JPH02274529A - Easily releasable laminate film - Google Patents

Abstract

PURPOSE:To enable a laminate film to be used as a gas-permeable porous film through a releasing operation, as required, by setting the adhesive strength at the boundary between a porous synthetic resin film and a synthetic resin film having no through-holes to a value of more than 100g/20mm and not more than 250g/20mm. CONSTITUTION:A porous synthetic resin film having a plurality of through-holes 3 and a synthetic resin film 2 having no through-holes are faced to each other. The surface of at least one of the faced films is treated by corona discharge, and the films are laminated with each other. The adhesive strength at the interface between the film 1 and the film 2 is set to a value of more than 100g/20mm and not more than 250g/20mm.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an easily peelable laminate film that is usually an integrated laminate and can be easily peeled off under certain conditions of use. In particular, the present invention relates to an easily peelable film suitable as a double wrapping film that normally does not exhibit air permeability, but can provide good air permeability when necessary.

(Prior art) So-called perforated films, in which multiple through holes are formed in a single synthetic resin film such as polyethylene film or polypropylene film, have been widely used as packaging films for fruits and vegetables for the purpose of imparting breathability. It is used. In addition, laminated films made by heat-sealing the above-mentioned perforated film with paper (kraft paper, rayon paper, Japanese paper, etc.), nonwoven fabric, etc. can be used to package Japanese sweets, desiccants, insect repellents, oxygen absorbers, chemical body warmers, etc. It is used as a film for

(Problems to be Solved by the Present Invention) However, it is impossible to impart moisture-proofing properties and gas barrier properties not only to the above-mentioned perforated film having through holes, but also to the above-mentioned laminated film. . Therefore, when it comes to packaging contents that are sensitive to moisture and oxygen before use, the individual contents are once packaged with a perforated film, and then the packages are packaged individually (individually packaged) or in multiple pieces ( In addition, it is necessary to package with an exterior film that has moisture-proof and gas barrier properties, but this type of packaging has the problem of being time-consuming. In order to store unused individual packages, there is a problem that unless they are completely sealed again with an exterior film, the packaged items tend to lose their various effects and storage is troublesome. Furthermore, it could not be used to package contents that contained moisture and would seep outside.

(Means for Solving the Problems) The present invention has discovered an easily peelable laminated film in which a perforated film having through holes and a film without through holes are laminated, and the adhesive strength between the two films is within a specific range. If this laminated film is used to make a double packaging film, the above problems can be solved, and the gist is: A perforated synthetic resin film with a plurality of through holes 3 and a synthetic resin film without through-holes are placed facing each other, and at least one of the opposing film surfaces is laminated after corona discharge treatment. .

The present invention will be explained below with reference to the drawings. FIG. 1 is a partially cross-sectional schematic diagram showing an example of the laminated film of the present invention.

The film referred to in the present invention includes an extremely thin film to a thick sheet. The symbol / in the figure indicates a perforated synthetic resin film, and the synthetic resin used for the film is as follows: Various materials can be used, especially polyethylene, polypropylene, ethylene-
A polyolefin resin film with excellent thermal adhesiveness such as a vinyl acetate copolymer or an ionomer resin can be suitably used. The thickness range of the apertured film l is not particularly limited, but Spm-λθopm, preferably 15 μm to 100 μm.
The range of m is good; less than 5 μm is easy to tear, and 200 μm is less than 5 μm.
If the diameter exceeds 0.0 m, there is a problem that the film lacks flexibility and is difficult to handle. /=about 2tran, the distance between the holes is O, S ~ l0
It can be easily provided by piercing with a heating needle.

Further, symbol 2 in the figure is a synthetic resin film that does not have through holes, and the resins used are not limited, but include polyvinyl chloride resin, polyolefin resin, nylon resin,
A single film made of polyester resin, polycarbonate resin, etc. can be used. In particular, when moisture resistance or gas barrier properties are required, a composite film having a layered structure of barrier materials such as saponified ethylene-vinyl acetate copolymer, polyvinylidene chloride, cellophane, metal foil, etc. may be used.

The thickness range of the above filmco is not particularly limited, but is 5μ
m~300 pm, preferably 30 pm~/0
A range of 0 pm is good, less than 5 μm is poor in rigidity, and 3
If it exceeds 0.00 pm, there is a problem that the flexibility is poor) and the film is difficult to peel off.

In the laminated film of the present invention, the above-mentioned perforated film/
and films 2 facing each other, and at least one facing film surface must be subjected to a corona discharge treatment before lamination.

