JPH0796582A - Coextrusion composite film for deep drawing - Google Patents

Abstract

(57) [Summary] [Purpose] After the contents are stored in the bottom material obtained by deep drawing, the lid material is sealed and vacuum-packed while spraying steam, which is suitable for the so-called steam shrink packaging method. A coextrusion composite film for drawing is provided. A barrier comprising a heat-sealing resin layer as an innermost layer, an amorphous polyester resin layer as an outermost layer, and a polyamide resin layer or a polyamide resin layer and a saponified ethylene vinyl acetate copolymer layer as an intermediate layer. A resinous resin layer, and a polyolefin-based adhesive resin layer between the outermost layer and the intermediate layer, and between the heat-sealable resin layer and the intermediate layer. A coextrusion composite film for deep drawing, characterized in that the thickness is in the range of 4 to 18%. [Effect] The steam shrink packaging method does not cause vertical wrinkles on the side surface of the bottom material or radial wrinkles on the bottom, and can be suitably used for sliced ham stack packages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coextruded composite film, and in particular, a so-called steam which is used for vacuum packaging while containing a content in a bottom material obtained by deep drawing and then sealing a lid material and spraying steam. The present invention relates to a coextruded composite film for deep drawing, which can be used in the shrink wrapping method and can be preferably used in a sliced ham stack package obtained by such a steam shrink wrapping method.

[0002]

BACKGROUND OF THE INVENTION A large number of so-called sliced ham stack packages, in which a plurality of sliced hams are stacked and packaged, are sold in stores such as supermarkets because of their excellent appearance and easy handling. Such sliced ham stack packaging is usually formed by deep drawing using a composite film composed of various layers, and after stacking the sliced ham, the lid is sealed and vacuum packed. Has been done.

In the above method, vertical wrinkles are likely to occur in the side surface of the cross-section recess of the bottom material obtained by deep drawing in a direction parallel to the drawing, and gravy (drip) is formed between the content and the content.
However, there is a problem that pinholes are generated at the contact points with the flange portion of the lid material, especially when the degree of vertical wrinkles is severe.

As a means for solving the above problems, there is known a so-called steam shrink packaging method in which a lid member is sealed and vacuum packaging is performed while spraying high temperature steam. In this method, it is possible to eliminate vertical wrinkles on the side surface by shrinking the bottom material, but depending on the composite film used, the shrinkage is too large, and the bottom of the bottom material has radial wrinkles extending outward from the center. When the shrinkage occurs and the shrinkage is remarkable, there is a problem that the stored sliced ham has a trapezoidal shape. Further, there is a problem that the surface of the composite film is whitened by steam and the transparency is lowered, and that steam causes dew condensation on the surface to make it difficult to attach a label.

[0005]

DISCLOSURE OF THE INVENTION The present invention has found out a coextruded composite film for deep drawing which can be suitably used for a slice ham stack package for steam shrinking which can solve the above problems, and its gist is to be summarized. However, the innermost layer is a heat-sealable resin layer, and the opposite outermost layer is an amorphous polyester resin layer, and the intermediate layer is a barrier layer composed of a polyamide resin layer or a polyamide resin layer and a saponified ethylene vinyl acetate copolymer layer. A resin layer,
A polyolefin-based adhesive resin layer is provided between the outermost layer and the intermediate layer, and between the heat-sealable resin layer and the intermediate layer, and the thickness of the amorphous polyester resin layer is 4 to 18% of the total thickness of the composite film. The coextruded composite film for deep drawing is characterized in that it is in the range.

Amorphous polyester resin (hereinafter "amorphous P"
"ES") is placed on the outermost layer because it has good transparency because it does not whiten due to steam shrink, and it is easy to label because steam does not cause condensation on the film surface. is there. Amorphous PE
As S, terephthalic acid as an acid component, ethylene glycol as an alcohol component, and amorphous PES composed of 1,4-cyclohexanedimethanol can be suitably used.

The thickness of this amorphous PES needs to be in the range of 4 to 18% of the total thickness of the composite film.
If it is less than 4%, the shrinkage of the film due to the steam shrink is too large, so that there is a problem that radial wrinkles are likely to occur at the bottom, and if it exceeds 18%, the shrinkage of the film due to the steam shrink is too small and the side surface of the bottom material is too small. There is a problem that vertical wrinkles occur at. A specific thickness is preferably in the range of 5 to 20 μm.

Ionomer resin, polyethylene, ethylene-vinyl acetate copolymer, low-density polyethylene, linear low-density polyethylene, etc. can be used for the innermost heat-sealable resin layer, and the thickness is preferably in the range of 40 to 80 μm. Can be used.

Here, when the resin used is an acid-modified ethylene-vinyl acetate copolymer grafted with at least one monomer selected from unsaturated carboxylic acids or derivatives thereof, the type of resin used for the sealing layer of the lid material This has the advantage that the sealing strength is less likely to be affected, and in particular, those having a vinyl acetate content in the range of 4 to 8% by weight can be preferably used. If the content is less than 4% by weight, the sealing strength will be weak, and if it exceeds 8% by weight, the odor of vinyl acetate will be strong.

