Multilayer rust preventive film

Abstract

The present invention addresses the problem of: preventing a metal film from being deteriorated with respect to properties required for use as a rust-preventive film even when the metal film is stored for a long period of time under a high temperature; and achieving rust prevention properties at the same levels as those achieved in normal use, in circumstances where the rust prevention properties are required under harsh environmental conditions or in situations where it is difficult to perform careful handling, and additionally in circumstances where rust prevention properties are required for a long period of time. As a solution, the present invention provides a multilayer rust preventive film which includes the resin layer 1 and the resin layer 2 described below.　Resin layer 1: a layer which contains calcium nitrite particles that have an average particle diameter of 50 μm or more and a high-density polyethylene that has a density of 0.945 g / cm3 or more Resin layer 2: a layer which contains a low-density polyethylene and / or a linear low-density polyethylene

Description

Laminated anti-rust film

[0001] The present invention relates to a laminated anticorrosive film.

[0002] As described in the examples of Patent Document 1, a laminated rust-preventive film having a resin layer made of low-density polyethylene containing sodium nitrite is known. The laminated rust-preventive film of this invention is capable of exhibiting rust-preventive effects regardless of the storage conditions after production until use. The examples are based on the premise that the laminated rust-preventive film is used in the state immediately after production.

[0003] Japanese Patent Application Laid-Open No. 2019-131267

[0004] By using a two-layer laminated sheet as a laminated rust-preventive film for storing metal products, etc., it is possible to achieve a longer-term rust-preventive effect. However, in recent years, there has been a growing demand for a film that does not lose its properties as a rust-preventive film even when stored at high temperatures for long periods of time, and that exhibits the same rust-preventive properties as under normal conditions in situations where rust prevention is required even in harsh environments or situations where careful handling is difficult, and where rust prevention is required for a long period of time. However, conventional rust-preventive films have not been able to exhibit sufficient rust-preventive properties in such situations.

[0005] The present inventors have conducted extensive research to solve the above problems, and have found that the problems can be solved by the following means, thereby completing the present invention: 1. A laminated rust-preventive film having the following resin layer 1 and resin layer 2. Resin layer 1: calcium nitrite particles having an average particle diameter of 50 μm or more and a density of 0.945 g / cm ３1. A laminated rust-preventive film according to 1, which has the following resin layer 3 on the side of said resin layer 2: Resin layer 3: A layer containing calcium nitrite particles having an average particle size of 50 μm or more, and low-density polyethylene and / or linear low-density polyethylene 3. A laminated rust-preventive film according to 1 or 2, in which resin layer 2 contains an amine / ammonium salt 4. A laminated rust-preventive film according to any one of 1 to 3, in which the thickness of resin layer 1 is 15 to 45 times the thickness of the laminated rust-preventive film taken as 100.

[0006] According to the laminated rust-preventive film containing calcium nitrite salt having a specific particle size, containers, sheet-like articles, and bags at least partially composed of this laminated rust-preventive film can maintain their rust-preventive effect for a longer period of time when they are used to store or package metal products, etc., that may be susceptible to rust. This allows for reliable prevention of rust for a longer period of time during transport, storage, etc. Furthermore, even when stored at high temperatures before use, the film provides excellent rust-preventive properties during use and exhibits sufficient rust-preventive properties even under harsh operating conditions. Specifically, the laminated rust-preventive film can perform well in VIA tests after fatigue testing and in airborne corrosion prevention.

[0007] The present invention relates to a laminated rust-preventive film, which may have a substrate layer. The present invention will be described below. In the present invention, the density of the resin was measured according to Method A of JIS K7112:1999. In this specification, calcium nitrite, potassium nitrite, and sodium nitrite may be referred to as Ca nitrite, K nitrite, and Na nitrite, respectively. Furthermore, resin layer 1, resin layer 2, and resin layer 3 in the present invention may each consist of a single layer or multiple layers.

