JP2018034875A - Oxygen-absorbing film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen-absorbing film that does not generate gas.SOLUTION: A oxygen-absorbing film 100a, 100b at least has an oxygen-absorbing layer 20a, 20b. The oxygen-absorbing layer 20a, 20b contains cerium oxide particles 22 having oxygen deficiency, and a thermoplastic resin 24. In the oxygen-absorbing film, the cerium oxide particles 22 have a particle size D50 of 20.0 μm or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an oxygen-absorbing film.

  For packaging materials for foods, drugs, pharmaceuticals, cosmetics, electronic parts, etc., oxygen-absorbing films have been studied so that the quality of the contents does not deteriorate due to oxidation by oxygen in the package. As this oxygen-absorbing film, a film using cerium oxide having oxygen deficiency has been proposed.

  Patent Document 1 includes an oxygen absorbing layer and a resin layer provided on both sides of the oxygen absorbing layer, the oxygen absorbing layer containing a thermoplastic resin and cerium oxide having oxygen deficiency, and the oxygen absorbing layer. An oxygen-absorbing film is disclosed in which the cerium oxide having oxygen vacancies is contained in the range of more than 50% by weight and less than 85% by weight.

Patent Document 2 includes cerium oxide having an oxygen deficiency and a dehumidifying agent, and the cerium oxide having an oxygen defect is represented by CeO _{2 -X} (x is 0.5 or more and less than 1). A film containing a dehumidifying / deoxidizing agent, characterized by having a superlattice structure having a fluorite-like structure, is disclosed. The average particle diameter of the cerium oxide having oxygen defects is preferably 0.01 to 20 μm.

International Publication No. 2012/105082 Japanese Patent No. 5405744

  An oxygen-absorbing film described in Patent Document 1 in which a resin composition obtained by kneading cerium oxide having oxygen deficiency is used as an intermediate layer and skin layers are formed on both surfaces thereof is laminated with a gas barrier layer such as an aluminum foil for packaging. It can be considered that a laminated body is formed, and, for example, the peripheral edge is heat-sealed so that the oxygen-absorbing film of the laminated body is on the inner side to form a bag product.

  However, the present inventors have found a problem that gas is generated from cerium oxide having oxygen deficiency, which may cause peeling of the heat seal part of the bag-made product. As a result of intensive studies by the present inventors, the generation of this gas is caused by the presence of the resin and moisture, and the hydrogen generated by the reduction of water by the cerium oxide having oxygen deficiency and the decomposition of the resin. I found out.

  In addition, the bag-making product using the oxygen-absorbing film can be used for sealing the contents desired to be sealed under reduced pressure, but the inside of the bag-making product expands due to the generation of the hydrogen, and as a result, It is conceivable that the reliability of the sealed state of the contents is impaired.

  Furthermore, it is conceivable to heat-treat such as heat sterilization after sealing the contents in a bag-making product using an oxygen-absorbing film. However, it has also been found that this hydrogen generation occurs remarkably at high temperatures, which causes peeling of the heat seal part and expansion of the interior of the bag-making product during the heat treatment, resulting in adverse effects on the subsequent processes. Can be considered.

  Accordingly, there is a need to provide an oxygen-absorbing film that does not generate hydrogen.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows:
<1> An oxygen-absorbing film having at least an oxygen-absorbing layer,
The oxygen-absorbing film, wherein the oxygen-absorbing layer contains cerium oxide particles having oxygen deficiency and a thermoplastic resin, and the particle diameter D50 of the cerium oxide particles is 20.0 µm or more.
<2> The oxygen-absorbing film according to <1>, wherein a particle diameter D50 of the cerium oxide particles satisfies the following:
D50 ≦ the thickness of the oxygen absorbing layer + the total thickness of the skin layer × 0.3.
<3> The oxygen-absorbing film according to <1> or <2>, wherein the oxygen-absorbing layer further contains a hygroscopic agent.
<4> The oxygen-absorbing film according to <3>, wherein the hygroscopic agent is calcium oxide.
<5> The oxygen-absorbing film according to <3> or <4>, wherein a mass ratio of the hygroscopic agent to the cerium oxide is 1.0 or more.
<6> The oxygen-absorbing film according to any one of <1> to <5>, which has a skin layer present on one side or both sides of the oxygen-absorbing layer.
<7> A laminate for packaging having the oxygen-absorbing film according to the items <1> to <6> and a barrier layer existing on one side of the oxygen-absorbing film.
<8> A package comprising the package and the packaging laminate according to <7>, wherein the content is sealed.
<9> Contents,
The oxygen absorption film as described in any one of said <1>-<6> term, and the packaging body which has the film for packaging which has sealed the said content and the said oxygen absorption film.
<10> The package according to <9>, wherein at least a part of the packaging film is the laminate for packaging according to <7>.
<11> A method for producing a package having the contents and the packaging laminate according to <7> above,
Sealing the contents with the packaging laminate,
A method for manufacturing a package.

