JP2000211080A - Oxygen absorbable multilayered film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen absorbable multilayered film excellent in impact resistance on both sides thereof and also excellent in linear tear properties. SOLUTION: In an oxygen absorbable multilayered film consisting of at least an oxygen permeable layer, an oxygen absorbing layer, an intermediate layer, a gas barrier layer and a protective layer all of which are successively laminated, the intermediate layer comprises a stretched polyamide resin. When a packaging bag comprising this oxygen absorbable multilayered film is packed with food or medicines to be hermetically sealed and preserved, the generation of burst or a pinhole is prevented even if the packaging bag receives an impact from the outside or inside thereof and, at a time of opening, the packaging bag can be linearly torn and is sanitary and good in handling properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen-absorbing multilayer film excellent in impact resistance from both the outside and the inside of the multilayer film. Also, the present invention relates to an oxygen-absorbing multilayer film having good linear tearability. The oxygen-absorbing multilayer film of the present invention can be used as a packaging container for food or medicine.

[0002]

2. Description of the Related Art In recent years, as one of the oxygen-absorbing packaging techniques, a package is made of a multilayer material in which an oxygen-absorbing resin composition containing an oxygen-absorbing composition is arranged to improve the gas barrier properties of a container. At the same time, a package having a package container provided with a deoxidizing function is being developed. A package having a deoxidizing function usually has an oxygen absorbing layer composed of an oxygen absorbing resin layer containing an oxygen absorbing composition as an intermediate layer, and has a gas barrier layer having a gas barrier property and oxygen permeability on both sides thereof. It is composed of an oxygen-absorbing multilayer body having an oxygen-permeable layer, and a sheet-like or film-like oxygen-absorbing multilayer body is a multilayer resin laminate structure that can be easily formed into a packaging container such as a bag, a cup, or a tray. It has been developed as

Conventionally, a deoxidizing multilayer film is composed of an oxygen-permeable layer made of an oxygen-permeable thermoplastic resin, an oxygen-absorbing layer made of an oxygen-absorbing resin composition obtained by mixing a deoxidizing composition with a thermoplastic resin, and polyethylene. , An adhesive layer made of a polyolefin such as polypropylene, a gas barrier layer made of a gas barrier resin, and a protective layer, each of which is basically laminated.

For example, Japanese Patent Application Laid-Open No. 2-56547 discloses a packaging material comprising an oxygen-permeable resin layer, an adhesive layer, an oxygen-absorbing sheet, an adhesive layer and an oxygen-permeable sheet. As an adhesive used for lamination,
A polyolefin-based thermoplastic resin hot-melt adhesive such as polyethylene resin and polypropylene resin is described. Also, JP-A-8-132573 and JP-A-9-400
No. 24 describes an oxygen absorbing laminate comprising a sealant layer, a resin layer having an oxygen absorbing function, a polyolefin layer, and a gas barrier layer. However, the conventional oxygen-absorbing multilayer film has a packaging bag in which the oxygen-permeable layers face each other, and is filled with solid contents such as frozen foods and pharmaceuticals. As a result, the contents may break through from the inside of the packaging bag, causing breakage or pinholes. Further, in order to enhance the impact resistance, it is known to use a polyamide resin for the gas barrier layer or the protective layer.In this method, impact resistance from the outside of the package is obtained, but from the inside of the packaging bag. There is a problem that the impact resistance is slightly inferior.

Further, when a conventional oxygen-absorbing multilayer film is made into a packaging bag so that the oxygen-permeable layers face each other, and the contents are filled and sealed, the film does not tear linearly upon opening, and the contents are not torn. Occasionally, the oxygen absorbing layer may be spilled, and a whisker-like debris may be generated, resulting in poor appearance.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a pinhole of a packaging bag due to the protrusion of contents, leakage of contents at the time of opening, and oxygen absorption without appearance defects. It is to provide a multilayer film. The present invention provides an oxygen-absorbing multilayer film having excellent impact resistance from both the inside and outside of the oxygen-absorbing multilayer film and having good tearability.

