JP2001105540A - Oxygen absorbent multi-layer body and packaging container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen-absorbent multi-layer body and a packaging container which can keep the quality of an object to be preserved over a long period even under use conditions of a high temperature and high humidity, have no problem in irradiation and heating in a microwave oven, and are excellent in impact resistance. SOLUTION: In an oxygen absorbent multi-layer body composed of a heat seal layer of an oxygen permeable thermoplastic resin, an oxygen absorbent layer of a thermoplastic resin in which an iron oxygen absorbent is dispersed, and a gas-barrier layer, an impact resistant intermediate layer of an impact resistant thermoplastic resin is arranged between the oxygen absorbent layer and the gas-barrier layer, and the oxygen absorbent multi-layer body in which the gas-barrier layer is a silica-deposited film is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer body having an oxygen absorbing function, a packaging container, and a manufacturing method. For more information,
A silica-deposited surface of the silica-deposited film of the gas barrier layer,
Intermediate layer made of impact-resistant thermoplastic resin is provided between oxygen-absorbing layer surfaces of oxygen-absorbing layer in which iron-based oxygen absorbent is dispersed in thermoplastic resin. The present invention relates to an oxygen-absorbing multilayer body which has a long-term oxygen absorption performance without deterioration and can store food and medicine.

[0002]

2. Description of the Related Art In recent years, as one of the oxygen-absorbing packaging techniques, a container is formed of a multilayer material having an oxygen-absorbing layer made of an oxygen-absorbing resin composition obtained by blending an oxygen-absorbing agent with a thermoplastic resin.
A packaging container has been developed in which the gas barrier property of the container is improved and the container itself has an oxygen absorbing function.
Of these, an oxygen-absorbing multilayer body having a small total thickness, a so-called oxygen-absorbing multilayer film, is obtained by dispersing a deoxidizer as an intermediate layer in a conventional gas-barrier multilayer film in which a heat seal layer and a gas barrier layer are laminated. An oxygen-absorbing layer, which is a plastic resin layer, is laminated and used as a function of preventing oxygen permeation from the outside with a function of absorbing oxygen in the container, and is conventionally known as extrusion lamination, co-extrusion lamination, dry lamination, etc. It is manufactured using the manufacturing method described above. Specifically, Japanese Patent Application Laid-Open No. 9-40024
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-107, an oxygen-absorbing multilayer film in which a thermoplastic resin layer cushion layer is interposed between an oxygen-absorbing layer and a gas barrier layer is known. Also, JP-A-9-23
As disclosed in Japanese Patent No. 4832, an oxygen-absorbing multilayer film in which a smoothing layer is provided between an oxygen-absorbing layer and a gas barrier layer is known.

[0003]

[Problems to be Solved by the Invention] However, when metal foil or the like is used for the gas barrier layer, there is a problem that a microwave oven cannot be heated when foods and the like are stored, and a problem of incineration residue during incineration. are doing. When a barrier film made of a resin such as EVOH or nylon is used, the above problem can be solved. However, when a heat treatment such as a retort treatment or a boil treatment is performed, and when stored for a long period of time, oxygen to be transmitted from the outside may cause the object to be preserved. There is a problem that quality cannot be maintained well.

[0004] On the other hand, PET films and nylon films have a thickness of 300 to 7 as a resin barrier film exhibiting good oxygen barrier properties even after retort treatment or boil treatment.
There is a silica-deposited film provided with a silica-deposited film of 00 Å. When laminating a silica-deposited film, when lamination is performed by extrusion lamination with a molten resin, cracks occur in the silica-deposited film due to contact of the silica-deposited film with the resin melted at a high temperature, and the barrier property is significantly reduced. . Therefore, usually, when laminating a silica vapor-deposited film and another film, they are multilayered by dry lamination. However, when the silica-deposited layer is bonded to the oxygen-absorbing layer containing the iron-based oxygen absorbent by dry lamination, the silica-deposited film comes into contact with the iron powder, thereby causing cracks and the like in the silica-deposited film and impairing gas barrier properties. Had the problem that

An object of the present invention is to solve the above-mentioned problems, and it is possible to maintain the quality of the object to be preserved over a long period of time even under a high-temperature and high-humidity use condition, and to use a microwave oven. An object of the present invention is to provide an oxygen-absorbing multilayer body and a packaging container free from the problem of residue during irradiation or incineration.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems of the prior art, and as a result, have found that a gas barrier layer composed of a silica-deposited film and an iron-based oxygen absorbent are blended. Oxygen-absorbing multilayer body in which a thermoplastic resin intermediate layer is arranged between the layers, to find an oxygen-absorbing multilayer body that does not deteriorate the quality of the contents even when subjected to high-temperature treatment or heat sterilization by microwave or long-term storage. Was completed.

