JP2015007148A - Oxygen-absorbing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen-absorbing resin composition having a less moisture content and an ability of absorbing oxygen in the atmosphere even under an atmosphere almost free of moisture.SOLUTION: There is provided an oxygen-absorbing resin composition which comprises: an oxygen absorbent (I) which contains a metal (metal of (I)) obtained by treating an alloy containing (A) at least one transition metal selected from the group consisting of iron, cobalt, nickel and copper and (B) aluminum with an alkali aqueous solution and eluting and removing at least a part of the component (B) and in which the metal obtained by eluting and removing a part of the component (B) has a specific surface area measured by BET method of at least 10 m2/g; and (II) a thermoplastic resin. The oxygen absorbing resin composition has a moisture content of 5000 ppm or less.

Description

  The present invention relates to an oxygen-absorbing resin composition containing an oxygen absorbent composed of an oxygen-absorbing metal and a thermoplastic resin. Specifically, the present invention relates to an oxygen-absorbing resin composition having a low water content, and relates to an oxygen-absorbing resin composition capable of absorbing and removing oxygen even in a low humidity atmosphere. The present invention further relates to an oxygen-absorbing film or oxygen-absorbing sheet using the oxygen-absorbing resin composition. Furthermore, the present invention relates to a method for preserving an article using the oxygen-absorbing resin, the oxygen-absorbing film or the oxygen-absorbing sheet.

  One storage technique for foods and pharmaceuticals is a storage technique using an oxygen absorbent (deoxygenating agent). Specifically, an oxygen scavenger that removes oxygen in the atmosphere is placed inside the sealed package together with the object, and the inside of the sealed package is made oxygen-free, thereby causing oxidative degradation, mold, This technology suppresses discoloration and the like.

  So far, oxygen absorbers that remove oxygen in the atmosphere have been proposed from various inorganic materials and organic materials. For example, metal powder such as iron as an inorganic main ingredient, sulfite, bisulfite, nitrite, etc., organic main ingredient L-ascorbic acid, erythorbic acid and their salts, sugars such as glucose, Examples include those using reducing polyhydric alcohols such as catechol and pyrogallol.

  However, these conventional oxygen scavengers have a problem that a practical oxygen scavenging ability cannot be obtained unless water or moisture is supplied at the time of use. That is, conventional oxygen scavengers use water or a substance that retains moisture, such as a compound having water of crystallization, or water vapor generated from food to be stored. For the first time, practical deoxygenation ability could be obtained.

For example, an organic EL element having excellent features such as high-speed response, high contrast, high brightness, high viewing angle, and high definition, which is attracting attention as a next-generation display element, is an electrode due to a small amount of moisture and oxygen present inside the element. It is considered that non-light emitting portions (dark spots) are generated due to the deterioration of the conductivity due to the deterioration of materials and organic compounds, and the light emission characteristics are deteriorated.

Moisture is also believed to promote the hydrolysis of medicinal ingredients, the decay of dried foods, and the corrosion of metal products.

  For this reason, in these applications, an oxygen absorbent that does not require moisture during oxygen absorption has been demanded. Examples of oxygen absorbers that can meet such requirements include (a) a deoxygenating agent based on cerium oxide using oxygen defects (Patent No. 4001614 (Patent Document 1)), and (b) oxygen defects. An oxygen scavenger based on titanium oxide (Japanese Patent No. 4248986 (Patent Document 2)), and (c) a oxygen scavenger based on a metal subjected to hydrogen reduction (Japanese Patent Laid-Open No. 62-277148 (patent No. 2). References 3)), and (d) oxygen scavengers utilizing auto-oxidation of organic substances have been reported.

  However, among the above (a) and (b), the metal used as a raw material for these oxygen scavengers is a rare metal and is therefore rare and expensive. In addition, imports from overseas must be relied on, and depending on the situation, purchases may fluctuate and stable production may not be expected. For this reason, it was not necessarily satisfactory from the viewpoint of cost and stable supply. Moreover, since it is necessary to attach a large-scale hydrogen reduction facility to the above (c), it is not a simple method and it cannot be said that it is easy to handle in the atmosphere. Furthermore, since the above (d) uses an organic oxidation reaction as a main agent, there is a problem of by-products generated after oxygen absorption.

  For this reason, it is an oxygen-absorbing resin composition having the ability to absorb oxygen in the atmosphere even in an atmosphere with little or no moisture, and the raw material is relatively inexpensive and stable, and is a problem of by-products There is still a need for a device that does not require a large-scale apparatus as in the case of performing hydrogen reduction.

  In recent years, it has been practiced to package an object to be stored using a sheet-shaped packaging material obtained by kneading an oxygen scavenger with a resin to form a sheet or film (for example, Japanese Patent No. 3396427 (Patent Document 4) and International Publication WO2010 / 147097 (Patent Document 5)). It has been desired to use a sheet-like packaging material also in rust-preserving of pharmaceutical products or dried foods that need to be used or stored under dry conditions, and metal products that dislike the presence of water or moisture. That is, even in the case of an oxygen-absorbing sheet-like packaging material in the form of a sheet or film, a material having an ability to absorb oxygen in the atmosphere has been desired even in an atmosphere with little or no moisture. .

  Even in an atmosphere with little or no moisture, it has the ability to absorb oxygen in the atmosphere, the raw materials are relatively inexpensive and stable, there are almost no problems of by-products, and it is necessary to attach a large-scale device Oxygen Absorber Using Sponge Metal (Raney Catalyst) Produced by Elution and Removal of Part of Aluminum from Aluminum / Iron Alloy or Aluminum / Nickel Alloy (Patent Document 6).

Further, an oxygen-absorbing resin composition obtained by melting and kneading a Raney catalyst in a thermoplastic resin, and a multilayer body and hollow container obtained by molding the oxygen-absorbing resin composition, even in an atmosphere with little or no moisture It was found that it has the ability to absorb high oxygen and reported earlier (Patent Document 7).

  On the other hand, the Raney catalyst is usually stored as a slurry together with water in order to avoid reaction with oxygen in the atmosphere. Moreover, since it is a porous particle, it is easy to retain moisture in the pores. For this reason, there exists a problem that much water | moisture content remains in the oxygen absorptive resin composition produced by melt-kneading a Raney catalyst with a thermoplastic resin.

When a large amount of moisture remains in the oxygen-absorbing resin composition, when applied to articles that dislike the presence of water, such as pharmaceuticals or dried foods, metal products, organic EL elements, etc., the atmosphere in the sealed container may be kept under low humidity conditions. There was a problem because a trace amount of water was released from the oxygen-absorbing resin composition. For this reason, an oxygen-absorbing resin composition having an ability to absorb oxygen in the atmosphere even in an atmosphere having little or no moisture and having a small amount of moisture to be retained is desired.

