JP2000015730A - Wall member of package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive wall member preventing the transmission of oxygen from the outside and the transmission of nitrogen or carbon dioxide from the inside in a package packing perishable foods or a beverage and requiring the purging by inert gas such as nitrogen at the time of filling with content. SOLUTION: A wall member 1 of a package is constituted by laminating at least one foamed resin layer 20 foamed by gas to be filled therewith to resin layers 10 excellent in barrier properties between them or laminating the same to the single surface of one resin layer 10 and the gas is a single inert gas such as nitrogen or carbon dioxide or mixed gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic film for packaging fresh foods and beverages such as vegetables and fruits,
The present invention relates to a package comprising a sheet and a bottle, and more particularly to a wall of a package which needs to be purged with an inert gas such as nitrogen or carbon dioxide when filling the contents.

[0002]

2. Description of the Related Art Conventionally, when filling contents such as fresh foods and beverages which are not liable to be oxidized by oxygen, it is necessary to remove oxygen remaining in a space between the packing material and the contents after filling the contents. In addition, it is known to replace with an inert gas such as nitrogen or carbon dioxide, or to put an oxygen absorbent together with the contents and heat seal to form a package.

Further, after filling and sealing, in order to suppress the permeation of the substituted nitrogen and carbon dioxide from the inside of the package or the permeation of oxygen from the outside of the package, a packing material having excellent gas barrier properties may be used. Oxygen absorbents have been used to remove oxygen that has passed through the packaging material.

[0004] However, the above-mentioned method using an oxygen absorbent is excellent in that oxygen can be completely removed. However, in addition to the high cost of the oxygen absorbent, the oxygen absorbent has a high ability to absorb oxygen. However, there is a problem that a large amount of an oxygen absorbent must be used for long-term storage, which further increases the cost.

[0005] In addition to this, if the oxygen absorbent is left unattended, handling is troublesome such that oxygen is immediately absorbed and cannot be used, and the oxygen absorbent does not appear unless there is some moisture. Therefore, this method has a limited use.

In the method using a packaging material having excellent barrier properties against oxygen and water vapor in the atmosphere, for example, even a packaging material having excellent barrier properties such as polyethylene terephthalate (PET) is not completely zero in gas barrier properties. For this reason, there is a problem in that there is some permeation of oxygen, nitrogen, carbon dioxide, and the like, and the contents are spoiled and discolored due to oxidative deterioration of the contents.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a plastic film for packaging fresh foods such as vegetables and fruits, beverages, and the like. A package consisting of sheets and bottles that requires purging with an inert gas such as nitrogen or carbon dioxide when the contents are filled, so that there is no permeation of oxygen from the outside and permeation of nitrogen and carbon dioxide from the inside It is an object of the present invention to provide an inexpensive package body without a wall.

[0008]

In order to achieve the above-mentioned object in the present invention, first, according to the first aspect of the present invention, there is provided a method in which a gas bubble is formed between resin layers having excellent barrier properties or on one surface thereof. A wall of a package characterized by laminating one or more resin layers.

Further, according to the invention of claim 2, the gas is:
2. The foam resin layer is filled.
It is a wall of the described package.

[0010] In the invention of claim 3, the gas is:
3. A wall of a package according to claim 1 or 2, which is a simple gas of an inert gas such as argon, helium, water vapor, nitrogen or carbon dioxide or a mixed gas thereof.

Further, according to the invention of claim 4, the gas is:
The package body according to claim 1 or 2, which is a simple gas of a gas such as ethylene or methane that promotes plant growth or a mixed gas thereof.

[0012]

Embodiments of the present invention will be described below. As shown in FIG. 1, the package of the present invention is provided between resin layers (10) having excellent barrier properties, or as shown in FIG. 2, the inner surface (10a) of the resin layers (10) having excellent barrier properties. )
And a wall (1) of a package formed by laminating one or more foamed resin layers (20) foamed with a gas. The foamed resin layer (20) is filled with a gas used for foaming. It is characterized by becoming.

Further, the invention according to claim 3 is characterized in that the gas is a single gas of an inert gas such as argon, helium, water vapor, nitrogen or carbon dioxide or a mixed gas thereof.

Specifically, the above gas may be an inert gas such as argon or helium, but may be a simple gas of nitrogen or carbon dioxide, a mixed gas of nitrogen or carbon dioxide and water vapor, or a gas mixture of nitrogen or carbon dioxide. Or a mixed gas of nitrogen, carbon dioxide and water vapor, the wall (1) of an inexpensive and practical package can be obtained.

