JP4248986B2 - Oxygen-absorbing laminate, package using the same, and content filling method using the same - Google Patents

Description

  The present invention relates to an oxygen-absorbing laminate, a package using the laminate, and a method for filling contents using the package.

In the field of packaging business for packaging various contents, the keywords of “package” or “packaging” can include the following contents.
(1) “Display effects” such as giving consumers purchase awareness and presenting dangers.
(2) “Content resistance” so that the package itself is not affected by the filled content itself.
(3) “Protection of contents” against external stimuli.

  These keywords are further subdivided and expanded to fine required quality. Among these, the protection of contents from oxygen and moisture is particularly attracting attention in terms of “protection of contents”. In recent years, in particular, in the fields of food, industrial products, medical / pharmaceutical fields, etc., the protection of contents against oxygen and moisture has been regarded as important. As the background, there are oxygen content decomposition and alteration due to oxidation, and moisture content alteration due to moisture absorption and hydrolysis.

  Various methods have been studied in order to prevent the contents from being altered by oxygen or moisture. One of them is to design a package using a material having an oxygen barrier property or a moisture barrier property. The following are examples of barrier substrates having oxygen barrier properties: laminates using thermoplastic resins with excellent oxygen barrier properties such as ethylene-vinyl alcohol copolymers, aluminum vapor deposition layers, silica vapor deposition layers, alumina The laminated body using the vapor deposition film obtained by providing vapor deposition layers, such as a vapor deposition layer, in a polyester base material etc. are mentioned.

  The packaging body using these barrier substrates is spreading to various uses because of its high oxygen barrier property. However, although these barrier substrates are said to have a high barrier property, they pass a very small amount of oxygen. In addition, when these packages are used to fill the contents, headspace gas is almost always present. Recently, attempts have been made to remove oxygen in the headspace by performing inert gas replacement, since oxygen remaining in the headspace also deteriorates the contents, but a small amount of oxygen still remains. The situation remains.

In this way, oxygen-absorbing resins have been developed to remove a small amount of oxygen passing through the barrier base material or oxygen in the headspace gas inside the package. Among these, the most typical types include the following.
(1) A type using oxidation of a thermoplastic resin with a transition metal (see Patent Document 1).
(2) A type using an oxidative decomposition or oxygen addition reaction of a thermoplastic resin having a carbon-carbon double bond (see Patent Document 2).
(3) An oxygen coordination bond type using a transition metal complex (see Patent Document 3).
(4) Hydrogen peroxide (conversion to other gas) using reduction / oxidation reaction of reducible compound (see Patent Document 4).
(5) A type in which reduced iron is blended with a thermoplastic resin (see Patent Document 5).

First, the oxygen coordination bond type using the transition metal complex of (3) has a low ability to coordinate one molecule of oxygen to one molecule of transition metal in the complex, and functions as an oxygen indicator. It was difficult to develop as an oxygen absorber.
The hydrogenation using the reduction / oxidation reaction of the reducible compound (4) has a problem in hygiene / safety because hydrogen peroxide is generated after oxygen absorption. Another problem is that the thermoplastic resin itself undergoes discoloration (also functions as a pigment) by using this reaction.
Types (1), (2), etc. that utilize the oxidation of thermoplastic resins have problems such as degradation of film properties and odor generation due to side reactions of radical chain reaction accompanying oxygen absorption, such as decomposition and crosslinking by oxidation reaction It is mentioned as a point.

  From the above contents, the type in which reduced iron (5) is blended with a thermoplastic resin is currently mainstream. Originally, this technology is the concept of oxygen scavenger, and the amount of oxygen consumed when reduced iron reacts with iron oxide is extremely large, and it is very effective in terms of oxygen absorption capacity when blended with a thermoplastic resin. The resin composition is developed. However, the problem of this type is that sulfur-containing foods such as eggs and livestock meat generate hydrogen sulfide by an oxidation-reduction reaction and give off a strange odor. Furthermore, it has been confirmed that acidic contents such as vinegar also have an effect of corroding reduced iron in the resin composition.

In addition, the specific gravity of the reaction from reduced iron to iron oxide greatly changes because the crystal structure changes. A change in the specific gravity of the compound contained in the resin composition may affect the physical properties of the resin composition (such as a curl problem in the case of a film). Moreover, since iron or iron oxide is a conductive material, it itself does not have microwave suitability (spark problem). It is possible to improve the influence of sparks by blending in thermoplastic resin, but due to poor dispersion of inorganic compounds and the change in specific gravity associated with the reaction described above, dispersed fine particles come into contact with each other during microwaves. Risk of sparking.
In addition, the content that requires the most improvement is that the reduced iron exhibits oxygen absorption capacity triggered by moisture, so the humidity inside the package is high (the content has a high water activity value or liquid Is required).

