Oxygen-absorbing resin composition, molded article, multilayer structure and container

Abstract

To provide an oxygen-absorbing resin composition that can exhibit superior oxygen-absorbing capability and a high Young's modulus (resilience), and ensures superior adhesion to other layers when used in multilayer structures, and to provide a molded article, a multilayer structure and a container, each including the oxygen-absorbing resin composition.SOLUTION: An oxygen-absorbing resin composition comprises a polymethylpentene resin (A), a polyolefin resin (B) other than the polymethylpentene resin (A), and a deoxidizer composition (C). The mass ratio of the polymethylpentene resin (A) to the polyolefin resin (B) [(A) / (B)] is 1 / 99 or more and 65 / 35 or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an oxygen-absorbing resin composition, and a molded article, a multilayer structure, and a container each using the same. [Background technology]

[0002] Oxygen absorbers that remove oxygen have been used for the purpose of preventing oxidation of various products that are easily deteriorated by oxygen, such as food, medicine, and metal products. The form of this oxygen absorber that was developed early and is still widely used today is a granular or powdered oxygen absorber composition packed in a small bag. As an improvement over this, a film or sheet form in which the oxygen absorber composition is fixed has been considered as a safe oxygen absorber that is easier to handle, has a wide range of applications, and is free from problems such as accidental ingestion. Such a film or sheet-like oxygen absorber can be used, for example, as a packaging container or packaging bag, and the packaging container or packaging bag itself can be provided with oxygen absorbing properties.

[0003] In general, in order to form the oxygen absorbing composition into a film or sheet, a method is conveniently used in which a granular or powdery oxygen absorbing composition is compounded using a thermoplastic resin as a matrix component. However, if this composite film or sheet is used as is in a container or the like, it will absorb oxygen from both sides, i.e., from both the inside and outside of the container, making it impossible to efficiently remove oxygen from inside the container. For this reason, in practice, this composite film or sheet is generally used in a configuration (multilayer configuration) in which an oxygen absorbing layer is used and a layer (outer layer) having gas barrier properties is arranged on one side of the oxygen absorbing layer (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-72941 Summary of the Invention [Problem to be solved by the invention]

[0005] In films or sheets having such oxygen absorbing properties, a relatively soft thermoplastic resin has usually been used as the matrix from the standpoint of ease of molding and prevention of protrusion of oxygen absorbing agent composition particles, but this sometimes results in a lack of stiffness as a film or sheet. Therefore, from the viewpoint of improving the handling properties and moldability of the film or sheet, a film or sheet with stiffness has been demanded. Furthermore, in situations where such films or sheets are used in the above-mentioned multi-layer configurations, there has been a demand for films or sheets that have good adhesion to other layers.

[0006] Therefore, an object of the present invention is to provide an oxygen-absorbing resin composition that can exhibit excellent oxygen-absorbing performance and a high Young's modulus (has firmness) and, when used in a multilayer structure, has good adhesion to other layers (e.g., adhesive layers), as well as a molded article, a multilayer structure, and a container using the same. [Means for solving the problem]

[0007] That is, the gist of the present invention is as follows. [1] An oxygen-absorbing resin composition comprising a polymethylpentene resin (A), a polyolefin resin (B) other than the polymethylpentene resin (A), and an oxygen scavenger composition (C), The oxygen-absorbing resin composition, wherein a mass ratio of the polymethylpentene resin (A) to the polyolefin resin (B) [(A) / (B)] is 1 / 99 or more and 65 / 35 or less. [2] The oxygen-absorbing resin composition according to the above [1], wherein the oxygen scavenger composition (C) contains iron powder as a main component. [3] The oxygen-absorbing resin composition according to the above [1] or [2], wherein the content of the oxygen scavenger composition (C) is 10% by mass or more and 85% by mass or less. [4] The oxygen-absorbing resin composition according to any one of [1] to [3] above, wherein the polyolefin resin (B) is at least one selected from the group consisting of polyethylene, polypropylene, polybutene, polybutadiene, and ethylene-propylene copolymer. [5] A molded article comprising the oxygen-absorbing resin composition according to any one of [1] to [4] above. [6] The molded article according to [5] above, wherein the molded article is a film or a sheet. [7] A multilayer structure comprising the film or sheet which is the molded article according to [6] above. [8] A multilayer structure having a multilayer structure in which a gas barrier layer, an adhesive layer, and an oxygen absorption layer are laminated in this order, The multilayer structure according to [7] above, wherein the oxygen absorption layer is composed of the film or sheet which is the molded article according to [6] above. [9] The multilayer structure according to [7] or [8] above, wherein the multilayer structure is a multilayer film or a multilayer sheet.

[10] A container comprising the multilayer structure according to any one of [7] to [9] above.

Advantages of the Invention

[0008] According to the present invention, there can be provided an oxygen-absorbing resin composition capable of exhibiting excellent oxygen absorption performance and a high Young's modulus (rigidity), and having good adhesion to other layers (for example, an adhesive layer) when used in a multilayer configuration, as well as a molded article, a multilayer structure, and a container using the same.

Embodiments for Carrying Out the Invention

[0009] Embodiments of the oxygen-absorbing resin composition according to the present invention, as well as a molded article, a multilayer structure, and a container using the same, will be described in detail below. In this specification, the term "A to B" regarding the description of numerical values means "A or more and B or less" (when A < B) or "A or less and B or more" (when A > B). Further, in the present invention, a combination of preferred embodiments is a more preferred embodiment.