That is, the present invention provides, in order, a heat sealing layer made of a thermoplastic resin having oxygen permeability, an oxygen absorbing layer made of a resin composition in which an iron-based oxygen absorbent is dispersed in the thermoplastic resin, The present invention relates to an oxygen-absorbing multilayer body having a laminated structure of an impact-resistant intermediate layer made of a plastic resin and a gas barrier layer made of a vapor-deposited silica film. The present invention also relates to a packaging container in which part or all of the packaging container is formed of the above-described oxygen-absorbing multilayer body, and a method for storing articles using the same.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sealing layer constituting the oxygen-absorbing multilayer body of the present invention is a part that becomes a sealant when the oxygen-absorbing multilayer film of the present invention is used for part or all of a packaging container. In addition, it functions as an isolation layer that separates the stored articles from the oxygen absorbing layer, and as an oxygen permeable layer that efficiently transmits oxygen because oxygen in the packaging container is quickly absorbed by the oxygen scavenger in the oxygen absorbing layer. Has a role.

As the heat-sealing layer constituting the oxygen-absorbing multilayer film of the present invention, any thermoplastic resin having oxygen permeability that can fulfill the above-mentioned role can be used without limitation. . For example, various polyethylenes such as low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, metallocene-catalyzed polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-methyl acrylate copolymer, ethylene-acryl Ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer And various metallocene-catalyzed polypropylenes such as polypropylene, polymethylpentene, thermoplastic elastomers, etc., and these can be used alone or in combination.

In the heat seal layer, coloring pigments such as titanium oxide, additives such as antioxidants, slip agents, antistatic agents and stabilizers, fillers such as calcium carbonate, clay, mica and silica, deodorants, etc. May be added.

The thickness of the heat sealing layer constituting the oxygen-absorbing multilayer film of the present invention is preferably from 10 to 100 μm, more preferably from 20 to 60 μm.
If the thickness of the heat sealing layer is less than 10 μm, the oxygen absorbing agent of the oxygen absorbing layer is exposed on the surface and the heat sealing strength is undesirably reduced. On the other hand, when the thickness of the heat seal layer is more than 100 μm, it is not preferable because lamination becomes difficult, the oxygen permeability is reduced, the oxygen absorption performance of the film is reduced, and the cost is problematic.

The oxygen-absorbing layer constituting the oxygen-absorbing multilayer film of the present invention is formed by dispersing an oxygen scavenger in a thermoplastic resin. The oxygen absorbing layer has a role of absorbing oxygen dissolved in the container or the stored article, and a role of absorbing a small amount of oxygen entering from the outside of the barrier layer and preventing oxygen from permeating into the container.

As the thermoplastic resin constituting the oxygen absorbing layer of the present invention, the same resins as those mentioned above as the resin used for the heat seal layer are used, but in consideration of the compatibility with the heat seal layer. It is appropriately selected.

As the iron-based oxygen absorbent dispersed in the oxygen-absorbing layer constituting the oxygen-absorbing multilayer film of the present invention, a composition comprising iron powder and a metal halide is used. The iron powder as the main agent can be used without any particular limitation in purity and the like as long as it can cause an oxygen absorption reaction.For example, a part of the surface may be already oxidized, and contains other metals. You may do. The iron powder is preferably in the form of particles. For example, iron powder such as reduced iron powder, sprayed iron powder, electrolytic iron powder and the like, pulverized and ground products of various irons such as cast iron and steel are used. The average particle size is 1 to 10 in consideration of handleability, reducing the thickness of the oxygen absorbing layer, and minimizing unevenness of the oxygen scavenger appearing on the film appearance.
0 μm, preferably 1 to 80 μm
It is preferable to be within the range.

As the metal halide which is an auxiliary agent of the iron-based oxygen absorbent, for example, chloride, bromide or iodide of an alkali metal or alkaline earth metal is used, and lithium, sodium, potassium, magnesium, calcium or Barium chloride or iodide is preferably used. The compounding amount of the metal halide is preferably from 0.1 to 20 parts by weight, particularly preferably from 0.1 to 5 parts by weight, per 100 parts by weight of the iron powder.

The metal halide is preferably mixed and added in advance so that the metal halide adheres to the iron powder and is not easily separated. For example, a method of mixing a metal halide and iron powder using a ball mill, a speed mill, or the like, a method of embedding a metal halide in irregularities on the surface of the iron powder, a method of attaching a metal halide to the surface of the iron powder using a binder Alternatively, a method of mixing a metal halide aqueous solution and iron powder, drying the mixture, and then attaching the metal halide to the surface of the iron powder can be employed. The preferred oxygen absorbent is an iron powder-based composition containing iron powder and a metal halide, and particularly preferably a metal halide-coated iron powder-based composition in which a metal halide is attached to iron powder.