[0008] (Laminated Rust-Preventive Film) The laminated rust-preventive film of the present invention is a laminated rust-preventive film having a resin layer 1 and a resin layer 2. However, a plurality of resin layers 1 may be provided, and a plurality of resin layers 2 may be provided. When resin layer 1 consists of two or more layers, the calcium nitrite and resin, etc. contained in each layer can be determined independently. It is necessary that each of these layers satisfy the requirements for the laminated rust-preventive film of the present invention. When resin layer 2 consists of two or more layers, the low-density polyethylene and / or linear low-density polyethylene, etc. contained in each layer can be determined independently. It is necessary that each of these layers satisfy the requirements for the laminated rust-preventive film of the present invention.

[0009] [Resin layer 1] Resin layer 1 contains calcium nitrite particles having an average particle diameter of 50 μm or more and a density of 0.945 g / cm ３ The resin layer 1 may be formed from a single layer, or a plurality of resin layers 1 may be laminated to form the resin layer 1 as a whole. When a plurality of resin layers 1 are laminated, each resin layer 1 independently has an average particle size and content of calcium nitrite particles contained therein, and a density of 0.945 g / cm. ３ The type of high-density polyethylene and the resin composition can be determined as described above. From the viewpoint of mechanical strength and processability, the melt flow rate (MFR) is preferably 1.0 g / 10 min or more, more preferably 3.0 g / 10 min or more, and even more preferably 4.0 g / 10 min or more. It is also preferably 10.0 g / 10 min or less, more preferably 8.0 g / 10 min or less, and even more preferably 7.0 g / 10 min or less. By setting the MFR within this range, the resin has an appropriate strength and a suitable viscosity during melt processing, which allows particulate calcium nitrite to be included in and coated with the resin, thereby preventing the rust inhibitor from falling off from the resin molded product.

[0010] (Calcium nitrite particles having an average particle diameter of 50 μm or more contained in resin layer 1) Resin layer 1 contains calcium nitrite particles having an average particle diameter of 50 μm or more. The content of the calcium nitrite particles is preferably 0.01 parts by weight or more, more preferably 0.10 parts by weight or more, even more preferably 0.50 parts by weight or more, and most preferably 1.00 parts by weight or more, per 100 parts by weight of resin layer 1. It is also preferably 10.00 parts by weight or less, more preferably 5.00 parts by weight or less, even more preferably 3.00 parts by weight or less, and most preferably 2.50 parts by weight or less. If it is less than 0.01 parts by weight, it is difficult to further improve rust prevention properties, and if it exceeds 10.00 parts by weight, molding processing becomes difficult. The average particle diameter of the calcium nitrite particles is 50 μm or more, preferably 55 μm or more, and more preferably 60 μm or more. The average particle diameter is preferably 150 μm or less, and more preferably 140 μm or less. When the average particle size is 50 μm or more, excellent effects are exhibited in the VIA test after the fatigue test. It is preferable not to contain potassium salt, sodium salt, or magnesium salt of nitrite, but these may be contained without limiting the average particle size as long as the effects of the present invention are not impaired. When these metal nitrite salts are contained, the content is preferably, for example, 0.01 part by weight or more and preferably 1.0 part by weight or less per 100 parts by weight of the resin layer. If the content exceeds 1.0 part by weight, molding becomes difficult.

[0011] The average particle diameter of the calcium nitrite particles is the value of the long diameter D50 of the calcium nitrite particles before being blended into the resin layer. ３ By using the above high-density polyethylene in combination, the decrease in the amount of calcium nitrite was suppressed even when stored in an atmosphere of 60°C for 288 hours, and the anti-rust effect was the same as that of a new product. In contrast, when calcium nitrite particles with a D50 of 50 μm or more were used, and the density was 0.945 g / cm ３ When calcium nitrite particles with a D50 of less than 50 μm were dispersed in polyethylene with a density of 0.945 g / cm, the amount of calcium nitrite decreased after 288 hours of storage in an atmosphere at 60°C.３ When dispersed in the above high density polyethylene, the amount of calcium nitrite decreased after storage in an atmosphere at 60° C. for 288 hours.

