Rust-resistant film

Abstract

To provide a rust-prevention film which is excellent in production suitability, and can suppress occurrence of rust in contents during conveyance and long-term storage while having simple layer constitution, and a rust-prevention packaging material and a rust-prevention package produced using the rust-prevention film.SOLUTION: A rust-prevention film of a single layer or multiple layers contains at least a rust-prevention agent and a binder resin, in which the rust-prevention agent contains one or two or more kinds selected from the group consisting of a fatty acid, a metal fatty acid and a fatty acid ester.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rust-preventive film that suppresses the generation of rust on packaged contents, and a packaging material and a package produced using the rust-preventive film. The rust-preventive film according to the present invention can be applied to products in various fields, and is particularly suitable for use as a packaging material for metal products such as on-vehicle screws, shafts, metal plates, etc., and for accommodating electrical components and the like.

Background Art

[0002] Packaging materials for the purpose of transporting and long-term storing metal products composed of metal materials or parts using metal are being developed. There is a demand for a packaging material that has higher and more stable rust-preventive properties so as to maintain the functions and properties of the metal products as the contents, and can be manufactured by a simple manufacturing process with a simple layer structure. For the purpose of preventing rust on metal product contents, packaging laminates in which a resin contains a highly vaporizable rust-preventive agent that volatilizes at normal temperature to exhibit a rust-preventive effect are described in Patent Documents 1 to 3. However, there are concerns about effects other than the rust-preventive effect, such as the need for sealing by an exterior, or when the vaporized rust-preventive agent adheres to the contents, the contents may deteriorate or a functional failure may occur, and it is troublesome to remove the adhered rust-preventive agent, so the use is limited, and a rust-preventive film that does not use a volatile rust-preventive agent is desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention aims to solve the above problems and provide a rust-preventive film that is easy to manufacture, has a simple layer structure, and can suppress the occurrence of rust on the contents during transportation and long-term storage, as well as a rust-preventive packaging material and rust-preventive packaging made using the rust-preventive film. [Means for solving the problem]

[0005] As a result of various studies, the present inventors have found that a rust-preventive film containing at least the rust inhibitor defined in the present invention and a binder resin achieves the above objective. In other words, the present invention is characterized by the following: 1. A single-layer rust-preventive film containing at least a rust inhibitor and a binder resin, The rust inhibitor is characterized by containing at least one or more selected from the group consisting of fatty acids, metal fatty acids, and fatty acid esters, in the form of a rust-preventive film. 2. A multilayer rust-preventive film having at least a rust-preventive layer, The rust-preventive layer contains a rust inhibitor and a binder resin. The rust inhibitor contains at least one or more selected from the group consisting of fatty acids, metal fatty acids, and fatty acid esters. A rust-preventive film characterized in that a layer containing a thermoplastic resin is laminated on one or both sides of the rust-preventive layer. 3. The rust-preventive film according to item 2 above, characterized in that the rust-preventive film is a co-extruded film. 4. The rust-preventive film according to 2 or 3 above, wherein the rust-preventive film further comprises an intermediate layer. 5. A rust-preventive film according to any one of 1 to 4 above, characterized in that the number of carbon atoms in the fatty acid portion of the fatty acid, metal fatty acid, or fatty acid ester is 6 or more and 20 or less. 6. The rust-preventive film according to any one of 1 to 5 above, characterized in that the rust inhibitor further contains an antioxidant and an alkaline agent that exhibits alkalinity and neutralizes acidic substances. 7. The rust-preventive film according to 6 above, characterized in that the antioxidant contains a phenolic antioxidant and / or a phosphorus-based antioxidant. 8. The rust-preventive film according to 6 or 7 above, characterized in that the alkaline agent contains one or more selected from the group consisting of alkali metal compounds, alkaline earth metal compounds, and aluminum compounds. 9. A rust-preventive packaging material characterized by comprising a rust-preventive film as described in any of items 1 to 8 above. 10. A rust-preventive packaging body characterized by being made of the rust-preventive packaging material described in item 9 above. [Effects of the Invention]

[0006] The present invention provides a rust-preventive film and rust-preventive packaging materials and rust-preventive packaging bodies made using the rust-preventive film, which solve the above-mentioned problems, have excellent manufacturing suitability, and, despite having a simple layer structure, can suppress the occurrence of rust on the contents during transportation and long-term storage. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view showing an example of the layer structure of the rust-preventive film of the present invention. [Figure 2] This is a schematic cross-sectional view showing an example of another embodiment of the layer structure of the rust-preventive film of the present invention.

[0008] In each diagram, the size and proportions of components may be altered or exaggerated for clarity. Additionally, unnecessary or repetitive symbols may be omitted for ease of understanding. Although not shown in the diagrams, adhesive layers can also be placed between each layer. Furthermore, if necessary, to strengthen the adhesive strength (bonding strength) between each layer, physical surface treatments such as corona discharge treatment, ozone treatment, plasma treatment, glow discharge treatment, and sandblasting, or chemical surface treatments such as oxidation treatment using chemicals, can be applied to the laminated surface of each layer in advance. [Modes for carrying out the invention]

[0009] The rust-preventive film, rust-preventive packaging material, and rust-preventive packaging of the present invention will be described in more detail below. Specific examples will be provided, but the present invention is not limited thereto. In this invention, the terms "film" and "sheet" are treated as synonymous.