[0007]

Means for Solving the Problems At least an oxygen permeable layer,
In an oxygen-absorbing multilayer film comprising an oxygen-absorbing layer, an intermediate layer, a gas barrier layer, and a protective layer, each of which is sequentially laminated, an oxygen-absorbing multilayer film characterized in that the intermediate layer is made of a polyamide resin is used. Further, the above-mentioned oxygen-absorbing multilayer film, which is a polyamide resin obtained by stretching a polyamide resin, is used.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The configuration of the oxygen-absorbing multilayer film (may be abbreviated as a multilayer film) of the present invention includes at least an oxygen-permeable layer,
It has a laminated structure of an oxygen absorbing layer, an intermediate layer, a gas barrier layer and a protective layer. Further layers can be added to each layer of the multilayer film as needed. Further, when a special treatment such as deposition of aluminum oxide or silicon oxide or coating of polyvinylidene chloride is performed on the protective layer, the protective layer may also serve as a gas barrier layer.

The function of each layer when the multilayer film of the present invention is used to form a packaging bag will be described. The oxygen permeable layer serves as an isolation layer for preventing direct contact between the oxygen absorbing layer and the contents of the packaging bag. The role of quickly and efficiently permeating oxygen in the container so that the layer can sufficiently exert its oxygen absorbing function, and when sealing as a packaging bag, the oxygen-permeable layers of the multilayer film and other barrier multilayer films Plays the role of heat sealing surface. The oxygen absorption layer cannot be completely blocked by the gas barrier layer, and of course not only oxygen that penetrates,
It plays a role in absorbing oxygen in the container. The gas barrier layer serves to prevent oxygen from entering from outside.

The resins used for the oxygen permeable layer are polyolefins such as polyethylene, polypropylene and polymethylpentene, polystyrenes such as polystyrene, and modified products thereof, copolymers of various ethylenes such as EVA, EMMA, EAA, and elastomers. And the like, and polyethylene and polypropylenes are particularly preferred.

For the oxygen absorbing layer, an oxygen absorbing resin composition obtained by mixing a deoxidizer with a thermoplastic resin is used. As the oxygen scavenger, an oxygen scavenger composition containing iron powder as a main component and a metal halide as an oxygen absorption promoter is preferably used. As the iron powder, for example, spray iron powder, sea surface iron powder, electrolytic iron powder, iron grinding powder, crushed iron, etc. are used. The content of oxygen and silicon as impurities is small, and the metal iron content is 95% by weight or more. Iron powder is particularly preferably used. The metal halide is preferably an alkali metal or alkaline earth metal chloride, bromide or iodide. In the present invention, an iron powder coated with an alkyl metal halide or an alkyl earth metal halide prepared by mixing an aqueous metal halide solution with iron powder and then drying to remove water is preferably used. The particle size of the oxygen scavenger is preferably from 1 to 200 μm, more preferably from 5 to 150 μm. The content of the oxygen absorber in the oxygen-absorbing resin composition is preferably from 10 to 50% by weight, more preferably from 15 to 40% by weight.

The thermoplastic resin used for the oxygen absorbing layer includes polyolefins such as polyethylene, polypropylene, and polymethylpentene; polystyrenes such as polystyrene;
And modified products thereof, various ethylene copolymers such as EVA, EMMA and EAA, and thermoplastic resins such as elastomers, and polyethylene and polypropylene are particularly preferable. These resins are used singly or in an appropriate blend. In the oxygen absorbing layer, various additives such as a water absorbing agent such as an alkaline earth metal oxide, a deodorant such as activated carbon and zeolite, a white inorganic filler such as calcium sulfate, barium sulfate, and aluminum oxide, and a pigment such as titanium oxide. Can be added.

