JPH1170626A - Easy-open composite film for heat-resistant containers - Google Patents

Abstract

(57) [Problem] To provide an excellent heat sealing property not only for a general polyolefin resin but also for a high heat resistant resin such as a polycarbonate resin and a thermoplastic polyester resin.
Provided is an easy-opening composite film that has excellent sealing properties in a distribution process and can be suitably used as a lid material or a bottom material for a heat-resistant container that can be easily peeled off during use. SOLUTION: The heat seal layer is made of an amorphous polyester resin, the thickness of the layer is in the range of 2 to 10 μm, and the heat seal layer is peeled off at the interface between the heat seal layer and an adjacent layer at the time of peeling. Easy-opening composite film for heat-resistant containers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite film, and more particularly, to a heat-sealing property excellent in heat-resistant resin such as polycarbonate resin, thermoplastic polyester resin and the like, in particular, the sealing layer is not limited to ordinary polyolefin resin. The present invention relates to an easy-opening composite film which has excellent sealing properties in a distribution process and can be suitably used as a lid material or a bottom material for a heat-resistant container which can be easily peeled off at the time of use.

[0002]

2. Description of the Related Art In a gas pack package in which food is filled in a deep drawn package and filled with an inert gas such as nitrogen gas, a packaging material having both sealing properties and easy opening properties is required. Have been. Conventionally, since the ordinary polyolefin resin is used for the seal layer of the easily-openable composite film used for such an application, in a heat-resistant container for a microwave oven, the polycarbonate resin used as the constituent resin or There is a problem that it is difficult to maintain complete sealing with a high heat resistant resin such as a thermoplastic polyester resin.

[0003]

According to the present invention, an easy-opening composite film having both a sealing property and an easy-opening property capable of solving the above-mentioned problems has been found. The layer is made of an amorphous polyester resin, and the thickness of the layer is in the range of 2 to 10 μm,
An easily openable composite film for a heat-resistant container, wherein the film is peeled off at the interface between the heat seal layer and an adjacent layer at the time of peeling.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the present invention, the amorphous polyester provided in the heat seal layer is a copolymer composed of ethylene glycol, terephthalic acid and 1,4-cyclohexanedimethanol. Examples of the amorphous polyester include Eastman Chemical Company. PETG6763 (glass transition point: 81 ° C.) can be suitably used.

Here, the thickness of the heat seal layer is 2 to 10
If the thickness is less than 2 μm, the resin melted during heat sealing may be broken by the pressure of the seal and may not be completely sealed. If the thickness exceeds 10 μm, the seal layer will break at the end of the seal when peeled. However, the peeling between the layers proceeds to a portion other than the seal portion, and the fibrous or film-like seal layer remains on the peeled surface.

A layer adjacent to the heat seal layer made of the amorphous polyester resin is usually provided with a polyolefin adhesive resin, and the polyolefin adhesive resin is at least one selected from unsaturated carboxylic acids or derivatives thereof. An acid-modified polyolefin resin grafted with one kind of monomer can be suitably used, and is peeled off at the interface with the heat seal layer.

In the composite film of the present invention, in addition to the amorphous polyester layer and the adhesive resin layer adjacent thereto, a polyamide resin, a saponified ethylene vinyl acetate copolymer resin,
It is possible to co-extrude a polyolefin-based resin or the like. Dry lamination of a vinyl chloride film or the like is also possible.

[0008]

The present invention will be described below with reference to examples. Example 1 As a lid material, an amorphous polyester resin (PE)
TG) of 3 μm was obtained. Biaxially stretched polyester film layer (16μm thickness) //
Ethylene vinyl acetate copolymer saponified resin layer (thickness 10
μm) / polyamide resin layer (thickness 25 μm) / adhesive resin layer (thickness 15 μm) / PETG layer (thickness 3 μm)
m) Here, ~ is a composite film obtained by a co-extrusion molding method, and a 5-layer composite film for a cover material was obtained by dry laminating the outer layer side of the composite film.

Further, as a bottom material, a composite film having the following five layers of a polycarbonate resin having a sealing layer was obtained by a co-extrusion molding method. Polycarbonate resin layer (thickness 150μ)
m) / adhesive resin layer (thickness 15 μm) / saponified ethylene vinyl acetate copolymer resin layer (thickness 20 μm) / adhesive resin layer (thickness 15 μm) / polycarbonate resin layer (thickness 150 μm).

