Multilayer film and packaging material using the same

Abstract

An object of the present invention is to provide a multilayer film that has excellent antibacterial properties even when a small amount of antibacterial agent is used, has high transparency, and has suitable seal strength, and a packaging material using said film. [Solution] The problem is solved by a multilayer film comprising a sealing layer and an intermediate layer, wherein the sealing layer comprises linear low-density polyethylene and / or low-density polyethylene and an antibacterial agent, the intermediate layer comprises high-density polyethylene, the antibacterial agent is a metal salt of a fatty acid, and the metal of the metal salt of the fatty acid is one or more selected from lithium, sodium, potassium, rubidium, cesium, boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, silver, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, and rare earths.

Description

[Technical Field]

[0001] The present invention relates to a multilayer film having antibacterial properties and a packaging material using the same. [Background technology]

[0002] In recent years, the disposal of expired food or lost freshness fruits and vegetables has become a problem as food waste. As a result, there is a growing demand for packaging materials that can maintain the freshness and hygiene of food and extend the edible period of food. Films containing antibacterial agents are being considered as packaging materials that can extend the edible period of food.

[0003] Furthermore, the spread of various viruses and bacteria, including the novel coronavirus, has led to a growing demand throughout society for products with antibacterial and antiviral properties. Demand for these products is particularly high for items that are used frequently and are placed in places that are touched by many people, but because it takes time and money to change all existing equipment and items to ones that have antibacterial and antiviral properties, there is a demand for products that can impart these properties in a simple manner.

[0004] Known antibacterial agents that have been used to date include photocatalytic systems (such as TiO2) and metal systems (such as Ag and Cu) (for example, Patent Document 1). These metals or metal compounds are applied directly to the target object, or mixed with a binder resin to form a coating composition, which is then applied to the target object.

[0005] Currently, two methods are known for imparting antibacterial properties to packaging materials: one is to form a resin into a film and then apply an antibacterial agent to the surface that comes into contact with the contents, and the other is to knead an antibacterial agent into the resin used for the packaging material, form this into a film, and then perform secondary molding for various packaging materials. In the method of forming a resin into a film and then coating the surface of the film with an antibacterial agent, the process of applying a coating liquid containing the antibacterial agent and the process of drying the coating film are required, resulting in low production efficiency.

[0006] On the other hand, when an antibacterial agent is kneaded into a resin and then molded into a film, the antibacterial agent is contained in areas other than the surface of the film, resulting in the use of excess antibacterial agent that is not exposed to the surface and does not exert its effect. Furthermore, when inorganic metal compounds, which are conventional antibacterial agents, are kneaded into a resin, the transparency of the produced film decreases, making it difficult to see the contents. Furthermore, when a film with an antibacterial agent kneaded into a resin is used as a packaging material, the seal strength tends to be low. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-182846 Summary of the Invention [Problem to be solved by the invention]

[0008] In view of the above circumstances, an object of the present invention is to provide a multilayer film that has excellent antibacterial performance even when a small amount of antibacterial agent is used, has high transparency, and has suitable seal strength, and a packaging material using the film. [Means for solving the problem]

[0009] As a result of intensive research to solve this problem, the present inventor has found that A multilayer film comprising a seal layer and an intermediate layer, the sealing layer comprises linear low-density polyethylene and / or low-density polyethylene and an antibacterial agent; the intermediate layer comprises high density polyethylene; the antibacterial agent is a metal salt of a fatty acid; The metal of the metal salt of the fatty acid is at least one selected from lithium, sodium, potassium, rubidium, cesium, boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, silver, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, and rare earths. The present invention has been completed based on the discovery that a multilayer film characterized by the above can solve the above problems.

[0010] That is, the present invention provides a multilayer film comprising a sealing layer and an intermediate layer, wherein the sealing layer comprises linear low-density polyethylene and / or low-density polyethylene and an antibacterial agent; The present invention provides a multilayer film, characterized in that the intermediate layer contains high-density polyethylene, the antibacterial agent is a metal salt of a fatty acid, and the metal of the metal salt of a fatty acid is one or more selected from lithium, sodium, potassium, rubidium, cesium, boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, silver, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, and rare earths.

[0011] The present invention also provides a packaging material having the above multilayer film, and a packaging material for packaging food.

[0012] Furthermore, the present invention provides a laminated film and an antibacterial film having the above multilayer film. [Effects of the Invention]

[0013] The multilayer film of the present invention and the packaging material using the same can suitably achieve antibacterial properties, transparency, and seal strength all at the same time. DETAILED DESCRIPTION OF THE INVENTION

[0014] The multilayer film of the present invention and each part constituting the packaging material using the same will be described in detail below.

[0015] <Multilayer film> The multilayer film of the present invention includes a sealing layer, the sealing layer containing linear low-density polyethylene and / or low-density polyethylene and an antibacterial agent, the intermediate layer containing high-density polyethylene, the antibacterial agent being a metal salt of a fatty acid, and the metal of the metal salt of the fatty acid being one or more selected from lithium, sodium, potassium, rubidium, cesium, boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, silver, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, and rare earths.

[0016] <Sealing layer> The multilayer film of the present invention includes a sealing layer, which constitutes a surface layer on one side of the multilayer film of the present invention, is in direct contact with an article such as food to be placed inside, and is the layer that is heat-sealed when a bag is made. The sealing layer also contains an antibacterial agent and has an antibacterial effect.

[0017] The sealing layer of the multilayer film of the present invention comprises linear low density polyethylene and / or low density polyethylene, i.e., the sealing layer comprises linear low density polyethylene, low density polyethylene, or linear low density polyethylene and low density polyethylene.

[0018] The low-density polyethylene (LDPE) is 0.935 g / cm 3 By "ethylene" is meant a homopolymer of ethylene having a density less than 1000 MPa.

[0019] The linear low-density polyethylene (LLDPE) is a copolymer of ethylene monomer as the main component with α-olefins such as butene-1, hexene-1, octene-1, and 4-methylpentene as comonomers, using a low-pressure radical polymerization method with a multi-site catalyst, typically a Ziegler-Natta catalyst, or a single-site catalyst. It has a density of 0.925 g / cm. 3It refers to a linear low-density polyethylene having a comonomer content of less than 10 mol %. Therefore, it is distinguished from low-density polyethylene (LDPE), which is a homopolymer of ethylene. The comonomer content in linear low-density polyethylene is preferably in the range of 0.5 to 10 mol %, and more preferably in the range of 1 to 7 mol %. Note that the use of butene-1 as the comonomer is preferred because it improves transparency, impact resistance, tearability, etc., and in this case, the butene monomer content is most preferably in the range of 1 to 5 mol %.

[0020] Examples of the single-site catalyst include various single-site catalysts, such as metallocene catalyst systems that combine a metallocene compound of a transition metal of Group IV or V of the periodic table with an organoaluminum compound and / or an ionic compound. Single-site catalysts have uniform active sites, and therefore, compared with multi-site catalysts with non-uniform active sites, the molecular weight distribution of the resulting resin is sharper, resulting in less precipitation of low-molecular-weight components when formed into a film, and in a resin with excellent physical properties such as stable seal strength and excellent blocking resistance.

[0021] The content of the linear low-density polyethylene and / or low-density polyethylene relative to the total amount of resin components contained in the sealing layer is preferably 50% by mass to 99% by mass, more preferably 50% by mass to 95% by mass, and even more preferably 50% by mass to 90% by mass. Within this range, it is easy to achieve both sealing properties and rigidity.

[0022] The sealing layer used in the present invention may also contain a polyethylene resin other than linear low-density polyethylene and / or low-density polyethylene. Examples of the other polyethylene-based resins include medium-density polyethylene (MDPE), high-density polyethylene (HDPE), etc., which may be used alone or in combination. In this specification, polyethylene-based elastomers such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), and ethylene-α-olefin copolymer may be collectively referred to as polyethylene-based resins.

[0023] The above medium density polyethylene (MDPE) is 0.925g / cm 3 More than 0.942g / cm 3 It means a copolymer of ethylene and an α-olefin having a density of less than 1000 kJ / mol. Since the density decreases as the α-olefin used as the comonomer increases, the amount of comonomer is preferably small, and specifically, the comonomer ratio is preferably 0.5 to 1%, but is not limited to this range.

[0024] The above high density polyethylene (HDPE) is 0.942 g / cm 3 It may be a homopolymer of ethylene or a copolymer of ethylene and an α-olefin, but since the density decreases as the amount of α-olefin used as a comonomer increases, it is preferable to use a small amount of comonomer, and specifically, the comonomer ratio is preferably 0.5% or less.

[0025] In some cases, the comonomer ratio is not disclosed for commercially available products, so linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene are distinguished by density, and low-density polyethylene and medium-density polyethylene are distinguished by whether they are ethylene homopolymers or not. In the present invention, even if a product is commercially available as linear low-density polyethylene, if the density is 0.925 g / cm 3 The above can be treated as medium density polyethylene. 3If there is a polyethylene of this type, if it is an ethylene homopolymer it should be treated as low-density polyethylene, and if it is an ethylene and α-olefin copolymer it should be treated as medium-density polyethylene.

[0026] The polyethylene resin preferably has a melt flow rate (hereinafter sometimes referred to as MFR) (at 190°C) of 0.5 to 30.0 g / 10 min, as this facilitates extrusion molding, and from the viewpoint of film formability, a more preferred MFR is 2.0 to 15.0 g / 10 min. Furthermore, if the polyethylene resin has a melting point of 80 to 135°C, shrinkage of the film during heat sealing is unlikely to occur, improving packaging suitability. A melting point of 90 to 130°C is more preferred.

[0027] Furthermore, biomass-derived polyethylene may be used as the polyethylene resin, for example, biomass-derived low-density polyethylene (trade name: SBC818, density: 0.918 g / cm) manufactured by Braskem. 3 , MFR: 8.1 g / 10 min), and biomass-derived low-density polyethylene manufactured by Braskem (trade name: SPB681, density: 0.922 g / cm 3 , MFR: 3.8 g / 10 min), and Braskem biomass-derived linear low-density polyethylene (trade name: SLL118, density: 0.916 g / cm 3 , MFR: 1.0 g / 10 min).

[0028] The density of the polyethylene resin is 0.880 to 0.950 g / cm because it is easy to obtain good sealing properties and impact resistance. 3 It is preferable that the density is 0.890 to 0.945 g / cm 3 More preferably, it is 0.890 to 0.940 g / cm 3 It is more preferable that:

[0029] The content of the polyethylene resin is preferably 50% by mass or more and 99% by mass or less, more preferably 50% by mass or more and 95% by mass or less, and even more preferably 50% by mass or more and 90% by mass or less, based on the total amount of resin components contained in the sealing layer. Within this range, it is easy to achieve both sealing properties and rigidity.

[0030] The sealing layer of the present invention may further contain a polypropylene-based resin. The polypropylene-based resin refers to a propylene homopolymer or a propylene-based copolymer. The propylene-based copolymer is a copolymer of 70% to 99% by mass of propylene and 30% to 1% by mass of ethylene and / or an α-olefin having 4 or more carbon atoms, preferably a copolymer of 75% to 99% by mass of propylene and 25% to 1% by mass of ethylene and / or an α-olefin having 4 or more carbon atoms, and more preferably a copolymer of 80% to 99% by mass of propylene and 20% to 1% by mass of ethylene and / or an α-olefin having 4 or more carbon atoms. Examples of the α-olefin having 4 or more carbon atoms include 1-butene. Specific examples of the polypropylene-based resin include propylene homopolymer, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, and metallocene-catalyzed polypropylene. The polypropylene copolymer may be a random copolymer or a block copolymer. The polypropylene resin may be used alone or in combination of two or more kinds.