  According to the present invention, an oxygen-absorbing film that does not generate hydrogen can be provided.

FIG. 1 is a side sectional view showing the layer structure of the oxygen-absorbing film of the present invention. FIG. 2 is a side sectional view showing the layer structure of the packaging laminate of the present invention. FIG. 3 is a side sectional view showing the layer structure of the package according to the first embodiment of the present invention. FIG. 4 is a side cross-sectional view showing a problem of a package having a conventional cerium oxide-containing oxygen absorbing layer. FIG. 5 is a side cross-sectional view showing the layer structure of the package of the second embodiment of the present invention.

《Oxygen absorbing film》
As shown to Fig.1 (a) and (b), the oxygen absorptive film (100a, 100b) of this invention is an oxygen absorptive film which has an oxygen absorption layer (20a, 20b) at least. This oxygen absorption layer (20a, 20b) contains cerium oxide particles (22) having oxygen vacancies and a thermoplastic resin (24). Moreover, the oxygen-absorbing film of the present invention may have an optional skin layer (12, 14) present on one side or both sides of the oxygen-absorbing layer (20a, 20b).

  In the oxygen-absorbing film of the present invention, the particle diameter D50 of the cerium oxide particles (22) is 20.0 μm or more.

  As a result of intensive studies, the present inventors have found that the generation of gas in the oxygen-absorbing film using cerium oxide particles having oxygen deficiency is due to the presence of moisture and resin, and that this gas is cerium oxide particles. It was found to be hydrogen generated by water reduction or resin decomposition. And when the present inventors examined further earnestly, it discovered that generation | occurrence | production of hydrogen could be suppressed by making an oxygen absorptive film into said structure.

  More specifically, the present inventors have found that generation of hydrogen can be remarkably suppressed when the particle diameter D50 of the cerium oxide particles is 20.0 μm or more. Although not wishing to be bound by theory, this is because the cerium oxide particles have a large particle size, which makes it difficult for water causing hydrogen generation to reach the inside of the cerium oxide particles, and cerium oxide particles It is considered that the surface area of the resin is reduced, and as a result, the reaction between moisture and resin and the cerium oxide particles is suppressed.

  In addition, as shown in FIG. 1B, the present inventors have further found that the generation of hydrogen can be suppressed even when the oxygen absorption layer (20b) further contains a hygroscopic agent (26). It was. Although not wishing to be bound by theory, it is believed that this is due to the fact that the water that causes the generation of hydrogen is absorbed by the hygroscopic agent so that the water does not reach the surface of the cerium oxide particles.

  Below, each component of this invention is demonstrated.

<Oxygen absorbing layer>
The oxygen absorbing layer contains cerium oxide particles having oxygen deficiency and a thermoplastic resin. Moreover, it is preferable that the oxygen absorption layer further contains a hygroscopic agent from the viewpoint of satisfactorily suppressing the generation of hydrogen.

  The content of the cerium oxide particles having oxygen vacancies in the oxygen absorption layer in terms of mass% based on the mass of the entire oxygen absorption layer is less than 85 mass%, 80 mass% or less, or 75 mass% or less. Can be. In particular, the content is preferably 1% by mass or more, 5% by mass or more, 10% by mass or more, or 20% by mass or more, from the viewpoint of ensuring good oxygen absorption capacity, and 70% by mass or less. It is preferable from a viewpoint of ensuring the film formability of a film that they are 65 mass% or less, 57 mass% or less, 50 mass% or less, 45 mass% or less, or 40 mass% or less.

  The thickness of the oxygen absorbing layer can be 10 μm or more, 20 μm or more, or 30 μm or more, and can be 300 μm or less, 200 μm or less, 100 μm or less, 80 μm or less, or 50 μm or less.

