Rust-proof film

Abstract

We provide a rust-preventive film that offers excellent rust prevention while using recycled resin. [Solution] A rust-preventive film comprising recycled polyethylene, a volatile rust inhibitor, and an antioxidant, wherein the volatile rust inhibitor is selected from carboxylic acid esters and heterocyclic aromatic compounds, and the antioxidant is a phenolic antioxidant.

Description

[Technical Field]

[0001] This disclosure relates to a rust-preventive film, and more particularly to a rust-preventive film for packaging metal components such as machine parts to suppress oxidation and rust formation on the metal surface during storage, transport, and transportation. [Background technology]

[0002] Traditionally, when storing metal components for extended periods, it was common practice to apply rust-preventive oil before packaging and storing them to prevent rust formation. For machine parts where rust prevention by applying rust-preventive oil is not possible, alternative methods include packaging and storing them with volatile rust inhibitors or rust-preventive films made by kneading volatile rust inhibitors into resin films.

[0003] In rust-preventive films using the volatile rust inhibitors described above, it is necessary to have breathability so that the volatile rust inhibitors can vaporize. In single-layer films, the volatile rust inhibitors volatilize not only inside but also outside the packaging, so a multi-layer film structure is adopted. For example, a multi-layer film has been proposed in which a resin film containing a volatile rust inhibitor is laminated with a base film such as nylon. It is said that such a multi-layer rust-preventive film can suppress the diffusion or volatilization of the volatile rust inhibitor to the outer layer (atmospheric side), and maintain a high rust-inhibiting effect over a long period of time (for example, Patent Document 1).

[0004] Furthermore, a multilayer film has been proposed that contains a volatile corrosion inhibitor in the innermost layer, a gas barrier resin layer as an intermediate layer, and a base material layer as the outermost layer. It is known that with this multilayer film, the barrier properties of the corrosion inhibitor against vaporized gas, oxygen, or water vapor are improved by providing the intermediate layer (for example, Patent Document 2, etc.).

[0005] Furthermore, to improve barrier properties, a multilayer anti-corrosion film is disclosed in which a barrier film having a vapor-deposited film and an organic coating layer on the substrate is laminated to a sealant layer (for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-059864 [Patent Document 2] Japanese Patent Publication No. 2019-155611 [Patent Document 3] Japanese Patent Publication No. 2020-189689 [Overview of the project] [Problems that the invention aims to solve]

[0007] Incidentally, in recent years, the use of recycled products has been recommended from the perspective of reducing environmental impact. In fields such as packaging films, efforts are being made to actively use recycled resin products. However, while recycled resins such as polyester and polyethylene are available on the market, recycled products for special gas barrier resins and the like are not currently available.

[0008] Furthermore, for example, recycled polyethylene may have antioxidants added to prevent thermal decomposition and gelation during the re-melting process of recycling. Phenolic antioxidants and phosphate-based antioxidants are used as such antioxidants to prevent thermal degradation of polyethylene.

[0009] In rust-preventive films containing volatile corrosion inhibitors as described above, if the recycled polyethylene constituting the resin film contains an antioxidant, the antioxidant may deactivate the volatile corrosion inhibitor, reducing the rust-preventive effect of the rust-preventive film.

[0010] Therefore, the purpose of this disclosure is to provide a rust-preventive film that has excellent rust-preventive properties while using recycled resin. [Means for solving the problem]

[0011] The present inventors have found that even when an antioxidant is contained in a recycled polyethylene resin, if the participation inhibitor is a specific compound and the vaporizable rust inhibitor used is a specific compound, the deactivation of the vaporizable rust inhibitor by the antioxidant as described above can be suppressed, and a rust-preventive film having an excellent rust-preventive effect can be realized while using the recycled resin. The present disclosure is based on such findings.