Japanese Patent No. 4001614 Japanese Patent No. 4248986 Japanese Patent Laid-Open No. 62-277148 Japanese Patent No. 3496427 International Publication No. 2010/147097 International Publication No. 2012/105457 International Publication No. 2013/073590

  The present inventors have found that the metal in which only aluminum is removed using an aqueous solution of sodium hydroxide from an alloy of aluminum and iron or an alloy of aluminum and nickel is 30% RH (25 ° C.) or less. It has been found that oxygen in the atmosphere can be absorbed and removed at a level equivalent to that of a conventional oxygen scavenger, even in an atmosphere with little or no oxygen. As a result of further studies, the alloy used is a specific type of transition metal (in the range of component (A)) and one selected from the group consisting of aluminum, zinc, tin, lead, magnesium and silicon ( Can be used as long as it is an alloy containing the component (B), and at least part of the component (B) is eluted (leached) from the alloy by being subjected to an aqueous solution treatment with acid or alkali. By doing so, it was found that an oxygen absorbent composed of the target metal can be obtained. And the manufacturing apparatus which has the process of removing part or all of the water in a raw material as liquid water, such as the twin screw extruder which has a dehydration slit or a vent stuffer, and removing the remainder to remove as water vapor | steam Thus, it was found that an oxygen-absorbing resin composition containing a small amount of water containing the oxygen absorbent can be obtained. Furthermore, the oxygen-absorbing resin composition and the storage of articles in which the oxygen-absorbing film or oxygen-absorbing sheet using the oxygen-absorbing resin composition does not like the presence of water such as pharmaceuticals, dried foods, metal products, organic EL devices It was found that it can be suitably used. The present invention is based on these findings.

  Therefore, the present invention provides an oxygen-absorbing resin composition having an ability to absorb oxygen in the atmosphere even in an atmosphere with little or no moisture, and the raw material is relatively inexpensive and stable. Providing an oxygen-absorbing resin composition that has almost no biological problems and does not require a large-scale device such as hydrogen reduction, and further contains less water With the goal. Another object of the present invention is to provide an oxygen-absorbing film or oxygen-absorbing sheet using such an oxygen-absorbing resin composition.

That is, according to the present invention, the following inventions (1) to (7) are provided.
(1) (I) (A) An alloy containing at least one transition metal selected from the group consisting of iron, cobalt, nickel, and copper, and (B) aluminum is subjected to an alkaline aqueous treatment, BET method of a metal obtained by eluting and removing at least a part of the component (B) (metal of (I)) An oxygen-absorbing resin composition comprising an oxygen absorbent having a specific surface area of 10 m ² / g and (II) a thermoplastic resin, and having a moisture content of 5000 ppm or less.
(2) The oxygen-absorbing resin composition makes the metal (I) a metal slurry (III) containing water so that the oxygen in the atmosphere and the metal (I) do not come into contact with water. A step of removing the water contained in the metal slurry (III) as liquid and / or gaseous water while melt-kneading the metal slurry (III) with the thermoplastic resin (II). The oxygen-absorbing resin composition according to (1), which is produced by a method comprising a step of replacing the thermoplastic resin (II).
(3) The oxygen-absorbing resin composition according to (2) above, wherein in the step of replacing the water and the thermoplastic resin (II), a twin-screw extruder having a dehydration slit and / or a vent stuffer is used. (4) The oxygen-absorbing resin composition according to any one of (1) to (3), comprising a dehydrating agent (IV).
(5) The dehydrating agent (IV) according to any one of (1) to (4), wherein the dehydrating agent (IV) is one or more selected from the group consisting of calcium oxide, calcium chloride, magnesium chloride, and zeolite. An oxygen-absorbing resin composition.
(6) An oxygen-absorbing film or oxygen-absorbing sheet comprising the oxygen-absorbing resin composition according to the above (1) to (5) and having a film shape or sheet shape.
(7) Using the oxygen-absorbing resin composition according to any one of (1) to (5) above or the oxygen-absorbing film or oxygen-absorbing sheet according to (6) above, A storage method for storing articles.

  The oxygen-absorbing resin composition according to the present invention has oxygen in the atmosphere at a level equivalent to that of an oxygen-absorbing resin composition containing a conventional oxygen scavenger, even in an atmosphere with little or no moisture. It can be absorbed and removed. In addition, the amount of moisture contained in the oxygen-absorbing resin composition is small, and the retained moisture is hardly released to the outside. Therefore, it can also be suitably used for applications such as deoxidizing the atmosphere of dry foods, pharmaceuticals, electronic materials, and organic EL element packages that dislike moisture, which has been difficult to apply to conventional oxygen scavengers.

Oxygen-absorbing resin composition The oxygen-absorbing resin composition according to the present invention comprises (I) an oxygen absorbent and (II) a thermoplastic resin. Here, the oxygen absorptivity means that oxygen can be selectively absorbed from the ambient atmosphere where the resin composition is installed.

Oxygen Absorber The oxygen absorbent used in the present invention is composed of the following two components: (A) at least one transition metal selected from the group consisting of manganese group, iron group, platinum group and copper group; B) An alloy containing at least one selected from the group consisting of amphoteric metals, magnesium and silicon is subjected to an acid or alkali aqueous solution treatment, and at least part of the component (B) is eluted and removed. It is made of a metal that can be used. In the present specification, the “oxygen absorber” refers to an agent that can selectively absorb oxygen from the ambient atmosphere in which the agent is installed.

(I) Metal “(I) Metal” contained in the oxygen-absorbing resin composition of the present invention is as described above.
(A) at least one transition metal selected from the group consisting of manganese group, iron group, platinum group and copper group;
(B) An alloy containing at least one selected from the group consisting of aluminum, zinc, tin, lead, magnesium and silicon is subjected to an acid or alkali aqueous solution treatment, and at least a part of the component (B) Is obtained by elution removal.

Ingredient (A)
Transition metals that can be used as the component (A) constituting the oxygen absorber are manganese group (manganese, technetium, rhenium), iron group (iron, cobalt, nickel), platinum group (ruthenium, rhodium, palladium, osmium, iridium). , Platinum) or a copper group (copper, silver, gold). For this reason, you may use combining 2 or more types, for example, when iron and nickel are selected, you may use a Fe-Ni alloy as a component (A).

  The component (A) is preferably manganese, iron, cobalt, nickel, or copper, more preferably iron, cobalt, nickel, or copper, still more preferably iron, nickel, Preferably, it is iron. Among these, iron is preferable because it is safe and inexpensive.

Ingredient (B)
The component (B) constituting the oxygen absorbent is at least one selected from aluminum, zinc, tin, lead, magnesium and silicon. Component (B) is preferably one or more selected from aluminum, zinc, magnesium or silicon, more preferably aluminum, zinc, magnesium or silicon, and still more preferably aluminum. Of these, aluminum is preferable because it is inexpensive.