  When the oxygen absorbing layer contains a hygroscopic agent, the content of the hygroscopic agent in units of mass% based on the mass of the entire oxygen absorbing layer is 5 mass% or more, 10 mass% or more, 15 mass%. It can be above or 20% by mass, and can be 70% by mass or less, 60% by mass or less, or 50% by mass or less.

  When the oxygen absorbing layer contains a hygroscopic agent, the mass ratio of the hygroscopic agent to cerium oxide may be 0.1 or more, 0.3 or more, 0.5 or more, or 1.0 or more. Or 15.0 or less, 13.0 or less, or 10.0 or less. In particular, the mass ratio is preferably 1.0 or more from the viewpoint of better suppressing the generation of hydrogen.

{Cerium oxide with oxygen deficiency}
The cerium oxide particles contained in the oxygen absorbing layer are cerium oxide particles having oxygen vacancies.

Here, oxygen vacancies in cerium oxide are forcibly extracted from the crystal lattice of cerium oxide as represented by the following formula (1) by reduction treatment in a strong reducing atmosphere. It is brought about by becoming a state (CeO _2-x , 0 <x <2). The reduction treatment can be performed by heat treatment at a high temperature such as 1000 ° C. in a reducing atmosphere such as hydrogen gas.
CeO ₂ + xH ₂ → CeO _2−x + xH ₂ O (1)

And as shown to the following formula | equation (2), the effect as an oxygen absorber is exhibited when the part which oxygen lacked reacts with oxygen.
CeO _2-x + (x / 2) O ₂ → CeO ₂ (2)

  The value of x can be a positive number of 1.0 or less, and is preferably a positive number of 0.7 or less. As shown in the above formula (2), cerium oxide does not require water to be present in the atmosphere in the reaction with oxygen. Therefore, the oxygen-absorbing film of the present invention is particularly effective for contents that dislike moisture.

  The particle diameter D50 of the cerium oxide particles can be 20 μm or more, 22 μm or more, 25 μm or more, or 30 μm or more, and can be 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, or 35 μm or less. The particle diameter D50 is measured by a laser diffraction / scattering method.

Further, the particle diameter D50 of the cerium oxide particles preferably satisfies the following from the viewpoint of eliminating an error between the designed film thickness and the actual thickness after film formation:
D50 ≦ the thickness of the oxygen absorbing layer + the total thickness of the skin layer × 0.3.

{Thermoplastic resin}
As the thermoplastic resin, a thermoplastic resin having oxygen permeability can be used. Examples of such thermoplastic resins include polyolefin resins, polystyrene resins, polyester resins, acrylic resins, polyamide resins, polyurethane resins, polycarbonate resins, polysulfone resins, and derivatives thereof, and mixtures thereof. Can be mentioned.

  In the context of the present invention, a polyolefin resin means a polymer having an olefinic monomer such as ethylene or propylene, and therefore not only a polymer (polyolefin) consisting of only an olefinic monomer, but also an olefinic monomer and (meth) It also means a copolymer composed of other monomers such as acrylic acid, acrylate monomers, vinyl acetate. Further, the polyolefin-based resin may be acid-modified or not acid-modified.

  Examples of polyolefin resins include polyethylene resins and polypropylene resins. Examples of polyethylene resins include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), ethylene-acrylic acid copolymer (EAA), ethylene- Methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-vinyl acetate copolymer (EVA), carboxylic acid-modified polyethylene, ionomer, and These derivatives, as well as mixtures thereof, can be mentioned. Examples of the polypropylene resin include polypropylene (PP) homopolymer, random polypropylene (random PP), block polypropylene (block PP), chlorinated polypropylene, carboxylic acid-modified polypropylene, and derivatives thereof, and mixtures thereof. .

  Examples of the vinyl resin include PVC (polyvinyl chloride).

  Examples of the polyester resin include PET (polyethylene terephthalate) and polybutylene terephthalate.

  Examples of the polyamide-based resin include nylon such as nylon (registered trademark) 6 and nylon MXD6.