Thus, the appearance of oxygen-absorbing resins is an area that is expected in terms of the effect of preserving the contents of future packages, but considering the development of packaging, there are still many improvements to be made. Yes.
In addition, titanium oxide which has an oxygen defect is known as oxygen absorbers other than reduced iron (patent document 6). However, this oxygen absorbent is intended to be used in a sealed container and, of course, has not become a material that can be processed into a package.
Japanese Patent No. 2991437 Japanese Patent No. 3064420 (5th page) Japanese Patent Publication No. 7-82001 (Figs. 1-3) Japanese Patent No. 2922306 (FIGS. 1 to 3) Japanese Patent No. 3019153 Japanese Patent No. 3288265

  Therefore, the object of the present invention is not only to absorb oxygen but also to react with the contents, to have microwave suitability, and to absorb oxygen without depending on environmental humidity and water activity of the contents. An object of the present invention is to provide a packaging body that can be expressed, a filling method that efficiently expresses the oxygen absorption capacity of the packaging body, and an oxygen-absorbing laminate that is suitably used as a material for such a packaging material.

That is, the oxygen-absorbing laminate of the present invention has a resin composition (A) layer in which an inorganic oxide subjected to a reduction treatment and an inorganic compound capable of retaining moisture are dispersed in a thermoplastic resin. The total amount of the inorganic oxide subjected to the reduction treatment and the inorganic compound capable of retaining moisture is 1 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin .

Here, the inorganic oxide subjected to the reduction treatment is preferably an inorganic oxide having oxygen defects.
The inorganic oxide having oxygen defects is preferably at least one selected from the group consisting of titanium dioxide having oxygen defects, zinc oxide, and cerium oxide.
In addition, the oxygen defect ratio of the inorganic oxide having oxygen defects is preferably 0.01 to 25%.
The inorganic compound capable of retaining moisture is preferably at least one selected from the group consisting of magnesium sulfate, calcined meteorite, clay mineral, allophane, zeolite, activated carbon, activated alumina, and silica gel.

  The thermoplastic resin may be low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, olefin copolymer, poly α-olefin, ethylene-α, β unsaturated carboxylic acid copolymer, ethylene-α, β-unsaturated carboxylic acid ester copolymer, ionic cross-linked product of ethylene-α, β-unsaturated carboxylic acid copolymer, ethylene-vinyl acetate copolymer, partial / completely saponified product of ethylene-vinyl acetate copolymer, poly It is desirable to be at least one selected from the group consisting of vinyl acetate, polyvinyl acetate partial / completely saponified product, aromatic polyester, aliphatic polyester, aromatic polyamide, and aliphatic polyamide.

The oxygen-absorbing laminate of the present invention has a barrier layer having an oxygen permeability of 50 cm ³ × 25 μm (thickness) / m ² (area) / 24 h / (1.01325 × 10 ⁵ Pa) (pressure) or less. It is desirable to have
The barrier layer is preferably at least one selected from the group consisting of a thermoplastic resin layer, a metal foil layer, and a vapor deposition layer.
The package of the present invention is characterized by using the oxygen-absorbing laminate of the present invention.

In addition, the filling method of the present invention comprises placing the package of the present invention under high humidity, a moisture absorption step of absorbing an inorganic compound capable of retaining moisture, and contents in the package under a humidity lower than the moisture absorption step. And a filling step of filling.
In addition, the filling method of the present invention comprises placing the package of the present invention under high humidity, a moisture absorption step of absorbing an inorganic compound capable of retaining moisture, and contents in the package under a humidity lower than the moisture absorption step. It has the filling process filled and the microwave irradiation process which irradiates a package to which the contents were filled with a microwave.
In addition, the resin composition having oxygen-absorbing ability of the present invention contains a thermoplastic resin, an inorganic oxide subjected to a reduction treatment, and an inorganic compound capable of retaining moisture, and an inorganic oxide subjected to a reduction treatment. And the total amount of the inorganic compound capable of retaining moisture is 1 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

The oxygen-absorbing laminate of the present invention has a resin composition (A) layer containing a thermoplastic resin, an inorganic oxide subjected to reduction treatment, and an inorganic compound capable of retaining moisture, and is subjected to reduction treatment. Since the total amount of the applied inorganic oxide and the inorganic compound capable of retaining moisture is 1 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin, not only has oxygen absorption capacity but also the contents It is suitable as a packaging material that does not cause a reaction, has microwave suitability, and can express oxygen absorption ability without depending on the environmental humidity and the water activity of the contents.
The oxygen-absorbing laminate of the present invention is adjacent to the resin composition (B) layer containing a thermoplastic resin and a reduced inorganic oxide, and the resin composition (B) layer. An inorganic oxide having a resin composition (C) layer containing a thermoplastic resin and an inorganic compound capable of retaining moisture, and having undergone a reduction treatment, is 100 mass of the thermoplastic resin of the resin composition (B) layer. 1 to 100 parts by mass with respect to parts, and the inorganic compound capable of retaining moisture is 1 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin of the resin composition (C) layer. It is suitable as a packaging material that does not react with the contents, has microwave suitability, and can express oxygen absorption capacity without depending on the environmental humidity and the water activity of the contents. Become.

Here, the inorganic oxide subjected to the reduction treatment may be at least one selected from the group consisting of an inorganic compound having oxygen defects, specifically, titanium dioxide having oxygen defects, zinc oxide, and cerium oxide. In this case, an inorganic oxide having oxygen defects can be easily obtained.
Moreover, if the ratio of the oxygen defect of the inorganic oxide which has the said oxygen defect is 0.01 to 25%, there will be little change of the physical property by oxygen absorption of the package body obtained.

