JP2000343661A - Oxygen absorbable packaging material, packaging bag using the same, and seal lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen absorbable packaging material, especially, a packaging bag and a seal lid showing excellent content preservability and flavor retention even during long-term preservation after retort sterilization. SOLUTION: An oxygen absorbable packaging material is constituted by successively laminating a polyolefin inner surface material, an oxygen absorbing layer comprising a compsn. of polyolefin and a ferrous oxygen absorbent, a polyolefin cushioning layer, an aluminum foil and a stretched film or an inorg. vapor deposition plastic film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen-absorbing packaging material and a packaging container using the same, and more particularly, it has a specific multilayer structure and is excellent in long-term storage after retort sterilization. The present invention relates to an oxygen-absorbing packaging material exhibiting content preservability and flavor retention, and a container using the oxygen-absorbing packaging material, particularly a packaging bag and a seal lid.

[0002]

2. Description of the Related Art Conventionally, metal cans, glass bottles, various plastic containers, and the like have been used as packaging containers. However, plastic containers have been used for various purposes in terms of lightness, impact resistance, and cost. I have.

However, while oxygen permeation through the container wall is zero in metal cans and glass bottles, oxygen permeation through the container wall occurs in a non-negligible order in the case of plastic containers, and the storage of the contents is It is a problem in terms of gender.

In order to prevent this, in a plastic container, the container wall has a multilayer structure, and at least one of the layers is made of an oxygen-permeable resin such as an ethylene-vinyl alcohol copolymer. I have.

[0005] An oxygen absorber has been used for a long time to remove oxygen in a container. An example of applying the oxygen absorber to a container wall is disclosed in Japanese Patent Publication No. 62-1824. According to this method, a layer formed by mixing an oxygen absorbent containing a reducing substance as a main component in a resin having oxygen permeability and a layer having oxygen gas barrier properties are laminated to form a multilayer structure for packaging.

As an oxygen absorbent, iron-based ones have a high oxygen absorption rate and a large absorption capacity and are excellent in cost, but when iron and its compounds are eluted in the contents,
Even if the amount is very small, there is a problem that the flavor retention of the contents is impaired.

[0007] In order to prevent the elution of the iron-based oxygen absorber into the contents, a resin layer containing no oxygen absorber is sandwiched between the inner and outer surfaces of the resin layer containing the iron-based oxygen absorber. Means for preventing the exposure of the system oxygen absorbent is also employed (see, for example, JP-A-10-114371).

[0008]

Oxygen in a sealed container has a significant effect on the storage stability and flavor retention of the contents of the container. Oxygen existing in the headspace or the like in the sealed container from the initial stage of sealing lowers the flavor retention of the contents. This tendency is particularly remarkable in retort-sterilized packaged foods for the purpose of improving the preservability of the contents.For example, it is known that in canned vegetables and vegetables, the pigment is destroyed and the flavor retention is reduced. Have been. To prevent this, it is also known that the presence of a reducing substance, that is, an oxygen absorbent, in the hermetically sealed package is effective.

On the other hand, oxygen that penetrates into the package through the vessel wall also reduces the preservability of the contents. To prevent this, it is necessary to incorporate a material having oxygen permeability into the laminate. is necessary.

As already pointed out, iron-based oxygen absorbers are:
Oxygen absorption capacity is large, it absorbs oxygen existing from the beginning of sealing and also absorbs oxygen that enters the package through the vessel wall.This oxygen absorption capacity is, of course, within a certain storage period after retort sterilization. There is a problem of being limited.

[0011] In addition, the iron-based oxygen absorbent increases in volume with the progress of oxygen absorption, ie, oxidation, and the tendency to be exposed in the package increases with the volume expansion. It is also observed that the tendency of elution to the iron content increases. Iron is an indispensable mineral for humans, but it is also known that iron mixed in contents significantly impairs the flavor of foods. This tendency is particularly remarkable in the case of retort sterilization of a sealed package.

Accordingly, an object of the present invention is to provide an oxygen-absorbing packaging material exhibiting excellent content preservability and flavor retention even after long-term storage after retort sterilization, and a container using the oxygen-absorbing packaging material, particularly To provide a packaging bag and a sealing lid. Another object of the present invention is to provide an oxygen-absorbing packaging material in which deterioration of the flavor due to oxidation in the packaging and flavor reduction due to elution of iron is suppressed even during long-term storage after retort sterilization.

[0013]

