JP7697204B2 - Anti-rust film and anti-rust packaging material - Google Patents

Description

This disclosure relates to an anti-rust film that inhibits rust from occurring in packaged contents, and an anti-rust package having this anti-rust film.

Packaging materials are being developed for the purpose of transporting or long-term storing metal-containing articles, such as metal articles made of metal materials or parts using metal, and there is a demand for packaging materials that have higher and more stable rust prevention properties and that have a simple layer structure and can be produced by a simple manufacturing process so as to maintain the functions and properties of the metal articles contained therein.
For example, Patent Documents 1 to 3 describe packaging laminates in which a highly volatile rust inhibitor that volatilizes at room temperature and exerts a rust-preventing effect is contained in a resin for the purpose of preventing rust on metal articles.
However, in the case of the rust-preventive film using the volatile rust-preventive agent, if the sealing property of the package produced from the rust-preventive film is insufficient, there is a problem that the rust-preventive effect on the contents is hardly exhibited. In addition, the volatile rust-preventive agent may contain substances harmful to the human body (e.g., carcinogenicity, etc.), and it is necessary to be careful when handling it. Therefore, a rust-preventive film that does not use a volatile rust-preventive agent is desired.

JP 2010-254350 A JP 2007-308726 A JP 2010-052751 A

This disclosure has been made in light of the above-mentioned circumstances, and its main objective is to provide an anti-rust film that can suppress the occurrence of rust on the packaged contents with a simple layer structure without using a volatile anti-rust agent.

The rust-preventive film of the present disclosure has a first layer and a second layer laminated on one side of the first layer, the first layer being composed of an olefin resin having heat sealability, the first layer having additives including an antioxidant, a neutralizing agent, an antiblocking agent, and a slip agent, the content of the antioxidant in the first layer being 50 ppm or more and 100 ppm or less, the content of the neutralizing agent in the first layer being 50 ppm or more and 100 ppm or less, the content of the antiblocking agent in the first layer being 50 ppm or more and 100 ppm or less, and the content of the slip agent in the first layer being 50 ppm or more and 100 ppm or less.

In the rust-preventive film of the present disclosure, the second layer may be composed of an olefin resin, and the total content of the additives contained in the second layer may be greater than the total content of the additives contained in the first layer.

The rust-preventive film of the present disclosure may have a substrate layer laminated on the second layer.

In the rust-preventive film of the present disclosure, the substrate layer may be a barrier substrate layer.

In the rust-preventive film of the present disclosure, the antioxidant may contain a phenol-based antioxidant.

In the rust-preventive film of the present disclosure, the neutralizing agent may contain calcium oxide.

In the rust-preventive film of the present disclosure, the antiblocking agent may contain sodium aluminosilicate.

In the rust-preventive film of the present disclosure, the slip agent may contain stearic acid.

The rust-resistant packaging of the present disclosure is constructed from the rust-resistant film and has the first layer on the inside.

The rust-resistant packaging of the present disclosure may be sealed at a pressure inside the packaging that is lower than atmospheric pressure.

According to the present disclosure, it is possible to provide a rust-preventive film that can suppress the occurrence of rust on the packaged contents with a simple layer structure without using a volatile rust inhibitor.

1 is a schematic cross-sectional view showing an example of a layer structure of an anti-rust film according to the present disclosure. 1 is a schematic cross-sectional view showing another example of the layer structure of the rust-preventive film of the present disclosure.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the size and ratio of components may be changed or exaggerated for ease of understanding. In addition, parts that are unnecessary for the explanation or repeated reference symbols may be omitted for ease of viewing.
Although not shown in the drawings, a functional layer such as an adhesive layer may be provided between each of the layers.
Furthermore, if necessary, in order to strengthen the adhesive strength (adhesion strength) between each layer, the laminated surfaces of each layer may be previously subjected to a physical surface treatment such as corona discharge treatment, ozone treatment, plasma treatment, glow discharge treatment, sandblasting treatment, etc., or a chemical surface treatment such as an oxidation treatment using chemicals.

(Anti-rust film)
Fig. 1 is a schematic cross-sectional view showing an example of the layer structure of the rust-preventive film of the present disclosure. The rust-preventive film 1 shown in Fig. 1 has a first layer 11 and a second layer 12 laminated on one surface of the first layer 11.
In the rust-preventive film 1 shown in Fig. 1, the first layer 11 is a single layer, but the first layer of the rust-preventive film of the present disclosure may be composed of multiple layers. Similarly, in the rust-preventive film 1 shown in Fig. 1, the second layer 12 is a single layer, but the second layer of the rust-preventive film of the present disclosure may be composed of multiple layers.

2 is a schematic cross-sectional view showing another example of the layer structure of the rust-preventive film of the present disclosure. The rust-preventive film of the present disclosure may have a base layer laminated on the second layer.
For example, the rust-preventive film 2 shown in FIG. 2 has a second layer 12 laminated on a first layer 11 , and further has a base layer 13 laminated on the second layer 12 .
In the rust-preventive film 2 shown in FIG. 2, the substrate layer 13 is a single layer, but the substrate layer of the rust-preventive film of the present disclosure may be composed of multiple layers.

An adhesive layer may also be provided between each layer of the rust-preventive film 1 shown in FIG. 1 and the rust-preventive film 2 shown in FIG. 2.

The thickness of the rust-preventive film of the present disclosure is not particularly limited, but is preferably 25 μm or more and 200 μm or less. If the thickness of the rust-preventive film is thinner than the above range, the rust-preventive film may have a problem of being too low in rigidity or easily torn. In addition, it may be difficult for the rust-preventive film to exhibit a good balance of sufficient support, rust prevention effect, heat sealability, etc. On the other hand, if the thickness of the rust-preventive film is thicker than the above range, the rigidity of the rust-preventive film may be too high, making it difficult to use as a packaging material.

