JP3051614B2 - Co-extruded 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 so-called steam package in which the contents are stored in a bottom material obtained by deep drawing, the lid material is sealed, and vacuum packaging is performed while spraying steam. The present invention relates to a co-extruded composite film for deep drawing, which can be used for a shrink packaging method and can be suitably used for a sliced ham stack package obtained by such a steam shrink packaging method.

[0002]

2. Description of the Related Art A large number of so-called sliced ham stacks, in which a plurality of sliced hams are stacked and packed, are sold in stores such as supermarkets because of their excellent appearance and easy handling. Such a sliced ham stack package is usually formed by forming a bottom material by deep drawing using a composite film having various layer constitutions, stacking and storing the sliced hams, sealing the lid material and vacuum packaging. Has been made.

[0003] In the above method, vertical wrinkles are liable to occur in the direction parallel to the squeezing on the side surface of the cross-section concave portion of the bottom material obtained by deep drawing, and drip is formed between the contents and the contents.
In particular, there is a problem that pinholes are generated at the contact point with the flange portion of the lid material when the degree of vertical wrinkles is severe.

[0004] As a means for solving the above problem, a so-called steam shrink packaging method is known in which a lid material is sealed and vacuum packaging is performed while spraying high-temperature steam. In this method, the wrinkles on the side portions can be eliminated by the shrinkage of the bottom material, but depending on the composite film used, the shrinkage is too large and radial wrinkles on the bottom portion of the bottom material outward from the center. When this occurs and the shrinkage is remarkable, there is a problem that the stored sliced ham becomes trapezoidal. Further, there has been a problem that the surface of the composite film is whitened by steam to reduce the transparency, and dew condensation occurs on the surface due to the steam, so that it is difficult to attach a label.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to find a co-extruded composite film for deep drawing which can be suitably used for a sliced ham stack package which performs steam shrinking and which can solve the above-mentioned problems. However, the innermost layer is a heat-sealable resin layer, the opposite outermost layer is an amorphous polyester resin layer, and the middle layer is a polyamide resin layer or a barrier layer comprising a polyamide resin layer and a saponified ethylene vinyl acetate copolymer layer. A conductive resin layer,
A polyolefin-based adhesive resin layer is disposed between the outermost layer and the intermediate layer and between the heat-sealing 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. A co-extruded composite film for deep drawing.

[0006] Amorphous polyester resin (hereinafter "Amorphous P"
The “ES”) is disposed on the outermost layer because it has the advantages that the film is not whitened by steam shrink, has good transparency, and that dew condensation on the film surface due to steam hardly occurs and labeling is easy. is there. Amorphous PE
As S, an amorphous PES comprising terephthalic acid as an acid component, ethylene glycol and 1,4-cyclohexanedimethanol as an alcohol component can be suitably used.

The thickness of the amorphous PES must 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 steam shrinkage is too large, so that there is a problem that radial wrinkles are likely to be generated at the bottom. There is a problem that vertical wrinkles occur. A specific thickness in the range of 5 to 20 μm can be suitably used.

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

Here, if 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 cover material Thus, there is an advantage that the sealing strength is hardly influenced, and in particular, those having a vinyl acetate content of 4 to 8% by weight can be suitably used. If the content is less than 4% by weight, the sealing strength is low, and if it exceeds 8% by weight, there is a problem that the odor of vinyl acetate becomes strong.

Further, as the heat-sealing resin layer,
When low-density polyethylene or linear low-density polyethylene is used, there is an advantage that it is possible to prevent the resin from being removed from the hot plate at the time of 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. If the ratio exceeds, there is a problem that the moldability is inferior.

The intermediate layer of the composite film of the present invention is a barrier resin layer, and comprises a polyamide resin layer or a saponified ethylene vinyl acetate copolymer (hereinafter referred to as "EVO").
H ”). As the polyamide resin, nylon 6, nylon 66, nylon 6/6
6, nylon 6T / 6I and the like can be suitably used. EVO
As H, those having an ethylene content of 30 to 60 mol% and a degree of saponification 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. In the case of the polyamide layer and the EVOH layer, the thickness of the polyamide resin layer is 7 to 25 μm and the thickness of the EVOH layer is 10 to 30 μm. 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. As the polyolefin-based adhesive resin to be used, an unsaturated carboxylic acid or a derivative thereof is used. An acid-modified polyolefin resin grafted with at least one monomer selected from the following can be suitably used, and can firmly bond the amorphous PES layer, the intermediate layer, and the heat-sealing resin layer. 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. Here, the overall thickness of the composite film having the above layer configuration is 80 to 180 μm.
Those in the range described above can be suitably used.

In the present invention, since the resin layers having the above constitutions are laminated by a co-extrusion method, a composite film excellent in both physical properties and appearance having good transparency, gloss, deep drawability, pinhole resistance and the like can be obtained. .

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

[0016]

【Example】

Example 1 Layer Configuration: Outermost Layer (First Layer): Amorphous PES (Kodahl P
ETG, manufactured by Kodak Co., Ltd.), second layer: carboxylic acid-modified ethylene-vinyl acetate copolymer (AD), third layer: nylon 6/66, fourth layer: EVOH, fifth layer: carboxylic acid-modified Ethylene-vinyl acetate copolymer (AD), innermost layer (sixth layer): ethylene-vinyl acetate content of 5% by weight
A configuration in which a vinyl acetate copolymer (EVA) is provided.

