JP2023004163A - antibacterial film - Google Patents

Abstract

To provide an antibacterial film that has a coating film having both of a gas barrier property and an antibacterial property, and has an excellent appearance where no foreign object occurs.SOLUTION: An antibacterial film has a coating film containing a gas barrier resin (A) and an organic antibacterial agent (B) on at least one surface of a substrate layer, wherein a coating amount is 0.01 g/m2 or more and 30 g/m2 or less.

Description

TECHNICAL FIELD The present invention relates to an antibacterial film having a coating that has both gas barrier properties and antibacterial properties. More specifically, it has a film that has both gas barrier properties and antibacterial properties, and can be suitably used for packaging and storage containers for food, pharmaceuticals, medical equipment, sanitary materials, etc., building materials, miscellaneous goods, home appliances, etc. It relates to antibacterial films.

In recent years, it has become a problem that food is discarded without being eaten, and as a means of extending the expiration date/best before date of food, films with gas barrier properties and antibacterial films have been developed. In addition, along with the rise in environmental awareness, the development of thinner products, reduction of raw materials used, improvement of recyclability, etc. is being actively carried out.

For example, Patent Document 1 discloses a polyethylene film having a gas barrier polyvinyl alcohol film as an outer layer and a silver ion-based antibacterial agent as an inner layer.
Further, Patent Document 2 discloses a resin film in which antibacterial resin films are laminated on both sides of a barrier film, and as the antibacterial resin film, a resin film containing antibacterial particles obtained by enclosing an organic antibacterial agent with cyclodextrin is disclosed. there is

WO2008/139593 JP-A-8-282741

The polyethylene film disclosed in Patent Document 1 has a silver ion-based antibacterial agent, but the silver ion-based antibacterial agent is an inorganic antibacterial agent and does not melt or dissolve in the polyethylene film. In addition, when the amount of the antibacterial agent used is large, there is a problem that foreign matter tends to be generated and the appearance of the film is spoiled.
In addition, in the barrier film disclosed in Patent Document 2, if an attempt is made to increase the amount of the antibacterial particles used in order to exhibit sufficient antibacterial properties, the antibacterial particles do not dissolve in the resin film. There is a problem that the appearance of the film is damaged due to the generation of aggregates and foreign matter.
Furthermore, when used for a thin resin film, there is a problem in film formation such as breakage of the film originating from the inorganic particles.

An object of the present invention is to provide an antibacterial film that has a coating that has both gas barrier properties and antibacterial properties and that has a good appearance without the generation of foreign matter.

As a result of intensive studies, the present inventors have found that by having a coating containing a gas barrier resin and a specific antibacterial agent, an antibacterial film having gas barrier properties, antibacterial properties, and a good appearance without the generation of foreign matter etc. The present inventors have found that it can be produced, and have completed the present invention.

That is, the gist of the present invention is as follows.
[1] A coating containing a gas barrier resin (A) and an organic antibacterial agent (B) is provided on at least one surface of the substrate layer, and the coating amount is 0.01 g/m ² or more and 30 g/m ² or less. There is an antibacterial film.
[2] The antibacterial film according to [1] above, wherein the film is a coating.
[3] The antibacterial film according to [1] or [2] above, wherein the organic antibacterial agent (B) is at least one selected from organic acid salts.
[4] The organic antibacterial agent (B) is at least one selected from the group consisting of sorbates, dehydroacetates, propionates, acetates, and benzoates [1] to [3] ] The antibacterial film according to any one of the above.
[5] The antibacterial film according to any one of [1] to [4] above, wherein the gas barrier resin (A) is a polyvinyl alcohol resin.
[6] Any one of the above [1] to [5], wherein the gas barrier resin (A) and the organic antibacterial agent (B) are present in a mass ratio of 99:1 to 70:30. An antimicrobial film as described.
[7] The antibacterial performance of the film has an antibacterial activity value of 2.0 or more in an antibacterial test using baker's yeast in accordance with JIS Z2801 (2012), above [1] to [ 6], the antibacterial film according to any one of the items.
[8] The antibacterial film according to any one of [1] to [7] above, which is for food packaging.
[9] A coating composition containing a gas barrier resin (A) and an organic antibacterial agent (B), wherein the mixing ratio of the gas barrier resin and the organic antibacterial agent is 99:1 to 70: 30 coating composition.
[10] A method of forming a film, comprising applying the coating composition according to [9] above to a film.

According to the present invention, an antibacterial film having gas barrier properties and antibacterial properties can be provided. In particular, it can be suitably used for applications requiring gas barrier properties, antibacterial properties, and external appearance.

Hereinafter, the present invention will be described as an example of embodiments of the present invention. However, the scope of the present invention is not limited to the embodiments described below.

[Antibacterial film]
The antibacterial film of the present invention has a coating containing a gas barrier resin (A) and an organic antibacterial agent (B) on at least one surface of a substrate layer, and the coating amount is 0.01 g/m ² or more and 30 g. /m ² or less.