[0010] [Oxygen-absorbing resin composition] The oxygen-absorbing resin composition of the present invention comprises a polymethylpentene resin (A), a polyolefin resin (B) other than the polymethylpentene resin (A), and an oxygen scavenger composition (C), and the mass ratio of the polymethylpentene resin (A) to the polyolefin resin (B) [(A) / (B)] is 1 / 99 or more and 65 / 35 or less.

[0011] By having the above-mentioned configuration, the oxygen-absorbing resin composition of the present invention can exhibit excellent oxygen-absorbing performance and a high Young's modulus (stiffness), and when used in a multi-layer configuration, it has good adhesion to other layers (e.g., adhesive layers). The reason why the oxygen-absorbing resin composition of the present invention exhibits the above-mentioned effects is not clear, but one possible reason is as follows.

[0012] Conventionally, polyolefin resins such as polyethylene have been widely used as thermoplastic resins for the matrix component because they have the following advantages: (1) excellent processability as a resin; (2) ability to disperse granular or powdery oxygen absorbing composition relatively uniformly as a matrix component; (3) appropriate oxygen permeability; (4) excellent compatibility with other resins; and (5) appropriate flexibility to prevent protrusion of oxygen absorbing composition particles when molded into a film or sheet. However, when, for example, a polyethylene resin or the like is used as the thermoplastic resin, there is a problem that the resulting film or sheet has a low Young's modulus and lacks stiffness. Therefore, the present inventors focused on polymethylpentene resin (A) from the viewpoint of solving the above-mentioned problems, and discovered that by blending polymethylpentene resin (A) with polyolefin resin (B) other than polymethylpentene resin (A), a film or sheet having excellent oxygen absorption performance and good stiffness can be obtained. On the other hand, the polymethylpentene resin (A) tends to have poor compatibility with other resins, and as the content of the polymethylpentene resin (A) in the oxygen-absorbing resin composition increases, problems such as (i) difficulty in producing a uniform oxygen-absorbing resin composition and (ii) reduced adhesion to other layers (e.g., adhesive layers) occur when the composition is molded into a film or sheet and used in a multilayer configuration. Therefore, the present inventors conducted further studies and found that by preparing an oxygen-absorbing resin composition containing a polymethylpentene resin (A) and a polyolefin resin (B) in a specific ratio, it is possible to obtain films and sheets that exhibit excellent oxygen absorption performance and a high Young's modulus (stiffness), and that, when used in a multi-layer configuration, exhibit good adhesion to other layers (e.g., adhesive layers), thereby completing the present invention.

[0013] Hereinafter, the oxygen absorbing resin composition according to this embodiment will be described in detail.

[0014] <Polymethylpentene resin (A)> The polymethylpentene resin (A) is a thermoplastic resin, and functions as a matrix component of the oxygen-absorbing resin composition. As the polymethylpentene resin (A) used in the present invention, for example, a polymer obtained by using one selected from the group consisting of 4-methyl-1-pentene and 3-methyl-1-pentene as a polymer component, or a copolymer obtained by using these methylpentenes as a copolymer component can be preferably used. Among them, 4-methyl-1-pentene (co)polymer is preferred from the viewpoint of availability.

[0015] The (co)polymer is obtained by using one or more olefins selected from the group consisting of 4-methyl-1-pentene and 3-methyl-1-pentene as a (co)polymer component. Examples of this specific olefin (co)polymer include homopolymers of 4-methyl-1-pentene or 3-methyl-1-pentene, or copolymers thereof, and further copolymers with other copolymerizable monomers, such as ethylene or α-olefins having 3 to 20 carbon atoms, styrene, acrylonitrile, vinyl chloride, vinyl acetate, acrylic acid esters, methacrylic acid esters, etc. Among the other copolymerizable monomers, α-olefins having 7 to 20 carbon atoms are preferred, and one or more selected from the group consisting of 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene are particularly preferred. Of the constituent units of the (co)polymer, the total amount of constituent units derived from 4-methyl-1-pentene or 3-methyl-1-pentene is preferably 50 to 100 mol %, more preferably 80 to 100 mol %.

[0016] The melt flow rate (MFR) of the 4-methyl-1-pentene (co)polymer preferably used in the present invention, measured in accordance with ASTM D1238 under conditions of a load of 5 kg and a temperature of 260° C., is determined in various ways depending on the application, but is usually in the range of 1 to 50 g / 10 min, preferably 2 to 40 g / 10 min, and more preferably 5 to 30 g / 10 min. When the melt flow rate of the 4-methyl-1-pentene (co)polymer is within the above range, the appearance and film formability of the obtained film are good. The melting point of the 4-methyl-1-pentene (co)polymer preferably used in the present invention is, for example, in the range of 100 to 250°C, preferably 150 to 240°C, and more preferably 200 to 240°C.

[0017] Commercially available examples of the polymethylpentene resin (A) used in the present invention include the TPX (registered trademark) series manufactured by Mitsui Chemicals, Inc.

[0018] The content of the polymethylpentene resin (A) in the oxygen-absorbing resin composition is, for example, 0.15 mass% or more and 60 mass% or less, preferably 0.5 mass% or more and 58.5 mass% or less, more preferably 3 mass% or more and 50 mass% or less, and even more preferably 3 mass% or more and 45 mass% or less.