[0010] Rust-resistant film The rust-preventive film of the present invention is a resin film that contains at least a rust inhibitor and a binder resin, and has heat-sealing properties. Furthermore, the rust-preventive film of the present invention may be a single-layer film or a multi-layer film. The rust inhibitor used in the rust-preventive film of the present invention preferably contains two or more substances selected from the group consisting of fatty acids, metallic fatty acids, and fatty acid esters. Furthermore, it is preferable that it contains two or more substances selected from the group consisting of "alkaline agents for neutralizing acidic substances by exhibiting alkalinity," "antioxidants," and "acidic gas adsorbents for adsorbing acidic gases." By using two or more rust inhibitors in combination, an efficient rust-preventive effect can be achieved. Hereinafter, fatty acids, metallic fatty acids, and fatty acid esters will be collectively referred to as fatty acids. To suppress rust formation, it is effective to adsorb acidic gases entering from the outside or present in the internal space of the packaging onto a rust-preventive film, or to apply or coat a rust inhibitor to the surface of the contents to provide water repellency, prevent oxidation of the contents' surface, and neutralize acidic gases that come into contact with the contents' surface. By using the above-mentioned rust inhibitors in combination, these methods can be used to efficiently achieve rust prevention.

[0011] The thickness of the rust-preventive film is not particularly limited, but is preferably 25 μm or more and 200 μm or less. If it is thinner than the above range, the rigidity is too low, it is likely to break, and it is difficult to exhibit a sufficient balance of supportability, rust-preventive effect, and heat-sealability. If it is thicker than the above range, the rigidity is too strong, and the usability as a packaging material is likely to deteriorate.

[0012] The rust-preventive film can have high transparency according to the application. The total light transmittance of the rust-preventive film with high transparency is preferably 50% or more. The transparency of the rust-preventive packaging material made of the rust-preventive film with high transparency is also high. The rust-preventive package made of the rust-preventive packaging material with high transparency can easily visually recognize the contents, the label attached to the contents, the characters and seals engraved on the contents, etc.

[0013] The rust-preventive film can contain various plastic compounding agents and additives, etc., for the purpose of improving and modifying, for example, processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, releasability, flame retardancy, antifungal properties, electrical properties, strength, etc. The content can be arbitrarily contained from an extremely small amount to several tens of %, depending on the purpose. In the above, as general additives, for example, an antiblocking agent, a lubricant, a crosslinking agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a reinforcing agent, an antistatic agent, a pigment, a resin for modification, etc. can be contained.

[0014] In the case of a single-layer rust-preventive film, the rust-preventive film of the present invention contains at least a rust-preventive agent and a binder resin in one layer. When the binder resin has heat-sealability, the surface of one side or both sides of the single-layer rust-preventive film can have heat-sealability. The rust inhibitor may be uniformly dispersed in a single layer, or it may be dispersed with a concentration gradient. For example, if a concentration gradient is provided such that there is a large amount of rust inhibitor near the surface of one side and a small amount near the surface of the other side, the surface on the side with the large amount of rust inhibitor will exhibit rust prevention more efficiently, while the surface on the side with the small amount of rust inhibitor will have higher heat sealability. By lowering the overall concentration of the rust inhibitor or increasing the concentration in the center of the layer, the heat-sealability of both sides of the rust-preventive film can also be improved. The rust inhibitor content in the rust-preventive film is preferably 0.1% by mass or more and 50% by mass or less. If it is below this range, it is difficult to achieve sufficient rust prevention, and if it is above this range, film-forming properties and heat-sealing properties tend to be poor.

[0015] In the case of a multilayer rust-preventive film, the rust-preventive film of the present invention has at least a rust-preventive layer containing a rust inhibitor and a binder resin. The binder resin is a thermoplastic resin, and if the binder resin has heat-sealing properties, then one or both sides of the anti-corrosion layer may also have heat-sealing properties. Furthermore, it is preferable that a layer containing a thermoplastic resin is laminated on one or both sides of the rust-preventive layer. A multilayer anti-corrosion film may have, for example, intermediate and outer layers that perform various functions depending on the application. In this case, it is preferable that the anti-corrosion film is laminated in the order of anti-corrosion layer, intermediate layer, and outer layer. Furthermore, the layers may be laminated with an adhesive layer in between. Rust-preventive films suppress rust formation in their contents by having a rust-preventive layer. For example, if the thermoplastic resin contained in the outer layer is a heat-sealable resin, the multilayer anti-corrosion film can have heat-sealing properties. The rust inhibitor may be uniformly dispersed in the rust-preventive layer, or it may be dispersed with a concentration gradient. For example, if a concentration gradient is provided such that there is a large amount of rust inhibitor near the surface of one side and a small amount near the surface of the other side, the surface on the side with the large amount of rust inhibitor will exhibit rust prevention more efficiently, while the surface on the side with the small amount of rust inhibitor will have higher heat-sealing properties. By lowering the overall concentration of the rust inhibitor or increasing the concentration of the rust inhibitor in the central part of the rust-preventive layer, the adhesion between the two interfaces of the rust-preventive layer can be improved. The rust inhibitor content in the rust-preventive layer is preferably 0.1% by mass or more and 50% by mass or less. If it is below this range, it is difficult to achieve sufficient rust prevention, and if it is above this range, film-forming properties and heat-sealing properties tend to be poor.

[0016] In multilayer anti-corrosion films, it is preferable that one or both surfaces have an anti-corrosion layer. Having an anti-corrosion layer on the surface makes it easier for the anti-corrosion properties to adhere to or coat the surface of the contents. Furthermore, when we say that the surface is a rust-preventive layer, it means that all or part of the rust-preventive layer is exposed on the surface.