The intermediate layer is made of nylon-6, nylon-
6, 6, and polyamide resins such as nylon MXD6 are used. The use of the polyamide resin in the intermediate layer results in an oxygen-absorbing multilayer film having excellent impact resistance from the oxygen permeable layer side and the gas barrier layer side of the multilayer film. For the intermediate layer, a stretched polyamide resin is preferably used. By using a stretched polyamide resin for the intermediate layer, the oxygen-absorbing multilayer film not only has excellent impact resistance from the oxygen-permeable layer side and the protective layer side of the multilayer film, but also has excellent linear tearability. become. The stretching ratio is 1.1 times in both the vertical and horizontal directions.
It is preferably 4.0 times, more preferably 3.0 times to 3.5 times.

For the gas barrier layer, metal foil such as aluminum foil, ethylene-vinyl alcohol copolymer, nylon MXD
6, a gas barrier resin film of polyester or the like, a vapor-deposited resin film obtained by vapor-depositing aluminum oxide or silicon oxide, or the like is used alone or in combination. Of these, gas barrier resin films or vapor-deposited resin films other than metal foils are used for the gas barrier layer in order to seal and store foods and the like to make a microwave oven packaging bag for microwave cooking with the package. Is preferred. It is preferable to laminate a protective layer as the outermost layer outside the gas barrier layer. As a gas barrier layer, when a film having a heat-resistant film such as a polyester film or a polyamide film, a barrier film obtained by evaporating aluminum oxide or silicon oxide, or a film subjected to a treatment such as coating with polyvinylidene chloride is used. The film can serve as both a gas barrier layer and a protective layer.

As the resin used for the protective layer, high-density polyethylene for polyethylenes, propylene homopolymer, propylene-ethylene random copolymer, propylene-ethylene block copolymer for polypropylenes, and nylon 6, nylon 6, for polyamides. 6, and
Polyethylene terephthalate; Of these, polyamide or polyethylene terephthalate is preferably used.

The oxygen-absorbing multilayer film of the present invention uses a polyamide resin stretched for the intermediate layer, so that the packaging bag is prepared with the oxygen-permeable layer inside and the content such as food or medicine is filled and sealed. It has excellent impact resistance and piercing resistance from both sides of the film, so there is no pinhole due to piercing of the contents, and because it has excellent linear tearing property when opening, it has leakage due to contents and mustache caused by oxygen absorption layer It is a hygienic and easy-to-handle oxygen-absorbing multilayer film free from poor appearance such as dust.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples. Note that the present invention is not necessarily limited to the embodiments. Example 1 100 parts by weight of reduced iron powder having an average particle diameter of 30 μm was put into a vacuum air dryer with a heating jacket,
After heating at 140 ° C. under reduced pressure of not more than mmHg and spraying and drying 5 parts by weight of a 50% by weight aqueous solution of calcium chloride,
Sieving to remove coarse particles over 80 µm, maximum diameter 8
0 μm calcium chloride-coated iron powder was obtained. 0.3 parts by weight of calcium sulfate having an average particle size of 30 μm was mixed with 100 parts by weight of the obtained coated iron powder by a tumbler to obtain an oxygen scavenger composition. Next, using a venting 45 mmΦ co-rotating twin-screw extruder and an extruder consisting of a fixed-quantity feeder,
Melting point 153 ° C, melt flow rate 22g / 10min (J
IS K7210; 230 ° C 2.16 kgf) propylene-ethylene random copolymer (trade name: Chissopolypro F8090, manufactured by Chisso Corporation) and the oxygen scavenger composition are kneaded at a weight ratio of 75:25, After being extruded from a strand die, the mixture was air-cooled and crushed to obtain a master batch A comprising an oxygen-absorbing resin composition.

Next, using a tandem extrusion laminator having an extruder consisting of a single screw extruder, a T die, and a cooling roll, a non-stretched film made of a propylene-ethylene block copolymer fed out and having a thickness of 50 μm and a melting point of 167 ° C. (Trade name: RX-11, manufactured by Tosello Co., Ltd.)
The masterbatch A was extruded and laminated with a thickness of 30 μm from an extruder to obtain a laminated film composed of an oxygen-permeable layer / oxygen-absorbing layer.

