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

Abstract

To provide an oxygen-absorbing resin composition having excellent oxygen-absorbing performance and odor suppressing performance, and a molded article, a multilayer structure and a container using the composition.SOLUTION: An oxygen-absorbing resin composition contains polymethylpentene resin (A), polyolefin resin (B) other than the polymethylpentene resin (A), and a deoxidant composition (C), where the deoxidant composition (C) contains iron powder as a main component, a mass ratio [(A) / (B)] between the polyolefin resin (B) and the polymethylpentene resin (A) is 5 / 95 or more and 80 / 20 or less, the polymethylpentene resin (A) and the polyolefin resin (B) form a phase separation structure, the phase separation structure is a sea-island structure in which a non-continuous phase (a) made of the polymethylpentene resin (A) is dispersed into a continuous phase (b) made of the polyolefin resin (B), and the deoxidant composition (C) is present in the non-continuous phase (a).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 use an oxygen absorbing composition in the form of 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 (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-90848 Summary of the Invention [Problem to be solved by the invention]

[0005] A packaging material in the form of a film or sheet containing an oxygen absorbing composition can have oxygen absorbing properties by itself. However, when a packaging material having such oxygen absorbing properties is used to store an oil-containing preserved article, the oxygen absorbing composition in the oxygen absorbing resin composition comes into contact with the oil in the preserved article and reacts with it, resulting in the generation of a peculiar odor. Therefore, there has been a demand for a resin material that can be used as a packaging material with excellent odor suppression performance. [Means for solving the problem]

[0006] 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 scavenger composition (C) contains iron powder as a main component, a mass ratio [(A) / (B)] of the polymethylpentene resin (A) to the polyolefin resin (B) is 5 / 95 or more and 80 / 20 or less; The polymethylpentene resin (A) and the polyolefin resin (B) form a phase-separated structure, the phase-separated structure is an island-sea structure in which a discontinuous phase (a) made of the polymethylpentene resin (A) is dispersed in a continuous phase (b) made of the polyolefin resin (B); The oxygen absorbing resin composition, wherein the oxygen scavenger composition (C) is present in the discontinuous phase (a). [2] The oxygen-absorbing resin composition according to the above [1], wherein the content of the oxygen scavenger composition (C) is 10 parts by mass or more and 500 parts by mass or less per 100 parts by mass of the polymethylpentene resin (A). [3] The oxygen-absorbing resin composition according to the above [1] or [2], wherein the polyolefin resin (B) is at least one selected from the group consisting of polyethylene, polypropylene, polybutene, polybutadiene and ethylene-propylene copolymer. [4] A molded article comprising the oxygen-absorbing resin composition according to any one of the above [1] to [3]. [5] The molded article according to the above [4], wherein the molded article is a film or a sheet. [6] A multilayer structure including the film or sheet which is the molded article according to the above [5]. [7] 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 the above [6], wherein the oxygen absorption layer is made of a film or a sheet which is the molded article according to the above [5]. [8] The multilayer structure according to the above [6] or [7], wherein the multilayer structure is a multilayer film or a multilayer sheet. [9] A container made of the multilayer structure according to any one of the above [6] to [8]. [Advantages of the Invention]

[0007] According to the present invention, it is possible to provide an oxygen-absorbing resin composition excellent in oxygen absorption performance and odor suppression ability, and a molded article, a multilayer structure, and a container using the same. [Brief Description of the Drawings]

[0008] [Figure 1] FIG. 1 is an SEM image obtained by cutting out a cross section perpendicular to the thickness direction of a film of an oxygen-absorbing resin composition (Example 4) of the present invention after resin embedding, processing it, and observing it with a field emission scanning electron microscope (FE-SEM). [Modes for Carrying Out the Invention]

[0009] Embodiments of the oxygen-absorbing resin composition according to the present invention, and a molded article, a multilayer structure, and a container using the same will be described in detail below. In the present 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 preferable modes is a more preferable mode.

[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), wherein the oxygen scavenger composition (C) contains iron powder as a main component, and the mass ratio of the polymethylpentene resin (A) to the polyolefin resin (B) [(A) / (B)] is 5 / 95 or more and 80 / 20 or less, the polymethylpentene resin (A) and the polyolefin resin (B) form a phase-separated structure, and the phase-separated structure is a sea-island structure in which a discontinuous phase (a) made of the polymethylpentene resin (A) is dispersed in a continuous phase (b) made of the polyolefin resin (B), and the oxygen scavenger composition (C) is present in the discontinuous phase (a).