[0012] (Resin Constituting Resin Layer 1) The resin constituting the resin layer 1 is a resin having a density of 0.945 g / cm ３ It is necessary for the polyethylene to contain a high density polyethylene having a density of 0.945 g / cm or more. ３ The high-density polyethylene is not limited to the above, and any known polyethylene selected from the polyethylenes listed below in "Polyethylenes that can be used in Resin Layer 1 and Resin Layer 2" can be used. ３ When the density is 0.945 g / cm or more, excellent effects are exhibited in the VIA test after the fatigue test. ３ The content of the above high density polyethylene is more than 50 parts by weight, preferably 70 parts by weight or more, more preferably 90 parts by weight or more, and even more preferably 95 parts by weight or more. ３ By using the above high-density polyethylene, the effect of calcium nitrite as a rust inhibitor can be maintained for a long period of time during use. Other polyolefins such as polyethylene that can be used in combination may be contained as resins other than high-density polyethylene. Even when other polyolefins such as polyethylene that can be used in combination are contained, the density of the entire resin components constituting the resin layer 1 is 0.945 g / cm. ３ That's all. By combining calcium nitrite particles with the above average particle size, it is possible to suppress the thermal loss of calcium nitrite. Furthermore, by reducing the thickness of the resin layer 1 in the entire laminated rust-preventive film and combining this with the high deliquescent property of calcium nitrite, it is possible to increase the volatility of the rust inhibitor derived from calcium nitrite even in a high-humidity atmosphere. Density: 0.945 g / cm ３ Among the above high density polyethylenes, 0.948 g / cm ３ Preferably, it is 0.950 g / cm or more. ３ The above is more preferable.

[0013] [Resin Layer 2] (Resin Constituting Resin Layer 2) The resin constituting Resin Layer 2 may contain low-density polyethylene and / or linear low-density polyethylene. Here, the low-density polyethylene and / or linear low-density polyethylene has a density of 0.925 g / cm ３ The low-density polyethylene and / or linear low-density polyethylene is not limited, and known polyethylenes can be used from the polyethylenes described below in "Polyethylenes that can be used in Resin Layer 1 and Resin Layer 2." ３ When the density is 0.925 g / cm or less, excellent effects are exhibited in the VIA test after the fatigue test in combination with the resin layer 1. ３ The content of the low-density polyethylene and / or linear low-density polyethylene described below is more than 50 parts by weight. Preferably, it is 55 parts by weight or more, more preferably 60 parts by weight or more, and even more preferably 65 parts by weight or more. As a resin other than the low-density polyethylene and / or linear low-density polyethylene, a polyolefin such as other polyethylene that can be used in combination may be contained. Alternatively, it may not be contained. Even when a polyolefin such as other polyethylene that can be used in combination is contained, the density of the entire resin components constituting the resin layer 2 is 0.925 g / cm. ３ The following is preferred:

[0014] From the viewpoint of mechanical strength and processability, the melt flow rate (MFR) is preferably 0.5 g / 10 min or more, more preferably 0.8 g / 10 min or more, and even more preferably 1.0 g / 10 min or more. Also, it is preferably 6.0 g / 10 min or less, more preferably 4.0 g / 10 min or less, and even more preferably 3.0 g / 10 min or less. By setting it within this range, in combination with the resin layer 1, it has appropriate strength and a moderate viscosity during melt processing, resulting in good moldability. The density is 0.925 g / cm ３ Among the following low density polyethylenes and / or linear low density polyethylenes, 0.923 g / cm ３ The following is more preferred: 0.921 g / cm ３ The following are more preferred:

[0015] [Polyethylene that can be used in resin layer 1 and resin layer 2] The resin that constitutes resin layer 1 is polyethylene having a density of 0.945 g / cm ３ The above-mentioned high-density polyethylene and the low-density polyethylene and / or linear low-density polyethylene that are the resins constituting the resin layer 2 can be selected from the following polyethylene polymers in consideration of the requirements of the present invention. ３ By using the above high-density polyethylene in combination with specific calcium nitrite, sufficient rust prevention can be achieved even in a VIA test after a fatigue test. By using low-density polyethylene and / or linear low-density polyethylene in the resin layer 2, heat sealing can be performed smoothly when producing a bag-shaped product with the resin layer 2 on the inside.