[0031] The polypropylene resin preferably has an MFR (at 230°C) of 0.5 to 30.0 g / 10 min and a melting point of 120 to 165°C, and more preferably an MFR (at 230°C) of 2.0 to 15.0 g / 10 min and a melting point of 125 to 162°C. If the MFR and melting point are within these ranges, the film shrinks less during heat sealing, and the film formability is also improved.

[0032] The melt flow rate (MFR) of the propylene-based resin is not particularly limited and can be appropriately selected depending on the purpose. However, under measurement conditions of a temperature of 190°C and a load of 2.16 kg, the MFR is preferably 1.0 g / 10 minutes to 50.0 g / 10 minutes, more preferably 3.0 g / 10 minutes to 45.0 g / 10 minutes, and even more preferably 3.0 g / 10 minutes to 12.0 g / 10 minutes.

[0033] The density of the propylene-based resin is not particularly limited and can be appropriately selected depending on the purpose. 3 ~0.93g / cm 3 is preferred, and 0.90 g / cm 3 ~0.92g / cm 3 is more preferred.

[0034] The melting point of the propylene resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 110°C to 170°C, more preferably 121°C to 166°C, and even more preferably 121°C to 140°C.

[0035] The resin used in the sealing layer may be used in combination with other resins as long as the effects of the present invention are not impaired. Examples of such other resins include thermoplastic elastomers such as polypropylene-based elastomers and butene-based elastomers; ethylene-based copolymers such as ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer (EMAA); and ionomers of ethylene-acrylic acid copolymers and ionomers of ethylene-methacrylic acid copolymers. When the polypropylene-based resin and other resins are used, their content is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less of the resin components contained in the sealing layer.

[0036] The resin used in the sealing layer of the present invention may contain recycled plastic.

[0037] <Antibacterial agent> The antibacterial agent used in the present invention is a metal salt of a fatty acid, and the metal in the metal salt of a fatty acid is one or more selected from lithium, sodium, potassium, rubidium, cesium, boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, silver, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, and rare earths.

[0038] The above antibacterial agent takes the form of a metal salt of a fatty acid, and due to the antibacterial properties of the metal and the high compatibility of the fatty acid with organic substances, it is thought that when added to the sealing layer of the multilayer film of the present invention, it imparts antibacterial properties to the resulting multilayer film while reducing the impact on the appearance of the multilayer film, such as the loss of transparency caused by the antibacterial agent.

[0039] In the present invention, the term "antibacterial" encompasses the effect of reducing the number of bacteria, the effect of inactivating bacteria, the effect of reducing the infectivity of bacteria, and the like.

[0040] In the present invention, the target bacteria for antibacterial treatment are not particularly limited and may be either bacteria or fungi. Examples of bacteria include gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, Salmonella, Moraxella, and Legionella; and gram-positive bacteria such as Staphylococcus aureus and Clostridium bacteria. Examples of fungi include yeasts such as Candida, Rhodotorula, and baker's yeast; and molds such as red mold and black mold.

[0041] The antibacterial agent used in the present invention will now be described.

[0042] (metal salts of fatty acids) The metal salt of a fatty acid which is the antibacterial agent used in the present invention is preferably, for example, a metal salt of a fatty acid having 2 to 31 carbon atoms. The fatty acid may have a linear, branched, or alicyclic structure.

[0043] The fatty acid having 2 to 31 carbon atoms has a carboxy group (COOH) and a fatty acid residue (carboxylic acid residue) having 1 to 30 carbon atoms. Examples of such fatty acids include saturated fatty acids and unsaturated fatty acids. More specifically, examples of saturated fatty acids include saturated fatty acids with a straight chain structure such as acetic acid, propionic acid, butanoic acid, pentanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, and melissic acid, and saturated fatty acids with a branched or alicyclic structure such as octylic acid (2-ethylhexanoic acid), neodecanoic acid, isostearic acid, naphthenic acid, and isononanoic acid. Examples of unsaturated fatty acids include monounsaturated fatty acids such as acrylic acid, methacrylic acid, palmitoleic acid, oleic acid, elaidic acid, paccenic acid, and erucic acid, and polyunsaturated fatty acids derived from vegetable oils such as tung oil acid, tall oil fatty acid, coconut oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, safflower oil fatty acid, dehydrated castor oil fatty acid, and tung oil fatty acid. One type of such fatty acid may be used alone, or two or more types may be used in combination.

[0044] Among the fatty acids having 2 to 31 carbon atoms, from the viewpoint of ease of handling the compound and the ability to suppress thermal degradation such as burning and scorching of the agent when processed into a masterbatch or pellets of a thermoplastic resin composition, as well as the resulting contamination with foreign matter (hereinafter referred to as "suppression of thermal degradation"), more preferred are one or more selected from fatty acids having 11 to 31 carbon atoms, even more preferred are one or more selected from capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, etc., and particularly preferred are one or more selected from stearic acid, palmitic acid, lauric acid, and myristic acid.

[0045] From the viewpoint of masterbatch production described below, the fatty acid of the antibacterial agent of the present invention preferably has a melting point of 25°C or higher. When the melting point of the fatty acid is 25°C or higher, it is solid in the working environment, has excellent handleability, and is suitable for masterbatch production. The melting point is more preferably 30°C or higher. Furthermore, from the viewpoint of ease of handling the compound and suppression of thermal degradation when processed into a masterbatch or pellets of the thermoplastic resin composition, the melting point of the antibacterial agent of the present invention is preferably 40° C. or higher, more preferably 50° C. or higher, and even more preferably 60° C. or higher. There are no particular limitations on the upper limit, but it is sufficient as long as it is 250° C. or lower.

[0046] More specifically, it is preferably a compound represented by the following general formula (1).

[0047] [ka] (In the general formula (1), R 1 is a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, n1 is an integer ranging from 1 to 4, M 1 is lithium, sodium, potassium, rubidium, cesium, boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, silver, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, or a rare earth.

[0048] In the general formula (1), when n1 is an integer of 2 or more, a plurality of R 1 may be the same as or different from each other.

[0049] R 1 The alkyl group having 1 to 30 carbon atoms may be a linear alkyl group, a branched alkyl group, or may contain an alicyclic structure.

[0050] R1 The hydrogen atom or alkyl group having 1 to 30 carbon atoms is used in the production of metal salts of fatty acids. 1 It corresponds to a fatty acid residue (carboxylic acid residue) obtained by removing a carboxyl group (COOH) from a carboxylic acid having 2 to 31 carbon atoms, represented by COOH. Therefore, examples of the fatty acid residue (carboxylic acid residue) include residues obtained by removing a carboxyl group from the fatty acids listed above.

[0051] R 1 The alkyl group having 1 to 30 carbon atoms is preferably an alkyl group having 10 to 30 carbon atoms, from the viewpoint of ease of handling of the compound and suppression of thermal degradation of the pelletized masterbatch and thermoplastic resin composition, more preferably a capric acid residue, lauric acid residue, myristic acid residue, palmitic acid residue, stearic acid residue, arachidic acid residue, behenic acid residue, lignoceric acid residue, cerotic acid residue, montanic acid residue, melissic acid residue, etc., and even more preferably one or more selected from a stearic acid residue, palmitic acid residue, lauric acid residue, and myristic acid residue.

[0052] M 1 is one or more selected from lithium, sodium, potassium, rubidium, cesium, boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, silver, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, or rare earths, and is preferably one or more selected from rare earths, bismuth, manganese, magnesium, calcium, lead, cobalt, or copper. From the viewpoint of reducing the occurrence of coloration due to the addition of an antibacterial agent, it is preferably one or more selected from rare earths, bismuth, magnesium, or calcium, more preferably one or more selected from bismuth, neodymium, lanthanum, praseodymium, samarium, or gadolinium, and even more preferably one or more selected from bismuth, neodymium, or lanthanum, and is particularly preferably one or more selected from neodymium or lanthanum because of particularly excellent antibacterial properties.

[0053] In the present invention, rare earth means one or more elements selected from scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0054] n1 is M 1 is a value determined by the ionic valence of the metal atom, for example, M 1 If is boron, n1 is 3, and M 1 If is cobalt, n1 is 2.

[0055] The antibacterial agent used in the present invention may contain a fatty acid metal borate, which is, for example, a compound represented by the following general formula (2):

[0056] [ka] (In the general formula (2), R 2 is a hydrogen atom or an alkyl group having 1 to 21 carbon atoms, M 2 is boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, or a rare earth.

[0057] In the general formula (2), R 2 The alkyl group having 1 to 21 carbon atoms is R 1 Similarly, in the general formula (2), M 2 The metal is M in the general formula (1). 1 It is the same as the metal.

[0058] When a metal salt of a fatty acid is used as the antibacterial agent in the present invention, the metal salt of a fatty acid may be a single type, or two or more types of metal salts of fatty acids having mutually different structures may be used.

[0059] The metal salt of a fatty acid can be produced by a known method, and a commercially available product may also be used. Examples of production methods include, but are not limited to, a method in which a metal oxide or metal hydroxide is added to a fatty acid, reacted at a predetermined temperature, and then dehydrated under reduced pressure to obtain a metal salt of the fatty acid, or a method in which a fatty acid is neutralized with sodium hydroxide, reacted with an aqueous metal chloride solution at a predetermined temperature, and then dehydrated under reduced pressure to obtain a metal salt of the fatty acid.

[0060] (metal complexes) The antibacterial agent used in the present invention may be a metal complex of a heteroatom-containing ligand and a metal ion, or a metal complex of a heteroatom-containing ligand and a fatty acid metal salt, or may be a compound in which a metal ion or a fatty acid metal salt and a heteroatom-containing ligand form a complex through a coordinate bond.

[0061] The metal ions that form the metal complex with the heteroatom-containing ligand can be the same metal ions as those in the metal salts of fatty acids explained as the antibacterial agent used in the present invention. As the metal salt of a fatty acid in which the heteroatom-containing ligand forms a metal complex, the same metal salts of a fatty acid as those explained as the antibacterial agent used in the present invention can be used.

[0062] The heteroatom-containing ligand that forms the metal complex may be a ligand that contains one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus in the molecule. Examples of such heteroatom-containing ligands include N-methylmorpholine, pyridine, 1,8-diazabicyclo[5.4.0]undecene-7 (DBU), 1,5-diazabicyclo[4.3.0]nonene-5 (DBN), 1,4-diazabicyclo[2.2.2]octane (DABCO), 4-dimethylaminoamine (DMAP), dicyandiamide (DICY), tri-n-butylamine, dimethylbenzylamine, butylamine, 1,2-propanediamine, 1,2-cyclohexanediamine, octylamine, monoethanolamine, diethanolamine, triethanolamine, 2-[[(2-dimethylamino)ethyl]methylamino]ethanol, picolinic acid, 2,2'-[propane-1,2-diylbis(azanylylidenemethanylylidene)]diphenoxyethanol alcohol, imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 2,4-dimethylimidazole, 1,4-diethylimidazole, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(N-phenyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, tetramethylammonium hydroxide, 8-quinolinol Examples of suitable amine compounds include amine compounds such as 2,2'-bipyridyl, 5-chloro-8-quinolinol, 2,2'-bipyridyl and its derivatives, 2,2'-[propane-1,2-diylbis(azanylylidenemethanylylidene)]diphenol and its derivatives, and 2,2'-methylenebis[6-(2h-benzotriazol-2-yl)-4-tert-octylphenol]; quaternary ammonium salts such as trioctylmethylammonium chloride and trioctylmethylammonium acetate; phosphine compounds such as trimethylphosphine, tributylphosphine, and triphenylphosphine; phosphonium salts such as tetramethylphosphonium chloride, tetraethylphosphonium chloride, tetrapropylphosphonium chloride, tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, trimethyl(2-hydroxypropyl)phosphonium chloride, triphenylphosphonium chloride, and benzylphosphonium chloride; and sulfur-based compounds such as thiolactic acid, 2-aminothiophenol, and 2,2'-dithiodianiline.