According to the present invention, there is provided an oxygen absorbing layer / polyolefin buffer layer comprising a composition of a polyolefin inner surface material / polyolefin and an iron-based oxygen absorbing agent,
An oxygen-absorbing packaging material is provided, in which an aluminum foil / stretched film or an inorganic vapor-deposited plastic film is sequentially laminated. In the packaging material of the present invention, 1. The stretched film is a nylon film, a polyester film, or a laminated film of a nylon film and a polyester film; 2. A stretched nylon film is laminated between the polyolefin buffer layer and the inorganic vapor-deposited plastic film; 3. Titanium dioxide is blended into the polyolefin inner surface material; 4. the polyolefin inner surface material has a thickness of 5 to 50 μm; 2 per 100 parts by weight of polyolefin in the oxygen absorbing layer
5. to 60 parts by weight of an iron-based oxygen absorbent; The iron-based oxygen absorbent comprises a reducing iron powder and an oxidation promoter or a catalyst coated on the surface of the reducing iron powder. In particular, the oxidation promoter or the catalyst is 0.1 to 10% by weight per the reducing iron powder. 6. be present in an amount of 7%; The polyolefin of the oxygen-absorbing layer is a matrix composed of a blend of a plurality of substantially incompatible polyolefin-based resins or elastomers, and the incompatible polyolefin-based resin or elastomer forms a non-uniform distribution structure in the matrix. It is present, in particular, one of the incompatible polyolefin-based resins or elastomers is a propylene-based polymer and the other is an ethylene-based polymer, and particularly, the weight ratio of the propylene-based polymer to the ethylene-based polymer is 100. 7. 1 to 1: 1; 8. the oxygen absorbing layer has a thickness of 10 to 100 μm; 9. titanium dioxide is blended in the polyolefin buffer layer; A polyolefin buffer layer having a thickness of 5 to 50 μm,
Aluminum foil and stretched film have a thickness of 5 to 50 μm, or inorganic vapor-deposited plastic film has a thickness of 5 to 50 μm.
It preferably has a thickness of μm. According to the present invention, there is also provided a packaging bag comprising the above-mentioned oxygen-absorbing packaging material, particularly a packaging bag having the above-mentioned oxygen-absorbing packaging material on at least one surface. 10. The packaging bag of the present invention comprises: 11. using the oxygen-absorbing packaging material and a laminated packaging material of a polyolefin inner surface material / a stretched nylon film / an inorganic vapor-deposited polyester film, and heat sealing the polyolefin inner surface materials; It is preferable that the above-mentioned oxygen-absorbing packaging material and a transparent laminated packaging material composed of a polyolefin inner surface material / gas barrier layer / pinhole-resistant resin layer are used, and the polyolefin inner surface materials are heat-sealed to each other. According to the present invention, there is further provided a seal lid comprising the oxygen-absorbing packaging material.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Multilayer structure and operation of packaging material] In FIG. 1 showing an example of the oxygen-absorbing packaging material of the present invention, the oxygen-absorbing packaging material 1 is a polyolefin from the inside of the package to the outside of the package. Inner surface material 2, oxygen absorbing layer 3 composed of a composition of polyolefin and iron-based oxygen absorbent, polyolefin buffer layer 4, adhesive layer 5a, aluminum foil 6, adhesive layer 5b, stretched nylon and / or polyester film Of the outer surface layer 7 of FIG. In FIG. 2 showing another example of the oxygen-absorbing wrapping material of the present invention, the oxygen-absorbing wrapping material 1 includes a polyolefin inner surface material 2, a polyolefin and an iron-based oxygen absorbent, It comprises a laminate of an oxygen absorbing layer 3, a polyolefin buffer layer 4, an adhesive layer 5a, an inorganic vapor deposited layer 8, and an outer layer 9 of a plastic film. The oxygen-absorbing packaging material 1 of the present invention has a structure in which an oxygen-absorbing layer 3 made of a composition of a polyolefin and an iron-based oxygen absorbent is sandwiched between a polyolefin inner surface material 2 and a polyolefin buffer layer 4, Outside the polyolefin buffer layer 4, an aluminum foil 6 protected by an outer layer 7 of a stretched nylon or polyester film is stuck or an inorganic vapor-deposited plastic film 9 is coated with an inorganic vapor-deposited layer 8.
Are bonded together as the inner side.

In the present invention, in the oxygen-absorbing layer 3, the iron-based oxygen absorbing agent is present as the dispersed particle phase 11 in the polyolefin continuous phase 10, and the oxygen-absorbing performance is of course Depends on agent 11. The reason why the iron-based oxygen absorbent particles 11 are used in the form of a composition with the polyolefin 10 is to enable the oxygen absorbent particles 11 to be formed into a packaging material and to prevent the oxygen absorbent particles 11 from falling off.

In the present invention, the oxygen absorbing layer 3 is sandwiched between the polyolefin inner surface material 2 and the polyolefin buffer layer 4. This sandwich structure prevents the iron-based oxygen absorbent particles of the composition layer 5 from being exposed to the outer surface, and suppresses the cause of flavor reduction due to iron exposure and iron transfer in the initial stage of packaging from the stage of manufacturing the packaging material. It is effective for

In the present invention, the oxygen absorbent-containing resin composition layer 3 and the polyolefin layers 2 and 4 sandwiching the same are made of polyolefin because polyolefin has high oxygen permeability and excellent moisture resistance. It depends. That is, in the configuration of the packaging material, while the oxygen in the container permeates and moves to the iron-based oxygen absorbent via the polyolefin, there is an advantage that the direct contact between moisture and the iron-based oxygen absorbent is cut off. . Thus, in the packaging material of the present invention, oxygen absorption at the time of retort sterilization and at the initial stage of storage is extremely effectively performed by the above-described laminated structure (the present invention products 1 and 2 in Example 1 described later and the comparative product 1).
And 2).

An aluminum foil 6 or an inorganic vapor-deposited plastic film 9 protected by a stretched plastic layer 7 is coated on the outer surface side of the laminate comprising the polyolefin inner surface material 2 / oxygen absorbing layer 3 / polyolefin buffer layer 4 with a buffer layer 4
And the aluminum foil 7 or the inorganic vapor-deposited layer 8 are bonded in a positional relationship facing each other. If the aluminum foil 7 and the inorganic vapor deposition layer 8 are in a perfect state, oxygen permeation through the vessel wall can be suppressed to substantially zero. That is, in a gas barrier resin such as an ethylene vinyl alcohol copolymer, oxygen transmission occurs in a non-negligible order, whereas in an aluminum foil or an inorganic vapor-deposited layer, oxygen transmission can be almost completely suppressed ( (Compare the products 1 and 2 of the present invention with the control product 3 in Example 1 described later).

