JP3033775B2 - Barrier container - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barrier container, and more particularly to a barrier container which satisfies gas barrier properties without using a metal thin film and has excellent container strength.

[Conventional technology]

Conventionally, containers made of plastic, paper, or a composite material of these materials that require gas barrier properties are:
2. Description of the Related Art It is a common practice to form a packaging material constituting a container into a laminate structure, and to further interpose an aluminum foil layer in the laminate. Such containers are typically single-use disposable containers.

However, waste disposal in recent years has been highlighted as a major social issue, and it has been proposed to collect and recycle plastic containers and paper containers. Container forms that can cope with this have been actively studied. It is getting.

That is, the paper part of the container is recycled as it is,
It is being studied to separate plastic and paper bonded together and recycle them.

[Problems to be solved by the invention]

However, as for the barrier container having the aluminum foil layer, a metal foil such as an aluminum foil laminated between plastic and paper cannot be easily separated. It has become difficult to actually carry out separation, separation and collection.

In view of such circumstances, an object of the present invention is to provide a container having excellent gas barrier properties without using a metal foil such as an aluminum foil and also having excellent container strength.

[Means for solving the problem]

In order to solve the above problems, the barrier container of the present invention is provided with a barrier layer containing an ethylene-vinyl alcohol copolymer resin on the outermost surface side of the container, and containing an adhesive polyolefin resin inside the barrier layer. Through the adhesive layer to
It was configured such that a packaging material base material having an olefin resin was laminated and provided on both sides of the paper.

[Action]

The container of the present invention is provided with a barrier layer containing an ethylene-vinyl alcohol copolymer resin on the outermost surface side of the container,
Since a base material for a wrapping material having an olefin resin is laminated on both sides of the paper via an adhesive layer containing an adhesive polyolefin resin inside the barrier layer, an aluminum foil or the like is provided as in the related art. It has gas barrier properties that can withstand practical use without using a metal foil, and has extremely excellent container strength.

〔Example〕

The configuration of the container of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view of a Goebel top type container as an embodiment of a barrier container, and FIG. 2 is a sectional view of a packaging material constituting the container.

As shown in FIG. 2, the container of the present invention has a barrier layer 2 containing an ethylene-vinyl alcohol copolymer resin on the outermost surface to which the external atmosphere of the container can directly contact. A packaging material substrate 4 is provided on the inner surface side of the barrier layer 2 via an adhesive layer 3 containing an adhesive polyolefin-based resin.

The ethylene-vinyl alcohol copolymer resin contained in the barrier layer 2 has an ethylene content of 40 to 60 mol%.
It is preferable to use the ethylene-vinyl alcohol-based copolymer resin. If this value is less than 40 mol%, the temperature required for heat sealing becomes high, which is not practical.
On the other hand, if it exceeds 60 mol%, the tendency of the flavor components to be adsorbed to the contents increases.

Further, the thickness of the barrier layer 2 containing the ethylene-vinyl alcohol copolymer resin is preferably in the range of 5 to 30 μm. When this value is less than 5 μm, it is difficult to obtain a uniform film, and wrinkles are apt to be formed during bonding.
Further, there is a disadvantage that sufficient gas barrier properties cannot be obtained. If this value exceeds 30 μm, the film becomes too stiff, resulting in inconvenience that the moldability of the film becomes poor.

Such a barrier layer 2 is bonded to a packaging material base 4 via an adhesive layer 3 containing an adhesive polyolefin-based resin as described above.

Examples of the adhesive polyolefin-based resin contained in the adhesive layer 3 include polyethylene, ethylene-α-olefin copolymer, polypropylene, polybutene, polyisobutylene such as polyisobutylene, and polybutadiene and polyisoprene such as polyisoprene. Olefins or copolymers thereof and carbonyls based on, for example, carboxylic acids, carboxylate salts, carboxylic anhydrides, carboxylic esters, carboxylic amides or imides, aldehydes, ketones, etc. A group alone or a cyano (—CN) group; a hydroxy group; an ether group; One or more ethylenically unsaturated monomers having a combination with a ring or the like and a copolymer, etc. Specifically, A. Ethylenically unsaturated carboxylic acids: acrylic acid, methacrylic acid, maleic acid, Fumaric acid,
Crotonic acid, itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, etc. B. ethylenically unsaturated carboxylic anhydride: maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride , Tetrahydrophthalic anhydride, etc. C. Ethylenically unsaturated esters: ethyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, mono or diethyl maleate,
Vinyl acetate, vinyl propionate, propyl γ-hydroxymethacrylate, ethyl β-hydroxyacrylate,
Glycidyl acrylate, glycidyl methacrylate,
β.N-ethylaminoethyl acrylate, etc. D. Ethylenically unsaturated amide or imide: acrylamide, methacrylamide, maleimide, etc. E. Ethylenically unsaturated aldehyde or ketone: Acrolein, methacrolein, vinyl methyl ketone, vinyl butyl ketone, etc. It is composed of a copolymer with an ethylenically unsaturated monomer.