[0011] As described above, the oxygen-absorbing resin composition of the present invention has a phase-separated structure formed by the polymethylpentene resin (A) (hereinafter also referred to as "component (A)") and the polyolefin resin (B) (hereinafter also referred to as "component (B)") The phase-separated structure is a sea-island structure in which the discontinuous phase (a) made of the polymethylpentene resin (A) is dispersed in the continuous phase (b) made of the polyolefin resin (B). In this specification, the term "sea-island structure" refers to a phase-separated structure in which one type of domain among the phase-separated structure domains forms a continuous phase (sea), and the other domains form discontinuous phases (islands).

[0012] Furthermore, the oxygen-absorbing resin composition of the present invention contains an oxygen scavenger composition (C) (hereinafter also referred to as "component (C)"), and the oxygen scavenger composition (C) is present in the discontinuous phase (a). In this specification, "the oxygen scavenger composition (C) is present in the discontinuous phase (a)" mainly refers to a state in which the oxygen scavenger composition (C) is coated with the polymethylpentene resin (A) or embedded in the discontinuous phase (a) made of the polymethylpentene resin (A). Note that, within the scope that does not impair the effects of the present invention, a part of the oxygen scavenger composition (C) may also be present in the continuous phase (b) made of the polyolefin resin (B) or on the interface between the discontinuous phase (a) and the continuous phase (b). In addition, the term "sea-island structure in which a discontinuous phase (a) made of polymethylpentene resin (A) is dispersed in a continuous phase (b) made of polyolefin resin (B)" refers not only to the case in which the polymethylpentene resin (A) alone forms the discontinuous phase (a), but also to the case in which the polymethylpentene resin (A) is coated with the oxygen scavenger composition (C) and is dispersed as a whole in the continuous phase (b) in the form of islands.

[0013] In the oxygen absorbing resin composition of the present invention, the method for confirming the above-mentioned predetermined sea-island structure and the location of the oxygen scavenger composition (C) is not necessarily limited, but examples thereof include a method for estimating the above-mentioned structure from the manufacturing method of the oxygen absorbing resin composition, and a method for confirming by observation with a microscope such as a field emission scanning electron microscope (FE-SEM). Specifically, they can be confirmed by the method described in the Examples.

[0014] The reason why the oxygen-absorbing resin composition of the present invention having the above-mentioned characteristics is able to exhibit excellent oxygen-absorbing performance and odor-suppressing ability is not clear, but the following reasons are thought to be the cause.

[0015] 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 particles of the oxygen absorbing composition from protruding when molded into a film or sheet. However, when an oxygen-absorbing resin composition using a polyolefin resin (B) such as a polyethylene resin is formed into a film or sheet to store an oil-containing preserved item, the oxygen scavenger composition (C) in the oxygen-absorbing resin composition comes into contact with the oil in the preserved item and reacts with it, resulting in the generation of a peculiar odor. This problem of odor generation was particularly noticeable when the oxygen scavenger composition (C) contained iron powder as a main component. The reason for this is not entirely clear, but one possible explanation is that the iron powder in the oxygen scavenger composition reacts with oil to produce a reaction product between the iron and oil, which generates a unique odor similar to that of iron.

[0016] Furthermore, in the conventional oxygen-absorbing resin composition using a polyolefin resin (B) such as a polyethylene resin, the problem of odor generation as described above occurs, firstly, because the polyolefin resin (B) such as polyethylene has a relatively low oil resistance. In addition, since the polyolefin resin (B) such as polyethylene has a relatively low melting point and poor flexibility, when the oxygen-absorbing resin composition is formed into a film or sheet, the particles of the oxygen scavenger composition (C) may protrude, exposing the surface of the oxygen scavenger composition (C) to the outside. Therefore, the present inventors have investigated an oxygen-absorbing resin composition that can prevent the surface of the oxygen scavenger composition (C) from being exposed to the outside world, and have focused on polymethylpentene resin (A) from the viewpoint of solving the above-mentioned problems.