<Gas barrier resin (A)>
As the gas-barrier resin, a resin having low permeability to oxygen, nitrogen, carbon dioxide, water vapor, or the like can be used, and can be selected according to the application and contents. Among them, it is preferable to use a resin with low oxygen permeability, and it is preferable that the oxygen permeability obtained by a method conforming to JIS K7126-2 (2006) is 50 cc/m ² ·24 hr·atm or less.
Examples of gas barrier resins include polyamide resins (PA), polyvinyl alcohol resins (PVOH) such as ethylene-vinyl alcohol copolymer resins (EVOH), polyvinylidene chloride (PVDC), polyacrylonitrile (PAN), pullulan, starch, Water-soluble polysaccharides such as dextrin, sodium alginate, carboxymethylcellulose, or derivatives thereof, gelatin, and the like can be mentioned. One of these may be used alone, or a plurality thereof may be used in combination. Polyvinyl alcohol resin (PVOH) is preferable from the viewpoint of gas barrier properties and ease of solution formation with the organic antibacterial agent (B), and among polyvinyl alcohol resins (PVOH), from the viewpoint of gas barrier properties and water resistance. Ethylene-vinyl alcohol copolymer resin (EVOH) is preferred.

<Polyvinyl alcohol resin (PVOH)>
Polyvinyl alcohol-based resins can usually be produced by polymerizing vinyl ester-based monomers and saponifying them. It can also be produced by saponifying or post-modifying a copolymer of a vinyl ester monomer and another unsaturated monomer. As a method for polymerizing the vinyl ester monomer, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like can be applied. As the polymerization catalyst, an azo catalyst, a peroxide catalyst, a redox catalyst, or the like can be appropriately selected according to the polymerization method. For the saponification reaction, alcoholysis, hydrolysis, or the like using an alkali catalyst or an acid catalyst can be applied.
Preferred examples of copolymers of vinyl ester monomers and other unsaturated monomers include ethylene-vinyl alcohol copolymer resins (EVOH). As the polyvinyl alcohol-based resin, a polyvinyl alcohol resin (PVA) composed only of a vinyl ester-based monomer that is not copolymerized with a copolymer component can also be used.

Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate. , aliphatic vinyl esters such as vinyl trifluoroacetate, and aromatic vinyl esters such as vinyl benzoate. Among them, aliphatic vinyl esters having 3 to 20 carbon atoms are preferable, more preferably 4 to 10 carbon atoms, particularly preferably 4 to 7 carbon atoms, and vinyl acetate is further preferable. These are usually used alone, but if necessary, multiple types may be used at the same time.

Examples of the above-mentioned other unsaturated monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene and α-octadecene, acrylic acid, methacrylic acid, crotonic acid, maleic acid and maleic anhydride. , unsaturated acids such as itaconic acid, salts thereof, mono- or dialkyl esters thereof, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide and methacrylamide, ethylenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, etc. olefin sulfonic acid or salts thereof, alkyl vinyl ethers, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, polyoxyethylene (meth)allyl ether, Polyoxyalkylene (meth)allyl ether such as polyoxypropylene (meth)allyl ether, polyoxyalkylene (meth)acrylate such as polyoxyethylene (meth)acrylate, polyoxypropylene (meth)acrylate, polyoxyethylene (meth)acrylate Acrylamide, polyoxyalkylene (meth)acrylamide such as polyoxypropylene (meth)acrylamide, polyoxyethylene (1-(meth)acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, poly Oxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine and the like. These can be used alone or in combination of two or more. The above-mentioned "(meth)allyl" means allyl or methallyl, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acryl" means acrylic or methacryl, respectively.

The average degree of saponification of the polyvinyl alcohol resin is usually 70 to 100 mol%, preferably 80 to 100 mol%, particularly preferably 85 to 100 mol%, more preferably 90 to 99.99 mol%. When the average degree of saponification is 70 mol % or more, water resistance and gas barrier properties are improved. In addition, said average degree of saponification is measured based on JISK6726 (1994).
The average degree of polymerization of the polyvinyl alcohol resin is usually 100 to 4,000, preferably 200 to 3,000, particularly preferably 300 to 2,500. When the average degree of polymerization is at least the above lower limit value, mechanical properties such as coating strength are good, and when it is at most the above upper limit value, it is easy to be dissolved, which is preferable in terms of handleability. In addition, the said average degree of polymerization is measured based on JISK6726 (1994).
As the vinyl alcohol resin, two or more different modified species, modified amount, average degree of saponification, average degree of polymerization, etc. may be used in combination.

