JPH0736746Y2 - Packaging material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a packaging material suitable for use in a sealed packaging bag for foods, pharmaceuticals and the like.

[Conventional technology]

A sealed plastic bag is often used for packaging raw confectioneries, jams, paste foods, sauces, and various other processed foods. These light packaging bags are often required to have sufficient oxygen resistance to prevent alteration of the contents, in addition to sufficient strength according to the contents so as not to be broken during handling. On the other hand, it is desirable that the light packaging bag can be easily torn by hand when it is opened, and if it is difficult to tear, not only uncomfortably strong force is required, but also the contents are spilled due to the shock caused by opening. To get dirty.

Conventionally adopted as a means for obtaining a packaging material which is easy to tear is a method of producing a bag by using a uniaxially stretched film of polyethylene or polypropylene and arranging the stretching direction in the tearing direction. Nevertheless, tearing is not easy when the thickness is about 30μ or more. In addition, these uniaxially stretched films are insufficient in heat resistance and strength to be used as a surface layer base material, and a sealant for enabling heat sealing can be heat sealable at a low temperature accordingly. It has to be used, or is often ruptured after being made into a package, and pinholes are leaked. Furthermore, since it is oxygen permeable, alteration during storage is inevitable depending on the content.

[Problems to be solved by the device]

Therefore, an object of the present invention is to provide a packaging material for a sealed bag which is excellent in strength and oxygen barrier property and is easy to tear and open.

[Means for Solving the Problems]

The packaging material successfully provided by the present invention has a thickness of 9 to
A uniaxially oriented rolled three-layer laminated film and a sealant layer are sequentially laminated on one surface of a base film made of a 20μ biaxially oriented film, and the uniaxially oriented rolled three-layer laminated film is made of an ethylene vinyl alcohol copolymer. And a surface layer made of polyethylene, polypropylene, polyamide, or polyethylene terephthalate, and has a total thickness of 15 to 30 μm.

A biaxially stretched film having physical properties suitable for bag making, such as polyethylene terephthalate, polypropylene and nylon, is used as the base material film of this packaging material. Its thickness is
About 9 to 20 μ is suitable.

The uniaxially oriented rolled three-layer laminated film adhered to the base film is a coextrusion laminated film which is uniaxially oriented by the rolling method described in JP-B-55-17694 and JP-B-63-51092. It is a film. Among them, in the present invention, the one in which the intermediate layer is an ethylene vinyl alcohol copolymer is used. The surface layer of the uniaxially oriented rolled three-layer laminated film is made of polyethylene, polypropylene, polyamide, polyethylene terephthalate, or the like. The uniaxially oriented rolled three-layer laminated film preferably has a total thickness of 15 to 30 μm.

As the sealant laminated on the surface of the uniaxially oriented rolled three-layer laminated film layer, a polyolefin resin is preferable,
Particularly preferred specific examples are low density polyethylene, ethylene vinyl acetate copolymer, polypropylene and the like. A suitable thickness is 15 to 60 μm.

One of the methods for producing the packaging material of the present invention from the above-mentioned materials constituting each layer is a method of simultaneously laminating three layers by using a so-called tandem extrusion laminating method. In this case, the base film layer is previously given an anchor coating agent,
Polyethylene or polypropylene is extrusion-laminated between the base film layer and the uniaxially oriented three-layer laminated film layer to form an adhesive layer. Another method is a method of adhering each layer constituent material by a so-called dry laminating method using an adhesive. Suitable adhesives used in this case are polyurethane-based ones.

[Action]

In the packaging material of the present invention, the uniaxially oriented rolled three-layer laminated film has the same molecular orientation as the uniaxially stretched film in the conventional tearable packaging material even when the base film is laminated. Makes it possible to tear.

A base film made of a biaxially stretched film not only supplements the strength lacking under severe usage conditions with a uniaxially oriented three-layer laminated film, but also tears the uniaxially oriented three-layer laminated film in the orientation direction. When done, it prevents tearing deformation of the three-layer laminate film, allowing for clean tearing. As long as the thickness of each layer is within the above specific range, the base film made of a biaxially stretched film does not make tearing difficult.

Further, the ethylene vinyl alcohol copolymer layer introduced into the packaging material of the present invention in the form of a uniaxially oriented rolled three-layer laminated film improves the oxygen barrier property of the packaging material and is a sealed bag with good storage stability of contents. Enables manufacturing.