Further, the oxygen-absorbing laminate of the present invention has an oxygen permeability of 50 cm ³ × 25 μm (thickness) / m ² (area) / 24 h / (1.01325 × 10 ⁵ Pa) (pressure) or less. If it has, it will become possible to absorb oxygen gas over a long period of time, since there is little fall of the oxygen absorption ability by the oxygen gas permeate | transmitted from the exterior of a package body.
Further, since the package of the present invention uses the laminate of the present invention, it not only has an oxygen absorption capacity, but also does not react with the contents, has microwave suitability, environmental humidity and The oxygen absorbing ability can be expressed without depending on the water activity of the contents.

In addition, the filling method of the present invention includes a moisture absorption step in which the package of the present invention is placed under high humidity to absorb moisture in an inorganic compound capable of retaining moisture, and the contents are placed in the package under a humidity lower than the moisture absorption step. Since it has the filling process filled, the oxygen absorption ability of a package can be expressed efficiently.
In addition, the filling method of the present invention includes a moisture absorption step in which the package of the present invention is placed under high humidity to absorb moisture in an inorganic compound capable of retaining moisture, and the contents are placed in the package under a humidity lower than the moisture absorption step. Since it has the filling process filled and the microwave irradiation process which irradiates a package to which the contents were filled, the oxygen absorption capacity of a package can be expressed efficiently.
Further, the resin composition having oxygen absorbing ability of the present invention is a resin composition in which an inorganic oxide subjected to a reduction treatment and an inorganic compound capable of retaining moisture are dispersed in a thermoplastic resin. Since the total amount of the treated inorganic oxide and the inorganic compound capable of retaining moisture is 1 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin, not only has oxygen absorption capacity but also the contents It is suitable as a material for a package that has microwave suitability and does not depend on environmental humidity or the water activity of the contents and can express oxygen absorption ability.

Hereinafter, the present invention will be described in detail.
The oxygen-absorbing laminate of the present invention has a structure having a resin composition (A) layer containing (I) a thermoplastic resin, a reduction-treated inorganic oxide, and an inorganic compound capable of retaining moisture. A basic structure (hereinafter also referred to as oxygen-absorbing laminate (I)); or (II) a resin composition (B) layer containing a thermoplastic resin and a reduced inorganic oxide; And a structure having a resin composition (C) layer containing a thermoplastic resin and an inorganic compound capable of retaining moisture adjacent to the resin composition (B) layer (hereinafter referred to as oxygen absorption) (Also referred to as a conductive laminate (II)).

<Reduced inorganic oxide>
The inorganic oxide subjected to the reduction treatment in the present invention has oxygen defects in which some of the oxygen atoms in the inorganic oxide are removed and lattice defects are formed by performing the reduction treatment on the inorganic oxide. An inorganic oxide is mentioned.
Examples of the inorganic oxide include photoconductive inorganic compounds such as titanium dioxide, zinc oxide, and cerium oxide. These can be used alone or in combination of two or more.

  The reduction treatment of the inorganic oxide is carried out by subjecting the photoconductive inorganic compound to a reduction catalyst as needed under an oxygen-free condition and in an atmosphere of a mixed gas of an inert gas such as argon, neon, helium, and nitrogen and hydrogen gas. In the presence, heating or irradiation with light such as UV is performed. In particular, by using heat treatment and light irradiation in combination, an inorganic oxide having an oxygen defect with a large proportion of oxygen defects can be obtained in a short time. In that sense, in the present invention, it is preferable to use a compound having high photosensitivity, that is, a photoconductive inorganic compound.

  Examples of the photoconductive inorganic compound include titanium dioxide, zinc oxide, and cerium oxide described above. The crystal form of titanium dioxide includes anatase type, rutile type, brookite type, etc., the crystal form of zinc oxide includes wurtzite type, and the crystal form of cerium oxide includes lanthanum oxide type, meteorite Examples include molds. Of these, anatase-type titanium dioxide is particularly suitable as the photoconductive inorganic compound in the present invention including factors such as production.

  The proportion of oxygen defects in the inorganic oxide having oxygen defects is preferably in the range of 0.01 to 25%. If the ratio of oxygen defects is less than 0.01%, the oxygen absorption capacity is poor. When the proportion of oxygen defects exceeds 25%, the inorganic oxide forms another crystal structure, or the crystallinity cannot be maintained and becomes amorphous, and the crystal structure collapses. The reactivity with oxygen is reduced, and the oxidation reaction is difficult to occur. Wide-angle X-ray diffraction is the most effective method for confirming the change in crystal structure.

<Inorganic compounds capable of retaining moisture>
The inorganic compound capable of retaining moisture in the present invention is an inorganic compound capable of retaining moisture in the form of coordination water, lattice water, zeolite water, adsorbed water, and the like. Is a material that can absorb and release moisture in order to maintain the equilibrium vapor pressure relationship with the moisture it holds.
Examples of inorganic compounds capable of retaining moisture include sulfates such as magnesium sulfate and calcined meteorite; clay minerals, allophane, zeolite, activated carbon, activated alumina, silica gel, and the like.