As described above, as a gas for forming the foamed resin layer (20), an inert gas such as nitrogen and carbon dioxide;
That is, by using the same inert gas as the inert gas filling the space between the contents and the packaging material, the foamed resin layer (20) is filled with the inert gas,
Further, in order to retain the inert gas of the foamed resin layer (20), the front and back or one surface of the foamed resin layer (20) is protected by a resin layer (10) having excellent barrier properties.

This is substantially the same as providing a single layer of an inert gas such as nitrogen, and it is difficult for the same inert gas to pass through the inert gas layer. The shelf life of beverages and foods can be further extended.

Further, the invention according to claim 4 is characterized in that the gas is a simple gas of a gas such as ethylene or methane which promotes the growth of a plant or a mixed gas thereof, wherein the gas which promotes the growth of the plant is used. Examples thereof include ketone, acetaldehyde, acetone and the like in addition to the above-mentioned commonly used ethylene and methane.

That is, contrary to the effect of extending the expiration date with the above-mentioned inert gas, for example, by providing a gas layer such as ethylene which promotes the growth of plants, it is possible to quickly ripen melons and bananas. Can be.

Specifically, a foamed resin layer (20) foamed using foamed beads using ethylene as a gas is sandwiched between resins having a high barrier property, and after filling with melon or the like, sealing is performed.
Damage the resin layer (10) having an excellent barrier property as an inner layer,
After the melon or the like is filled, the melon or the like can be quickly ripened by diffusing the ethylene gas into the inside.

Examples of the resin used in the resin layer (20) having excellent barrier properties according to the present invention include saponified ethylene vinyl acetate copolymer (EVOH), polymethaxylylene azimide (MXNy), polyamide (PA), and polyethylene (PA). Examples include, but are not limited to, naphthalate (PET).

The method of forming the foamed resin layer (20) basically differs depending on the type of gas for forming the foamed resin layer (20). Can be used.

For example, if the gas for forming the foamed resin layer (20) is carbon dioxide, nitrogen, or the like, the gas is the same as the gas generated by the chemical foaming, so that the chemical foaming method can also be used. The chemical foaming method uses gas generated by a chemical reaction as a foaming agent. Specifically, a reaction between sodium carbonate and citric acid generates carbon dioxide and water, and a decomposition of azodicarbonamide. The gas generated by the reaction of generating nitrogen due to the above is used as a foaming agent and is held in the foamed resin layer (20).

As another method, there is a foamed bead method, and there is no limitation on a gas used for foaming, and a gas suitable for various uses of the present invention can be selected, and thus it can be preferably used. That is, this expanded bead method
The gas used to fill the beads used for foaming is not particularly limited to gases such as carbon dioxide, nitrogen, argon, neon, oxygen, chlorine, methane, and normal butane.

The foamed resin layer (20) according to the present invention
Any resin can be used as long as it can be a chemical foaming method or a bead foaming method generally used to form a foamed plastic, and specifically, a thermoplastic resin such as polystyrene, polyethylene, polypropylene, or polyester. However, the present invention is not limited to this. As the resin physical properties of the foamed resin layer (20), a resin having a high resin viscosity and a small temperature change of the viscosity is preferable.

It is also possible to use a saponified ethylene-vinyl acetate copolymer, polymetaxylylene azimide, polyamide, polyethylene naphthalate or the like having good gas barrier properties as the resin of the foamed resin layer (20). In such a case, as shown in FIG.
Resin layer (10) having excellent gas barrier properties only on the outer surface of (0)
Or, in an extreme case, only the foamed resin layer (20).

The foamed resin layer (20) can be molded by a usual molding machine such as an ordinary injection molding machine, blow molding machine or extrusion molding machine, but is extruded or injected. It is preferable to perform processing using a molding machine that can minimize the temperature fluctuation of the resin, because the foamed cells become uniform. When the foamed resin layer (20) is extruded by an extruder, the shape of the die is preferably straight without bending as much as possible.

[0027]

Next, the present invention will be described in detail with reference to examples. <Example 1> As shown in FIG. 1, the outer layer and the inner layer of the resin layer (10) having excellent gas barrier properties were saponified with ethylene vinyl acetate copolymer (EVOH), and the intermediate layer was foamed with ethylene as the foaming gas. A foamed resin layer (20) in which polyethylene (PE) is foamed by beads is extruded by co-extrusion, and a wall of a package comprising a foamed resin layer (20) containing EVOH in an outer layer and an inner layer and ethylene gas in an intermediate layer. A laminated film of (1) was obtained.

The thickness of the three-layer film obtained above is 5 μm for both the outer layer and the inner layer as the resin layer (10) having excellent barrier properties, and the foamed resin layer (20) as the intermediate layer.
Was 50 μm to 60 μm.