Ingredient (C)
In the present invention, an alloy containing the component (A) and the component (B) is prepared. At this time, molybdenum, chromium, titanium, vanadium, tungsten, or the like may be further added to the alloy as an additive metal. . It may further contain additional components such as cyanic acids.

  In the present invention, an alloy containing the component (A) and the component (B) is prepared by a melting method. At this time, the composition ratio (component (A): component (B)) of the component (A) and the component (B) in the alloy is preferably 20:80 to 80:20, more preferably 30:70 to 70:30. As a more specific example, when the component (A) is iron or nickel and the component (B) is aluminum, the total amount of the component (A) and the component (B) is 100 parts by mass of iron or nickel. The proportion is preferably 30 to 55 parts by mass, and the proportion of aluminum is preferably 45 to 70 parts by mass.

  The obtained alloy may be directly subjected to an acid or alkali aqueous solution treatment, but is usually subjected to an acid or alkali aqueous solution treatment after being finely pulverized. In the present specification, “alloy” means not only a single composition having a specific crystal structure but also a mixture thereof and a mixture of metals themselves.

  As a method for finely pulverizing the alloy, a conventional method for crushing and pulverizing metals can be used as appropriate, for example, pulverizing with a jaw crusher, a roll crusher, a hammer mill, etc. It can be finely pulverized with a ball mill. Alternatively, the molten alloy may be pulverized by a rapid solidification method such as an atomizing method. Here, when the atomizing method is used, it is preferably performed in an inert gas such as an argon gas. As the atomizing method, for example, the method described in JP-A-5-23597 can be used.

  The particle size of the obtained alloy powder is preferably in the range of 5 to 200 μm, and the particle size distribution is preferably as narrow as possible. From the viewpoint of eliminating particles having a large particle size or aligning the particle size distribution, sieving (classification) may be appropriately performed using a commercially available mesh sieve (for example, a 200 mesh sieve). In the case of the atomizing method, the powder tends to be nearly spherical and the particle size distribution tends to be narrow.

In the present invention, the obtained alloy or alloy powder is subjected to an acid or alkali aqueous solution treatment to elute and remove at least part of the component (B) from the alloy. That is, in this invention, the metal obtained after eluting and removing at least one part of a component (B) from an alloy is used. The aqueous solution of acid or alkali used here is one that does not dissolve or hardly dissolve component (A), but can dissolve and remove component (B), that is, component (B) from the alloy. There is no particular limitation as long as it can be leached, and any of them can be used. Examples of the acid in the acid aqueous solution include hydrochloric acid, sulfuric acid, and nitric acid. Examples of the alkali in the alkali aqueous solution include sodium hydroxide, potassium hydroxide, Na ₂ CO ₃ , K ₂ CO ₃ , and ammonia. Etc. can be used. About these acid and alkali aqueous solution, you may use it in combination of 2 or more type as needed.

  According to a preferred embodiment of the present invention, the acid or alkali aqueous solution is an alkaline aqueous solution, more preferably a sodium hydroxide aqueous solution. For example, when aluminum is used as the component (B), when sodium hydroxide is used as the alkaline aqueous solution, excess sodium hydroxide can be easily removed by washing with water, and the eluted aluminum can be easily removed. The effect of reducing the number of washings can be expected.

  In the aqueous solution treatment of acid or alkali, usually, if it is an alloy powder, the alloy powder is gradually added to the above aqueous solution while stirring, but the alloy powder is put in water and concentrated acid or alkali is added here. May be dropped.

  In the acid or alkali aqueous solution treatment, the concentration of the acid or alkali aqueous solution used is, for example, 5 to 60% by mass, and more specifically, for example, 10 to 40% by mass in the case of sodium hydroxide.

  In the acid or alkali aqueous solution treatment, the temperature of the aqueous solution is preferably heated to about 20 to 120 ° C., for example. Preferably, the temperature of the alkaline aqueous solution is 25 to 100 ° C.

  The treatment time for which the alloy or alloy powder is subjected to the acid or alkali aqueous solution treatment may vary depending on the shape and state of the alloy used, the amount thereof, the concentration of the acid or alkali aqueous solution, the temperature during the treatment, etc. Usually, it may be about 30 to 300 minutes. By adjusting the treatment time, the elution amount of the component (B) from the alloy can be adjusted.

  In the present invention, at least a part of the component (B) is eluted and removed from the alloy by treatment with an aqueous solution of acid or alkali. Here, “leaving and removing at least a part of the component (B)” means to elute and remove a part of the component (B) from the alloy containing the component (A) and the component (B), It also includes the case where all of component (B) is eluted and removed from the alloy. In the elution process, the possibility that a part of the component (A) is dissolved as a result cannot be denied. Therefore, the “at least part of the component (B)” includes an aqueous solution containing only the component (B) as an acid or an alkali. There is no need to interpret it only when it is eluted by processing.

  By the aqueous solution treatment with acid or alkali, at least a part, preferably most of the component (B) (for example, aluminum) is eluted from the alloy. The elution ratio of the component (B) from the alloy can be indicated by the content (mass basis) (residual rate) of the component (B) in the metal obtained by elution removal.

  In the metal (I) used as the oxygen absorbent, the content of the component (B) is preferably 0.1 to 50% by mass, more preferably 1 to 40% by mass. More specifically, for example, when the alloy is an Al—Fe alloy, the aluminum content in the metal obtained by elution and removal of aluminum by treatment with an aqueous solution of acid or alkali is preferably 0.1 to 50% by mass. More preferably, it is 1-40 mass%. In addition, the content rate of the component (B) (for example, aluminum) in the metal of (I) contained in an oxygen absorptive resin composition can be measured by ICP method, for example.

The metal (I) obtained as described above has a porous shape (or a porous body). Here, the porous shape means a state having a large number of pores on the surface and inside that can be confirmed with an electron microscope. In the present invention, the degree of the porous shape of the metal can be expressed by its specific surface area. Specifically, the specific surface area by the BET method of the metal used in the oxygen-absorbing resin composition according to the present invention is at least 10 m ² / g, preferably at least 20 m ² / g.

For example, in the present invention, when iron is used as the component (A) and aluminum is used as the component (B), the specific surface area (by the BET method) of the obtained porous metal is, for example, 20 to 40 m ^2. In the case of normal iron powder (reduced iron powder or atomized iron powder) that is not porous, the specific surface area is about 0.07 to 0.13 m ² / g, and is porous. It is clear whether there is.

Moreover, the degree of the porous shape which a metal has can also be represented by a bulk density. The bulk density of the metal (I) used as the oxygen absorbent is 2 g / cm ³ or less, preferably 1.5 g / cm ³ or less. Incidentally, in the case of normal iron powder (reduced iron powder or atomized iron powder) that is not porous, the bulk density is greater than 2 and about ³ g / cm ³ or less.