The amount of the oxygen scavenger in the oxygen absorbing layer constituting the oxygen absorbing multilayer film of the present invention is from 10 to 70.
% By weight, preferably 10 to 60% by weight.
Is more preferable. 10% by weight of oxygen absorber
If it is lower, the oxygen absorbing ability is insufficient, which is not preferable. If it is higher than 70% by weight, it is difficult to form an oxygen absorbing layer, which is not preferable.

The thickness of the oxygen-absorbing layer constituting the oxygen-absorbing multilayer film of the present invention is 20 to 10 regardless of the constituent materials.
It is preferably in the range of 0 μm, particularly preferably 3 μm.
The range is from 0 to 80 μm. The thickness of the oxygen absorbing layer is 20μ
When the thickness is smaller than m, film formation becomes difficult, or the amount of the oxygen scavenger per unit area of the film decreases, so that sufficient oxygen absorption performance cannot be obtained. On the other hand, when the thickness is more than 100 μm, the total thickness of the film becomes large, which may cause inconvenience in handling properties and cause a problem in cost.

The oxygen-absorbing layer of the present invention may contain, if necessary, a coloring pigment such as titanium oxide, various additives such as an antioxidant, a slip agent, an antistatic agent, a stabilizer, clay, mica, and silica. And fillers such as calcium carbonate, calcium sulfate and barium sulfate, deodorants, and adsorbents such as activated carbon and zeolite.

In the present invention, a silica vapor-deposited film is preferably used for the gas barrier layer. Silica (silica oxide, S) is deposited on a polyethylene terephthalate film or nylon film as a base film.
iOx) is 100-1 by physical vapor deposition or chemical vapor deposition.
It is a film deposited to a thickness of 000 angstroms. The value of x of silicon oxide SiOx to be deposited is preferably 1.5 to 1.8 from the viewpoint of gas barrier properties. The silica-deposited film does not decrease in oxygen barrier property even when exposed to high temperature and high humidity, and has an oxygen permeability of 2 cc /
Those having m ² · day · atm or less are preferred.

In the present invention, an impact-resistant intermediate layer made of an impact-resistant thermoplastic resin is disposed between the oxygen-absorbing layer and the silica-deposited film. When a silica-deposited film and an oxygen-absorbing layer are laminated by dry lamination without an impact-resistant intermediate layer, the silica-deposited surface and the oxygen-absorbing layer containing the iron-based oxygen absorbent are in direct contact, and the silica-deposited surface is in the oxygen-absorbing layer. Cracks often occur due to contact with iron powder. When cracks occur on the silica-deposited surface, the oxygen barrier properties are significantly reduced, and the quality of foods and pharmaceuticals cannot be maintained well. By providing an intermediate layer made of a thermoplastic resin between the oxygen-absorbing layer and the silica-deposited film serving as a gas barrier layer, it is possible to suppress the occurrence of cracks in the silica-deposited film and maintain good gas barrier properties.

In the present invention, as the resin used for the impact-resistant intermediate layer provided between the oxygen absorbing layer and the gas barrier layer, a thermoplastic resin having excellent impact resistance is used. Specifically, various polyester resins such as polyethylene terephthalate and polybutylene terephthalate, various polyamide resins such as nylon 6, nylon 6, 6 and the like, or a combination thereof are used. Among them, a polyamide resin is preferably used because the strength of the oxygen-absorbing multilayer body increases. The resin used for the impact-resistant intermediate layer can be colored with a coloring agent or printed to cover the oxygen absorbing layer.

The heat-sealing layer of the present invention comprising a thermoplastic resin having oxygen permeability, an oxygen-absorbing layer comprising a resin composition in which an iron-based oxygen absorbent is dispersed in a thermoplastic resin, and an impact-resistant thermoplastic resin. An oxygen-absorbing packaging container can be manufactured by partially or entirely using an oxygen-absorbing multilayer body having a laminated structure of an impact-resistant intermediate layer and a gas barrier layer formed of a silica-deposited film. After the article is sealed in the oxygen-absorbing packaging container, and preferably subjected to a heat treatment and stored, the article can be stored for a long period of time while maintaining the quality.