[0019] <Polyolefin resin (B)> The polyolefin resin (B) used in the present invention is a polyolefin resin other than the above polymethylpentene resin (A). The polyolefin resin (B) is a thermoplastic resin, and functions as a matrix component of the oxygen-absorbing resin composition. Examples of the polyolefin resin (B) used in the present invention include polyolefins such as polyethylene, polypropylene, polybutene, polybutadiene, ethylene-propylene random copolymer, and ethylene-propylene block copolymer; polyolefin copolymers such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, and ethylene-methacrylic acid ester copolymer; and graft polymers of the above polyolefins or the above polyolefin copolymer with silicone resin. Among them, the polyolefin resin (B) is preferably one or more selected from the group consisting of polyethylene, polypropylene, polybutene, polybutadiene, and ethylene-propylene copolymer, more preferably one or more selected from the group consisting of polyethylene, polypropylene, and ethylene-propylene copolymer, even more preferably one or more selected from the group consisting of polyethylene and polypropylene, and even more preferably polyethylene. Among the polyethylenes, low-density polyethylene is preferred from the viewpoint of gas permeability, and linear low-density polyethylene is more preferred. The polyolefin resin (B) may contain the above components either alone or in combination of two or more.

[0020] The content of the polyolefin resin (B) in the oxygen-absorbing resin composition is, for example, 5 mass% or more and 89 mass% or less, preferably 7 mass% or more and 85.5 mass% or less, more preferably 20 mass% or more and 75 mass% or less, and even more preferably 23 mass% or more and 70 mass% or less.

[0021] The total content of the polymethylpentene resin (A) and the polyolefin resin (B) in the oxygen absorbing resin composition is, for example, from 10% by mass to 90% by mass, and preferably from 15% by mass to 90% by mass.

[0022] The mass ratio [(A) / (B)] of the polymethylpentene resin (A) to the polyolefin resin (B) in the oxygen-absorbing resin composition is from 1 / 99 to 65 / 35. By being within the above range, an oxygen-absorbing resin composition can be obtained that exhibits excellent oxygen-absorbing performance and a high Young's modulus (stiffness) and has good adhesion to other layers when used in a multi-layer structure. In particular, an oxygen-absorbing resin composition having a mass ratio [(A) / (B)] of less than 1 / 99 has a low Young's modulus and lacks stiffness. Therefore, from the viewpoint of obtaining an oxygen-absorbing resin composition having a high Young's modulus, the mass ratio [(A) / (B)] is 1 / 99 or more, preferably 5 / 95 or more, more preferably 10 / 90 or more, even more preferably 20 / 80 or more, still more preferably 25 / 75 or more, still more preferably 30 / 70 or more, and still more preferably 40 / 60 or more. In particular, the mass ratio [(A) / (B)] of the oxygen-absorbing resin composition exceeds 65 / 35, and the adhesion to other layers is deteriorated. Therefore, from the viewpoint of obtaining an oxygen-absorbing resin composition having good adhesion to other layers, the mass ratio [(A) / (B)] is 65 / 35 or less, preferably 60 / 40 or less, and more preferably 55 / 45 or less. In addition, from the viewpoint of further increasing the adhesion to other layers in the oxygen-absorbing resin composition, the mass ratio [(A) / (B)] is preferably 1 / 99 or more, and more preferably 5 / 95 or more. In the oxygen-absorbing resin composition of the present invention, particularly from the viewpoint of improving the Young's modulus and adhesion to other layers, the mass ratio [(A) / (B)] is preferably 5 / 95 or more and 65 / 35 or less, more preferably 10 / 90 or more and 65 / 35 or less, even more preferably 20 / 80 or more and 65 / 35 or less, still more preferably 25 / 75 or more and 60 / 40 or less, still more preferably 30 / 70 or more and 60 / 40 or less, and still more preferably 40 / 60 or more and 55 / 45 or less. In addition, in the oxygen-absorbing resin composition of the present invention, particularly from the viewpoint of improving the oxygen-absorbing performance, the mass ratio [(A) / (B)] is preferably 5 / 95 or more and 65 / 35 or less, more preferably 10 / 90 or more and 55 / 45 or less, even more preferably 25 / 75 or more and 55 / 45 or less, and still more preferably 25 / 75 or more and 50 / 50 or less.

[0023] <Oxygen Absorber Composition (C)> The oxygen scavenger composition (C) is used in the form of granules or powder, and is a component that exhibits oxygen absorbing performance by dispersing in the resin matrix of the polymethylpentene resin (A) and the polyolefin resin (B).

[0024] The oxygen scavenger composition (C) is not particularly limited, and a known oxygen scavenger composition can be used. For example, oxygen scavenger compositions containing metal powder such as iron powder, reducing inorganic substances such as iron compounds, reducing organic substances such as polyhydric phenols, polyhydric alcohols, ascorbic acid or its salts, or metal complexes as the main agent for oxygen absorption reaction can be mentioned. Among these, from the viewpoint of oxygen absorption performance, oxygen scavenger compositions containing iron powder as the main component are preferred, and in particular oxygen scavenger compositions consisting of iron powder and metal halide are more preferred, and oxygen scavenger compositions in which metal halide is attached to iron powder are even more preferred. When the oxygen absorbing composition contains iron powder as a main component, the content of the iron powder in the oxygen absorbing composition is, for example, 80% by mass or more, preferably 85% by mass or more, more preferably 86% by mass or more, and for example, 100% by mass or less, preferably 99% by mass or less. Specifically, the content of the iron powder in the oxygen absorbing composition is, for example, 80% by mass or more and 100% by mass or less, preferably 85% by mass or more and 100% by mass or less, more preferably 86% by mass or more and 99% by mass or less.