[0016] As such polyethylene, one or more types selected from polyethylene-based polymers, that is, homopolymers of ethylene, or copolymers using ethylene and an olefin other than ethylene as a monomer, can be used. Examples of the olefin (olefin monomer) other than ethylene that constitutes this polyethylene-based polymer include 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-based polymers include ethylene-based polymers, propylene-based polymers, 1-butene-based polymers, 1-hexene-based polymers, and 4-methyl-1-pentene-based polymers.

[0017] These polyethylene polymers may be used alone or in combination of two or more. That is, the polyolefin polymer may be a mixture of various polymers. When a mixture is used, it is sufficient that the mixture as a whole has a predetermined density. Among the above, examples of the ethylene polymer 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 (L-LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). Specific examples of the polyethylene polymer include ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-pentene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, and ethylene-4-methyl-1-pentene copolymers. The ethylene units (structural units derived from ethylene) contained in the polyethylene polymer may account for more than 50% of the total number of structural units (usually 99.999% or less), but may account for, for example, 80 to 99.999%, or 90 to 99.995%, or even 99.0 to 99.990% of the total number of structural units.

[0018] [Other Resins That May Be Used in Resin Layer 1 and Resin Layer 2] As described above, in each of Resin Layer 1 and Resin Layer 2, in addition to the polyethylene-based polymer that is essential for Resin Layer 1 and Resin Layer 2, other polyethylenes may also be used in combination. Alternatively, other polyethylenes may not be used in combination. Such polyethylenes may be arbitrarily selected from those described above. Alternatively, resins other than polyethylene may be blended within a range that does not impair the effects of the present invention. Alternatively, other resins may not be blended.

[0019] The density of polyolefin resin is 0.880 to 0.945 g / cm from the viewpoint of processability. ３From the viewpoint of mechanical strength and processability, the melt flow rate (MFR) is preferably in the range of 1.0 to 10.0 g / 10 min, and by having an appropriate viscosity during melt processing, it becomes possible to include and coat particulate calcium nitrite in the resin, and it becomes possible to prevent the rust inhibitor from falling off from the resin molded product.

[0020] [Amine / Ammonium Salt] An amine / ammonium salt (amine salt and / or ammonium salt) can be blended into the resin layer 2 of the present invention. Examples of such amine / ammonium salts include amine / ammonium salts of carboxylic acids, amine / ammonium salts of carbonic acid, and nitrous acid, which are used as rust inhibitors. An amine / ammonium salt may also be blended into the resin layer 1 as needed. Alternatively, an amine / ammonium salt need not be blended. When an amine / ammonium salt is blended into the resin layer 2, the content of the amine / ammonium salt per 100 parts by weight of the resin layer 2 blended with the amine / ammonium salt is preferably 0.10 parts by weight or more, more preferably 0.20 parts by weight or more, and preferably 0.30 parts by weight or more. The content is preferably 10.0 parts by weight or less, more preferably 5.0 parts by weight or less, even more preferably 3.0 parts by weight or less, and most preferably 1.5 parts by weight or less. When an amine / ammonium salt is blended in the resin layer 2, the content of the amine / ammonium salt in 100 parts by weight of the entire laminated rust-proofing film (the entire film including the resin layer 3 when the resin layer 3 described below is used) is preferably 0.05 parts by weight or more, more preferably 0.10 parts by weight or more, and preferably 0.15 parts by weight or more, and is preferably 5.0 parts by weight or less, more preferably 3.0 parts by weight or less, even more preferably 2.0 parts by weight or less, and most preferably 1.0 part by weight or less.