However, the aluminum foil and the inorganic vapor-deposited layer are weak to bend or protrude, and generate pinholes and cracks, so that oxygen is transmitted through the scratched portion. In the present invention, the outer surface of the aluminum foil is coated with a stretched nylon or polyester film, and in the case of an inorganic vapor-deposited plastic film, the inorganic vapor-deposited layer is inside, the plastic film is outside, and the aluminum foil or the inorganic vapor-deposited plastic By providing a buffer layer of polyolefin between the film and the oxygen absorbing layer,
This is to prevent the occurrence of pinholes and cracks in the aluminum foil and the inorganic vapor-deposited layer.

In a packaging material using an iron-based oxygen absorbent, the effect of volume expansion accompanying iron oxide formation after absorbing oxygen is large. For example, metallic iron particles react completely with oxygen,
When it comes to iron sesquioxide (Fe ₂ O ₃ ), the density of iron becomes 7.8.
Assuming that the density of the iron sesquioxide is 6 g / cm ³ and the density of the iron sesquioxide is 5.1 g / cm ³ , the volume expands about 1.6 times.
Therefore, by providing a polyolefin inner surface material on the inner surface side of the oxygen-absorbing agent-containing resin layer to prevent the iron oxide particles from being exposed on the inner surface side, in order to prevent a decrease in flavor of the contents due to elution of iron. It is important to provide a polyolefin buffer layer on the outer surface of the oxygen-absorbing resin-containing resin layer to prevent iron oxide particles from protruding into aluminum foil and inorganic vapor-deposited plastics. It becomes.

When titanium dioxide is blended with the polyolefin inner surface material, it is effective in concealing coloring by the iron-based oxygen absorbent and also effective in preventing iron oxide particles generated by oxygen absorption from protruding to the inner surface side. It is.

Further, the thermoplastic resin in which the oxygen absorbent is dispersed is formed from a blend of a plurality of substantially incompatible thermoplastic resins or elastomers, and the incompatible thermoplastic resin or elastomer is immiscible in the matrix. Forming a uniform distribution structure, particularly a multilayer distribution structure, is also effective in preventing the iron oxide particles from protruding toward the inner surface or the outer surface. That is, a blend of a plurality of substantially incompatible thermoplastic resins, when melt-molded, each component is distributed in layers, each layer overlaps in the thickness direction,
Each layer has a multilayer distribution structure extending in the plane direction. In this matrix structure, when particles composed of the oxidation reaction product of the oxygen absorbent undergo volume expansion, separation occurs at the interface of the non-uniform distribution structure, particularly the multilayer distribution structure, and a minute space (gap) is generated between the interfaces. The volume expansion of the particles made of the oxidation reaction product of the oxygen absorbent is absorbed by the minute space, and the destruction of the resin coating layer is completely prevented. It is preferable that one of the incompatible thermoplastic resins or elastomers, particularly the main component, is a propylene-based polymer and the other (a small amount of components) is an ethylene-based polymer. This combination is a general-purpose resin, and gives a combination excellent in phase separation without adversely affecting the moldability and mechanical properties of the resin. Further, in this combination, since the ethylene polymer has a lower melting point than the propylene polymer, an advantage that a fine non-uniform distribution structure can be formed is also provided.

As the iron-based oxygen absorber, it is preferable to use a reducing iron powder particle having a surface coated with an oxidation promoter or a catalyst layer on the surface thereof. In this oxygen absorber, since the accelerator or the catalyst is stably present on the surface of the iron powder particles, the moisture absorbed by the oxidation accelerator or the catalyst immediately activates the reducing iron powder, and the oxygen is reduced by the oxidation reaction of iron. The absorption proceeds, and the oxygen absorption rate is maintained at a high level. Further, the water absorbed by the oxidation promoter or the catalyst is also effectively used for the formation of hydrated oxides and the like, and the occurrence of swelling and cracks due to the water is effectively suppressed.

[Iron-based oxygen absorber] As the oxygen absorber used in the present invention, all iron-based oxygen absorbers conventionally used for this kind of application can be used. For example, ferrous oxide, triiron tetroxide, further reducing iron compounds, such as iron carbide, silicon iron, iron carbonyl, iron hydroxide and the like as a main component or the like, and these are mentioned. If necessary, use in combination with an alkali metal, alkaline earth metal hydroxide, carbonate, sulfite, thiosulfate, tertiary phosphate, secondary phosphate, organic acid salt, halide, etc. be able to.

The iron-based oxygen absorbent particles used in the present invention may be a blend of the reducing iron powder and the above-mentioned oxidation promoter or catalyst. However, the core particles of the reducing iron powder and the oxidizing agent coated on the core particles may be used. More preferably, it comprises a layer of a promoter or a catalyst. In addition, the oxidation promoter or the catalyst is used in an amount of 0.1 to 10% by weight, especially 0.1 to 5.0%, based on the reducing iron powder.
It should be present in an amount by weight.

In general, reducing iron powder is obtained by reducing iron oxide (for example, mill scale) obtained in a process of manufacturing iron ore or steel with coke, pulverizing sponge iron, and then reducing it in hydrogen gas or decomposed ammonia gas. Performing finish reduction, or electrolytically depositing iron from an aqueous solution of iron chloride obtained in the pickling process, pulverizing,
It is obtained by finish reduction. That is, iron oxides such as rust generated on the surface of the product in the steel manufacturing process are relatively pure, and the iron chloride obtained by pickling it is also pure. The reduction firing of iron oxide is generally performed at a temperature of about 600 to 1200 ° C.

The production of reducible iron is not limited to reduction calcination from the above pickled iron. If the raw material iron is pure, it is possible to spray molten iron into a non-oxidizing atmosphere or to use pure metallic iron. It can also be produced by grinding or steam pyrolysis of carbonyl iron.

From the standpoint of preventing the deterioration of the resin and improving the flavor retention, the reducing iron powder has a copper content of 150 ppm or less and a sulfur content of 50 ppm or less with respect to iron.
It is preferably 0 ppm or less.