The anti-rust film is preferably transparent, and more preferably has a high degree of transparency, because an anti-rust package produced from an anti-rust film with high transparency allows the contents to be easily visually confirmed.
Anti-rust films are usually used in combination with other packaging materials for steel packaging, and it is often necessary to distinguish them from transparent general-purpose olefin films (polyethylene, polypropylene). For this reason, they are supplied as light-colored films with added colorants such as blue, orange, yellow, and green, and are manufactured with a transparency that allows the contents (steel) to be seen.
Although such colored films are light in color when used alone and the difference in color between them and films containing no added colorants is small, when rolled up they are clearly distinguishable from other packaging materials.

The term "transparent" means that the film has a degree of transparency that allows one to see through the anticorrosive film from one side to the other side, and preferably has a visible light transmittance of, for example, 90% or more. The visible light transmittance is specified as the average value of the transmittance at each wavelength when measured using a spectrophotometer (Shimadzu Corporation's "UV-3100PC", compliant with JIS K 0115) in the measurement wavelength range of 380 nm to 780 nm.
For this reason, the haze of the anticorrosive film is set to be less than 20%. The haze value is measured in accordance with JIS K7136 using, for example, a haze meter HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.

In the anti-rust film of the present disclosure, in order to avoid affecting the anti-rust effect of the first layer 11, no colorant is added to the first layer 11, but a colorant is added to the second layer 12 or the base layer 13 formed on the first layer 11.
In particular, in the case of a configuration such as the rust-preventive film 2 shown in FIG. 2 , which has a second layer 12 laminated on a first layer 11 and further has a base layer 13 laminated on the second layer 12, by adding a colorant only to the second layer 12, even if the base layer 13 comes into contact with the first layer 11 when the rust-preventive film 2 is wound up, more specifically, even if the outer surface of the base layer 13 comes into contact with the inner surface of the first layer 11 (i.e., the surface of the first layer 11 that comes into contact with the contents as a package), it is possible to avoid the colorant affecting the rust-preventive properties of the first layer 11, because no colorant has been added to the base layer 13.

(1st layer)
The first layer 11 of the rust-preventive film of the present disclosure is made of an olefin resin having heat sealability, and contains, as additives, predetermined amounts of an antioxidant, a neutralizing agent, an antiblocking agent, and a slip agent.
Specifically, the content of the antioxidant in the first layer 11 is 50 ppm or more and 100 ppm or less. The content of the neutralizing agent in the first layer 11 is 50 ppm or more and 100 ppm or less. The content of the antiblocking agent in the first layer 11 is 50 ppm or more and 100 ppm or less. The content of the slip agent in the first layer 11 is 50 ppm or more and 100 ppm or less.

The first layer 11 of the rust-preventive film of the present disclosure has the second layer 12 on one side thereof, and the side opposite to the side having the second layer 12 will be in contact with an article having a metal, which is the content to be packaged by the rust-preventive film of the present disclosure, at least a part of which is in contact with the article. For example, when the rust-preventive film 1 shown in FIG. 1 is used as a package, the first layer 11 side becomes the inner layer (i.e., the inner layer) of the package, and the second layer 12 side becomes the outer layer (i.e., the outer layer) of the package. Also, when the rust-preventive film 2 shown in FIG. 2 is used as a package, the first layer 11 side becomes the inner layer (i.e., the inner layer) of the package, and the base layer 13 side becomes the outer layer (i.e., the outer layer) of the package.

And since the above-mentioned additives contained in the first layer 11 of the rust-preventive film of the present disclosure are present in the above-mentioned specified amounts, the rust-preventive film of the present disclosure exerts a rust-preventive effect on the contents packaged in the rust-preventive film of the present disclosure while ensuring stable film-forming properties during production of the rust-preventive film.

The thickness of the first layer 11 of the rust-proof film of the present disclosure can be appropriately set within the range of the thickness of the rust-proof film, 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.
When the thickness of the first layer 11 is within the above range, a sufficient rust-preventing effect can be exhibited, and the rigidity of the entire rust-preventing film can be made appropriate.
On the other hand, if the thickness of the first layer 11 is thinner than the above range, there is a risk that the rust-preventing effect will not be sufficient, and if the thickness of the first layer 11 is thicker than the above range, there is a risk that the rust-preventing effect will not be significantly improved and the rigidity of the entire rust-preventing film will be too high, making it difficult to use as a packaging material.

<Olefin Resin>
The olefin resin constituting the first layer 11 of the rust-preventive film of the present disclosure is preferably a resin having an affinity suitable for dispersing the rust inhibitor and excellent film-forming properties, and more preferably a resin having heat sealability. As the olefin resin, one or more selected from polyolefin-based polymers, that is, olefin homopolymers and/or copolymers using olefins as monomers, can be selected and used.

Examples of the olefin (olefin monomer) constituting the polyolefin polymer include ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene.
Therefore, examples of polyolefin polymers include ethylene polymers, propylene polymers, 1-butene polymers, 1-hexene polymers, 4-methyl-1-pentene polymers, etc. These polymers may be used alone or in combination of two or more. In other words, the polyolefin polymer may be a mixture of various polymers.

Among the above, ethylene-based polymers include ethylene homopolymers (polyethylene) and copolymers of ethylene and other monomers (ethylene copolymers).

Examples of ethylene homopolymers include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE).

Examples of the ethylene copolymer include an ethylene-propylene copolymer, an ethylene-1-butene copolymer, an ethylene-1-pentene copolymer, an ethylene-1-hexene copolymer, an ethylene-1-octene copolymer, and an ethylene-4-methyl-1-pentene copolymer.
Of these, linear low density polyethylene (LLDPE) polymerized with a metallocene catalyst and having a density of 0.89 g/cm ³ or more and 0.93 g/cm ³ or less is preferably used because of its excellent heat sealability, strength, touch and flexibility.
The ethylene units (structural units derived from ethylene) contained in the ethylene copolymer need only account for more than 50% of the total number of structural units (usually 99.999% or less), but can be, for example, 80% or more and 99.999% or less, or 90% or more and 99.995% or less, or even 99.0% or more and 99.990% or less, of the total number of structural units.

