JPH0380105B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sterile packaging bag that generates little odor during radiation sterilization.

Conventional methods for sterilizing sealed bags include ethylene oxide gas sterilization, ultraviolet sterilization, and gamma ray sterilization. However, in the ethylene oxide gas sterilization method, residual ethylene oxide gas tends to be a problem, and therefore various methods have been taken to reduce the residual gas. Furthermore, in the ethylene oxide gas sterilization method, packaging in a sealed bag with a gas barrier opening is practically impossible because ethylene oxide gas is difficult to penetrate through the gas barrier film.

Furthermore, although complete sterilization is difficult with the ultraviolet sterilization method, there is also a method in which ultraviolet rays are irradiated from the outside of a sealed bag with a mouth opening and the inside of the bag is sterilized through a film. In this case, a sealed bag with a mouth made of low-density polyethylene or ethylene-vinyl acetate copolymer, which has high UV transmittance, and a film with low gas barrier properties can sterilize to some extent, but the gas barrier is metal vapor deposited layer with
In the case of a sealed bag with a mouth made of aluminum foil, a vinylidene chloride coating layer, or a polyamide film, ultraviolet rays hardly pass through the bag, so sterilization using ultraviolet rays is impossible.

In addition, in the case of radiation sterilization, during the radiation irradiation,
Ethylene-vinyl acetate copolymers, etc., which are an important health element in sealed bags with openings, emit odors, making it difficult to put food into these bags in practice.
To prevent this odor, we conducted a lot of research and devised a method to sterilize the bag by placing a sealed bag with an oxygen absorber inside a bag containing an oxygen absorber and irradiating it with radiation in an oxygen-free environment. However, with this method, it is impossible to package the product in a sealed bag with a gas barrier opening because it is difficult to apply the action of the oxygen scavenger to the inside of the bag through the gas barrier film.

The present inventor conducted research to eliminate the odor generated when sterilizing sealed bags with gas barrier properties by radiation, and found that a copolymer film of polyolefin film, ethylene, and α-olefin having 3 to 10 carbon atoms was used. According to the sterile packaging bag, which is made of a laminated film laminated with a gas barrier film interposed therebetween and is made such that the copolymer film surface is on the inside of the bag, the bag can be used when irradiated with radiation. They have discovered that the generation of odors inside the bag can be reduced, and that the gas barrier film, which is the middle layer of the laminated film, completely prevents odors from outside the bag from transferring to the packaged items. The present invention was completed based on this knowledge.

That is, the gist of the present invention is a laminated film in which a co-assembly film of a polyolefin film, ethylene, and an α-olefin having 3 to 10 carbon atoms are laminated with a gas barrier film interposed therebetween; This is a sterile packaging bag characterized by comprising a bag body made so that the combined film surface constitutes the inner surface of the bag.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

1 and 2 show a sterile packaging bag according to the present invention, FIG. 1 is a perspective view, and FIG. 2 is an A shown in the first drawing.
- It is a sectional view taken along the line A.

The sterile packaging bag 9 of the present invention is composed of a laminated film 4 in which a polyolefin film 1 and a copolymer film 3 of ethylene and α-olefin having 3 to 10 carbon atoms are laminated with a gas barrier film 2 interposed therebetween. A bag body 6 made into a bag such that the copolymer film 3 side of the film 4 constitutes the inner surface of the bag.
It consists of

In addition, in FIG. 1, 5 is the seal portion of the bag body 6;
7 indicates a spout, and 8 indicates a cap.

Therefore, in the present invention, ethylene and carbon number 3
~10 α-olefin copolymer 3 is a so-called low-density linear polyethylene copolymer containing ethylene as the main component and carbon numbers such as propylene, butene, pentene, hexene, octene, nonene, decene, 4-methylpentene-1, etc. is a copolymer with an α-olefin having an α-olefin of 3 to 10, preferably a resin having a density of 0.910 to 0.939 g/cc, produced by polymerization in the presence of a stereospecific catalyst (such as a Ziegler type catalyst).

Next, the gas barrier film 2 is made of, for example, aluminum foil and stretched polypropylene bonded together, aluminum vapor-deposited stretched polyamide, vinylidene chloride coated stretched polyamide, ethylene-vinyl acetate copolymer saponified film, and ethylene-vinyl acetate copolymer saponified film. Co-extrusion film of vinyl acetate copolymer and saponified ethylene-vinyl acetate copolymer, polyamide film, co-extrusion film of polyamide and ethylene-vinyl acetate copolymer,
A coextruded film of vinylidene chloride and polyethylene can be used.

That is, the gas barrier film is composed of a gas barrier layer and a film supporting the gas barrier layer.

