JPH11227140A - Composite film for gas pack packaging - Google Patents

Abstract

(57) [Problem] To provide a composite film having excellent waist hardness and transparency, which can be suitably used for gas pack packaging. SOLUTION: In a composite film formed by laminating a polycarbonate resin layer, a thermoplastic polyester resin layer, a gas barrier resin layer, and a polyolefin resin layer for sealing, the thermoplastic polyester resin layer has a thickness of 1
A composite film for gas pack packaging, wherein the thickness is in the range of 50 to 200 μm and the thickness of the polycarbonate resin layer is in the range of 10 to 30% of the thickness of the thermoplastic polyester resin layer.

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 composite film which is excellent in waist hardness and transparency and is suitable for gas pack packaging.

[0002]

2. Description of the Related Art Conventionally, as a composite film for gas pack packaging used as a bottom material obtained by deep drawing, a composite film having a structure in which a thermoplastic polyester resin layer or a polystyrene resin layer is disposed as an outermost layer. Are known. In the composite film having such a configuration, the thickness of the outermost thermoplastic polyester resin layer or the polystyrene resin layer is increased in order to impart rigidity to the bottom material.

[0003]

However, in the above configuration, the total thickness of the entire composite film must be 300 μm or more in order to satisfy the required waist hardness. Therefore, the total thickness tends to be reduced. However, reducing the total thickness inevitably causes the outermost layer to become thinner and weaker, resulting in poor rigidity of the bottom material. It was necessary to take measures such as providing ribs on the parts.

[0004] Accordingly, the present invention has been made to find a composite film having a layer structure capable of solving the conventional disadvantages, and an object of the present invention is to provide a composite film having both rigidity and transparency.

[0005]

The gist of the present invention is to provide a composite film in which a polycarbonate resin layer, a thermoplastic polyester resin layer, a gas barrier resin layer, and a polyolefin resin layer for sealing are laminated. The thickness of the thermoplastic polyester resin layer is 150 to
The thickness of the polycarbonate resin layer is in the range of 200 μm and the thickness of the thermoplastic polyester resin layer is 10 to 10 μm.
The composite film for gas pack packaging is characterized by being in the range of 30%.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the composite film of the present invention,
The reason why the thermoplastic polyester layer and the polycarbonate layer are laminated is that, even when the total thickness is reduced, the rigidity is strong and it is effective to give a rigid feeling. The polycarbonate resin having a molecular weight of 20,000 to 32,000 can be suitably used. As the thermoplastic polyester, a homopolymer obtained by polymerizing terephthalic acid and ethylene glycol or terephthalic acid and ethylene glycol and 1,
A copolymer obtained by copolymerizing 4-cyclohexanedimethanol is preferred, and the thickness of the thermoplastic polyester layer is 15
It is necessary to be in the range of 0 to 200 μm, and if it is less than 150 μm, the rigidity is weak and the rigid feeling is insufficient, and if it exceeds 200 μm, there is a problem in terms of cost.

Further, the thickness of the polycarbonate resin layer must be in the range of 10 to 30% of the thickness of the thermoplastic polyester resin layer. If the thickness is less than 10%, the rigidity is weak and the rigid feeling is inferior. When the composite sheet is brought into contact with a heating hot plate and heated, the surface of the composite sheet is formed on the hot plate, resulting in a rough surface, which impairs transparency.

The intermediate layer is mainly a gas-barrier resin layer, and is composed of a polyamide resin or a saponified ethylene-vinyl acetate copolymer resin or a laminate of a polyamide resin and a saponified ethylene-vinyl acetate copolymer resin.
As the polyamide resin, nylon 6, nylon 66,
Nylon 6/66, nylon 6T, nylon 6I, nylon 6T / 6I, nylon 12, meta-xylene adipamide, and the like can be suitably used, and the above-mentioned blends may be used.
Further, the polyamide resin layer may be provided separately in two layers.

As the saponified ethylene-vinyl acetate copolymer resin, those having an ethylene content of 30 to 60 mol% and a saponification degree of 95% or more are preferred from the viewpoint of gas barrier properties. For the innermost sealing resin layer, an ionomer resin, a copolymer of polyethylene or ethylene and other components, such as an ethylene-vinyl acetate copolymer, can be used,
The thickness of the layer can be suitably used in the range of 20 to 100 μm.

