JP2008126441A - Oxygen absorbing multilayer film and packaging container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an oxygen-absorbing multilayer film by extrusion lamination which prevents sticking of an oxygen-absorbing layer to a cooling roll and does not cause defective dry lamination due to slip agent bleeding.
In order from the inner surface side, at least, a sealant layer made of a thermoplastic resin, an oxygen absorption layer made of a resin composition in which an iron-based oxygen absorbent is dispersed in the thermoplastic resin, and a barrier layer made of a gas barrier material are provided. In the oxygen-absorbing multilayer film, the oxygen-absorbing multilayer film is characterized in that the thermoplastic resin of the oxygen-absorbing layer is polyolefin, and the oxygen-absorbing layer contains 0.08 to 0.25% by weight of a slip agent.
[Selection figure] None

Description

  In order from the inner surface side, at least an oxygen-absorbing multilayer comprising a sealant layer made of a thermoplastic resin, an oxygen-absorbing layer made of a resin composition in which an iron-based oxygen absorbent is dispersed in the thermoplastic resin, and a barrier layer made of a gas barrier substance. In the film, the oxygen-absorbing multilayer film is characterized in that the thermoplastic resin of the oxygen-absorbing layer is a polyolefin, and the oxygen-absorbing layer contains 0.08 to 0.25% by weight of a slip agent. The present invention also relates to an oxygen-absorbing packaging container comprising the oxygen-absorbing multilayer film of the present invention.

  As a method for improving the storage stability of food and preventing changes in flavor, there is a packaging technique using an oxygen scavenger, which is used in various foods. The oxygen scavenger packaging technology is a technology that prevents deterioration of food quality due to the presence of oxygen by keeping the inside of the packaging container enclosing the food to be stored in an anaerobic state using an oxygen scavenger. In recent years, as one of the deoxygenation packaging technologies, a container is composed of a multilayer material in which an oxygen-absorbing layer made of an oxygen-absorbing resin composition in which an oxygen absorbent is blended with a thermoplastic resin, thereby improving the gas barrier properties of the container. At the same time, development of packaging containers in which the container itself is provided with an oxygen absorbing function has been underway.

Among these, an oxygen-absorbing multilayer having a small total thickness, a so-called oxygen-absorbing multilayer film, is a multilayer film comprising a sealant layer, an oxygen-absorbing layer that is a thermoplastic resin layer in which an oxygen-absorbing agent is dispersed, and a gas barrier layer. It is used as a function to prevent oxygen permeation from the outside of the container and a function to absorb oxygen in the container, and is manufactured using a conventionally known manufacturing method such as extrusion lamination, co-extrusion lamination, and dry lamination. Has been. Specifically, as disclosed in JP-A-9-40024, 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. Further, as disclosed in JP-A-9-234832, an oxygen-absorbing multilayer film in which a smoothing layer is provided between an oxygen-absorbing layer and a gas barrier layer is known.
Japanese Patent Laid-Open No. 9-40024 Japanese Patent Laid-Open No. 9-234832

  However, when producing an oxygen-absorbing multilayer film in which an oxygen-absorbing layer composed of a resin composition in which an iron-based oxygen absorbent is dispersed in a sealant layer and a thermoplastic resin layer, a resin composition composed of a polyolefin resin is simply used. When extruded on one side of the sealant layer using an extrusion laminating machine consisting of a shaft extruder, T-die, and cooling roll, slipping of the oxygen absorbing layer surface is insufficient and sticking to the cooling roll occurs, resulting in an oxygen absorbing multilayer film. There was a problem that wrinkles and tarmi occurred.

  On the other hand, when a slip agent is blended in the oxygen absorbing layer made of polyolefin resin, the slipping property of the oxygen absorbing layer surface can be improved and sticking to the cooling roll can be prevented, and the generation of wrinkles and talmi in the oxygen absorbing multilayer film can be prevented. However, there is a problem that bleeding of the slip agent occurs from the oxygen absorbing layer, the wettability of the surface of the oxygen absorbing layer is lowered, and dry lamination failure occurs.

  As a result of intensive studies to solve the problems of the oxygen scavenger packaging technology, the present inventors have found that a slip agent is added to an oxygen absorbing resin composition in which an iron powder-based oxygen absorber is kneaded and dispersed in a polyolefin resin. By adding 0.08 to 0.25% by weight of oxygen, when an oxygen-absorbing multilayer film made by laminating a sealant layer and an oxygen-absorbing layer is produced by extrusion lamination, the oxygen-absorbing layer is prevented from sticking to the cooling roll. In addition, the present inventors have found that a dry lamination failure due to slip agent bleed does not occur and completed the present invention.