[0012] [1] A rust-preventive film comprising at least recycled polyethylene, a vaporizable rust inhibitor, and an antioxidant, wherein the vaporizable rust inhibitor is selected from carboxylic acid esters and heterocyclic aromatic compounds, and the antioxidant is a phenolic antioxidant. [2] The rust-preventive film according to [1], wherein the vaporizable rust inhibitor is contained in a proportion of 2 to 10% by mass based on the recycled polyethylene. [3] The rust-preventive film according to [1], wherein the antioxidant is contained in a proportion of 500 to 5000 ppm based on the recycled polyethylene. [4] A first layer comprising at least recycled polyethylene, a vaporizable rust inhibitor, and an antioxidant, and a second layer comprising recycled polyethylene and / or virgin polyethylene, wherein the first layer and the second layer are coextruded to form a film. [5] The rust-preventive film according to [1], wherein the recycled polyethylene has a density of 0.860 g / cm 3 or more and 0.932 g / cm 3 or less. [6] The rust-preventive film according to [5], wherein the polyethylene having a density of 0.860 g / cm 3 or more and 0.932 g / cm 3 or less is at least one selected from low-density polyethylene and linear low-density polyethylene. [Advantages of the Invention]

[0013] According to this disclosure, it is possible to provide a rust-preventive film that has excellent rust-preventive properties while using recycled resin. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a schematic cross-sectional view showing one embodiment of the anti-corrosion film of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view showing one embodiment of the anti-corrosion film of the present disclosure. [Figure 3] Figure 3 is a schematic cross-sectional view showing one embodiment of the rust-preventive film of this disclosure. [Figure 4] Figure 4 shows the GC-MS measurement results for the resin compositions of Example 1 and Comparative Example 1. [Figure 5] Figure 5 shows the GC-MS measurement results for the resin compositions of Example 1 and Comparative Example 2. [Modes for carrying out the invention]

[0015] In this specification, when multiple candidate upper limits and multiple candidate lower limits are given for a certain parameter, the numerical range of that parameter may be constructed by combining any one candidate upper limit and any one candidate lower limit. As an example, consider the statement, "Parameter B is preferably A1 or greater, more preferably A2 or greater, even more preferably A3 or greater. Parameter B is preferably A4 or less, more preferably A5 or less, even more preferably A6 or less." In this example, the numerical range of parameter B may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, or A3 or greater and A6 or less.

[0016] In this specification, polyethylene refers to a polymer in which the content ratio of ethylene-derived structural units exceeds 50 mol% in the total amount of structural units derived from polymerizable monomers. In this polymer, the content ratio of ethylene-derived structural units is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, and particularly preferably 95 mol% or more. The above content ratio is measured by nuclear magnetic resonance spectroscopy (NMR method).

[0017] In this specification, polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and an ethylenically unsaturated monomer other than ethylene. Examples of the ethylenically unsaturated monomer other than ethylene include α-olefins having 3 to 20 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene; vinyl monomers such as vinyl acetate and vinyl propionate; and (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate.

[0018] In this specification, examples of polyethylene include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylate copolymer.

[0019] In this specification, the density of polyethylene is as follows. The density of low-density polyethylene is 0.860 g / cm 3 or more and 0.932 g / cm 3 or less, more preferably 0.900 g / cm 3 or more and 0.932 g / cm 3 or less. The density of linear low-density polyethylene is 0.860 g / cm 3 or more and 0.932 g / cm 3The following, and more preferably 0.900 g / cm³ 3 More than 0.932g / cm 3 The following applies: The density of medium-density polyethylene is 0.932 g / cm³. 3 Exceeding 0.945 g / cm³ 3 The following applies: The density of high-density polyethylene is 0.945 g / cm³. 3 It exceeds, preferably 0.965 g / cm³ 3 The following applies: The density of polyethylene is measured in accordance with JIS K7112-2:2023 (density gradient pipe method, 23°C).

[0020] Low-density polyethylene is, for example, polyethylene obtained by polymerizing ethylene by high-pressure polymerization (high-pressure low-density polyethylene). Linear low-density polyethylene is, for example, polyethylene obtained by polymerizing ethylene and a small amount of α-olefin by polymerization using a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst.

[0021] Polyethylenes with different densities or branching can be obtained by appropriately selecting a polymerization method. For example, it is preferable to use a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as the polymerization catalyst, and to carry out polymerization in one or more stages using one of the following methods: gas-phase polymerization, slurry polymerization, solution polymerization, or high-pressure ionic polymerization.