[0025] The iron powder used in the oxygen scavenger composition is not particularly limited as long as it can be dispersed in a resin and can cause an oxygen scavenging reaction, and any iron powder that is usually used in oxygen scavenger compositions can be used. The iron powder is preferably one in which the surface of iron (zero-valent metallic iron) is exposed, but may also have a very thin oxide film like a normal metal surface, as long as it does not impair the effects of the present invention. Specific examples of the iron powder that can be used include reduced iron powder, sponge iron powder, sprayed iron powder, ground iron powder, electrolytic iron powder, and pulverized iron. In addition, iron powder with a low content of oxygen and silicon as impurities is preferred, and iron powder with a metallic iron content of 95% by mass or more is particularly preferred.

[0026] The average particle size of the iron powder is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 10 to 200 μm, and even more preferably 20 to 100 μm. The maximum particle size of the iron powder is preferably 500 μm or less, more preferably 400 μm or less, even more preferably 50 to 350 μm, and even more preferably 50 to 300 μm. From the viewpoint of obtaining a molded product with good appearance, the smaller the particle size of the iron powder, the smoother the oxygen absorbing layer can be formed, and therefore it is preferable. However, from the viewpoint of cost, the particle size of the iron powder may be somewhat larger as long as it does not significantly affect the appearance of the molded product. The maximum particle size and average particle size of the iron powder are measured by the method described in the Examples.

[0027] The oxygen scavenger composition (C) may contain components other than the main component as required. Specifically, when the oxygen scavenger composition (C) contains iron powder as a main component, it preferably contains, for example, a metal halide.

[0028] Metal halides act catalytically on the oxygen absorption reaction of metallic iron. Preferable specific examples of metals include at least one selected from the group consisting of alkali metals, alkaline earth metals, copper, zinc, aluminum, tin, iron, cobalt, and nickel. In particular, at least one selected from the group consisting of lithium, potassium, sodium, magnesium, calcium, barium, and iron is preferred. Preferable specific examples of halides include chlorides, bromides, and iodides, with chlorides being particularly preferred. The content of the metal halide in the oxygen scavenger composition is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of iron powder. It is preferable that substantially all of the metal halide adheres to the iron powder and there is almost no free metal halide in the oxygen scavenger composition, and when the metal halide acts effectively, 0.1% to 5 parts by mass is sufficient. It is also preferable that the metal halide be made into an aqueous solution and then coated on the iron powder.

[0029] In the present invention, an iron powder composition having a surface coated with a metal halide can be preferably used as the oxygen scavenger composition. The iron powder composition can be prepared by mixing iron powder with an aqueous metal halide solution, and then drying the mixture to remove moisture. The metal halide is preferably added in a manner that does not easily separate from the iron powder. For example, preferred methods include pulverizing and mixing using a ball mill, speed mill, or the like to embed metal halide fine particles in recesses on the iron powder surface, using a binder to attach metal halide fine particles to the iron powder surface, and mixing an aqueous metal halide solution with iron powder and drying to attach metal halide fine particles to the metallic iron surface.

[0030] The content of the oxygen scavenger composition (C) in the oxygen absorbing resin composition is preferably 10% by mass or more and 85% by mass or less, more preferably 20% by mass or more and 60% by mass or less, and even more preferably 20% by mass or more and 50% by mass or less. When the content of the oxygen scavenger composition (C) is within the above range, the oxygen absorbing performance is improved and the molding processability is also good.

[0031] <Other ingredients (D)> The oxygen-absorbing resin composition may contain a component (D) other than the above components (A) to (C). Examples of the other component (D) include a thermoplastic resin (d) other than the above components (A) and (B) and various additives. Examples of the thermoplastic resin (d) include polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; ionomers; and elastomers. Examples of additives include antifoaming agents such as calcium oxide, lubricants such as zinc stearate and calcium stearate, antioxidants such as phenols or phosphorus-based agents, colorants such as organic or inorganic dyes or pigments such as titanium oxide, dispersants such as silanes or titanates, water absorbents such as polyacrylic acid, fillers such as silica or clay, and gas adsorbents such as zeolite or activated carbon.

[0032] When the oxygen-absorbing resin composition contains a thermoplastic resin (d) other than the above-mentioned components (A) and (B), the mass ratio of the thermoplastic resin (d) to the total content of the components (A) and (B) in the oxygen-absorbing resin composition [(d) / (A)+(B)] is, for example, 0.5 / 99.5 or less, preferably 0.1 / 99.9 or less. In addition, it is preferable that the oxygen-absorbing resin composition does not contain a thermoplastic resin (d) other than the above-mentioned components (A) and (B).

[0033] Furthermore, when the oxygen absorbing resin composition contains an additive, the content of the additive in the oxygen absorbing resin composition is, for example, 5 mass % or less.

[0034] <Manufacturing method> The method for producing the oxygen absorbing resin composition of the present invention is not particularly limited, but the following preferred examples can be mentioned. The oxygen-absorbing resin composition can be obtained by kneading a polymethylpentene resin (A), a polyolefin resin (B), and an oxygen scavenger composition (C), and further kneading a thermoplastic resin (d) and / or additives as necessary, thereby uniformly dispersing the oxygen scavenger composition in the resin. From the viewpoint of obtaining a uniform oxygen-absorbing resin composition, it is preferable to first knead the polymethylpentene resin (A) and the polyolefin resin (B), and, if necessary, the thermoplastic resin (d) in advance to prepare a resin mixture. When an additive is added, from the viewpoint of uniformly dispersing the additive, it is preferable to first knead the additive into the resin mixture to prepare an additive-containing resin composition, and then knead the oxygen scavenger composition, the resin mixture, and the additive-containing resin composition to prepare the oxygen-absorbing resin composition.

