JP2730164B2 - Easy peeling laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an easily peelable laminated film which is usually an integrated laminate and can be easily peeled off under a certain use condition. Particularly, the present invention relates to an easily peelable film suitable as a double wrapping film which does not normally show air permeability but can impart good air permeability as required.

(Prior Art) Conventionally, a so-called perforated film in which a plurality of through holes are provided in a single synthetic resin film such as a polyethylene film or a polypropylene film for the purpose of imparting air permeability, is widely used as a packaging film for fruits and vegetables. It is used. A laminated film obtained by heat-sealing the above-mentioned perforated film to paper (kraft paper, rayon paper, Japanese paper, etc.) or nonwoven fabric and bonding the same is used for packaging Japanese confectionery, desiccant, insect repellent, oxygen absorber, chemical warmer, etc. It is used as a film.

(Problems to be Solved by the Invention) However, it is impossible to impart moisture-proof properties and gas barrier properties to not only the above-mentioned perforated film having a through-hole but also the above-mentioned laminated film. Therefore, regarding the packaging of contents that dislike moisture and oxygen before use, once the individual contents are once wrapped with a perforated film, these packages are individually (individually wrapped) or a plurality of each (collective wrapping). ), Furthermore, it is necessary to package with an outer film having a moisture-proof property and a gas barrier property. However, in such a packaging form, there is a problem that the packaging is troublesome. If the package is not completely sealed again with the outer film in order to store the package, the various effects of the package are likely to be lost, and there is a problem that the storage is troublesome. In addition, it cannot be used for packaging contents that contain moisture and ooze out.

(Means for Solving the Problems) In the present invention, a perforated film having a through hole and a film not having a through hole are laminated, and an easily peelable laminated film having a specific range of adhesive strength between both films has been found. The above problem can be solved by using this laminated film to form a double wrapping film. The gist of the present invention is to provide a perforated synthetic resin film 1 having a plurality of through holes 3. And the synthetic resin film 2 having no through hole,
At least one facing film surface is subjected to corona discharge treatment and then laminated, and the adhesive strength at the interface 4 between the film 1 and the film 2 is set to be more than 100 g / 20 mm width and not more than 250 g / 20 mm width. It is in the easily peelable laminated film.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a schematic partial cross-sectional view showing an example of the laminated film of the present invention.

The film according to the present invention includes a very thin film to a thick sheet.

The symbol 1 in the figure is a perforated synthetic resin film, and various synthetic resins can be used as the synthetic resin film. In particular, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, etc. A polyolefin resin film having excellent adhesion can be suitably used.

The thickness range of the perforated film 1 is not particularly limited, but is preferably in the range of 5 μm to 200 μm, preferably 15 μm to 100 μm. If it is less than 5 μm, it is easily broken, and if it exceeds 200 μm, it lacks flexibility and is difficult to handle. .

The plurality of through holes 3 provided in the film 1 may each have a diameter of about 0.1 to 2 mm and an interval between the holes of about 0.5 to 10 mm, and can be easily provided by piercing a heating needle.

The symbol 2 in the figure is a synthetic resin film having no through-hole, and the resin to be used is not limited, but is made of polyvinyl chloride resin, polyolefin resin, nylon resin, polyester resin, polycarbonate resin, or the like. A single film can be used. In particular, when moisture resistance and gas barrier properties are required, saponified ethylene-vinyl acetate copolymer, polyvinylidene chloride, cellophane,
A composite film having a layer structure of a barrier material such as a metal foil may be used.

The thickness range of the film 2 is not particularly limited.
The range of μm to 300 μm, preferably 30 μm to 100 μm is good, and if it is less than 5 μm, the rigidity is inferior, and if it exceeds 300 μm, the flexibility is inferior and the film is difficult to peel off.

In the laminated film of the present invention, it is necessary that the above-mentioned perforated film 1 and the film 2 face each other and at least one of the facing film surfaces is subjected to corona discharge treatment before lamination.

As a method of the corona discharge treatment, a normal corona discharge treatment device having a high-frequency oscillator and an electrode and capable of continuous treatment (processing by passing a sheet between the corona discharge electrode and the counter electrode) may be used.

In the corona discharge treatment, the bonding strength of the interface 4 between the laminated film 1 and the film 2 by pressure lamination exceeds 100 g / 20 mm width.
Processing conditions such as corona discharge output and processing speed are appropriately adjusted so that the width becomes 50 g / 20 mm. The bonding strength of the interface 4 is 10
Below 0 g / 20 mm width, after lamination, when packaging foods containing moisture or alcohol content, it is easy to cause a problem of natural peeling during distribution and storage, and if it exceeds 250 g / 20 mm width,
There is a problem that it is extremely difficult to peel off the film, and it is difficult to exhibit the function as a double-wrapped film.