<Ethylene-vinyl alcohol copolymer resin (EVOH)>
As the gas barrier resin (A), as described above, polyvinyl alcohol resin (PVOH) is preferable, and ethylene-vinyl alcohol copolymer resin (EVOH) is particularly preferable from the viewpoint of water resistance.
Ethylene-vinyl alcohol copolymer resin is usually a resin obtained by saponifying a copolymer of ethylene and a vinyl ester monomer (ethylene-vinyl ester copolymer), and is a water-insoluble thermoplastic. Resin. Polymerization can be carried out using any known polymerization method such as solution polymerization, suspension polymerization, and emulsion polymerization, but solution polymerization using a lower alcohol such as methanol as a solvent is generally used. Saponification of the resulting ethylene-vinyl ester copolymer can also be carried out by a known method. The ethylene-vinyl alcohol copolymer resin thus produced has ethylene structural units and vinyl alcohol structural units as main structural units, and contains a small amount of residual vinyl ester structural units that have not been saponified.

As the vinyl ester-based monomer, vinyl acetate is typically used because it is readily available on the market and is efficient in removing impurities during production. Other usable vinyl ester monomers are as described above.

The ethylene content in the ethylene-vinyl alcohol copolymer resin is preferably 15 to 50 mol %, more preferably 20 to 45 mol %, as measured according to ISO14663. When the ethylene content is at least the above lower limit, good gas barrier properties and melt moldability are obtained. On the other hand, when the content is equal to or less than the above upper limit, the melt viscosity on the low shear side does not decrease, and the solubility in solvents is good.

The degree of saponification of the vinyl ester component in the ethylene-vinyl alcohol copolymer resin is a value measured in accordance with JIS K6726 (1994) using a solution uniformly dissolved in a water/methanol solvent, and is 90 to 100 mol%. preferably 95 to 100 mol %. Gas barrier properties, thermal stability, moisture resistance, and the like are good when it is at least the above lower limit.

The melt flow rate (MFR) (210° C., load 2.16 kgf) of the ethylene-vinyl alcohol copolymer resin is preferably 0.5 to 100 g/10 min, more preferably 1 to 50 g/10 min, especially It is preferably 2 to 35 g/10 minutes. If it is said range, film-forming property and coating property will be favorable.

In addition to ethylene structural units and vinyl alcohol structural units (including unsaponified vinyl ester structural units), ethylene-vinyl alcohol copolymer resins may further contain structural units derived from the following comonomers. good. Examples of the above comonomer include α-olefins such as propylene, isobutene, α-octene, α-dodecene, α-octadecene; hydroxy group-containing α-olefins such as 2-diols, esters thereof, hydroxy group-containing α-olefin derivatives such as acylated products; unsaturated carboxylic acids or salts thereof, partial alkyl esters thereof, complete alkyl esters thereof, nitriles thereof, its amide or its anhydride; unsaturated sulfonic acid or its salt; vinylsilane compound; vinyl chloride;

The ethylene-vinyl alcohol copolymer resin contains compounding agents that can generally be compounded in EVOH, such as heat stabilizers, antioxidants, antistatic agents, colorants, and ultraviolet absorbers, as long as they do not impair the effects of the present invention. , Lubricants, plasticizers, light stabilizers, surfactants, desiccants, anti-blocking agents, flame retardants, cross-linking agents, curing agents, foaming agents, crystal nucleating agents, anti-fogging agents, biodegradable additives, oxygen absorbers etc. may be contained.

In addition, the ethylene-vinyl alcohol copolymer resin may be a mixture with other different ethylene-vinyl alcohol copolymer resins, and such other EVOH may have different ethylene contents or different degrees of saponification. , different melt flow rate (MFR) (210 ° C., load 2.16 kgf), different copolymer components, different amounts of modification (for example, different contents of 1,2-diol structural units), etc. can be mentioned.

In addition to the ethylene-vinyl alcohol copolymer resin, the ethylene-vinyl alcohol copolymer resin may optionally contain other resins as long as the effects of the present invention are not impaired. may be a resin that does not have gas barrier properties.
Other resins include polyamide resins such as nylon 11, nylon 12, nylon 6, nylon 66, and nylon 6/66, polyvinyl alcohol resins other than EVOH, polyvinylidene chloride (PVDC), and polyacrylonitrile (PAN). , water-soluble polysaccharides (pullulan, starch, dextrin, sodium alginate, carboxymethylcellulose, derivatives thereof, etc.), gelatin, other thermoplastic resins, and the like may be used in combination.
The content of resins that can be blended in addition to the ethylene-vinyl alcohol copolymer resin is usually 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, relative to EVOH.