[0017] <Rust Inhibitor> The rust inhibitor is a compound that suppresses the occurrence of rust on the contents packaged by the rust-preventive film of the present invention. The rust inhibitor in this invention can suppress rust formation by remaining inside the rust-preventive film of the present invention and adsorbing acidic gases, or by adhering from the rust-preventive film of the present invention to the surface of the packaged contents by vaporization, scattering, or contact transfer, thereby neutralizing acidic substances on the surface of the contents, repelling water to suppress the adhesion of moisture, and suppressing oxidation.

[0018] In the present invention, it is preferable that the rust inhibitor contains two or more selected from the group consisting of "an alkaline agent that exhibits alkalinity and neutralizes acidic substances," "an antioxidant," "one or more selected from the group consisting of fatty acids, metal fatty acids, and fatty acid esters," and "an acid gas adsorbent for adsorbing acidic gases." When two or more types are used in combination, different effects such as acid gas adsorption, neutralization of acidic substances, water repellency, and oxidation inhibition contribute synergistically, resulting in a synergistic improvement in rust prevention. Preferred combinations of rust inhibitors include, for example, antioxidants and alkaline agents, antioxidants and fatty acids, antioxidants, alkaline agents and fatty acids, alkaline agents and fatty acids, alkaline agents and acidic gas adsorbents, and fatty acids and acidic gas adsorbents.

[0019] Details of each type of rust inhibitor contained in the rust-preventive film of the present invention are as follows.

[0020] [Alkaline agent] The alkaline agent in this invention is a compound that exhibits alkalinity itself, and by adhering to the surface of the packaged contents, it can neutralize acidic substances that cause rust formation and suppress the occurrence of rust. Examples of alkaline agents include alkali metal compounds, alkaline earth metal compounds, and aluminum compounds. In this invention, alkali metals refer to alkali metals in a broad sense, specifically the Group 1 metallic elements Li, Na, K, Rb, Cs, and Fr, with Li, Na, and K being preferred among these. Furthermore, alkaline earth metals, in a broad sense, refer to the metallic elements of Group 2: Be, Mg, Ca, SrBa, and Ra.

[0021] Examples of alkali metal compounds include alkali metal oxides, alkali metal chlorides, alkali metal hydroxides, etc. Specific examples of alkali metal compounds include Li2O, Na2O, K2O, LiCl, and LiOH. Among these, Na2O and K2O are preferred.

[0022] Examples of alkaline earth metal compounds include alkaline earth metal oxides, alkaline earth metal chlorides, alkaline earth metal hydroxides, etc. Specific examples of alkaline earth metal compounds include BeO, MgO, CaO, SrO, BaO, RaO, MgCl2, CaCl2, Mg(OH)2, Ca(OH)2, etc. Among these, MgO, CaO, Mg(OH)2, Ca(OH)2, etc. are preferred.

[0023] Specific aluminum compounds include Al2O3 and Al(OH)3. Among these, Al2O3 is preferred.

[0024] Among the specific alkaline agents mentioned above, it is preferable to use one or more selected from the group consisting of MgO, CaO, Mg(OH)2, Ca(OH)2, and Al2O3.

[0025] The alkaline agent is used in powder form, and the average particle size based on the number of particles is preferably between 0.1 μm and 20 μm. If the average particle size is smaller than the above range, the alkaline agent is more likely to aggregate, and if it is larger than the above range, the surface area will be smaller, which may result in poor rust prevention. The alkaline agent content in the rust-preventive layer of a single-layer or multi-layer rust-preventive film is preferably 15% by mass or more and 50% by mass or less. If it is below this range, sufficient rust prevention effect is difficult to achieve, and if it is above this range, film-forming properties and heat-sealing properties tend to be poor.

[0026] [Antioxidant] The antioxidant in this invention adheres to the surface of the packaged contents and can suppress the occurrence of rust due to oxidation of the contents' surface. As antioxidants, publicly known and commonly used antioxidants for packaging materials can be used, but phenolic antioxidants and phosphorus-based antioxidants are preferred, and among these, those having both hydrophilic and hydrophobic groups are more preferred.

[0027] A preferred phenolic antioxidant is pentaerythritol tetrakis[3-(3,5-ditter-butyl-4-hydroxyphenyl)propionate]. Preferred phosphorus-based antioxidants include tris(2,4-ditterbutylphenyl)phosphite and 2,4,8,10-tetratertitterbutyl-6-(3-(3-methyl-4-hydroxy-5-tertitterbutylphenyl)propoxy)dibenzo(d,f)(1,3,2)dioxaphosphine.

[0028] The antioxidant content in a single-layer or multi-layer rust-preventive film is preferably 0.1% by mass or more and 15% by mass or less. If it is below this range, it is difficult to achieve sufficient rust prevention, and if it is above this range, the rust prevention effect does not improve significantly, and film-forming properties and heat sealability tend to be poor, which is undesirable.

[0029] [Fatty acids] The fatty acids in this invention adhere to the surface of the packaged contents, exhibiting a water-repellent effect, thereby suppressing the adhesion of moisture that causes rust to the surface of the contents, and thus inhibiting the occurrence of rust. Specific examples of fatty acids include fatty acids, metallic fatty acids, and fatty acid esters. It is believed that fatty acids exhibit water repellency because the aliphatic chain portion functions as a hydrophobic group, the carboxylic acid portion functions as a hydrophilic group, and the hydrophilic group adheres to the surface of the contents while the hydrophobic portion adheres facing outwards. The composition of the fatty acids is preferably such that the number of carbon atoms in the fatty acid portion is between 6 and 20. If the number of carbon atoms is less than the above range, the boiling point may be too close to the film formation temperature, which may cause bubbles to form or prevent film formation. If the number of carbon atoms is more than the above range, vaporization, scattering, and adhesion by contact transfer from the rust-preventive film to the surface of the packaged contents may become difficult. Specific examples of fatty acids include caproic acid, heptanoic acid, nonanoic acid, octanoic acid, decanoic acid, undecylic acid, lauric acid, stearic acid, nonadecylic acid, and arachidic acid.