A polyolefin-based adhesive resin layer may be provided between the intermediate layer and the innermost layer, and between the thermoplastic polyester / polycarbonate laminate and the intermediate layer of the outer layer. An acid-modified polyolefin resin grafted with at least one monomer selected from saturated carboxylic acids or derivatives thereof can be suitably used. The thickness of the layer can be suitably used in the range of 5 to 20 μm.

In the present invention, the resin layer having the above constitution can be laminated by a usual dry lamination method or a co-extrusion method. Hereinafter, the present invention will be described with reference to examples.

[0012]

(Example 1) Layer configuration; Outermost layer (first layer): polyethylene terephthalate resin (PET), (second layer): polycarbonate resin (PC), (third layer): carboxylic acid-modified LLDPE
(AD), (fourth layer): saponified ethylene vinyl acetate copolymer (EVOH), (fifth layer): carboxylic acid-modified LL
DPE, (6th layer): Low density polyethylene (LDPE)
Arranged with.

PET / PC / AD / EVOH / AD / LDPE μm (150/45/10/10/10/30) The composite film having the above structure was formed by a co-extrusion method. This composite film is placed on a deep drawing packaging machine (R-7000) manufactured by Multibag Inc. so that the first layer is on the outside.
It was drawn to a size of 0 mm x 110 mm and a depth of 25 mm. The molding temperature is 100 ° C. As a result, the moldability and the transparency were good, and particularly, the rigidity of the waist at the corners was good and the rigidity was excellent.

(Example 2) Layer structure; outermost layer (first layer): polycarbonate resin (PC), (second layer): polyethylene terephthalate resin (PET), (third layer): ethylene-vinyl acetate copolymer Saponified product (EVOH), (fourth layer): nylon 6 (N
Y), (fifth layer): saponified carboxylic acid-modified ethylene-vinyl acetate copolymer (AD), (sixth layer): low-density polyethylene (LDPE).

Thickness: PC / PET // EVOH / NY / AD / LDPE μm (30/200 // 10/10/30/30) The composite film having the above structure was formed by a dry lamination method. Subsequently, when drawing was performed in the same manner as in Example 1, both the formability and the transparency were good, and the hardness of the waist at the corner was also
It was good.

(Comparative Example 1) Layer structure; outermost layer (first layer): polyethylene terephthalate resin (PET), (second layer): carboxylic acid-modified LL
DPE (AD), (third layer): saponified ethylene vinyl acetate copolymer (EVOH), (fourth layer): carboxylic acid-modified LLDPE (AD), (fifth layer): low density polyethylene (LDPE) Arranged configuration.

PET / AD / EVOH / AD / LDPE μm (300/10/10/10/30) The composite film having the above structure was formed by a co-extrusion method. Then, when drawing was performed in the same manner as in Example 1, moldability and
The transparency was good and the waist hardness at the corner was good, but there was a problem in cost.

(Comparative Example 2) Layer structure; same as Comparative Example 1 Thickness: PET / AD / EVOH / AD / LDPE μm (200/10/10/10/30) The composite film having the above structure was produced by a coextrusion method. Filmed. Then, when drawing was performed in the same manner as in Example 1, moldability and
Transparency was good, but the corners were weak,
It was easy to deform without ribs.

(Comparative Example 3) Layer structure: outermost layer (first layer): polycarbonate resin (PC), (second layer): carboxylic acid-modified LLDPE (A
D), (third layer): saponified ethylene vinyl acetate copolymer (EVOH), (fourth layer): carboxylic acid-modified LLDP
E (AD), (5th layer): Low density polyethylene (LDP)
E) Arranged configuration.

Thickness: PC / AD / EVOH / AD / LDPE μm (200/10/10/10/30) The composite film having the above structure was formed by a co-extrusion method. Subsequently, when drawing was performed in the same manner as in Example 1, molding could not be performed at a molding temperature of 100 ° C. On the other hand, although molding was possible at 150 ° C. or higher, when the innermost layer PE came into contact with the hot plate for molding heating, the surface was removed and the surface was roughened.

[0021]

As described above, according to the composite film for gas pack packaging of the present invention, the rigidity of the waist and the transparency are excellent, and it can be suitably used for gas pack packaging.

Claims (1)

[Claims] 1. A composite film comprising a polycarbonate resin layer, a thermoplastic polyester resin layer, a gas barrier resin layer, and a polyolefin resin layer for sealing, wherein the thermoplastic polyester resin layer has a thickness of 1
A composite film for gas pack packaging, wherein the thickness is in the range of 50 to 200 μm and the thickness of the polycarbonate resin layer is in the range of 10 to 30% of the thickness of the thermoplastic polyester resin layer.