Packaging containers using the oxygen-absorbing multilayer film of the present invention include, for example, liquid beverages such as milk, juice, sake, whiskey, shochu, coffee, tea, jelly beverages, health beverages, seasonings, sauces, and soy sauce. , Dressing, liquid stock, seasonings such as mayonnaise, miso, grated spices, pasty foods such as jam, cream, chocolate paste, liquid soups, boiled foods, pickled vegetables, liquid processed foods such as stewed liquids Ya, soba, udon,
Raw noodles such as ramen and boiled noodles, rice before cooking such as polished rice, moisture-conditioned rice, unwashed rice, cooked cooked rice, processed rice products such as gomeshi, red rice, rice porridge, powdered soup, soup stock High-moisture foods represented by powder seasonings, etc., other solid and solution chemicals such as pesticides and insecticides, liquid and paste pharmaceuticals, lotions, cosmetic creams, cosmetic emulsions, hair dyes, hair dyes It can store various items such as hair, shampoo, soap, detergent, etc., and oxygen does not enter from outside the container,
Further, since oxygen inside the container is absorbed by the oxygen scavenger composition, oxidative corrosion of the article is prevented, and good quality can be maintained for a long period of time.

[0025]

Examples of the present invention will be described below. Note that the present invention is not limited to these examples.

Example 1 An aqueous solution containing 3 parts by weight of calcium chloride was mixed with 100 parts by weight of reduced iron powder having an average particle diameter of 30 μm and dried to obtain a granular coated iron powder-based oxygen scavenger composition. . 30 parts by weight of the obtained oxygen scavenger composition, 69 parts by weight of ethylene-propylene random copolymer resin (trade name: F8090, manufactured by Chisso Corporation) and 1 part by weight of calcium oxide were blended, and the mixture was mixed with a 35 mm twin screw extruder. The mixture was extruded, cooled with a net belt with a blower, and then passed through a pelletizer to obtain a compound containing an oxygen absorbent.

A 50 μm-thick unstretched polypropylene film (trade name, manufactured by Tocelo Co., Ltd.) which is fed out on the inner surface side using an extrusion laminating apparatus comprising a single screw extruder, a T-die, a cooling roll, a slitter and a winding machine. RXC-1
1) was used as a sealant layer, and the oxygen-absorbing agent-containing compound prepared above was extruded and laminated at a thickness of 30 μm to form an oxygen-absorbing layer. Further, a stretched nylon film having a thickness of 15 μm printed thereon as an intermediate layer is dry-laminated with the printed surface on the outer side so that the printed surface does not come into contact with the oxygen-absorbing layer.
A 2 μm silica-deposited polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corp. Pax Co., Ltd., trade name: Tech Barrier T) was dry-laminated and laminated such that the silica-deposited surface was on the inner side to form an oxygen barrier layer. The obtained multilayer film has a composition of polypropylene / oxygen absorbent-containing compound // stretched nylon / printing // silica vapor-deposited film / PET from the inner side, and its impact strength at 5 ° C. is 12.6 kg · cm. Met.

Next, the obtained oxygen-absorbing multilayer film 1
Then, a four-sided sealed bag having an inner size of 18 cm × 15 cm was prepared, filled with 200 cc of beef stew, and 100 bags were sealed by heat sealing so that the space inside the bag was about 5 cc. This package was subjected to a heat treatment at 125 ° C. for 30 minutes, and then at 35 ° C. and 80% RH.
After storing for 1 month in a constant temperature and humidity chamber,
All the bags were heated by microwave irradiation in a 500 W microwave oven for 2 minutes, and then opened to investigate the odor and color tone of the stew. All of the 100 bags had good flavor and color tone.

Example 2 The resin used in the compound containing an oxygen absorbent used in Example 1 was LLDPE (Kernel KC580S, manufactured by Nippon Polychem Co., Ltd.), and the film fed out on the inner surface side was LLDPE having a thickness of 50 μm. Example except that the film was made by Higashi Sero Co., Ltd. (trade name: HC)
An oxygen-absorbing multilayer film 2 was obtained in the same manner as in 1. The obtained oxygen-absorbing multilayer film 2 is LLDPE
/ Compound containing oxygen absorber // stretched nylon / printing // deposited silica film / PET, and its impact strength at 5 ° C. was 13.1 kg · cm. Next, the inner dimensions 1 cut out from the obtained oxygen-absorbing multilayer film 2
A self-supporting bag was prepared using two side films of 8 cm × 15 cm and a bottom film cut out from a barrier film without an oxygen absorbing layer (LLDPE // stretched nylon / printing // silica-deposited film / PET). Corn soup 2
The bag was filled with 00 cc, and sealed by heat sealing so that the space in the bag became about 5 cc. 100 bags of this package are 9
After a heat treatment at 5 ° C. for 30 minutes,
The sample was stored in a thermo-hygrostat at 50 ° C. and 50% RH for one month. All the stored 100 bags were heated by microwave irradiation in a 500 W microwave oven for 2 minutes, and then opened to investigate the odor and color tone of the soup. All of the 100 bags had good flavor and color tone.