Examples of the oxidation promoter or catalyst coexisting with the reducing iron powder include a water-soluble or deliquescent inorganic electrolyte. Specific examples thereof include sodium chloride, calcium chloride, zinc chloride, ammonium chloride, sodium iodide, potassium iodide, ammonium sulfate, sodium sulfate, magnesium sulfate, disodium hydrogen phosphate, sodium diphosphate, potassium carbonate, and sodium nitrate. And the like inorganic salts.

Of these, chlorides and iodides of alkali metals and alkaline earth metals, particularly sodium chloride, calcium chloride, sodium iodide and potassium iodide are preferred. In addition to these, manganese chloride (MnCl
_The use of a combination of manganese salts such as ₂ ) is also effective for absorbing oxygen by accelerating oxidation.

As the oxidation promoter, water-soluble organic compounds are also effective, such as glucose, fructose, sugar, gelatin, denatured casein, denatured starch, tragacanth gum, polyvinyl alcohol, CMC, sodium polyacrylate, and the like. Organic compounds such as sodium alginate are exemplified. These organic oxidation promoters or catalysts may be blended with the thermoplastic resin in the form of oxygen absorbent particles, or may be blended with the resin separately from the oxygen absorbent particles. It goes without saying that a plurality of oxidation promoters or catalysts can be used in combination.

The reducing iron powder and the oxidation promoter or catalyst are combined in the quantitative ratio already described in detail. When coating the surface of the reducing iron powder with the oxidation promoter or the catalyst, the reduction iron powder and the powder of the oxidation promoter or the catalyst are milled in a solid phase dry system. The end point of the dry milling can be known from the fact that free solid particles of the oxidation promoter or the catalyst cannot be confirmed by an electron microscope.
For dry milling, a vibration mill, a ball mill, a tube mill, a super mixer, or the like can be used. Although the oxygen absorbent particles obtained after the dry milling are not generally required, the free oxidation promoter or the fine powder of the catalyst may be separated and removed by an operation such as sieving or air classification.

The iron-based oxygen absorbent has a median particle diameter of 10 to 50 microns as measured by a laser scattering method, and the aspect ratio (minor axis / major axis) of 0.75 or less is 50% or more. It is preferred that the spindle or flat particles occupy the space. Further, the BET specific surface area is 0.5 m ² / g or more,
Those having an apparent density of 2.2 g / cc or less are preferred.

[Oxygen Absorbing Layer] The oxygen absorbing layer used in the present invention comprises the above-mentioned iron-based oxygen absorbent dispersed in polyolefin. It is preferable to disperse 2 to 60 parts by weight of the iron-based oxygen absorbent per 100 parts by weight of the polyolefin. If the amount of the iron-based oxygen absorbent is less than the above range, the oxygen-absorbing ability becomes insufficient. If the amount exceeds the above range, the moldability of the compounded composition will be reduced, or the above-mentioned troubles accompanying volume expansion after oxygen absorption will easily occur.

Examples of the polyolefin include low-, medium- or high-density polyethylene, linear low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, linear low-density polyethylene,
Ethylene-propylene copolymer, polybutene-1, poly4-methyl-1-pentene, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene -Vinyl acetate copolymers, ion-crosslinked olefin copolymers (ionomers), ethylene-acrylate copolymers, and the like. These can be used alone or in the form of a blend of two or more.

From the viewpoint of heat resistance to retort sterilization,
A crystalline propylene-based polymer is suitable, and a homopolypropylene or a random copolymer or a block copolymer mainly composed of propylene under the condition of being crystalline is used. The propylene polymer used is 0.8 to 1
2g / 10min melt flow rate (JIS K6
758).

In a preferred embodiment of the present invention, the propylene-based polymer and the ethylene-based polymer are mixed and used in a weight ratio of 100: 1 to 1: 1, particularly 50: 1 to 3: 2. .

The thickness of the oxygen absorbent-containing resin layer is preferably in the range of 10 to 100 μm, particularly 15 to 60 μm. If the thickness is less than the above range, the oxygen absorbing ability tends to be insufficient. On the other hand, if the thickness is more than the above range, the moldability deteriorates and the flexibility and flexibility as a packaging material tend to decrease.

[Polyolefin inner surface material] As the polyolefin inner surface material, the polyolefin described for the oxygen absorbing layer is used. In terms of interlayer adhesion between the inner surface material and the oxygen absorbing layer, it is desirable that the polyolefin of the inner surface material and the polyolefin of the oxygen absorbing layer be of the same type. It is desirable to blend a white pigment, particularly titanium dioxide, in the polyolefin inner surface material for the purpose of concealing coloring by the oxygen absorbent. The amount of titanium dioxide is not particularly limited, but is suitably in the range of 5 to 25 parts by weight per 100 parts by weight of polyolefin.

The thickness of the polyolefin inner surface material is 5 to 5
It is preferably in the range of 0 μm, especially 10 to 30 μm.
When the thickness is less than the above range, iron oxide particles generated by oxidation tend to protrude, and the flavor tends to decrease. On the other hand, when the thickness exceeds the above range, the oxygen absorption tends to decrease.

[Polyolefin buffer layer] As the polyolefin buffer layer, the polyolefin described for the oxygen absorbing layer is used. From the viewpoint of interlayer adhesion between the buffer layer and the oxygen absorbing layer, it is desirable that the polyolefin of the buffer layer and the polyolefin of the oxygen absorbing layer be of the same type.