[0035] [Molded body] The molded article of the present invention is made of the oxygen-absorbing resin composition of the present invention. Such a molded article can exhibit excellent oxygen-absorbing performance and a high Young's modulus (stiffness), and when used in a multi-layer structure, has good adhesion to other layers.

[0036] The present molded article is not particularly limited as long as it is a molded product of the oxygen-absorbing resin composition of the present invention, but is preferably, for example, a film or sheet. In this specification, based on the "Packaging Terminology" standard of JIS Z0108:2012, a membrane-like molded product with a thickness of less than 250 μm is referred to as a "film," and a plate-like molded product with a thickness of 250 μm or more is referred to as a "sheet."

[0037] The thickness and shape of the molded article are not particularly limited, but when the molded article is a film, the thickness is, for example, 10 μm or more and less than 250 μm, preferably 10 μm or more and 200 μm or less, more preferably 50 μm or more and 200 μm or less, and when the molded article is a sheet, the thickness is, for example, 250 μm or more and 1000 μm or less, preferably 300 μm or more and 600 μm or less. The thickness of the molded article is preferably selected appropriately depending on the application.

[0038] The above molded body can be produced by a known method. Specifically, when the molded product is a film or sheet, (1) the oxygen-absorbing resin composition may be melt-kneaded in an extruder, then extruded through a strand die, cooled, pelletized in a pelletizer, and the pellets of the oxygen-absorbing resin composition are pressed to obtain a film or sheet, or (2) the oxygen-absorbing resin composition may be melt-kneaded in an extruder, then formed into a film from a T-die to obtain a film or sheet.

[0039] [Multilayer structure] The multilayer structure of the present invention includes a film or sheet which is the molded article of the present invention. Such a multilayer structure has excellent oxygen absorption performance and stiffness, and when used in a multilayer configuration, has good adhesion to other layers. The configuration of the multilayer structure is not particularly limited, but it is preferable that the multilayer structure has, for example, a multilayer structure in which a gas barrier layer, an adhesive layer and an oxygen absorbing layer are laminated in this order.

[0040] <Gas barrier layer> The gas barrier layer plays a role in blocking oxygen entering from the outside. The gas barrier layer may be one layer or two or more layers in the multilayer structure depending on the purpose. By providing two or more layers, the intrusion of oxygen from the outside can be more efficiently suppressed. The gas barrier layer is preferably a layer containing one or more selected from the group consisting of an inorganic vapor deposition film, a metal thin film, or a gas barrier resin such as an ethylene-vinyl alcohol copolymer or a polyamide resin, and from the viewpoint of gas barrier properties, an inorganic vapor deposition film is more preferable.

[0041] The thickness of the gas barrier layer varies depending on the constituent material, but when it is, for example, an inorganic vapor deposition film, it is preferably 0.01 to 100 μm, more preferably 0.5 to 50 μm, and even more preferably 1 to 30 μm. The gas barrier layer may be made of one type of material or may be made of multiple materials. When made of multiple materials, they may be used in a laminated state, and by using them in a laminated state, a higher barrier effect can be exhibited.

[0042] <Adhesive layer> The adhesive layer contains an adhesive resin as a main component. The adhesive resin is not particularly limited, and known adhesive thermoplastic resins can be used. For example, acid-modified polyolefins obtained by modifying olefin resins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and maleic anhydride, polyester resins, and polyisocyanate resins can be used. These may be used alone or in combination of two or more.

[0043] <Oxygen absorbing layer> The oxygen absorbing layer is made of a film or sheet which is the molded article of the present invention. That is, the oxygen absorbing layer is made of an oxygen absorbing resin composition which contains a polymethylpentene resin (A), a polyolefin resin (B) other than the polymethylpentene resin (A), and an oxygen scavenger composition (C), and the mass ratio of the polymethylpentene resin (A) to the polyolefin resin (B) [(A) / (B)] is 1 / 99 or more and 65 / 35 or less. Therefore, the oxygen absorbing layer preferably has each component and each ratio described in the section [Oxygen absorbing resin composition] above.

[0044] The suitable thickness of the oxygen absorbing layer is the same as the thickness when the molded article is a film or sheet. When the molded article is a film, the thickness is, for example, 10 μm or more and less than 250 μm, preferably 10 μm or more and 200 μm or less, more preferably 50 μm or more and 200 μm or less, and when the molded article is a sheet, the thickness is, for example, 250 μm or more and 1000 μm or less, preferably 300 μm or more and 600 μm or less. When the thickness of the oxygen absorbing layer is within the above range, the oxygen absorbing performance is excellent, and the cost efficiency and processability are good.

[0045] <Other layers> Furthermore, the multilayer structure may have layers other than the gas barrier layer, adhesive layer, and oxygen absorbing layer, if necessary. Examples of the other layers include a surface substrate layer, an oxygen permeable layer, and a sealant layer.