Such an adhesive layer 3 has a thickness of 5 to 30 μm. If this value exceeds 30 μm, there arises a disadvantage that the cost is increased and the texture is deteriorated.
If it is less than this, there arises a problem that a sufficient adhesive strength cannot be obtained.

By interposing such an adhesive layer 3, the adhesive strength between the ethylene-vinyl alcohol copolymer and the base material for packaging material is improved, and the effect of satisfying the strength as a container is exhibited.

The base material 4 for packaging material laminated with the barrier layer 2 via the adhesive layer 3 has an olefin-based resin layer 43, 45 laminated on both surfaces of a support 40 as shown in FIG. 3
Formed as a layer stack. As the support 40, paper, a biaxially oriented polyester film, a biaxially oriented polypropylene, or the like is generally used. The support 40 is not limited to a single layer and may be a laminate. The thickness is about 10 to 500 μm. Olefin-based resin layer formed on both sides of support 40
43 and 45 are particularly preferably resin layers of polyethylene (PE). Each thickness is about 5 to 60 μm.

Hereinafter, the present invention will be described in more detail with reference to specific experimental examples of the present invention.

Packaging Material 1 (Invention) Acid-resistant paper having a basis weight of 400 g / m ² was used as a support, and a low-density polyethylene resin “Milason 16sp: Mitsui Petrochemical” was used as an olefin-based resin layer on both the front and back sides of the paper. Industrial Co., Ltd. "was formed by extrusion coating to a thickness of 20 μm. As a result, a packaging base material (hereinafter referred to as base material a) of a three-layer laminate was obtained.

Next, an adhesive polyolefin resin “Admer AT499: Mitsui Petrochemical Industry Co., Ltd.” is placed on one side 43 of the base material a.
And a barrier layer made of an ethylene-vinyl alcohol copolymer resin "ethylene component 48 mol% EVAL EP-G: Kuraray Co., Ltd."

Packaging Material 2 (Comparative) The packaging material 1 had a configuration in which the adhesive layer of the adhesive polyolefin resin of the packaging material 1 was excluded. Otherwise, the configuration was the same as that of the packaging material 1.

Packaging Material 3 (Comparative) The ethylene-vinyl alcohol copolymer resin of the configuration of the packaging material 1 was changed to a low density polyethylene resin. Otherwise, the configuration was the same as that of the packaging material 1.

After punching out such various sheet-shaped packaging materials into a predetermined size, a bottomed container sample was produced by a predetermined box-making process.

Using these samples, tests for gas barrier properties and container strength were performed.

As a result, the sample using the packaging material 1 has a barrier property comparable to that using the conventional aluminum foil,
The container strength was also extremely excellent.

On the other hand, although the sample using the packaging material 2 was excellent in barrier properties, the strength of the container was small, and when the container was dropped, the sealing portion was broken and the contents leaked.

Further, the sample using the packaging material 3 had low barrier properties and was not practical.

As for gas barrier properties, sample with bottomed container
After filling 1.0% with 100% orange juice and storing at 5 ° C. for 3 weeks, evaluation was made by the amount of residual vitamin C in the juice. Packaging materials 1 and 2 had a residual amount of 60% of the initial amount of vitamin C, but packaging material 3 had only 20% remaining.

The container strength was evaluated by dropping the bottomed container sample from a height of 50 cm and observing the state of liquid leakage.

〔The invention's effect〕

 The effects of the present invention are clear from the above results.

That is, in the container of the present invention, a barrier layer containing an ethylene-vinyl alcohol-based copolymer resin is provided on the outermost surface side of the container, and an adhesive layer containing an adhesive polyolefin-based resin is provided inside the barrier layer. Since the base material for wrapping material having an olefin resin on both sides is laminated and provided, even if a metal foil such as an aluminum foil is not used as in the related art, it has gas barrier properties that can withstand practical use, and has a strong container strength. Also have very good properties. Therefore, recycling use is also possible.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a Goebel top type container as an embodiment of a barrier container, and FIG. 2 is a cross-sectional view of a packaging material constituting the container. 2 ... barrier layer, 3 ... adhesive layer containing adhesive polyolefin resin, 4 ... base material for packaging material.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B65D 65/40

Claims (1)

(57) [Claims] 1. A barrier layer containing an ethylene-vinyl alcohol copolymer resin is provided on the outermost surface side of a container, and an adhesive layer containing an adhesive polyolefin resin is provided inside the barrier layer. A barrier container comprising a base material for packaging material having an olefin resin laminated on both sides of paper.