Examples of the propylene polymer include propylene homopolymers (polypropylene) and copolymers of propylene and other monomers (propylene copolymers). Examples of the propylene copolymers include propylene-ethylene copolymers, propylene-1-butene copolymers, propylene-1-pentene copolymers, and propylene-1-octene copolymers.
Polypropylene is generally classified into homopolymers (homopolypropylene) that are highly rigid and are polymerized only with propylene, random polymers (random polypropylene) that are highly transparent and flexible and are copolymerized with a small amount of ethylene, and block copolymers with high impact resistance and in which rubber components (EPR) are uniformly and finely dispersed in homo-random polymers. Among these, homopolypropylene has excellent odor blocking properties.
The propylene units (structural units derived from propylene) contained in the propylene copolymer may account for 50% or more (usually 99.999% or less) of the total number of structural units, but can be, for example, 80% or more and 99.999% or less, or 90% or more and 99.995% or less, or even 99.0% or more and 99.990% or less.

The density of the polyolefin resin is preferably 0.880 g/cm ³ or more and 0.950 g/cm ³ or less from the viewpoint of processability.

From the viewpoint of mechanical strength and processability, the melt flow rate (MFR) is preferably in the range of 1.0 g/10 min to 10.0 g/10 min. By having an appropriate viscosity during melt processing, it becomes possible to include and coat particulate saturated fatty acids in the resin, and it becomes possible to prevent the saturated fatty acids from falling off from the film.

<Additives>
In the rust-preventive film of the present disclosure, the content of each of the above-mentioned additives in the first layer 11 is the above-mentioned specified content, thereby ensuring stable film-forming properties during the production of the rust-preventive film of the present disclosure while exerting an anti-rust effect on the contents packaged in the rust-preventive film of the present disclosure.
Each additive contained in the first layer 11 of the rust-preventive film of the present disclosure is preferably uniformly dispersed on the surface of the first layer 11 (more specifically, on the surface opposite to the surface having the second layer 12). The surface of the first layer 11 is the surface that comes into contact with the contents packaged by the rust-preventive film of the present disclosure, and the uniform dispersion of each additive on this surface allows the rust-preventive effect to be exerted uniformly on the contents.
It should be noted that each additive contained in the first layer 11 of the rust-preventive film of the present disclosure may be dispersed uniformly on the surface of the first layer 11 as described above, and may be dispersed, for example, with a concentration gradient in the thickness direction of the first layer 11. In other words, each additive contained in the first layer 11 of the rust-preventive film of the present disclosure may be dispersed with a concentration gradient in the thickness direction of the first layer 11, but is preferably dispersed uniformly in the plane direction of the first layer 11.

Each additive contained in the first layer 11 of the rust-preventive film of the present disclosure is preferably contained using a master batch in which each additive is melt-blended at a high concentration with an olefin resin, because this makes it easier to incorporate each predetermined additive in a uniformly dispersed state in the first layer 11 of the rust-preventive film of the present disclosure.
Each of the additives and the olefin resins melt-blended into the master batch may be one type or two or more types. Also, one master batch may contain one type or two or more types of each additive.
The olefin resin used in the masterbatch may be the same as or different from the main olefin resin constituting the first layer 11 of the rust-preventive film of the present disclosure.

The content of each of the four additives (antioxidant, neutralizer, antiblocking agent, and slip agent) in the first layer 11 of the rust-preventive film of the present disclosure is preferably in the range of 50 ppm to 100 ppm. If the content of each additive is in this range, the rust-preventive film of the present disclosure can exhibit a sufficient rust-preventive effect while maintaining the film-forming property and the quality stability during long-term storage.
On the other hand, if the content of each additive is less than 50 ppm, the film-forming property and the stability of quality during long-term storage are likely to deteriorate, which is not preferable, and if the content of each additive is more than 100 ppm, it is difficult to achieve a sufficient rust-preventing effect, which is also not preferable.

The reason why it becomes difficult to achieve a sufficient rust-preventing effect when the content of each additive exceeds 100 ppm has not been fully elucidated. However, this phenomenon has been confirmed in evaluation tests, as in the examples described below. For example, it is thought that the master batch used to uniformly disperse each additive contains corrosive substances that cause rust. However, it is difficult to identify the presence of these corrosive substances, as the content is expected to be extremely small.

Therefore, in the rust-preventive film of the present disclosure, by setting the above-mentioned additives to the specified content, it is possible to ensure film-forming properties and quality stability during long-term storage while minimizing the amount of corrosive substances and other contaminants, thereby exerting a rust-preventive effect on the contents packaged in the rust-preventive film of the present disclosure.

<Antioxidants>
Additives contained in the first layer 11 of the rust-resistant film of the present disclosure include antioxidants.
As the antioxidant, it is preferable to use a primary antioxidant that captures generated radicals in combination with a secondary antioxidant that decomposes hydroperoxides generated from the radicals, and an antioxidant having both the functions of a primary antioxidant and a secondary antioxidant may also be used.
Examples of primary antioxidants include phenol-based antioxidants, amine-based antioxidants, and hindered amine-based antioxidants. Examples of secondary antioxidants include phosphorus-based antioxidants and sulfur-based antioxidants. Examples of antioxidants having both the functions of a primary antioxidant and a secondary antioxidant include hydroxylamine-based antioxidants.
The antioxidant contained in the first layer of the rust-preventive film of the present disclosure is preferably a phenol-based antioxidant, one containing a phenol-based antioxidant and a phosphorus-based antioxidant, or a hydroxylamine-based antioxidant, and among these, one having a hydrophilic group and a hydrophobic group is more preferred.
Furthermore, the phosphorus-based antioxidant and the hydroxylamine-based antioxidant also function to prevent discoloration of the polyethylene film.