<Organic antibacterial agent (B)>
The antibacterial agent used in the present invention is not particularly limited as long as it is an organic antibacterial agent. For example, benzoic acid, dehydroacetic acid, sorbic acid, propionic acid, acetic acid, formic acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, etc. monocarboxylic acids, salts of the above monocarboxylic acids such as sodium dehydroacetate, potassium sorbate, sodium propionate, sodium benzoate; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaine acids, dicarboxylic acids such as sebacic acid, salts thereof; lactic acid, gluconic acid, glycolic acid, glyceric acid, malic acid, citric acid, tartaric acid, hydroxyacetic acid, hydroxybutyric acid, tartronic acid, salicylic acid, (m-, p-) Hydroxy acids such as hydroxybenzoic acid, 12-hydroxydodecanoic acid, 12-hydroxyisobutyric acid, (o-, m-, p-)hydroxyphenylacetic acid, 4-hydroxyphthalic acid, 12-hydroxystearic acid, salts thereof, etc. organic acid-based antibacterial agents; amino acid-based antibacterial agents such as glycine; Quaternary ammonium salt antibacterial agents such as didecyldimethylammonium and domiphen bromide; Surfactant antibacterial agents such as lauryldimethylbenzylammonium chloride; organometallic antibacterial agents such as zinc naphthenate; phthalimide antibacterial agents such as N-fluorodichloromethylthiophthalimide; thiocarbamate antibacterial agents such as polycarbamate; disulfide antibacterial agents such as bisdimethylthiocarbamoyl disulfide; carbanilide antibacterial agents such as 3,4,4-trichlorocarbanilide; 2-benzimidazole methylcarbamate, thiabendazole, 1-(Butylcarbamoyl)-2-benzimidazole Imidazole/thiazole antibacterial agents such as methyl carbamate; 2-methyl-4-isothiazolinone-3-one, 1,2-benzisothia Zorin-3-one, 2-methyl-5-chloro-4-isothiazolone complex, 2-n-octyl-4-isothiazolin-3-one, dichlorooctylisothiazolinone, isothiazolinone-based antibacterial agents such as endoisothiazolinone; hexahydro -triazine antimicrobial agents such as 1,3,5-triethyl-S-triazine; pyridine-quinoline antimicrobial agents such as nalidixic acid, pyrithione copper, pyrithione zinc, 2-mercaptopyridine-N-oxide zinc; Halogen-based antibacterial agents such as trisulfone and polyvinylpyrrolidone iodide; peroxide-based antibacterial agents such as peracetic acid; Antibacterial agents; ether antibacterial agents such as 2,4,4-trichloro-2-hydroxyldiphenyl ether; ester antibacterial agents such as glyceryl laurate and ethyl hydroxybenzoate; aldehyde antibacterial agents such as formaldehyde; cresol, o-phenyl phenol, 2-isopropyl-5-methylphenol, ethanol, ethyl-2,4-dihydroxy-6-methylbenzoate, methyl-2,4-dihydroxy-3,6-dimethylbenzoate, isopropyl-2,4-dihydroxy-6 -methylbenzoate, 3-methoxy-5-methylphenyl-2,4-dihydroxy-6-methylbenzoate, ethyl-2,4-dihydroxy-3,6-dimethylbenzoate, ethyl-3-formyl-2,4-dihydroxy -6-methylbenzoate, isopropyl-3-formyl-2,4-dihydroxy-6-methylbenzoate, 3-hydroxy-5-methylphenyl-2,4-dihydroxy-6-methylbenzoate, 3-methyl-4 isopropylphenol , 3-hydroxy-5-methylphenyl-2-dihydroxy-4-methoxy-6-methylbenzoate, 3-methoxy-5-methylphenyl-2-hydroxy-4-methoxy-6-methylbenzoate, 3-chloro-2 , 6-dihydroxy-4-methylbenzoate and other phenol-alcohol antibacterial agents. These organic antibacterial agents may contain only one type, or may contain two or more types.

The organic acid antibacterial agent is easy to handle due to its thermal stability and solubility in a solution, and particularly among the organic acid antibacterial agents, organic acid salts having a salt form are preferable.
Furthermore, sorbates, dehydroacetates, propionates, acetates, and benzoates are preferred from the viewpoints of safety to organisms, availability, cost, and the like. These sorbates, dehydroacetates, propionates, acetates, and benzoates are listed in the Food Additives Codex established by the Ministry of Health, Labor and Welfare, and are more preferable in terms of safety.

<Base material layer>
The base layer in the antibacterial film of the present invention is not particularly limited as long as it is obtained from various synthetic resin materials that can be formed into a film. It is preferable to use a thermoplastic resin as the synthetic resin material because of ease of handling such as moldability into a film and secondary processability as an antibacterial film, and the base layer contains a thermoplastic resin. Layers are preferred.
Various thermoplastic resins can be used as the thermoplastic resin. For example, polyethylene (PE), polyolefin resin (PO) such as polypropylene (PP), polyamide resin (PA), polystyrene resin (PS), polyethylene Examples include polyester resins such as terephthalate (PET) and polyethylene naphthalate (PEN), polyvinyl chloride resins (PVC), ethylene-vinyl alcohol copolymer resins (EVOH), and the like. These resins can be used singly or in combination of two or more.
Specifically, films that are widely used as wrap films, molded films, single-layer films, multilayer films, and films for lid materials can be used.
Among the above resins, polyolefin resins such as PE and PP are preferable from the viewpoint of heat sealability.