[0046] The surface substrate layer is a layer disposed on the gas barrier layer side, and serves as a protective layer for the gas barrier layer and also serves to improve the design and strength of the present multilayer laminate. The oxygen permeable layer is a layer that is placed on the oxygen absorbing layer side, and serves as an isolating layer to prevent items stored in the container from coming into direct contact with the oxygen absorbing layer, while also serving to quickly and efficiently allow oxygen within the container to pass through so that the oxygen absorbing layer can fully exert its oxygen absorption function. The sealant layer is a layer disposed on the oxygen-absorbing layer side, and serves as the innermost layer for heat sealing when the multilayer structure of the present invention is used as, for example, a bag-shaped packaging material. The oxygen-permeable layer may also serve as the sealant layer. The other layers are not particularly limited, and known layers can be used for each layer.

[0047] The multilayer structure of the present invention is not particularly limited as long as it contains a film or sheet which is the molded article of the present invention, but is preferably a multilayer film or multilayer sheet, and more preferably a multilayer film. In this specification, based on the "Packaging Terminology" standard of JIS Z0108:2012, a film-like multilayer structure having a thickness of less than 250 μm is referred to as a "multilayer film," and a plate-like multilayer structure having a thickness of 250 μm or more is referred to as a "multilayer sheet."

[0048] Furthermore, the thickness of the multilayer structure is not particularly limited, but when the multilayer structure is a multilayer film, the thickness is, for example, 20 μm or more and less than 250 μm, preferably 50 μm or more and less than 250 μm, and more preferably 100 μm or more and 220 μm or less, and when the multilayer structure is a multilayer sheet, the thickness is, for example, 250 μm or more and 1000 μm or less, and preferably 300 μm or more and 600 μm or less.

[0049] The multilayer structure can be prepared by a known method. Specifically, the above layers can be laminated by appropriately combining known methods such as co-extrusion, various lamination methods, and various coating methods depending on the properties of the materials of each layer, the processing purpose, the processing step, etc. Specifically, there are (1) a method in which a film or sheet corresponding to each layer of the gas barrier layer and the oxygen absorbing layer is produced or prepared in advance, an adhesive obtained by dissolving an adhesive resin in a solvent such as ethyl acetate is applied to at least one layer, and then the two layers are dry laminated with a laminator to obtain a multilayer structure having a layer configuration in which the gas barrier layer, the adhesive layer, and the oxygen absorbing layer are laminated in this order from the outer layer to the inner layer, and (2) a method in which the materials constituting each layer are melt-kneaded with an extruder corresponding to each layer of the gas barrier layer, the adhesive layer, and the oxygen absorbing layer, and then simultaneously melt-extruded through a multilayer die such as a T-die or a circular die to obtain a multilayer structure having a layer configuration in which the gas barrier layer, the adhesive layer, and the oxygen absorbing layer are laminated in this order from the outer layer to the inner layer.

[0050] [container] The container of the present invention is made of the multilayer structure of the present invention. The multilayer structure of the present invention has excellent oxygen barrier properties and oxygen absorption performance, is stiff, and when used in a multilayer configuration, has good adhesion to other layers, making it suitable for packaging containers for various articles.

[0051] The form of the container of the present invention is not particularly limited, and examples thereof include a lid, a tray, a pouch, and a laminated tube, with a tray being preferred among these.

[0052] Examples of items to be stored in the container include beverages such as milk, dairy products, juice, tea, and alcoholic beverages; liquid condiments such as sauce, soy sauce, and dressing, cooked foods such as soup, stew, curry, cooked foods for infants, and cooked foods for the elderly; paste-like foods such as jam, mayonnaise, ketchup, and jelly; seafood products such as tuna, fish and shellfish; dairy products such as cheese and butter; processed meat products such as meat, salami, sausage, and ham; vegetables such as carrots and potatoes; eggs; noodles; processed rice products such as uncooked rice, cooked rice, and rice porridge; dried foods such as powdered seasonings, powdered coffee, powdered milk for infants, and powdered diet foods; chemicals such as pesticides and insecticides; pharmaceuticals; cosmetics; pet food; miscellaneous items such as shampoo, conditioner, and detergent; and various other items. Among these, it is suitable for jellies, yokan, cooked rice, processed rice products, cooked foods for infants, cooked foods for the elderly, curries, soups, stews, jams, mayonnaise, ketchup, pet foods, and processed marine products using fruit pulp, fruit juice, coffee, etc., which are subjected to heat sterilization treatment such as boiling or retort treatment.

[0053] The container can be produced by a known method. For example, the multilayer sheet of the present invention can be molded into a container of a desired shape by hot molding, for example, vacuum molding, compressed air molding, plug-assist molding, or the like.

[0054] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention. EXAMPLES

[0055] The present embodiment will be described in detail below using examples and comparative examples, but the present embodiment can be modified as appropriate as long as the effects of the present invention are achieved.

[0056] <Material> The materials used in the examples and comparative examples are shown below. Polymethylpentene resin (A): A copolymer based on 4-methyl-1-pentene ("TPX (registered trademark) DX845" manufactured by Mitsui Chemicals, Inc.) Polyolefin resin (B): Linear low-density polyethylene (LLDPE, "KC580S" manufactured by Japan Polyethylene Co., Ltd.) Iron powder: average particle size 31.9μm, maximum particle size 55.0μm [Measuring particle size of iron powder] The particle size of the iron powder was measured using a laser diffraction / scattering particle size distribution measuring instrument ("SK Laser Micronsizer LMS-2000e" manufactured by Seishin Enterprise Co., Ltd.) in accordance with JIS Z8825:2013. The sample was prepared by adding two microspatulas of iron powder to 120 ml of isopropyl alcohol and dispersing it by ultrasonic treatment for one minute. Next, the sample was demagnetized using a magnetizer / demagnetizer (Niigata Seiki Co., Ltd.'s "Magnetouch MT-F"), and then the sample was placed in the dispersion unit of the above-mentioned measuring device and the particle size of the iron powder was measured using a circulation system. The average particle size and maximum particle size of the iron powder were determined as the particle size at 50% cumulative frequency (D50) and the particle size at 90% cumulative frequency (D90) in the volumetric particle size distribution, respectively. Calcium chloride: Tokuyama Corporation, reagent Adhesive: A mixture of dry lamination adhesive ("TM-250HV" manufactured by Toyo-Morton Co., Ltd.), dry lamination adhesive ("CAT-RT86L-60" manufactured by Toyo-Morton Co., Ltd.), and ethyl acetate (Fujifilm Wako Pure Chemical Co., Ltd., reagent) (mass ratio = 15.0:2.1:20.9)