  In the present invention, when iron is used as the component (A) and aluminum is used as the component (B), the average particle size of the obtained porous metal powder (I) is usually 1 to 1,000 μm. The thickness is preferably 10 to 500 μm. In the present specification, the “average particle size” is a value calculated from the particle size distribution obtained by measuring the particle size by the laser diffraction method, for example, a laser diffraction scattering type particle size distribution measuring device (manufactured by Seishin Enterprise Co., Ltd.). SK laser micron sizer LMS-2000e) can be used for measurement.

  Since the porous metal (I) used as an oxygen absorbent has a high oxygen absorption activity, it is an atmosphere under a low humidity condition (for example, a condition of 30% RH (relative humidity) (25 ° C.) or lower). Even if it is below, the performance as an oxygen absorber can be exhibited suitably.

  The oxygen absorbent contained in the oxygen-absorbing resin composition according to the present invention absorbs oxygen even in a low humidity atmosphere of 30% RH (25 ° C.) or less. More specifically, in a low humidity atmosphere of 30% RH (relative humidity) (25 ° C.) or less, the metal of (I) used as an oxygen absorbent is at least 5 mL / g oxygen, more preferably 10 mL / g oxygen. To absorb. The oxygen absorption amount of the metal (I) can be, for example, 5 to 150 mL / g in a low humidity atmosphere of 30% RH (relative humidity) (25 ° C.) or less.

Metal slurry (III)
The metal (I) used as an oxygen absorbent usually reacts immediately with oxygen in the atmosphere in the air, and the oxygen absorption performance is lowered. Therefore, before using the metal of (I), it is necessary to avoid oxygen as much as possible. Usually, the metal of (I) is preserve | saved in water, and it can protect so that it may not contact with oxygen in atmosphere by setting it as the slurry (metal slurry (III)) containing the metal of (I) and water.

 The amount of water contained in the metal slurry (III) is preferably 10 to 90% by mass, more preferably 10 to 80% by mass, particularly 20 to 70% by mass. If the amount of the dispersion medium contained in the slurry is too small, the surface of (I) cannot be completely covered with water and may react with oxygen in the atmosphere, while the water content is too high. Then, it becomes difficult to remove water at a time, and it is necessary to remove water in a plurality of steps, which complicates the process.

(II) Thermoplastic resin (II) The thermoplastic resin is not particularly limited as long as the effects of the present invention are not essentially impaired, and a conventionally known thermoplastic resin can be used. For example, the thermoplastic resin is preferably at least one selected from the group consisting of polyolefin resin, polyester resin, polyamide resin, polyvinyl alcohol resin, ethylene vinyl alcohol copolymer resin, and chlorine resin.

As the polyolefin resin, a conventionally known polyolefin resin can be used.
For example, various polyethylenes (PE) such as high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, ultra low density polyethylene, polyethylene by metallocene catalyst, polystyrene, polymethylpentene, propylene homopolymer, propylene -Polypropylenes, such as an ethylene block copolymer and a propylene-ethylene random copolymer, may be used alone or in combination. Due to oxygen absorption performance and film processability, polyolefin resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, various polyethylenes such as polyethylene using a metallocene catalyst, and propylene-ethylene block copolymers. Various polypropylenes such as propylene-ethylene random copolymer are particularly preferably used. These polyolefin resins include ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, if necessary. A polymer, an ethylene-methyl methacrylate copolymer, or a thermoplastic elastomer may be added.

  A conventionally known polyester resin can be used as the polyester resin. For example, aromatic polyester and aliphatic polyester can be mentioned, and specifically, polyethylene terephthalate (PET) can be mentioned.

  As the polyamide resin, a conventionally known polyamide resin can be used. Examples include aromatic polyamides and aliphatic polyamides. Specifically, nylon-6, nylon-6,6, nylon-6,12, polymetaxylylene adipamide (for example, MX nylon manufactured by Mitsubishi Gas Chemical Co., Ltd.) And the like.

  A conventionally known polyvinyl alcohol resin can be used as the polyvinyl alcohol resin. The polyvinyl alcohol resin is a resin obtained by saponifying a vinyl ester polymer or a copolymer of a vinyl ester and another monomer using an alkali catalyst. The saponification degree of the vinyl ester component of the polyvinyl alcohol resin is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more. The polyvinyl alcohol resin may be a blend of two or more types of polyvinyl alcohol resins having different degrees of saponification.

  As the ethylene vinyl alcohol copolymer resin (EVOH), a conventionally known ethylene vinyl alcohol copolymer resin can be used. The ethylene-vinyl alcohol copolymer resin is a resin obtained by saponifying an ethylene-vinyl ester copolymer. Among them, an ethylene-vinyl alcohol copolymer having an ethylene content of 5 to 60 mol% and a saponification degree of 85% or more is preferable. The lower limit of the ethylene content of the ethylene-vinyl alcohol copolymer resin is preferably 20 mol% or more, more preferably 25 mol% or more. The upper limit of the ethylene content is preferably 55 mol% or less, more preferably 50 mol%. The saponification degree of the vinyl ester component is preferably 85% or more, more preferably 90% or more, and still more preferably 99% or more.

  A conventionally well-known chlorine resin can be used as a chlorine resin. For example, a block copolymer, a graft copolymer mainly composed of polyvinyl chloride or polyvinylidene chloride (PVDC), and a polymer blend mainly composed of vinyl chloride resin can be mentioned. Examples of comonomers copolymerized with vinyl chloride include vinyl acetate, vinylidene chloride, acrylic acid, methacrylic acid and esters thereof, acrylonitriles, olefins such as ethylene and propylene, maleic acid and anhydrides thereof, etc. Can do.

  Among the above thermoplastic resins, in view of oxygen absorption, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, elastomer, or a mixture thereof is preferably used.

  As long as the effect of the present invention is not essentially impaired, the thermoplastic resin includes a dispersant such as a wax and a surfactant, a color pigment such as titanium oxide, an antioxidant, a slip agent, an antistatic agent, and a stabilizer. Additives, fillers such as calcium carbonate, clay, mica, silica, desiccants, deodorants, phenolic antioxidants, phosphorus antioxidants, lactone antioxidants, flame retardants, light stabilizers, UV absorbers Optional components such as an agent, a lubricant, a deodorizing agent, an antistatic agent, an anti-tacking agent, an antifogging agent, and a surface treatment agent can be blended. In particular, it is preferable to add a dispersant in order to improve the dispersion of the oxygen absorbent. Moreover, in order to recycle and reprocess the offcuts generated during production, it is preferable to add an antioxidant. A blending method is not particularly limited, but is generally melt kneaded with a resin.

Production and Use of Oxygen Absorbing Resin Composition In the present invention, an oxygen absorbing resin composition can be prepared by mixing (I) an oxygen absorbent and (II) a thermoplastic resin. At this time, the concentration of the metal (I) in the oxygen-absorbing resin composition is 1 to 80% by mass, preferably 5 to 70% by mass, and particularly preferably 10 to 65% by mass. Is preferred. When the metal concentration is in the above range, there is an advantage that a higher oxygen absorption performance can be obtained compared to the case where the amount of added metal is small, and the total amount accompanying the increase in the metal content compared to the case where the amount of added metal is too large. Since the increase in viscosity can be suppressed, the resin processability can be maintained well.