[0022] The melt flow rate (MFR) of polyolefins such as polyethylene as used herein is described below. From the viewpoint of film-forming properties and processability, the above MFR is preferably 0.1 g / 10 min or more, more preferably 0.3 g / 10 min or more, even more preferably 0.5 g / 10 min or more, preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less, even more preferably 10 g / 10 min or less, and particularly preferably 5 g / 10 min or less. The above MFR is, for example, 0.1 g / 10 min or more and 30 g / 10 min or less. The MFR of polyolefins is measured by Method A under a load of 2.16 kg in accordance with JIS K7210-1:2014. The measurement temperature of the MFR is set according to the melting point of the polyolefin, etc., and is 190°C in the case of polyethylene.

[0023] In this specification, a biomass-derived resin material (hereinafter also referred to as "biomass polyethylene") may be used as polyethylene. A biomass material is, for example, a resin material obtained using biomass-derived raw materials (specifically, plant-derived raw materials) as at least a part of the raw materials. Since biomass materials are carbon-neutral materials, they can reduce the environmental burden of laminates or packaging bags.

[0024] In this specification, recycled polyethylene means polyethylene recycled from used polyethylene products by mechanical recycling or chemical recycling. Mechanical recycling generally involves crushing collected polyethylene film, washing it with alkali to remove dirt and foreign matter from the film surface, drying it at high temperature and under reduced pressure for a certain period of time to disperse contaminants remaining inside the film, decontamination, removing dirt from the film, and returning it to polyethylene. Chemical recycling generally involves decomposing collected polyethylene film down to the monomer level and then repolymerizing the monomers to obtain polyethylene. In this specification, virgin polyethylene means polyethylene that is not recycled polyethylene, but obtained using raw materials derived from fossil fuels or biomass.

[0025] The embodiments of this disclosure will be described in detail below. This disclosure can be implemented in many different forms and is not construed as being limited to the embodiments described below. The drawings may schematically represent the width, thickness, and shape of each layer, etc., compared to the embodiments, in order to clarify the explanation, but these are merely examples and do not limit the interpretation of this disclosure. In this specification and in each figure, elements similar to those already described in the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0026] The embodiments of the rust-preventive film of this disclosure will be described below with reference to the drawings as appropriate.

[0027] Figure 1 is a schematic cross-sectional view showing one embodiment of the rust-preventive film of the present disclosure. The rust-preventive film 1 according to one embodiment of the present disclosure is composed of a layer 10 containing at least recycled polyethylene, a volatile rust inhibitor, and an antioxidant. Figures 2 and 3 are schematic cross-sectional views showing another embodiment of the rust-preventive film of the present disclosure. The rust-preventive film 1 according to another embodiment of the present disclosure may be configured to include a first layer 10 containing at least recycled polyethylene, a volatile rust inhibitor, and an antioxidant, and a second layer 20 containing recycled polyethylene and / or virgin polyethylene. Furthermore, in addition to the second layer, a third layer 30 containing recycled polyethylene and / or virgin polyethylene may be further included, as shown in Figure 3. In the rust-preventive film 1 of the present disclosure shown in Figures 2 and 3, the first layer 10 containing the volatile rust inhibitor is the innermost layer when the rust-preventive film is used as packaging for metal parts, etc. Furthermore, in the rust-preventive film 1 of this disclosure shown in Figure 2, the second layer 20 is the outermost layer when used as a packaging material. Moreover, in the rust-preventive film 1 of this disclosure shown in Figure 3, the third layer 30 is the innermost layer when the rust-preventive film is used as packaging material for metal parts, etc., and the second layer 20 is an intermediate layer provided between the innermost first layer 10 and the outermost third layer 30. The following describes each layer constituting the rust-preventive film 1 of this disclosure.