[0017] First, the polymethylpentene resin (A) used in the present invention is a resin with low compatibility, and is therefore incompatible with the polyolefin resin (B) other than the polymethylpentene resin (A), and is capable of forming a phase-separated structure (microphase-separated structure). As a result of further investigations, the present inventors have found that by preparing an oxygen-absorbing resin composition containing polymethylpentene resin (A) and polyolefin resin (B) in a specific ratio, the phase-separated structure between components (A) and (B) can be made into a sea-island structure in which discontinuous phase (a) made of component (A) is dispersed in continuous phase (b) made of component (B), and in particular, by having oxygen scavenger composition (C) be present in the discontinuous phase (a) made of component (A), films and sheets having excellent oxygen absorption performance and odor suppression performance can be obtained, thereby completing the present invention.

[0018] First, in a sea-island structure in which discontinuous phase (a) made of component (A) is dispersed in continuous phase (b) made of component (B), the discontinuous phase (a) is surrounded by continuous phase (b) made of component (B). In such a phase-separated structure, by having oxygen scavenger composition (C) present in discontinuous phase (a) made of component (A), even if particles of component (C) protrude from the discontinuous phase (a), it is believed that the continuous phase (b) made of component (B) is present outside the discontinuous phase (a), and therefore the particle surfaces of component (C) can be effectively prevented from being exposed to the outside world. In addition, since the polymethylpentene resin (A) has a higher glass transition temperature than the polyolefin resin (B) such as polyethylene resin, it exhibits plasticity when heated during molding the oxygen absorbing resin composition into a film or sheet, but does not flow as much as polyethylene resin. Therefore, it is considered that the particle surfaces of the oxygen scavenger composition (C) can be well coated and the particle surfaces can be effectively prevented from being exposed to the outside world. Furthermore, since the polymethylpentene resin (A) has high oil resistance to begin with, it is believed that by having the oxygen scavenger composition (C) be present in the discontinuous phase (a) consisting of the (A) component, the oxygen scavenger composition (C) can be effectively prevented from coming into contact with oil. According to the oxygen-absorbing resin composition of the present invention, even when the oxygen-absorbing resin composition is formed into a film or sheet to preserve food or other preserved objects containing oil, it is presumed that the oil can be prevented from coming into contact with the oxygen scavenger composition (C) and reacting with the oil, thereby preventing the generation of a peculiar odor.

[0019] In addition, since the polymethylpentene resin (A) used in the present invention has a higher oxygen permeability than the polyolefin resin (B) such as a polyethylene resin, the contact of the oxygen scavenger composition (C) with oil is suppressed, but the contact and reaction of the oxygen scavenger composition (C) with oxygen can be adequately ensured, and it is presumed that the oxygen absorption performance of the oxygen scavenger composition (C) can be improved.

[0020] The above-mentioned effects are achieved by the presence of the oxygen scavenger composition (C) in the discontinuous phase (a) made of the component (A). However, within the scope of not impairing the effects of the present invention, a part of the oxygen scavenger composition (C) may also be present in the continuous phase (b) made of the polyolefin resin (B) or on the interface between the discontinuous phase (a) and the continuous phase (b). However, the lower the proportion of the oxygen scavenger composition (C) present in the discontinuous phase (a), the lower the above-mentioned effect. Therefore, when the total amount of the oxygen scavenger composition (C) is taken as 100 mass%, the proportion of the oxygen scavenger composition (C) present in the discontinuous phase (a) is preferably 60 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and still more preferably 95 mass% or more. The proportion of the oxygen scavenger composition (C) can be estimated, for example, by observing any cross section of a film or sheet made of the oxygen absorbing resin composition and estimating the area ratio of the (C) component present therein. For example, in any cross section, the area of ​​all the (C) components is taken as 100%, and the area ratio (%) of the oxygen scavenger composition (C) present in the discontinuous phase (a) may be calculated. Furthermore, taking into consideration variations in each cross section, it is preferable to average the area ratios over at least three or more cross sections. From the viewpoint of further enhancing the above-mentioned effects, it is particularly preferred that the oxygen scavenger composition (C) is present only in the discontinuous phase (a) consisting essentially of the component (A).

[0021] The method for making the oxygen scavenger composition (C) exist in the discontinuous phase (a) consisting of the polymethylpentene resin (A) is not particularly limited. For example, there can be mentioned a method in which, in the production process of the oxygen absorbing resin composition, a master batch (X) in which the (C) component is dispersed in the (A) component is prepared in advance, and the master batch (X) is kneaded with the (B) component to obtain the oxygen absorbing resin composition.

[0022] Hereinafter, each component contained in the oxygen-absorbing resin composition of the present invention will be described.