Further, as the heat sealable resin layer,
The use of low-density polyethylene or linear low-density polyethylene has an advantage that the resin can be prevented from being taken up by the hot plate during drawing without lowering the sealing property. In this case, the thickness of the heat-sealable resin layer is preferably in the range of 10 to 40% of the total thickness of the polyolefin resin layer in the composite film, and if it is less than 10%, film formation is difficult and 40%. If it exceeds, there is a problem that the moldability is poor.

The intermediate layer of the composite film of the present invention is a barrier resin layer and comprises a polyamide resin layer or a polyamide resin layer and a saponified ethylene vinyl acetate copolymer (hereinafter referred to as "EVO").
"H") layer. As polyamide resin, nylon 6, nylon 66, nylon 6/6
6, nylon 6T / 6I and the like can be preferably used. EVO
As H, those having an ethylene content of 30 to 60 mol% and a saponification degree of 95% or more are preferable from the viewpoint of moldability and barrier properties.

The thickness of the intermediate layer may be in the range of 10 to 30 μm in the case of only the polyamide resin layer, and in the case of the polyamide resin layer and the EVOH layer, the thickness of the polyamide resin layer is 7 to 25 μm and the EVOH layer is 10 to 10. The range may be 30 μm.

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. The polyolefin-based adhesive resin used is an unsaturated carboxylic acid or a derivative thereof. An acid-modified polyolefin resin grafted with at least one monomer selected from the following can be preferably used, and the amorphous PES layer, the intermediate layer, and the heat-sealable resin layer can be firmly adhered to each other. Further, by disposing the polyolefin-based adhesive resin layer having excellent pinhole resistance on both sides of the barrier resin layer where pinholes are likely to occur, the pinhole resistance of the entire film can be improved. The thickness of each polyolefin-based adhesive resin layer may be in the range of 5 to 20 μm. Here, the total thickness of the composite film having the above layer structure is 80 to 180 μm.
Those in the range of can be preferably used.

In the present invention, since the resin layers having the above-mentioned constitution are laminated by the coextrusion method, a composite film having excellent physical properties such as transparency, luster, deep drawing formability, pinhole resistance and the like and an excellent appearance can be obtained. .

The present invention will be described below with reference to examples.

[0016]

【Example】

Example 1 Layer structure: Outermost layer (first layer): Amorphous PES (Kodar P
ETG, manufactured by Kodak Co., Ltd., 2nd layer: carboxylic acid modified ethylene-vinyl acetate copolymer (AD), 3rd layer: nylon 6/66, 4th layer: EVOH, 5th layer: carboxylic acid modified Ethylene-vinyl acetate copolymer (AD), innermost layer (sixth layer): ethylene with a vinyl acetate content of 5% by weight
A structure in which a vinyl acetate copolymer (EVA) is arranged.

Thickness: amorphous PES / AD / nylon 6
-66 / EVOH / AD / EVA (7 μm / 10 μm / 15 μm / 30 μm / 1
0 μm / 88 μm) Ratio of the amorphous PES layer to the total thickness = 4.4% The composite film having the above-mentioned constitution was formed by a coextrusion molding method. Then put the composite film so that the first layer is on the outside,
Deep drawing packaging machine (R-7000) made by Multibag Co., Ltd.
At a forming temperature of 85 mm
It was drawn at a temperature of ℃. 8 sliced hams were filled in the formed holes, covered with a lid material (non-stretched polypropylene / K-coated cellophane / dry laminate film consisting of ethylene-vinyl acetate copolymer), and vacuum-packaged sliced ham stack packaging Got In this case, steam shrink was performed by spraying steam into the vacuum chamber during vacuum packaging.

Here, when the molded product obtained by the above method without containing the contents was treated with hot water at 70 ° C. for 30 seconds, the shrinkage rate was as good as 12.8%. Further, the sliced ham stack package obtained by the above method had no vertical wrinkles on the side surface of the bottom material or radial wrinkles. Further, the film was excellent in transparency and gloss, and when the label was attached to the surface, the label was not easily peeled off and there was no problem in adhesiveness.

Example 2 A sliced ham stack package was obtained with the same contents as in Example 1 except that the thickness constitution of each layer was as follows, and the same evaluation as in Example 1 was carried out.

Thickness: amorphous PES / AD / nylon 6
-66 / EVOH / AD / EVA (25 μm / 10 μm / 15 μm / 25 μm /
10 μm / 75 μm) Ratio of the amorphous PES layer to the total thickness = 15.7% The shrinkage rate when the molded product is treated with hot water at 70 ° C. for 30 seconds is 1
It was as good as 0.4%, and there were no vertical wrinkles or radial wrinkles on the side surface of the bottom material of the sliced ham stack package.
Also, as in Example 1, there was no problem in the transparency and gloss of the film and the adhesiveness of the label.