  As the thermal characteristics of the thermoplastic resin, for example, when its melt mass flow rate (MFR) is measured in accordance with JIS K7210, 0.5 g / 10 min or more, 1.0 g or more, 3.0 g / 10 min or more, Alternatively, it may be 5.0 g / 10 min or more, and may be 100 g / 10 min or less, 50 g / 10 min or less, 30 g / 10 min or less, 20 g / 10 min or less, 15 g / 10 min or less, or 10 g / 10 min or less.

{Hygroscopic agent}
As the hygroscopic agent, for example, A-type, X-type or LSX-type hydrophilic zeolite, clay minerals such as hydrotalcite, silica gel, alumina, calcium oxide, hygroscopic salts, and the like are used. These hygroscopic agents may be used alone or in combination. However, from the viewpoint of satisfactorily suppressing the generation of hydrogen, it is preferable to use calcium oxide as the hygroscopic agent.

<Skin layer>
The skin layer is an optional layer that is laminated to the oxygen absorbing layer. Due to the presence of the skin layer, detachment of the cerium oxide particles in the oxygen absorption layer can be prevented.

  The skin layer may be made of a thermoplastic resin. As the thermoplastic resin, the thermoplastic resins mentioned for the oxygen absorbing layer can be used. The thermoplastic resin constituting the skin layer may be the same as or different from the thermoplastic resin that the oxygen absorbing layer has. When the skin layer is laminated on both sides of the oxygen absorption layer, the thermoplastic resins constituting the skin layer may be the same or different from each other.

  The thickness of the skin layer can be 3 μm or more, 5 μm or more, 7 μm or more, or 10 μm or more, and can be 100 μm or less, 50 μm or less, 30 μm or less, or 20 μm or less. When the skin layer is laminated on both sides of the oxygen absorption layer, the thickness of each skin layer may be different, particularly when producing an oxygen-absorbing film by a coextrusion method such as a multilayer inflation method, From the viewpoint of easily producing an oxygen-absorbing film, it is preferable that the thickness of each skin layer is equal.

  As the thermal characteristics of the thermoplastic resin constituting the skin layer, for example, when its melt mass flow rate (MFR) is measured in accordance with JIS K7210, it is 0.1 g / 10 min or more, 0.5 g / 10 min or more, It may be 1.0 g or more, 3.0 g / 10 min or more, or 1.5 g / 10 min or more, 30 g / 10 min or less, 20 g / 10 min or less, or 15 g / 10 min or less, 10 g / 10 min or less, 8 g / 10 min or less. Or 5.0 g / 10 min or less.

《Packaging for packaging》
As shown in FIG. 2, the laminated body for packaging (200) of the present invention has at least the oxygen-absorbing film (100) and the barrier layer (30). Moreover, the laminated body for packaging of the present invention may have an optional resin film (40).

  Lamination | stacking with said oxygen absorptive film, a barrier layer, and / or a resin film may be performed by a heat seal, or may be performed via an contact bonding layer. As the adhesive layer, for example, a dry laminate adhesive, a hot melt adhesive, a water-soluble adhesive, an emulsion adhesive, and a thermoplastic resin for extrusion lamination can be used.

<Barrier layer>
As the barrier layer, metal foil such as pure aluminum foil and aluminum alloy foil; inorganic deposition film such as aluminum deposition film, silica deposition film, alumina deposition film, or silica-alumina binary deposition film; or polyvinylidene chloride coating film, Alternatively, an organic coating film such as a polyvinylidene fluoride coating film can be used, but it is preferable to use a metal foil from the viewpoint of better gas barrier properties.

  The thickness of the barrier layer can be 1 μm or more, 3 μm or more, 5 μm or more, or 7 μm or more, and is 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less. Can do.

{Resin film}
As the resin film, a thermoplastic resin excellent in impact resistance, abrasion resistance, etc., for example, a polyolefin resin, a vinyl resin, a polyester resin, a polyamide resin, a fluorine resin, etc. alone, or two or more kinds It can be used in combination with multiple layers. This resin film may be a stretched film or an unstretched film.

  Polyolefin resins, vinyl resins, polyester resins, and polyamide resins include not only the above thermoplastic resins, but also EVOH (ethylene-vinyl alcohol copolymer), PVA (polyvinyl alcohol), PAN (polyacrylonitrile). Resins having gas barrier properties such as the above can also be used.

  Examples of the fluororesin include PCTFE (polychlorotrifluoroethylene) and PTFE (polytetrafluoroethylene).