[0030] Specific examples of metallic fatty acids include alkali metal salts and alkaline earth metal salts of the above-mentioned fatty acids, with Ca salts being preferred. Specific examples of fatty acid esters include alcohol esters of the above-mentioned fatty acids and glycerin fatty acid esters. Glycerin fatty acid esters are preferably glycerin tri fatty acid esters, preferably glycerin fatty acid esters, and more preferably glycerin tricaprylic acid esters. Among the above fatty acids, it is preferable to use one or more selected from the group consisting of heptanoic acid, octanoic acid, decanoic acid, lauric acid, stearic acid, caprylic acid, capric acid, calcium stearate, and glycerol tricaprylate. The content of fatty acids in the rust-preventive layer of a single-layer or multi-layer rust-preventive film is preferably 0.1% by mass or more and 30% by mass or less. If it is below the above range, it is difficult to achieve sufficient rust prevention effect, and if it is above the above range, the rust prevention effect does not improve much, and the film-forming properties and heat sealability tend to be poor, so it is undesirable.

[0031] [Acid gas adsorbent] The acidic gas adsorbent in this invention is SO x NO x By adsorbing acidic gases such as carbon dioxide, it is possible to suppress rust formation on the surface of the packaged contents due to these acidic gases. By containing an acidic gas adsorbent, the rust-preventive film can suppress the intrusion of these acidic gases from outside the packaging through the rust-preventive film, or it can adsorb these acidic gases present in the contents storage area inside the packaging, thereby reducing their concentration. The acidic gas adsorbent preferably contains one or more selected from the group consisting of hydrophobic zeolites, metal-supported zeolites, and amino group-supported porous materials. The acidic gas adsorbent may have any external shape, such as spherical, rod-shaped, or elliptical, and may be in any form, such as powder, lump, or granules. However, from the viewpoint of uniform dispersibility, kneading characteristics, and film-forming properties when dispersed in resin, a powder form is preferred.

[0032] Acidic gas adsorbents are used in powder form, and the average particle size based on the number of particles is preferably 0.1 μm or more and 20 μm or less. Here, the average particle size is the value measured by dynamic light scattering. If the average particle size is smaller than the above range, the acidic gas adsorbent is more likely to aggregate, and if it is larger than the above range, the surface area will be smaller, which may result in poor rust prevention. The content of the acidic gas adsorbent contained in the rust-preventive layer of a single-layer or multi-layer rust-preventive film is preferably 0.1% by mass or more and 30% by mass or less. If it is below the above range, it is difficult to achieve sufficient rust prevention effect, and if it is above the above range, the rust prevention effect does not improve much, and the film-forming properties and heat sealability tend to be poor, so it is undesirable.

[0033] (Hydrophobic zeolite) Hydrophobic zeolites are porous materials, and the higher the molar ratio of their constituent components, SiO2 / Al2O3, the higher their hydrophobicity. Hydrophobic zeolites with a SiO2 / Al2O3 molar ratio of 30 / 1 to 10000 / 1 are preferred. Due to its high hydrophobicity, it has a high ability to adsorb low-polarity acidic gases without adsorbing highly polar water vapor. In this invention, hydrophilic zeolites with a molar ratio within the above range are preferably used, considering the balance between moisture absorption performance and availability.

[0034] (Metal-supported zeolite) Metal-supported zeolites are zeolites on which a metal other than Si or Al is supported. The supported metal is thought to be actually supported on the zeolite in the form of a metal oxide or in the form of metal atoms themselves. In this invention, the term "metal-supported zeolite" is used as a general term for both metal oxide-supported zeolites and metal atom-supported zeolites. When rust-generating gaseous components come into contact with metal-supported zeolite, these gaseous components are thought to undergo one of the following reactions: ionization, bonding, decomposition, oxidation, reduction, etc., thereby losing their ability to generate rust. The supported metal species is preferably one that does not react easily with moisture and has a lower ionization tendency than iron. Specifically, one or more species selected from the group consisting of copper, zinc, silver, platinum, etc., is preferred, and one or more species selected from the group consisting of copper, zinc, and silver is more preferred. Furthermore, the supported zeolite can be either hydrophilic or hydrophobic.

[0035] (Amino group supported porous material) An amino group-supported porous material is a porous material on which a chemical adsorbent containing amino groups is supported. As for the loading method, known or conventional loading methods can be applied. For example, the material can be loaded by impregnating a porous body with a solution containing a chemical adsorbent and then drying it. Amino group-supported porous materials selectively react with and adsorb aldehyde compounds and the like at the amino group portion, and also exhibit physical adsorption properties at the pores of the porous material. Any compound having numerous pores on its surface can be used as the porous material on which the amino group is supported. Inorganic porous materials are preferred, and examples include zeolites, silicon dioxide, silicates, activated carbon, titania, inorganic phosphates such as calcium phosphate, alumina, aluminum hydroxide, magnesium hydroxide, and mixtures thereof. In particular, it is preferable to use aluminum hydroxide, zeolite, or silicate, as these have a porous state with an effective pore size relative to the molecular size and cluster size of the adsorbed substance, and also from a safety standpoint.