And the oxygen permeability through this gas barrier layer is
50c.c./m ² , 24hr or less is preferable.

The film supporting the gas barrier layer may be placed on either the polyolefin film side or the copolymer film of ethylene and α-olefin having 3 to 10 carbon atoms side of the gas barrier layer. This is because, although the supporting film may be, for example, a stretched polyamide film, an unstretched polyamide film, a stretched polyester film, etc., it generates almost no odor during radiation irradiation compared to an olefin film.

Next, as the polyolefin film 1, low density polyethylene, high density polyethylene, polypropylene, ethylene vinyl acetate copolymer, ionomer resin, copolymer film of ethylene and α-olefin having 3 to 10 carbon atoms, etc. can be applied. In the case of a sealed bag with a spout, it is desirable to use a film suitable for a sealed bag with a spout, such as an ethylene-vinyl acetate copolymer film.

Films such as ethylene-vinyl acetate copolymer film have good impact resistance and pinhole resistance, and when made into sealed bags with openings, they are free from pinholes caused by vibration during transportation and breakage caused by drops. It has sufficient protection against liquid leakage. If this condition is satisfied, a copolymer film of ethylene and α-olefin having 3 to 10 carbon atoms can be used as the polyolefin film in the sealed bag with a closure. Furthermore, depending on the size of the sealed bag, it is not necessary to use a polyolefin film that is best suited for sealed bags as long as the strength is satisfactory, and simple low-density polyethylene may be used.

Next, when laminating the films constituting the laminated film, an adhesive layer may or may not be provided. For example, a polyether polyol urethane adhesive may be used as the seating layer. This is because these also have almost no odor generated during radiation irradiation. By using a laminated film with the above specifications, it is possible to reduce the odor generated during radiation irradiation. In other words, the innermost layer of this laminated film generates less odor due to radiation irradiation, and even though the outermost layer is a film that generates odor, the odor generated from this layer is absorbed by the middle layer, which is a gas barrier layer film, which is sealed in a sealed bag with a opening. This prevents the odor from spreading to the innermost part of the container, and the odor does not transfer even when the food contents are filled.

The sterile packaging bag of the present invention is not limited to a sealed bag with a spout, but also includes a sealed bag without a spout.

Furthermore, the sterile packaging bag of the present invention is not limited to a single-layer bag, but may be a laminated bag in which a polyolefin film, a copolymer film of ethylene, and an α-olefin having 3 to 10 carbon atoms are laminated with a gas barrier film interposed therebetween. It also includes double bags made by laminating a film with another film on the outside.

Further, when forming a sealed bag with a spout according to the present invention, the spout and cap are preferably made of a copolymer resin of ethylene and α-olefin having 3 to 10 carbon atoms.

Next, the radiation to be irradiated to sterilize the sterile packaging bag of the present invention includes ionizing radiation such as gamma rays and electron beams. The radiation dose is normal for sterilization.
A value of 3.0 Mrad or less is sufficient, but a value higher than that is also acceptable. However, since the generation of odor tends to increase with the irradiation dose, it is desirable to irradiate at as low a dose as possible even if a film with very low odor generation is used.

It is also important to cap the bag before sterilization to prevent bacteria from entering the bag after sterilization.

It is also possible to fill the bag with food contents, put a cap on and seal it, and then sterilize the sealed bag and the food contents at the same time. By irradiating with gamma rays, the packaging material and the food contents are sterilized at the same time, and the odor from the sealed bag can be reduced.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 An ethylene-vinyl acetate copolymer film (thickness 50μ) (vinyl acetate content 15%) was attached to the vinylidene chloride side of a vinylidene chloride coated stretched polyamide film (thickness 15μ) via a urethane adhesive and stretched on the other hand. Ethylene-butene-1 on the polyamide side
Copolymer film (thickness 50μ) (product name: Neozex,
(manufactured by Mitsui Petrochemicals) were bonded together using a urethane adhesive to create a laminated film. This film is processed into ethylene-butene-based bag using a regular sealed bag making machine.
The bag was made by sealing it on all sides so that the copolymer film was on the inside of the bag. Furthermore, the spout and cap were also molded from ethylene-butene-1 copolymer resin. The size of the bag was 300m/m x 300m/m and was used for 4 bags.

This bag was sterilized by irradiating it with 2.5 Mrad of γ-rays using a γ-ray irradiation device. Furthermore, this sterilized bag was aseptically filled with 4 sterilized skimmed emulsions (solid content 3%) using an aseptic filling machine (DN-AB machine, manufactured by Dainippon Printing Co., Ltd.).
This filling was carried out in 100 bags, which were then cultured at 37°C for 10 days, and the presence or absence of bacterial growth was observed. As a result, no bacteria were found in all 100 bags. In addition, this skim milk was taken out and subjected to a sensory test described below. In order to examine the physical properties of this bag, a filled sealed bag with a spout was placed in a predetermined cardboard box and dropped 7 times from a height of 1 m to check for leakage and damage to the bag, but no abnormalities were found.