  The thickness of the resin film can be 3 μm or more, 5 μm or more, 7 μm or more, 10 μm or more, or 12 μm or more, and is 120 μm or less, 100 μm or less, 80 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, Or it can be 20 micrometers or less.

<Packaging body>
As shown in FIG. 3, the packaging body (300) of the first embodiment of the present invention includes the contents (50) and the packaging laminate (200,) that seals the contents (50). 200 ′).

  Moreover, as shown in FIG. 5, the package (310) of the 2nd embodiment of this invention is the content (50), said oxygen absorptive film (100), and the content (50) and oxygen absorption. A packaging film (70, 70 ') that seals the adhesive film (100).

  Here, in this specification, “sealing” means that the contents are enclosed in a state in which air does not enter from the outside to the inside of the package, for example, the contents are in a deaerated state. A deaeration seal in which an object is enclosed may be used.

  As shown in FIG. 4, a conventional packaging body (350), that is, a packaging laminate (250) having conventional cerium oxide-containing oxygen absorption layers (20c, 20c ′) instead of the oxygen absorption layer of the present invention. , 250 '), it is considered that hydrogen (60) is generated inside the package and causes expansion of the package. In contrast, when the package of the present invention as shown in FIGS. 3 and 5 is used, it is considered that hydrogen generation as shown in FIG. 4 does not occur.

  In the packaging body of the first embodiment of the present invention, the packaging laminate of the present invention may contain the contents, for example, the skin layers may be bonded to each other, or other packaging The film may be bonded to face the film. Adhesion may be performed by heat sealing, or may be performed via the adhesive layer mentioned for the packaging laminate.

  Moreover, in the package of the second embodiment of the present invention, separately prepared packaging films may be bonded to each other so as to accommodate the contents and the oxygen-absorbing film of the present invention. Adhesion may be performed by heat sealing, or may be performed via the adhesive layer mentioned for the packaging laminate.

  Examples of the form of the package include bags, tubes, blister containers, and the like, as well as molded containers such as cup containers.

<Contents>
The contents of the package of the present invention may be optional contents, but if the contents are desirable to prevent deterioration of food, drugs, pharmaceuticals, cosmetics, electronic parts, etc. due to oxygen, this The package of the invention is particularly useful.

<Packaging film>
As the packaging film used in the second embodiment of the present invention, an optional film can be used. From the viewpoint of improving the sealing property of the package, the metal foil layer or the resin film and the metal foil layer are used. It is preferable to have a combination of the above or the above laminate for packaging.

  Moreover, in order to provide heat sealability, the packaging film may have an optional sealant layer.

  Examples of the sealant layer include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene (PP), ethylene-methacrylic acid copolymer (EMAA), and ethylene-acrylic acid copolymer. Resins such as (EAA), ionomer resin, and ethylene-vinyl acetate copolymer can be used.

  As the sealant layer, a commercially available easy peel resin or an easy peel sealant film may be used.

<< Method for producing oxygen-absorbing film >>
The oxygen-absorbing film of the present invention can be produced by a method including a production process of a resin composition for an oxygen-absorbing layer and a film-forming process.

  The resin composition for the oxygen absorbing layer can be produced by kneading the cerium oxide having the oxygen deficiency and a thermoplastic resin. Further, a hygroscopic agent may be further kneaded here.

  For the kneading, for example, a batch kneader such as a kneader, a mixing roll or a conical mixer, a continuous kneader such as a twin screw kneader, a single screw extruder, a two roll kneader, a three roll kneader or the like is used. In this case, kneading may be performed at a temperature of 80 ° C. or higher, 100 ° C. or higher, 120 ° C. or higher, or 140 ° C. or higher, and 220 ° C. or lower, 200 ° C. or lower, or 180 ° C. or lower. it can.

  The kneaded resin composition for an oxygen absorbing layer and the thermoplastic resin constituting the optional skin layer are molded into an oxygen absorbing layer and a skin layer, respectively, and laminated to form the oxygen absorbing film of the present invention. Can be obtained. For example, the above-mentioned kneaded resin composition is formed into a single-layer film by extrusion molding such as an inflation method, a T-die method, or a cast method, and the single-layer oxygen-absorbing film of the present invention is obtained. Can do. Similarly, a single-layer skin layer can be formed using a thermoplastic resin for the skin layer and laminated with the oxygen-absorbing layer to obtain the multilayer oxygen-absorbing film of the present invention. Further, the oxygen absorbing layer and the skin layer can be formed and laminated simultaneously by a multilayer extrusion method or a coextrusion method such as a T-die method.

