JP2000052524A - Food packaging bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a food packaging bag excellent in label bonding strength and pinhole resistance. SOLUTION: In a food packaging container formed by heat-sealing an unstretched laminated film, the laminated film has at least a blend resin layer of a polyethylene naphthalate resin and a polyethylene terephthalate resin or a multilayered structure wherein a polybutylene terephthalate resin layer (A), a gas barrier resin layer (B) and a heat-sealable resin layer (C) are successively laminated and the layer (A) is arranged as the outermost layer and the layer (C) is arranged as the innermost layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a food packaging bag, and more particularly to a food packaging bag suitably used for producing, for example, ham and sausage.

Generally, ham and sausage are produced by filling a bag made of shrink film with raw materials and then heat-treating the bag in a retainer. Then, prior to shipping, a print label is attached to the bag surface. Since the adhesive strength of the label is affected by the moisture on the label application surface, the bag surface of the product taken out of the retainer can be drained enough so that it does not need to be dried before applying the label. desirable. Food packaging bags are required to have excellent pinhole resistance during transportation.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a food packaging bag excellent in label adhesive strength and pinhole resistance.

[0004]

That is, the gist of the present invention is a food packaging container obtained by heat-sealing an unstretched laminated film, wherein the laminated film has at least
A blend resin layer of a polyethylene naphthalate resin and a polyethylene terephthalate resin or a polybutylene terephthalate resin layer (A), a gas barrier resin layer (B),
It has a multilayer structure in which the heat-sealable resin layers (C) are sequentially laminated, and the (A) layer is disposed on the outermost layer, and the (C) layer is disposed on the innermost layer. Characteristic food packaging bag.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The food packaging bag of the present invention is formed by heat sealing an unstretched laminated film. The unstretched laminated film is made of at least polyethylene naphthalate (PE
N) a blend resin layer of a resin and a polyethylene terephthalate (PET) resin or a polybutylene terephthalate (PBT) resin layer (A), a gas barrier resin layer (B),
It has a multilayer structure in which a heat-sealing resin layer (C) is sequentially laminated. And in a preferred embodiment of the present invention,
An adhesive resin layer is disposed between the respective layers.

As the PEN resin, PET resin and PBT resin, known resins commonly used for various films can be used. The ratio of the PEN resin and the PET resin in the blend resin is usually 1: 0.5.
２2 weight ratio.

The gas barrier resin layer (B) is made of a polyamide (PA), a saponified ethylene-vinyl acetate copolymer (EV)
OH), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polycarbonate (PC). Among these, polyamide (PA) or saponified ethylene-vinyl acetate copolymer (EVOH) is preferred,
Particularly, polyamide (PA) is preferred.

In the present invention, a polyamide obtained by polycondensation of (1) a lactam having three or more ring members, (2) a polymerizable ω-amino acid, and (3) a polyamide material of diamine and dicarboxylic acid is used. Can be done.

Specific examples of the lactam having three or more rings include ε-caprolactam, enantholactam, α-pyrrolidone, α-piperidone and the like.
Specific examples of amino acids include 6-aminohexanoic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 9-aminononanoic acid.

Specific examples of the diamine include hexamethylene diamine, nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine, and meta-xylylene diamine. Examples of the dicarboxylic acid include terephthalic acid. , Isophthalic acid, adipic acid, sebacic acid, dodecane dibasic acid, glutaric acid and the like.

Specific examples of the polyamide used in the present invention include nylon 4, 6, 7, 8, 11, 12, 6.6,
6 ・ 10, 6 ・ 11, 6 ・ 12, 6T, 6/6 ・ 6, 6
/ 12, 6 / 6T, 6I / 6T and the like.

The heat-sealable resin layer (C) is usually made of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA). , Ethylene-methacrylate copolymer (EM
A), ethylene-ethyl acrylate copolymer (EE
A), ethylene-methacrylate copolymer (EMM)
A), ethylene-ethyl acrylate copolymer (EA)
A), ethylene-ethyl methacrylate copolymer (EMA)
A), adhesive polyethylene, ionomer resin, EVA
A saponified product, linear low-density polyethylene (L-LDPE) or a copolymer thereof is used. Among these, linear low-density polyethylene (L-LDPE) is preferred.