[0057] (Production Example 1: Preparation of oxygen scavenger composition (C)) First, calcium chloride was mixed with water in a mass ratio of 1:1 to obtain a mixed calcium chloride aqueous solution. Next, the iron powder was placed in a vacuum mixer dryer equipped with a heating jacket, and while heating and drying at 130°C and a reduced pressure of 10 mmHg, 2 parts by mass of a calcium chloride mixed aqueous solution was sprayed per 100 parts by mass of the iron powder to prepare a granular oxygen absorbing composition (C) with calcium chloride adhered to the surface of the iron powder.

[0058] <Oxygen-absorbing resin composition, and production of molded body and multilayer structure using the same> Example 1 [1] Preparation of film (molded body) Polymethylpentene resin (A) and polyolefin resin (B) were mixed so that the mass ratio [(A) / (B)] was 5 / 95, and dry-blended. Then, the oxygen scavenger composition (C) prepared in Production Example 1 was added so that the content of the oxygen scavenger composition (C) in the oxygen absorbing resin composition was 30 mass %. The mixture was melt-kneaded at 260 to 270°C using a small twin-screw segment extruder ("2D15W" manufactured by Toyo Seiki Seisakusho Co., Ltd.), extruded through a strand die, cooled, and cut with a pelletizer to obtain pellets (oxygen absorbing resin composition). The obtained pellets were pressed under conditions of 230° C. and 70 kPa so as to have a thickness of 150 μm, to obtain a film (single layer) that was a molded product made of the oxygen-absorbing resin composition.

[0059] [2] Preparation of multilayer film (multilayer structure) Polymethylpentene resin (A) and polyolefin resin (B) were mixed so that the mass ratio [(A) / (B)] was 5 / 95, and dry-blended. The oxygen scavenger composition prepared in Production Example 1 was then added so that the content of the oxygen scavenger composition (C) in the oxygen absorbing resin composition was 30 mass %. The mixture was kneaded and extruded at an extrusion temperature of 260 to 270°C using a Labo Plastomill ("4C150" manufactured by Toyo Seiki Seisakusho Co., Ltd.), and a film was formed from a T-die to obtain a film (single layer, thickness: 100 μm) which is a molded product made of the oxygen absorbing resin composition. An adhesive was applied to the obtained film, which was then dried at 80°C for 1 minute, and then dry laminated with a transparent barrier film ("GL-ARH-F" manufactured by Toppan Printing Co., Ltd., thickness: 12 μm, inorganic vapor deposition PET film) using a laminator to obtain a multilayer film having a multilayer structure (structure: transparent barrier film (gas barrier layer) / adhesive layer / film which is a molded body made of an oxygen absorbing resin composition (oxygen absorbing layer), thickness: 120 μm).

[0060] (Examples 2 to 5 and Comparative Example 2) In Examples 2 to 5 and Comparative Example 2, films and multilayer films were produced in the same manner as in Example 1, except that the compounding ratio of the polymethylpentene resin (A) and the polyolefin resin (B) was changed to the value shown in Table 1.

[0061] Comparative Example 1 In Comparative Example 1, a film and a multilayer film were produced in the same manner as in Example 1, except that the polymethylpentene resin (A) was not used.

[0062] <Evaluation> The following evaluations were carried out using the films or multilayer films produced in the Examples and Comparative Examples. The results are shown in Table 1. Note that for the results of the Examples and Comparative Examples where some of the following evaluations were not carried out, a "-" symbol is added in the corresponding column in Table 1.

[0063] (oxygen absorption) The amount of oxygen absorbed was measured by the following method using the film prepared in [1] above. First, the film prepared in [1] above was cut to a size of 63 mm x 76 mm to obtain a measurement sample. One of the above measurement samples was placed in an aluminum foil laminated plastic film bag (manufactured by San-A Chemical Co., Ltd., size 220 mm x 200 mm, hereinafter referred to as "aluminum barrier bag") together with 500 ml of air at 25°C and absorbent cotton moistened with 10 ml of ion-exchanged water, and the opening was heat-sealed. Furthermore, the oxygen concentration (initial oxygen concentration) in the aluminum barrier bag at this time was measured. The aluminum barrier bag was then immediately placed in a constant temperature bath at 40°C and kept there for 5 days, after which the oxygen concentration inside the aluminum barrier bag (oxygen concentration after storage) was measured and the amount of oxygen absorbed (initial oxygen concentration - oxygen concentration after storage) was calculated. The oxygen concentration was measured using a gas analyzer (MOCON's "Check Mate 3") by inserting a hollow needle at the tip of a sampling silicon tube attached to the gas analyzer into the aluminum barrier bag through a sampling rubber sheet that had been attached to the aluminum barrier bag in advance, and measuring the oxygen concentration inside the aluminum barrier bag. The above measurement was carried out five times, and the average value was evaluated as the oxygen absorption amount of each example or comparative example sample. The larger the oxygen absorption amount, the better the oxygen absorption performance. In this example, samples with an oxygen absorption amount of 35.5 ml or more were evaluated as good.