[0036] [Method for dispersing rust inhibitors] The rust inhibitor is preferably incorporated via a masterbatch obtained by melt-blending the rust inhibitor with a thermoplastic resin. Specifically, it is preferable to prepare a masterbatch by melt-blending a rust inhibitor with a thermoplastic resin at a relatively high concentration, and then dry-blending the masterbatch with components such as a binder resin to achieve the desired rust inhibitor concentration. Each of the rust inhibitors and thermoplastic resins that are melt-blended may be of one type or two or more types, and one or more rust inhibitors may be contained in a single masterbatch. The content of the rust inhibitor in the masterbatch is preferably 3% by mass or more and 95% by mass or less, more preferably 20% by mass or more and 90% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less. Within the above range, it is easy to include a necessary and sufficient amount of rust inhibitor in a dispersed state. The thermoplastic resin mentioned above may be the same as, or different from, the binder resin contained in the anti-corrosion layer.

[0037] <Binder resin> The binder resin contained in the layer containing the rust inhibitor is preferably a resin that has affinity suitable for dispersing the rust inhibitor and has excellent film-forming properties, and more preferably a resin that has heat-sealing properties.

[0038] Preferred binder resins include polyolefin resins, polyester resins, polyamide resins, polyaramid resins, polycarbonate resins, polyacetal resins, fluoropolymer resins, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers (EVOH), polyvinyl alcohol, polyacrylonitrile, and others. These resins may be used individually or in mixtures of two or more. Among these resins, polyolefin resins are preferred from the viewpoint of film-forming properties.

[0039] Specific examples of polyolefin resins include polyethylene resins, polypropylene resins, unsaturated carboxylic acid-modified resins of polyolefin resins, cyclic polyolefin resins, and cyclic olefin copolymers. It is preferable to use acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc., as the unsaturated carboxylic acid. These polyolefin resins may be used individually or in mixtures of two or more, or in multilayer structures containing different types of resins. The copolymerized unsaturated carboxylic acids may be used individually or in mixtures of two or more. Among these polyolefin resins, polyethylene resins are preferred from the viewpoint of film-forming properties.

[0040] Specific examples of polyethylene resins include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), metallocene polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate ethyl copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, and unsaturated carboxylic acid modified resins of polyethylene polyolefin resins. It is preferable to use acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc., as the unsaturated carboxylic acid. Among the polyethylene resins mentioned above, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) are more preferred, and linear low-density polyethylene (LLDPE) is even more preferred. These polyethylene resins may be used individually or as a mixture of two or more.

[0041] <Rust-preventive layer> The rust-preventive layer is a layer in a multi-layer rust-preventive film that contains a rust inhibitor and a binder resin. The binder resin contained in the rust-preventive layer is made of a thermoplastic resin and may or may not have heat-sealing properties. If it has heat-sealing properties, it is preferable to include a heat-sealing resin, or the binder resin may contain a heat-sealing resin. The rust-preventive layer may be a single layer containing two or more rust inhibitors, or it may consist of two or more layers containing rust inhibitors of different types or concentrations. The rust-preventive layer is preferably laminated on the surface of a multi-layered rust-preventive film. By being laminated on the surface, it can easily exhibit rust-preventive properties.

[0042] The rust inhibitor content in the rust-preventive layer is preferably 0.1% by mass or more and 50% by mass or less. If it is below this range, sufficient rust prevention effect is difficult to achieve, and if it is above this range, film-forming properties and heat sealability tend to be poor. The thickness of the rust-preventive layer can be appropriately set by those skilled in the art, but is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferably 10 μm or more and 50 μm or less. If it is thinner than the above range, it may not exhibit sufficient rust prevention, and if it is thicker than the above range, the rust prevention effect will not improve much, and the overall rigidity of the rust-preventive film may become too strong, making it difficult to use.

[0043] <Middle class> The intermediate layer can have various layers that impart mechanical, physical, and chemical functions to the rust-preventive film, such as support, rigidity, flexibility, and pinhole resistance. For example, by having a water vapor barrier layer, it is possible to suppress the intrusion of moisture into the contents storage area within the packaging, or to absorb moisture from the contents storage area to lower humidity, thereby suppressing condensation and providing excellent rust prevention to the contents. Specific examples of water vapor barrier layers include inorganic vapor deposition layers and metal foil layers.

[0044] For example, examples of resins used to enhance support include tough thermoplastic resins such as polyolefin resins, polyester resins, polyamide resins, polyaramid resins, polycarbonate resins, polyacetal resins, fluororesins, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers (EVOH), polyvinyl alcohol, polyacrylonitrile, and others. These resins may be used individually or in combination of two or more, or in multilayer structures containing different types of resins. Among these resins, polyolefin resins are preferred from the viewpoint of film-forming properties.

[0045] Specific examples of polyolefin resins include polyethylene resins, polypropylene resins, unsaturated carboxylic acid-modified resins of polyolefin resins, cyclic polyolefin resins, and cyclic olefin copolymers. It is preferable to use acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc., as the unsaturated carboxylic acid. These polyolefin resins may be used individually or in mixtures of two or more, or in multilayer structures containing different types of resins. The copolymerized unsaturated carboxylic acids may be used individually or in mixtures of two or more. Among these polyolefin resins, polyethylene resins are preferred from the viewpoint of film-forming properties.

[0046] Specific examples of polyethylene resins include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), metallocene polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate ethyl copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, and unsaturated carboxylic acid modified resins of polyethylene polyolefin resins. It is preferable to use acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc., as the unsaturated carboxylic acid. Among the polyethylene resins mentioned above, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) are more preferred, and linear low-density polyethylene (LLDPE) is even more preferred. These polyethylene resins may be used individually or as a mixture of two or more.