[0023] <Polymethylpentene resin (A)> The polymethylpentene resin (A) is a thermoplastic resin and functions as a matrix component of the oxygen absorbing resin composition. In the phase-separated structure (sea-island structure) of the components (A) and (B), the component (A) is a discontinuous phase (a). 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.

[0024] 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 %.

[0025] 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.

[0026] Commercially available examples of the polymethylpentene resin (A) used in the present invention include the TPX (registered trademark) series manufactured by Mitsui Chemicals, Inc.

[0027] The content of the polymethylpentene resin (A) in the oxygen-absorbing resin composition is, for example, 2 mass% or more and 90 mass% or less, preferably 4 mass% or more and 80 mass% or less, more preferably 5 mass% or more and 70 mass% or less, even more preferably 8 mass% or more and 65 mass% or less, and even more preferably 8 mass% or more and 50 mass% or less.

[0028] <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.

[0029] The content of the polyolefin resin (B) in the oxygen-absorbing resin composition is, for example, 10% by mass or more and 90% by mass or less, preferably 10% by mass or more and 80% by mass or less, more preferably 15% by mass or more and 76% by mass or less, and even more preferably 30% by mass or more and 73% by mass or less.

[0030] The total content of the polymethylpentene resin (A) and the polyolefin resin (B) in the oxygen-absorbing resin composition is preferably 34 mass% or more and 90 mass% or less, more preferably 50 mass% or more and 90 mass% or less, and even more preferably 55 mass% or more and 85 mass% or less.

[0031] The mass ratio [(A) / (B)] of the polymethylpentene resin (A) to the polyolefin resin (B) in the oxygen-absorbing resin composition is from 5 / 95 to 80 / 20. By setting it within the above range, the phase separation structure between the components (A) and (B) can be a predetermined sea-island structure, and further, by having the oxygen scavenger composition (C) exist in the discontinuous phase (a) consisting of the component (A), excellent oxygen absorbing performance and odor suppressing ability can be exhibited. On the other hand, in an oxygen-absorbing resin composition in which the mass ratio [(A) / (B)] is less than 5 / 95 or more than 80 / 20, the phase-separated structure between the (A) component and the (B) component cannot be formed into the specified sea-island structure, and therefore the oxygen-absorbing performance and odor-suppressing performance are inferior.

[0032] In particular, when the mass ratio [(A) / (B)] is less than 5 / 95, polyolefin resin (B) may be present around the oxygen scavenger composition (C). Since polyolefin resin (B) has a lower glass transition temperature than polymethylpentene resin (A), when the oxygen absorbing resin composition is molded into a film or sheet, particles of the oxygen scavenger composition (C) may protrude and the surface of the oxygen scavenger composition (C) may be exposed to the outside. This may cause contact between oil and the oxygen scavenger composition (C), which tends to easily generate odor. In addition, since polyolefin resin (B) has a lower oxygen permeability than polymethylpentene resin (A), when the oxygen scavenger composition (C) is embedded in polyolefin resin (B), contact with oil is suppressed, but contact with oxygen is also suppressed, so that the original oxygen absorption performance of the oxygen scavenger composition (C) tends not to be exhibited.

[0033] On the other hand, when the mass ratio [(A) / (B)] is more than 80 / 20, the polyolefin resin (B) cannot form the continuous phase (b). As a result, the (A) component does not form a phase-separated structure surrounded by the (B) component, and when the particles of the oxygen scavenger composition (C) present in the discontinuous phase (a) made of the (A) component protrude, the surface of the (C) component may be exposed to the outside. This causes contact between the oil and the oxygen scavenger composition (C), which tends to easily generate odor.

[0034] In the oxygen-absorbing resin composition of the present invention, from the viewpoint of exhibiting excellent oxygen absorption performance and odor suppression performance, the mass ratio [(A) / (B)] is preferably 5 / 95 or more and 70 / 30 or less, more preferably 10 / 90 or more and 60 / 40 or less, even more preferably 10 / 90 or more and 50 / 50 or less, and still more preferably 10 / 90 or more and 40 / 60 or less.

[0035] <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).

[0036] The oxygen scavenger composition (C) contains iron powder as a main component. As such an oxygen scavenger composition (C), an oxygen scavenger composition comprising iron powder and a metal halide is particularly preferred, and an oxygen scavenger composition in which a metal halide is adhered to iron powder is more preferred. The content of 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 99.9% by mass or less, preferably 99% by mass or less. Specifically, the content of 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 99.9% by mass or less, more preferably 86% by mass or more and 99% by mass or less.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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. The metal halide is preferably dissolved in water and then coated on the iron powder.