[0064] (Young's Modulus) The Young's modulus was measured by the following method using the film prepared in [1] above. First, the film (thickness: 150 μm) prepared in [1] above was cut to a size of 15 mm width × 150 mm length to obtain a measurement sample. The longitudinal direction of the measurement sample was set as the tensile direction, and Young's modulus was measured using a Tensilon universal material testing machine ("RTG-1210" manufactured by A&D Co., Ltd.) in accordance with the provisions of JIS K7127:1999, with a chuck distance of 100 mm and a tensile speed of 50 mm / min. The above measurement was carried out five times, and the average value was evaluated as the Young's modulus of each example or comparative example sample. The larger the Young's modulus value, the higher the rigidity and firmness. In this example, samples with a Young's modulus of 240 MPa or more were evaluated as good.

[0065] (peel strength) The peel strength was measured by the following method using the multilayer film prepared in [2] above. First, the multilayer film (composition: gas barrier layer / adhesive layer / oxygen absorbing layer) prepared in [2] above was cut to a size of 15 mm width x 100 mm length to obtain a multilayer film piece. Next, two pieces of the resulting multilayer film were overlapped with the oxygen absorbing layers (films, which are molded bodies made of oxygen absorbing resin composition) facing each other, and heat sealed at 0.2 MPa for 1 second using a sealing bar heated to 170°C at the top and 100°C at the bottom to obtain a sample for measurement. The longitudinal direction of the measurement sample was set as the tensile direction, and the peel strength was measured using a Tensilon universal material testing machine ("RTG-1210" manufactured by A&D Co., Ltd.) in accordance with the provisions of JIS K7127:1999, with a chuck distance of 50 mm and a tensile speed of 300 mm / min. The above measurement was carried out three times, and the average value was evaluated as the peel strength of each example or comparative example sample. The peel surface was generally the interface between the oxygen absorbing layer and the adhesive layer. Therefore, the higher the peel strength value, the higher the adhesion between the oxygen absorbing layer and other layers. In this example, a peel strength of 5N / 15mm or more was evaluated as good.

[0066] [Table 1]

[0067] As shown in Table 1, it was confirmed that an oxygen absorbing resin composition containing a polymethylpentene resin (A), a polyolefin resin (B), and an oxygen scavenger composition (C), in which the mass ratio [(A) / (B)] of the polymethylpentene resin (A) to the polyolefin resin (B) is in the range of 1 / 99 to 65 / 35, can exhibit excellent oxygen absorbing performance and high Young's modulus (stiffness) (Examples 1 to 5). In addition, it was confirmed that an oxygen absorbing resin composition having a mass ratio [(A) / (B)] within a predetermined range has good adhesion to the adhesive layer, which is another layer, when it is made into a multi-layer structure (Examples 1 and 5).

[0068] On the other hand, it was confirmed that the oxygen-absorbing resin composition not containing the polymethylpentene resin (A) had a lower oxygen absorption amount and a lower Young's modulus (lack of stiffness) compared to the oxygen-absorbing resin compositions of the present invention described above (Examples 1 to 5). In particular, it was confirmed that the peel strength when made into a multi-layer structure was inferior to that of the oxygen-absorbing resin composition (Example 1) having a mass ratio [(A) / (B)] of 5 / 95 (Comparative Example 1). Furthermore, it was confirmed that when the mass ratio [(A) / (B)] of the polymethylpentene resin (A) to the polyolefin resin (B) exceeds 65 / 35, the peel strength is significantly reduced when the film is made into a multi-layer structure (Comparative Example 2).

Claims

1. An oxygen-absorbing resin composition comprising a polymethylpentene resin (A), a polyolefin resin (B) other than the polymethylpentene resin (A), and a deoxidizer composition (C), wherein the mass ratio [(A) / (B)] of the polymethylpentene resin (A) to the polyolefin resin (B) is 1 / 99 or more and 65 / 35 or less. The oxygen-absorbing resin composition.

2. The oxygen-absorbing resin composition according to Claim 1, wherein the deoxidizer composition (C) contains iron powder as a main component.

3. The oxygen-absorbing resin composition according to Claim 1, wherein the content of the deoxidizer composition (C) is 10% by mass or more and 85% by mass or less.

4. The oxygen-absorbing resin composition according to Claim 1, wherein the polyolefin resin (B) is one or more selected from the group consisting of polyethylene, polypropylene, polybutene, polybutadiene, and ethylene-propylene copolymer.

5. A molded article comprising the oxygen-absorbing resin composition according to any one of Claims 1 to 4.

6. The molded article according to Claim 5, wherein the molded article is a film or a sheet.

7. A multilayer structure comprising the film or sheet which is the molded article according to Claim 6.

8. A multilayer structure having a multilayer structure in which a gas barrier layer, an adhesive layer, and an oxygen absorption layer are laminated in this order, wherein the oxygen absorption layer is composed of the film or sheet which is the molded article according to Claim 6. The multilayer structure according to Claim 7.

9. The multilayer structure according to Claim 7, wherein the multilayer structure is a multilayer film or a multilayer sheet.

10. A container comprising the multilayer structure according to Claim 7.