《Method for manufacturing packaging body》
The method of the present invention for producing a package includes the step of sealing the contents with the packaging laminate of the present invention. This method may include a step of producing a packaging laminate before sealing, and may be optionally sterilized after sealing.

  The production process of the packaging laminate of the present invention is performed by a known adhesion method such as a dry laminating method or an extrusion laminating method in which the oxygen absorbing film obtained by the above-described method for producing an oxygen absorbing film and the barrier layer are bonded. , By laminating.

  For example, the sealing process of the package may be performed by folding the packaging laminate of the present invention in half with the oxygen-absorbing film inside, or the two oxygen-absorbing films of the packaging laminate facing each other and heating the periphery. This can be done by sealing. Heat sealing can be performed, for example, by heating at 60 ° C. or higher, 70 ° C. or higher, or 80 ° C. or higher, and by heating at 220 ° C. or lower, 200 ° C. or lower, 180 ° C. or lower, or 150 ° C. or lower. it can. The sterilization treatment can be performed by heating at, for example, 60 ° C. or higher, 70 ° C. or higher, or 80 ° C. or higher, and can be performed by heating at 200 ° C. or lower, 180 ° C. or lower, or 150 ° C. or lower.

  The generation of hydrogen due to cerium oxide occurs remarkably at high temperatures, which causes peeling of the heat seal part and expansion of the inside of the bag making product during heat treatment, resulting in adverse effects on subsequent processes. However, the present inventors use the packaging laminate having the oxygen-absorbing film as described above, so that hydrogen is not generated even in a high temperature state, and as a result, the above problems do not occur. I found it.

  The present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these.

<< Aspect where particle diameter of cerium oxide particles is 20 μm or more >>
<Production of film>
{Example 1-1}
75 parts by mass of cerium oxide CeO _2-x (x = 0.5) having oxygen deficiency and 25 parts by mass of low-density polyethylene were kneaded to prepare a master batch for an oxygen absorbing layer. The particle diameter D50 of cerium oxide measured by a laser diffraction / scattering method was 37.09 μm.

  As the skin layer, linear low density polyethylene was used.

  The above materials are co-extruded by a two-kind / three-layer film inflation molding machine (TUL-600R, Plako Co., Ltd.), resulting in a layer structure of 10 μm skin layer / 30 μm oxygen absorbing layer / 10 μm skin layer (total 50 μm). Thus, a film was formed.

{Examples 1-2 and 1-3 and Comparative Examples 1-1 to 1-4}
Examples 1-2 and 1-3 and Comparative Examples 1-1 and 1-1 were the same as Example 1-1 except that cerium oxide having a particle diameter D50 of the value shown in Table 1 was used. -4 oxygen-absorbing film was produced.

<Evaluation>
{Evaluation of hydrogen generation}
The produced film was put into a polyethylene terephthalate / aluminum foil / polyethylene packaging bag in a nitrogen environment at 10 cm ² , molded into a tetrahedral bag and sealed so as to have a volume of 101 mL. The tetrahedral bag was then heated at 80 ° C. for 2 hours. Furthermore, the hydrogen concentration in the tetrahedral bag was measured with a Kitagawa type gas detector tube 137U hydrogen (Kitsunari Chemical Co., Ltd.). From the measured value of the hydrogen concentration, the amount of hydrogen generated per unit area of the film was calculated.

{Evaluation of thickness accuracy}
The film after film formation was measured with a film thickness meter, and the deviation from the set value was calculated as a ratio.

{Evaluation of oxygen absorption}
Polyethylene terephthalate / aluminum foil / polyethylene packaging bag, the oxygen-absorbing film 25 cm ² was introduced, the volume of the packaging bag (volume air) is sealed by heat sealing to the tetrahedral so that 15 mL, store at room temperature did.

One week later, the oxygen concentration in the bag of the bag containing the oxygen-absorbing film was measured, and the oxygen absorption amount per cm ² of the oxygen-absorbing film was calculated from the difference from the oxygen concentration in the atmosphere. The measurement was performed by inserting a measuring needle of Packmaster RO-103 (Iijima Electronics Co., Ltd.), which is a diaphragm type galvanic cell type oxygen sensor, into the bag.