<Thermoplastic resin>
Thermoplastic resins include low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, olefin copolymers, poly α-olefins, ethylene-α, β unsaturated carboxylic acid copolymers, ethylene-α, β unsaturated. Saturated carboxylic acid ester copolymer, ionic cross-linked product of ethylene-α, β-unsaturated carboxylic acid copolymer, ethylene-vinyl acetate copolymer, partial / completely saponified product of ethylene-vinyl acetate copolymer, polyvinyl acetate And partially / saponified polyvinyl acetate, aromatic polyester, aliphatic polyester, aromatic polyamide, and aliphatic polyamide. These can be used alone or in combination of two or more. What is necessary is just to select an appropriate material from these according to the package finally calculated | required.

Examples of polypropylene include homopolypropylene, random polypropylene, and block polypropylene.
The olefin copolymer is two or more selected from the group consisting of ethylene, propylene, and C4 or higher α-olefins (1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc.). These are copolymers of olefins, including ethylene-cyclic olefin copolymers.
Examples of the poly α-olefin include polybutene-1, poly-4-methylpentene-1.
Examples of the ethylene-α, β unsaturated carboxylic acid copolymer include an ethylene- (meth) acrylic acid copolymer, and examples of the ethylene-α, β unsaturated carboxylic acid ester copolymer include ethylene- (meth). An acrylic ester copolymer is mentioned, As an ionic cross-linked product of an ethylene-α, β unsaturated carboxylic acid copolymer, various ionic cross-linked products of ethylene- (meth) acrylic acid are mentioned.

<Resin composition>
The resin composition (A) layer in the oxygen-absorbing laminate (I) is a total of 1 to 100 inorganic oxides that have been subjected to reduction treatment and inorganic compounds capable of retaining moisture with respect to 100 parts by mass of the thermoplastic resin. It is a layer which consists of a resin composition (A) which mix | blended the mass part. When the total amount of the inorganic oxide subjected to the reduction treatment and the inorganic compound capable of retaining moisture is less than 1 part by mass with respect to 100 parts by mass of the thermoplastic resin, the oxygen absorption capacity is poor. When the total amount of the inorganic oxide subjected to the reduction treatment and the inorganic compound capable of retaining moisture exceeds 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin, the performance of the package (mechanical strength, heat seal strength) Etc.).

  The resin composition (B) layer in the oxygen-absorbing laminate (II) is a resin composition (B containing 1 to 100 parts by mass of an inorganic oxide subjected to reduction treatment with respect to 100 parts by mass of the thermoplastic resin. ). When the blending amount of the inorganic oxide subjected to the reduction treatment is less than 1 part by mass with respect to 100 parts by mass of the thermoplastic resin, the oxygen absorbing ability is inferior. When the blending amount of the inorganic oxide subjected to the reduction treatment exceeds 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin, the performance (such as mechanical strength and heat seal strength) of the package is affected.

  The resin composition (C) layer in the oxygen-absorbing laminate (II) is a resin composition (C) in which 1 to 100 parts by mass of an inorganic compound capable of retaining moisture is blended with 100 parts by mass of the thermoplastic resin. It is the layer which consists of. When the blending amount of the inorganic compound capable of holding moisture is less than 1 part by mass with respect to 100 parts by mass of the thermoplastic resin, the moisture necessary for the expression of oxygen absorbing ability is insufficient. When the blending amount of the inorganic compound capable of retaining moisture exceeds 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin, the performance of the package (mechanical strength, heat seal strength, etc.) is affected.

  In order to improve the dispersibility of the inorganic oxide that has been subjected to the reduction treatment and the inorganic compound that can retain moisture, the resin compositions in the present invention include, for example, a polyolefin wax and a surfactant. You may mix | blend a dispersing agent suitably. In addition, various additives such as phenol-based, phosphorus-based or lactone-based antioxidants, fillers, flame retardants, light stabilizers, ultraviolet absorbers, slip agents, anti-blocking agents may be blended. .

  Each resin composition in the present invention is obtained by dry blending various materials of a predetermined blending amount set according to the molding method of the final product and the required oxygen absorption capacity using a ribbon mixer, a tumbler mixer, a Henschel mixer, Alternatively, what is blended in a predetermined amount using each feeder mounted in the kneader in advance is used as a base thermoplasticity by using an extruder such as a single-screw extruder or twin-screw extruder, or a kneader such as a Banbury mixer. It can be obtained by kneading at a melting point of the resin to 260 ° C. or less, preferably 240 ° C. or less, more preferably 220 ° C. or less.

<Oxygen-absorbing laminate>
The resin composition in the present invention has an oxygen-absorbing property having a single film film or a resin composition layer of a resin composition using various molding methods such as extrusion lamination molding, extrusion cast molding, inflation molding, injection molding, and direct blow molding. It can be a laminate.
In addition, the obtained film (such as an inflation film) can be formed into an oxygen-absorbing laminate by dry lamination, wet lamination, non-solvent lamination, or the like in a later step.
In addition, the preform obtained by injection molding can be formed into a multilayer stretch blow bottle by stretch blow molding. The molding method is not limited to these molding methods.