  The water content of the oxygen-absorbing resin composition of the present invention is 5000 ppm or less, preferably 3000 ppm or less, more preferably 1000 ppm or less, and particularly preferably 500 ppm or less. When the moisture content is less than or equal to the above preferable value, it is difficult for moisture to migrate out of the oxygen-absorbing resin composition, which is advantageous for storage of articles that dislike moisture. The amount of water transferred to the outside of the oxygen-absorbing resin composition tends to decrease with a decrease in the amount of water contained in the oxygen-absorbing resin composition, and it is preferable to reduce the amount of water contained as much as possible. In the present specification, the “water content” of the oxygen-absorbing resin composition means that the water content of the oxygen-absorbing resin composition heated to 185 ° C. is measured by a coulometric method, and the obtained water content is measured. It is a value expressed as a weight ratio with the oxygen-absorbing resin composition used, and is measured at a measurement temperature of 185 ° C. using, for example, a desktop coulometric moisture meter (CA-200, manufactured by Mitsubishi Chemical Analytech Co., Ltd.). can do.

There is no particular limitation on the method of setting the moisture content of the oxygen-absorbing resin composition to 5000 ppm or less.
1) A method of heating and drying the metal slurry (III) to obtain a dried metal (I) and then melt-kneading it with the thermoplastic resin (II). 2) A metal slurry (III) and a thermoplastic resin (II). 3) A method of removing all of the water removed from the metal slurry (III) as water vapor when the metal slurry (III) is melt-kneaded. 3) When the metal slurry (III) and the thermoplastic resin (II) are melt-kneaded, the metal slurry ( III) Method for removing part or all of the water contained in liquid as liquid water and removing the remaining water to be removed as water vapor 4) Heating the oxygen-absorbing resin composition having a water content of 5000 ppm or more, It is preferable to carry out a method such as a method of removing moisture by drying, and these methods can be carried out alone or in combination.

  1) The method for drying the metal slurry (III) is not particularly limited, and a known apparatus such as a box-type vacuum dryer, a nauter mixer, a conical dryer, a drum dryer, or a spray dryer can be used. There is no particular limitation on the method of melt-kneading the dried metal (I) and the thermoplastic resin (II). For example, a kneader, a Banbury mixer, a planetary mixer, a butterfly mixer, a single-screw or multi-screw extruder, etc. The metal (I) and the thermoplastic resin (II) can be melt-kneaded using a known stirring or kneading apparatus equipped with a heating device such as the above. In this method, at least a manufacturing step including a step of drying the metal slurry (III) and a step of melting and kneading the metal of (I) and the thermoplastic resin (II) is necessary, and the manufacturing apparatus becomes large. Further, since the dried (I) metal is produced, there is a concern that heat is generated when the dried (I) metal comes into contact with oxygen in the atmosphere. In order to prevent heat generation of the metal of (I), the manufacturing process including the step of drying the metal slurry (III) and the step of melt-kneading the metal of (I) and the thermoplastic resin (II), the metal of (I) In order to avoid contact between oxygen and oxygen, it is necessary to carry out under an inert gas atmosphere or under reduced pressure. For this reason, there are many problems from the viewpoint of ensuring economy and safety.

  2) When the metal slurry (III) and the thermoplastic resin (II) are melt-kneaded, there is no particular limitation on the method for removing all water removed from the metal slurry (III) as water vapor. Using a known stirring or kneading device equipped with a heating device such as a Banbury mixer, planetary mixer, butterfly mixer or a single-screw or multi-screw extruder, all water removed from the metal slurry (III) is steamed. And the metal of (I) and the thermoplastic resin (II) can be melt-kneaded. In order to remove water more efficiently in this method, the stirring or kneading apparatus equipped with a heating device is preferably equipped with a devolatilizing means. For example, when melt kneading is performed using a screw extruder, a vent type extruder having a vent in a part of the barrel of the screw extruder can be suitably used. The vent may be a devolatilizing vent connected to a vacuum pump for efficient water removal. In this method, unlike the method 1), the water in the metal slurry (III) is replaced with the thermoplastic resin (II) before the dried metal (I) is formed. It is preferable from the viewpoint of safety because contact with oxygen in the inside can be prevented. However, when all of the water removed from the metal slurry (III) is removed as water vapor when the metal slurry (III) and the thermoplastic resin (II) are melt-kneaded, only a huge amount of energy is required. In order to sufficiently reduce the amount of water contained in the oxygen-absorbing resin composition, it is necessary to extend the heating time, and there is a concern about deterioration of the thermoplastic resin (II) exposed to a high temperature for a long time. In the case of an apparatus, there are many problems such as an increase in the size of the apparatus.

  3) When the metal slurry (III) and the thermoplastic resin (II) are melt-kneaded, part or all of the water contained in the metal slurry (III) is removed as liquid water, and the remaining water to be removed is removed. Examples of the method for removing the water vapor include a twin screw extruder having a dehydration slit in a part of the barrel of the twin screw extruder and a twin screw extruder having a vent stuffer connected to a part of the barrel. Part or all of the water contained in the metal slurry (III) can be liquidized by connecting a vent stuffer to a twin screw extruder or a part of the barrel equipped with a dewatering slit in a part of the barrel of the twin screw extruder. Can be removed as water. This method is preferable from the viewpoint of safety because it can prevent the metal (I) from contacting with oxygen in the atmosphere in the same manner as the method 2). In addition, since part or all of the water contained in the metal slurry (III) is removed as liquid water, less energy is required to remove the water and the heating time can be shortened compared with the method 2). Since the deterioration of the thermoplastic resin (II) can be prevented, it is preferable. In this method, the water contained in the metal slurry (III) is removed as liquid water, and the remaining water to be removed is removed as water vapor, for example, in a twin-screw extruder equipped with a dewatering slit or a vent stuffer. In some cases, a vented extruder equipped with a vent in a part of the barrel on the downstream side of the dewatering slit or vent stuffer can be suitably used. The vent may be a devolatilizing vent connected to a vacuum pump for efficient water removal.

  4) As a method for removing moisture by heating and drying an oxygen-absorbing resin composition having a water content of 5000 ppm or more, pellets of the oxygen-absorbing resin composition produced by the methods 1) to 3) above Alternatively, the water content of the oxygen-absorbing resin composition can be reduced by heating the powder under reduced pressure or in an inert gas. However, in order to maintain the shape of the oxygen-absorbing resin composition in pellets or powder, it is preferable that the temperature is at least 10 ° C. lower than the melting point of the thermoplastic resin (II) contained in the oxygen-absorbing resin composition. In order to sufficiently reduce the amount of water contained in the oxygen-absorbing resin composition, the heating time becomes long, the production rate of the oxygen-absorbing resin composition is lowered, and there is a problem from an economical viewpoint.