[0063] The heteroatom-containing ligand is preferably one or more amine ligands selected from picolinic acid, 2-{[(2-dimethylamino)ethyl]methylamino}ethanol, 1,2-propanediamine, 1,2-cyclohexanediamine, monoethanolamine, diethanolamine, triethanolamine, imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 2,4-dimethylimidazole, 1,4-diethylimidazole, 8-quinolinol, 5-chloro-8-quinolinol, 2,2′-bipyridyl and its derivatives, and 2,2′-[propane-1,2-diylbis(azanylylidenemethanylylidene)]diphenol and its derivatives.

[0064] The heteroatom-containing ligand that forms the metal complex may be of one type alone or of two or more types that are different in structure from each other.

[0065] In the metal complex, the ratio (molar ratio) of the metal ion or fatty acid metal salt to the heteroatom-containing ligand is, for example, in the range of 0.1 to 12 moles, preferably 0.3 to 10 moles, and more preferably 0.5 to 10 moles, of the heteroatom-containing ligand per mole of the metal atom of the metal ion or fatty acid metal salt.

[0066] When the metal ion in the metal complex is an aluminum ion, the aluminum complex is preferably at least one selected from aluminum chelate compounds represented by the following general formula (3-1) and aluminum chelate compounds represented by the following general formula (3-2).

[0067] [ka] (In the general formulas (3-1) and (3-2), R 311 ~R 316 and R 321 ~R 326 are each independently an alkyl group having 1 to 22 carbon atoms or an alkoxy group having 1 to 22 carbon atoms.

[0068] R 311 ~R 316 and R 321 ~R 326 The alkylene group moiety of the alkyl group having 1 to 22 carbon atoms and the alkoxy group having 1 to 22 carbon atoms may be linear or branched, or may contain an alicyclic structure. 311 ~R 316 and R 321 ~R 326 The alkyl group and the alkylene group portion of the alkoxy group preferably have 1 to 9 carbon atoms.

[0069] R 311 ~R 316 and R 321 ~R 326 The alkyl group having 1 to 22 carbon atoms is preferably a methyl group or an ethyl group.

[0070] R 311 ~R 316 and R 321 ~R 326 The alkoxy group having 1 to 22 carbon atoms is preferably a methoxy group, an ethoxy group, or an oleyloxy group.

[0071] Specific examples of aluminum chelate compounds include aluminum tris(acetylacetonate), aluminum tris(ethylacetoacetate), aluminum monoacetylacetonate bis(ethylacetoacetate), aluminum monoacetylacetonate bisoleylacetoacetate, ethylacetoacetate aluminum diisopropylate, and alkylacetoacetate aluminum diisopropylate.

[0072] The antibacterial agent used in the present invention is preferably a water-insoluble antibacterial agent. When the antibacterial agent is water-insoluble, it has excellent durability of antibacterial activity even when exposed to water such as rain. In this application, "water-insoluble" means that the amount of water required to dissolve 1 g of the antibacterial agent at 20°C is 10 mL or more.

[0073] The antibacterial agents, ie, a metal complex of a heteroatom-containing ligand and a metal ion and a metal complex of a heteroatom-containing ligand and a fatty acid metal salt, can be produced by a known method, for example, by reacting a metal or a fatty acid metal salt with a heteroatom-containing ligand. Alternatively, commercially available metal complexes may be used.

[0074] The contents of the metal salt of a fatty acid, the metal complex of the heteroatom-containing compound ligand and a metal ion, and the metal derived from the metal complex of the heteroatom-containing compound ligand and a fatty acid metal salt (hereinafter sometimes referred to as "antibacterial agent-derived metal" or simply "metal") contained in the antibacterial agent used in the present invention are not particularly limited, but are preferably 5 parts by mass or more, more preferably 7.5 parts by mass or more, and particularly preferably 10 parts by mass or more, per 100 parts by mass of the antibacterial agent. Furthermore, the contents are preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

[0075] (Masterbatch) When the antibacterial agent of the present invention is added to the sealing layer, it is preferably added in the form of a masterbatch. The masterbatch can be produced by a method including a step of blending and melt-kneading a thermoplastic resin and an antibacterial agent. More specifically, the thermoplastic resin and the antibacterial agent are blended in a predetermined blending ratio, and if necessary, premixed using a mixer such as a V-type blender, ribbon blender, or Henschel mixer. The mixture is then melt-kneaded using a known mixer such as a single-screw extrusion mixer, open-roll mixer, pressure kneader, Banbury mixer, or twin-screw extrusion mixer, with the resin set temperature set at or above the melting point. Among these, twin-screw extrusion mixers are preferred in terms of kneading ability and productivity. After melt-kneading, the masterbatch is obtained by processing the mixture into pellets or the like according to conventional methods. In the present invention, from the viewpoint of achieving both film properties and compatibility with the antibacterial agent, the thermoplastic resin is preferably the polyethylene-based resin described above, more preferably linear low-density polyethylene and / or low-density polyethylene, and even more preferably low-density polyethylene.

[0076] When producing the masterbatch, the blending ratio of the antibacterial agent may be adjusted and blended so that, for example, the antibacterial agent is preferably 0.03 parts by mass or more, more preferably 0.15 parts by mass or more, and even more preferably 0.3 parts by mass or more, and preferably 90 parts by mass or less, more preferably 75 parts by mass or less, and even more preferably 60 parts by mass or less, per 100 parts by mass of the thermoplastic resin and antibacterial agent in the masterbatch combined.

[0077] The masterbatch contains a thermoplastic resin and an antibacterial agent, and the antibacterial agent is preferably contained in an amount of 0.03 to 90 parts by mass per 100 parts by mass of the total of the thermoplastic resin and antibacterial agent in the masterbatch. The composition ratio of the thermoplastic resin and antibacterial agent contained in the masterbatch is preferably 0.03 parts by mass or more, more preferably 0.15 parts by mass or more, and even more preferably 0.3 parts by mass or more, per 100 parts by mass of the thermoplastic resin and antibacterial agent in the masterbatch combined, from the viewpoint of imparting excellent dispersibility and antibacterial properties to the molded article obtained via the masterbatch; and is preferably 90 parts by mass or less, more preferably 75 parts by mass or less, and even more preferably 60 parts by mass or less, taking into consideration the prevention of thermal degradation during processing into the masterbatch and cost benefits during transportation.

[0078] The content of the metal derived from the antibacterial agent contained in the masterbatch of the present invention is not particularly limited, but can be calculated taking into account the content of the metal contained in the antibacterial agent and the composition ratio of the antibacterial agent contained in the masterbatch. That is, the content of the metal is preferably 0.0015 parts by mass or more, more preferably 0.0075 parts by mass or more, even more preferably 0.015 parts by mass or more, and preferably 45 parts by mass or less, more preferably 37.5 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of the thermoplastic resin and antibacterial agent contained in the masterbatch combined. When the content of the metal contained in the masterbatch is within the above range, excellent dispersibility, transparency, and antibacterial properties can be imparted to a molded article obtained via the masterbatch.

[0079] (porous body) In the production of the masterbatch, a porous body may be added, which prevents excessive bleeding of the antibacterial agent and enables the antibacterial agent to be stably maintained within the masterbatch. Examples of the porous material include activated carbons such as powdered activated carbon, granular activated carbon, molecular sieve carbon, beaded activated carbon, fibrous activated carbon, high-surface-area activated carbon, molded activated carbon, and honeycomb activated carbon; aluminum porous materials such as alumina, aluminum oxide, activated alumina, boehmite gel, and zeolite; and silica porous materials such as light anhydrous silicic acid, hydrous silicon dioxide, silicon dioxide, magnesium aluminosilicate, calcium silicate, magnesium silicate, magnesium aluminum silicate, light anhydrous silicic acid-containing hydroxypropyl cellulose, diatomaceous earth, synthetic aluminum silicate, synthetic aluminum silicate-hydroxypropyl starch-crystalline cellulose, synthetic magnesium sodium silicate, colloidal hydrous aluminum silicate, and zeolite. Among these, from the viewpoints of transparency and bleed control ability, aluminum porous materials and silica porous materials are preferred, and silica porous materials are more preferred. The porous body may be a commercially available product, and examples thereof include Sylysia 250, Sylysia 320, Sylysia 350, and Sylysia 740 (manufactured by Fuji Silysia Chemical Ltd.), Adsolider 101 and Adsolider 102 (manufactured by Freund Corporation), Fluorite RE (manufactured by Tomita Pharmaceutical Co., Ltd.), Carplex #67, Carplex #80, and Carplex #101 (manufactured by DSL Japan Co., Ltd.), Aerosil 200 and Aerosil 300 (manufactured by Nippon Aerosil Co., Ltd.), and Sunsphere H-51 (manufactured by AGC Si-Tech Co., Ltd.). The porous body may be used alone or in combination of two or more types. The content of the porous body in the antibacterial masterbatch is not particularly limited, and may be adjusted so that the amount of the porous body and the amount of the antibacterial agent in the sealing layer used in the present invention are appropriate.

[0080] In addition to the thermoplastic resin and antibacterial and antiviral agent components described above, the masterbatch of the present invention may also contain various known additives as optional components within the scope of not impairing the effects of the present invention. Examples of optional additives include antiblocking agents such as silica, flame retardants such as halogen-based flame retardants, nitrogen-based flame retardants, phosphate ester-based flame retardants, inorganic flame retardants such as metal hydroxides and oxides, and silicone-based flame retardants, antioxidants such as hindered phenol compounds, hydroquinone compounds, phosphite compounds, and their substituted derivatives, weather resistance agents such as resorcinol compounds, salicylate compounds, benzotriazole compounds, benzophenone compounds, and hindered amine compounds, release agents or lubricants such as aliphatic alcohols, aliphatic amides, aliphatic bisamides, bis-urea compounds, and polyethylene wax, pigments such as phthalocyanine and carbon black, dyes such as nigrosine and aniline black, and additives such as talc, silica, kaolin, clay, and the like. Examples of the antistatic agent include crystal nucleating agents such as octyl p-oxybenzoate and N-butylbenzenesulfonamide, plasticizers such as alkyl sulfate-type anionic antistatic agents, quaternary ammonium salt-type cationic antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, and betaine-type amphoteric antistatic agents, various particulate, needle-like, and plate-like fillers such as graphite, barium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, antimony oxide, aluminum oxide, zinc oxide, iron oxide, zinc sulfide, zinc, lead, nickel, aluminum, iron, stainless steel, bentonite, montmorillonite, and synthetic mica, and reinforcing materials such as glass fiber, glass flakes, carbon fiber, boron nitride, potassium titanate, and aluminum borate.