In consideration of development on the package, it is preferable to remove oxygen from the outside of the package as much as possible. Therefore, as an oxygen-absorbing laminate, a barrier layer having an oxygen permeability of 50 cm ³ × 25 μm (thickness) / m ² (area) / 24 h / (1.01325 × 10 ⁵ Pa) (pressure) or less is packaged. It is preferable to provide the barrier layer so as to be an outer layer rather than the resin composition (A) layer and the resin composition (B) layer having oxygen absorbing ability when formed into a body. In addition, when a barrier layer is provided on the oxygen-absorbing laminate (II), moisture affects the inorganic oxide that has been subjected to reduction treatment when moisture is absorbed by an inorganic compound that can retain moisture in the filling method described later. In order to avoid this, it is preferable that the resin composition (C) layer is provided as an inner layer rather than the resin composition (B) layer when the package is formed.
Examples of the barrier layer include a thermoplastic resin layer, a metal foil layer, and a vapor deposition layer. These can be used alone or in combination of two or more.

Materials for the thermoplastic resin layer include polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyamide resins such as polyamide 6, polyamide 6-polyamide 66 copolymer, aromatic polyamide (such as MXD6); polyacrylonitrile, polyvinyl alcohol And thermoplastic resins having barrier properties such as ethylene-vinyl alcohol copolymer and polyvinylidene chloride.
Examples of the material for the metal foil layer include aluminum foil.

As a vapor deposition layer, the vapor deposition thermoplastic resin layer which provided the aluminum vapor deposition layer, the silica vapor deposition layer, and the alumina vapor deposition layer in the thermoplastic resin layer is mentioned. Vapor deposition is performed by PVD vapor deposition such as aluminum, silica, and alumina, or CVD vapor deposition using organosilane such as hexamethylenedisiloxane, acetylene gas, and other carbon gas sources.
Furthermore, in order to improve the gas barrier property in these vapor deposition layers, especially the vapor deposition layer by PVD vapor deposition, you may provide the overcoat layer of a polyvinyl alcohol / silane compound system. Moreover, you may provide the various primer layers for improving the adhesiveness of a vapor deposition layer and a thermoplastic resin layer.

  By using these barrier layers, the oxygen gas slightly permeated through these barrier layers is completely absorbed by the resin composition (A) layer and the resin composition (B) layer having oxygen absorption ability. In addition, since the decrease in the oxygen absorption capacity due to the permeated oxygen gas is small, the oxygen gas in the head space of the package can be absorbed.

  Various methods can be used for laminating these barrier layers with a laminate having each resin composition layer. The most typical example is a method of laminating a barrier layer and a laminate having a resin composition layer by a dry lamination method using a urethane-based adhesive; using a urethane-based adhesive for the barrier layer , A method of laminating a laminate having a resin composition layer formed in-line by an extrusion lamination method or a kneelam method; a resin composition on a urethane-based adhesive provided on a barrier layer in-line by a sand lamination method A method of sandwiching a laminate having a physical layer with a polyolefin resin formed by extrusion lamination; and further, by laminating a cast or blown film of a polyolefin resin on the barrier layer by a dry lamination method in advance. The resin composition layer is formed by the method described above using the layer. The method of laminating a laminate that can be cited.

In the oxygen-absorbing laminate of the present invention described above, oxygen absorption can be performed by oxidizing the inorganic oxide subjected to the reduction treatment in the atmosphere.
In addition, since the inorganic compound capable of retaining moisture accumulates moisture to develop the oxygen-absorbing ability of the moisture-triggered and reduced inorganic oxide, Oxygen absorption can be started by releasing.

The oxygen-absorbing laminate of the present invention is suitable as a packaging material that does not react with the contents, has microwave suitability, and has little change in physical properties due to oxygen absorption.
That is, the oxidation reaction from reduced iron to iron oxide in a conventional resin composition having oxygen absorbing ability significantly changes the crystal structure and is accompanied by a change in specific gravity. The specific gravity of reduced iron is greater than the specific gravity of iron oxide, and the reaction from reduced iron to iron oxide causes an increase in weight due to the oxidation reaction. This content suggests the volume expansion of the resin composition having oxygen absorbing ability, and this reaction in the resin composition is caused by the physical properties of the resin composition, the physical properties of the laminate or the package ( There is a risk of sparking during microwaves from curling, breakage of the resin layer, etc.) or contact of the iron oxide phase accompanying volume expansion. In addition, sulfur-containing foods generate hydrogen sulfide by an oxidation-reduction reaction and give off a strange odor. In this sense, the oxygen-absorbing laminate according to the present invention is such that the inorganic oxide having Schottky defects is not accompanied by a large change in crystal structure before and after oxygen absorption, and accordingly, the change in specific gravity is small. When showing conductivity, it is possible to avoid concerns that have been confirmed at the time of reduced iron because of the necessity of high energy rays such as UV and the absence of oxidation-reduction reaction with sulfur-containing foods. .

<Packaging body>
The example at the time of expand | deploying to a package using these laminated bodies is shown below. In particular, the oxygen-absorbing laminate (II) will be described.
Here, A: polyolefin resin, B: acid anhydride graft modified polyolefin resin, C: ethylene-vinyl alcohol copolymer, D: alumina vapor deposition polyester film, E: aluminum foil, F: ethylene- (meth) acrylic acid co Polymer, G: polyvinyl alcohol-based overcoat layer, H: urethane-based adhesive, I: polyester film.