Examples of phenolic antioxidants include the following:
Examples of monophenol-based antioxidants include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.
Examples of the bisphenol-based antioxidant include 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis-(4-ethyl-6-tert-butylphenol), 4,4'-thiobis-(3-methyl-6-tert-butylphenol), 4,4'-butylidene-bis-(3-methyl-6-tert-butylphenol), 3,9-bis[{1,1-dimethyl-2-{β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl}2,4,9,10-tetraoxaspiro]5,5-undecane, and the like.
Examples of polymeric phenolic antioxidants include 1,1,3-tris-(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis-{methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate}methane, bis{(3,3'-bis-4'-hydroxy-3'-tert-butylphenyl)butyric acid}glycol ester, 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol (vitamin E).
Among the above, tetrakis-{methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate}methane is particularly preferred as the phenol-based antioxidant.

Examples of phosphorus-based antioxidants (also called phosphite-based antioxidants) include the following:
For example, triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenyl-di-tridecyl)phosphite, cyclic neopentane tetrayl bis(octadecyl phosphite), tris(mono and/or dinonylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, diisodecyl pentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenathren-10-oxide, 10-(3,5-di-tert-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa Examples of the phosphatidyl ether include 10-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, cyclic neopentanetetraylbis(2,4-di-tert-butylphenyl)phosphite, cyclic neopentanetetraylbis(2,6-di-tert-butylphenyl)phosphite, 2,2-methylenebis(4,6-tert-butylphenyl)octylphosphite, and 2,4,8,10-tetratert-butyl-6-(3-(3-methyl-4-hydroxy-5-tert-butylphenyl)propoxy)dibenzo(d,f)(1,3,2)dioxaphosphepine.
Among the above, tris(2,4-di-tert-butylphenyl)phosphite is particularly preferable.

The content of the antioxidant in the first layer 11 of the rust-preventive film of the present disclosure is preferably in the range of 50 ppm to 100 ppm. When the content of the antioxidant is in this range, the rust-preventive film of the present disclosure can exhibit a sufficient rust-preventive effect while maintaining the stability of film-forming properties and quality during long-term storage.
On the other hand, if the content of the antioxidant is less than 50 ppm, the film-forming property and the stability of the quality during long-term storage tend to deteriorate, which is undesirable, and if the content of the antioxidant is more than 100 ppm, it is undesirable because it becomes difficult to exhibit a sufficient rust-preventing effect.
In addition, when two or more antioxidants are added, the total amount of the antioxidants is defined as the added amount of the antioxidants. In other words, when two or more antioxidants are included in the first layer 11 of the rust-preventive film of the present disclosure, the total amount of the antioxidants is defined as the content of the antioxidants.

<Neutralizing agent>
The additives contained in the first layer 11 of the rust-preventive film of the present disclosure also include a neutralizing agent. The neutralizing agent is added for the purpose of incorporating chlorine ions contained in polyethylene polymerized by a Ziegler catalyst, and is selected from hydrotalcites, silicates, metal oxides, metal hydroxides, fatty acid metal salts, and the like.

Hydrotalcites include those that do not contain water-containing basic carbonates of magnesium, calcium, zinc, _aluminum , bismuth, etc., or water of crystallization, and natural _and synthetic products can be used. _Natural products include those with the structure _Mg6Al2 (OH) _16CO3.4H2O . Examples of synthetic products include _Mg0.7Al0.3 (OH) ₂ ( _{CO3 ) 0.15.0.54H2O , Mg4.5Al2} (OH) _13CO3.3.5H2O , _{Mg4.2Al2 ( OH ) 12.4CO3 , Zn6Al2 ( OH} ) _{16CO3.4H2O , Ca6Al2} ( _{OH)16CO3.4H2O , and Mg14Bi2 ( OH ) 29.6.4.2H2O .}

Examples of silicates include aluminum silicate and calcium silicate. Examples of metals in metal oxides and metal hydroxides include metals in Group II of the periodic table, zinc, aluminum, tin, lead, etc. Among such metal oxides and metal hydroxides, magnesium oxide, calcium oxide, zinc oxide, aluminum oxide, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, etc. are often used.

The content of the neutralizer in the first layer 11 of the rust-preventive film of the present disclosure is preferably in the range of 50 ppm to 100 ppm. If the content of the neutralizer is in this range, the rust-preventive film of the present disclosure can exhibit a sufficient rust-preventive effect while maintaining the stability of film-forming properties and quality during long-term storage.
On the other hand, if the content of the neutralizing agent is less than 50 ppm, the film-forming property and the stability of the quality during long-term storage tend to deteriorate, which is not preferable, and if the content of the neutralizing agent is more than 100 ppm, it is difficult to achieve a sufficient rust-preventing effect, which is not preferable.
In addition, when two or more kinds of neutralizers are added, the total amount of the neutralizers is defined as the amount of the neutralizers added. In other words, when two or more kinds of neutralizers are included in the first layer 11 of the rust-preventive film of the present disclosure, the total amount of the neutralizers is defined as the content of the neutralizers.

<Anti-blocking agent>
The additives contained in the first layer 11 of the rust-preventive film of the present disclosure also include an antiblocking agent. The antiblocking agent is added for the purpose of preventing adhesion between films. The antiblocking agent has the effect of roughening the surface condition of the film by adding inorganic fine particles, and various natural or artificial inorganic minerals such as silica, clay, talc, diatomaceous earth, feldspar, kaolin, zeolite, kaolinite, wollastonite, sericite, aluminosilicate, calcium aluminosilicate, etc. are used. Among these, aluminosilicates such as sodium aluminosilicate are often used.

The content of the antiblocking agent in the first layer 11 of the rust-preventive film of the present disclosure is preferably in the range of 50 ppm to 100 ppm. When the content of the antiblocking agent is in this range, the rust-preventive film of the present disclosure can exhibit a sufficient rust-preventive effect while maintaining the stability of film-forming properties and quality during long-term storage.
On the other hand, if the content of the antiblocking agent is less than 50 ppm, the film-forming property and the stability of the quality during long-term storage tend to deteriorate, which is not preferable, whereas if the content of the antiblocking agent is more than 100 ppm, it is not preferable because it becomes difficult to exhibit a sufficient rust-preventing effect.
In addition, when two or more kinds of antiblocking agents are added, the total amount of the antiblocking agents is defined as the amount of the antiblocking agents added. In other words, when two or more kinds of antiblocking agents are included, the content of the antiblocking agents contained in the first layer 11 of the rust-preventive film of the present disclosure is defined as the total amount of the antiblocking agents.