[Comparative Example 1] In Example 1, the arrangement of the stretched nylon film and the silica-deposited film of the oxygen-absorbing multilayer film 1 was reversed, and the polypropylene /
Oxygen absorbent containing compound // Silica vapor deposition film / PET
/ Printing // Oxygen-absorbing multilayer film 3 composed of stretched nylon. Its impact strength at 5 ° C is 1
It was 1.8 kg · cm. The same storage test as in Example 1 was performed using the oxygen-absorbing multilayer film 3. as a result,
Oxidizing odor was felt in 27 bags out of 100 bags, and fading of the soup was recognized. It is considered that this is because the silica-deposited surface was cracked due to contact with iron powder in the oxygen absorbing layer, the oxygen barrier property was reduced, and the deoxidized state could not be maintained.

[Comparative Example 2] In Example 2, the arrangement of the stretched nylon film and the silica-deposited film of the oxygen-absorbing multilayer film 2 was reversed, and LLDPE / oxygen-absorbent-containing compound // silica-deposited film / PET from the inner side. / Printing // Oxygen-absorbing multilayer film 4 made of stretched nylon was obtained. The impact strength at 5 ° C. was 12.1 kg · cm. The same storage test as in Example 2 was performed using the oxygen-absorbing multilayer film 4. Oxidizing odor was felt in 16 bags out of 100 bags, and fading of the soup was recognized. This was thought to be because the silica-deposited surface was cracked due to contact with the iron powder in the oxygen absorbing layer, the oxygen barrier property was reduced, and the deoxidized state could not be maintained.

Comparative Example 3 In Example 2, an LLDPE film having a thickness of 15 μm was used in place of the stretched nylon film, and LLDPE / oxygen absorbent-containing compound // LLDPE / printing // silica vapor-deposited film from the inner surface side An oxygen-absorbing multilayer film 5 having a structure of / PET was obtained. The impact strength at 5 ° C. was 6.8 kg · cm, which was lower than that of the multilayer film prepared in Example 2.

[0033]

As described above, the oxygen-absorbing multilayer film of the present invention comprises an oxygen-absorbing intermediate layer made of an impact-resistant thermoplastic resin between a silica vapor-deposited layer and an oxygen-absorbing layer constituting a gas barrier layer. Cracks do not occur in the vapor-deposited silica-deposited film, maintain good barrier properties, and it is possible to keep the quality of the object to be preserved over a long period of time even under high-temperature, high-humidity use conditions, and a microwave oven. It is an oxygen-absorbing multilayer body excellent in impact resistance without any problem in irradiation or heating. The packaging container comprising the oxygen-absorbing multilayer body of the present invention retains its initial appearance and flavor even when stored for a long period of time, various foods,
Enables long-term storage of stored items such as pharmaceuticals.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Sotaro Hiramatsu 5-6-1 Higashi-Hachiman, Hiratsuka-shi, Kanagawa F term in Sanritsu Gas Chemical Co., Ltd. Hiratsuka Research Laboratory 3E067 AA03 AA04 AB01 AB19 AB20 AB21 AB26 AB27 AB28 AB81 AB96 BB14A BB15A BB16A BB22A BB25A CA04 CA24 EE25 EE32 EE48 GB13 GC02 GC04 GD01 4F100 AA20D AB02B AK01A AK01B AK01C AK41C JAK42 AK46C AK48 AR00D BA04 E10B16JD16 J16 BA10 BAB EBAD

Claims (4)

[Claims] 1. A heat-sealing layer made of a thermoplastic resin having oxygen permeability, an oxygen-absorbing layer made of a resin composition in which an iron-based oxygen absorbent is dispersed in a thermoplastic resin, and an impact-resistant thermoplastic resin. An oxygen-absorbing multilayer body having a laminated structure of an impact-resistant intermediate layer and a gas barrier layer composed of a vapor-deposited silica film. 2. The oxygen-absorbing multilayer body according to claim 1, wherein the impact-resistant intermediate layer is made of a polyester resin, a polyamide resin or a combination thereof. 3. An oxygen-absorbing packaging container comprising the oxygen-absorbing multilayer body according to claim 1, wherein part or all of the packaging container. 4. A method for preserving an article, comprising sealing the article in the oxygen-absorbing packaging container according to claim 3 and then subjecting the article to heat treatment.