[0041] 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.

[0042] The content of the oxygen scavenger composition (C) is preferably 10 parts by mass or more and 600 parts by mass or less, more preferably 10 parts by mass or more and 500 parts by mass or less, even more preferably 20 parts by mass or more and 500 parts by mass or less, even more preferably 30 parts by mass or more and 500 parts by mass or less, and even more preferably 40 parts by mass or more and 500 parts by mass or less, relative to 100 parts by mass of the polymethylpentene resin (A). When the content of the oxygen scavenger composition (C) is within the above range, the oxygen scavenger composition (C) can be well present in the discontinuous phase (a) consisting of the (A) component, so that excellent oxygen absorption performance and odor suppression ability can be exhibited. From the viewpoint of workability during the preparation of the oxygen absorbing resin composition, the content of the oxygen scavenger composition (C) is preferably 300 parts by mass or less relative to 100 parts by mass of the polymethylpentene resin (A). The content of the oxygen scavenger composition (C) in the oxygen absorbing resin composition is preferably 10% by mass or more and 66% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% 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 odor suppressing ability is also exhibited.

[0043] <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.

[0044] 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).

[0045] 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.

[0046] <Manufacturing method> The method for producing the oxygen-absorbing resin composition of the present invention may, for example, be as follows. The method for producing the oxygen-absorbing resin composition of the present invention preferably includes a step (I) of kneading a polymethylpentene resin (A) with an oxygen scavenger composition (C) to obtain a master batch (X), and a step (II) of kneading the master batch (X) with a polyolefin resin (B) to obtain an oxygen-absorbing resin composition. In particular, by pre-mixing (pre-mixing) the polymethylpentene resin (A) and the oxygen scavenger composition (C) in the above step (I) to obtain the master batch (X), the oxygen scavenger composition (C) can be well coated with the polymethylpentene resin (A). Furthermore, by kneading the master batch (X) with the polyolefin resin (B) in the above step (II), a desired sea-island structure can be well formed, and the oxygen scavenger composition (C) can be properly present in the discontinuous phase (a) made of the polymethylpentene resin (A). In addition, when an additive is added, from the viewpoint of uniformly dispersing the additive, it is preferable to knead the additive into the polyolefin resin (B) to prepare a master batch (Y), and then knead the master batch (X) and the master batch (Y).

[0047] [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 odor suppressing ability.

[0048] 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."

[0049] 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.

[0050] 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.

[0051] The conditions for melt-kneading and extrusion can be publicly known conditions, but from the viewpoint of allowing the oxygen scavenger composition (C) to be well present in the discontinuous phase (a) made of the polymethylpentene resin (A), it is preferable to use conditions that do not cause the polymethylpentene resin (A) to flow too much. This makes it possible to prevent the oxygen scavenger composition (C) from being separated from the discontinuous phase (a) made of the polymethylpentene resin (A) due to heating during melt-kneading and extrusion. Specifically, the kneading temperature is preferably 240 to 280°C, and the extrusion temperature is preferably 250 to 280°C.

[0052] [Multilayer structure] The multilayer structure of the present invention includes the film or sheet which is the molded article of the present invention. Such a multilayer structure has excellent oxygen absorption performance and odor suppression performance. 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.

[0053] <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.

[0054] 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 material or a plurality of materials. When made of a plurality of materials, the materials may be laminated, and by using the materials in a laminated state, a higher barrier effect can be exhibited.

[0055] <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.

[0056] <Oxygen absorbing layer> The oxygen absorbing layer is preferably made of a film 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), in which the mass ratio of the component (A) to the component (B) [(A) / (B)] is 5 / 95 or more and 80 / 20 or less, the components (A) and (B) form a phase-separated structure, and the phase-separated structure is a sea-island structure in which a discontinuous phase (a) made of the component (A) is dispersed in a continuous phase (b) made of the component (B), and the component (C) is present in the discontinuous phase (a). Therefore, the oxygen absorbing layer is preferably made of the oxygen absorbing resin composition having the respective components, respective ratios, and phase-separated structure described in the section [Oxygen absorbing resin composition] above.

[0057] The suitable thickness of the oxygen absorbing layer is similar to the thickness of the molded article. When the molded article is a film, it is, for example, 10 μm or more and less than 250 μm, preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 200 μm or less, and when the molded article is a sheet, it 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 and odor suppressing performance are excellent, and the cost efficiency and processability are good.