The thickness of the polyolefin buffer layer is 5 to 5
It is preferably in the range of 0 μm, especially 10 to 30 μm.
If the thickness is below the above range, the iron oxide particles generated by oxidation may protrude into the aluminum foil or the like, and the oxygen barrier property tends to decrease, whereas if the thickness exceeds the above range, the moldability deteriorates. Along with the flexibility as a packaging material,
Flexibility tends to decrease.

[Aluminum foil] As the aluminum foil, all aluminum foils used for this kind of packaging can be used. For example, pure aluminum or a small amount of aluminum and other alloying metals, especially magnesium, manganese, etc. Aluminum alloy is used. This aluminum foil may be any of those generally called soft, hard or semi-hard. The thickness of the aluminum foil is preferably in the range of 5 to 50 μm, especially 7 to 20 μm. When the thickness is less than the above range, oxygen barrier properties tend to be insufficient, while when the thickness is more than the above range, flexibility and flexibility as a packaging material tend to decrease.

[Stretched Film Layer] As the stretched film used for protecting the aluminum foil, a stretchable film-forming thermoplastic resin can be used. In particular, suitable thermoplastic resins include nylon, polyester and the like. As the nylon film (Ny), nylon 6, nylon 6,6, nylon 6 / 6,6 copolymer, nylon 1
0, nylon 12, or a blend thereof. On the other hand, as the polyester film, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN)
Alternatively, a blend of these and the like can be mentioned. These films are preferably stretched in at least one uniaxial direction, and biaxially stretched films are best. The stretched film needs to be provided on the outer surface of the aluminum foil (Al), but may be provided on the inner surface of the aluminum foil. A suitable example of a laminated structure is Al / P
ET, Al / Ny, Al / Ny / PET, Al / PET
/ Ny. The thickness of the stretched film layer is 5 to 5
It is preferably in the range of 0 μm, especially 10 to 25 μm.
When the thickness is less than the above range, the protective effect on the aluminum foil is insufficient. On the other hand, when the thickness is more than the above range, the flexibility as a packaging material and the flexibility tend to decrease, and also in terms of cost. Disadvantageous.

[Inorganic vapor-deposited plastic film] In the present invention, an inorganic vapor-deposited plastic film can be used in place of the combination of the aluminum foil and the stretched film. An inorganic vapor-deposited plastic film is formed by depositing an inorganic substance, that is, a ceramic such as silicon oxide or alumina, carbon, or the like, on a surface of a plastic film substrate by chemical vapor deposition (CVD), a vacuum deposition method, a sputtering method, an ion plating method, or the like. Although the thickness of the deposited layer is as thin as 50 to 1000 angstroms, it exhibits excellent barrier properties against oxygen and the like. As the plastic film substrate, the above-mentioned stretched nylon film, stretched polyester film and the like are suitable, but a stretched polypropylene film can also be used. It is advantageous in terms of handling that the thickness of the stretched film formed by inorganic vapor deposition is in the range of 5 to 50 μm, particularly 10 to 30 μm.

[Laminate] The laminate used for the packaging material in the present invention is prepared by first preparing a preliminary laminate comprising a polyolefin inner surface material / an oxygen absorbing layer comprising a composition of a polyolefin and an iron-based oxygen absorbent / a polyolefin buffer layer. Then, the laminated body and (1) a laminated body of an aluminum foil and a stretched film, or (2) an inorganic-deposited plastic film are joined in a positional relationship in which the buffer layer and the aluminum foil or the inorganic-deposited layer face each other. It is manufactured by doing. When the plastic film substrate (base film) of the inorganic vapor-deposited plastic film is made of polyester, it is particularly preferable that stretched nylon is provided between the buffer layer and the inorganic vapor-deposited layer of the inorganic vapor-deposited plastic film. It is preferable for improving the pinhole property.

The above pre-laminate is preferably produced by co-extrusion. The number of extruders according to the type of the resin is used to extrude the corresponding resin in a multi-layer die. For the film formation, an inflation film formation method or a T-die film formation method can be used. In the former case, a ring die is used, and in the latter case, a flat die is used. Also,
Of course, it is also possible to manufacture a laminate by a sandwich lamination method in which a molten resin is extruded between two prepared layers to obtain a laminate. In the sandwich lamination method, specifically, an extruder and a die lip are arranged between two lamination rolls, two layers supported by each lamination roll are supplied between the rolls, and a molten resin is extruded between these layers. The laminate is formed at the nip position between the rolls. It goes without saying that the multilayer film can be stretched during film formation. The thickness of the three-layer film is 30 to 300 μm
It is good to be in the range.

When a combination of an aluminum foil and a stretched film is used, the aluminum foil and the stretched film can be bonded in advance with an adhesive, which can be bonded with a preform and an adhesive, or can be pre-laminated. An aluminum foil and a stretched film can be sequentially attached to the body in this order.

When an inorganic vapor-deposited plastic film is used, the inorganic vapor-deposited film and the preliminary laminate may be bonded with an adhesive.

For adhesion lamination, so-called dry lamination can be used, and for this purpose, a thermosetting adhesive resin such as an isocyanate-based or epoxy-based resin can be used. Of course, an adhesive made of a thermoplastic resin can also be used, for example, carboxylic acid, carboxylic anhydride, carboxylate, carboxylic amide, carboxylic ester, and the like. In the main chain or side chain, from 1 to 700 milliequivalent (meq) / 100 g resin, especially from 10 to 500 meq / 10
A thermoplastic resin containing 0 g resin is used.
Suitable examples of thermoplastic adhesive resins include ethylene-acrylic acid copolymer, ionic cross-linked olefin copolymer, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, acrylic acid-grafted polyolefin,
Ethylene-vinyl acetate copolymer, copolyester,
One or a combination of two or more such as copolymerized polyamide.