[0081] When various additives are added as optional components, their composition ratios are not particularly limited as long as they do not impair the effects of the present invention. However, by adjusting the types and amounts of these additives, the desired functions can be freely adjusted, preferably within the range of 0.01 to 30 parts by mass per 100 parts by mass of the total of the thermoplastic resin and antibacterial agent in the masterbatch.

[0082] The method for mixing the antibacterial masterbatch and the resin used in the sealing layer of the present invention is not particularly limited, and they can be mixed by a conventionally known method. For example, they may be dry blended or melt blended. Among them, melt blending is preferred, and specifically, it is preferred to compound the antibacterial masterbatch and the resin by melt blending in a melt kneading device such as an extruder, and then pelletize the compound to produce the antibacterial masterbatch.

[0083] The content of the antibacterial agent in the sealing layer used in the present invention is preferably 0.5 to 15% by mass, more preferably 0.5 to 10% by mass, and more preferably 1 to 8% by mass. If the content of the antibacterial agent is within this range, sufficient antibacterial properties can be imparted while ensuring the properties, quality, and transparency of the multilayer film.

[0084] The sealing layer used in the present invention preferably contains the porous body. The porous body may be added to the sealing layer using the antibacterial masterbatch, or may be added to the sealing layer using a separate porous body masterbatch, or may be added directly to the resin mixture that will become the sealing layer during the production of the multilayer film. The porous body may be the same as the porous body added to the antibacterial masterbatch, and the preferred porous bodies are also the same. The content of the porous body in the sealing layer is preferably 1000 to 10000 ppm, more preferably 2000 to 7500 ppm, and even more preferably 3000 to 5000 ppm. When the content is within this range, bleeding of the antibacterial agent can be optimally controlled.

[0085] <Middle class> The multilayer film of the present invention has an intermediate layer adjacent to the seal layer. The intermediate layer contains high-density polyethylene. Other polyethylene-based resins and polypropylene-based resins may also be used in combination. The polyethylene-based resin and polypropylene-based resin may be the same as those exemplified for the seal layer. In particular, the intermediate layer preferably contains a resin having a different rigidity from that of the seal layer, more preferably contains a resin having a higher rigidity than that of the seal layer, and is more preferably a resin layer having a higher rigidity than that of the seal layer. Specifically, the polyethylene-based resin used in the intermediate layer contains high-density polyethylene, preferably contains high-density polyethylene and linear low-density polyethylene and / or low-density polyethylene, and more preferably is a mixture of high-density polyethylene and linear low-density polyethylene.

[0086] When the intermediate layer contains a resin with a different rigidity from that of the sealing layer, the difference in rigidity between the sealing layer and the intermediate layer tends to make the antibacterial agent in the sealing layer more likely to remain in the sealing layer during the extrusion molding process in film production. Furthermore, when the intermediate layer contains a resin with a higher rigidity than the sealing layer, the antibacterial agent is less likely to migrate to the intermediate layer. Furthermore, when the intermediate layer is a resin layer with a higher rigidity than the sealing layer, the antibacterial agent is even less likely to migrate to the intermediate layer. By making it more difficult for the antibacterial agent to migrate to the intermediate layer, the antibacterial function can be more efficiently exerted.

[0087] When a polyethylene-based resin containing high-density polyethylene and linear low-density polyethylene and / or low-density polyethylene is used for the intermediate layer, the high-density polyethylene-based resin has a density of 0.950 g / cm 3 High density polyethylene of 0.955 g / cm or higher is preferred, and among these, 3 Preferably, the high-density polyethylene is a high-density polyethylene having a density within the above range. When the density of the high-density polyethylene is within the above range, improved tearability and packaging suitability can be expected. Furthermore, it is preferable that the high-density polyethylene has good fluidity with an MFR (190°C) of 5 to 20 g / 10 min, because when the high-density polyethylene is melt-kneaded with the linear low-density polyethylene and / or the low-density polyethylene and extrusion-molded, it disperses relatively well and a film with a smooth surface and good transparency can be obtained.

[0088] When the polyethylene resin used for the intermediate layer contains high-density polyethylene and linear low-density polyethylene and / or low-density polyethylene, the content of the linear low-density polyethylene and / or low-density polyethylene in the intermediate layer is preferably 25 to 65% by mass, and particularly preferably 35 to 65% by mass from the viewpoint of superior tear resistance in the longitudinal and transverse directions. Furthermore, the content of the high-density polyethylene in the intermediate layer is preferably 35 to 80% by mass, and more preferably 35 to 75% by mass, from the viewpoints of transparency and smoothness and adhesive strength to layers other than the intermediate layer.

[0089] The resin used in the intermediate layer may be other resins in combination as long as the effects of the present invention are not impaired. The other resins may be the same as the other resins used in the sealing layer, and the preferred ranges are also the same.

[0090] <Other layers> The multilayer film of the present invention may contain layers other than the seal layer and the intermediate layer. Examples of the other layers include a cyclic olefin resin layer and an outermost layer.

[0091] The multilayer film of the present invention may include a cyclic olefin resin layer, which is mainly composed of a cyclic olefin resin, i.e., the cyclic olefin resin accounts for 60% by mass or more of the total mass of the cyclic olefin resin layer.

[0092] Examples of the cyclic olefin resin include norbornene polymers, vinyl alicyclic hydrocarbon polymers, and cyclic conjugated diene polymers. Among these, norbornene polymers are preferred. Norbornene polymers include ring-opening polymers of norbornene monomers (hereinafter sometimes referred to as "COP") and norbornene copolymers (hereinafter sometimes referred to as "COC") obtained by copolymerizing norbornene monomers with olefins such as ethylene. Hydrogenated products of COP and COC are particularly preferred. The weight-average molecular weight of the cyclic olefin resin is preferably 5,000 to 500,000, more preferably 7,000 to 300,000.

[0093] The norbornene monomer used as a raw material for the norbornene polymer is an alicyclic monomer having a norbornene ring. Examples of such norbornene monomers include norbornene, tetracyclododecene, ethylidenenorbornene, vinylnorbornene, ethylidetetracyclododecene, dicyclopentadiene, dimethanotetrahydrofluorene, phenylnorbornene, methoxycarbonylnorbornene, and methoxycarbonyltetracyclododecene. These norbornene monomers may be used alone or in combination of two or more.

[0094] The norbornene copolymer (COC) is a copolymer of the norbornene monomer and a copolymerizable olefin, and examples of such olefins include olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene; cycloolefins such as cyclobutene, cyclopentene, and cyclohexene; and non-conjugated dienes such as 1,4-hexadiene. These olefins can be used alone or in combination of two or more.

[0095] The content of the norbornene monomer in the norbornene copolymer (COC) is preferably 40 to 90 mol %, more preferably 50 to 80 mol %. When the content is in this range, the rigidity, tearability, and processing stability of the film are improved.

[0096] Commercially available products that can be used as the cyclic olefin resin include ring-opening polymers (COP) of norbornene monomers such as "ZEONOR" manufactured by Zeon Corporation, and norbornene copolymers (COC) such as "APEL" manufactured by Mitsui Chemicals, Inc. and "TOPAS" manufactured by TICONA.

[0097] The content of the cyclic olefin resin in the cyclic olefin resin layer is preferably 60% by mass or more, and from the viewpoint of achieving better tearability in the machine direction and the cross direction, it is preferably 80% by mass or more. The cyclic olefin resin layer may contain a resin other than the cyclic olefin resin as long as the effects of the present invention are not impaired, and the resin other than the cyclic olefin resin is not particularly limited as long as it is a resin that can be mixed with the cyclic olefin resin. For example, it may be a mixture with a low-density polyethylene resin, a mixture with a high-density polyethylene resin, or a mixture of a low-density polyethylene resin, a high-density polyethylene resin, and a cyclic polyolefin resin.

[0098] <Thickness of cyclic olefin resin layer> The thickness of the cyclic olefin resin layer is preferably 2 μm or more, more preferably 3 μm or more, and particularly preferably 5 μm or more. Furthermore, due to the cyclic olefin resin layer, the multilayer film of the present invention exhibits a water vapor barrier function even when it is thinner than multilayer films using resins other than cyclic olefin resins, making it particularly suitable for use in food packaging, etc.

[0099] Furthermore, the ratio of the cyclic olefin resin layer in the entire multilayer film of the present invention is not particularly limited, and may be adjusted so that the ratio of the cyclic olefin resin in the resin constituting the multilayer film is less than 10 mass% (i.e., 90 mass% or more of the resin constituting the multilayer film is a polyethylene resin or a polypropylene resin).

[0100] Other resins can also be used in the cyclic olefin resin layer as long as they do not impair the effects of the present invention. The other resins can be the same as the other resins used in the sealing layer, and the preferred ranges are also the same.

[0101] (outermost layer) The multilayer film of the present invention preferably includes, in addition to the sealing layer, an outermost layer as the other surface layer that is not the sealing layer. The resin used in the outermost layer preferably contains a polyethylene resin. The polyethylene resin may be any of those exemplified for the sealing layer. Low-density polyethylene and linear low-density polyethylene are preferred as the polyethylene resin because they have a good balance between tearability and pinhole resistance.

[0102] The resin used in the outermost layer may be other resins in combination as long as the effects of the present invention are not impaired. The other resins may be the same as the other resins used in the sealing layer, and the preferred ranges are also the same.

[0103] (Other additives) Other additives may be added to each of the above layers (e.g., the sealing layer, intermediate layer, cyclic olefin resin layer, outermost layer, etc.) Examples of such other additives include antioxidants, heat stabilizers, weathering stabilizers, antistatic agents, antifogging agents, antiblocking agents, lubricants, nucleating agents, release agents, ultraviolet absorbers, colorants such as pigments, biodegradation-promoting additives, and compatibilizers. When these additives are used, they are preferably used in an amount of 15 parts by mass or less, more preferably about 0.01 to 10 parts by mass, per 100 parts by mass of the resin component used in each layer. In particular, in order to impart processability during film formation and packaging suitability in a filling machine, the coefficient of friction of the outermost layer and sealing layer, which form the surface of the multilayer film, is preferably 1.5 or less, and more preferably 1.0 or less. Therefore, it is preferable to add a lubricant or an antiblocking agent to the outermost layer and sealing layer as appropriate.

[0104] <Relationship between the sealing layer and adjacent layers> In the multilayer film of the present invention, the seal layer and the intermediate layer adjacent to the seal layer preferably have different rigidities. Specifically, the intermediate layer adjacent to the seal layer preferably has a higher rigidity than the seal layer. If the intermediate layer adjacent to the seal layer has a higher rigidity than the seal layer, the antibacterial agent in the seal layer is less likely to migrate to the adjacent intermediate layer during extrusion production of the multilayer film of the present invention, and even a small amount of the antibacterial agent can more efficiently exhibit antibacterial properties. The multilayer film of the present invention uses linear low-density polyethylene and / or low-density polyethylene in the sealing layer and a highly rigid resin such as high-density polyethylene in the intermediate layer adjacent to the sealing layer, so that it exhibits antibacterial properties more efficiently even with a small amount of antibacterial agent.