On the oxygen-absorbing layer side of the obtained laminated film,
A nylon-6 film having a thickness of 15 μm as an intermediate layer, an aluminum foil having a thickness of 9 μm as a gas barrier layer, and a polyethylene terephthalate film having a thickness of 12 μm as a protective layer are sequentially dry-laminated to form an oxygen-permeable layer / oxygen-absorbing layer / intermediate layer / An oxygen-absorbing multilayer film comprising a gas barrier layer / protective layer was obtained. When the impact resistance (JIS P8134) at 5 ° C. of the obtained oxygen-absorbing multilayer film was measured, it was 15 kg on both the oxygen-permeable layer side and the protective layer side.

This oxygen-absorbing multilayer film is 15 cm ×
Cut two pieces to 15cm, heat-sealing the three sides with the oxygen-permeable layers made of unstretched polypropylene facing each other, filling 150g of baby food, sealing with heat-sealing, oxygen-absorbing multilayer on both sides A packaging bag made of a film was produced.

Further, the packaging bag in which the baby food was sealed was subjected to a heat treatment at 121 ° C. for 30 minutes. After the treatment, the packaging bag was opened for tearing, so that it could be torn in a straight line, no whisker-like debris due to the oxygen absorbing layer was observed, and it was confirmed that there was no problem in tearing properties.

Comparative Example 1 Master Batch A of Example 1
The test was carried out in the same manner as in Example 1 until the point was obtained. Then, using a tandem extrusion laminator having two sets of extruders consisting of a single screw extruder, a T die, and a cooling roll, one side of an unstretched film having a thickness of 30 μm and a melting point of 167 ° C. made of a propylene-ethylene block copolymer fed out. Then, the master batch A was extruded and laminated at a thickness of 30 μm from a first extruder, and a propylene-ethylene block copolymer having a melting point of 167 ° C. was extruded and laminated at a thickness of 50 μm from a second extruder. A multilayer film consisting of an oxygen absorbing layer / intermediate layer was obtained.

An aluminum foil of 9 μm thickness, a nylon 6 film of 9 μm thickness and a polyethylene terephthalate film of 12 μm thickness are sequentially dry-laminated on the oxygen absorption layer of the obtained multilayer film to form an oxygen permeable layer / oxygen absorption layer. / Intermediate layer / gas barrier layer / protective layer to obtain an oxygen-absorbing multilayer film. When the impact resistance (JIS P8134) at 5 ° C. of the obtained oxygen-absorbing multilayer film was measured, the oxygen-permeable layer side was 10 kg and the protective layer side was 15 kg.
A decrease was observed in Kg and the impact resistance from the oxygen permeable layer side.

This oxygen-absorbing multilayer film is 15 cm ×
Cut two pieces to 15cm, heat-sealing the three sides with the oxygen-permeable layers made of unstretched polypropylene facing each other, filling 150g of baby food, sealing with heat-sealing, oxygen-absorbing multilayer on both sides A packaging bag made of a film was produced.

Further, the packaging bag in which the baby food was sealed was heated at 121 ° C. for 30 minutes. After the treatment, to open the packaging bag, when tearing, whisker-like debris caused by the oxygen absorbing layer occurs, and also not tear straight,
The contents were about to spill.

Example 2 In Example 1, the master batch A was used.
The propylene-ethylene random copolymer used for the preparation was melted at a melting point of 109 ° C. and a melt flow rate of 9.0 g / 10.
Min (JIS K6750; 190 ° C, 2.16 kgf)
Low density polyethylene (trade name: NUC polyethylene 8)
009, manufactured by Nippon Unicar Co., Ltd.) to obtain a master batch B in the same manner as in Example 1.