  In the present invention, it is preferable to add a dehydrating agent (IV) in the oxygen-absorbing resin composition in order to reduce the amount of water transferred from the oxygen-absorbing resin composition to the outside of the oxygen-absorbing resin composition.

The dehydrating agent (IV) contained in the oxygen-absorbing resin composition of the present invention is preferably one that chemically adsorbs moisture and can maintain a solid state even after moisture adsorption. For example, alkali metal oxides such as sodium oxide and potassium oxide, alkaline earth metal oxides such as magnesium oxide, calcium oxide, strontium oxide and barium oxide, sulfates such as sodium sulfate, magnesium sulfate and calcium sulfate, calcium chloride, Examples thereof include metal halides such as magnesium chloride and iron chloride. The dehydrating agent (IV) may be used alone, or one or a mixture of two or more may be used. In addition to these, metal alkoxides such as aluminum trioctyl oxide and aluminum oxide 2-ethylhexanoate can also be used as the dehydrating agent (IV) of the present invention.

  In the present invention, when (I) an oxygen absorbent and (II) a thermoplastic resin are mixed to prepare an oxygen absorbent resin composition, various additives are added within a range that does not impair the resin characteristics. For example, plasticizers, UV stabilizers, anti-coloring agents, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, mold release agents, antioxidants, coloring pigments, etc. are added. can do. These additives are preferably added in the range of 0.01 to 20% by mass with respect to the thermoplastic resin (II).

  In the present invention, when preparing an oxygen-absorbing resin composition by mixing (I) an oxygen absorbent and (II) a thermoplastic resin, under an inert gas atmosphere such as nitrogen or argon or under reduced pressure. Preferably it is done. By performing melt-kneading in a low oxygen concentration state, it is possible to suppress the deterioration of the reaction due to the contact of oxygen with the metal of (I) and to suppress the thermoplastic resin from being oxidized by oxygen. it can. For example, melt kneading is preferably performed in a low oxygen concentration environment where the oxygen partial pressure is 10 kPa or less, more preferably 5 kPa or less, and even more preferably 1 kPa or less.

  The form of the oxygen-absorbing resin composition of the present invention is not particularly limited, and can be used in various forms such as a film form, a sheet form, a pellet form, and a powder form. There are no restrictions on the shape of the pellets and powder. Among these, the shape of a sheet, film or powder is preferable because the surface area per unit mass is increased and the oxygen absorption rate can be improved. The thickness of the film is usually 10 μm or more and less than 250 μm, and the thickness of the sheet is usually 250 μm or more and less than 3 mm. The average particle diameter of the powder is usually 1 to 1,000 μm, preferably 10 to 500 μm.

  The form of the oxygen-absorbing resin composition of the present invention is not particularly limited. For example, all of various packaging forms such as a pouch, a container lid, a tray, a cup, a laminated tube container, a paper container, a bottle, or a blister container. Or it can be used as a part.

  The method for making the oxygen-absorbing resin composition of the present invention into a desired shape is not particularly limited, and a conventionally known method can be adopted. In the case of a sheet or a film, it can be formed by, for example, forming by a solution casting method, or by extrusion through a die having a predetermined shape such as a T-die or a circular die using a single-screw or multi-screw melt extruder. Of course, a compression molding method, an injection molding method, or the like can be employed. In the case of powder, for example, a powdery oxygen absorbent is obtained by pulverizing the oxygen-absorbing resin composition in a temperature atmosphere lower than Tg of the thermoplastic resin contained in the oxygen-absorbing resin composition. be able to. In the case of a pellet, for example, it can be obtained by pelletizing a strand discharged from an extruder. In particular, fine pellets can be obtained by thinning the strands. By filling the obtained powder or pellet into a sachet or canister, a sachet or canister-like oxygen absorbent can be obtained. Furthermore, it can be formed into a desired shape using a blow molding method, an injection molding method, a vacuum molding method, a pressure forming method, a stretch molding method, a plug assist molding method, and a powder molding method.

  According to another aspect of the present invention, an oxygen-absorbing material obtained by packaging a pellet, powder, sheet, or film-shaped oxygen-absorbing resin composition with a packaging material using all or part of a breathable packaging material. A package is provided. Here, as the packaging material, two breathable packaging materials are bonded together to form a bag, or one breathable packaging material and one non-breathable packaging material are bonded together to form a bag. What was made into a bag shape by bend | folding one breathable packaging material and sealing edges except a bending part. Further, as the breathable packaging material, a packaging material that transmits oxygen can be selected. As the breathable packaging material, paper or non-woven fabric, or a plastic film provided with breathability can be used.

The oxygen-absorbing resin composition according to the present invention is applicable from a region having a high water activity to a region having a low water activity. Thereby, it can apply suitably to the articles | goods with which water activity is low and the preservation | save on the dry conditions of low humidity is required. The water activity is a scale indicating the free water content in an article, and is represented by a number from 0 to 1, with 0 for an article without moisture and 1 for pure water. That is, the water activity Aw of a certain article is expressed as follows: the water vapor pressure in the space after the article is sealed and reached an equilibrium state is P, the water vapor pressure of pure water is P ₀ , and the relative humidity in the space is RH (%). , And
Aw = P / P ₀ = RH / 100
Is defined.

  In order to store low moisture content articles that need to be stored at low humidity, the relative humidity (RH) of the atmosphere in which the low moisture content articles are stored is preferably 0-70% RH, more preferably 0-50% RH. And particularly preferably 0 to 30% RH. In particular, the present invention can be applied to low-moisture-containing articles (packaged products) such as powdered and granular foods: (powder soup, powdered beverage, powdered confectionery, seasoning, cereal flour, nutritional food, health food, colorant, flavoring, Spices), powder, granular chemicals: (powdered powder, soap powder, toothpaste, industrial chemicals), molded products (tablet type) of these products, foods and chemicals that do not like the increase in moisture and need to avoid contamination It can be illustrated.

  Furthermore, since the oxygen-absorbing resin composition of the present invention can absorb oxygen regardless of the presence or absence of moisture in the object to be stored, powder seasonings, powdered coffee, coffee beans, rice, tea, beans, rice cakes, It can be suitably used for dried foods such as rice crackers, health foods such as pharmaceuticals and vitamins, electronic materials, organic EL devices and the like.