[0058] <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.

[0059] 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.

[0060] 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."

[0061] 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.

[0062] 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.

[0063] [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 absorption performance and odor suppression performance, and is therefore suitable as a packaging container for various articles.

[0064] 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 trays and pouches being preferred among these.

[0065] In addition, the items to be stored in the container include, for example, sweets such as chocolate confectionery, jelly with fruit pulp, yokan, pudding, etc.; fruits such as pineapple, mandarin orange, peaches, apricots, pears, apples, etc.; beverages such as drinking water, tea drinks, coffee drinks, soft drinks, juice, alcoholic drinks, milk, dairy products, etc.; seasonings such as liquid soup stock, mayonnaise, ketchup, sauce, soy sauce, dressing, miso, grated spices, etc.; cooked foods such as soup, stew, curry, simmered dishes, pickles, cooked foods for infants, and cooked foods for the elderly; paste-like foods such as jam, cream, chocolate paste, jelly, etc.; marine products such as tuna, fish and shellfish; cheese, Examples of such products include dairy products such as butter; meats such as beef, pork, and chicken; processed meat products such as salami, sausage, and ham; vegetables such as lettuce, radish, cucumber, carrot, and potato; eggs; noodles such as soba, udon, and ramen, both raw and boiled; uncooked rice such as polished rice, moisture-conditioned rice, and pre-rinsed rice; processed rice products such as cooked rice, mixed rice, red rice, and rice porridge; dried foods such as powdered soup, powdered seasonings such as dashi stock, powdered coffee, powdered milk for infants, and powdered diet foods; chemicals such as pesticides and insecticides; pharmaceuticals; cosmetics; pet food; miscellaneous goods such as shampoo, conditioner, and detergent; and various other items.

[0066] Among these, the present invention is particularly suitable for foods containing lipids in an amount of 1% by mass or more and 50% by mass or less. Such foods are prone to deterioration due to oxygen, and are also prone to the problem of the generation of the above-mentioned unique odor. However, by using the multilayer body of the present embodiment as a packaging container or the like, the generation of the above-mentioned unique odor can be effectively suppressed. More specifically, such foods include chocolate confectionery containing 1% to 50% by mass of lipids, and meat (e.g., beef) containing 1% to 50% by mass of lipids. In the case of the chocolate confectionery, the packaging container of the present embodiment is particularly useful when storing at room temperature (e.g., 25°C), and in the case of meat, the packaging container of the present embodiment is particularly useful when storing under refrigerated conditions (e.g., 5°C to 10°C).

[0067] 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.

[0068] 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

[0069] 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.

[0070] <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. To prepare the sample, two microspatulas of iron powder were placed in 120 ml of isopropyl alcohol and ultrasonicated for one minute to disperse the powder. 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

[0071] (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.

[0072] <Oxygen-absorbing resin composition, and production of molded body and multilayer structure using the same> Example 1 Polymethylpentene resin (A) and the oxygen scavenger composition (C) prepared in Production Example 1 were mixed so that the mass ratio [(A) / (C)] was 4 / 20, and the mixture was melt-kneaded (temperature 260-270°C, kneading time 10 minutes) using a small twin-screw segment extruder (Toyo Seiki Seisakusho Co., Ltd., "2D15W"), extruded through a strand die, cooled, and cut with a pelletizer to obtain kneaded pellets (X) (Step I). Next, the obtained kneaded pellets (X) and polyolefin resin (B) were mixed so that the mass ratio [(X) / (B)] was 24 / 76, and dry-blended. The mixture was then kneaded and extruded (temperature: 260-270°C, kneading time: approximately 5 minutes) using a Labo Plastomill ("4C150" manufactured by Toyo Seiki Seisakusho Co., Ltd.), and formed into a film from a T-die to obtain a film (single layer, thickness: 130 μm) that was a molded product made of the oxygen-absorbing resin composition (Step II).

[0073] (Examples 2 to 6 and Comparative Example 2) In Examples 2 to 6 and Comparative Example 2, 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.

[0074] Comparative Example 1 In Comparative Example 1, a film was produced in the same manner as in Example 1, except that the polymethylpentene resin (A) was not used.