The thickness of the substrate layer is not particularly limited, but is preferably in the range of 5 to 600 μm, more preferably in the range of 10 to 500 μm, even more preferably in the range of 12 to 400 μm. When the thickness of the substrate layer is at least the above lower limit, it is easy to form a film, and when it is at most the above upper limit, it is advantageous in terms of cost.
Moreover, the base layer in the antibacterial film of the present invention may contain a gas barrier layer. On the other hand, since the antibacterial film of the present invention is provided with a gas barrier property by the coating, it is effective to use a substrate that originally has a low gas barrier property.

(Laminated film)
Further, the substrate layer in the antibacterial film of the present invention may be a single layer, or may be a laminated film having a plurality of layers.
In the case of a single layer, it is preferable that the substrate layer comprising a single layer is a layer containing a thermoplastic resin.
When using a laminated film, each layer may be a layer containing a thermoplastic resin, but from the viewpoint of improving the heat-sealing property, the outermost layer constituting the surface on which the film is formed is a layer containing a thermoplastic resin. is preferably More specifically, it is preferable to have a polyolefin layer containing a polyolefin resin such as PE or PP as the outermost layer constituting the surface on which the film is formed.

More specifically, the laminate film has a layer structure such as PP layer/PA layer/EVOH layer/PA layer/PE layer. The PP layer and PE layer mean layers containing polypropylene and polyethylene, respectively. Moreover, the EVOH layer and the PA layer have a function as a gas barrier layer as described above. By having a gas barrier layer in the substrate layer, the antibacterial film of the present invention can be suitably used for food packaging. As such a laminate film, a commercially available one can be used, and examples thereof include "Diamilon" (trade name) manufactured by Mitsubishi Chemical Corporation.

<Coating>
The antibacterial film of the present invention must have a coating containing the gas barrier resin (A) and the organic antibacterial agent (B) on at least one surface of the substrate layer. The antibacterial film of the present invention has a coating amount of 0.01 g/m ² or more and 30 g/m ² or less. If the coating amount is less than 0.01 g/m ² , sufficient antibacterial properties and gas barrier properties cannot be obtained. On the other hand, if the coating amount exceeds 30 g/m ² , it is disadvantageous in terms of cost. From the above points, the coating amount is preferably 0.02 g/m ² or more and 20 g/m ² or less, more preferably 0.03 g/m ² or more and 15 g/m ² or less.
The coating may be provided on one surface of the substrate layer, or may be provided on both the front surface and the back surface.

The thickness of the coating is preferably in the range of 0.01 to 40 μm, more preferably in the range of 0.1 to 30 μm, even more preferably in the range of 1 to 15 μm. When it is at least the above lower limit, sufficient antibacterial properties and sufficient gas barrier properties can be obtained, and from the viewpoint of cost, it is preferably at most the above upper limit.

In addition, the gas barrier resin (A) and the organic antibacterial agent (B) are present in the film preferably in a mass ratio of 99:1 to 70:30, more preferably 98.5:1.5 to 72.5. :28, more preferably 98:2 to 75:25, and particularly preferably 97:3 to 80:20.
By containing the components (A) and (B) in the above ratio, good gas barrier properties and antibacterial performance can be obtained. Within the range of the above ratio, if the content of the organic antibacterial agent is relatively large, the antibacterial properties are improved, and if it is relatively small, the visibility is further improved.

<Gas barrier property>
^{The antibacterial} film of the present invention has excellent gas barrier properties. ·atm is more preferable, 0.06 to 15 cc/m ² ·24 hr·atm is more preferable, and 0.08 to 12 cc/m ² ·24 hr·atm is particularly preferable. Within the above range, a film having both good gas barrier properties and antibacterial properties can be obtained.

<Antibacterial performance>
In the antibacterial film of the present invention, the antibacterial performance of the film is 24 hours after the antibacterial test is performed by changing the bacteria used in the test to baker's yeast in the antibacterial test described in JIS Z2801 (2012). The antibacterial activity value obtained from the number of baker's yeast bacteria is preferably 2.0 or more. When the antibacterial activity value of baker's yeast is 2.0 or more, a film with high antibacterial performance can be obtained.

<Total light transmittance>
The antibacterial film of the present invention preferably has a total light transmittance of 80% or more, more preferably 85% or more, even more preferably 86% or more. When the total light transmittance is 80% or more, the visibility of the contents is excellent when used as a packaging film or the like. For the same reason, the haze value is preferably 40% or less, more preferably 35% or less, even more preferably 30% or less.
The total light transmittance and haze were measured using a haze meter conforming to JIS K7361 (1999) at n = 5 measurement points, and the arithmetic mean was obtained.