  According to another aspect of the present invention, the sheet or film-shaped oxygen-absorbing resin composition of the present invention, or the oxygen-absorbing resin composition in the form of pellets or powder, and all or part of the breathable packaging material. An article storage method is provided in which an object to be stored is sealed together with an oxygen absorbing packaged body packaged by the packaging material used in the above, and the object to be stored is deoxygenated and stored. According to still another preferred aspect of the present invention, the article to be stored is sealed inside the oxygen-absorbing resin composition in the form of a sheet or film of the present invention, and the article to be stored is deoxygenated and stored. A storage method is provided.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

Example 1
Al (aluminum) powder and Fe (iron) powder were mixed in proportions of 45 wt% and 55 wt%, respectively, and dissolved in nitrogen to obtain an Al—Fe alloy. The obtained Al—Fe alloy was pulverized using a jaw crusher, a roll crusher and a ball mill, and the pulverized product was classified using a 180 mesh (0.091 mm) mesh to obtain an Al—Fe alloy of 180 mesh or less. It was. After 350 g of the obtained Al—Fe alloy powder was stirred and mixed in a 30 wt% aqueous sodium hydroxide solution at 55 ° C. for 1 hour and 30 minutes, the mixed solution was allowed to stand and the upper layer liquid was removed. The remaining precipitate was washed with distilled water until the pH became 10 or less to obtain an Al—Fe porous metal powder.
Therefore, the porous metal powder was obtained by reaction in an aqueous solution to avoid contact with oxygen.

The obtained porous metal powder was vacuum-dried at 200 Pa or less and 100 ° C. to a moisture content of 1% by weight or less to obtain a dried Al—Fe porous metal powder (hereinafter referred to as “Al-Fe porous metal powder dried product” Metal powder 1 ”)) was obtained. The bulk density of the obtained metal powder 1 was 1.3 g / cm ³ (measured according to JIS Z2504). 1 g of this is packed in a breathable sachet, placed in a gas barrier bag (Al foil laminated plastic bag) with a desiccant, filled with 750 mL of air (oxygen concentration 20.9%), sealed and sealed at 25 ° C for 1 day. saved.

  As a result of measuring the oxygen concentration in the gas barrier bag stored at 25 ° C. for one day by gas chromatography, the oxygen concentration in the gas barrier bag was 11.2%, and the oxygen absorption amount was calculated from the reduced oxygen concentration in the gas barrier bag. As a result, the oxygen absorption amount was 81.9 mL / g.

  As a result of measuring the average particle size of the metal powder 1 using a particle size / shape distribution measuring instrument (“PITA-2” manufactured by Seishin Enterprise Co., Ltd.), the average particle size of the metal powder 1 was 43 μm.

As a result of measuring the specific surface area of the metal powder 1 using an automatic specific surface area measuring apparatus (“Gemini VII2390” manufactured by Shimadzu Corporation), the specific surface area of the metal powder 1 was 44.0 m ² / g.

  The metal powder 1 obtained as described above was adjusted in the amount of distilled water to produce a slurry having a moisture content of 40 mass% (hereinafter referred to as “metal slurry A”).

  Metal slurry A and low-density polyethylene (Japan) using a biaxial co-rotating extruder (screw diameter 41 mm, L / D value 48) equipped with a main feeder, dewatering slit, vent, and devolatilization vent from the upstream side Available from polyethylene, MFR 1.5 g / 10 min (measured according to JIS K7210), hereinafter referred to as “LDPE”) was melt-kneaded. First, LDPE was charged using a main feeder, and metal slurry A was charged from a vent using a pump. The mass ratio of the two was charged into a twin-screw co-rotating extruder while being quantitatively determined so that LDPE: metal slurry A = 65: 35. At this time, the main feeder was handled at an oxygen concentration of 3% or less (measured with a new Cosmos oxygen detector) by nitrogen substitution. The pressure of the devolatilization vent during operation was 5 kPa or less. It was also confirmed that liquid water and water vapor were discharged from the dehydration slit during operation, and water vapor was discharged from the devolatilization vent.

Subsequently, the molten material dispersed in the LDPE in which the metal powder 1 is melted is extruded from a strand die, cooled and solidified in a water bath, made into a strand shape having an outer diameter of about 2 mm, cut with a pelletizer, and resin pellets 1 Got. At this time, strand breakage and foaming were not recognized, and the resin pellet 1 could be produced satisfactorily. The density of the obtained resin pellet 1 was 1.18 g / cm ³ . In the method of Example 1, the water contained in the metal slurry A was discharged smoothly, and the time taken to produce 10 kg of the resin pellet 1 was 15 minutes.

  The moisture content of the obtained resin pellet 1 was measured at a measurement temperature of 185 ° C. using a desktop coulometric method moisture meter (CA-200, manufactured by Mitsubishi Chemical Analytech Co., Ltd.). 490 ppm.

The resin pellet 1 obtained as described above was pressed under conditions of 150 ° C. and 300 kgf / cm ² in nitrogen using a press machine to obtain a resin film 1 having an average thickness of about 200 μm.

  What obtained by cutting out the obtained resin film 1 to 10 cm x 10 cm was used as the test piece. The weight of the test piece was 2.36 g, and the amount of metal powder 1 contained in the test piece was calculated from the blending ratio of LDPE and metal slurry A to be 0.58 g. The test piece was placed in a gas barrier bag (Al foil laminated plastic bag) together with a desiccant, filled with 150 mL of air (oxygen concentration 20.9%), sealed, and stored at 25 ° C. for 30 days.

  When the oxygen concentration in the gas barrier bag after storage was measured by gas chromatography, the oxygen concentration was 9.9 vol%, and the oxygen absorption amount was calculated from the reduced oxygen concentration in the gas barrier bag. The oxygen absorption amount per unit weight of the powder 1 was 31.8 mL / g.

Example 2
Using a twin-screw co-rotating extruder (screw diameter 41 mm, L / D value 48) equipped with a main feeder, vent stuffer, vent, and devolatilization vent from the upstream side, linear low density in the resin to be melt kneaded Metal slurry A and LLDPE were the same as in Example 1 except that polyethylene (manufactured by Nippon Polyethylene Co., Ltd., MFR 5.0 g / 10 min (measured according to JIS K7210), hereinafter referred to as “LLDPE”) was used. Was melt kneaded. It was confirmed that liquid water and water vapor were discharged from the vent stuffer during operation, and water vapor was discharged from the devolatilization vent.

Subsequently, the melt dispersed in the LLDPE in which the metal powder 1 is melted is extruded from a strand die, cooled and solidified in a water bath, made into a strand shape having an outer diameter of about 2 mm, cut with a pelletizer, and resin pellets 2 Got. At this time, no strand breakage or foaming was observed, and the resin pellet 2 could be produced satisfactorily. In the method of Example 2, the water contained in the metal slurry A was discharged smoothly, and the time taken to produce 10 kg of the resin pellet 2 was 20 minutes.

  When the moisture content of the obtained resin pellet 2 was measured at a measurement temperature of 185 ° C. using a desktop coulometric moisture meter (CA-200, manufactured by Mitsubishi Chemical Analytech Co., Ltd.), 870 ppm.