(Structure example-1): A / B / C / B / resin composition (B) / resin composition (C) / A
Molding method: extrusion molding, injection molding, blow molding, etc.
Application: Sheets, bottles, cups, trays, etc.
(Configuration Example-2): D / G / H / A / resin composition (B) / resin composition (C) / A
Molding method: extrusion lamination, dry lamination, etc.
Application: Soft packaging, cover material.
(Structure Example-3): I / H / E / F / resin composition (B) / resin composition (C) / A
Molding method: extrusion lamination, etc.
Application: Inner cap etc.
(Structure Example-4): Paper / A / D / G / H / A / Resin Composition (B) / Resin Composition (C) / A
Molding method: extrusion lamination, etc.
Application: Composite paper container.

  As described above, the laminates obtained in various configurations can be directly developed into packaging bodies for various uses. Moreover, there is no problem even if it uses for the apparatus which emits microwaves, such as a microwave oven, about the structure which does not use aluminum foil. Furthermore, it can also be applied to sulfur-containing foods that were difficult to develop using iron. These examples are not limited to the contents described above, and can be developed into various packaging forms. Moreover, it becomes possible to form the package body which absorbs oxygen by combining these packaging forms.

<Filling method>
There are roughly two methods for starting oxygen absorption in the package of the present invention. One is to store the package in a high-humidity environment (specifically, a humidity of 65% or more) before the contents are filled, and previously absorb the inorganic compound capable of retaining moisture. Since the inorganic compound that can retain moisture before the moisture reaches the inorganic oxide subjected to the reduction treatment retains the moisture, the moisture does not affect the inorganic oxide subjected to the reduction treatment at this stage. And when the package is filled with contents with low water activity in a relatively low humidity environment, the moisture can be retained in order to balance the equilibrium vapor pressure between the inorganic compound capable of retaining moisture and the internal environment of the package. Water is released from the inorganic compound, and the inorganic oxide that has been subjected to the reduction treatment using the water as a trigger can start oxygen absorption.

  The second method uses a microwave. The package of the present invention has microwave suitability. Microwaves promote the movement of water molecules and vaporize as water vapor. In the case of a configuration having an aluminum foil, it is difficult, but for other configurations, there is an inorganic compound that can retain moisture by applying microwaves from the outside of the package or from the inside before filling the contents. The retained water can be vaporized, and the inorganic oxide subjected to the reduction treatment using the water as a trigger can start oxygen absorption.

  The above-mentioned content is about storing in a high-humidity environment before filling the package with the contents, but in the case of a material such as zeolite whose dehydration temperature is around 200 ° C. In particular, it is possible to obtain a resin composition in which moisture has been absorbed in advance by kneading a preabsorbed zeolite and a thermoplastic resin at a temperature lower than the dehydration temperature.

Examples of the present invention are shown below. The present invention is not limited to these.
In this example, the following materials were used.
[Resin composition]
<Thermoplastic resin>
A-1: An ethylene-hexene-1 copolymer (density 0.920 g / cm ³ , MI = 4.0, “Umerit (trade name)” manufactured by Ube Industries, Ltd.).

<Inorganic oxide>
B-1: Anatase type titanium dioxide (lattice defect rate (oxygen defect rate) 7.5%, obtained by hydrothermal reduction of B-2 titanium dioxide, low-order oxidation maintaining anatase type crystal structure Titanium, TiO _1.85 ).
B-2: Anatase type titanium dioxide (powdered titanium dioxide having an anatase type crystal structure having a lattice defect rate (rate of oxygen defects) of 0%, a specific surface area of 280 m ² / g and a purity of TiO ₂ of 93%. Most of the impurities are moisture).

<Inorganic compounds>
C-1: Shomeikan (sulfate compound, manufactured by Kanto Chemical Co., Inc.).
C-2: Activated alumina (manufactured by Kanto Chemical Co., Inc.).
C-3: Calcium oxide (manufactured by Kanto Chemical Co., Inc.).

[Laminate]
<Thermoplastic resin>
D-1: ethylene-hexene-1 copolymer (density 0.920 g / cm ³ , MI = 4.0, “Umerit (trade name)” manufactured by Ube Industries, Ltd.).

<Barrier substrate>
E-1: Biaxially stretched polyester film (12 μm) / polyurethane adhesive (4 μm) / aluminum foil (7 μm, manufactured by Toyo Aluminum Co., Ltd.).
E-2: Biaxially stretched polyester film (12 μm) / alumina deposited layer / overcoat layer (oxygen permeability 0.5 cm ³ × 25 μm (thickness) / m ² (area) / 24 h / (1.01325 × 10 ⁵ Pa), “GL-AE (trade name)” manufactured by Toppan Printing Co., Ltd.).

[Example 1]
To 100 parts by mass of the thermoplastic resin (A-1), 30 parts by mass of an inorganic oxide (B-1), 30 parts by mass of an inorganic compound (C-1), and 0.2 parts by mass of a polyolefin-based dispersant are added. The mixture premixed by dry blending was kneaded with a twin screw extruder (φ = 30, L / D = 49) under the conditions of discharge 9 kg, 180 ° C., 50 rpm to obtain a resin composition having oxygen absorption ability. . The obtained resin composition was air-cooled pelletized, and the inorganic oxide (B-1) (reduction treatment was performed in the thermoplastic resin (A-1) (thermoplastic resin 1) as shown in FIG. A pellet in which inorganic oxide 2) and inorganic compound (C-1) (inorganic compound 3 capable of retaining moisture) were dispersed was obtained.