The laminate can also be produced by an extrusion coating method. That is, the above-mentioned preliminary laminate may be melt-extruded on (1) a laminate of aluminum foil and stretched nylon and / or polyester, or (2) on an inorganic vapor-deposited plastic film to form a final laminate. At the time of this extrusion coating, in order to improve the adhesiveness,
An anchor agent such as urethane or titanate can be applied.

[Use] The packaging material of the present invention can be used as a flexible packaging material for containers such as various packaging bags and flexible lid materials. Examples of the form of the packaging bag include, but are not limited to, ordinary pouches, gusseted pouches, standing pouches, and pillow packaging bags with a three- or four-side seal. In addition, as a lid material, it can be used as a seal lid for containers such as cups and trays. When the oxygen-absorbing packaging material of the present invention is used for packaging containers, especially pouches, one or both surfaces can be formed of the oxygen-absorbing packaging material. In addition, one surface is formed of an oxygen-absorbing packaging material, and the other surface is formed of a transparent laminated packaging material having a polyolefin inner surface material, a gas barrier layer, and a pinhole-resistant resin layer. The material and the transparent laminated packaging material may be overlapped so that the polyolefin inner surface materials face each other, and the periphery may be heat-sealed to form a packaging container. As the polyolefin inner surface material, those already described are used. As the gas barrier layer, the aforementioned inorganic vapor-deposited layer or nylon stretched film layer is used, and as the pinhole-resistant resin layer, the aforementioned stretched film layer is used. The inorganic vapor-deposited plastic film layer achieves both pinhole resistance and gas barrier properties by using the film on the outer surface side. Generally, the oxygen absorbent is in the form of opaque particles, so that the oxygen-absorbing packaging material containing the oxygen-absorbing material has poor transparency. Absorbency and gas barrier properties are provided by the oxygen-absorbing packaging material on one side, while contents transparency and gas barrier properties are provided by the transparent laminated packaging material on the other side, so that all requirements can be satisfied. Become. In FIG. 3 showing an enlarged cross section of this type of container (a heat seal portion is omitted), one side of the pouch content 12 is directed from the inside of the pouch to the outside of the pouch,
A polyolefin inner surface material 2, an oxygen absorbing layer 3 made of a composition of polyolefin 10 and an iron-based oxygen absorbent 11, a polyolefin buffer layer 4, an adhesive layer 5a, an aluminum foil 6,
An oxygen-absorbing wrapping material comprising an adhesive layer 5b and an outer layer of the stretched polyester film 7 was used, and the other surface of the polyolefin inner surface material 2, the adhesive layer 5b was stretched from the inside of the pouch to the outside of the pouch. A packaging material including a nylon film 7, an adhesive layer 5a, an inorganic vapor-deposited layer 8, and a stretched polyester film 9 may be used.

The packaging material of the present invention is useful for hermetic preservation of foods in which flavor retention and hue retention are important, for example, tomato-based foods, processed foods such as soups, stews, curries, and coffee. , Tea and other beverages, fruits, juices and other fruits, fruit juice products, salami sausage,
It is useful for preserving meat products such as ham, marine products such as tuna oil pickles, kabayaki, and kamaboko, and foods containing functional ingredients such as EPA and DHA. Furthermore, it is also effective for preservation of pharmaceuticals and cosmetics which are susceptible to oxidative deterioration and contamination by microorganisms, such as amino acid preparations, fat emulsions, circulatory failure improving agents containing dopamine hydrochloride, and various vitamin-containing packs. When packing the contents into the container containing the present oxygen-absorbing packaging material, a further effect can be obtained by using a gas replacement packaging technique using an inert gas such as nitrogen.

[0054]

The present invention is further described in the following examples.

Example 1 A polypropylene resin (PP) having a melt index (MI, 230 ° C., 10 minutes) of 2.5 was mixed with an average particle size of 20.
μm iron-based oxygen absorber per 10 parts by weight of resin
A three-layer film was prepared by an inflation method using the oxygen-absorbing resin composition (PO) blended in the ratio of parts as the intermediate layer, and the layers on both sides thereof being the same PP. At this time, one of the PP layers was blended with a titanium oxide pigment and turned white. Layer structure: white PP layer / PO layer / PP layer = 20/25
/ 20 (μm). A 7 μm aluminum foil and a further 12 μm polyethylene terephthalate (PET) film are laminated on the PP layer side of this layer using an adhesive, and a white PP
An oxygen-absorbing laminated film of / PO / PP / adhesive / Al / adhesive / PET was prepared (Product 1 of the present invention). In addition, a product using an aluminum oxide-deposited PET film instead of the aluminum foil / adhesive / PET film was also prepared (Product 2 of the present invention). As a control, a laminated film of the same configuration except that there is no PO layer (controls 1 and 2), and an ethylene-vinyl alcohol copolymer (Eval resin, Kuraray) which is an organic barrier film instead of the aluminum foil of the present invention. The used one was prepared (Control 3).
Using these films, bags were sealed on three sides of 150 × 170 mm. 200m of distilled water in this bag
l, and the space in the bag (head space) is 15ml
And sealed. After the retort treatment at 120 ° C. for 30 minutes, it was stored at 30 ° C.-80%, and the oxygen concentration in the bag was measured at regular intervals. Table 1 shows the measurement results. Table 1 Results Oxygen concentration in bag (%) Retort 14 days 30 days 60 days immediately after 180 days Product of the present invention 1 6.5 0.3 0.1 0.1 0.1 Product of the present invention 2 7.0 0.5 0.2 0.1 0.1 Control 1 20.8 20.8 20.8 20.8 20.8 Control 2 20.8 20.8 20.8 20.8 20.8 Control 3 7.2 0.9 0.3 0.1 1.2 1.2 The control products 1 and 2 without the PO layer did not change the oxygen concentration in the bag. In Control 3, although the oxygen concentration in the bag decreased,
Long-term storage showed an increase in oxygen concentration.