Next, using a tandem extrusion laminator having two sets of extruders consisting of a single-screw extruder, a T-die, and a cooling roll, the first extrusion was performed on one surface of a 40 μm thick linear low-density polyethylene film to be fed. 8. Extruding and laminating the masterbatch B to a thickness of 30 μm from the extruder, and then, from the second extruder, melt flow rate.
0 g / 10 minutes (190 ° C, 2,16 kgf, JIS K
6750) low-density polyethylene (trade name: NUC polyethylene 8009, manufactured by Nippon Unicar Co., Ltd.) with a thickness of 20 μm, and from the other side, stretched nylon-6 having a thickness of 15 μm / aluminum foil having a thickness of 9 μm / thickness A three-layer laminated film made of polyethylene terephthalate having a thickness of 12 μm was wound and sandwich lamination was performed to obtain an oxygen-absorbing multilayer film composed of an oxygen-permeable layer / oxygen-absorbing layer / intermediate layer / gas barrier layer / protective layer. Impact resistance of the obtained oxygen-absorbing multilayer film at 5 ° C. (JIS P813
When 4) was measured, 1 was obtained for both the oxygen permeable layer side and the protective layer side.
It was 3 kg.

This oxygen-absorbing multilayer film is 15 cm ×
Cut two pieces to 15 cm, bond the oxygen permeable layers made of linear low-density polyethylene to each other, heat-join three sides, fill 150 g of baby food, seal with heat seal, seal both sides with oxygen A packaging bag made of the absorbent multilayer film was produced.

Further, the packaging bag in which the baby food was sealed was heated at 90 ° C. for 30 minutes. After the treatment, the packaging bag was opened for tearing, so that the packaging bag could be torn linearly. Further, it was confirmed that there was no problem with no whisker-like debris caused by the oxygen absorbing layer.

Comparative Example 2 Master Batch B of Example 2
The test was performed in the same manner as in Example 2 until the point was obtained.
Then, using a tandem extrusion laminator having two sets of extruders consisting of a single-screw extruder, a T-die, and a cooling roll, the thickness of the linear low-density polyethylene fed out is 30
The masterbatch B was extruded and laminated at a thickness of 30 μm from a first extruder on one side of a μm film, and a low-density polyethylene (trade name: NUC)
Polyethylene 8009, manufactured by Nippon Unicar Co., Ltd.) 50
It was extruded and laminated with a thickness of μm to obtain a multilayer film composed of an oxygen-permeable layer / oxygen-absorbing layer / intermediate layer.

The resulting oxygen-absorbing layer of the multilayer film was sequentially dry-laminated with an aluminum foil having a thickness of 9 μm, a nylon-6 film having a thickness of 9 μm and a polyethylene terephthalate film having a thickness of 12 μm. / Intermediate layer / gas barrier layer / protective layer to obtain an oxygen-absorbing multilayer film. When the impact resistance (JIS P8134) at 5 ° C. of the obtained oxygen-absorbing multilayer film was measured, the oxygen-permeable layer side was 8 kg, and the protective layer side was 12 k.
g and the impact strength from the oxygen permeable layer side were reduced.

This oxygen-absorbing multilayer film is 15 cm ×
Cut two pieces to 15 cm, bond the oxygen permeable layers made of linear low-density polyethylene to each other, heat-join three sides, fill 150 g of baby food, seal with heat seal, seal both sides with oxygen A packaging bag made of the absorbent multilayer film was produced. Further, the packaging bag in which the baby food was sealed was subjected to a heat treatment at 121 ° C. for 30 minutes. After the treatment, the packaging bag was opened for tearing. When the packaging bag was torn, a whisker-like debris caused by the oxygen absorbing layer was generated. Further, the package was not torn linearly and the contents were almost spilled.

Example 3 A test was conducted in the same manner as in Example 1 until a laminated film composed of the oxygen-permeable layer / oxygen-absorbing layer of Example 1 was obtained. On the oxygen-absorbing layer side of the obtained laminated film, a film in which stretched nylon 6 and stretched MXD6 are laminated (trade name: nylon super neal, thickness 1)
5 μm, manufactured by Mitsubishi Chemical Corporation) by dry lamination so that the stretched nylon 6 and the oxygen absorbing layer are in contact with each other, and further dry-laminated a printed polyethylene terephthalate film having a thickness of 12 μm to obtain an oxygen permeable layer / oxygen absorbing layer / intermediate layer. An oxygen-absorbing multilayer film consisting of a gas barrier layer and a protective layer was obtained. The resulting oxygen-absorbing multilayer film was measured for impact resistance at 5 ° C. (JIS P8134), and found to be 19 kg on both the oxygen-permeable layer side and the protective layer side.