(Evaluation of oxygen absorption capacity of resin composition)
By storing 3 g of pellets of the resin composition in advance at 25 ° C.-65% relative humidity for 24 hours, the inorganic compound capable of retaining moisture was absorbed. Thereafter, the resin composition was sealed in an aluminum pouch. 75 ml of air was sampled in a constant temperature bath with a humidity of 20% RH, and this air was filled in an aluminum pouch. The oxygen concentration in the aluminum pouch over time was measured with an oxygen concentration meter. The results are shown in FIG.

[Example 2]
Except that the inorganic compound (C-2) was used instead of the inorganic compound (C-1), pellets were prepared in the same manner as in Example 1, and the oxygen absorption capacity was evaluated. The results are shown in FIG.

[Comparative Example 1]
Example 1 was used except that the inorganic compound (C-1) was not used and the amount of the inorganic oxide (B-1) was changed to 16 parts by mass with respect to 100 parts by mass of the thermoplastic resin (A-1). Then, pellets were prepared and the oxygen absorption capacity was evaluated. The results are shown in FIG.

[Comparative Example 2]
Except that the inorganic oxide (B-2) was used instead of the inorganic oxide (B-1), pellets were prepared in the same manner as in Example 1, and the oxygen absorption capacity was evaluated. The results are shown in FIG.

[Comparative Example 3]
Except that the inorganic compound (C-3) was used instead of the inorganic compound (C-1), pellets were prepared in the same manner as in Example 1, and the oxygen absorption capacity was evaluated. The results are shown in FIG.

  From the above contents, it was confirmed that by incorporating an inorganic compound capable of retaining moisture, it was possible to express oxygen absorption ability even in a low humidity environment. On the other hand, about the resin composition which does not mix | blend the inorganic compound which can hold | maintain a water | moisture content, it was confirmed that it is inferior to oxygen absorption ability (comparative example 1). It was also confirmed that an inorganic oxide having no lattice defects (oxygen defects) does not exhibit oxygen absorption behavior (Comparative Example 2). In addition, even for inorganic compounds that can retain moisture, materials that take in moisture into the structure by chemical reaction, such as calcium oxide, have a very low oxygen absorption capacity because it is difficult to release moisture. It was also confirmed (Comparative Example 3).

[Example 3]
To 100 parts by mass of the thermoplastic resin (A-1), 33 parts by mass of the inorganic oxide (B-1) and 0.2 parts by mass of the polyolefin-based dispersant were added, and a mixture obtained by premixing these by dry blending was mixed with 2 parts. A resin composition (B) was obtained by kneading with a shaft extruder (φ = 30, L / D = 49) under the conditions of discharge 9 kg, 180 ° C., 50 rpm. The obtained resin composition (B) was air-cooled pelletized.
Further, to 100 parts by mass of the thermoplastic resin (A-1), 33 parts by mass of the inorganic compound (C-1) and 0.2 parts by mass of the polyolefin-based dispersant were added, and a mixture obtained by premixing these by dry blending was added. A resin composition (C) was obtained by kneading with a twin screw extruder (φ = 30, L / D = 49) under the conditions of discharge 9 kg, 180 ° C., 50 rpm. The obtained resin composition was air-cooled pelletized.

Using a three-type three-layer coextrusion laminating machine, the resin composition (B), the resin composition (C), and the thermoplastic resin (D-1) are coextruded to produce a coextruded multilayer film having the following layer structure. did.
(Inside) Resin composition (B) layer (30 μm) / Resin composition (C) layer (30 μm) / Thermoplastic resin (D-1) layer (outside)

A multilayer film in which a cast film (40 μm) of low-density polyethylene (LDPE) was previously laminated on the barrier substrate (E-1) by a dry laminating technique was used. Lamination was performed via molten LDPE (20 μm) at 0 ° C. to obtain an oxygen-absorbing laminate shown in FIG. In the figure, reference numeral 11 is a resin composition (B) layer, reference numeral 12 is a resin composition (C) layer, reference numeral 13 is a thermoplastic resin (D-1) layer, and reference numeral 14 is a barrier substrate (E-1). A reference numeral 15 denotes an adhesive layer, and a reference numeral 16 denotes an LDPE layer. The final layer structure is as follows.
Barrier substrate (E-1) / adhesive / LDPE (40 μm) / LDPE (20 μm) / resin composition (B) layer / resin composition (C) layer / thermoplastic resin (D-1) layer

(Low humidity trigger function)
The oxygen-absorbing laminate was cut into a size of 220 × 220 mm, further folded in two, and then sealed with a heat sealer having a seal width of 10 mm, thereby producing a 220 × 110 mm size pouch with an effective area of 40000 mm ² . After storing this pouch at 25 ° C.-65% relative humidity for 24 hours, 100 ml of nitrogen gas adjusted to 4% oxygen concentration was filled in the pouch together with 150 g of tea leaves having a water activity of 0.3 to 0.4. The transition of the headspace oxygen concentration over time was measured with an oximeter. The headspace oxygen concentration of the pouch is shown in FIG.