<Slip agent>
The additives contained in the first layer 11 of the rust-preventive film of the present disclosure also include a slip agent. A slip agent (also called a lubricant) is added for the purpose of maintaining the physical stability of the material during processing, such as preventing adhesion to the metal surface of the processing device, reducing friction with the metal surface, and improving the fluidity of the material, when the thermoplastic resin is heated and molded.
As the slip agent, fatty acids are used, including fatty acids, metallic fatty acids, and fatty acid esters. Specific fatty acids include caproic acid, heptanoic acid, nonanoic acid, octanoic acid, decanoic acid, undecylic acid, lauric acid, stearic acid, nonadecylic acid, and arachidic acid.

Examples of metallic fatty acids include alkali metal salts and alkaline earth metal salts of the above fatty acids, and more specifically, calcium stearate, zinc stearate, magnesium stearate, etc. These are known to also function as neutralizing agents as described above. In the first layer of the rust-preventive film of the present disclosure, when a metallic fatty acid is used as a slip agent, a metallic fatty acid is not used as a neutralizing agent.

Examples of fatty acid esters include alcohol esters of the above fatty acids and glycerin fatty acid esters. As for the glycerin fatty acid esters, glycerin trifatty acid esters are preferred, glycerin fatty acid esters are more preferred, and glycerin tricaprylic acid ester is more preferred.

The content of the slip agent in the first layer 11 of the rust-preventive film of the present disclosure is preferably in the range of 50 ppm to 100 ppm. If the content of the slip agent is in this range, the rust-preventive film of the present disclosure can exhibit a sufficient rust-preventive effect while maintaining the stability of film-forming properties and quality during long-term storage.
On the other hand, if the content of the slip agent is less than 50 ppm, the film-forming property and the stability of the quality during long-term storage tend to deteriorate, which is undesirable, and if the content of the slip agent is more than 100 ppm, it is undesirable because it becomes difficult to exhibit a sufficient rust-preventing effect.
In addition, when two or more slip agents are added, the total amount of the slip agents is defined as the amount of the slip agents added. In other words, when two or more slip agents are added, the content of the slip agent contained in the first layer 11 of the rust-preventive film of the present disclosure is defined as the total amount of the slip agents added.

<Other additives>
The rust-preventive film of the present disclosure may contain trace amounts of various plastic compounding agents and additives other than the above-mentioned antioxidants, neutralizing agents, antiblocking agents, and slip agents, for example, for the purpose of improving or modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, releasability, flame retardancy, antifungal properties, electrical properties, strength, etc. However, the content is limited to a range in which the rust-preventive effect of the first layer of the rust-preventive film of the present disclosure is not reduced.
In the above, examples of common compounding agents that may be included include crosslinking agents, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, and the like.

(Second layer)
As described above, when the rust-proof film of the present disclosure is used as a package, the first layer 11 side becomes the inner layer (i.e., the inner layer) of the package, and the second layer 12 side becomes the outer layer (i.e., the outer layer) of the package relative to the first layer 11.
More specifically, for example, when the rust-preventive film 1 shown in Fig. 1 is used as a package, the first layer 11 side becomes the inner layer (i.e., the inner layer) of the package, and the second layer 12 side becomes the outer layer (i.e., the outer layer) of the package. Also, when the rust-preventive film 2 shown in Fig. 2 is used as a package, the first layer 11 side becomes the inner layer (i.e., the inner layer) of the package, and the base layer 13 side becomes the outer layer (i.e., the outer layer) of the package.
The second layer 12 of the rust-preventive film of the present disclosure may be a single layer or may be configured with multiple layers.

In the rust-preventive film of the present disclosure, the second layer 12 is composed of an olefin resin, and the total content of the additives contained in the second layer 12 is greater than the total content of the additives contained in the first layer 11.
Therefore, even if the content of the above-mentioned four types of additives (antioxidant, neutralizer, antiblocking agent, and slip agent) in the first layer 11 of the rust-resistant film of the present disclosure is in the range of 50 ppm or more and 100 ppm or less, which is smaller than that of a normal film, by making the rust-resistant film of the present disclosure have a laminated structure of the first layer 11 and the second layer 12 and making the content of the additives in the second layer 12 close to that of a normal film, the film-forming properties of the rust-resistant film of the present disclosure and the quality stability during long-term storage can be further improved.
In addition, in the rust-preventive film 1 shown in FIG. 1, the content of the slip agent contained in the second layer 12 can be optimized to suppress the occurrence of pinholes caused by friction during transportation.

As described above, in the case of a configuration having a base layer 13 on the second layer 12, such as the rust-preventive film 2 shown in FIG. 2, by adding a colorant only to the second layer 12, even if the base layer 13 comes into contact with the first layer 11 when the rust-preventive film 2 is wound up, or more specifically, even if the outer surface of the base layer 13 comes into contact with the inner surface of the first layer 11 (i.e., the surface of the first layer 11 that comes into contact with the contents as a package), since no colorant is added to the base layer 13, it is possible to avoid the colorant affecting the rust-preventive properties of the first layer 11.

As the olefin resin constituting the second layer 12 of the rust-preventive film of the present disclosure, similar to the olefin resin contained in the first layer 11 described above, one or more selected from polyolefin-based polymers, that is, olefin homopolymers and/or copolymers using olefins as monomers, can be selected and used. The olefin resin used in the second layer 12 may be the same as or different from the olefin resin constituting the first layer 11.

The thickness of the second layer 12 of the rust-preventive film of the present disclosure can be set appropriately within the range of the thickness of the rust-preventive film, but is preferably 10 μm or more and 100 μm or less. If the thickness of the second layer 12 is within the above range, there is little risk of it having a significant adverse effect on the heat sealability and film formability of the entire rust-preventive film.