  That is, in order from the inner surface side, at least an oxygen provided with a sealant layer made of a thermoplastic resin, an oxygen absorption layer made of a resin composition in which an iron-based oxygen absorbent is dispersed in the thermoplastic resin, and a barrier layer made of a gas barrier material. The present invention relates to an oxygen-absorbing multilayer film characterized in that the thermoplastic resin of the oxygen-absorbing layer is a polyolefin, and the oxygen-absorbing layer contains 0.08 to 0.25% by weight of a slip agent. The present invention also relates to an oxygen-absorbing packaging container comprising the oxygen-absorbing multilayer film of the present invention.

The oxygen-absorbing multilayer film of the present invention contains 0.08 to 0.25% by weight of a slip agent in the oxygen absorbent resin, so that the oxygen absorbent layer does not stick to the cooling roll and the workability is It is an excellent oxygen-absorbing multilayer film that can prevent generation of wrinkles and tarmi in the oxygen-absorbing multilayer film, and has no problem of poor dry lamination due to slip agent bleeding.
The packaging container comprising the oxygen-absorbing multilayer film of the present invention retains the initial appearance and flavor even when stored for a long period of time, and enables long-term storage of stored articles such as various foods and pharmaceuticals.

  The sealant layer constituting the oxygen-absorbing multilayer film of the present invention is a part that becomes a sealant when the oxygen-absorbing multilayer film of the present invention is used for a part or all of a packaging container, and the stored article and the oxygen-absorbing layer It has a role as an isolation layer that isolates oxygen and a role as an oxygen permeable layer that efficiently transmits oxygen because oxygen in the packaging container is quickly absorbed by the oxygen absorbent in the oxygen absorption layer.

  The sealant layer constituting the oxygen-absorbing multilayer film of the present invention can be used without limitation as long as it is an oxygen-permeable thermoplastic resin that can play the aforementioned role. For example, various polyethylenes such as low density polyethylene, linear low density polyethylene, ultra low density polyethylene, polyethylene by metallocene catalyst, ethylene-vinyl acetate copolymer, ionomer, ethylene-methyl acrylate copolymer, ethylene-acrylic Ethyl acid 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 polypropylenes such as polypropylene by a metallocene catalyst, polymethylpentene, thermoplastic elastomer and the like, and these can be used alone or in combination.

  Among these, in particular, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, various polyethylenes such as polyethylene by metallocene catalyst, propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer Polypropylenes such as coalescence are preferred.

  Colorant pigments such as titanium oxide, additives such as antioxidants, slip agents, antistatic agents, stabilizers, fillers such as calcium carbonate, clay, mica and silica, deodorizers, etc. are added to the sealant layer. Also good.

  The film thickness of the sealant layer constituting the oxygen-absorbing multilayer film of the present invention is preferably 10 to 100 μm, and more preferably 20 to 80 μm. If the thickness of the sealant layer is less than 10 μm, the oxygen absorbent in the oxygen absorbing layer is exposed on the surface or the heat seal strength is lowered, which is not preferable. On the other hand, when the film thickness of the sealant layer is larger than 100 μm, it is not preferable because lamination becomes difficult, oxygen permeability is lowered and oxygen absorption performance of the film is lowered, and there is a problem in cost.

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

  As the thermoplastic resin constituting the oxygen-absorbing layer of the present invention, for example, various polyethylenes such as low density polyethylene, linear low density polyethylene, ultra-low density polyethylene, and polyethylene by metallocene catalyst can be used alone or in combination. . Also, ethylene-vinyl acetate copolymer, ionomer, ethylene-methyl acrylate copolymer, ethylene-methyl acrylate copolymer, propylene polymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer, metallocene catalyst It can also be used in combination with various polypropylenes such as polypropylene, polymethylpentene, thermoplastic elastomer and the like.

  As the oxygen absorber dispersed in the oxygen absorbing layer constituting the oxygen-absorbing multilayer film of the present invention, an iron-based oxygen absorber composition composed of iron powder and a metal halide is preferably used. The iron powder that is the main component of the iron-based oxygen absorbent composition can be used without any particular limitation on the purity, etc., as long as it can cause an oxygen absorption reaction. For example, a part of the surface is already oxidized. Or may contain other metals. The iron powder is preferably granular, and for example, iron powder such as reduced iron powder, sprayed iron powder, and electrolytic iron powder, pulverized products of various iron such as cast iron and steel, and ground products are used. The average particle size is preferably in the range of 1 to 100 μm in consideration of handling properties, reducing the thickness of the oxygen absorbing layer, and minimizing the unevenness of the oxygen absorbent appearing in the film appearance. In particular, the range of 1 to 80 μm is preferable.