[0021] (Amine Carboxylate) As the amine carboxylate, a salt obtained by bonding cyclohexylamine, diisopropylamine, or dicyclohexylamine as a salt to the same carboxylic acid as the carboxylic acid component constituting the ammonium carboxylate can be selected.

[0022] (Ammonium Carboxylate) The ammonium carboxylate may be either an aliphatic ammonium carboxylate or an aromatic ammonium carboxylate. Specific examples of the ammonium carboxylate include butyric acid, isobutyric acid, methacrylic acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, sorbic acid, oleic acid, oleic acid, isohexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, isoheptanoic acid, isooctanoic acid, 2-ethylhexanoic acid, isononanoic acid, isodecanoic acid, 2-propylheptanoic acid, isoundecanoic acid, and isododecanoic acid. ammonium salts of aliphatic carboxylic acids such as 2-butyloctanoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, and dodecanedioic acid; and ammonium salts of aromatic carboxylic acids such as benzoic acid, aminobenzoic acid, salicylic acid, p-tert-butylbenzoic acid, o-sulfobenzoic acid, 1-naphthoic acid, 2-naphthoic acid, phthalic acid, isophthalic acid, terephthalic acid, and cinnamic acid.

[0023] (Amine / ammonium salts of carbonic acid or nitrous acid) In the above-mentioned ammonium carboxylates and amine salts of carboxylic acids, those in which the carboxylic acid is replaced with carbonic acid or nitrous acid can be used. Among these, cyclohexylamine carbonate (CHC) is preferred.

[0024] The amine / ammonium salt is contained in resin layer 1 and / or resin layer 2 in particulate form. When the laminated rust-preventive film further includes other resin layers, the amine / ammonium salt may be contained in the other resin layers. Alternatively, the amine / ammonium salt need not be contained. The average particle size of the amine / ammonium salt is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more. It is also preferably 60 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. This average particle size is the D50 value of the major axis of the particles of the ammonium salt of carboxylic acid or the like contained in the resin layer. By containing an amine salt or ammonium salt of carboxylic acid or the like having this specific particle size and controlling the amount of rust-preventive gas generated, the rust-preventive effect can be stably maintained over a long period of time.

[0025] (Carboxylic Acid Metal Salt) The resin layer 1 and the resin layer 2 of the laminated rust-preventive film of the present invention may each independently contain a carboxylate metal salt. The carboxylate metal salt may be either an aliphatic carboxylate metal salt or an aromatic carboxylate metal salt. Examples of these carboxylate metal salts include isobutyric acid, methacrylic acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, sorbic acid, oleic acid, oleic acid, isohexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, isoheptanoic acid, isooctanoic acid, 2-ethylhexanoic acid, isononanoic acid, isodecanoic acid, 2-propylheptanoic acid, isoundecanoic acid, isododecanoic acid, 2-butyloctanoic acid, sucralose ... One or more of the following may be used: aliphatic carboxylic acids such as benzoic acid, aminobenzoic acid, salicylic acid, p-tert-butylbenzoic acid, o-sulfobenzoic acid, 1-naphthoic acid, 2-naphthoic acid, phthalic acid, isophthalic acid, terephthalic acid, and cinnamic acid; and metal salts such as sodium salts, potassium salts, calcium salts, and magnesium salts of aromatic carboxylic acids such as benzoic acid, aminobenzoic acid, salicylic acid, p-tert-butylbenzoic acid, o-sulfobenzoic acid, 1-naphthoic acid, 2-naphthoic acid, phthalic acid, isophthalic acid, terephthalic acid, and cinnamic acid.

[0026] When a metal carboxylate is contained in each of resin layer 1 and resin layer 2, the content of the metal carboxylate is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, per 100 parts by weight of the resin layer. If the content is less than 0.001 part by weight, it is difficult to achieve sufficient rust prevention, and if it exceeds 10 parts by weight, molding becomes difficult.

