-zirconium phosphate particles are contained in an amount of 0.05 to 0.9% by mass based on the total mass of the coating agent. 3. The antibacterial and antiviral coating agent according to claim 2 , wherein the coating agent contains 0.5 to 9% by mass of silver-zinc calcium phosphate particles based on the total mass of the coating agent. The antibacterial and antiviral coating agent according to any one of claims 1 to 4 , wherein the inorganic particles have an average particle size of 0.5 to 10 µm. The antibacterial and antiviral coating agent according to any one of claims 1 to 5 , wherein the mass ratio of the urethane resin to the nitrocellulose resin is 2/98 to 50/50. The antibacterial and antiviral coating agent according to any one of claims 1 to 5 , further comprising an extender pigment and/or resin fine particles. The antibacterial and antiviral coating agent according to claim 7 , wherein the mass ratio of the urethane resin to the nitrocellulose resin is 98/2 to 50/50. The antibacterial and antiviral coating agent according to any one of claims 1 to 8 , which is used for flexographic printing. An antibacterial and antiviral printed matter having an antibacterial and antiviral coating layer formed from the antibacterial and antiviral coating agent according to any one of claims 1 to 9 on a substrate. A method for producing an antibacterial and antiviral printed matter, the method comprising a step of flexographically printing an antibacterial and antiviral coating agent onto a plastic substrate, wherein the antibacterial and antiviral coating agent contains a urethane resin, a nitrocellulose resin, an organic solvent, a plasticizer, and inorganic particles, the plasticizer contains at least one plasticizer selected from a citrate ester-based, a phthalate ester-based, a phosphate ester-based, a trimellitate ester-based, an aliphatic dibasic acid ester-based, and a sulfonate amide-based plasticizer , and the inorganic particles contain silver-based inorganic particles, which are silver-zirconium phosphate particles . A method for producing an antibacterial and antiviral printed matter, comprising a step of flexographically printing an antibacterial and antiviral coating agent onto a plastic substrate, wherein the antibacterial and antiviral coating agent contains a urethane resin, a nitrocellulose resin, an organic solvent, a plasticizer, and inorganic particles, the plasticizer contains at least one selected from a citrate ester-based, a phthalate ester-based, a phosphate ester-based, a trimellitic acid ester-based, an aliphatic dibasic acid ester-based, and a sulfonate amide-based plasticizer, and the inorganic particles contain silver-based inorganic particles, which are silver-zinc calcium phosphate particles.