(Base material layer)
The substrate layer 13 may be a layer that can impart various functions to the rust-preventive film of the present disclosure, such as mechanical, physical, and chemical functions, such as support, rigidity, flexibility, pinhole resistance, etc. For example, when a barrier substrate layer having a barrier property against water vapor is used as the substrate layer 13, the penetration of moisture into the interior of a package produced from the rust-preventive film of the present disclosure can be effectively prevented.
The thickness of the base layer 13 can be set appropriately within the range of the thickness of the anti-rust film, but if the purpose is to impart appropriate strength and stiffness to the anti-rust film, it is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

<Barrier Substrate Layer>
The barrier substrate layer has a resin layer and an inorganic oxide film provided on one surface of the resin layer.
The resin layer functions as a support layer for the inorganic oxide film in the barrier substrate layer. As the resin layer, various resins having strength, heat resistance, etc. can be used. Specifically, resin films such as polyester resins, polyamide resins, polyaramid resins, polyolefin resins, polycarbonate resins, polystyrene resins, polyacetal resins, and fluorine resins can be used. In particular, polyethylene terephthalate (PET) films are preferably used for reasons such as printability, vapor deposition suitability, and antistatic properties of vapor deposition.
The resin layer may be either an unstretched film or a uniaxially or biaxially stretched film.

In addition, examples of materials that can be used to form the inorganic oxide film include oxides such as silicon oxide, aluminum oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide. Among these, aluminum oxide, silicon oxide, and magnesium oxide are preferred in terms of barrier performance and production efficiency.

The inorganic oxide film may be a single layer structure formed by a single deposition process, or a multilayer structure formed by repeating the deposition process multiple times. In the case of a multilayer structure, each layer may be made of the same material or different materials. In addition, each layer may be formed by the same formation method or different formation methods.

The thickness of the inorganic oxide film can be set in the range of 5 nm to 100 nm inclusive as the total thickness of the film. By setting the thickness of the inorganic oxide film within the above range, a barrier substrate layer with excellent flexibility and pinhole resistance can be obtained.

On the other hand, if the thickness of the inorganic oxide film exceeds 100 nm, the flexibility decreases, and there is a risk that the inorganic oxide film may crack due to external forces such as bending or pulling. Therefore, it becomes difficult to achieve sufficient barrier performance. In addition, the stress of the material itself increases, which is not preferable. In addition, the productivity is significantly reduced, and protrusions tend to be formed due to the growth of abnormal grains, which is also not preferable.
Furthermore, if the thickness of the inorganic oxide film is less than 5 nm, the film properties are poor and pinholes are likely to occur, making it difficult to achieve sufficient barrier performance.

Methods for forming an inorganic oxide film include, for example, physical vapor deposition methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. In the present disclosure, the deposition method in the vacuum deposition method is preferable, and a resistance heating method, induction heating method, electron beam heating method, etc. can be appropriately selected and used as necessary.

In particular, in the present disclosure, it is preferable to provide an inorganic oxide film by a vacuum deposition method using a resistance heating method. In the vacuum deposition method using a resistance heating method, the deposition material is heated by Joule heat using an electric resistor, and compared to other heating methods, it is possible to form a uniform deposition film because the deposition material is heated overall. In addition, the line speed can be set high. In addition, the vacuum deposition method using a resistance heating method can suppress charging of the film.
In the present disclosure, it is particularly preferable to provide an aluminum oxide vapor deposition film as the inorganic oxide film by a resistance heating type vacuum deposition method from the viewpoints of barrier performance, antistatic properties, cost, and the like.

(Method of manufacturing anti-rust film)
The method for producing the rust-preventive film of the present disclosure will be described below. Note that the production method described below is only an example and does not limit the present disclosure.
Each layer constituting the rust-preventive film of the present disclosure can be produced by any method such as a T-die extrusion method, an extrusion inflation method, or the like.
Lamination of each layer of the rust-preventive film having a multi-layer structure can be performed by any method such as, in addition to the T-die coextrusion method and the coextrusion inflation method, a wet lamination method, a dry lamination method, a solventless dry lamination method, an extrusion lamination method, a coextrusion lamination method, etc. Among the above, the T-die coextrusion method and the coextrusion inflation method are preferable in terms of cost because they can reduce the number of steps compared to the lamination method.

For example, the case of producing the rust-preventive film of the present disclosure by a co-extrusion inflation method will be described. Note that, although the method of producing a rust-preventive film having a two-layer structure of a first layer 11 and a second layer 12 will be described here, a rust-preventive film having a three-layer structure of a first layer 11, a second layer 12, and a substrate layer 13 can also be produced in the same manner.
When the above-mentioned barrier substrate layer is provided as the substrate layer 13, the substrate layer 13 can be manufactured by laminating the surface of the above-mentioned barrier substrate layer having the inorganic oxide film 42 to the exposed surface of the second layer 12 laminated on the first layer 11.

To manufacture a rust-preventive film having a two-layer structure of a first layer 11 and a second layer 12, first, resin compositions for forming the first layer 11 and the second layer 12 are prepared. The first layer 11 and the second layer 12 are then co-extruded and laminated by inflation film formation to manufacture a rust-preventive film having a two-layer structure. An aging treatment may be performed as necessary. The obtained rust-preventive film may also be stretched uniaxially or biaxially as necessary.

The anticorrosive film can be subjected to secondary processing for the purpose of imparting surface functions such as chemical functions, electrical functions, magnetic functions, mechanical functions, friction/wear/lubrication functions, optical functions, thermal functions, and biocompatibility.
Examples of secondary processing include embossing, painting, adhesive, printing, metallizing (plating, etc.), machining, surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromic treatment, physical vapor deposition, chemical vapor deposition, coating, etc.), etc. The rust-resistant film can also be subjected to lamination (dry lamination or extrusion lamination), bag making, and other post-treatment processes.