[0047] The thickness of the intermediate layer can be appropriately set by those skilled in the art, but if the purpose is to impart appropriate strength and rigidity to the laminate, a thickness of 5 μm or more and 100 μm or less is preferred, and a thickness of 10 μm or more and 50 μm or less is more preferred.

[0048] <Outer layer> The outer layer is a layer containing thermoplastic resin. The thermoplastic resin used in the outer layer can be of various types, as long as it does not significantly negatively affect the heat sealability or film-forming properties of the entire film. Specific examples of the thermoplastic resin include, for example, general-purpose polyethylene, polypropylene, methylpentene polymer, acid-modified polyolefin resins and other polyolefin resins, and mixtures of these resins. However, the resin is not limited to these, and a type of thermoplastic resin can be selected according to the purpose. The outer layer is preferably laminated on the surface of a multi-layered anti-corrosion film. There are no particular restrictions on the thickness of the outer layer, but a thickness of 10 μm or more and 100 μm or less is preferred. Within this range, there is little risk of significantly adverse effects on the heat sealability and film-forming properties of the entire film.

[0049] (Heat-sealable resin) The heat-sealable resin that can be used in the rust-preventive film of the present invention is not particularly limited, and any known heat-sealable resin can be used as long as it can be melted and fused by heat. Specific examples of heat-sealable resins include polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, metallocene polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylate ethyl copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, polyolefin resins such as polyethylene or polypropylene modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc., ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid ternary copolymer resin, cyclic polyolefin resin, cyclic olefin copolymer, polyethylene terephthalate (PET), and polyacrylonitrile (PAN). Among these, polyolefin resins are preferred, polyethylene resins are more preferred among polyolefin resins, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) are even more preferred among polyethylene resins, and linear low-density polyethylene (LLDPE) is particularly preferred.

[0050] <Adhesive layer> There are no particular restrictions on the adhesive used in the adhesive layer; adhesives for DL ​​(dry lamination), adhesives for EC (extrusion coating), adhesives for non-solvent lamination, any anchor coating agent, etc., can be used. Furthermore, the adhesive may be thermosetting, ultraviolet curing, electron beam curing, etc., and may be in any form such as aqueous, solution, emulsion, or dispersion. Its properties may also be in any form such as film / sheet, powder, or solid. Moreover, the bonding mechanism may be any form such as chemical reaction, solvent evaporation, thermal melting, or hot pressure.

[0051] Components that form such adhesive layers include polyvinyl acetate adhesives such as polyvinyl acetate and vinyl acetate-ethylene copolymers, polyacrylic acid adhesives consisting of copolymers of polyacrylic acid and polystyrene, polyester, polyvinyl acetate, etc., cyanoacrylate adhesives, ethylene copolymer adhesives consisting of copolymers of ethylene and monomers such as vinyl acetate, ethyl acrylate, acrylic acid, and methacrylic acid, cellulose adhesives, polyurethane adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, polyolefin adhesives such as LDPE, amino resin adhesives consisting of urea resin or melamine resin, phenolic resin adhesives, epoxy adhesives, reactive (meth)acrylic adhesives, elastomer adhesives consisting of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc., silicone adhesives, and inorganic adhesives consisting of alkali metal silicates, low-melting-point glass, etc.

[0052] <Method for manufacturing rust-preventive film> A method for manufacturing the rust-preventive film of the present invention will be described below. The manufacturing method shown below is just one example and does not limit the present invention. The anti-corrosion film can be manufactured using any method, such as T-die extrusion, extrusion inflation, or other methods. If the anti-corrosion film has a multilayer structure, each layer can be laminated using any method used when manufacturing ordinary packaging materials, such as wet lamination, dry lamination, solvent-free dry lamination, extrusion lamination, co-extrusion lamination, T-die co-extrusion, co-extrusion inflation, and others. Among the multilayer anti-corrosion films mentioned above, it is preferable that the film is a co-extruded film produced by a method including co-extrusion. Furthermore, when performing the above lamination, if necessary, pretreatments such as corona treatment or ozone treatment can be applied to the surface of each layer. In addition, anchor coating agents such as isocyanate-based (urethane-based), polyethyleneimine-based, polybutadiene-based, and organotitanium-based materials, or laminating adhesives such as polyurethane-based, polyacrylic-based, polyester-based, epoxy-based, polyvinyl acetate-based, cellulose-based, and others can be used as desired.

[0053] For example, let's explain the case of producing a corrosion-resistant film using the inflation method. If the rust-preventive film is a single layer, first, a resin composition for forming the rust-preventive film is prepared, and then the rust-preventive film is manufactured by inflation deposition. If the anti-corrosion film is multilayered, first, resin compositions for forming the anti-corrosion layer, intermediate layer, and outer layer are prepared. Then, the anti-corrosion layer, intermediate layer, and outer layer are co-extruded and laminated by inflation deposition to produce a multilayer anti-corrosion film. Furthermore, aging treatment may be performed as needed. In this way, laminates or packaging materials for liquid contents can be manufactured. The resulting anti-corrosion film may then be stretched uniaxially or biaxially, as needed.

[0054] Rust-preventive films can be subjected to secondary processing for the purpose of imparting chemical, electrical, magnetic, mechanical, friction / abrasion / lubrication, optical, thermal, biocompatibility, and other surface functions. Examples of secondary processing include embossing, painting, bonding, printing, metallizing (plating, etc.), machining, and surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.). Furthermore, the rust-preventive film can also be subjected to lamination (dry lamination or extrusion lamination), bag making, and other post-processing.