The resin pellet 2 obtained as described above was pressed under conditions of 180 ° C. and 350 kgf / cm ² in nitrogen using a press machine to obtain a resin film 2 having an average thickness of about 150 μm.

  The obtained resin film 2 cut into 10 cm × 10 cm was used as a test piece. The weight of the test piece was 1.80 g, and the amount of metal powder 1 contained in the test piece was calculated from the blending ratio of LLDPE and metal slurry A, and was 0.44 g. The test piece was placed in a gas barrier bag (Al foil laminated plastic bag) together with a desiccant, filled with 150 mL of air (oxygen concentration 20.9%), sealed, and stored at 25 ° C. for 30 days.

  When the oxygen concentration in the gas barrier bag after storage was measured by gas chromatography, the oxygen concentration was 13.5 vol%, and as a result of calculating the oxygen absorption amount from the reduced oxygen concentration in the gas barrier bag, the metal contained in the test piece The oxygen absorption amount per unit weight of the powder 1 was 29.2 mL / g.

Example 3
Metal slurry A and medium density polyethylene (manufactured by Prime Polymer Co., Ltd., MFR 50 g / 10 min (measured according to JIS K7210), hereinafter referred to as “MDPE”) using a trimix (tank volume 15 L). Melt kneaded. First, the metal slurry A and MDPE were introduced into a trimix tank so that the mass ratio of both was MDPE: metal slurry A = 50: 50, and the tank was decompressed and heated to be melt-kneaded. . After melt-kneading, a trimix tank is attached to the ram press, and the ram press is used to extrude the melt from the discharge port having an inner diameter of 25 mm at the bottom of the tank, to cool and solidify in a water bath, Obtained. It was confirmed that water was discharged as water vapor during operation. Moreover, it took time to sufficiently remove the water, and the time taken to obtain 10 kg of solidified product was about 3 hours.

  The rod-like solidified product was shaved to obtain a resin pellet 3 of about 3 mm square. When the moisture content of the obtained resin pellet 3 was measured in the same manner as in Example 1, it was 2080 ppm relative to the total amount of the resin pellet 3.

The resin pellet 3 obtained as described above was pressed under the conditions of 150 ° C. and 300 kgf / cm ² to obtain a resin film 3 having an average thickness of about 150 μm.

  The obtained resin film 3 cut into 10 cm × 10 cm was used as a test piece. The weight of the test piece was 2.15 g, and the amount of metal powder 1 contained in the test piece was calculated from the blending ratio of MDPE and metal slurry A, and was 0.80 g. The test piece was placed in a gas barrier bag (Al foil laminated plastic bag) together with a desiccant, filled with 150 mL of air (oxygen concentration 20.9%), sealed, and stored at 25 ° C. for 30 days.

  When the oxygen concentration in the gas barrier bag after storage was measured by gas chromatography, the oxygen concentration was 11.2 vol%, and the oxygen absorption amount was calculated from the reduced oxygen concentration in the gas barrier bag. As a result, the metal contained in the test piece The amount of oxygen absorbed per unit weight of Powder 1 was 20.4 mL / g.

Comparative Example 1
The metal slurry A and LDPE were prepared in the same manner as in Example 1 except that a main feeder from the upstream side and a biaxial co-rotating extruder equipped with two vents (screw diameter 37 mm, L / D value 40) were used. Melt kneaded. It was confirmed that vent steam during operation was discharged.

Subsequently, the melt dispersed in the LDPE in which the metal powder 1 is melted is extruded from a strand die, cooled and solidified in a water bath, formed into a strand shape having an outer diameter of about 2 mm, cut with a pelletizer, and resin pellets 4 Got. In the method of Comparative Example 1, the water contained in the metal slurry A was not sufficiently discharged, and the strands were severely foamed, resulting in frequent strand breakage. It took 30 minutes to produce 10 kg of resin pellets 4.

  When the moisture content of the obtained resin pellet 4 was measured at a measurement temperature of 185 ° C. using a desktop coulometric moisture meter (CA-200, manufactured by Mitsubishi Chemical Analytech Co., Ltd.), the total amount of the resin pellet 4 was measured. 7870 ppm.

The resin pellet 4 obtained as described above was pressed in nitrogen using a press machine at 150 ° C. and 300 kgf / cm ² to obtain a resin film 4 having an average thickness of about 200 μm.

  What obtained by cutting out the obtained resin film 1 to 10 cm x 10 cm was used as the test piece. The weight of the test piece was 2.36 g, and the amount of metal powder 1 contained in the test piece was calculated from the blending ratio of LDPE and metal slurry A to be 0.58 g. The test piece was placed in a gas barrier bag (Al foil laminated plastic bag) together with a desiccant, filled with 150 mL of air (oxygen concentration 20.9%), sealed, and stored at 25 ° C. for 30 days.

  When the oxygen concentration in the gas barrier bag after storage was measured by gas chromatography, the oxygen concentration was 16.0 vol%, and as a result of calculating the oxygen absorption amount from the reduced oxygen concentration in the gas barrier bag, the metal contained in the test piece The amount of oxygen absorbed per unit weight of Powder 1 was 15.2 mL / g.

Claims (7)

(I) (A) An alloy containing at least one transition metal selected from the group consisting of iron, cobalt, nickel, and copper, and (B) aluminum is subjected to an alkaline aqueous solution treatment, and the component ( B) a metal obtained by eluting and removing at least a part of (B), and a metal obtained by eluting and removing at least a part of the component (B). An oxygen-absorbing resin composition comprising an oxygen absorbent having a specific surface area of at least 10 m ² / g and (II) a thermoplastic resin and having a moisture content of 5000 ppm or less.   The oxygen-absorbing resin composition is a step of making the metal in (I) the metal slurry (III) containing water so that the oxygen in the atmosphere and the metal in (I) are not in contact with water. While melting and kneading the metal slurry (III) with the thermoplastic resin (II), the water and the thermoplastic resin are removed by removing water contained in the metal slurry (III) as liquid and / or gaseous water. The oxygen-absorbing resin composition according to claim 1, which is produced by a method comprising a step of substituting (II).   The oxygen-absorbing resin composition according to claim 2, wherein a twin-screw extruder having a dehydration slit and / or a vent stuffer is used in the step of replacing the water and the thermoplastic resin (II).   The oxygen-absorbing resin composition according to any one of claims 1 to 3, comprising a dehydrating agent (IV).   The oxygen-absorbing resin composition according to any one of claims 1 to 4, wherein the dehydrating agent (IV) is at least one selected from the group consisting of calcium oxide, calcium chloride, magnesium chloride, and zeolite. .   An oxygen-absorbing film or an oxygen-absorbing sheet comprising the oxygen-absorbing resin composition according to claim 1 and having a film shape or a sheet shape.   Storage of an article for storing an object to be stored using the oxygen-absorbing resin composition according to any one of claims 1 to 5, or the oxygen-absorbing film or the oxygen-absorbing sheet according to claim 6. Method.