JP2920458B2 - Coextrusion composite film for deep drawing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a co-extruded composite film, and more particularly to a co-extruded composite film for deep drawing capable of being sterilized in boil and having excellent gloss, transparency, label adhesion, pinhole resistance and the like.

[0002]

2. Description of the Related Art After filling a package such as ham into a deep-drawn bottom material, sealing the lid, and then sterilizing the boil with hot water, such deep-drawing for boil sterilization is performed. As a film for a bottom material, a dry laminate product composed of a non-stretched polyamide resin layer / sealable resin layer, a non-stretched polypropylene resin layer / a non-stretched polyamide resin layer (K-coated polyamide resin layer) / sealable resin layer, and the like is frequently used. However, there is a problem that the pinhole resistance after molding is inferior and that curling easily occurs. In addition, those in which an unstretched polypropylene resin layer is dry-laminated on the outermost layer of a co-extruded product having various layer configurations are also used,
When a label is applied to the surface of a molded product, there are problems such as easy peeling of the label and poor label adhesion.

[0003]

SUMMARY OF THE INVENTION The present invention has found a co-extruded composite film which can solve the above-mentioned problems. The gist of the present invention is that the outermost layer is a 12 nylon resin layer,
Or a copolymerized polyamide resin layer of 12 nylon and 6 nylon, a polyamide resin layer with an intermediate layer sandwiched between polyolefin adhesive resin layers, or an ethylene-vinyl acetate copolymer with a polyamide resin layer sandwiched between polyolefin adhesive resin layers. A co-extruded composite film for deep drawing wherein the combined saponified layer and the innermost layer are provided with a sealing resin layer, and the outermost layer has a thickness of 15% or less of the total thickness.

In the coextruded composite film of the present invention, 12
Nylon resin (hereinafter referred to as "12PA") layer or 1
The reason why the polyamide resin of 2 nylon and 6 nylon (hereinafter referred to as “12-6PA”) layer was disposed as the outermost layer was
Because it is effective in preventing whitening of films and blocking between packages (wet heat blocking) in boil sterilization treatment, it can give gloss and transparency to films, and is effective in improving label adhesion. It is.

The thickness of the 12PA layer or 12-6PA layer must be 15% or less of the total thickness of the composite film, and if it exceeds 15%, the pinhole resistance is poor.
Another problem is that the film is easily curled. A specific thickness in the range of 5 to 30 μm can be suitably used. Further, the thickness of the above-mentioned 12PA layer or 12-6PA layer is preferably not more than 15% of the total thickness of the composite film and not more than half of the thickness of the intermediate layer,
If the thickness exceeds half the thickness of the intermediate layer, the moldability during deep drawing tends to be poor.

For the innermost sealing resin layer, an ionomer resin, polyethylene, or a copolymer of ethylene and other components, for example, an ethylene-vinyl acetate copolymer, can be used. It is preferable to use an ionomer resin which can improve the transparency of the resin. The thickness of the sealing resin layer can be suitably used in the range of 30 to 150 μm.

The intermediate layer is a barrier resin layer and is composed of a polyamide resin layer or a polyamide resin layer and a saponified ethylene vinyl acetate copolymer (hereinafter referred to as "EVOH") layer. As polyamide resin, nylon 6,
Nylon 66, Nylon 6/66, Nylon 6T / 6I
And the like, and 12PA or 1 which is the same as the outermost layer
2-6PA may be used. EVOH having an ethylene content of 30 to 60 mol% and a saponification degree of 95% or more is preferable from the viewpoint of moldability and barrier properties.

The thickness of the intermediate layer may be in the range of 10 to 100 μm when only the polyamide resin layer is used. In the case of the polyamide layer and the EVOH layer, the thickness of the polyamide resin layer is 10 to 70 μm and the thickness of the EVOH layer is 100 μm
Should be within the range.