Example 2 A composite film for a lid and a bottom having the same structure as in Example 1 was obtained except that the thickness of the sealing layer PETG of the lid was changed to 10 μm.

Example 3 A cover film having the same structure and the same thickness as that of Example 1 was used, but the following five-layer composite film in which the sealing layer of the bottom material was a linear low-density polyethylene was obtained by a coextrusion molding method. . Polycarbonate resin layer (thickness 250 μm) / adhesive resin layer (thickness 1
5 μm) / a saponified ethylene vinyl acetate copolymer resin layer (thickness: 20 μm) / adhesive resin layer (thickness: 15 μm) / linear low-density polyethylene layer (thickness: 50 μm).

Example 4 As a cover material, the following five-layer composite film having a sealing layer made of linear low-density polyethylene was obtained. Biaxially stretched polyester film layer (16μm thickness) //
Ethylene vinyl acetate copolymer saponified resin layer (thickness 10
μm) / polyamide resin layer (thickness: 20 μm) / adhesive resin layer (thickness: 10 μm) / linear low-density polyethylene layer (thickness: 30 μm) where is a composite film obtained by a coextrusion molding method. By dry laminating the outer layer side, a five-layer composite film for a cover material was obtained.

As a bottom material, a composite film having the following five layers having a seal layer PETG of 5 μm was obtained. Polycarbonate resin film layer (thickness 300μm)
// Ethylene vinyl acetate copolymer saponified resin layer (thickness 1
0 μm) / polyamide resin layer (thickness 20 μm) / adhesive resin layer (thickness 15 μm) / PETG layer (thickness 5 μm)
m) Here, ~ is a composite film obtained by a co-extrusion molding method, and a five-layer composite film for a bottom material was obtained by dry laminating the outer layer side of the composite film.

Comparative Example 1 A composite film for a cover and a bottom having the same structure as in Example 1 except that the thickness of the sealing layer PETG of the cover was changed to 1 μm.

Comparative Example 2 A composite film for a cover and a bottom having the same structure as in Example 1 except that the thickness of the sealing layer PETG of the cover was changed to 12 μm.

Comparative Example 3 The bottom material had the same structure and the same thickness as in Example 1, but the sealing layer of the lid material was a linear low-density polyethylene, and the adjacent layer was polypropylene and ethylene-α-olefin copolymer. Was blended in an amount of 30% by weight to obtain a composite film having the following six layers.

Biaxially stretched polyester film layer (thickness 16 μm) // saponified ethylene vinyl acetate copolymer resin layer (thickness 10 μm) / polyamide resin layer (thickness 20 μm)
m) / Adhesive resin layer (thickness 10 μm) / Layer in which 30% by weight of ethylene-α-olefin copolymer is blended with polypropylene (thickness 20 μm) Here, is a composite film obtained by a co-extrusion molding method. By dry laminating the outer layer side, a 6-layer composite film for a cover material was obtained.

[Evaluation Test Method] A deep-drawing packaging machine (Multipack ()) was prepared using the composite films for lids and composites for bottom materials of Examples 1 to 4 and Comparative Examples 1 to 3 obtained as described above. 120mm length x 16 width by R-7000)
Create a sealed pack of 0mm x 25mm deep,
The peel appearance and peel strength (easy peel strength) when the lid material was peeled were evaluated.

(1) Appearance of peeling After peeling off the lid material, a good sealing portion of the lid material without leaving a film shape (（), a sealing portion of the lid material remaining on the bottom material side in a film shape of 3 mm or more. (X).

(2) Peeling Strength (Easy Peeling Strength) The peeling strength of the lid material was measured by a tensile test,
Those in the range of 000 gf / 15 mm width were rated as (○), and those outside the range were rated as (x).

[0021]

[Table 1]

[0022]

As described above, according to the composite film of the present invention, the seal layer is not limited to a normal polyolefin resin, but may be formed of other heat-resistant resins such as a polycarbonate resin and a thermoplastic polyester resin. It has excellent heat sealing properties, is excellent in sealing properties of packages in the distribution process, and can be suitably used as a lid material or a bottom material for heat-resistant containers that can be easily peeled off when opened.

Claims (1)

[Claims] The heat seal layer is made of an amorphous polyester resin, the thickness of the layer is in the range of 2 to 10 μm, and the heat seal layer is peeled off at the interface between the heat seal layer and an adjacent layer at the time of peeling. Easy-opening composite film for heat-resistant containers.