[0028] When the rust-preventive film of this disclosure is composed of a single layer as shown in Figure 1, the layer contains at least recycled polyethylene, a volatile corrosion inhibitor, and an antioxidant. Recycled polyethylene, in particular mechanically recycled polyethylene, is manufactured by remelting used polyethylene as described above, and antioxidants are sometimes added at that time to prevent thermal degradation of the polyethylene. Antioxidants suppress the severing and crosslinking reactions of polyethylene molecular chains by capturing radicals produced when polyethylene is thermally decomposed during remelting. On the other hand, such antioxidants may deactivate volatile corrosion inhibitors. Among volatile corrosion inhibitors, carboxylic acid esters and heterocyclic aromatic compounds are particularly susceptible to deactivation by amine-based antioxidants. Furthermore, among volatile corrosion inhibitors, amine-based corrosion inhibitors have a similar chemical structure to amine-based antioxidants, so even if an amine-based corrosion inhibitor is used as a volatile corrosion inhibitor, it may function as an antioxidant (radical scavenger) due to the heat during film formation, resulting in a reduced rust-preventive effect of the resulting rust-preventive film. In this disclosure, a phenolic antioxidant is used as the antioxidant agent, and a carboxylic acid ester-based rust inhibitor or a heterocyclic aromatic compound is used as the volatile rust inhibitor, thereby suppressing the reduction in rust prevention effect when used as a rust-preventive film. By using such a combination of specific volatile rust inhibitors and specific antioxidants, it is possible to realize a rust-preventive film with excellent rust prevention effect while reducing the environmental impact.

[0029] When the rust-preventive film of this disclosure is composed of a single layer as shown in Figure 1, the layer contains recycled polyethylene as the main component of the resin. "Contained as the main component" means a layer in which the recycled polyethylene content is 50% by mass or more in 100% by mass of the layer. The above content is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0030] The density of recycled polyethylene is 0.860 g / cm³. 3More than 0.932g / cm 3 The following is preferable. Low-density polyethylene and linear low-density polyethylene can be suitably used as polyethylene within the density range, and linear low-density polyethylene can be more preferably used. For example, a density of 0.900 g / cm³ 3 More than 0.932g / cm 3 It is more preferable to use the following linear low-density polyethylene.

[0031] Furthermore, even when the resin component includes virgin polyethylene in addition to recycled polyethylene, the density of virgin polyethylene is 0.860 g / cm³. 3 More than 0.932g / cm 3 Preferably, the following, and more preferably, linear low-density polyethylene can be used. For example, a density of 0.900 g / cm³ 3 More than 0.932g / cm 3 It is more preferable to use the following linear low-density polyethylene.

[0032] When the rust-preventive film of this disclosure is composed of a single layer as shown in Figure 1, it contains a phenolic antioxidant along with the recycled polyethylene constituting the layer. Examples of phenolic antioxidants include octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and pentaerythritol tetrakis[3-(3,5-ditterlybutyl-4-hydroxyphenyl)propionate]. Commercially available phenolic antioxidants may also be used, for example, 3,3',3pha',.alpha Examples include '',5,5',5”-Hexa-tert-butyl-.alpha,.alpha',.alpha”-(mesitylene-2,4,6-triyl)tri-p-cresol (BASF IRGANOX 1330) and 3,9-Bis{2-「3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy」-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro「5.5」undecane (ADEKA ADEKA Stab AO-80).

[0033] Phenolic antioxidants can be incorporated into recycled polyethylene to form a rust-preventive film, or they can be added to used polyester during mechanical recycling when it is remelted. In other words, the phenolic antioxidant may already be contained in the recycled polyester.

[0034] The phenolic antioxidant is preferably included in a ratio of 500 to 5000 ppm relative to the recycled polyethylene, and more preferably in a ratio of 1000 to 4000 ppm. This does not exclude the inclusion of phenolic antioxidants used in the production of recycled polyethylene; recycled polyethylene may contain conventionally used antioxidants (phosphoric acid-based, sulfur-based, amine-based, etc.). Furthermore, as described later, if the rust-preventive film is multilayered, the volatile rust inhibitor is preferably included in the recycled polyethylene in the layer containing the volatile rust inhibitor at a ratio of 00 ppm, and more preferably in a ratio of 1000 to 4000 ppm.