It is necessary to provide a polyolefin-based adhesive resin layer between the outermost layer and the intermediate layer and between the innermost layer and the intermediate layer. As the polyolefin-based adhesive resin to be used, an unsaturated carboxylic acid or a derivative thereof is used. Modified polyolefin resin grafted with at least one monomer selected from the group consisting of 12PA layer or 12-6
The PA layer, the intermediate layer, and the sealing resin layer can be firmly bonded to each other. Further, the pinhole resistance of the entire film can be improved by disposing a polyolefin-based adhesive resin layer having excellent pinhole resistance on both sides of the barrier resin layer in which pinholes are easily generated. The thickness of each polyolefin-based adhesive resin layer may be in the range of 5 to 20 μm.

In the present invention, since the resin layer having the above structure is laminated by a co-extrusion method, transparency, gloss, deep drawing formability and pinhole resistance are good, and the wet heat treatment at the time of boil sterilization at 90 ° C. or more is performed. Blocking, film whitening,
A composite film free from curling or the like and having excellent physical properties and appearance can be obtained.

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

[0012]

【Example】

Example 1 Layer structure: outermost layer (first layer): 12 PA layer, second layer: carboxylic acid-modified ethylene-vinyl acetate copolymer (AD), third layer: nylon 6, fourth layer: EVOH, fifth layer Layer: carboxylic acid-modified ethylene-vinyl acetate copolymer (AD), No. 6
Layer: a configuration in which an ethylene-vinyl acetate copolymer (EVA) is provided.

Thickness: 12 PA / AD / Nylon-6 / EVOH / AD / EVA (10 μm / 15 μm / 60 μm / 10 μm / 10 μm / 95 μm) Ratio of thickness of outermost layer to total thickness = 5% Coextruding composite film having the above configuration. A film was formed by a molding method. Then, put the composite film so that the first layer is on the outside.
Deep drawing packaging machine (R-7000) manufactured by Mulchivac Co., Ltd.
And drawn. The shaped hole was filled with amorphous ham, covered with a lid material (a dry laminate film composed of stretched polypropylene / K-coated cellophane / ethylene-vinyl acetate copolymer), and vacuum-packaged to obtain a package.

The obtained package is subjected to boil sterilization at 98 ° C. for 30 minutes to evaluate the moist heat blocking of the package immediately after the treatment and the whitening of the film (boil resistance). Further, the package is placed in a refrigerator at 2 ° C. After storage for one day, the gloss of the film and the surface of the film were labeled to evaluate the degree of adhesion (label adhesion).

Also, 20 pieces of the package after storage were placed in an A-type double cardboard case and dropped six times from a height of 1.5 m to evaluate occurrence of vacuum leakage (pinhole resistance). As a result of evaluation by the above method, boil resistance, gloss,
Both the label adhesion and the pinhole resistance were good. In addition, no pinhole was generated in the pinhole resistance.

Example 2 Layer configuration: Same as Example 1 except that the innermost layer is an ionomer and the thickness ratio is different. Thickness: 12 PA / AD / Nylon-6 / EVOH / AD / Ionomer (25 μm / 15 μm / 50 μm / 10 μm / 10 μm / 90 μm) Thickness ratio to the total thickness of the outermost layer = 12.5% After a package was obtained by the same method as in Example 1, evaluation was performed. As a result, the same boil resistance and gloss were obtained as in Example 1. , Label adhesion and pinhole resistance were all good.

Example 3 Layer structure: outermost layer (first layer): 12 PA layer, second layer: carboxylic acid-modified ethylene-vinyl acetate copolymer (AD), third layer: nylon 6, fourth layer: carbon Acid-modified ethylene
Vinyl acetate copolymer (AD), fifth layer: a configuration in which an ethylene-vinyl acetate copolymer (EVA) is provided. Thickness: 12 PA / AD / Nylon-6 / AD / EVA (10 μm / 15 μm / 60 μm / 10 μm / 105 μm) Thickness ratio to total thickness of outermost layer = 5% Example using composite film having the above layer configuration and thickness After obtaining a package in the same manner as in Example 1, evaluation was performed. As a result, as in Example 1, all of the boil resistance, gloss, label adhesion, and pinhole resistance were good.