[0027] (Benzotriazole-Based Compounds and Tolyltriazole-Based Compounds) Resin layer 1 and resin layer 2 of the laminated rust-preventive film of the present invention may each independently contain a benzotriazole-based compound and / or a tolyltriazole-based compound. Among these, one or more compounds selected from benzotriazole, 4-methylbenzotriazole, 5-methylbenzotriazole, and the like may be used. Alternatively, they may not be contained. The content of these benzotriazole-based compounds and tolyltriazole-based compounds is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, per 100 parts by weight of the resin layer. If the content is less than 0.001 part by weight, it is difficult to further improve long-term rust prevention, and if it exceeds 10 parts by weight, molding processing becomes difficult.

[0028] Furthermore, within the scope of not impairing the effects of the present invention, known additives different from the above-mentioned additives, such as antiblocking agents (AB agents), lubricants, antioxidants, antistatic agents, ultraviolet absorbers, processability improvers, etc., which are added to resins, can be added independently to each of resin layers 1 and 2. Note that, according to the present invention, sufficient long-term rust prevention can be achieved even without blending an ionomer resin or a functional group-containing polyolefin resin into the laminate rust-preventive film for the purpose of retaining the rust inhibitor in the resin layer.

[0029] [Resin Layer 3] Resin layer 3 can be provided on the surface of resin layer 2 of the laminated rust-preventive film of the present invention. Resin layer 3 is a layer containing calcium nitrite particles having an average particle size of 50 μm or more and low-density polyethylene and / or linear low-density polyethylene. Resin layer 3 contains calcium nitrite particles having an average particle size of 50 μm or more that are used in resin layer 1 as a rust inhibitor. As the low-density polyethylene and / or linear low-density polyethylene that can be used in resin layer 3, it is preferable to use the low-density polyethylene and / or linear low-density polyethylene that can be used in resin layer 2. The calcium nitrite particles having an average particle size of 50 μm or more that are added to resin layer 3 can be selected from the range of calcium nitrite particles that can be contained in resin layer 1.

[0030] [Laminated Rust-Preventive Film] The laminated rust-preventive film of the present invention may have any of the following structures: a laminated rust-preventive film having a substrate layer on only one side thereof; a laminated rust-preventive film having a substrate layer on both sides thereof; or a laminated rust-preventive film laminated on both sides of the substrate layer. Furthermore, any of these laminated rust-preventive films may be laminated. The thickness of resin layer 1 is preferably 15% or more and 45% or less of the total thickness of the laminated rust-preventive film of the present invention, regardless of whether resin layer 3 is present or not. Similarly, resin layer 2 is preferably 55% or more and 85% or less. Furthermore, resin layer 1 is preferably 20 to 50 μm, and resin layer 2 is preferably 50 to 95 μm. If resin layer 3 is present, resin layer 3 is preferably 10 to 30 μm. The laminated rust-preventive film of the present invention is basically a laminate of resin layer 1 and resin layer 2. Furthermore, resin layer 1, resin layer 2, and resin layer 3 may be laminated in this order. Resin layer 3 is a layer made of low-density polyethylene and / or linear low-density polyethylene, containing calcium nitrite particles having the same average particle size range as the calcium nitrite particles contained in resin layer 1, with an average particle size and content independent of those of resin layer 1. In this case, resin layer 3 preferably has a thickness of 5% to 25% of the total thickness of the laminated rust-proofing film consisting of resin layers 1 to 3.

[0031] (Substrate Layer) A substrate layer can be provided on at least one side of the laminated rust-preventive film of the present invention. The substrate layer is provided for purposes such as imparting strength to the laminated rust-preventive film of the present invention, imparting gas barrier properties and water vapor barrier properties, and improving tactile feel and aesthetics. Materials constituting the substrate layer can be materials that do not impair the rust-preventive effect of the laminated rust-preventive film and preferably have excellent adhesion to the resin constituting the laminated rust-preventive film. Materials constituting the substrate layer can include resins that can be used in the laminated rust-preventive film described above, resins that have excellent adhesion to the laminated rust-preventive film, and in addition, woven fabrics, nonwoven fabrics, and paper. When a resin is used, various known additives can be contained in the resin layer. Furthermore, the resin layer can be either porous or non-porous. The substrate layer can be formed from such a resin simultaneously with the formation of the laminated rust-preventive film, or can be formed separately from the laminated rust-preventive film and then laminated by known means.