(Rust-proof packaging)
The rust-preventive packaging body of the present disclosure is a packaging body used for packaging an article having metal, and has the rust-preventive film of the present disclosure. More specifically, the rust-preventive packaging body of the present disclosure is made of the rust-preventive film of the present disclosure, and has a first layer 11 on the inside.
There are no particular limitations on the shape of the rust-preventive packaging body of the present disclosure, and the rust-preventive film of the present disclosure can be folded, layered to encase the contents, or heat sealed into various shapes, and added value can also be added by printing decoration.

A pouch-shaped rust-preventive package can be produced in various shapes by, for example, folding an anti-rust film in half, or by preparing two sheets of rust-preventive film, overlapping them with the first layer surfaces facing each other, and heat-sealing the peripheral edges.
For example, rust-proof packages of various shapes can be produced by heat sealing using a heat seal configuration such as a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope seal type, a grommet seal type (pillow seal type), a pleated seal type, a flat bottom seal type, a square bottom seal type, or a gusset type.
In the above, examples of the heat sealing method that can be used include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

When manufacturing the rust-resistant package, the air inside the package may be sucked out and the package may be sealed at a pressure lower than atmospheric pressure. Also, when manufacturing the rust-resistant package, the package may be sealed while replacing the space inside the package with a gas having a low oxygen concentration and low humidity.

In the rust-preventive package of the present disclosure, the first layer 11 of the rust-preventive film of the present disclosure is located on the inner layer side of the rust-preventive package, and the second layer 12 is located on the outer layer side of the first layer 11. That is, in the rust-preventive package of the present disclosure, the first layer 11 is the layer that comes into contact with the metal-containing article that is the content of the package.
By adopting such a positional relationship, the rust-preventive package of the present disclosure can suppress the occurrence of rust on the metal-containing article as the content. In addition, in the rust-preventive film of the present disclosure, the second layer 12, which is the outer layer side, can contain a required amount of additives according to various purposes, so that the film formability and quality stability during long-term storage of the rust-preventive film of the present disclosure can be further improved.
In addition, in the rust-preventive film 1 shown in FIG. 1, the content of the slip agent contained in the second layer 12 can be optimized to suppress the occurrence of pinholes caused by friction during transportation.

The rust-preventive packaging body of the present disclosure may also have a base layer 13 on top of the second layer (i.e., on the outer layer side). This allows the rust-preventive packaging body of the present disclosure to be endowed with various mechanical, physical, and chemical functions, such as support, rigidity, flexibility, and pinhole resistance.

The present disclosure will be explained in more detail with reference to the following examples and comparative examples, but the present disclosure is not limited to these examples. Details of the raw materials used in the examples and comparative examples are as follows.

[Additives]
Antioxidant: phenolic antioxidant A060 manufactured by Adeka Corporation.
Neutralizing agent: Calcium oxide HAL-J (average particle size 1 μm or more and 2 μm or less) manufactured by Yoshizawa Petrochemical Industries Co., Ltd.
Antiblocking agent (AB agent): Sodium aluminosilicate particles, AMT100S2 (pH=7), manufactured by Mizusawa Industrial Chemicals.
Slip agent: stearic acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[Olefin resin]
LDPE1: LDPE manufactured by Japan Polyethylene Co., Ltd., Novatec LC520. Density: 0.923 g/cm ³ , MFR: 3.6 g/10 min.
LLDPE1: Evolue SP2020, LLDPE manufactured by Prime Polymer Co., Ltd. Density: 0.916 g/cm ³ , MFR: 2.0 g/10 min.

<Preparation of Masterbatch>
[Preparation of Masterbatch 1]
The antioxidant and LDPE1 were melt-blended in the following ratio to obtain Masterbatch 1 (MB1).
LDPE1 95 parts by weight Antioxidant 5 parts by weight

[Preparation of Masterbatches 2 to 4]
According to the following formulation, melt blending was carried out in the same manner as for Masterbatch 1 to obtain Masterbatches 2 to 4 (MB2 to MB4).
MB2: LDPE1 95 parts by weight/neutralizing agent 5 parts by weight MB3: LDPE1 95 parts by weight/anti-blocking agent 5 parts by weight MB4: LDPE1 95 parts by weight/slip agent 5 parts by weight

[Preparation of Masterbatch 5]
The antioxidant and LDPE1 were melt-blended in the following ratio to obtain Masterbatch 5 (MB5).
LDPE1 90 parts by weight Antioxidant 10 parts by weight

[Preparation of Masterbatches 6 to 8]
According to the following formulation, melt blending was carried out in the same manner as for Masterbatch 1 to obtain Masterbatches 6 to 8 (MB6 to MB8).
MB6: LDPE1 90 parts by weight/neutralizing agent 10 parts by weight MB7: LDPE1 90 parts by weight/anti-blocking agent 10 parts by weight MB8: LDPE1 90 parts by weight/slip agent 10 parts by weight