Comparative Example 1 Layer configuration: The same contents as in Example 1 except that the outermost layer was made of nylon-6 and the thickness ratio was different. Thickness: Nylon-6 / AD / Nylon-6 / EVOH / AD / Ionomer (40 μm / 15 μm / 30 μm / 10 μm / 10 μm / 95 μm) Thickness ratio to the total thickness of the outermost layer = 20% Packaging by the same method as in Example 1. After the body was obtained, the evaluation was performed. As a result, it was inferior in the boil resistance and the pinhole resistance. (A pinhole was generated in 15% of the package.) Comparative Example 2 Layer configuration: Same as Example 3 except that the thickness ratio was different. Thickness: 12 PA / AD / Nylon-6 / AD / EVA (35 μm / 15 μm / 30 μm / 15 μm / 105 μm) Thickness ratio to the total thickness of the outermost layer = 17.5% A package was obtained in the same manner as in Example 1. Later, as a result of evaluation, the pinhole resistance was poor. (Pinholes occurred in 10% of the package.) Comparative Example 3 Layer composition: Dry laminate film composed of unstretched polypropylene / nylon-6 / ethylene-vinyl acetate copolymer Thickness: (30 μm / 60 μm / 110 μm) After a package was obtained in the same manner as in Example 1, the package was evaluated. As a result, the boil resistance and the pinhole resistance were excellent, but the gloss and the label adhesion were poor.

[0019]

As described above, the co-extruded composite film for deep drawing according to the present invention is excellent in gloss, transparency, label adhesion, pinhole resistance and the like, and is suitable for foods requiring boil sterilization treatment. It can be suitably used for packaging.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 27/32 B32B 27/32 101 101 27/34 27/34 // B29K 23:00 77:00 B29L 9:00 (56) References JP-A-5-169603 (JP, A) JP-A-6-293118 (JP, A) JP-A-6-190990 (JP, A) JP-A-4-345828 (JP, A) JP-A-58 -20444 (JP, A) JP-A-3-187743 (JP, A) JP-A-3-24954 (JP, A) JP-A-5-138812 (JP, A) JP-A 4-259547 (JP, A) JP-A-53-16067 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 47/06 B32B 27/08 B32B 27/28 102 B32B 27/32 B32B 27/34 B29B 11/10 B29C 51/14

Claims (3)

(57) [Claims] The outermost layer is a 12 nylon resin layer or 1 layer.
Copolyamide resin layer of 2 nylon and 6 nylon,
A polyamide resin layer having an intermediate layer sandwiched between polyolefin-based adhesive resin layers, or a polyamide resin layer and an ethylene-vinyl acetate copolymer saponified layer sandwiched between polyolefin-based adhesive resin layers, and a sealable resin layer disposed as an innermost layer. A co-extruded composite film for deep drawing, wherein the thickness of the outermost layer is 15% or less of the total thickness. 2. The co-extruded composite film for deep drawing according to claim 1, wherein the innermost sealing resin layer comprises an ionomer resin. 3. The outermost layer is a 12 nylon resin layer or 1
Copolyamide resin layer of 2 nylon and 6 nylon,
A polyamide resin layer having an intermediate layer sandwiched between polyolefin-based adhesive resin layers, or a polyamide resin layer and an ethylene-vinyl acetate copolymer saponified layer sandwiched between polyolefin-based adhesive resin layers, and a sealable resin layer disposed as an innermost layer. The thickness of the outermost layer is not more than 15% of the total thickness and not more than half of the thickness of the intermediate layer.
Or a co-extruded composite film for deep drawing according to claim 2;