[0075] Comparative Example 3 First, polymethylpentene resin (A) and polyolefin resin (B) were mixed and dry-blended so that the mass ratio [(A) / (B)] was 57.2 / 22.8. Next, the oxygen scavenger composition prepared in Production Example 1 was added so that the content of the oxygen scavenger composition (C) in the oxygen absorbing resin composition was 20 mass%, and the mixture was kneaded and extruded (temperature: 260-270°C, kneading time: about 5 minutes) using a Labo Plastomill (manufactured by Toyo Seiki Seisakusho Co., Ltd., "4C150"), and film-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.

[0076] <Evaluation> The films prepared in the examples and comparative examples were subjected to the following evaluations. The results are shown in Table 1. (oxygen absorption) The amount of oxygen absorbed was measured by the following method using the films prepared in the above Examples and Comparative Examples. First, the films prepared in the above Examples and Comparative Examples were cut to a size of 63 mm x 76 mm to obtain a measurement sample. The two measurement samples were 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 thermostatic chamber at 25°C and kept there for 7 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 three 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 24.0 ml or more were evaluated as good.

[0077] (Odor evaluation) The odor was evaluated by the following method using the films prepared in the above Examples and Comparative Examples. First, the films prepared in the above Examples and Comparative Examples were cut to a size of 63 mm x 76 mm to obtain a measurement sample. Next, 6 ml of ion-exchanged water and 3 ml of salad oil were each dropped in a swirling pattern onto absorbent cotton (75 mm x 140 mm) using a dropper, and further pressure was applied to the absorbent cotton to confirm that the water and oil had permeated the entire absorbent cotton. The absorbent cotton soaked evenly with the water and oil was folded in half lengthwise, and one sheet of the measurement sample was sandwiched inside (the valley fold side) of the folded absorbent cotton (75 mm x 70 mm). This was then placed in an aluminum foil laminated plastic film bag (manufactured by San-A Chemical Co., Ltd., size 180 mm x 250 mm, hereafter referred to as "aluminum barrier bag") together with 500 ml of air at 25°C, and the opening was heat sealed to seal. The aluminum barrier bag was then immediately placed in a thermostatic chamber at 25° C. and held there for 5 days. After that, the aluminum barrier bag was opened and a panel of smell testers smelled the odor inside the bag. The above evaluation was carried out by three odor panelists, who first confirmed the presence or absence of the "iron odor" that is considered to be the cause of the unique odor. Furthermore, the odor strength was judged according to the following evaluation criteria, and the odor strength judgment result of the panelist who sensed the strongest odor among the three odor panelists was evaluated as the odor strength of each Example or Comparative Example sample. In this Example, samples with an odor strength of "A" or "B" were evaluated as good. The number of panelists who detected an iron odor and the evaluation results for odor intensity are shown in Table 1. <Evaluation criteria> A: I can't smell anything. B: A weak odor that can be smelled if you smell it consciously C: A strong odor that cannot be smelled for long D: A strong odor that you can no longer smell immediately

[0078] [Table 1]

[0079] As shown in Table 1, polymethylpentene resin (A) and oxygen scavenger composition (C) were pre-kneaded to prepare a master batch (X) (step I) so as to obtain a predetermined composition, and the master batch (X) was then kneaded with a polyolefin resin (B) (step II) to prepare an oxygen scavenger composition. The polymethylpentene resin (A) and the polyolefin resin (B) formed a phase-separated structure, and the phase-separated structure was a sea-island structure in which a discontinuous phase (a) made of the polymethylpentene resin (A) was dispersed in a continuous phase (b) made of the polyolefin resin (B), and the oxygen scavenger composition (C) was present in the discontinuous phase (a). As a result, it was confirmed that the oxygen scavenger composition could exhibit excellent oxygen absorption performance and odor suppression performance (Examples 1 to 6).

[0080] On the other hand, it was confirmed that the oxygen-absorbing resin composition not containing the polymethylpentene resin (A) (Comparative Example 1) was inferior in oxygen absorption capacity and odor suppression capacity compared to the oxygen-absorbing resin compositions of the present invention (Examples 1 to 6). Furthermore, when the mass ratio [(A) / (B)] of the polymethylpentene resin (A) to the polyolefin resin (B) exceeds 80 / 20, a phase separation structure is formed, but the continuous phase (a) of the polymethylpentene resin (A) is dispersed with the discontinuous phase (b) of the polyolefin resin (B), resulting in an island-sea structure that is the opposite of the predetermined island-sea structure defined in the present invention. Therefore, it was confirmed that the oxygen absorption capacity and odor suppression capacity were inferior to those of the oxygen-absorbing resin compositions of the present invention (Examples 1 to 6) (Comparative Example 2). In addition, it was confirmed that an oxygen scavenger composition prepared by kneading and extruding polymethylpentene resin (A), polyolefin resin (B), and oxygen scavenger composition (C) all at once without previously kneading the polymethylpentene resin (A) and the polyolefin resin (B) (without carrying out step I) had poor oxygen absorption capacity and odor suppression capacity because the oxygen scavenger composition (C) was mainly present in the continuous phase (b) (Comparative Example 3).