[0055] Rust-resistant packaging materials The rust-preventive packaging material of the present invention is a packaging material made from the rust-preventive film of the present invention, and may further include layers having various functions as needed. Rust-resistant packaging materials have rust-resistant properties similar to rust-resistant films and can be used, for example, as stretch films.

[0056] Rust-resistant packaging The rust-preventive packaging of the present invention is a packaging made from the rust-preventive packaging material of the present invention. There are no particular limitations on the shape or form of the rust-preventive packaging of the present invention. The rust-preventive packaging material can be folded, layered to enclose the contents, or heat-sealed to create various shapes and forms, and added value can be provided through printing and decoration. For example, a pouch-shaped rust-preventive packaging can be manufactured with less rust-preventive packaging material compared to a bottle-shaped rust-preventive packaging, making it effective for resource conservation.

[0057] For example, a pouch-shaped rust-preventive packaging can be made by folding the rust-preventive packaging material in half, or by preparing two sheets of rust-preventive packaging material, overlapping them with their heat-sealable layers facing each other, and then heat-sealing the surrounding edges using various heat-sealing methods such as side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, gusset seal type (pillow seal type), pleated seal type, flat-bottom seal type, square-bottom seal type, or gusset type. In the above, the heat sealing method can be a known method such as a bar seal, rotary roll seal, belt seal, impulse seal, high-frequency seal, or ultrasonic seal.

[0058] In rust-preventive packaging, it is preferable that the rust-preventive layer of the rust-preventive packaging material is located on the inside of the rust-preventive packaging, and the outer layer is located on the inside. This type of packaging allows the rust-preventive packaging to efficiently suppress the penetration of acidic gases from the outside and to adhere rust inhibitors to the surface of the contents, thereby preventing rust from forming on the contents. When preparing rust-preventive packaging, the packaging may be sealed while sucking out the air inside, or while replacing the contents space with air with a low oxygen content and low humidity. [Examples]

[0059] The present invention will be described in more detail by the following examples and comparative examples, but the present invention is not limited to these examples. Details of the raw materials used in the examples are as follows.

[0060] [Fatty acids] • Fatty acid 1: Heptanoic acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • Fatty acid 2: Stearic acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • Fatty acid 3: Decanoic acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • Fatty acid 4: Lauric acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • Fatty acid 5: Stearic acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • Metallic fatty acid 1: Calcium stearate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • Fatty acid ester 1: Triglyceride, Actor M2, manufactured by Riken Vitamin Co., Ltd.

[0061] [Antioxidant] Antioxidant 1: Phenolic antioxidant A060, manufactured by Adeka Co., Ltd. Antioxidant 2: Phosphorus-based antioxidant 2112 manufactured by Adeka Co., Ltd. Antioxidant 3: A phenol + phosphorus-based mixed antioxidant, A-612RG, manufactured by Adeka Co., Ltd.

[0062] [Alkaline agent] Alkaline agent 1: Calcium oxide, HAL-J, manufactured by Yoshizawa Lime Industry Co., Ltd. Average particle size: 1-2 μm.

[0063] [Binder resin, thermoplastic resin] • LLDPE1: LLDPE manufactured by Prime Polymer Co., Ltd., Evolu SP2020. Density 0.916 g / cm³ 3 MFR = 2.0g / 10 minutes. • LDPE1: LDPE manufactured by Nippon Polyethylene Co., Ltd., Novatec LC520. Density 0.923 g / cm³ 3 MFR 3.6g / 10 minutes.

[0064] <Preparing the Masterbatch> The masterbatch was prepared as follows. [Preparing Masterbatch 1] LDPE1 and fatty acid 1 were melt-blended in the following proportions to obtain masterbatch 1 (MB1). LDPE1 95 parts by mass Fatty acid 1 5 parts by mass

[0065] [Adjustments to Master Batch 2-11] According to the formulations in Table 1, the mixtures were melt-blended in the same manner as for Masterbatch 1 to obtain Masterbatches 2-11 (MB2-11).

[0066] [Table 1]

[0067] <Examples> We prepared rust-preventive films containing rust inhibitors and conducted various evaluations.

[0068] [Example 1] MB1 and LLDPE1 were dry-blended in the following proportions to obtain a rust-preventive layer resin composition. MB1 20 parts by mass LLDPE1 80 parts by mass The rust-preventive resin composition obtained above was fabricated at 160°C by inflation deposition to obtain a rust-preventive film (30 μm thick) consisting solely of the rust-preventive layer. Various evaluations were then performed.

[0069] [Example 2] A rust-preventive layer resin composition was obtained by dry blending MB1, MB8, MB11, and LLDPE1 in the following proportions. MB1 10 parts by mass MB8 10 parts by mass MB11 40 parts by mass LLDPE1 40 parts by mass Using the rust-preventive resin composition obtained above, a rust-preventive film (30 μm thick) consisting solely of a rust-preventive layer was obtained by the same procedure as in Example 1. Then, various evaluations were performed in the same manner as in Example 1.

[0070] [Example 3] MB1 and LLDPE1 were dry-blended in the following proportions to obtain a rust-preventive layer resin composition. MB1 20 parts by mass LLDPE1 80 parts by mass The rust-preventive resin composition obtained above and LLDPE1 were formed and laminated by inflation deposition at 160°C to obtain a rust-preventive film (60 μm thick) with the following three-layer structure. Various evaluations were then performed in the same manner as in Example 1. Layer composition: Anti-corrosion layer / Intermediate layer (LLDPE1) / Outer layer (LLDPE1) = 15μm thickness / 30μm thickness / 15μm thickness

[0071] [Examples 4-28] A masterbatch was selected according to the descriptions in Tables 2-7, and a three-layer anti-corrosion film was prepared and evaluated in the same manner as in Example 3.