[0105] In the multilayer film of the present invention, the difference in resin density between the seal layer and the intermediate layer is 0.005 g / cm 3 It is preferable that the density is 0.010 g / cm or more. 3 It is more preferable that the difference in resin density between the seal layer and the intermediate layer adjacent to the seal layer is within this range. When the difference in resin density between the seal layer and the intermediate layer adjacent to the seal layer is within this range, the antibacterial agent in the seal layer is less likely to migrate to the adjacent intermediate layer during extrusion production of the multilayer film of the present invention, and antibacterial properties can be more efficiently exhibited even with a small amount of antibacterial agent. Note that the resin density of each layer is a value that can be calculated from the density of that resin when the layer is composed of one type of resin, or from the density of each resin and the weighted average of the composition ratio of each resin when the layer is composed of multiple resins.

[0106] (Layer structure of multilayer film) The multilayer film of the present invention comprises a seal layer and an intermediate layer, the intermediate layer being adjacent to the seal layer.

[0107] Examples of the layer structure of the multilayer film include, but are not limited to, outermost layer / intermediate layer / sealing layer, outermost layer / intermediate layer / intermediate layer / sealing layer, outermost layer / cyclic olefin-based resin layer / intermediate layer / sealing layer, and outermost layer / intermediate layer / cyclic olefin-based resin layer / intermediate layer / sealing layer. It is also preferable that the outermost layer / intermediate layer / sealing layer be laminated.

[0108] The thickness of the sealing layer of the present invention is preferably 2.0 μm to 20 μm, and more preferably 2.5 μm to 15 μm. The thickness of the intermediate layer and the cyclic olefin resin layer is preferably 2 μm or more, and more preferably 5 μm or more. The thickness of the outermost layer is preferably 10 to 40 μm from the viewpoint of film properties.

[0109] The thickness of the sealing layer is preferably in the range of 5 to 20% of the total thickness of the multilayer film of the present invention, more preferably 5 to 15%. When the ratio of the thickness of the sealing layer to the total thickness of the multilayer film is in this range, the antibacterial agent is likely to exhibit its full effect and the sealing property is also good. The thickness of the intermediate layer is preferably in the range of 10 to 40% of the total thickness of the multilayer film of the present invention, and more preferably 15 to 35%. When the ratio of the thickness of the intermediate layer to the total thickness of the multilayer film is in this range, the transparency, tearability, pinhole resistance, and heat sealability are improved. The thickness of the outermost layer is preferably 30 to 80%, more preferably 35 to 75%, of the total thickness of the multilayer film of the present invention, from the viewpoints of film rigidity, suitability for packaging, transparency, surface gloss, and ease of tearing in the lateral direction.

[0110] Furthermore, the multilayer film of the present invention preferably has a film thickness of 15 to 90 μm, more preferably 20 to 80 μm. If the film thickness is within this range, stable seal strength, suitability for packaging machines, excellent pinhole resistance, easy tearing properties, etc. can be obtained.

[0111] The multilayer film of the present invention preferably contains polyethylene resin in an amount of 90% by mass or more of the resin constituting the multilayer film. Such a multilayer film is also called a mono-material film, and has good recyclability. As the polyethylene resin, the polyethylene resins listed above for the sealing layer can be used, and these may be used alone or in combination of two or more.

[0112] (Manufacturing method of multilayer film) The method for producing the multilayer film of the present invention is not particularly limited, but examples include a coextrusion method in which the resins or resin mixtures used for the outermost layer, intermediate layer, and seal layer are heated and melted in separate extruders, laminated in the molten state in the order of outermost layer / intermediate layer / seal layer by a method such as a coextrusion multilayer die method or a feed block method, and then formed into a film by an inflation method or a T-die / chill roll method. This coextrusion method is preferred because it allows relatively free adjustment of the thickness ratio of each layer and produces a multilayer film that is excellent in hygiene and cost performance. Furthermore, due to the large difference in softening point (melting point) between the low-density polyethylene and / or linear low-density polyethylene used in the intermediate layer of the present invention and the high-density polyethylene, phase separation and gelation may occur. To suppress the occurrence of such phase separation and gelation, a T-die method, which allows melt extrusion at a relatively high temperature, is preferred.

[0113] When the resin mixture is laminated to each layer, the dry-blended resin mixture can be directly extruded using a co-extruder for lamination. Alternatively, the resin mixture can be melt-blended in advance using a melt-kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer, and then pelletized and extruded using a co-extruder for lamination.

[0114] The multilayer film of the present invention can be obtained as a substantially unstretched multilayer film by the above-mentioned production method, and therefore can be subjected to secondary forming such as deep drawing by vacuum forming.

[0115] Immediately after extrusion of the outermost layer or the sealing layer, the layer may be brought into contact with a roll having projections and recesses to be embossed.

[0116] Furthermore, to improve adhesion to printing ink and lamination suitability, it is preferable to subject the outermost layer to a surface treatment, such as a corona treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, or ozone / ultraviolet treatment, or a surface roughening treatment such as sandblasting, with corona treatment being preferred.

[0117] (Laminate) The multilayer film of the present invention can be laminated with a substrate by bonding, coating, or the like to form a laminate having the multilayer film of the present invention. The laminate of the present invention may have the following structure: (1) Substrate / Adhesive Layer / Multilayer Film of the Present Invention (2) Substrate / Adhesive Layer / Printing Layer / Multilayer Film of the Present Invention (3) Substrate / adhesive layer / second substrate / printed layer / adhesive layer / multilayer film of the present invention (4) Substrate / Adhesive Layer / First Printed Layer / Second Printed Layer / Multilayer Film of the Present Invention (5) Substrate / Adhesive Layer / Barrier Layer / Adhesive Layer / Multilayer Film of the Present Invention (6) Substrate / Adhesive Layer / Barrier Layer / Printing Layer / Adhesive Layer / Multilayer Film of the Present Invention (7) Substrate / printing layer / adhesive layer / multilayer film of the present invention (8) Substrate / first printed layer / second printed layer / adhesive layer / multilayer film of the present invention (9) Substrate / printing layer / adhesive layer / barrier layer / adhesive layer / multilayer film of the present invention (10) Substrate / adhesive layer / barrier layer / adhesive layer / second substrate / adhesive layer / multilayer film of the present invention (11) Substrate / printing layer / adhesive layer / barrier layer / adhesive layer / second substrate / adhesive layer / multilayer film of the present invention (12) Adhesive layer / multilayer film of the present invention The examples include, but are not limited to, and may further include additional substrates. When multiple adhesive layers are included, each adhesive layer may have the same composition or different adhesive layers, and the thickness of the multiple adhesive layers may be the same or different, and is not particularly limited. The second and additional substrates may be unstretched resin films, stretched resin films, metal-deposited films such as metal-deposited unstretched films and metal-deposited stretched films, or transparent vapor-deposited films, and are not particularly limited. Furthermore, the adhesive layers may have the same composition or different compositions. Furthermore, in order to improve the adhesive strength of the adhesive layer, an anchor coat layer may be sandwiched between the layers. Furthermore, the substrate may have a coating layer on it that provides functions such as release properties and antistatic properties.

[0118] (base material) The substrate is not particularly limited, and examples thereof include polyolefin films such as polyethylene terephthalate (PET) film, polybutylene terephthalate (PBT) film, polystyrene film, polyamide film, nylon film, polyacrylonitrile film, polyethylene film (OPE: biaxially oriented polyethylene film, LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film) and polypropylene film (CPP: unoriented polypropylene film, OPP: biaxially oriented polypropylene film), polyvinyl alcohol film, ethylene-vinyl alcohol copolymer film, cellophane, etc.

[0119] Films laminated with an inorganic vapor-deposited layer of a metal oxide such as silica or alumina can also be used. Specific examples include OPE, OPP, PET, PBT, and nylon films with a silica vapor-deposited layer, and OPE, OPP, PET, PBT, and nylon films with an alumina vapor-deposited layer.

[0120] When mono-material packaging is considered, a film made of a thermoplastic resin primarily composed of an olefin-based resin can be used as the substrate. Specific examples of olefin-based resins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; polypropylene; ethylene-propylene copolymers; α-olefin polymers; ethylene-vinyl acetate copolymers; ethylene-vinyl alcohol copolymers; ethylene-acrylic acid copolymers; ethylene-methyl methacrylate copolymers; ethylene-ethyl acrylate copolymers; cyclic olefin resins; ionomer resins; and polymethylpentene; as well as modified olefin-based resins obtained by modifying olefin resins with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids. By using the above-mentioned polyethylene as the substrate, the multilayer film of the present invention can be made into a polyethylene mono-material film, which is preferable for reducing environmental impact.

[0121] It is also preferable to use a film formed from a material containing biomass-derived components as the film substrate. Biomass films are commercially available from various companies, and for example, films and sheets such as those listed in the list of biomass-certified products listed by the Japan Organics Recycling Association can be used.

[0122] Specifically, well-known films are made from biomass-derived ethylene glycol. Biomass-derived ethylene glycol is made from ethanol (biomass ethanol) produced from biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol into ethylene oxide by a conventionally known method to produce ethylene glycol. Alternatively, commercially available biomass ethylene glycol may be used; for example, biomass ethylene glycol commercially available from India Glycoal Limited can be suitably used.

[0123] Alternatively, products made from biomass materials classified by the biomass plastic content specified by ISO 16620 or ASTM D6866 are also available. Radioactive carbon-14C exists in the atmosphere at a ratio of 1 in 1012 particles, and this ratio is the same for atmospheric carbon dioxide, so this ratio remains the same even in plants that fix this carbon dioxide through photosynthesis. Therefore, the carbon in plant-derived resins contains radioactive carbon-14C. In contrast, the carbon in fossil fuel-derived resins contains almost no radioactive carbon-14C. Therefore, by measuring the concentration of radioactive carbon-14C in the resin using an accelerator mass spectrometer, the plant-derived resin content, i.e., the biomass plastic content, can be determined. Examples of plant-derived low-density polyethylene that is a biomass plastic having a biomass plastic content of 80% or more, preferably 90% or more as specified by ISO 16620 or ASTM D6866 include products manufactured by Braskem under the trade names "SBC818," "SPB608," "SBF0323HC," "STN7006," "SEB853," and "SPB681," and films using these as raw materials can be suitably used.

[0124] For example, as an alternative to conventional polyolefin films made from petroleum-based raw materials, biomass polyolefin films such as biomass polyethylene films and biomass polyethylene-polypropylene films containing ethylene resins made from biomass-derived ethylene glycol are also known. The ethylene-based resin is not particularly limited except that ethylene glycol derived from the biomass is used as part of the raw material, and examples thereof include ethylene homopolymers and copolymers of ethylene and α-olefins with ethylene as the main component (ethylene-α-olefin copolymers containing 90% by mass or more of ethylene units), and these can be used alone or in combination of two or more. The α-olefin constituting the copolymer of ethylene and α-olefin is not particularly limited, and examples thereof include α-olefins having 4 to 8 carbon atoms, such as 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Known polyethylene resins, such as low-density polyethylene resin, medium-density polyethylene resin, and linear low-density polyethylene resin, can be used. Among them, linear low-density polyethylene resin (LLDPE) (a copolymer of ethylene and 1-hexene or a copolymer of ethylene and 1-octene) is preferred from the viewpoint of making it more difficult for damage such as holes or tears to occur even when films are rubbed against each other, and has a density of 0.910 to 0.925 g / cm 3 More preferred is a linear low density polyethylene resin in which

[0125] The biomass film may be a laminate of multiple biomass films, or may be a laminate of a conventional petroleum-based film and a biomass film.