[0032] (Production and Use of Laminated Rust-Preventive Film) Laminated rust-preventive films are formed by known methods such as extrusion molding, inflation molding, vacuum molding, and pressure molding. Among these, inflation molding is preferred. Based on the laminated rust-preventive film, any shape, such as a film, sheet, bag, laminated sheet, cylinder, or box, can be obtained. Furthermore, when a substrate film is laminated on the laminated rust-preventive film, the laminated rust-preventive film may be used so that the surface facing the laminated rust-preventive film is positioned inside a container or packaging sheet, i.e., on the side of the item to be stored or packaged for rust protection. By incorporating calcium nitrite particles with this specific particle size, the amount of rust-preventive gas generated can be controlled, resulting in stable maintenance of rust-preventive effects over a long period of time. Furthermore, by employing multiple resin layers, moisture gradually penetrates from the outside air in contact with the surface of the resin layer 1 toward the interior, thereby gradually generating rust-preventive gas. Therefore, a high level of rust-preventive effect can be maintained stably over a long period of time, even without the addition of rust-preventive sustained-release agents such as carboxylic acid-modified polyolefin polymers, waxes, nonionic surfactants, or inorganic porous bodies. It is also possible to add rust-preventive slow-release agents such as carboxylic acid-modified polyolefin polymers, waxes, nonionic surfactants, inorganic porous bodies, etc. The target articles to be rust-prevented can be a wide range of articles such as cast iron.

[0033] The present invention will be explained in more detail with reference to the following examples and comparative examples. Note that the examples show one embodiment of the present invention, and the present invention is not limited thereto. The density and MFR of each resin constituting each resin layer in the table are as follows. The resin HDPE has a density of 0.951 g / cm ３ , MFR is 5.5 g / 10 min Resin HDPE2 has a density of 0.964 g / cm ３ , MFR is 5.2 g / 10 min Resin HDPE3 has a density of 0.938 g / cm ３ , MFR is 0.2 g / 10 min Resin LDPE has a density of 0.920 g / cm ３ , MFR is 2.0 g / 10 min Resin LLDPE has a density of 0.903 g / cm ３, MFR is 3.8 g / 10 min. CHC is cyclohexylamine carbonate.

[0034] The materials were hand-blended to prepare molding compounds for the laminated rust-preventive films of each Example and Comparative Example shown in the table. These compounds were then extruded into tubular laminated films using an inflation extrusion molding machine. Calcium nitrite (Ca nitrite), sodium nitrite (Na nitrite), and potassium nitrite (K nitrite) were commercially available and were obtained by pulverizing and classifying under specified conditions.

[0035] Test method for VIA after fatigue test (performed in accordance with MIL-STD-3010C 5.4.1) (Fatigue test) A laminated rust-preventive film measuring 8 inches in length and 2 inches in width was placed vertically in a beaker. This beaker was left to stand for 288 hours in a space at a temperature of 60°C and a humidity of 50%, in accordance with MIL-STD-3010C 5.4.1. After standing, two laminated rust-preventive films measuring 6 inches in length and 1 inch in width were obtained from one laminated rust-preventive film measuring 8 inches in length and 2 inches in width.

[0036] (VIA test method after fatigue test) An SAE1018 plate with a diameter of 15.9 mm and a height of 12.7 mm was prepared, and the surface of the SAE1018 plate was polished by rubbing it left and right with #240. Next, it was polished by rubbing it up and down with #400. The polished surface was washed with first-grade methanol and wiped with a professional wipe. The VIA test after the fatigue test was conducted in accordance with MIL-STD-3010C 5.4.1, a US military standard. Note that SAE1018 was used instead of SAE1010 in MIL-STD-3010C 5.4.1.