[0081] (Structural observation) Furthermore, the structure of the oxygen-absorbing resin composition prepared in Example 4 was observed by the following method. First, the film prepared in Example 4 was cut to a size of 1 mm x 5 mm to obtain a sample for observation. Next, the above-mentioned observation sample was embedded in resin, and cut perpendicular to the thickness direction of the film (cross section) using an ultramicrotome at room temperature (25° C.±5° C., the same applies below). In order to more clearly distinguish the sea-island structure, the processed surface was subjected to vapor-phase staining with RuO4 for 1 hour. Thereafter, the cut surface was again processed using an ultramicrotome at room temperature (finishing treatment). The processed surface of the prepared observation sample was observed at 1000x secondary electron images from the perpendicular direction to the processed surface using a field emission scanning electron microscope (FE-SEM, Hitachi High-Tech Corporation, "SU8220") at an accelerating voltage of 2 kV, and a cross-sectional photograph (SEM image, 95.3 μm long × 127 μm wide) was obtained (Figure 1). In the above-mentioned room temperature processing with an ultramicrotome, the section corresponding to the polymethylpentene resin (A) is processed to have a flat cross section because its glass transition temperature (Tg) is generally higher than room temperature, whereas the section corresponding to the LLDPE is processed to have a wrinkled cross section because its glass transition temperature (Tg) is generally lower than room temperature. Therefore, as shown in FIG. 1, in the cross-sectional photograph, the polymethylpentene resin (A) phase is observed as a flat surface, and the LLDPE phase, which is the polyolefin resin (B), is observed as a wrinkled surface. As a result of the observation, in the oxygen absorbing resin composition of Example 4, a sea-island structure was observed in which the wrinkled surface corresponding to the LLDPE phase constituted the continuous phase (A), and the flat surface corresponding to the polymethylpentene resin (A) phase constituted the discontinuous phase (B), which were scattered like islands in the continuous phase (A). Furthermore, it was confirmed that the oxygen scavenger composition (C) was mainly arranged so as to be embedded in the discontinuous phase (a).

Claims

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 scavenger composition (C) contains iron powder as a main component, a mass ratio of the polymethylpentene resin (A) to the polyolefin resin (B) [(A) / (B)] is 5 / 95 or more and 80 / 20 or less; the polymethylpentene resin (A) and the polyolefin resin (B) form a phase-separated structure, the phase-separated structure is a sea-island structure in which a discontinuous phase (a) made of the polymethylpentene resin (A) is dispersed in a continuous phase (b) made of the polyolefin resin (B), The oxygen-absorbing resin composition, wherein the oxygen scavenger composition (C) is present in the discontinuous phase (a).

2. 2. The oxygen-absorbing resin composition according to claim 1, wherein the content of the oxygen scavenger composition (C) is 10 parts by mass or more and 500 parts by mass or less per 100 parts by mass of the polymethylpentene resin (A).

3. 2. The oxygen-absorbing resin composition according to claim 1, wherein the polyolefin resin (B) is at least one selected from the group consisting of polyethylene, polypropylene, polybutene, polybutadiene, and ethylene-propylene copolymer.

4. A molded article comprising the oxygen-absorbing resin composition according to any one of claims 1 to 3.

5. The molded article according to claim 4 , which is a film or a sheet.

6. A multilayer structure comprising a film or sheet which is the molded article according to claim 5.

7. A multilayer structure having a multilayer structure in which a gas barrier layer, an adhesive layer, and an oxygen absorbing layer are laminated in this order, 7. The multilayer structure according to claim 6, wherein the oxygen-absorbing layer comprises a film or sheet that is the molded article according to claim 5.

8. The multilayer structure according to claim 6, wherein the multilayer structure is a multilayer film or a multilayer sheet.

9. A container comprising the multilayer structure according to claim 6.

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