[0035] Furthermore, if virgin polyethylene is included in addition to recycled polyethylene, a phenolic antioxidant may be used during the manufacture of the virgin polyethylene. In this case, the amount of phenolic antioxidant shall be the total amount of phenolic antioxidants contained in the recycled polyethylene and virgin polyethylene, as well as the phenolic antioxidants added during the manufacture of the rust-preventive film.

[0036] As a volatile rust inhibitor, among volatile rust inhibitors that volatilize at 40°C to 60°C and exhibit rust-preventive effects (for example, various ammonium salts of aliphatic or aromatic acids, nitrites of amines, carboxylates of amines, chromates of amines, esters of carboxylic acids, heterocyclic compounds and thioureas, mercapto groups, and heterocyclic compounds such as triazole rings, pyrrole rings, pyrazole rings, thiazole rings, and imidazole rings), carboxylic acid esters and heterocyclic aromatic compounds that can suppress the reduction of rust-preventive effect by phenolic antioxidants are used.

[0037] As a carboxylic acid ester-based rust inhibitor, fatty acid esters can be preferably used. Fatty acid esters with 6 to 20 carbon atoms in the fatty acid portion are preferred. 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. Specific 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, glycerin fatty acid esters, and more preferably glycerin tricaprylic acid esters. Among the above-mentioned 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 glycerin tricaprylic acid ester.

[0038] Examples of heterocyclic aromatic compounds include compounds having a triazole ring, pyrrole ring, pyrazole ring, thiazole ring, or imidazole ring, with particular preference for compounds having a triazole ring or being benzoate compounds. More specifically, examples of rust inhibitors having a triazole ring include benzotriazole (BTA) and tolyltriazole (TTA). Examples of benzoate compounds include monoethanolamine benzoate (MEA·BA), dicyclohexylammonium benzoate (DICHA·BA), and diisopropylammonium benzoate (DIPA·BA).

[0039] From the viewpoint of the release properties of the rust inhibitor and the extrusion film-forming properties of the resin, the amount of volatile corrosion inhibitor added is preferably 0.1% by mass or more and 30% by mass or less relative to the recycled polyethylene constituting the layer containing the volatile corrosion inhibitor, preferably 0.5% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 10% by mass or less. Furthermore, if the layer containing the volatile corrosion inhibitor contains recycled polyethylene and virgin polyethylene as resin components, it is preferably added at a rate of 0.1% by mass or more and 30% by mass or less relative to the total amount of recycled polyethylene and virgin polyethylene, preferably 0.5% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 10% by mass or less.

[0040] When the rust-preventive film of this disclosure is composed of a single layer as shown in Figure 1, the thickness of the rust-preventive film may be appropriately determined depending on the intended use, but from the viewpoint of the diffusivity of the volatile rust inhibitor, it is generally 50 μm or more, more preferably 60 μm or more, even more preferably 80 μm or more, and generally 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less.

[0041] Next, embodiments of the anti-corrosion film of the present disclosure that are multilayered will be described. As shown in Figures 2 and 3, the anti-corrosion film of the present disclosure may have a second layer in addition to a layer containing a volatile corrosion inhibitor (first layer), and may also have a third layer in addition to the second layer. The second layer and / or the third layer constitute the outermost layer when the anti-corrosion film is used as packaging for metal parts, etc. By having an outermost layer, the volatile corrosion inhibitor contained in the first layer can be prevented from diffusing into the atmosphere outside the anti-corrosion film. In addition, the resistance to punctures is improved compared to a single-layer film. Therefore, even when packaging metal machine parts that have protrusions, the anti-corrosion film of the present disclosure can prevent tearing by machine parts.

[0042] When the rust-preventive film is multilayered, the layer containing the volatile rust inhibitor (the first layer) may have the same configuration as the single layer described above. Furthermore, when it is multilayered, the first layer is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, from the viewpoint of the diffusion of the volatile rust inhibitor. From the viewpoint of film-forming properties and processability, it is preferably 60 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. The thickness of the rust inhibitor-containing layer is, for example, 10 to 30 μm.

[0043] If the second and / or third layer is the outermost layer, the resin component shall be primarily polyethylene having the same density as or greater than the polyethylene constituting the layer containing the volatile corrosion inhibitor (the first layer). For example, if the polyethylene constituting the first layer is low-density polyethylene or linear low-density polyethylene, the outermost layer may be made of low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, or high-density polyethylene.