[Coating method]
As a method for forming a coating in the antibacterial film of the present invention, a method of applying the following coating composition to the substrate layer (coating) is preferable from the viewpoints of control of the thickness of the coating, ease of handling, and the like. The coating method is not particularly limited, and known means such as dip coating, spin coating, gravure coating, roll coating, curtain coating, die coating, spray coating, electrostatic spraying, silk screen coating, flexographic printing, etc. It can be coated on the substrate layer.

[Coating composition]
The coating composition of the present invention is a composition containing a gas barrier resin (A) and an organic antibacterial agent (B). The solid content concentration of the coating composition is preferably 0.1 to 30% by mass. When it is 0.1% by mass or more, poor coating during coating can be suppressed, and when it is 30% by mass or less, the viscosity of the solution does not become too high and it is easy to apply. From the above viewpoints, the solid content concentration is more preferably 0.5 to 25% by mass, and even more preferably 1 to 20% by mass.
The coating composition is a composition used for forming a film on the substrate layer, and the organic antibacterial agent suitable for use in combination with the gas barrier resin is the organic antibacterial agent described above, more preferably It is an organic acid antibacterial agent.

The mixing ratio of the gas barrier resin (A) and the organic antibacterial agent (B) in the coating composition of the present invention is preferably 99:1 to 70:30, preferably 98.5:1. 0.5 to 72:28, more preferably 98:2 to 75:25, and particularly preferably 97:3 to 80:20.
By satisfying the above range, the antibacterial properties and gas barrier properties of the obtained film are improved. Within the range of the above ratio, the antibacterial properties can be improved by increasing the content of the organic antibacterial agent, and the visibility can be improved by reducing the content of the organic antibacterial agent.

Since the coating composition of the present invention is for forming a coating film on a substrate layer, a mixed solvent of water and alcohols is used as a solvent in consideration of the handleability and wettability to the substrate. However, it is also possible to mix other organic solvents.
Examples of alcohols include alcohols such as methanol, ethanol, isopropanol, ethylene glycol and glycerin.
Examples of organic solvents include dimethylformamide, dimethylsulfoxide, dimethylacetamide, N-methyl-2-pyrrolidone and the like. These can be used alone or in combination with a plurality of organic solvents. By appropriately selecting and including these organic solvents in the coating composition as necessary, the stability and coatability of the composition can be improved.
The organic solvent content in the coating composition is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less. Although the lower limit is not particularly limited, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, from the viewpoint of the stability and coatability of the composition.
In addition, an anchor coating agent and an activator can be appropriately added in order to enhance the adhesion to the base material layer.
Furthermore, in order to improve coatability, an antifoaming agent, a leveling agent, a thickening agent, etc. can be appropriately selected and used.

The substrate layer used in the present invention can be subjected to a surface treatment in order to improve wettability and adhesion with the coating composition and improve coatability. For example, corona treatment, plasma treatment, piranha treatment, UV treatment, ozone treatment, acid treatment, alkali treatment, etching treatment, static elimination treatment, and flame roasting treatment can be used as appropriate.

<Application>
The antibacterial film of the present invention can be used for various purposes, such as food packaging, packaging of pharmaceuticals such as tablets, packaging of medical instruments such as syringes and hypodermic needles, and packaging of sanitary materials such as gauze and masks. It is preferably used. Among them, it is preferable to use it for food packaging.

[Package]
The package of the present invention is a package comprising the antibacterial film of the present invention. As described above, the antibacterial film of the present invention is excellent in antibacterial properties and gas barrier properties, so that it has high antibacterial properties and can be used to package contents such as food without contact with the outside air.
Therefore, the package of the present invention has excellent functions in storing and distributing various items. For example, when the package of the present invention is used for food packaging, the expiration date can be extended. can reduce food loss.

In this specification, when "X to Y" (X and Y are arbitrary numbers) are described, unless otherwise specified, "X or more and Y or less" and "preferably larger than X" or " It also includes the meaning of "preferably smaller than Y".
In addition, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably greater than X" unless otherwise specified, and is described as "Y or less" (Y is an arbitrary number). If not otherwise specified, it also includes the meaning of "preferably smaller than Y".

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
[Evaluation method]
Each film was evaluated by the following methods.

(1) Coating amount Regarding the coating amount, after coating the base layer with the solution prepared in each example and comparative example, it was dried at 80°C for 5 minutes to obtain a measurement sample. The mass of a 10 cm square sample cut from the measurement sample was measured. The coating amount (mass) was calculated by dividing the value obtained by subtracting the average mass of the base material layer before coating from the measured mass by the area.

(2) Coating Thickness The coating thickness was measured using a stand-type constant-pressure thickness gauge in accordance with JIS K7130 (1999). The total thickness of the coating and the thickness of the base film layer was measured, and the thickness of the coating was obtained by subtracting the thickness of the base film layer on which no coating was formed.