The packaging material of the present invention has the same orientation as the case of producing a sealed bag using a conventional easily tearable film, and the orientation direction of the uniaxially oriented rolled three-layer laminated film layer is arranged in the tearing direction, and heat is applied by a conventional method. It can be easily sealed into a bag.

〔Example〕

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.
The test methods for physical properties are as follows.

 Tear strength According to JIS P8116.

Preservation of contents Each processed food is hermetically sealed in a bag made of packaging material.
After left in the room for 1 month, the state and taste of the contents were examined.

Compressive strength According to JIS Z0238, fill the four-sided seal package with water and
A load of g was applied and left for 1 minute. In addition, when there was no breakage, it was indicated as passing, and when it exploded, it was indicated as bursting.

 Puncture strength According to JAS 1019.

Example 1 As shown in the drawings, a biaxially stretched polyethylene terephthalate film (thickness 12 μm) was used as the base film 1, an isocyanate-based anchor coating agent was applied to one side thereof, and polyethylene immediately after melt extrusion was applied to the applied side. Using the thin film 2 (thickness: 15μ) as an adhesive, a uniaxially oriented rolled three-layer laminated film 3 (thickness: 20μ; layer structure: polyethylene 3a / ethylene vinyl alcohol copolymer 3b / polyethylene 3c) is bonded, and at the same time A sealant 4 (ethylene vinyl acetate copolymer; thickness 25 μ) was extruded on the surface of the axially-oriented rolled three-layer laminated film layer 3 and laminated to obtain a packaging material having a three-layer structure.

Example 2 A biaxially stretched nylon film (thickness 15
was used in the same manner as in Example 1 to obtain a packaging material having a three-layer structure.

Example 3 A biaxially stretched polypropylene film (thickness 20 μm) was used as a base film, and polypropylene (15 μm) immediately after melt extrusion was used as an adhesive on one surface of the film to form a uniaxially oriented rolled three-layer laminated film (thickness 20 μm; layer). Constitution: polypropylene / ethylene vinyl alcohol copolymer / polypropylene) is adhered, and at the same time, a sealant (polypropylene; thickness 20μ) is extruded and laminated on the surface of the uniaxially oriented rolled three-layer laminated film layer to form a three-layered package. I got the material.

Comparative Example 1 Example 1 except that a uniaxially oriented polyethylene film (thickness 20 μm) was used instead of the uniaxially oriented rolled three-layer laminated film.
A packaging material having a three-layer structure was obtained in the same manner as in.

Comparative Example 2 A biaxially stretched nylon film (thickness 15
μ), an ethylene vinyl alcohol copolymer film (thickness 20 μ) is adhered to one side of the film, and further,
Ethylene vinyl alcohol copolymer film (thickness 30
was used as a sealant layer to obtain a packaging material having a three-layer structure. The adhesion was performed by a dry laminating method using a urethane adhesive.

Comparative Example 3 A uniaxially stretched polypropylene film (thickness 20 μm) was used as a base film, and polypropylene resin was extruded on one side thereof so as to have a thickness of 20 μm and laminated to obtain a two-layer structure packaging material. .

Table 1 summarizes the physical properties of the packaging materials of the above examples.

[Effects of the Invention] As described above, a base film made of a biaxially stretched film having a thickness of 9 to 20 μm has a thickness of 15 to 30 μ on one side, and a uniaxially oriented rolling 3
The wrapping material of the present invention has a stable quality because the laminated film and the sealant layer are laminated in this order, and the uniaxially rolled three-layer laminated film has an ethylene vinyl alcohol copolymer layer as an intermediate layer. It has sufficient strength and oxygen barrier properties to produce a sealed bag for a product in which the property is important, and can be easily and cleanly torn by hand. Furthermore, since it can be easily manufactured by the tandem extrusion laminating method, it is extremely excellent as a packaging material for products requiring high quality stability.

[Brief description of drawings]

 The drawings are sectional views showing an embodiment of the present invention. 1: Base film, 2: Adhesive layer 3: 1-axis oriented rolled 3-layer laminated film 3a: Ethylene vinyl alcohol copolymer layer 4: Sealant layer

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Claims (1)

[Scope of utility model registration request] 1. A uniaxially oriented rolled three-layer laminated film and a sealant layer are sequentially laminated on one side of a base film made of a biaxially stretched film having a thickness of 9 to 20 μm. A packaging material, wherein the film has an intermediate layer made of an ethylene vinyl alcohol copolymer and a surface layer made of polyethylene, polypropylene, polyamide, or polyethylene terephthalate, and has a total thickness of 15 to 30 μm.