  The results are shown in Table 1.

  From Table 1, the oxygen-absorbing films of Examples 1-1 to 1-3 in which the particle diameter D50 of the cerium oxide particles is 20.0 μm or more are the same as the oxygen-absorbing films of Comparative Examples 1-1 to 1-4. In comparison, it can be understood that the amount of hydrogen generation was small. Further, in the examples, the oxygen-absorbing films of Examples 1-2 and 1-3, in which the particle diameter D50 is the sum of the thickness of the oxygen absorbing layer + the thickness of the skin layer × 0.3 or less, It can be understood that the deviation between the set value of the thickness and the actually measured value is small as compared with Example 1-1.

<< Aspect where the oxygen absorption layer contains a hygroscopic agent >>
<Production of film>
{Examples 2-1 to 2-7}
70 parts by mass of calcium oxide as a hygroscopic agent and 30 parts by mass of low density polyethylene (Petrocene 202R, Tosoh Corporation) were kneaded to prepare a calcium oxide-containing masterbatch. In addition, 75 parts by mass of cerium oxide CeO _2-x (x = 0.5) having oxygen deficiency and 25 parts by mass of low-density polyethylene (Petrocene 342, Tosoh Corporation) are kneaded to obtain a cerium oxide-containing master batch. Was made. These two master batches are kneaded using a twin screw extruder so as to have the contents of calcium oxide and cerium oxide shown in Table 1, and the obtained kneaded body is manufactured to a thickness of 75 μm with a T-die. A single layer oxygen-absorbing film of Examples 2-1 to 2-7 was obtained. The particle diameter D50 of cerium oxide measured by the laser diffraction / scattering method was 25.02 μm.

{Comparative Examples 2-1 to 2-4}
Comparative Examples 2-1 to 2- in the same manner as in Example 2-1, except that the cerium oxide-containing masterbatch and the low-density polyethylene were kneaded so as to have the cerium oxide content shown in Table 1. 4 single layer oxygen-absorbing films were obtained.

{Examples 3-1 to 3-4}
The above-mentioned calcium oxide-containing masterbatch and cerium oxide-containing masterbatch are used for an oxygen absorbing layer containing the contents of calcium oxide and cerium oxide shown in Table 1, and a linear low density polyethylene ( Using Evolu SP2520, Prime Polymer Co., Ltd.), co-extrusion with a two-layer, three-layer inflation molding machine was carried out to form a layer structure of skin layer 10 μm / oxygen absorbing layer 75 μm / skin layer 10 μm. A three-layer oxygen-absorbing film of Examples 3-1 to 3-4 was obtained.

{Examples 3-5 to 3-7}
The calcium oxide-containing masterbatch and the cerium oxide-containing masterbatch were used for the oxygen-absorbing layer containing calcium oxide and cerium oxide having the contents shown in Table 1, and the thickness of the oxygen-absorbing layer was 90 μm. Except for the above, a three-layer oxygen-absorbing film of Examples 3-5 to 3-7 was obtained in the same manner as Example 3-1.

{Comparative Example 3-1}
Except that the cerium oxide-containing masterbatch and the low-density polyethylene were kneaded so as to have the cerium oxide content shown in Table 1 and used for the oxygen absorbing layer, the same as in Example 3-1, A three-layer oxygen-absorbing film of Comparative Example 3-1 was obtained.

<Evaluation>
{Evaluation of hydrogen generation}
The produced film was put in a polyethylene terephthalate / aluminum foil / polyethylene bag in a nitrogen environment at 10 cm ² , molded into a tetrahedral bag and sealed so as to have a volume of 101 mL. Next, the tetrahedral bag was heated at 80 ° C. (dry bulb temperature) for 2 hours. Furthermore, the hydrogen concentration in the tetrahedral bag was measured with a Kitagawa-type gas detector tube 137U hydrogen (manufactured by Mitsunari Chemical Industry Co., Ltd.). From the measured value of the hydrogen concentration, the amount of hydrogen generated per gram of cerium oxide particles was calculated.

{Evaluation of oxygen absorption}
Polyethylene terephthalate / aluminum foil / polyethylene packaging bag, the oxygen-absorbing film 25 cm ² was introduced, the volume of the packaging bag (volume air) is sealed by heat sealing to the tetrahedral so that 15 mL, store at room temperature did.