[0126] The substrate may be one that has been subjected to some kind of surface treatment, for example, a physical treatment such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, or flame treatment, or a chemical treatment such as oxidation treatment using chemicals, or other treatment.

[0127] The substrate can be produced from the resins described above by a conventionally known film-forming method such as extrusion, cast molding, T-die molding, cutting, inflation, etc. The substrate may be an unstretched film, or may be one that has been stretched uniaxially or biaxially using a tenter system, tubular system, or the like, from the viewpoint of film strength, dimensional stability, and heat resistance.

[0128] The substrate may contain additives as needed. Specifically, plastic compounding agents and additives such as elastomers, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, and pigments may be added for the purpose of improving or modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, mold releasability, flame retardancy, mildew resistance, electrical properties, strength, etc. The amount of additive added is adjusted within a range that does not affect other performance properties or recyclability.

[0129] The thickness of the substrate is not particularly limited and may be appropriately selected in the range of 0.1 to 300 μm from the viewpoints of formability and transparency. The thickness is preferably in the range of 0.3 to 100 μm. If the thickness of the substrate is 0.1 to 300 μm, good strength and processing stability can be obtained.

[0130] From the viewpoint of recycling, it is preferable that the layer structure is as simple as possible, but from the viewpoint of the distribution of the packaging material, it may include printing to display the contents of the packaging material or a description or name of the product.

[0131] (Adhesive layer) In the present invention, the adhesive layer functions to bond any two layers constituting the laminate, for example, the base layer and the second base layer. The adhesive used in the adhesive layer may be any adhesive that can be used in a general-purpose lamination method. Examples of lamination methods include dry lamination, wet lamination, non-solvent lamination, extrusion lamination, sand lamination, and thermal lamination. After the adhesive hardens or dries, it becomes an adhesive layer.

[0132] The adhesive used in the dry lamination may be, for example, a one-component or two-component curing or non-curing vinyl, (meth)acrylic, polyamide, polyester, polyether, polyurethane, epoxy, rubber, or other solvent-based, water-based, or emulsion-based adhesive. A two-component curing adhesive made of a polyol and an isocyanate compound may be used. Of the above adhesives, two-component curing adhesives of a polyol composition and a polyisocyanate composition are preferred.

[0133] (two-component curing adhesive) The two-component curing adhesive preferably contains a polyisocyanate composition (X) and a polyol composition (Y).

[0134] (Polyisocyanate composition (X)) The polyisocyanate composition (X) is not particularly limited, and any polyisocyanate composition (X) used in the adhesives technical field can be used. For example, a urethane prepolymer, a mixture of a urethane prepolymer and an isocyanate compound, or an isocyanate compound can be used.

[0135] The two-component curing adhesive may be a commercially available product, such as DIC Graphics Corporation's DIC Dry LX-500 / KW-75, DIC Dry LX-520 / KO40, DIC Dry LX-703VL / KR-90, DIC Dry LX-732 / KVM-90, DIC Dry LX-906 / KO55, DIC Dry LX-963 / KO-40, and DIC Dry LX-901 / KW-75; and Toyo Ink Co., Ltd.'s TM-250HV / CAT-RT86, TM-595 / CAT-56, TM-265L / CAT-RT37, AD-502 / CAT-10, AD-556 / CAT-56, AD-811 / CAT-RT8, AD-817 / CAT-RT56, and AD-900 / CAT T-RT85, etc., Takelac A-310 / Takenate A-3, Takelac A-315 / Takenate A-10, Takelac A-385 / Takenate A-50, Takelac A-515 / Takenate A-50, Takelac A-520 / Takenate A-50, Takelac A-525 / Takenate A-52, Takelac A-606 / Takenate manufactured by Mitsui Chemicals, Inc. Examples of suitable combinations of adhesives and curing agents include Takelac A-10, Takelac A-620 / Takenate A-65, Takelac A-626 / Takenate A-50, Takelac A-627 / Takenate A-65, and Takelac A-975 / Takenate A-3, as well as Seikabond E-366 / C-83, E-370 / C-84, E-372 / C-76, and A601 / C84 manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd. Examples of suitable combinations of polyether adhesives and curing agents include DIC Graphics' Dickdry LX-401A / SP-60 and Dickdry LE-3100 / SL-75, as well as Seikabond A-159 / C-89F, both manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd. Examples of polyurethane adhesives include one-component moisture-curing polyurethane resins (trade name: Unoflex series) and two-component curing polyurethane resins (trade name: Polybond series) manufactured by Sanyo Chemical Industries, Ltd. Alternatively, commercially available biomass adhesives can also be preferably used. As commercially available products, adhesives listed in the Japan Organics Resources Association can be used, such as DIC Dry BM (manufactured by DIC Corporation) and Takenate BM (manufactured by Mitsui Chemicals, Inc.).

[0136] The weight of the adhesive layer after drying is 0.1 to 10 g / m 2 It is preferable that the amount is 1 to 6 g / m 2 More preferably, it is 2 to 5 g / m 2 It is more preferable that:

[0137] The thickness of the adhesive layer is preferably 0.1 to 10 μm, more preferably 1 to 7 μm, and even more preferably 2 to 5 μm.

[0138] The adhesive may be a functional adhesive. For example, as an adhesive having gas barrier properties, the oxygen barrier adhesive PASLIM series manufactured by DIC Corporation, which is a two-component curing adhesive of polyester polyol and isocyanate compound, can be used. After the gas barrier adhesive is cured or dried, it becomes a gas barrier adhesive layer. Use of a gas barrier adhesive is preferred because it can further enhance the gas barrier properties of the laminate of the present invention.

[0139] Various pressure-sensitive adhesives can be used as the adhesive, and it is preferable to use a pressure-sensitive adhesive. Examples of pressure-sensitive adhesives include rubber-based adhesives obtained by dissolving polyisobutylene rubber, butyl rubber, or mixtures thereof in organic solvents such as benzene, toluene, xylene, or hexane; or these rubber-based adhesives blended with tackifiers such as abiethylene acid rosin ester, terpene-phenol copolymer, or terpene-indene copolymer; and acrylic-based adhesives obtained by dissolving acrylic copolymers with a glass transition temperature of -20°C or less, such as 2-ethylhexyl acrylate-n-butyl acrylate copolymer or 2-ethylhexyl acrylate-ethyl acrylate-methyl methacrylate copolymer, in an organic solvent.

[0140] The adhesive can be applied by, for example, direct gravure roll coating, gravure offset roll coating, kiss coating, reverse roll coating, Fountain coating, transfer roll coating, or other methods.

[0141] When the adhesive is a solvent-based adhesive, the adhesive can be applied to one of the substrates using a roll such as a gravure roll, and the organic solvent can be evaporated by heating in an oven or the like, and then the other substrate can be attached to obtain the laminate of the present invention. After lamination, it is preferable to carry out an aging treatment. The aging temperature is preferably from room temperature to 80°C, and the aging time is preferably from 12 to 240 hours.

[0142] When the adhesive is a solventless type, the adhesive, which has been preheated to about 40°C to 100°C, is applied to one of the substrates using a roll such as a gravure roll, and then the other substrate is immediately bonded to the adhesive to obtain the laminate of the present invention. After lamination, it is preferable to carry out an aging treatment. The aging temperature is preferably from room temperature to 70°C, and the aging time is preferably from 6 to 240 hours.

[0143] The amount of adhesive to be applied is adjusted as appropriate. For example, in the case of solvent-based paints, the solid content is 1 g / m 2 More than 10g / m 2 Less than 1 g / m 2 More than 5g / m 2 Adjust it so that it is as follows: For solvent-free adhesives, the amount of adhesive applied is, for example, 1 g / m 2 More than 10g / m 2 Less than 1 g / m 2 More than 5g / m 2 The following is the result.

[0144] (thermoplastic resin) The adhesive layer can also be formed from a thermoplastic resin, and can be formed by a conventionally known method, such as extrusion lamination or sand lamination. Examples of the thermoplastic resin that can be used for the adhesive layer include ethylene-based resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE); propylene-based resins such as propylene homopolymers, propylene-α-olefin random copolymers, and propylene-α-olefin block copolymers; norbornene-based polymers and hydrogenated products thereof, such as norbornene-based copolymers (COC) obtained by copolymerizing norbornene-based monomers with olefins such as ethylene; vinyl alicyclic hydrocarbon polymers; and cyclic polyolefin-based resins such as cyclic conjugated diene polymers. Examples of the elastomer include polyethylene-based elastomers such as vinyl acetate copolymer (EVA) and ethylene-α-olefin copolymer, polypropylene-based elastomers, and butene-based elastomers; ethylene-based copolymers such as ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer (EMAA); and further ionomers of ethylene-acrylic acid copolymer and ionomers of ethylene-methacrylic acid copolymer. In addition, in order to improve the adhesion between layers, acid-modified polyolefin resins obtained by modifying the above-mentioned polyolefin resins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid can also be used. Furthermore, resins obtained by graft polymerizing or copolymerizing a polyolefin resin with an unsaturated carboxylic acid, an unsaturated carboxylic anhydride, or an ester monomer can also be used. These resins may be used alone or in combination of two or more. It is also preferable to use, as the ethylene-based resin, one that uses ethylene derived from biomass as a monomer unit.

[0145] When the adhesive layer is laminated by extrusion lamination, an anchor coating layer may be provided on the surface of the layer to be laminated by applying an anchor coating agent and drying it. Examples of anchor coating agents include anchor coating agents made from any resin with a heat resistance temperature of 135°C or higher, such as polybutadiene resin, urethane resin, polyisocyanate-polyether polyol, polyethyleneimine, vinyl-modified resin, epoxy resin, polyester resin, alkyl titanate, etc., as well as anchor coating agents made by diluting the above adhesives with organic solvents. Among these, polyethyleneimine-based anchor coating agents and anchor coating agents prepared by diluting the above adhesives with organic solvents are preferably used. A silane coupling agent may be used in combination with this as an additive, and soluble nitrocellulose may be used in combination to enhance heat resistance.

[0146] When the laminate of the present invention is obtained by laminating the multilayer film of the present invention and a substrate or the like by extrusion lamination or sand lamination, the nip roll or chill roll used during lamination may be replaced with an embossing roll to emboss the surface on the seal layer side.

[0147] (Printing layer) The print layer is a layer on which characters, figures, symbols, and other desired designs are printed. There are no particular limitations on the printing method or printing ink, and any known printing method or printing ink can be used. For the films used as the substrates, printing inks are often used in gravure printing, flexographic printing, lithographic offset printing, ink jet recording printing, and the like. Printing inks that combine these printing methods with methods of curing using active energy rays such as ultraviolet (UV), LED, and electron beam (EB), or methods of curing using heat, are also used. Depending on the solvent used, it may also be referred to as water-based ink or organic solvent-based ink.

[0148] Specific examples include gravure printing ink and flexographic printing ink (in some industries, gravure printing ink and flexographic printing ink are sometimes referred to as liquid printing ink), ultraviolet-curable ink for lithographic offset printing, electron-beam-curable ink for lithographic offset printing, ultraviolet-curable ink for inkjet recording and printing, and electron-beam-curable ink for inkjet recording and printing. Furthermore, the ink may be a biomass ink made from biomass raw materials, or an ink made from recycled raw materials.