Linear low density polyethylene (L-LDPE)
Is a copolymer of ethylene and an α-olefin having 3 to 13 carbon atoms (ethylene content: 86 to 99.5 mol%), and has a low and medium density different from LDPE produced by a conventional high pressure method. It is polyethylene. High pressure LDPE and LL
The structural difference from DPE is that the former has a multi-branched molecular structure and the latter has a linear molecular structure.
In the production of LLDPE, α copolymerized with ethylene
-Examples of the olefin include butene-1, pentene-1, hexene-1, octene-1, and 4-methylpentene-1. These copolymerizations are carried out by a low to medium pressure method using a so-called Ziegler-Natta type catalyst.

If the specific examples of the above LLDPEs are represented by trade names, Unipole (UCC), Dourex (Dow Chemical), Screa (DuPont Canada), Marlex (Philips), Neozex and Ultrazex (Mitsui Petrochemical) ), Nisseki Linilex (Nippon Petrochemical), Stamilex (DSM) and the like.

The adhesive resin layer is usually made of a modified polyolefin resin (APO). Such APO is produced by copolymerizing and / or graft-polymerizing an α, β unsaturated carboxylic acid or a derivative thereof on a polyolefin resin containing an ethylene component and / or a propylene component as a main component.

Examples of the above polyolefin resin include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene- Ethyl acrylic acid copolymer, ethylene-
And sodium acrylate copolymer.

Examples of the α, β-unsaturated carboxylic acid or its derivative to be copolymerized include acrylic acid, methacrylic acid, methyl methacrylic acid, sodium acrylate, zinc acrylate, vinyl acetate, glycidyl methacrylate and the like. , Within the range of 40 mol% in the molecular chain. Examples of the copolymer-modified polyolefin resin include an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, an ethylene-ethyl acrylic acid copolymer, and an ethylene-sodium acrylate copolymer.

The above-mentioned grafted α, β-unsaturated carboxylic acid or a derivative thereof includes, for example, acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, anhydrides of these acids, or acids of these acids. And the like. Among these modifying compounds, maleic anhydride is particularly preferred. The amount of grafting is selected from the range of 0.01 to 25% by weight, preferably 0.05 to 1.5% by weight, based on the polyolefin resin.

The grafting reaction is carried out according to a conventional method, usually by melt-mixing a polyolefin resin and an α, β-unsaturated carboxylic acid or a derivative thereof at a resin temperature of 150 to 300 ° C. At the time of the graft reaction, 0.001-0.05% by weight of an organic peroxide such as α, α′-bis-t-butylperoxy-p-diisopropylbenzene is blended in order to carry out the reaction efficiently. Is good.

In the above non-laminated film, the layer (A) composed of a blend resin of a polyethylene naphthalate resin and a polyethylene terephthalate resin or a polybutylene terephthalate resin is composed of an outermost layer and a heat sealing resin. The (C) layer is disposed on the innermost layer, and the (B) layer composed of a gas barrier resin is disposed on these intermediate layers. (A) The thickness of the layer is usually 5 to 5.
100 μm, preferably 10 to 70 μm, the thickness of the layer (B) is usually 5 to 50 μm, preferably 10 to 30 μm,
The thickness of the layer (C) is usually 20 to 100 μm, preferably 30 to 70 μm. In a preferred embodiment, the thickness of the adhesive resin layer disposed between the respective layers is usually 2 to 3.
It is 30 μm, preferably 5 to 15 μm.

The food packaging bag of the present invention is produced, for example, by manufacturing a laminated film cylinder by downward water-cooling molding using a co-extruded annular die, and then heat-sealing the end of the cylinder. You. The laminated film may be manufactured by a T-die method. And the above-mentioned heat sealing is usually performed as gusset processing. The coextrusion molding method and the gusset processing described above are each a known technique, and preferred embodiments thereof are as follows.