Furthermore, when a vibration test was conducted at 1G for 30 minutes, no abnormalities were observed.

Comparative Example 1 A bag having the same specifications as in Example 1 was made, and four bags were filled with sterilized resin milk using the aseptic filling machine without irradiation with gamma rays. When this bag was cultured for 10 days at 37°C, the growth of bacteria was observed because the bag was not sterilized, so it was stored at low temperature at 5°C for 10 days and subjected to a sensory test.

The skimmed milk of Example 1 and Comparative Example 1 were compared using a three-point discrimination method. From a total of 3 samples, 2 samples of Comparative Example 1 and 1 sample of Example 1, one item that was felt to be different was selected. In this case, the probability of selecting the sample of Example 1 by chance is 1/3, but Example 1
Five out of the 15 panelists who selected the sample found no significant difference at all, and could not detect any odor caused by γ-ray irradiation.

Example 2 A 9μ aluminum foil and a 15μ stretched polyamide were bonded together using a urethane adhesive, and ethylene-4 was applied to the aluminum foil side and the stretched polyamide side, respectively.
-Methylpentene copolymer film (thickness 50μ)
A laminated film was made by bonding them together using a urethane adhesive. A double bag was made using a conventional bag-making machine with a sealed bag, with this film on the inside and an 80 μm ethylene-vinyl acetate copolymer film superimposed on the outside of this film.
Furthermore, this bag has an ethylene spout and a cap.
One molded from 4-methylpentene copolymer resin was used.

The size of the bag was 300m/m x 300m/m and was used for 4 bags. This bag was irradiated with 1.0 Mrad of γ-rays using a γ-ray irradiation device to sterilize mold and yeast. Furthermore, this sterilized bag was aseptically filled with four sterilized orange juices using an aseptic filling machine (DN-AB machine manufactured by Dai Nippon Printing Co., Ltd.). This filling was carried out in 100 bags, which were then cultured at 20°C for 20 days, and the presence or absence of mold and yeast growth was observed. As a result, no bacteria were found in all 100 bags. In order to check the physical properties of this bag, place the filled sealed bag with a cap in a designated cardboard box and hold it from a height of 1 m.
When the bag was dropped several times and the bag was checked for leakage and damage, no abnormalities were found. Further vibration test 1G30
No liquid leakage to the outside was observed when the test was carried out under conditions of 10 minutes. In addition, orange juice was taken out and subjected to the sensory test described below.

Comparative Example 2 A bag with the same specifications as in Example 2 was made and filled with four sterilized orange juices using the aseptic filling machine without irradiation with gamma rays. When this bag was cultured for 20 days at 20°C, the bag was not sterilized and bacteria were observed to grow, so it was stored at a low temperature at 5°C for 20 days and subjected to a sensory test.

A sensory test was conducted on the samples of Example 2 and Comparative Example 2 using the three-point discrimination method, but 6 out of 15 panelists selected the sample of Example 2, and no significant difference was observed at all. No odor was detected.

As detailed above, the sterile packaging bag of the present invention has the advantage of being rich in gas barrier properties and generating little odor during radiation sterilization.

[Brief explanation of drawings]

1 and 2 show a sterile packaging bag according to the present invention, FIG. 1 is a perspective view, and FIG. 2 is a perspective view of the bag shown in FIG.
It is a sectional view taken along the line A. 1...Polyolefin film, 2...Gas barrier film, 3...Ethylene and carbon number 3
Copolymer film of ~10 α-olefins, 4...
Laminated film.

Claims (1)

[Claims] 1 "Composite film consisting of an outer layer made of polyethylene, ethylene-4-methylpentene copolymer film or ethylene-vinyl acetate copolymer film, and a stretched film made of polyamide resin coated with vinylidene chloride resin, or aluminum foil" and a stretched polyamide film bonded together via a urethane adhesive, and an ethylene-butene-1 copolymer film, an ethylene-pentene-1 copolymer film, and an ethylene-hexene-1 copolymer film. A laminated film in which an inner layer consisting of a composite film, an ethylene-4-methylpentene copolymer film, or a linear low-density polyethylene film is adhered to each other with a urethane adhesive makes the inner layer surface of the laminated film a bag. 1. A sterile packaging bag characterized by comprising: a bag body formed so as to have an inner peripheral surface, and a spout and cap made of the same resin as the inner layer attached to the bag body.