(3) Gas barrier properties Gas barrier properties are measured by OX-TRAN in accordance with JIS K 7126-2 (2006), using a film sample with a thickness of 40 μm under an environment of temperature: 23° C. and humidity: 0%, and oxygen permeability is measured. and evaluated.

(4) Transparency (total light transmittance, haze value)
Total light transmittance and haze value were measured using a haze meter "NDH-5000" manufactured by Nippon Denshoku Industries Co., Ltd. according to the light transmittance measurement method described in JIS K7136 (2000) and JIS K7361-1 (1997). .

(5) Film Appearance Five test pieces of 200 mm in the vertical direction and 150 mm in the horizontal direction were cut out from the films obtained in each example and comparative example, and the number of defects such as foreign matter and mold scum was counted. The number was evaluated according to the following criteria.
〇: Less than 5 defects △: 5 or more defects and less than 9 ×: 10 or more defects

(6) Water Resistance A test piece measuring 50 mm in the vertical direction and 50 mm in the horizontal direction was cut out from the film obtained in each of the examples and comparative examples, and used as a measurement sample. 400 μL of water was dripped onto the film-formed surface (coated surface) of the sample, and then the substrate film was overlaid on the water and dried in a dryer at 80° C. for 30 minutes. After that, the peeling behavior when the laminated base film was pulled by hand was used to evaluate the water resistance according to the following criteria.
〇: Can be peeled off with light force △: Cannot be peeled off without applying force ×: Cannot be peeled off with force

(7) Antibacterial performance test Antibacterial performance was performed in accordance with the antibacterial test described in JIS Z2801 (2012), except that the bacteria used in the test were changed to baker's yeast.
Baker's yeast (dry yeast) was prepared as a test bacterium, and an SDA (Sabouraud dextrose agar) medium was prepared as a test medium. After adding 0.1 g of baker's yeast to 9 ml of PSB (phosphate buffered saline) and stirring well, the bacterial solution was further diluted to 10 to the power of 10 to a concentration of about 3.5×10 ² CFU/mL. was prepared to
The film obtained in each example and comparative example was cut into a size of 5 cm×5 cm and used as an evaluation film. After dropping 0.2 mL of the bacterial solution prepared above on the antibacterial processed surface of each film for evaluation, a cover film of 4 cm × 4 cm was covered, the bacterial solution was adhered to the film for evaluation, and placed in a sterilized petri dish. . After that, after culturing for 24 hours at 35 ± 1 ° C. and 90% relative humidity in a constant temperature and humidity chamber, spread the bacterial solution on the evaluation film on the SDA medium, spread it evenly over the entire medium with a platinum loop, After culturing for 24 hours in a constant temperature and humidity chamber at 35±1° C. and a relative humidity of 90%, the number of viable cells after culturing was measured. The antibacterial activity value was calculated by the following formula from the obtained viable count and the viable count after culturing the film containing no antibacterial agent.
Antibacterial activity value = log (number of viable bacteria after culture of film containing no antibacterial agent) - log (number of viable bacteria after culture of film containing antibacterial agent)
From the obtained antibacterial activity values, antibacterial activity values of 2 or more were evaluated as having antibacterial properties, and others were evaluated as having no antibacterial properties.

The raw materials used in each example and comparative example are as follows.
<Gas barrier resin>
(1) Gas barrier resin A1: ethylene-vinyl alcohol copolymer resin (ethylene unit content 29 mol%, degree of saponification 99.6 mol%, MFR 3.4 g/10 min (210°C, load 2.16 kgf))
(2) Gas barrier resin A2: Polyvinyl alcohol resin (manufactured by Kuraray Co., Ltd., PVA124, degree of saponification: 98.0 to 99.0 mol%, average degree of polymerization: 2400)
<Base film resin>
(3) Linear low-density polyethylene (“Novatec LL UF240” manufactured by Nippon Polyethylene Co., Ltd., density 0.924 g/cm ³ , MFR 0.9 g/10 minutes, melting point 123° C.)
<Antibacterial agent>
(4) Sodium dehydroacetate (manufactured by Osaka Kasei Co., Ltd., "Marcaside D")

<Preparation of base film>
Using a coaxial twin-screw extruder, the base film resin is melt extruded from a T-die connected to the tip of the coaxial twin-screw extruder at a set temperature of 210°C, taken up by a casting roll set at 90°C, and cooled and solidified. to obtain a base film having a thickness of 30 μm.

<Example 1>
16% by mass of gas barrier resin A1 was added to 84% by mass of a mixed solvent containing 50% by mass of water and 50% by mass of isopropyl alcohol, and stirred at 60 to 70°C for about 3 hours to prepare a transparent solution. The antibacterial agent was added so that the ratio of the gas barrier resin A1 and the antibacterial agent in the prepared liquid was 96:4 (mass ratio), and the mixture was stirred at 60 to 70°C for 30 minutes to obtain a transparent coating liquid. The obtained coating liquid was applied onto a substrate film so that the film thickness after drying was 6 μm to obtain a film coated with an antibacterial agent. Table 1 shows the evaluation results of the obtained film.