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

  It is preferable that the metal halide is mixed and added in advance so as not to adhere to the iron powder and easily separate. For example, a method of mixing a metal halide and iron powder using a ball mill, a speed mill, etc., a method of embedding a metal halide in the uneven portion of the iron powder surface, a method of attaching a metal halide to the iron powder surface using a binder A method of adhering a metal halide to the surface of the iron powder by drying after mixing the aqueous metal halide solution and the iron powder can be employed. A preferable oxygen absorbent is an iron powder-based composition containing iron powder and a metal halide, and particularly preferably a metal halide-coated iron powder composition in which a metal halide is attached to the iron powder.

  The amount of the oxygen absorbent in the oxygen-absorbing layer constituting the oxygen-absorbing multilayer film of the present invention is preferably in the range of 10 to 70% by weight, more preferably in the range of 10 to 60% by weight. If the blending amount of the oxygen absorbent is lower than 10% by weight, the oxygen absorbing ability is insufficient and is not preferable. If it is higher than 70% by weight, it is difficult to form an oxygen absorbing layer, which is not preferable.

  In the present invention, a polyolefin resin in which an oxygen absorbent is dispersed and a slip agent is added is used as the oxygen absorbing layer. The slip agent is an additive for reducing the resistance of the surface of the oxygen absorbing layer to improve slipperiness and improve processability, and fatty acid amide lubricants, fatty acid lubricants, and fatty acid metal soaps are preferably used. Fatty acid amide type lubricants such as erucic acid amide, palmitic acid amide and stearic acid amide are particularly preferred. The amount of slip agent added in the oxygen-absorbing layer constituting the oxygen-absorbing multilayer film of the present invention is preferably in the range of 0.08 to 0.25% by weight, and in the range of 0.10 to 0.20% by weight. Is more preferable. If the blending amount of the slip agent is lower than 0.08% by weight, the slipping property of the surface of the oxygen absorbing layer is not sufficient and sticking to the cooling roll is not preferable. If it is higher than 0.25% by weight, the slip agent bleeds. This is not preferable because the wettability of the surface of the oxygen absorbing layer is lowered and a dry lamination defect occurs.

  The method for adding the slip agent in the present invention is not limited, and the polyolefin resin and the slip agent may be mixed and kneaded in advance, or the polyolefin resin to which the slip agent has been added may be used. Moreover, you may use a slip agent masterbatch.

  The film thickness of the oxygen-absorbing layer constituting the oxygen-absorbing multilayer film of the present invention is preferably in the range of 20 to 100 μm, particularly preferably in the range of 30 to 80 μm, regardless of the constituent materials. If the film thickness of the oxygen absorbing layer is thinner than 20 μm, film formation becomes difficult, or the amount of oxygen absorbent per unit area of the film decreases, and sufficient oxygen absorbing performance cannot be obtained. On the other hand, if it is thicker than 100 μm, the total thickness of the film is increased, which may cause inconvenience in handling and a problem in cost.

  In addition, the oxygen absorbing layer of the present invention may contain various additives such as color pigments such as titanium oxide, antioxidants, antistatic agents, stabilizers, clay, mica, silica, calcium carbonate, calcium sulfate, if necessary. Further, a filler such as barium sulfate, a deodorant, an adsorbent such as activated carbon or zeolite, and the like may be added.

  In the present invention, the gas barrier layer is a layer that blocks oxygen entering from the outside of the container when it is used as a packaging container. For example, metal foil such as aluminum foil, polyvinylidene chloride, saponified ethylene-vinyl acetate copolymer Nylon 6, nylon 6,6, nylon MXD6, gas barrier resin such as polyethylene terephthalate, vapor deposition film such as aluminum vapor deposition film, alumina vapor deposition film, silica vapor deposition film, etc. can be used alone or in combination.

  The oxygen-absorbing multilayer film of the present invention comprises, in order, at least three layers: a sealant layer made of a thermoplastic resin, an oxygen absorption layer in which an oxygen absorbent and a slip agent are blended with a polyolefin resin, and a barrier layer made of a gas barrier material. However, other layers can be added.

  For example, in order to prevent damage to the gas barrier layer and pinholes, it is preferable to provide a protective layer made of a thermoplastic resin outside the barrier layer. Examples of the resin used for the protective layer include polyethylenes such as high density polyethylene, polypropylenes such as propylene homopolymer, propylene-ethylene random copolymer, propylene-ethylene block copolymer, nylon 6, nylon 6,6 and the like. Polyamides, polyesters such as polyethylene terephthalate, and combinations thereof.