[0149] The position at which the printed layer printed using these inks is provided is arbitrary, and it may be provided on the above-mentioned substrate, or a substrate on which a separate printed layer is provided may be one of the constituent components of the laminate of the present invention, and the position is arbitrary. The ink may contain a resin, a colorant, and a solvent as essential components, or may be a so-called clear ink that contains a resin and a solvent but does not substantially contain a colorant.

[0150] (barrier layer) The laminate of the present invention may include a barrier layer. Examples of the barrier layer include an aluminum layer, a vapor deposition layer, and a gas barrier resin layer.

[0151] For applications that do not require transparency, aluminum layers made of aluminum foil can be used alone or in combination as the barrier layer.

[0152] (deposited layer) The laminate of the present invention may be provided with a vapor-deposited layer made of an inorganic substance and / or an inorganic oxide as a barrier layer. By using the vapor-deposited layer, it is possible to impart barrier properties to the laminate of the present invention. The vapor-deposited layer can be formed by a known method using a known inorganic substance or inorganic oxide, and the composition and method of formation thereof are not particularly limited. The laminate of the present invention may have two or more vapor-deposited films, which may have the same composition or different compositions.

[0153] The vapor-deposited layer may be, for example, a vapor-deposited film of an inorganic substance or inorganic oxide such as silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), or yttrium (Y). Furthermore, vapor-deposited films of inorganic oxides such as silicon oxide and aluminum oxide are transparent.

[0154] The inorganic oxides are expressed as MOx (wherein M represents an inorganic element), such as SiOx and AlOx. The value of x can range from 0 to 2 for silicon (Si), 0 to 1.5 for aluminum (Al), 0 to 1 for magnesium (Mg), 0 to 1 for calcium (Ca), 0 to 0.5 for potassium (K), 0 to 2 for tin (Sn), 0 to 0.5 for sodium (Na), 0 to 1.5 for boron (B), 0 to 2 for titanium (Ti), 0 to 1 for lead (Pb), 0 to 2 for zirconium (Zr), and 0 to 1.5 for yttrium (Y). In the above, when x=0, it is a completely inorganic element (pure substance) and is not transparent, and when the value of x is at the upper limit of the range, it indicates that it is completely oxidized. Silicon (Si) or aluminum (Al) is preferably used for the vapor deposition layer, and silicon (Si) with an x ​​value in the range of 1.0 to 2.0 and aluminum (Al) with an x ​​value in the range of 0.5 to 1.5 can be used.

[0155] The vapor deposition layer can be formed on the surface of the substrate or the like by a physical vapor deposition method (PVD method) such as vacuum deposition, sputtering, or ion plating, or a chemical vapor deposition method (CVD method) such as plasma chemical vapor deposition, thermal chemical vapor deposition, or photochemical vapor deposition.

[0156] The thickness of the vapor-deposited layer is not particularly limited as long as the vapor-deposited layer alone can exhibit a certain level of gas barrier function. The preferred range of thickness varies depending on the type of metal or metal oxide to be deposited, but is preferably 0.05 to 70 nm, more preferably 0.1 to 70 nm, even more preferably 3 to 70 nm, and even more preferably 5 to 60 nm.

[0157] The vapor-deposited layer may be a metal vapor-deposited film. As the metal-deposited film, a VM-CPP film in which a metal such as aluminum is deposited on a CPP film, or a VM-OPP film in which a metal such as aluminum is deposited on an OPP film can be used. Examples of the transparent vapor-deposited film include films obtained by depositing silica or alumina onto OPP film, PET film, nylon film, or the like. For the purpose of protecting the inorganic vapor deposition layer of silica or alumina, a film having a coating applied on the vapor deposition layer may be used.

[0158] (gas barrier resin layer) The gas barrier resin layer can be obtained by applying a known gas barrier coating agent containing, for example, a vinyl alcohol polymer and an aqueous solvent by a known coating method to form a coating film. The coating method is not particularly limited, and examples that can be used include spraying, spin coating, dipping, roll coating, blade coating, doctor roll coating, doctor blade coating, curtain coating, slit coating, screen printing, inkjet printing, dispensing, die coating, direct gravure, reverse gravure, flexography, knife coating, and dot coating.

[0159] (Adhesive layer) The adhesive layer contains a pressure-sensitive adhesive and has the function of adhering to an adherend. Known pressure-sensitive adhesives can be used as the pressure-sensitive adhesive, such as acrylic pressure-sensitive adhesives, urethane pressure-sensitive adhesives, synthetic rubber pressure-sensitive adhesives, and silicone pressure-sensitive adhesives. These may be used alone or in combination of two or more. Removable pressure-sensitive adhesives may also be used.

[0160] The acrylic pressure-sensitive adhesive may contain acrylic monomers as constituent monomers, or may contain non-acrylic monomers. However, the proportion of acrylic monomers in all monomers constituting the acrylic pressure-sensitive adhesive is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0161] Specific examples of urethane-based adhesives include reaction products of polyester polyol or polyether polyol with polyisocyanate compounds.

[0162] Specific examples of synthetic rubber-based adhesives include styrene-butadiene rubber, polyisobutylene rubber, isobutylene-isoprene rubber, styrene-isoprene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene block copolymer, and styrene-ethylene-butylene block copolymer.

[0163] Specific examples of silicone-based pressure-sensitive adhesives include compositions containing silicone rubber and silicone resin.

[0164] The adhesive layer may contain additives other than the adhesive, such as ultraviolet absorbers, fillers, softeners, modifiers, antioxidants, light stabilizers, heat stabilizers, polymerization inhibitors, crosslinking agents, colorants, rust inhibitors, flame retardants, hydrolysis inhibitors, surface lubricants, corrosion inhibitors, lubricants, antistatic agents, catalysts, leveling agents, thickeners, dispersants, antifoaming agents, surfactants, etc.

[0165] When a laminate including an adhesive layer is used, the adhesive layer may be further protected with a release liner, which can prevent adhesion to undesired areas and adhesion of dust and the like.

[0166] The adhesive layer is formed on the outermost layer side (the surface opposite to the seal layer side) of the multilayer film of the present invention. The method for forming the adhesive layer is not particularly limited, and it can be formed by a known method. For example, it can be formed by applying a liquid adhesive composition (coating liquid) to the film substrate 1 by various coating methods such as roll coating, gravure coating, reverse coating, knife coating, die coating, comma coating, and bar coating. The adhesive layer 2 can be formed by solidifying the coating film of the coating liquid. Alternatively, the adhesive layer may be formed on a release liner first, and then laminated to the multilayer film of the present invention.

[0167] The laminate of the present invention can be suitably used as a material having antibacterial activity for components that come into contact with human hands, etc. For example, it can be used in a wide range of applications, including the exterior of smartphones, the exterior of personal computers, optical displays such as touch panels, handrails, doorknobs, washbasins, modular baths, windows, push buttons such as elevator buttons, interior furnishings (wallpaper, flooring, cushion flooring, flooring, decorative panels, etc.), housings for air purifiers and air conditioners, antibacterial cover films for automobile interiors, and hygiene products such as face shields and gloves. In this case, a laminate in which an adhesive layer is laminated on the multilayer film of the present invention is preferred because it can be easily attached to the adherend such as the member. The laminate of the present invention is preferred because it has high transparency and therefore does not impair the appearance even when attached to the adherend such as the member.

[0168] (packaging material) The multilayer film of the present invention can be suitably used as a packaging material, such as a packaging bag or container for food, medicine, etc.

[0169] The packaging bag is preferably one formed by overlapping and sealing the sealing layers of the multilayer film of the present invention, or by overlapping and sealing the outermost layer and the sealing layer. For example, two sheets of the multilayer film are cut to the desired size of the packaging bag, overlapped, and sealed on three sides to form a bag, and then the contents are filled in through the unsealed side and sealed. Furthermore, a packaging bag can be formed by sealing the ends of a rolled film into a cylindrical shape using an automatic packaging machine, and then sealing the top and bottom.

[0170] The multilayer film of the present invention can also be used to form packaging bags and containers by overlapping and sealing the seal layer used in the present invention with another sealable film. In this case, a film with relatively low mechanical strength, such as LDPE or EVA, can be used as the other film. A laminate film can also be used, in which a film such as LDPE or EVA is bonded to an oriented film with relatively good tearability, such as a biaxially oriented polyethylene terephthalate film (OPET) or a biaxially oriented polypropylene film (OPP). Because the multilayer film of the present invention is a monomaterial film with excellent recyclability, the other film to be bonded by sealing or laminating is preferably a polyethylene resin such as LDPE.

[0171] The multilayer film of the present invention has heat-sealing properties and can be used to form packages by heat sealing. The heat-sealing strength of the multilayer film of the present invention can be adjusted appropriately depending on the intended use. For example, the multilayer film of the present invention is heat-sealed to an A-PET sheet (softening point 77°C, crystallization temperature 126°C) at a temperature of 170°C and a pressure of 0.2 MPa for 1.0 second, and then a 15 mm wide test piece is cut out. The maximum load when peeled in a 180° direction at a pulling rate of 300 mm / min in a thermostatic chamber at 23°C and 50% RH is preferably 3 N / 15 mm or more, more preferably 6 N / 15 mm or more. The upper limit of the maximum load is preferably less than 20 N / 15 mm, more preferably less than 15 N / 15 mm. By achieving this peel strength, the multilayer film is less likely to peel or fall off, and is particularly easy to open. In addition to heat sealing, the multilayer film of the present invention can also be sealed by ultrasonic waves. There are no particular limitations on the method of ultrasonic sealing, and any known ultrasonic sealing method or method using a known ultrasonic sealing device can be appropriately selected depending on the purpose.

[0172] Furthermore, the laminate of the present invention, which is a laminate film structure using the multilayer film of the present invention or the above-mentioned substrate as a sealant, can be suitably used as a packaging material for food, pharmaceuticals, industrial parts, miscellaneous goods, building materials, magazines, etc. When used as a packaging material, the layer structure can be changed depending on the contents, usage environment, and usage form. Furthermore, the package of the present invention may be appropriately provided with an easy-open treatment or resealing means. The sealing surface may be the sealing layer of the multilayer film of the present invention or the substrate located in the outermost layer of the laminate. Packaging materials made of laminates containing the multilayer film of the present invention have good sealing properties and transparency, and have antibacterial properties on the surface of the sealing layer side, so they are particularly suitable for use as packaging materials for packaging food.

[0173] The packaging material of the present invention can be obtained, for example, by overlapping the laminate of the present invention with the surfaces facing each other and then heat-sealing the peripheral edges to form a bag. Examples of bag-making methods include folding or overlapping the laminate of the present invention with the surfaces of the inner layers (sealant layer surfaces) facing each other, and heat-sealing the peripheral edges using, for example, a side seal, two-sided seal, three-sided seal, four-sided seal, envelope seal, flared seal, flat-bottom seal, square-bottom seal, gusset seal, or other heat seal methods. The packaging material of the present invention can take various forms depending on the contents, usage environment, and usage pattern. Bags can also be made into various shapes, such as self-standing packaging materials (standing pouches), tubes, and sachets (small bags). Heat-sealing can be performed using known methods such as bar seal, rotary roll seal, belt seal, impulse seal, high-frequency seal, and ultrasonic seal.