This oxygen-absorbing multilayer film is 15 cm ×
Two pieces of 15 cm were cut out, the oxygen-permeable layers made of unstretched polypropylene were opposed to each other, three sides were joined by heat sealing, and 150 g of spaghetti meat sauce was filled.
The package was sealed by heat sealing to prepare a packaging bag made of an oxygen-absorbing multilayer film on both sides.

Further, the packaging bag in which the spaghetti meat sauce was sealed was subjected to a heating treatment at 121 ° C. for 30 minutes, and then stored at 23 ° C. After two months, to open the packaging bag, where torn, you can tear straight,
In addition, no whisker-like debris due to the oxygen absorbing layer is seen,
It was confirmed that there was no problem with tearing. Then, it was cooked in a microwave oven as it was, and it was confirmed that the flavor was good.

Example 4 A test was performed in the same manner as in Example 1 until a laminated film composed of the oxygen-permeable layer / oxygen-absorbing layer of Example 1 was obtained. On the oxygen-absorbing layer side of the obtained laminated film, printed stretched nylon 6 was laminated by dry lamination, and further, silica-deposited polyethylene terephthalate film (trade name: Tech Barrier T,
Dry-laminated 12 μm thick, manufactured by Mitsubishi Kojin Pax Co., Ltd.) to obtain an oxygen-absorbing multilayer film comprising an oxygen-permeable layer / oxygen-absorbing layer / intermediate layer / gas barrier layer and protective layer. When the impact resistance (JIS P8134) at 5 ° C. of the obtained oxygen-absorbing multilayer film was measured, it was 18 kg on both the oxygen-permeable layer side and the protective layer side.

This oxygen-absorbing multilayer film is 15 cm ×
Cut two pieces to 15 cm, make the oxygen-permeable layers made of unstretched polypropylene face each other, join them on three sides by heat sealing, fill 150 g of the base of Chinese seasoning vinegar pork, and seal by heat sealing, A packaging bag composed of an oxygen-absorbing multilayer film on both sides was prepared.

Further, the packaging bag in which the base of the Chinese seasoning seasoning pork was sealed was heat-treated at 121 ° C. for 30 minutes, and then stored at 23 ° C. After two months, to open the packaging bag, where torn, you can tear straight,
In addition, no whisker-like debris due to the oxygen absorbing layer is seen,
It was confirmed that there was no problem with tearing. Then, it was cooked in a microwave oven as it was, and it was confirmed that the flavor was good.

[0039]

The oxygen-absorbing multilayer film of the present invention is used as a material for packaging containers for foods or medicines, and receives an impact from the outside or inside of the container during transportation or handling such as heat treatment. Even in this case, the occurrence of bag breakage and pinholes is prevented, and the packaging bag is hygienic and easy to handle. In addition, when the stretched polyamide resin is used for the intermediate layer, it has excellent linear tearability when opened, so that there is no appearance defect such as leakage of contents and whisker-like debris caused by the oxygen absorbing layer, and the packaging bag Excellent linear tearability when opening.

Continued on the front page F-term (reference) 4F100 AA09H AB02H AB10 AB33 AK42 AK46C AK48 AK64 AR00A AR00B AR00D AS00E BA05 BA07 BA10A BA10E CA09 DE01H EJ37C GB16 GB23 GB66 JD02D JD03A JD14B JK10 JK05 JL01

Claims (2)

[Claims] 1. An oxygen-absorbing multilayer film comprising an oxygen-permeable layer, an oxygen-absorbing layer, an intermediate layer, a gas barrier layer and a protective layer, wherein each layer is sequentially laminated, wherein the intermediate layer comprises a polyamide resin. Absorbent multilayer film. 2. The oxygen-absorbing multilayer film according to claim 1, wherein the polyamide resin is a stretched polyamide resin.