[0044] The second layer, provided on the outer surface of the first layer, may be composed of recycled polyethylene and / or virgin polyethylene, but from the viewpoint of reducing environmental impact, it is preferable that it be composed of recycled polyethylene (especially mechanically recycled polyethylene), which is a mixture of various used polyethylenes (low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, and other polyethylenes) during recycling. However, considering film-forming properties and processability, it is preferable to use recycled polyethylene with an MFR of 0.1 g / 10 min to 30 g / 10 min.

[0045] The second layer may contain virgin polyethylene in addition to recycled polyethylene. By appropriately adding virgin polyethylene, film-forming properties and processability can be improved. When the intermediate layer contains recycled polyethylene and virgin polyethylene, the virgin polyethylene content is preferably between 0% and 50% by mass, and preferably between 15% and 35% by mass, relative to the total intermediate layer.

[0046] If the second layer contains virgin polyethylene, the amount of virgin polyethylene is preferably 0.860 g / cm³. 3 More than 0.932g / cm 3 The following low-density polyethylene, more preferably 0.900 g / cm³ 3 More than 0.932g / cm 3 The following low-density polyethylene, or preferably 0.860 g / cm³ 3 More than 0.932g / cm 3 The following linear low-density polyethylene, more preferably 0.900 g / cm³ 3 More than 0.932g / cm 3 The following is linear low-density polyethylene.

[0047] From the viewpoint of reducing environmental impact, the thickness of the second layer is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more. From the viewpoint of film-forming properties and processability, it is preferably 80 μm or less, more preferably 70 μm or less, and even more preferably 60 μm or less. The thickness of the second layer is, for example, 40 to 60 μm.

[0048] Furthermore, it is preferable that the second layer has a thickness of 2 to 4 times the thickness of the layer containing the volatile corrosion inhibitor (the first layer) described above. When using recycled polyethylene, the melting temperature during film formation needs to be slightly higher (around 200 to 210°C) than that of virgin polyethylene. When the first and second layers (and even the third layer) are formed using, for example, an inflation co-extrusion film formation method, the thickness of the intermediate layer is set to 2 to 4 times the thickness of the corrosion inhibitor-containing layer. This allows for sufficient heat to melt the recycled polyethylene during extrusion film formation while simultaneously allowing the surface of the first layer, which is located in the innermost layer, to be air-cooled. This suppresses thermal degradation and volatilization of the volatile corrosion inhibitor in the first layer. It is even more preferable that the second layer has a thickness of 2 to 3 times the thickness of the first layer.

[0049] When a third layer is added in addition to the second layer, it is preferable to use a high-density polyethylene for the third layer from the viewpoint of suppressing the diffusion of volatile corrosion inhibitors. However, from the viewpoint of film formation properties when forming the corrosion inhibitor film and suppression of curling of the resulting film, polyethylene should be selected so that the density difference between the polyethylene constituting the corrosion inhibitor-containing layer of the first layer and the polyethylene constituting the third layer is not large. From the viewpoint of suppressing the diffusion of volatile corrosion inhibitors and suppressing curling, it is preferable to use low-density polyethylene or linear low-density polyethylene that has the same density as or greater than the polyethylene constituting the corrosion inhibitor-containing layer.

[0050] Furthermore, either virgin polyethylene or recycled polyethylene may be used as the polyethylene constituting the third layer. From the viewpoint of reducing environmental impact, it is preferable to use recycled polyethylene for the third layer as well. However, as mentioned above, from the viewpoint of suppressing the diffusion of volatile corrosion inhibitors and suppressing curling, it is preferable to use virgin polyethylene (low-density polyethylene or linear low-density polyethylene) which has the same density as or greater than the polyethylene constituting the corrosion inhibitor-containing layer.

[0051] The thickness of the third layer is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, from the viewpoint of suppressing the diffusion of volatile rust inhibitors. From the viewpoint of film-forming properties and processability, it is preferably 60 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. The thickness of the rust inhibitor-containing layer is, for example, 10 to 30 μm.