Using this laminated film, bananas are inserted as contents and heat-sealed, and the EVOH layer serving as the inner surface is damaged during heat-sealing to form a bag, whereby the bag is filled with ethylene gas of the foamed resin layer (20). However, it was confirmed that the banana ripened faster than the one made in contact with the banana and made without using the foam layer.

Example 2 As shown in FIG. 1, polymetaxylylene azimide (MXNy) was used for both the outer and inner layers as the resin layer (10) having excellent barrier properties, and azodicarbonamide was used as the foaming agent for the intermediate layer. Polypropylene (P
A foamed resin layer (20) obtained by foaming P) is extruded by co-extrusion to obtain a laminated film as a wall (1) of a package made of foamed PP containing MXNy in an outer layer and an inner layer and nitrogen gas in an intermediate layer. Was.

The thickness of the three-layer film obtained above is 5 μm for the outer and inner layers, and 50 μm to 60 μm for the intermediate layer.
m.

Using this film, oil was added as a content, and a bag was formed by filling with nitrogen gas during heat sealing. The oil in the bag was less oxidatively degraded and could be stored for a long period of time as compared with a conventional bag-made product without the foamed resin layer (20) filled with oil.

Example 3 As shown in FIG. 1, the outer layer and the inner layer as the resin layer (10) having excellent barrier properties are made of polyethylene terephthalate (PET), and the intermediate layer is made of sodium carbonate and citric acid as foaming agents. Foamed resin layer made by foaming polystyrene (PS) using a foaming agent (20)
Is injected by a multilayer injection molding machine, and PET,
A laminated cup was obtained as a wall (1) of a package made of foamed PS containing an intermediate layer containing carbon dioxide gas.

The thickness of the cup obtained above was 20 μm for both the outer layer and the inner layer, and was 50 μm to 90 μm for the intermediate layer.

Using the obtained cup, oil was added as a content, and carbon dioxide gas was filled during sealing to seal the lid material. The oil in this cup was less oxidatively degraded than the one in which the oil was filled in a cup having no foamed resin layer (20), and could be stored for a long time.

[0036]

As described above, the present invention has the following effects. That is, between or on one side of a resin layer having excellent barrier properties, a gas is bubbled, and a wall of a package formed by laminating one or more foamed resin layers filled with the gas, wherein the gas is argon , Helium, water vapor,
By using an inert gas such as nitrogen or carbon dioxide as a simple gas or a mixed gas of these gases, when the package is filled with contents, it is necessary to purge the package with an inert gas such as nitrogen or carbon dioxide from the outside. It is possible to provide an inexpensive package without oxygen permeation and no permeation of nitrogen, carbon dioxide, etc. from the inside, and it is possible to extend the expiration date of the contents such as food.

Further, by using the above-mentioned gas as a simple gas of a gas such as ethylene or methane which promotes the growth of plants or a mixed gas thereof, a package which can ripen fruits such as bananas more quickly. Can be provided.

Therefore, the present invention exerts an excellent practical effect in applications such as a wall of a package capable of extending the shelf life of fresh food or the like or a package capable of rapidly ripening fruits and the like. .

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a wall of a package according to an embodiment of the present invention in a side cross section.

FIG. 2 is an explanatory diagram showing a side wall of a wall of a package according to another embodiment of the present invention.

[Explanation of symbols]

 1 wall of package 10 resin layer with excellent barrier property 10a inner surface of resin layer with excellent barrier property 20 foam resin layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 27/32 B65D 81/24 A B65D 81/24 D C08J 9/04 CES C08J 9/04 CES B29C 67 / 22 // B29K 23:00 105: 04 B29L 9:00 (72) Inventor Masayoshi Suzuda 1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd. F-term (reference) 3E067 AA11 AB08 AB09 BA03A BB14A BB17A BB25A CA04 CA24 GA19 GD01 4F074 AA17 AA24 AA32 AA43 AA66 AA72 BA07 BA13 BA31 BA32. AA13 AA24 AA29 AB02 AB03 AG01 AG03 AH01 KA01 KA11 KB13 KB26 KF04 KJ06 KK04 4F212 AA04 AA11 AA13 AB02 AB16 AB19 AD05 AG03 AG20 AH54 U A01 UB13 UG05 UG07

Claims (4)

[Claims] 1. A wall of a package, comprising a foamed resin layer foamed with a gas layer laminated between or on resin layers having excellent barrier properties. 2. The wall of the package according to claim 1, wherein the gas is filled in the foamed resin layer. 3. The wall of a package according to claim 1, wherein the gas is a single gas of an inert gas such as argon, helium, water vapor, nitrogen or carbon dioxide, or a mixed gas thereof. body. 4. The wall of a package according to claim 1, wherein the gas is a single gas of a gas such as ethylene or methane that promotes plant growth or a mixed gas thereof.