One week later, the oxygen concentration in the bag containing the oxygen-absorbing film was measured, the oxygen absorption amount per 1 cm ² of the oxygen-absorbing film was calculated from the difference from the oxygen concentration in the atmosphere, and the calculated value was the oxygen absorption The amount. The measurement was performed by inserting a measuring needle of Packmaster RO-103 (Iijima Electronics Co., Ltd.), which is a diaphragm type galvanic cell type oxygen sensor, into the bag.

  The results are shown in Table 2.

  When comparing the oxygen-absorbing films of Comparative Examples 2-1 to 2-4 and Comparative Example 3-1, when the oxygen-absorbing layer does not contain a hygroscopic agent, the amount of hydrogen generated per gram of cerium oxide particles is: It will be understood that it does not vary greatly depending on the content of the cerium oxide particles and the presence or absence of the skin layer.

  The oxygen-absorbing films of Examples 2-1 to 2-7 in which the oxygen-absorbing layer further contains a hygroscopic agent are the oxygen-absorbing properties of Comparative Examples 2-1 to 2-4 and Comparative Example 3-1. Compared with the film, the amount of hydrogen generation was significantly reduced, and in particular, the oxygen ratio of Examples 2-1 to 2-4 and 2-7 in which the mass ratio of the hygroscopic agent to cerium oxide was 1.0 or more. It can be seen that the absorbent film has a greater reduction in hydrogen generation. Also in the oxygen-absorbing films of Examples 3-1 to 3-4 having skin layers and the oxygen-absorbing films of Examples 3-5 to 3-7 having thickened oxygen-absorbing layers, Similarly, it can be understood that when the mass ratio of the hygroscopic agent to cerium oxide is 1.0 or more, there is a tendency that the amount of hydrogen generation is favorably reduced.

12, 14, 12 ′, 14 ′ Skin layer 20, 20a, 20b, 20a ′, 20b ′ Oxygen absorbing layer 20c, 20c ′ of the present invention 22 Conventional oxygen absorbing layer 22 Cerium oxide particles having oxygen deficiency 24 Thermoplastic resin 26 Hygroscopic agent 30, 30 'Metal foil layer 40, 40' Resin film 50 Contents 60 Hydrogen 70, 70 'Packaging film 100, 100a, 100b Oxygen absorbing film 200, 200' Laminate for packaging 250, 250 of the present invention '' Packaging laminate having conventional oxygen absorbing layer 300, 310 Packaging of the present invention 350 Conventional packaging having cerium oxide-containing oxygen absorbing layer

Claims (11)

An oxygen-absorbing film having at least an oxygen-absorbing layer,
The oxygen-absorbing film, wherein the oxygen-absorbing layer contains cerium oxide particles having oxygen deficiency and a thermoplastic resin, and a particle diameter D50 of the cerium oxide particles is 20.0 µm or more. The oxygen-absorbing film according to claim 1, wherein a particle diameter D50 of the cerium oxide particles satisfies the following:
D50 ≦ the thickness of the oxygen absorbing layer + the total thickness of the skin layer × 0.3.   The oxygen-absorbing film according to claim 1 or 2, wherein the oxygen-absorbing layer further contains a hygroscopic agent.   The oxygen-absorbing film according to claim 3, wherein the hygroscopic agent is calcium oxide.   The oxygen-absorbing film according to claim 3 or 4, wherein a mass ratio of the hygroscopic agent to the cerium oxide is 1.0 or more.   The oxygen-absorbing film according to any one of claims 1 to 5, further comprising a skin layer existing on one side or both sides of the oxygen-absorbing layer.   The laminated body for packaging which has the barrier layer which exists in the oxygen absorbing film as described in any one of Claims 1-6, and the one side of the said oxygen absorbing film. The package which has the laminated body for packaging of Claim 7 which has sealed the content and the said content. Contents,
The package which has the film for packaging which has sealed the oxygen absorptive film as described in any one of Claims 1-6, and the said content and the said oxygen absorptive film.   The packaging body according to claim 9, wherein at least a part of the packaging film is the packaging laminate according to claim 7. A method for producing a package having the contents and the laminate for packaging according to claim 7,
Sealing the contents with the packaging laminate,
A method for manufacturing a package.

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