[0052] Furthermore, when recycled polyethylene is used for the second and / or third layer, a phenolic antioxidant may be added during the production of the rust-preventive film in addition to the antioxidant contained in the recycled polyethylene during its production. The amount of phenolic antioxidant added is preferably 500 to 5000 ppm relative to the recycled polyethylene, and more preferably 1000 to 4000 ppm.

[0053] Even when the anti-corrosion film of this disclosure is multilayered, the total thickness may be appropriately adjusted depending on the application, and is generally 50 μm or more, more preferably 60 μm or more, even more preferably 80 μm or more, and generally 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less.

[0054] [Method for manufacturing rust-proof film] When the rust-preventive film of this disclosure is a single layer, it can be obtained by mixing recycled polyethylene, a volatile rust inhibitor, and an antioxidant, and then using methods such as inflation film formation with a circular die or extrusion film formation with a T die.

[0055] In the case of a multi-layered anti-corrosion film, it can be obtained by co-extruding a layer containing a volatile corrosion inhibitor (the first layer) with other layers (the second or third layer). For co-extrusion, known film-making methods such as the inflation co-extrusion method and the co-extrusion method can be employed. In particular, the inflation co-extrusion method allows for melt co-extrusion film formation at lower temperatures, such as 200°C or below, thus suppressing the thermal decomposition and volatilization (vaporization) of the volatile corrosion inhibitor during film formation.

[0056] When forming the film, each component may be mixed simultaneously, or a masterbatch may be prepared in advance by mixing recycled polyethylene with a volatile corrosion inhibitor or antioxidant, and the film may be formed by mixing the recycled polyethylene with the masterbatch. In particular, in order to improve the dispersibility of the volatile corrosion inhibitor, a masterbatch containing the volatile corrosion inhibitor may be used, and the film may be co-extruded using a blend of the masterbatch and recycled polyethylene. The proportion of volatile corrosion inhibitor in the masterbatch is not particularly limited, but the masterbatch and polyethylene of a predetermined density should be blended so that the proportion of volatile corrosion inhibitor in the corrosion inhibitor-containing layer falls within the range described above.

[0057] Furthermore, the rust-preventive film disclosed herein may have various additives added to one or more layers, to the extent that it does not impair its properties. Examples of additives include antioxidants, slip agents, plasticizers, ultraviolet stabilizers, color inhibitors, matting agents, deodorants, flame retardants, weather-resistant agents, antistatic agents, thread friction reducers, mold release agents, ion exchange agents, antiblocking agents, and coloring pigments.

[0058] The rust-preventive film disclosed herein can be used as a packaging material for packaging metal components such as machine parts. There are no particular restrictions on the shape or form of the packaging material; it can be in the form of a film to wrap the contents, or the rust-preventive film can be folded or overlapped and heat-sealed to form a bag. [Examples]

[0059] The laminates of the present disclosure will be described in more detail below with reference to examples, but the laminates of the present disclosure are not limited to the following examples.

[0060] [Example 1] A co-extruded film having a three-layer structure consisting of a first layer, a second layer, and a third layer was fabricated using a co-extrusion inflation film manufacturing machine. The first layer is made of recycled polyethylene (density 0.920 g / cm³). 3 A dry blend was used of recycled polyethylene and a masterbatch of the above recycled polyethylene and the volatile corrosion inhibitor in a ratio of 90:10 by mass, consisting of MFR 1.0g / 10min (Dow Chemical, XUS60922.01), a phenolic antioxidant (BASF Japan, Irganox1010) in an amount equivalent to 1500 ppm relative to the recycled polyethylene, and the above recycled polyethylene. The masterbatch of the volatile corrosion inhibitor was prepared by kneading ester compounds of pentanoic acid, hexanoic acid, heptanoic acid, and octanoic acid into the above polyethylene in an amount equivalent to 10% by mass. As the second layer, recycled polyethylene (density 0.920 g / cm³) 3 The following was used: MFR 1.0g / 10min (Dow Chemical Company, XUS60922.01) and a phenolic antioxidant (BASF Japan, Irganox1010) in an amount equivalent to 1500 ppm relative to recycled polyethylene. As the third layer, linear low-density polyethylene (density 0.931 g / cm³) 3 The MFR was 2.1g / 10min, using UZ3520 manufactured by Prime Polymer Co., Ltd. The thickness of each layer of the anti-corrosion film obtained as described above was 20 μm for the first layer, 50 μm for the second layer, and 10 μm for the third layer.