[0174] The packaging material of the present invention is filled with contents through its opening, and then the opening is heat-sealed to produce a product using the packaging material of the present invention. Examples of the contents to be filled include foods such as rice crackers, bean snacks, nuts, biscuits, cookies, wafer snacks, marshmallows, pies, semi-dried cakes, candies, and snacks; bread, snack noodles, instant noodles, dried noodles, pasta, aseptically packaged cooked rice, porridge, porridge, packaged rice cakes, and cereal foods; pickles, boiled beans, natto, miso, frozen tofu, tofu, nametake mushrooms, konjac, processed wild vegetables, jams, peanut cream, salads, frozen vegetables, and processed potato products; livestock products such as ham, bacon, sausages, processed chicken, and corned beef; and fish and meat products. Examples of processed seafood products include sausages, fish paste products, kamaboko, nori seaweed, tsukudani (simmered foods in soy sauce), bonito flakes, salted fish, smoked salmon, and spicy cod roe; fruit pulp such as peaches, mandarin oranges, pineapples, apples, pears, and cherries; vegetables such as corn, asparagus, mushrooms, onions, carrots, radishes, and potatoes; cooked foods such as frozen and chilled prepared dishes, including hamburgers, meatballs, fried seafood, gyoza, and croquettes; dairy products such as butter, margarine, cheese, cream, instant creamy powder, and infant formula; liquid seasonings, retort curry, and pet food.

[0175] In addition, the present invention can also be used as a packaging material for various non-food products, such as cigarettes, disposable body warmers, medicines such as infusion packs, liquid laundry detergent, liquid kitchen detergent, liquid bath detergent, liquid bath soap, liquid shampoo, liquid conditioner, cosmetics such as lotion and emulsion, vacuum insulation materials, batteries, etc.

[0176] In packaging materials using the multilayer film or laminate of the present invention, it is preferable to form any tear initiation portion such as a V notch, I notch, perforation, or micropore in the sealed portion in order to weaken the initial tear strength and improve openability. [Example]

[0177] Next, the present invention will be described in more detail with reference to examples and comparative examples.

[0178] <Preparation of fatty acid metal salts> (Preparation of bismuth stearate) 158.48 parts by mass of stearic acid and 37.36 parts by mass of bismuth oxide were reacted at 130°C, and 191.36 parts by mass of solid bismuth stearate was obtained after dehydration under reduced pressure at 130°C. The bismuth content in the obtained bismuth stearate was 17% by mass.

[0179] (Preparation of lanthanum stearate) To a mixed solution of 100 parts by mass of distilled water and 92.07 parts by mass of concentrated hydrochloric acid (purity 35%), 50 parts by mass of lanthanum oxide was added with stirring to obtain 246.07 parts by mass of a lanthanum chloride solution. Next, 862.30 parts by mass of distilled water, 100 parts by mass of stearic acid, and 72.46 parts by mass of 20% aqueous sodium hydroxide solution were reacted at 90°C, and 96.99 parts by mass of the lanthanum chloride solution prepared above was added and reacted at 90°C. After washing with water, the mixture was dehydrated under reduced pressure at 130°C, yielding 116.42 parts by mass of solid lanthanum stearate. The lanthanum content in the resulting lanthanum stearate was 14% by mass.

[0180] (Creation of neodymium stearate) To a mixed solution of 100 parts by mass of distilled water and 92.54 parts by mass of concentrated hydrochloric acid (purity 35%), 50 parts by mass of neodymium oxide was added with stirring to obtain 363.81 parts by mass of a neodymium chloride solution. Next, 862.30 parts by mass of distilled water, 100 parts by mass of stearic acid, and 72.46 parts by mass of 20% aqueous sodium hydroxide solution were reacted at 90°C, and 98.97 parts by mass of the neodymium chloride solution prepared above was added and reacted at 90°C. After washing with water, the mixture was dehydrated under reduced pressure at 150°C, yielding 117.06 parts by mass of solid neodymium stearate. The neodymium content in the resulting neodymium stearate was 15% by mass.

[0181] <Masterbatch production> Low-density polyethylene (density 0.919 g / cm 389 parts by mass of bismuth stearate (MFR 7.0 g / 10 min), 10 parts by mass of solid bismuth stearate, and 1 part by mass of porous silica were mixed and melt-kneaded in a φ30 mm twin-screw vented extruder (set temperature 160°C, mesh filter with a capture particle size of 40 μm). The resulting resin composition was pelletized to obtain a polyethylene masterbatch of bismuth stearate (hereinafter referred to as St-Bi-PEMB).

[0182] The following masterbatches were obtained in the same manner as above, except that the composition of the masterbatch was changed as shown in Table 1. St-Bi-PEMB: Bismuth stearate polyethylene masterbatch St-La-PEMB1: Lanthanum stearate polyethylene masterbatch (10% lanthanum stearate, 1% porous silica) St-Nd-PEMB: Neodymium stearate polyethylene masterbatch St-La-PEMB2: Lanthanum stearate polyethylene masterbatch (10% lanthanum stearate, 0.5% porous silica) St-La-PEMB3: Lanthanum stearate polyethylene masterbatch (10% lanthanum stearate, 0.75% porous silica) Porous material - PEMB1: Low-density polyethylene masterbatch containing 10% porous silica Porous-PEMB2: Low-density polyethylene masterbatch containing 15% porous silica

[0183] [Table 1]

[0184] Example 1 <Preparation of multilayer film> The outermost layer resin is linear low-density polyethylene (density 0.931 g / cm 3 100 parts by mass of LLDPE1 (MFR 3.6 g / 10 min) was used. 60 parts by mass of LLDPE1 and 100 parts by mass of high-density polyethylene (density 0.960 g / cm3 A resin mixture of 40 parts by mass of linear low-density polyethylene (density 0.919 g / cm 3 , MFR 7.5 g / 10 min) (hereinafter referred to as HDPE) was used as the resin for the sealing layer. 3 A mixture of 80 parts by mass of LLDPE2 (Molecular Weight 4.0 g / 10 min) and 20 parts by mass of St-Bi-PEMB was used. These resins were fed into an extruder (50 mm diameter) for the outermost layer, an extruder (50 mm diameter) for the intermediate layer, and an extruder (50 mm diameter) for the seal layer, respectively, and melted at 200-230°C. The molten resins were then fed into a T-die / chill roll coextrusion multilayer film manufacturing apparatus equipped with a feedblock (feedblock and T-die temperature: 250°C) and co-melt extrusion was carried out to obtain the multilayer film of Example 1, which had a three-layer structure of outermost layer / intermediate layer / seal layer, with layer thicknesses of 28 μm / 8.0 μm / 4.0 μm (total 40 μm). The concentration of the antibacterial agent in the seal layer was 2% by mass. Before winding the film, the surface of the outermost layer was subjected to a corona treatment.

[0185] (Examples 2 to 8, Comparative Examples 1 and 2) Multilayer films of Examples 2 to 8 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the construction of the multilayer film was changed as shown in Tables 2 and 3. Example 9 When the film of Example 8 was produced, it was wound up without subjecting the surface of the outermost layer to corona treatment, to give the multilayer film of Example 9.

[0186] <Antibacterial> The multilayer films produced in Examples 1 to 9 and Comparative Examples 1 and 2 were tested (n=1) for the test bacteria "Escherichia coli (NBRC3972)" and "Staphylococcus aureus (NBRC12732)" in accordance with JIS Z2801 "Antibacterial Products - Antibacterial Test Methods - Antibacterial Effect" to evaluate their antibacterial activity. The antibacterial activity value refers to the difference in the logarithmic value of the viable cell count after inoculation and culture of bacteria in an antibacterial product (the multilayer films of Examples 1 to 9) and an untreated product; a value of 1.0 or higher indicates a tendency for antibacterial activity, a value of 2.0 or higher indicates antibacterial activity, and a value of less than 1.0 indicates no antibacterial activity. The evaluation results are shown in Tables 1 and 2.

[0187] <Seal strength> The seal layer surfaces of the multilayer films produced in Examples 1 to 9 and Comparative Examples 1 and 2 were overlapped and heat-sealed at a temperature of 130°C and a pressure of 0.2 MPa for 1.0 second to obtain test specimens. The obtained samples were cut to a width of 15 mm, and the seal strength was measured using a tensile tester (manufactured by A&D Co., Ltd.) in a thermostatic chamber at 23°C and 50% RH. The measurement results are shown in Tables 1 and 2 as "Seal Strength (N)."

[0188] <Haze level> The haze (unit: %) of the multilayer films produced in Examples 1 to 9 and Comparative Examples 1 and 2 was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7105. In the present invention, 10% or less is preferred. The measurement results are shown in Tables 1 and 2 as "haze (%)."

[0189] [Table 2]

[0190] [Table 3]

[0191] The abbreviations in the table are as follows: LLDPE1: Linear low-density polyethylene (density 0.931 g / cm 3 , MFR3.6g / 10min) LLDPE2: Linear low-density polyethylene (density 0.919 g / cm 3 , MFR4.0g / 10min) HDPE: High-density polyethylene (density 0.960 g / cm 3 , MFR7.5g / 10min) LDPE: Low-density polyethylene (density 0.919 g / cm 3 , MFR7.0g / 10min)

[0192] As is clear from the above table, the multilayer films of the present invention in Examples 1 to 9 have a seal layer containing linear low-density polyethylene and / or low-density polyethylene and an antibacterial agent that is a metal salt of a fatty acid, and an intermediate layer containing high-density polyethylene, and were found to tend to exhibit antibacterial activity (although an antibacterial test was not conducted on Example 5, since only the total thickness differs from Examples 4 and 6, it is certain that it tends to have antibacterial activity similar to Examples 4 and 6). Furthermore, the multilayer films of the present invention in Examples 1 to 9, despite being multilayer films containing an antibacterial agent, had excellent transparency and exhibited seal strength equivalent to that of multilayer films not containing an antibacterial agent. On the other hand, the multilayer films of Comparative Examples 1 and 2, which did not contain a metal salt of a fatty acid, did not have an antibacterial effect.

Claims

1. A multilayer film comprising a seal layer and an intermediate layer, the sealing layer comprises linear low-density polyethylene and / or low-density polyethylene and an antibacterial agent; the intermediate layer comprises high density polyethylene; the antibacterial agent is a metal salt of a fatty acid; The metal of the metal salt of a fatty acid is at least one selected from lithium, sodium, potassium, rubidium, cesium, boron, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, tin, antimony, copper, silver, zinc, molybdenum, vanadium, strontium, zirconium, barium, bismuth, lead, gold, platinum, and rare earths. A multilayer film characterized by:

2. 2. The multilayer film according to claim 1, wherein the fatty acid has a melting point of 25°C or higher.

3. The fatty acid is at least one selected from the group consisting of stearic acid, palmitic acid, lauric acid, and myristic acid. The multilayer film of claim 1.

4. The multilayer film according to claim 1 , wherein the sealing layer further contains a porous material.

5. The multilayer film according to claim 1 , wherein the metal is at least one selected from the group consisting of bismuth, lanthanum, and neodymium.

6. The multilayer film according to claim 1, wherein the content of the antibacterial agent in the sealing layer is 0.5 to 15% by mass.

7. The multilayer film according to claim 1 , wherein 90% by mass or more of the resin constituting the multilayer film is a polyethylene-based resin.

8. A laminate comprising the multilayer film according to any one of claims 1 to 7.

9. A packaging material comprising the multilayer film according to any one of claims 1 to 7.

10. A packaging material comprising the laminate according to claim 8.

11. The packaging material according to claim 9, which is for packaging food.

12. The packaging material according to claim 10, which is for packaging food.

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