  The oxygen-absorbing multilayer film of the present invention can be used as an oxygen-absorbing container composed entirely of the oxygen-absorbing multilayer film, but has a gas barrier property such as a container composed of one side of the oxygen-absorbing multilayer film and one side of a general gas barrier film. It can also be used as an oxygen-absorbing container in which the oxygen-absorbing multilayer film is used in a part of the container.

  In the sealed container of the present invention, food, medicines and the like are stored without limitation. For example, jelly with pulp, confectionery such as sheep crab, pudding, pine, oranges, peaches, apricots, none, fruits such as apples, liquid soup, seasonings such as mayonnaise, miso, grated spices, jam, cream, chocolate Pasty foods such as paste, liquid foods represented by liquid processed foods such as curry, liquid soup, boiled food, pickles, stew, raw noodles such as buckwheat, udon, ramen and boiled noodles, polished rice, conditioned rice, Pre-cooked rice such as non-washed rice, cooked cooked rice, processed rice products such as gomoku rice, red rice and rice bran, high-moisture foods represented by powder seasonings such as powdered soup and dashi nomoto Stores various articles such as solid and solution chemicals such as agricultural chemicals and insecticides, liquid and paste pharmaceuticals, lotion, cosmetic cream, cosmetic milk, hair conditioner, hair dye, shampoo, soap, detergent, etc. To do Oxygen does not enter from the outside of the container, and oxygen inside the container is absorbed by the oxygen scavenger composition, preventing oxidative corrosion of articles and maintaining good quality over a long period of time. It becomes.

  Moreover, you may heat-process the sealed container of this invention. Examples of the heat treatment include boil treatment at 80 ° C. to 100 ° C., boiling treatment, semi-retort treatment at 100 ° C. to 121 ° C., retort treatment, and the like. Furthermore, the sealed container of the present invention can be heated in a microwave oven.

  Articles to which the method of the present invention is applied are not necessarily limited to the above-mentioned foods, cereals, pharmaceuticals, etc., as long as they can achieve the initial purpose by applying the method of the present invention. Good.

The present invention will be described in more detail with reference to examples. In addition, this invention is not necessarily limited to an Example.
Example 1
1000 kg of iron powder with an average particle size of 30 μm is put into a vacuum dryer equipped with a heating jacket, mixed with 140 kg at a reduced pressure of 10 mmHg at 140 ° C., sprayed with 50 kg of 50% by weight aqueous solution of calcium chloride, dried, sieved, and coarsened An iron-based oxygen absorbent having an average particle size of 30 μm was obtained except for the grains.
Next, using a twin-screw extruder with a vent, iron-based oxygen is produced by side feed while extruding a slip agent composed of linear low density polyethylene (manufactured by Dow Chemical Co., Ltd., trade name PT1450) and erucic acid amide. Supplying an absorbent and calcium oxide, kneading so that polyethylene: iron-based oxygen absorbent: calcium oxide: slip agent = 67.85: 30.00: 2.00: 0.15 weight ratio, and strand die Then, the mixture was cooled and pelletized with a pelletizer to obtain an oxygen-absorbing resin composition A.

  Using an extrusion laminating machine consisting of a single-screw extruder, T-die, cooling roll, slitter and winder, a 50 μm-thick LLDPE film (made by Tosero Co., Ltd., trade name HC) is used as a sealant layer on the inner surface side. Then, the oxygen-absorbing resin composition A produced thereon was extruded and laminated with a thickness of 30 μm to obtain an oxygen-absorbing layer. The oxygen absorbing layer did not stick to the cooling roll, the workability was good, and the oxygen absorbing multilayer film was not wrinkled or sagged.

  Further, a 15 μm-thick stretched nylon film is dry laminated as an intermediate layer thereon, and further, a 12 μm-thick silica-deposited polyethylene terephthalate film (trade name: Techbarrier T, manufactured by Mitsubishi Chemical Kojin Pax Co., Ltd.) Were laminated and laminated to form an oxygen barrier layer. The obtained multilayer film was composed of LLDPE // oxygen absorbing layer // nylon // silica vapor deposited PET from the inner surface side, and the dry laminate between the oxygen absorbing layer and nylon was good.

  The sealant layer surfaces of the oxygen-absorbing multilayer film were heat-sealed to produce a 150 mm × 200 mm three-side sealed oxygen-absorbing bag. A mixture of mandarin orange 100 g and syrup solution 100 g was sealed in the produced bag, heated at 95 ° C. for 40 minutes, and stored at 25 ° C. On the 30th day of storage, the color and flavor of mandarin oranges were evaluated. As a result, the color and flavor of the mandarin orange were well maintained.