Example 2 A polypropylene resin (PP) having a melt index (MI, 230 ° C., 10 minutes) of 30 was mixed with an average particle size of 20 μm.
m of the iron-based oxygen absorber was blended in a ratio of 10 parts by weight with respect to 100 parts by weight of the resin to prepare an oxygen-absorbing resin composition. Then, a 12 μm-thick polyethylene terephthalate (PE
T) film / adhesive / aluminum foil 7 μm thick /
The oxygen absorbing property between both polypropylene film layers of a laminate composed of an adhesive / polypropylene (PP) film having a thickness of 20 μm and a white polypropylene (PP) film having a thickness of 30 μm containing a titanium dioxide pigment. The composition was melt-extruded to produce an oxygen-absorbing film similar to that of Example 1 by a sandwich lamination method (similar to Product 1 of the present invention). Further, a film using an aluminum oxide-deposited PET film instead of the polyethylene terephthalate (PET) film / adhesive / aluminum foil was also prepared (similar to the product 2 of the present invention). Using these laminates, a bag similar to that of Example 1 was formed, and the oxygen concentration was measured. As a result, excellent oxygen absorption capacity was exhibited as in Example 1.

Example 3 A bag similar to the product 1 of the present invention in Example 1 was filled with 180 g of salsa sauce, beef curry and coffee having the following formulation, and sealed by heat sealing. The remaining air volume in the bag is about 15c
c. After sterilization treatment at 120 ° C for 30 minutes, it was stored in an environment of 30 ° C and 80%. A sensory test was performed two weeks after storage and one month after storage. 10 panels,
Evaluation was made out of 5 points. Table 2 shows the evaluation results. A similar test was performed using a bag having the same configuration as the control product 1 in Example 1 as a comparative product.

Table 2 Sensory test results 2 weeks 1 month Invention product 1, Control product 1 Invention product 1, Control product 1 Salsa sauce 4.6 4.0 4.5 3.2 Beef curry 4.8 4 4.1 4.6 3.5 Coffee 4.1 3.8 3.8 3.0 In all tests, the product of the present invention showed excellent storage performance.

<Method for Preparing Contents> 1 Salsa Sauce Pepper, tomato and onion were minced, and salt, lemon juice and garlic were added in appropriate amounts. 2 Coffee Boiling mineral water was poured into 72 g of blue ground mountain that was ground into a medium, steamed for 1 minute, and then 1.3 l was poured to extract a coffee liquid. 3 Beef curry Roasted and frozen medium meat (1.5 cm square) was thawed and reheated. Potatoes and carrots cut to a predetermined size and frozen were thawed and then desalted. The cut, roasted and frozen onions were thawed and heated again. For 100 g of beef, potato 75, carrot 50, onion 50, curry roux 6
The curry was adjusted by mixing at a ratio of 00.

Example 4 The product 1 of the present invention and the control product 1 of Example 1 were used as a heat-sealable base material of a flanged steel foil laminated cup (Hiretoflex, can made by Toyo) containing pineapple syrup. Sealing was performed under a nitrogen gas atmosphere, and the space (head space) in the container was 20 cc. 90
The mixture was sterilized with hot water at 20 ° C. for 20 minutes, and then stored at 30 ° C. After storage for a certain period, the color of the pineapple was measured. The measurement was carried out using a color machine type I manufactured by Suga Test Instruments, and the hue (H)
I asked. The product of the present invention was almost the same as the initial product, but the control product showed a change in hue.

[0061]

Example 5 A control product 4 having the same structure as that of the product 1 of the present invention of Example 1 except that the blending amount of the oxygen absorbent in the intermediate layer was 70% was prepared. The product 1 of the present invention and the control product 4 were sealed in three sides, filled with 180 ml of water, and then retorted at 120 ° C. for 30 minutes. After storing at 30 ° C. and 80% for one month, the appearance of the packaging material and the lamination strength of the packaging material were measured. The product of the present invention had a smooth surface of the packaging material and was superior to the control product. Also, the lamination strength was 1.0 kg /
cm ² whereas the control was 0.2 kg / cm ² .

Example 6 A bag having the same composition and composition as the product 1 of the present invention of Example 1,
The resin composition of the oxygen-absorbing intermediate layer was changed to a polypropylene-based resin of MI1.2 and a low-density polyethylene (LD of MI1.0).
PE) (7: 3) (product 3 of the present invention). The bag was filled with 180 ml of water and stored at 50 ° C. for 6 months. After storage for 6 months, the amount of iron in the water was measured by the atomic absorption method. No iron was eluted in the product 3 of the present invention. The product 3 of the present invention is excellent in the robustness of the container.

Example 7 The same composition and composition as the product 1 of the present invention of Example 1, except that the iron-based oxygen absorbent in the oxygen-absorbing intermediate layer has sodium chloride adhered to the surface of iron particles. A bag was prepared (Product 4 of the present invention). 180 ml of water was put in this bag, and the same test as in Example 4 was performed. No iron was detected in the bag of the product 4 of the present invention.

Example 8 A 15 μm-thick stretched nylon 6 film was bonded to the vapor-deposited side of a 12 μm-thick silicon oxide (SiOx) vapor-deposited stretched PET film via a urethane-based adhesive, and further to the nylon film side. A transparent laminated packaging material was obtained by bonding a polypropylene film having a thickness of 60 μm. This transparent laminated packaging material and the oxygen-absorbing packaging material of the first embodiment (product 1 of the present invention) are overlapped so that the polypropylene inner facing materials face each other, and the periphery thereof is heat-sealed to form a pouch-shaped packaging container. did. This container was excellent in the transparency of the contents and also excellent in the oxygen absorption as in the case of the product 1 of the present invention.