[Example 1]
MB1, MB2, MB3, MB4, and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Example 1.
MB1 0.1 part by mass MB2 0.1 part by mass MB3 0.1 part by mass MB4 0.1 part by mass LLDPE1 99.6 parts by mass MB5, MB6, MB7, MB8 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the second layer of the rust-preventive film of Example 1.
MB5 1 part by mass MB6 1 part by mass MB7 1 part by mass MB8 1 part by mass LLDPE1 96 parts by mass The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (60 μm thick).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Example 2]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Example 2.
MB1 0.2 parts by mass MB2 0.1 parts by mass MB3 0.1 parts by mass MB4 0.1 parts by mass LLDPE1 99.5 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Example 2 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Example 3]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Example 3.
MB1 0.1 part by mass MB2 0.2 part by mass MB3 0.1 part by mass MB4 0.1 part by mass LLDPE1 99.5 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Example 3 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Example 4]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Example 4.
MB1 0.1 part by mass MB2 0.1 part by mass MB3 0.2 part by mass MB4 0.1 part by mass LLDPE1 99.5 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Example 4 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Example 5]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Example 5.
MB1 0.1 part by mass MB2 0.1 part by mass MB3 0.1 part by mass MB4 0.2 part by mass LLDPE1 99.5 parts by mass Furthermore, in the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Example 5 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Example 6]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Example 6.
MB1 0.2 parts by mass MB2 0.2 parts by mass MB3 0.2 parts by mass MB4 0.2 parts by mass LLDPE1 99.2 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Example 6 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Comparative Example 1]
MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Comparative Example 1.
MB2 0.1 parts by mass MB3 0.1 parts by mass MB4 0.1 parts by mass LLDPE1 99.7 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Comparative Example 1 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Comparative Example 2]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Comparative Example 2.
MB1 0.4 parts by mass MB2 0.1 parts by mass MB3 0.1 parts by mass MB4 0.1 parts by mass LLDPE1 99.3 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Comparative Example 2 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Comparative Example 3]
MB1, MB3, MB4 and LLDPE1 were dry blended in the following ratio to obtain a resin composition for the first layer of the rust-preventive film of Comparative Example 3.
MB1 0.1 parts by weight MB3 0.1 parts by weight MB4 0.1 parts by weight LLDPE1 99.7 parts by weight In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Comparative Example 3 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Comparative Example 4]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Comparative Example 4.
MB1 0.1 part by mass MB2 0.4 part by mass MB3 0.1 part by mass MB4 0.1 part by mass LLDPE1 99.3 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Comparative Example 4 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Comparative Example 5]
MB1, MB2, MB4 and LLDPE1 were dry blended in the following ratio to obtain a resin composition for the first layer of the rust-preventive film of Comparative Example 5.
MB1 0.1 part by mass MB2 0.1 part by mass MB4 0.1 part by mass LLDPE1 99.7 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Comparative Example 5 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Comparative Example 6]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Comparative Example 6.
MB1 0.1 part by mass MB2 0.1 part by mass MB3 0.4 part by mass MB4 0.1 part by mass LLDPE1 99.3 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Comparative Example 6 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Comparative Example 7]
MB1, MB2, MB3 and LLDPE1 were dry blended in the ratio shown below to obtain a resin composition for the first layer of the rust-preventive film of Comparative Example 7.
MB1 0.1 part by mass MB2 0.1 part by mass MB3 0.1 part by mass LLDPE1 99.7 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Comparative Example 7 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

[Comparative Example 8]
MB1, MB2, MB3, MB4 and LLDPE1 were dry blended in the following ratio to obtain a resin composition for the first layer of the rust-preventive film of Comparative Example 8.
MB1 0.1 part by mass MB2 0.1 part by mass MB3 0.1 part by mass MB4 0.4 part by mass LLDPE1 99.3 parts by mass In the same manner as in Example 1, a resin composition for the second layer of the rust-preventive film of Comparative Example 8 was obtained.
The resin composition for the first layer and the resin composition for the second layer obtained above were formed into a film and laminated at 160°C using a co-extrusion inflation method to obtain the following two-layer rust-proofing film (thickness: 60 µm).
Layer structure: 1st layer / 2nd layer = 30 μm thickness / 30 μm thickness

The following evaluations were carried out for each of the films in Examples 1 to 6 and Comparative Examples 1 to 8. The results are shown in Tables 1 and 2. In Tables 1 and 2, AB agent refers to an antiblocking agent.

<Evaluation method>
[Film forming property]
The appearance of each film was observed with the naked eye, and the presence or absence of defects was evaluated according to the following evaluation criteria.
◯: The anti-rust film had no wrinkles, bumps, peeling, etc.
×: The rust-preventive film had wrinkles, bumps, peeling, etc.

[Rust prevention]
Each film was cut into 100 mm x 100 mm pieces, and the first layers were placed facing each other and overlapped. After that, the other three sides except for one side were sealed using an impulse sealer to create a 100 mm x 100 mm pouch with one side open.
Next, the following metal pieces were placed in the pouch as contents, and the open side of the pouch was sealed while the air inside the pouch was sucked out. The pouch was then stored in a thermostatic chamber adjusted to 60°C and 90% RH for 14 days, and the change in appearance was evaluated according to the following evaluation criteria.
(metal piece)
Steel plate: cold-rolled steel plate (SPCC), 50 mm x 50 mm x 1 mm, degreased.
Copper plate: Tough pitch copper plate (C1100P-1/4H), 50 mm x 50 mm x 1 mm, degreased.
(Evaluation Criteria)
○: No rust or discoloration, or only spots of rust and slight discoloration.
×: Rust occurred on 50% or more of the area of the test piece.

1, 2 Rust-proof film 11 First layer 12 Second layer 13 Base material layer

Claims (5)

A first layer and a second layer laminated on one surface of the first layer,
the first layer is made of an olefin resin having heat sealability,
The olefin resin is polyethylene containing chloride ions,
The first layer has additives such as an antioxidant, a neutralizing agent, an antiblocking agent, and a slip agent;
the antioxidant comprises a phenolic antioxidant;
The neutralizing agent is made of calcium oxide,
the antiblocking agent is made of sodium aluminosilicate;
the slip agent comprises stearic acid;
The content of the antioxidant in the first layer is 50 ppm or more and 100 ppm or less,
The content of the neutralizing agent in the first layer is 50 ppm or more and 100 ppm or less,
the content of the antiblocking agent in the first layer is 50 ppm or more and 100 ppm or less,
The content of the slip agent in the first layer is 50 ppm or more and 100 ppm or less,
the second layer is made of an olefin resin;
the second layer has additives including a phenolic antioxidant, calcium oxide, sodium aluminosilicate, and stearic acid;
The total content of the additives contained in the second layer is
A rust-preventive film , the content of which is greater than the total content of the additives contained in the first layer . The rust-preventive film according to claim 1 , further comprising a substrate layer laminated on the second layer. The rust-preventive film according to claim 2 , wherein the substrate layer is a barrier substrate layer. A rust-preventive packaging body comprising the rust-preventive film according to any one of claims 1 to 3 , and having the first layer on the inside. 5. The rust-resistant package according to claim 4 , wherein the package is sealed at a pressure lower than atmospheric pressure.