Example 2
The addition amount of the slip agent used in Example 1 was changed, except that polyethylene: iron-based oxygen absorbent: calcium oxide: slip agent = 67.80: 30.00: 2.00: 0.20 weight ratio. In the same manner as in Example 1, an oxygen-absorbing resin composition B was obtained.
Further, the oxygen-absorbing resin composition was the same as in Example 1 except that polyethylene: iron-based oxygen absorbent: calcium oxide: slip agent = 67.90: 30.00: 2.00: 0.10 weight ratio. Product C was obtained.

Extrusion lamination was performed in the same manner as in Example 1 using the oxygen-absorbing resin compositions B and C. B and C also did not cause sticking of the oxygen absorbing layer to the cooling roll, had good workability, and did not cause wrinkles or sagging in the oxygen absorbing multilayer film.
The oxygen-absorbing multilayer film obtained in the same manner as in Example 1 is composed of LLDPE // oxygen-absorbing layer // nylon // silica-deposited PET from the inner surface side, and B and C are the oxygen-absorbing layer and nylon. The dry laminate strength was strong, and the dry laminate was good.

Example 3
Extrusion lamination was performed in the same manner as in Example 1 except that the sealant film used in Example 1 was an LLDPE film having a thickness of 80 μm (trade name HC, manufactured by Tosero Co., Ltd.). The oxygen absorbing layer did not stick to the cooling roll, the workability was good, and the oxygen absorbing multilayer film was not wrinkled or sagged. Further, the oxygen-absorbing multilayer film obtained in the same manner as in Example 1 has a structure of LLDPE // oxygen-absorbing layer // nylon // silica-deposited PET from the inner surface side, and a dry laminate between the oxygen-absorbing layer and nylon. The strength was strong and the dry laminate was good.

Comparative Example 1
The addition amount of the slip agent used in Example 1 was changed, except that polyethylene: iron-based oxygen absorbent: calcium oxide: slip agent = 67.93: 30.00: 2.00: 0.07 weight ratio. In the same manner as in Example 1, an oxygen-absorbing resin composition D was obtained.

  Extrusion lamination was performed in the same manner as in Example 1 using the oxygen-absorbing resin composition D. Sticking of the oxygen absorbing layer to the cooling roll occurred, the workability was poor, and wrinkles and sagging occurred in the oxygen absorbing multilayer film.

Comparative Example 2
An anti-blocking agent (trade name ABT16, manufactured by Tokyo Ink Co., Ltd.) was added to the composition of Comparative Example 1, and polyethylene: iron-based oxygen absorbent: calcium oxide: slip agent: anti-blocking agent = 62.93: 30.00 : Oxygen-absorbing resin composition E was obtained in the same manner as in Example 1, except that the weight ratio was 2.00: 0.07: 5.00.

  Using the oxygen-absorbing resin composition E, extrusion lamination was carried out in the same manner as in Example 1. Sticking of the oxygen absorbing layer to the cooling roll occurred, the workability was poor, and wrinkles and sagging occurred in the oxygen absorbing multilayer film.

Comparative Example 3
The addition amount of the slip agent used in Example 1 was changed, except that polyethylene: iron-based oxygen absorbent: calcium oxide: slip agent = 67.74: 30.00: 2.00: 0.26 weight ratio. In the same manner as in Example 1, an oxygen-absorbing resin composition F was obtained.

  Using the oxygen-absorbing resin composition F, extrusion lamination was carried out in the same manner as in Example 1. The oxygen absorbing layer did not stick to the cooling roll, the workability was good, and the oxygen absorbing multilayer film was not wrinkled or sagged.

  The oxygen-absorbing multilayer film obtained in the same manner as in Example 1 has a structure of LLDPE // oxygen-absorbing layer // nylon // silica-deposited PET from the inner surface side, and a dry laminate between the oxygen-absorbing layer and nylon. The strength was low and the dry laminate was poor.

Claims (3)

In order from the inner surface side, at least an oxygen-absorbing multilayer comprising a sealant layer made of a thermoplastic resin, an oxygen-absorbing layer made of a resin composition in which an iron-based oxygen absorbent is dispersed in the thermoplastic resin, and a barrier layer made of a gas barrier substance. In the film, the oxygen-absorbing multilayer film is characterized in that the thermoplastic resin of the oxygen-absorbing layer is polyolefin, and the oxygen-absorbing layer contains 0.08 to 0.25% by weight of a slip agent. 2. The oxygen-absorbing multilayer film according to claim 1, wherein the polyolefin is polyethylene. An oxygen-absorbing packaging container comprising a part or all of the packaging container comprising the oxygen-absorbing multilayer film according to claim 1.