The above adhesive strength is a value measured at a take-off speed of 200 mm / min and a 180 ° peel test.

When the film is laminated by a method other than the corona discharge treatment of the present invention, for example, by a dry lamination method or an extrusion lamination method, the following problems occur.

(1) It is necessary to apply an anchor coating agent or an adhesive to the surface of the perforated film when bonding, and these are seen through from the through holes, and the film cannot be unwound in the case of a roll.

(2) An anchor coat agent, an adhesive or the like closes the through-hole, and the original air permeability is hindered.

(3) It is difficult to make the adhesive strength in an appropriate range.

 Hereinafter, the present invention will be described with reference to examples.

(Examples) Example 1 (1) Perforated film 1: stretched polypropylene film (thickness: 60 μm, hole diameter: 0.1 mm, hole interval: 1.5 mm) Film 2: co-extruded multilayer sheet having the following structure (thickness: 90 μm)
m) (Ethylene vinyl acetate copolymer * / acid-modified polyolefin resin / saponified ethylene vinyl acetate copolymer / nylon resin / acid-modified polyolefin resin / ethylene vinyl acetate copolymer) (2) Use the above films 1 and 2 Then, the perforated film surface and the surface of the ethylene-vinyl acetate copolymer * were subjected to a corona treatment under the following conditions, followed by thermocompression bonding.

Conditions of corona discharge treatment Corona discharge treatment machine (manufactured by VETAPHONE) High-frequency oscillator High-frequency output display Film 1 ... 2.4KW Film 2 ... 2.6KW Conditions for thermocompression bonding Films 1 and 2 are continuously corona-treated under the above conditions. Immediately, thermocompression bonding was performed under the following conditions.

Surface temperature of the thermocompression roll: 145 ° C. Roll contact pressure: 10 kg / cm Thermocompression speed: 15 m / min (3) The laminated film 1 obtained under the above conditions
The interfacial adhesion rate between the two was 110 g / 20 mm width. When this laminated film was used as a lid material for a container having a saponified product of polypropylene-ethylene-vinyl acetate copolymer as an intermediate layer, and the container was filled with instant curry, it showed good barrier properties during storage. Was. The film 2 could be easily peeled off during heating and cooking, and showed good air permeability after peeling.

Example 2 Corona discharge treatment was continuously performed under the same conditions as in Example 1, and thermocompression bonding was immediately performed under the following conditions.

Surface temperature of thermo-compression roll: 160 ° C Roll contact pressure: 10 kg / cm Thermo-compression speed: 15 m / min The interfacial adhesion speed between films 1 and 2 of the film obtained under the above conditions is 180 g / 20 mm width. there were. When this laminated film was used as a lid material for a container in the same manner as in Example 1, good barrier properties were exhibited, the film 2 was easily peeled off, and good air permeability was shown after peeling.

Comparative Example Corona discharge treatment was continuously performed under the same conditions as in the example, and thermocompression bonding was immediately performed under the following conditions.

Surface temperature of thermocompression rolls: 145 ° C Roll contact pressure: 10 kg / cm Thermocompression speed: 15 m / min Films 1 and 2 of the laminated films obtained under the above conditions
The interfacial bond strength between them was 80 g / 20 mm width.

When this laminated film was used as a lid material for a container in the same manner as in Example 1, the appearance was good immediately after packaging, but during storage, the film was partially spontaneously peeled off between the films 1 and 2, and the appearance deteriorated. However, it was inconvenient as a double-wrapped film.

(Effects of the Invention) As described above, the laminated film of the present invention can be used as a perforated film having air permeability by peeling it off, if necessary. Therefore, it is possible to simplify packaging of food and the like containing water and alcohol as a double wrapping film, and if it is used as a lid material of a microwave oven packaging container, by using only a perforated film at the time of heating, it is possible to prevent spilling over. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic partial sectional view showing an example of the laminated film according to the present invention. 1 ... perforated synthetic resin film 2 ... synthetic resin film 3 ... through-hole 4 ... interface

Claims (1)

(57) [Claims] 1. A perforated synthetic resin film (1) having a plurality of through-holes (3) and a synthetic resin film (2) having no through-holes face each other, and at least one facing film surface is corona-discharged. After the treatment, the laminate is laminated, and the adhesive strength at the interface (4) between the film (1) and the film (2) is set to be more than 100 g / 20 mm width and not more than 250 g / 20 mm width. Film.