[0037] (Evaluation of the surface of the VIA test results after the fatigue test) Each test surface (a circular surface of the SAE1018 plate with a diameter of 15.9 mm) was inspected at 10x magnification. Each test surface was evaluated based on the number of corrosion spots found. Furthermore, each test surface was magnified 40x to check for the presence or absence of spots exceeding 300 μm in diameter. (Evaluation criteria) ◯: 3 or less spots and no spots exceeding 300 μm in diameter (compliant) △: 4 or more spots or spots exceeding 300 μm in diameter (non-compliant) ×: Rust present throughout (non-compliant)

[0038] [Space test] The following test specimens were hung with nylon fishing line in a frame measuring 100 mm length x 100 mm width x 150 mm height, and the frame was gusset-sealed with the prepared film. This test configuration was left for the specified period under the test environment described below, and then the state of rust on the surface was evaluated based on the rust prevention evaluation criteria described below.

[0039] (Test piece) Cast iron (JIS G 5501) Size: φ30 mm x 8 mm

[0040] (Test environment) 25°C, 70% RH: 4 hours 50°C, 95% RH: 4 hours Set transfer time: 2 hours, total 12 hours / 1 cycle Evaluation days: 7 days (14 cycles)

[0041] (Rust prevention evaluation criteria for space test) ◯: No rust or discoloration △: Rust spots or slight discoloration ×: Rust or discoloration occurred in less than 10% of the area of ​​the test piece

[0042]

[0043]

[0044] In each example, the results of the VIA test after the fatigue test were good. In contrast, in each comparative example, the results of the VIA test after the fatigue test were unsatisfactory. In examples 1 to 3, the results of the 7-day spatial test were fair. In contrast, the results of the 7-day spatial test for examples 4 to 19, in which an amine / ammonium salt was contained in the resin layer 2, were excellent. Comparative examples 1, 2, and 6 are examples in which sodium nitrite or potassium nitrite was contained in the resin layer 1. Although they share the common feature of being nitrite salts as opposed to calcium nitrite, when sodium salt or potassium salt was used, the results of the VIA test after the fatigue test were inferior to those of the examples. In particular, comparative examples 1 and 2, which have resin layers 2 without a rust inhibitor, also showed poor results in the spatial test. Comparative examples 3 to 5 are examples in which the average particle diameter of calcium nitrite contained in the resin layer 1 was less than 50 μm. In this case, too, the results of the VIA test after the fatigue test were poor. Comparative example 7 is an example in which the density of the high-density polyethylene was 0.938 g / cm ３This is an example where the density range of the present invention is not satisfied. In this case, the results of the VIA test after the fatigue test were insufficient. Comparative Example 8 is an example where resin layer 1 does not contain calcium nitrite, and resin layer 2 contains ammonium adipate as a rust inhibitor. Comparative Example 9 is an example where resin layer 2 contains calcium nitrite, and resin layer 1 contains ammonium adipate. In these cases, the results of the VIA test and the spatial test after the fatigue test were poor.

Claims

1. A laminated rust-preventive film having the following resin layer 1 and resin layer 2: Resin layer 1: calcium nitrite particles having an average particle diameter of 50 μm or more and a density of 0.945 g / cm ３ The above-mentioned layer containing high density polyethylene, Resin layer 2: a layer containing low density polyethylene and / or linear low density polyethylene.

2. A laminated rust-preventive film as described in claim 1, having the following resin layer 3 on the resin layer 2 side: Resin layer 3: A layer containing calcium nitrite particles having an average particle diameter of 50 μm or more, and low-density polyethylene and / or linear low-density polyethylene.

3. The laminated rust-preventive film according to claim 1 or 2, wherein the resin layer 2 contains an amine / ammonium salt.

4. The laminated rust-preventive film according to claim 1 or 2, wherein the thickness of the resin layer 1 is 15 to 45 when the thickness of the laminated rust-preventive film is taken as 100.

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