[Example 4]
A pouch was produced in the same manner as in Example 3 except that the barrier substrate (E-2) was used instead of the barrier substrate (E-1). After storing this pouch at 25 ° C.-65% relative humidity for 24 hours, 100 ml of nitrogen gas adjusted to 4% oxygen concentration was filled in the pouch together with 150 g of tea leaves having a water activity of 0.3 to 0.4. Thereafter, the pouch was set in a batch-type apparatus capable of generating a microwave, and the microwave was irradiated under the condition that the pouch was not broken. The transition of the headspace oxygen concentration over time was measured with an oximeter. The headspace oxygen concentration of the pouch is shown in FIG.

  From the contents of the above examples, in the package of the present invention, by using the above-described resin composition, an inorganic compound capable of retaining moisture under low humidity is released in order to maintain equilibrium with the vapor pressure in the environment. It was confirmed that the moisture which acted as a trigger of oxygen absorption. Moreover, it was confirmed that the generation of water vapor by applying microwaves worked as a trigger for oxygen absorption.

  The package of the present invention can express oxygen absorbing ability even under low humidity even if it uses a moisture-triggered inorganic oxide that could not express oxygen absorbing ability under low humidity. It is. In addition, the package of the present invention can be expanded to livestock-related contents that have been difficult with iron-based oxygen absorbers and frozen foods that require microwave suitability. The resin composition having oxygen absorbing ability according to the present invention can be further laminated with a paper base material to be developed into a composite paper container. Furthermore, development to a multilayer sheet molded product or a multilayer (stretched) blow container is possible by developing the resin to be used and the molding method.

It is a schematic sectional drawing which shows the resin composition (pellet) which has the oxygen absorption ability obtained in the Example. It is a graph which shows the change of the head space oxygen concentration in an Example. It is a schematic sectional drawing which shows the laminated body obtained in the Example. It is a graph which shows the change of the head space oxygen concentration of the pouch of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermoplastic resin 2 Inorganic oxide which gave reduction process 3 Inorganic compound which can hold | maintain moisture 11 Resin composition (B) layer 12 Resin composition (C) layer 14 Barrier layer

Claims (12)

In the thermoplastic resin , it has a resin composition (A) layer in which an inorganic oxide subjected to reduction treatment and an inorganic compound capable of retaining moisture are dispersed, respectively .
The oxygen-absorbing laminate, wherein the total amount of the inorganic oxide subjected to the reduction treatment and the inorganic compound capable of retaining moisture is 1 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin. The reduction treatment of an inorganic oxide which has been subjected is, oxygen-absorbing laminate according to claim 1, wherein the inorganic oxide having oxygen defects. The oxygen-absorbing laminate according to claim 2, wherein the inorganic oxide having oxygen defects is at least one selected from the group consisting of titanium dioxide having oxygen defects, zinc oxide, and cerium oxide. The oxygen-absorbing laminate according to claim 2 or 3, wherein a ratio of oxygen defects in the inorganic oxide having oxygen defects is 0.01 to 25%. The inorganic compound capable of retaining moisture is at least one selected from the group consisting of magnesium sulfate, calcined meteorite, clay mineral, allophane, zeolite, activated carbon, activated alumina, and silica gel. 4. The oxygen-absorbing laminate according to any one of 4 above. The thermoplastic resin is low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, olefin copolymer, poly α-olefin, ethylene-α, β unsaturated carboxylic acid copolymer, ethylene-α, β unsaturated. Saturated carboxylic acid ester copolymer, ionic cross-linked product of ethylene-α, β-unsaturated carboxylic acid copolymer, ethylene-vinyl acetate copolymer, partial / completely saponified product of ethylene-vinyl acetate copolymer, polyvinyl acetate , partial / complete saponification product of polyvinyl acetate, aromatic polyesters, aliphatic polyesters, 5 or claims 1, characterized in that at least one selected from the group consisting of aromatic polyamides, and aliphatic polyamides The oxygen-absorbing laminate according to one item. It oxygen permeability claims 1 and having a 50 cm ³ × 25 [mu] m (thickness) / m ² (area) / 24h / (1.01325 × 10 5 Pa) ( pressure) or less is a barrier layer 6 The oxygen-absorbing laminate according to any one of the above. The laminate according to claim 7 , wherein the barrier layer is at least one selected from the group consisting of a thermoplastic resin layer, a metal foil layer, and a vapor deposition layer. A package comprising the oxygen-absorbing laminate according to any one of claims 1 to 8 . A hygroscopic process of placing the package according to claim 9 under high humidity to absorb an inorganic compound capable of retaining moisture;
And a filling step of filling the package with the contents under a humidity lower than that of the moisture absorption step. A hygroscopic process of placing the package according to claim 9 under high humidity to absorb an inorganic compound capable of retaining moisture;
A filling step of filling the package with contents under a humidity lower than the moisture absorption step;
And a microwave irradiation step of irradiating the package filled with the contents with microwaves. A resin composition in which an inorganic oxide subjected to a reduction treatment and an inorganic compound capable of retaining moisture are dispersed in a thermoplastic resin ,
The total amount of the inorganic oxide that has been subjected to the reduction treatment and the inorganic compound capable of retaining moisture is 1 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin, and the resin composition having an oxygen absorption capacity object.

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