The corona discharge treatment method has a high frequency oscillator and an electrode,
An ordinary corona discharge treatment device capable of continuous treatment (processing by passing a sheet between a corona discharge electrode and a counter electrode) may be used.

The corona discharge treatment improves the adhesive strength of the interface between the perforated film and the Film Co.
Processing conditions such as corona discharge output and processing speed are adjusted as appropriate so that the width exceeds the tm width and the width is between 2 and 02720.

If the adhesive strength of the above-mentioned interface is less than / 00 t 720 mm width, after lamination, when food containing moisture or alcohol is packaged, the problem of spontaneous peeling during distribution and storage is likely to occur.1.2.5θ ? /2 If the width exceeds the original width, there is a problem in that it is extremely difficult to peel the film (it is difficult to perform its function as a double wrapping film).

The above adhesive strength is determined by the value measured by the IGO'' peel test at a take-up speed of λθθ/min.

Note that if the films are laminated by a method other than the corona discharge treatment of the present invention, such as a dry lamination method or an extrusion lamination method, the following problems will occur.

(1) When adhering, it is necessary to apply an anchor coat agent or adhesive to the perforated film surface, and these materials show through the through holes, making it impossible to unwind the film.

(2) Anchor coating agents, adhesives, etc. block the through holes, impeding the original air permeability.

(3) Difficulty adjusting adhesive strength to an appropriate range0 Hereinafter, the present invention will be explained by examples.

(Example) Example / (1) Perforated film /; Stretched polypropylene film (thickness AOpm, pore diameter o, iyrm, hole spacing 8S, hole spacing 8S; coextruded multilayer sheet with the following configuration (thickness qop
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) Using the above film/, 2 Then, the perforated film surface and the ethylene-vinyl acetate copolymer main surface are heated. Conditions: The film was subjected to continuous corona discharge treatment under the above conditions, and immediately subjected to thermocompression bonding under the following conditions. Surface temperature of thermocompression roll.../lIN'C roll contact pressure...・10Kq/cm thermocompression bonding speed...
... / s rn 7 minutes (3) Interfacial adhesion speed between the film and the laminated film obtained under the above conditions: 110
It was 97,208 wide. In addition, this laminated film was used as a lid material for a container having a saponified polyglobylene-etherene-vinyl acetate copolymer as an intermediate layer and 1-, and the container was filled with instant curry. It showed good barrier properties. During cooking, the film λ could be easily peeled off, and after peeling off, the film showed good air permeability.

Example 2 A corona discharge treatment was carried out continuously under the same conditions as in Example 2, and immediately thermocompression bonding was carried out under the following conditions.

Surface temperature of thermocompression roll.../1,0'(:.

o -# Contact pressure.../θKg/an Heat compression bonding speed...-tstn 1 minute The interfacial adhesion strength between the film and the film obtained under the above conditions is between /gOV/2θ It was the width. When this laminated film was used as a cover material for a container in the same manner as in Example, it exhibited good barrier properties, the film could be easily peeled off, and good air permeability was exhibited after peeling.

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

Surface temperature of thermocompression roll...//I5℃ Roll contact pressure.../θKg/cmThermocompression bonding speed...
・The interfacial adhesion strength between film/ and 2 in the laminated film obtained under the above conditions at 15 m/min is KO? 7.20-width.

When this laminated film was used as a lid material for a container in the same manner as in Example 1, it had a good appearance after being used in other equipment, but during storage, natural peeling occurred partially between the film and - and the appearance deteriorated. However, this was inconvenient as a double wrapping 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, the double packaging film can simplify the packaging of foods containing moisture and alcohol, and when used as a lid for microwave heating packaging containers, only the perforated film is used during heating to prevent boiling over. can do 0

[Brief explanation of drawings]

FIG. 1 is a partially cross-sectional schematic diagram showing an example of a laminated film according to the present invention. l...Perforated synthetic resin film coat...
Synthetic resin film 3...Through hole...Interface

Claims (1)

[Claims] Perforated synthetic resin film having multiple through holes (3) (
1) and a synthetic resin film (2) having no through holes are placed facing each other, and at least one of the opposing film surfaces is subjected to corona discharge treatment, and then laminated, and the above film (1) is laminated.
The adhesive strength of the interface (4) between and the film (2) is 100g.
An easily peelable laminated film having a width exceeding /20 mm and not more than 250 g/20 mm width.