[0072] [Comparative Example 1] A three-layer rust-preventive film was prepared and evaluated in the same manner as in Example 3, except that the rust-preventive layer was formed using only LLDPE1.

[0073] [Summary of Results] The rust-preventive films of Examples 1 to 28 of the present invention exhibited good film-forming properties, heat-sealability, and rust prevention properties. On the other hand, the comparative film, which did not contain a rust inhibitor, showed inferior rust prevention properties.

[0074] [Table 2]

[0075] [Table 3]

[0076] [Table 4]

[0077] [Table 5]

[0078] [Table 6]

[0079] [Table 7]

[0080] <Evaluation Method> [Film forming property] The appearance of the anti-corrosion film was observed visually, and the presence or absence of defects was evaluated according to the following evaluation criteria. ○: The rust-preventive film showed no wrinkles, bumps, or peeling. ×: The rust-preventive film had wrinkles, bumps, peeling, etc.

[0081] [Heat sealability] The rust-preventive film was cut into 100mm x 100mm sections. If there was a heat-sealable outer layer, the outer layers were placed facing each other and overlapped. Then, using a heat seal tester (Tester Sangyo Co., Ltd.: TP-701-A), a 1cm x 10cm area was heat-sealed so that the edges were not heat-sealed and were split into two. The film was then cut into 15mm wide strips to create test pieces for measuring heat seal strength. Each of the bifurcated ends of this test specimen was mounted on a tensile testing machine, and the heat-sealed portion was pulled to peel it off. The heat-seal strength (N / 15mm width) was measured, and the pass / fail judgment was made according to the pass / fail criteria below. (Heat sealing conditions) Temperature: 160℃ Pressure: 1 kgf / cm² 2 Time: 1 second (Tensile strength test conditions) Test speed: 300 mm / min Load range: 50N (Criteria for determining pass / fail) ○: 30N / 15mm or more, passing the test. ×: Less than 30N / 15mm, therefore unacceptable.

[0082] [Rust-resistant] The rust-preventive film was cut into 100mm x 100mm pieces, and if there was a heat-sealable outer layer, the outer layers were placed facing each other and overlapped. Then, an impulse sealer was used to seal all four sides of the laminate, and a 100mm x 100mm pouch was produced. Next, the pouch was filled with the metal pieces described below and stored in a constant temperature bath adjusted to 60°C and 90% RH for 14 days. Changes in appearance were then evaluated according to the following evaluation criteria. (metal piece) Steel plate: Cold-rolled steel sheet (SPCC), 50mm x 50mm x 1mm, degreased. Copper plate: Tough pitch copper plate (C1100P-1 / 4H), 50mm x 50mm x 1mm, degreased. (Evaluation Criteria) ◎: No rust or discoloration, or only spot rust and slight discoloration. ○: Rust occurred on less than 10% of the surface area of ​​the test specimen. △: Rust occurred on 10% to less than 50% of the surface area of ​​the test specimen. ×: Rust occurred on more than 50% of the surface area of ​​the test specimen. [Explanation of Symbols]

[0083] 1. Rust-preventive film 2. Rust-resistant packaging materials 3. Rust-preventive layer 3a Rust Inhibitor 4. Middle Class 5 Outer layer

Claims

1. A multilayer rust-preventive film having at least a rust-preventive layer, The rust-preventive layer contains a rust inhibitor and a binder resin, and does not contain ammonium carboxylate salts. The rust inhibitor contains at least one or more selected from the group consisting of fatty acids and fatty acid esters. The number of carbon atoms in the fatty acid portion of the aforementioned fatty acid and fatty acid ester is 6 or more and 20 or less. The fatty acid ester is an alcohol ester of a fatty acid, or a glycerol fatty acid ester. One side of the rust-preventive layer has a layer containing a thermoplastic resin laminated on it. The rust-preventive layer is located on the surface of the rust-preventive film. A rust-preventive film characterized by the following features.

2. The rust-preventive film according to claim 1, characterized in that the rust-preventive film is a co-extruded film.

3. The rust-preventive film according to claim 1 or 2, wherein the rust-preventive film further comprises an intermediate layer.

4. The aforementioned rust inhibitor further contains a metal fatty acid, The number of carbon atoms in the fatty acid portion of the metal fatty acid is 6 or more and 20 or less. The metallic fatty acid is an alkali metal salt or alkaline earth metal salt of a fatty acid. A rust-preventive film according to any one of claims 1 to 3, characterized in that...

5. The rust-preventive film according to any one of claims 1 to 4, characterized in that the rust inhibitor further contains an antioxidant and an alkaline agent that exhibits alkalinity and neutralizes acidic substances.

6. The antioxidant contains a phenolic antioxidant and / or a phosphorus-based antioxidant. The rust-preventive film according to claim 5, characterized by the following:

7. The rust-preventive film according to claim 5 or 6, characterized in that the alkaline agent contains one or more selected from the group consisting of alkali metal compounds, alkaline earth metal compounds, and aluminum compounds.

8. A rust-preventive packaging material characterized by comprising a rust-preventive film according to any one of claims 1 to 7.

9. A rust-preventive packaging body characterized by being made of the rust-preventive packaging material described in claim 8.

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