<Example 2>
The same operation as in Example 1 was performed except that the amount of the antibacterial agent was changed so that the mass ratio of the gas barrier resin A1 and the antibacterial agent was 92:8. film. Table 1 shows the evaluation results of the obtained film.

<Example 3>
The same operation as in Example 1 was performed except that the amount of the antibacterial agent was changed so that the mass ratio of the gas barrier resin A1 and the antibacterial agent was 84:16. film. Table 1 shows the evaluation results of the obtained film.

<Example 4>
The same operation as in Example 1 was performed except that the amount of the antibacterial agent added was changed so that the mass ratio of the gas barrier resin A1 and the antibacterial agent was 76:24. A film of 7 μm was obtained. Table 1 shows the evaluation results of the obtained film.

<Example 5>
15% by mass of gas barrier resin A2 was added to 85% by mass of water, and the mixture was stirred at 90 to 95°C for about 1 hour to prepare a transparent solution. An antibacterial agent was added to the prepared liquid so that the ratio of gas barrier resin A2 to the antibacterial agent was 92:8 (mass ratio), and the mixture was stirred at 60 to 70°C for 30 minutes to obtain a transparent coating liquid. The obtained coating liquid was applied onto a substrate film so that the film thickness after drying was 8 μm to obtain a film coated with an antibacterial agent. Table 1 shows the evaluation results of the obtained film.

<Comparative Example 1>
The same operation as in Example 1 was carried out, except that no antibacterial agent was added, to obtain a film coated with only the gas barrier resin and having a thickness of 5 μm after drying. Table 1 shows the evaluation results of the obtained film.

<Reference example 1>
Table 1 shows the results of evaluating only the base film.

<Reference example 2>
A resin composition obtained by dry blending 92% by mass of base film resin with 8% by mass of an antibacterial agent is put into a co-rotating twin-screw extruder set at 210 ° C., and from the T-die connected to the tip of the co-rotating twin-screw extruder It was melt extruded, taken up with a casting roll set at 90° C., cooled and solidified to obtain a 40 μm-thick film in which the antibacterial agent was kneaded.

From the results in Table 1, the films of Examples 1 to 5 have lower oxygen permeability and higher gas barrier properties than the base film of Comparative Example 1, but the total light transmittance does not change significantly and the transparency is high. A film was obtained. In particular, the films of Examples 1 to 4 are superior in water resistance to that of Example 5, and it can be seen that the possibility of elution of the gas barrier resin is extremely low even when the films come into contact with foods containing a large amount of moisture. Furthermore, since it also exhibits antibacterial properties, it was found that a thermoplastic resin film having good appearance and having gas barrier properties, antibacterial properties, and water resistance can be obtained. Moreover, from Reference Example 2, it was found that when the antibacterial agent was kneaded by melt-kneading, many foreign matters were generated and the appearance was impaired.

Since the thermoplastic resin film of the present invention has gas barrier properties, antibacterial properties, and water resistance, it can be suitably used for food packaging films, storage containers, building materials, miscellaneous goods, home electric appliances, and the like.

Claims (10)

An antibacterial agent having a film containing a gas barrier resin (A) and an organic antibacterial agent (B) on at least one surface of the base material layer and having a film amount of 0.01 g/m ² or more and 30 g/m ² or less. sex film. 2. The antimicrobial film according to claim 1, wherein said coating is by coating. 3. The antibacterial film according to claim 1, wherein the organic antibacterial agent (B) is at least one selected from organic acid salts. Any one of claims 1 to 3, wherein the organic antibacterial agent (B) is at least one selected from the group consisting of sorbates, dehydroacetates, propionates, acetates, and benzoates. Antibacterial film according to. The antibacterial film according to any one of claims 1 to 4, wherein the gas barrier resin (A) is a polyvinyl alcohol resin. The antibacterial property according to any one of claims 1 to 5, wherein the gas barrier resin (A) and the organic antibacterial agent (B) are present in a mass ratio of 99:1 to 70:30. the film. Any one of claims 1 to 6, wherein the antibacterial performance of the film has an antibacterial activity value of 2.0 or more in an antibacterial test using baker's yeast in accordance with JIS Z2801 (2012). The antibacterial film according to the item. The antibacterial film according to any one of claims 1 to 7, which is for food packaging. A coating composition containing a gas-barrier resin (A) and an organic antibacterial agent (B), wherein the mixing ratio of the gas-barrier resin and the organic antibacterial agent is 99:1 to 70:30 by mass. coating composition. A method of forming a coating, comprising applying the coating composition according to claim 9 to a film.