Example 3 Layer Structure: In the layer structure of Example 1, a 7-layer structure further comprising a carboxylic acid-modified ethylene-vinyl acetate copolymer (modified EVA) having a vinyl acetate content of 5% by weight as the innermost layer. . Thickness: Amorphous PES / AD / Nylon 6-66 / EVO
H / AD / EVA / denatured EVA 15 μm / 10 μm / 15 μm / 25 μm / 10 μ
m / 65 μm / 20 μm Ratio of the amorphous PES layer to the total thickness = 9.4% The shrinkage rate when the molded product was treated with hot water at 70 ° C. for 30 seconds was 1
The result was as good as 1.6%, and the evaluation as a sliced ham stack package had no problem as in Example 1. Furthermore, even if a lid material having a layer structure different from that of Example 1 was used, there was no problem in the sealing property.

Example 4 A seven-layer structure in which a linear low-density polyethylene (LLDPE) is further arranged as the innermost layer in the layer structure of Example 1. Thickness: Amorphous PES / AD / Nylon 6-66 / EVO
H / AD / EVA / LLDPE 15 μm / 10 μm / 15 μm / 25 μm / 10 μ
m / 70 μm / 15 μm Ratio of amorphous PES layer to the total thickness = 9.4% Shrinkage rate when the molded product is treated with hot water at 70 ° C. for 30 seconds is 1
As good as 1.4%, there was no problem in evaluation as a sliced ham stack package as in Example 1. Furthermore, even if the molding temperature was raised, the heat plate was not caught and the packaging work was made more efficient.

Comparative Example 1 A sliced ham stack package was obtained in the same manner as in Example 1 except that the thickness constitution of each layer was as follows, and the same evaluation as in Example 1 was performed.

Thickness: amorphous PES / AD / nylon 6
-66 / EVOH / AD / EVA (5 μm / 10 μm / 15 μm / 30 μm /
10 μm / 90 μm) Ratio of amorphous PET layer to the total thickness = 3.1% The shrinkage ratio when the molded product is treated with hot water at 70 ° C. for 30 seconds is 1
It was too high as 3.1%, and there were no vertical wrinkles on the side surface of the bottom material of the sliced ham stack package, but radial wrinkles were generated on the bottom. There were no problems with the transparency and gloss of the film and the adhesiveness of the label.

Comparative Example 2 A sliced ham stack package was obtained with the same contents as in Example 1 except that the thickness constitution of each layer was as follows, and the same evaluation as in Example 1 was carried out.

Thickness: amorphous PES / AD / nylon 6
-66 / EVOH / AD / EVA (35 μm / 10 μm / 15 μm / 30 μm /
10 μm / 60 μm) Ratio of the amorphous PET layer to the total thickness = 21.8% The shrinkage rate when the molded product is treated with hot water at 70 ° C. for 30 seconds is as low as 9.8%, which is at the bottom of the sliced ham stack package. There were no radial wrinkles, but vertical wrinkles occurred on the side of the bottom material. There were no problems with the transparency and gloss of the film and the adhesiveness of the label.

Comparative Example 3 EVOH (2) was used in place of the amorphous PET of the outermost layer (first layer).
5 μm) was used, and a package was obtained and evaluated in the same manner as in Example 2.

When the molded product was treated with hot water at 70 ° C. for 30 seconds, the shrinkage rate was too high as 13.5%, and there was no vertical wrinkle on the side surface of the bottom material of the sliced ham stack package, but there was a radial pattern on the bottom. There were wrinkles. The transparency and gloss of the film were whitened and bad, and the adhesiveness of the label was bad.

[0029]

As described above, according to the deep-drawing coextrusion composite film of the present invention, vertical wrinkles do not occur at the side surface of the bottom material or radial wrinkles even at the steam shrink packaging method, There is an advantage that it can be suitably used for a sliced ham stack package.

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Claims (3)

[Claims] 1. A heat-sealable resin layer as an innermost layer, an amorphous polyester resin layer as an outermost layer, and a polyamide resin layer or a polyamide resin layer and a saponified ethylene vinyl acetate copolymer layer as an intermediate layer. And a polyolefin-based adhesive resin layer between the outermost layer and the intermediate layer and between the heat-sealable resin layer and the intermediate layer, and the amorphous polyester resin layer has a composite thickness. A coextrusion composite film for deep drawing, which is in the range of 4 to 18% of the total film thickness. 2. The deep-draw molding according to claim 1, wherein an acid-modified ethylene-vinyl acetate copolymer having a vinyl acetate content of 4 to 8% by weight is used as the heat-sealable resin layer. Co-extrusion composite film. 3. A low-density polyethylene or a linear low-density polyethylene is used as the heat-sealable resin layer, and the thickness of the heat-sealable resin layer is 10 to 40% of the total thickness of the polyolefin resin layers in the composite film. The coextrusion composite film for deep drawing according to claim 1, which is in the range.