[0061] [Example 2] A rust-preventive film was obtained in the same manner as in Example 1, except that the carboxylic acid ester compound was replaced with benzotriazole, a heterocyclic aromatic compound, as the volatile rust inhibitor.

[0062] [Comparative Example 1] A rust-preventive film was obtained in the same manner as in Example 1, except that ethanolamine, an amine-based volatile rust inhibitor, was used instead of a carboxylic acid ester compound as the masterbatch containing the volatile rust inhibitor.

[0063] [Comparative Example 2] A rust-preventive film was obtained in the same manner as in Example 1, except that a phosphoric acid-based antioxidant (Irgafos168, manufactured by BASF Japan) was used instead of a phenol-based antioxidant as the antioxidant.

[0064] [Rust prevention evaluation] Each anti-corrosion film obtained as described above was cut to a size of 150mm x 200mm to be used as an evaluation sample. A degreased iron plate (gray cast iron, FC200, degreased, shape: 40mm x 60mm x 10mm) was covered with the film and stored in a constant temperature bath adjusted to 40°C and 90%RH for 20 days. After that, the appearance of the iron plate was evaluated according to the evaluation criteria below. ◎: No rust or discoloration, or only spot rust and slight discoloration. ○: Rust occurs in less than 10% of the surface area of ​​the iron plate. △: Rust occurs in areas of the iron plate surface that cover 10% to less than 50% of the total surface area. ×: Rust has occurred in more than 50% of the surface area of ​​the iron plate. The evaluation results are shown in Table 1 below.

[0065] Furthermore, the amount of reduction in each resin composition (recycled polyethylene, antioxidant, and volatile corrosion inhibitor) constituting the first layer of Example 1 and Comparative Example 1 was measured using a mass spectrometer (GCMS-QP2010, Shimadzu Corporation) to evaluate the amount of volatile corrosion inhibitor lost. Only the volatile corrosion inhibitor was measured and used as a blank. The measurement results are shown in Figure 4.

[0066] Furthermore, the amount of volatile corrosion inhibitor lost from each resin composition constituting the first layer in Example 1 and Comparative Example 2 was evaluated in the same manner as described above. The measurement results are shown in Figure 5.

[0067] [Table 1]

[0068] As is clear from the evaluation results in Table 1 and Figures 4-5, the rust-preventive film of this disclosure has excellent rust-preventive performance despite using recycled resin. [Explanation of symbols]

[0069] 1. Rust-proof film 10. The first layer 20. Second layer 30 The third layer

Claims

1. A rust-preventive film comprising at least recycled polyethylene, a volatile corrosion inhibitor, and an antioxidant, The volatile rust inhibitor is selected from carboxylic acid esters and heterocyclic aromatic compounds. A rust-preventive film in which the antioxidant is a phenolic antioxidant.

2. The rust-preventive film according to claim 1, wherein the volatile rust inhibitor is contained in a proportion of 2 to 10% by mass relative to recycled polyethylene.

3. The rust-preventive film according to claim 1, wherein the antioxidant is contained in a ratio of 500 to 5000 ppm relative to the recycled polyethylene.

4. The device comprises a first layer containing at least recycled polyethylene, a volatile corrosion inhibitor, and an antioxidant, and a second layer containing recycled polyethylene and / or virgin polyethylene. The rust-preventive film according to claim 1, wherein the first layer and the second layer are co-extruded.

5. The recycled polyethylene has a density of 0.860 g / cm³. 3 0.932g / cm or more 3 The rust-preventive film according to claim 1, wherein the polyethylene is as follows.

6. Density is 0.860 g / cm³ 3 0.932g / cm or more 3 The rust-preventive film according to claim 5, wherein the following polyethylene is at least one selected from low-density polyethylene and linear low-density polyethylene.

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