Thickness: amorphous PES / AD / nylon 6
−66 / EVOH / AD / EVA (7 μm / 10 μm / 15 μm / 30 μm / 1
0 μm / 88 μm) The ratio of the total thickness of the amorphous PES layer to the total thickness = 4.4% The composite film having the above configuration was formed by a coextrusion molding method. Then, the composite film is placed so that the first layer is on the outside,
Deep drawing packaging machine (R-7000) manufactured by Mulchivac Co., Ltd.
100mm diameter, 20mm depth bottom material at a molding temperature of 85
It was drawn at ℃. Eight sliced hams are filled in the formed hole, covered with a lid material (dry laminate film made of unstretched polypropylene / K-coated cellophane / ethylene-vinyl acetate copolymer), and sliced ham stack package by vacuum packaging. I got In this case, steam shrink was performed by spraying steam into the vacuum chamber during vacuum packaging.

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

Example 2 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 described below, and the same evaluation as in Example 1 was performed.

Thickness: amorphous PES / AD / nylon 6
−66 / EVOH / AD / EVA (25 μm / 10 μm / 15 μm / 25 μm /
(10 μm / 75 μm) Ratio to the total thickness of the amorphous PES layer = 15.7% The shrinkage when the molded article was treated with hot water at 70 ° C. for 30 seconds was 1
0.4% was good, and there were no radial wrinkles or radial wrinkles on the bottom side surface of the sliced ham stack package.
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: a seven-layer structure in which a carboxylic acid-modified ethylene-vinyl acetate copolymer (modified EVA) having a vinyl acetate content of 5% by weight was further provided as the innermost layer in the layer structure of Example 1. . 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 to the total thickness of the amorphous PES layer = 9.4% The shrinkage when the molded article was treated with hot water at 70 ° C. for 30 seconds was 1
As good as 1.6%, there was no problem in evaluation as a sliced ham stack package as in Example 1. Further, even if a material having a different layer structure from that of Example 1 was used as the lid material, there was no problem in the sealing property.

Example 4 A seven-layer structure in which linear low-density polyethylene (LLDPE) is further disposed 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 to the total thickness of the amorphous PES layer = 9.4% The shrinkage when the molded article was treated with hot water at 70 ° C. for 30 seconds was 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 increased, it was not removed to the hot plate, and the efficiency of the packaging operation was improved.

Comparative Example 1 A sliced ham stack package was obtained in the same manner as in Example 1 except that the thickness composition of each layer was as described below, 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 to the total thickness of the amorphous PET layer = 3.1% The shrinkage when the molded article was treated with hot water at 70 ° C. for 30 seconds was 1
Although it was too high as 3.1%, there was no vertical wrinkle on the side of the bottom material of the sliced ham stack package, but radial wrinkles were generated on the bottom. There was no problem with the transparency and gloss of the film and the adhesiveness of the label.

Comparative Example 2 A sliced ham stack package was obtained in the same manner as in Example 1 except that the thickness 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 (35 μm / 10 μm / 15 μm / 30 μm /
(10 μm / 60 μm) Ratio to the total thickness of the amorphous PET layer = 21.8% The shrinkage ratio when the molded article is treated with hot water at 70 ° C. for 30 seconds is as low as 9.8%, which is lower 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 was no problem with the transparency and gloss of the film and the adhesiveness of the label.

Comparative Example 3 EVOH (2) was used instead of amorphous PET as the outermost layer (first layer).
A package was obtained and evaluated in the same manner as in Example 2 except that 5 μm) was used.

When the molded article was treated at 70 ° C. for 30 seconds with hot water for 30 seconds, the shrinkage was too high, 13.5%, and there was no vertical wrinkle on the side of the bottom material of the sliced ham stack package. Wrinkles had occurred. The transparency and gloss of the film were poor due to whitening, and the adhesion of the label was poor.

[0029]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-166942 (JP, A) JP-A-4-153022 (JP, A) JP-A-60-56549 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (3)

(57) [Claims] 1. An innermost layer comprising a heat-sealable resin layer, an opposite outermost layer comprising an amorphous polyester resin layer, and an intermediate layer comprising a polyamide resin layer or a polyamide resin layer and a saponified ethylene vinyl acetate copolymer 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 thickness of the amorphous polyester resin layer is complex. A co-extruded composite film for deep drawing, wherein the thickness is in the range of 4 to 18% of the total thickness of the film. 2. The deep drawing according to claim 1, wherein an acid-modified ethylene-vinyl acetate copolymer having a vinyl acetate content in the range of 4 to 8% by weight is used as the heat-sealing resin layer. For co-extrusion composite film. 3. A low-density polyethylene or a linear low-density polyethylene is used as the heat-sealing resin layer, and the thickness of the heat-sealing resin layer is 10 to 40% of the total thickness of the polyolefin resin layer in the composite film. 2. The co-extruded composite film for deep drawing according to claim 1, wherein the thickness is within the range.