That is, the above-mentioned coextrusion method is usually
A water tank provided with a size ring therein is arranged below the annular die, and a device having an inner plate and a winding roll arranged sequentially below the water tank is used. After co-extruding the kinds of raw resin so that stretching does not occur substantially, passing through between the size rings and cooling, the cylindrical body of the laminated film is supplied to the take-up roll through the inner plate and folded, This is a method of winding up as a double film. Therefore, the obtained laminated film is a substantially unstretched film, and in a preferred embodiment thereof,
Heat shrinkage (J) in the length direction (MD) and width direction (TD)
IS K 6734) is 5% or less.

Gusset processing is a processing method in which the end of a cylindrical body is folded and sealed. In the case of ordinary gusset processing, the end of the cylindrical body is formed in a square shape, and two opposing sides are formed by those two sides. The valley is folded substantially from the center, and the other two sides are overlapped with each other.

The food packaging bag of the present invention is suitably used for producing, for example, ham and sausage.
Since the outermost layer is made of a blend resin of N resin and PET resin or a PBT resin, it has a feature that the label adhesive strength immediately after being taken out from the retainer is excellent. Such a feature is presumed to be based on the reason that the resin constituting the outermost layer drains extremely well. However, as shown in a comparative example described later, for example, the same type of PET resin or PEN as the PBT resin is used. The fact that this is not achieved by the resin but by these blended or PBT resins is a very surprising fact.

In particular, the food packaging bag of the present invention in which the outermost layer is made of a PBT resin is characterized in that the laminated film itself has excellent curl resistance. That is, the outermost layer is PB
In the case of a food packaging bag made of a resin other than the T resin, the open end of the gusset bag may be curled and hinder the filling of the raw material. It does not occur in packaging bags.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 A downward water-cooling molding method using a five-layer co-extrusion annular die was used.
PBT (8 μm) / APO (6 μm) / NY: Nylon 6 (16 μm) / APO (6 μm) / L-LDPE (4
(4 μm) was produced. The extrusion temperature was 240 ° C, the water cooling temperature was 28 ° C, and the winding speed was 15 m / min. And The obtained cylindrical body is slit to a predetermined length, and one end thereof is subjected to gusset processing with a linear heat seal along the end, and the outermost layer is formed of PBT.
As a result, a gusset bag having an innermost layer of L-LDPE was obtained.

After filling the gusset bag with the previously cooked ham raw material, the gusset bag is set in a retainer and heated.
The length and width of the central part in the longitudinal direction are both 8 cm and the total length is 35 c
m square hams were produced. The resulting ham product was evaluated for label adhesive strength, pinhole resistance and curl resistance by the following methods (1) to (4). The results are shown in Table 2.

(1) Label adhesive strength: A label is attached to the surface of a ham product bag immediately after being taken out of the retainer,
The peel strength (g / 15 mm) was measured.

(2) Pinhole resistance: 10 cases (10
(Bags / cases), a refrigerated transport test at -20 ° C (Shikoku 1 yen) was performed, and the number of bags broken during transport was evaluated.

(3) Curling property: The curling state of the open end of the gusset bag was visually observed.

Example 2 and Comparative Examples 1 to 3 Except that the type of the resin in the outermost layer was changed as shown in Table 1,
After obtaining a gusset bag in the same manner as in Example 1, a ham product was manufactured. The resulting ham product was evaluated for label adhesive strength, pinhole resistance and curl resistance, and the results are shown in Table 2.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

According to the present invention described above, a food packaging bag excellent in label adhesive strength and pinhole resistance is provided.

Claims (1)

[Claims] 1. A food packaging container obtained by heat-sealing an unstretched laminated film, wherein the laminated film comprises at least a blended resin layer of a polyethylene naphthalate resin and a polyethylene terephthalate resin or a polybutylene terephthalate resin layer ( A), a gas barrier resin layer (B), and a heat sealing resin layer (C) are sequentially laminated, and the above-mentioned (A) layer is disposed on the outermost layer, and the above-mentioned (C) A food packaging bag, wherein the layer is disposed on the innermost layer.