[0066]

According to the present invention, the polyolefin inner surface material / oxygen absorbing layer / polyolefin buffer layer composed of a composition of polyolefin and iron-based oxygen absorbent, aluminum foil / stretched film, or inorganic vapor-deposited plastic film are sequentially formed. By using the laminated product as a packaging material, an oxygen-absorbing packaging material exhibiting excellent content preservability and flavor retention even after long-term storage after retort sterilization is provided. The packaging material of the present invention has an advantage in that, even during long-term storage after retort sterilization, oxidation deterioration due to oxygen in the packaging and flavor reduction due to elution of iron are suppressed.
In addition, by using the oxygen-absorbing packaging material on one surface and using the transparent laminated packaging material on the other surface, it is possible to simultaneously achieve excellent contents transparency while achieving the above effects.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a cross-sectional structure of a laminate used for a packaging material of the present invention.

FIG. 2 is a cross-sectional view showing another example of the cross-sectional structure of the laminate used for the packaging material of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a packaging container of the present invention in which one surface is formed of an oxygen-absorbing packaging material and the other surface is formed of a transparent laminated packaging material.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B65D 81/26 B65D 81/26 SF term (reference) 3E067 AA03 AA04 AA11 AB01 AB02 AB04 AB24 AB26 AB81 BA12A BB12A BB14A BB15A BB16A BB18A BB22A BB23A BB25A BC07A EE25 EE32 GB13 GD02 4F100 AA01D AA21A AA21C AB02A AB10C AB33C AK01D AK03A AK03B AK03C AK04A AK07A AK41D AK46D AK46E AL05B AL09A BA04 BA05 BA07 BA10A BA10D BA13 BA44 CA09B CA30A DE01A EH66D EJ37D EJ37E GB15 GB17 GB18 JB04A JD14B JK11C JL00 JL08A YY00A YY00C

Claims (20)

[Claims] An oxygen absorbing layer / polyolefin buffer layer comprising a composition of a polyolefin inner surface material / polyolefin and an iron-based oxygen absorbing agent, and an aluminum foil / stretched film,
Alternatively, an oxygen-absorbing packaging material, wherein inorganic vapor-deposited plastic films are sequentially laminated. 2. The oxygen-absorbing packaging material according to claim 1, wherein the stretched film is a nylon film. 3. The oxygen-absorbing packaging material according to claim 1, wherein the stretched film is a polyester film. 4. The oxygen-absorbing packaging material according to claim 1, wherein the stretched film is a laminated film of a nylon film and a polyester film. 5. The oxygen-absorbing packaging material according to claim 1, further comprising a stretched nylon film between the polyolefin buffer layer and the inorganic vapor-deposited plastic film. 6. The oxygen-absorbing packaging material according to claim 1, wherein titanium dioxide is blended in the polyolefin inner surface material. 7. The polyolefin inner surface material has a thickness of 5 to 50 μm.
The oxygen-absorbing packaging material according to any one of claims 1 to 6, having a thickness of: 8. The oxygen-absorbing packaging material according to claim 1, wherein the oxygen-absorbing layer contains 2 to 60 parts by weight of an iron-based oxygen absorbent per 100 parts by weight of the polyolefin. 9. The iron-based oxygen absorbent comprises a reducing iron powder and an oxidation promoter or a catalyst coated on the surface of the reducing iron powder, and the oxidation promoter or the catalyst is contained in an amount of 0 per reducing iron powder. An oxygen-absorbing wrapping material according to any of the preceding claims, wherein it is present in an amount of from 1 to 10% by weight. 10. The oxygen-absorbing layer, wherein the polyolefin is a matrix comprising a blend of a plurality of substantially incompatible polyolefin resins or elastomers, wherein the incompatible polyolefin resins or elastomers are non-uniformly distributed in the matrix. The oxygen-absorbing packaging material according to any one of claims 1 to 9, wherein the packaging material has a structure. 11. The oxygen-absorbing packaging material according to claim 10, wherein one of the incompatible polyolefin-based resin or elastomer is a propylene-based polymer and the other is an ethylene-based polymer. 12. The propylene polymer and the ethylene polymer in a weight ratio of 100: 1 to 1: 1.
2. The oxygen-absorbing packaging material according to item 1. 13. The oxygen-absorbing packaging material according to claim 1, wherein the oxygen-absorbing layer has a thickness of 10 to 100 μm. 14. The oxygen-absorbing packaging material according to claim 1, wherein titanium dioxide is blended in the polyolefin buffer layer. 15. The polyolefin buffer layer has a thickness of 5 to 50 μm.
m, aluminum foil and stretched film are 5 to 5
The oxygen-absorbing packaging material according to any one of claims 1 to 14, wherein the thickness is 0 µm or the thickness of the inorganic vapor-deposited plastic film is 5 to 50 µm. A packaging bag comprising the oxygen-absorbing packaging material according to any one of claims 1 to 15. 17. A packaging bag having the oxygen-absorbing packaging material according to claim 1 on at least one surface. 18. The heat-sealing of polyolefin inner surfaces using the oxygen-absorbing packaging material according to claim 1 and a laminated packaging material of polyolefin inner surface material / stretched nylon film / inorganic vapor-deposited polyester film. Packaging bag. 19. A polyolefin inner surface material comprising: the oxygen-absorbing packaging material according to claim 1; and a transparent laminated packaging material comprising a polyolefin inner surface material / gas barrier layer / pinhole-resistant resin layer. A packaging bag that heat seals each other. 20. A seal lid comprising the oxygen-absorbing packaging material according to claim 1.