JP2015016583A - Hollow container having deoxidation property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow container having a deoxidation property, which is restrained from being expanded when produced and has excellent external appearance.SOLUTION: The hollow container having the deoxidation property, at the least, has: an isolation layer (b layer) containing a thermoplastic resin β; an oxygen absorption layer (a layer) comprising a resin composition having the deoxidation property, which composition contains (I) an iron-based oxygen absorbent and (II) another thermoplastic resin α; and a gas barrier layer (c layer) in this order from the inside of the hollow container having the deoxidation property toward the outside thereof. The hollow container having the deoxidation property is molded by a direct blow method. The resin composition having the deoxidation property has 0.2 wt.% or lower water content.

Description

  The present invention relates to a deoxygenated molded container and a sealed container using the same, and can prevent oxidative deterioration of contents due to a decrease in gas barrier properties of a gas barrier layer due to high-temperature and high-humidity treatment such as boil and retort. The present invention relates to a container capable of keeping the quality of stored articles in good condition. The present invention relates to a hollow container having an improved gas barrier property and a hollow container capable of maintaining the inside of the container from a low oxygen state to an oxygen-free state without using a pouch-like oxygen absorber.

  One packaging technology that removes oxygen in the packaging container to store stuff to be packaged such as food and pharmaceuticals, and prevents oxidative degradation, discoloration, mold, aerobic bacterial growth, etc. As described above, a container is formed using an oxygen absorbing layer made of a deoxygenating resin composition in which an oxygen absorbent is blended with a thermoplastic resin to improve the gas barrier property of the container, and the container itself has an oxygen absorbing function. An oxygen container is used. A deoxygenating container is generally composed of four or more layers, an inner layer, an oxygen absorbing layer, a gas barrier layer, and an outer layer, and is formed into various shapes such as a tray, a pouch, a bottle, or a tube according to the purpose.

  As the deoxidizing container, for example, a container utilizing iron powder oxidation disclosed in Patent Document 1 can be used. Since iron powder is inexpensive and easy to handle as a deoxidizing material, it can be easily provided with deoxidizing performance by blending it into a thermoplastic resin and processing it into a sheet or film. Patent Document 2 discloses a technique in which a polyolefin layer is interposed between a deoxidant-containing resin layer and a gas barrier layer, Patent Document 3 discloses a vacuum forming technique for a deoxidizing multilayer body, and Patent Document 4 absorbs a high concentration of oxygen. A technique that uniformly disperses the agent and enables industrial continuous production is disclosed.

Japanese Patent No. 3682882 JP-A-8-132573 Japanese Patent No. 3838289 JP 2001-354817 A

  However, the present inventors have examined that when a deoxygenating resin composition in which an iron-based oxygen absorber is blended with a thermoplastic resin is used as a deoxygenating hollow container by direct blow molding, the iron-based oxygen absorber is used. It has been found that when the amount of water contained is large, there is a problem of foaming during the production of the hollow container.

  Moreover, the container using a deoxidation multilayer body provides an isolation layer between an oxygen absorption layer and the content so that an oxygen absorption layer and the content may not contact. However, the moisture contained in the deoxidizing resin composition is foamed by being exposed to a high temperature at the time of molding, and the separation layer is uneven and the appearance is deteriorated, or the separation layer has a hole and an iron-based oxygen absorbent. There was a risk that the contents would come into direct contact.

  An object of the present invention is to solve the above-mentioned problems of the deoxidizing hollow container in the prior art, and to provide a deoxygenating hollow container having a good appearance, in which foaming during production is suppressed.

  As a result of intensive studies in view of the above-described problems of the prior art, the present inventors have at least a separating layer (b layer) containing a thermoplastic resin β from the inside of the container toward the outside of the container, Direct blow having an oxygen absorption layer (a layer) made of a deoxygenating resin composition containing I) an iron-based oxygen absorbent and (II) a thermoplastic resin α, and a gas barrier layer (c layer) in this order. In the deoxygenated hollow container formed by the method, it was found that the above problem can be solved by setting the water content of the deoxygenated resin composition to 0.2% by weight or less, and the present invention has been completed. .

  According to the present invention, a deoxygenating hollow container having a good appearance and suppressing foaming during production is provided. In addition, improvement in product yield can be expected, which contributes to reduction of container costs.

  The container of the present invention comprises at least a separating layer (b layer) containing a thermoplastic resin β, (I) an iron-based oxygen absorbent, and (II) a thermoplastic resin α from the inside of the container toward the outside of the container. A deoxygenating hollow container formed by a direct blow method, having an oxygen absorbing layer (a layer) comprising a deoxygenating resin composition and a gas barrier layer (c layer) in this order, the oxygen absorbing layer The deoxidizing resin composition used for (a layer) is a deoxidizing hollow container characterized in that the moisture content of the deoxidizing resin composition before molding is 0.2% by weight or less.

[Iron-based oxygen absorber]
As the oxygen absorbent used in the present invention, all iron-based oxygen absorbents conventionally used for this type of application can be used. Examples of the iron powder include sprayed iron powder, sponge iron powder, electrolytic iron powder, Iron grinding powder, pulverized iron or the like is used, and iron powder having a low content of oxygen and silicon as impurities and a metal iron content of 95% by weight or more is particularly preferably used. Moreover, it is preferable to select the particle diameter of iron powder from the range of an average particle diameter of 1-100 micrometers. These promote the oxidation of alkali metals, alkaline earth metal hydroxides, carbonates, sulfites, thiosulfates, tertiary phosphates, secondary phosphates, organic acid salts, halides, etc. as required It can be used in combination with an agent or a catalyst.

  The iron-based oxygen absorbent used in the present invention may be a blend of reducing iron powder and the above-mentioned oxidation promoter or catalyst, but the core particles of the reducing iron powder and the oxidation promoter or catalyst coated thereon. It is more preferable to consist of these layers. Further, the oxidation promoter or catalyst should be present in an amount of 0.1 to 20.0% by weight, preferably 0.1 to 10.0% by weight, per reducing iron powder.

  Examples of the oxidation promoter or catalyst that coexists with the reducing iron powder include water-soluble or deliquescent inorganic electrolytes. Specific examples thereof include sodium chloride, calcium chloride, zinc chloride, ammonium chloride, sodium iodide, potassium iodide, ammonium sulfate, sodium sulfate, magnesium sulfate, disodium hydrogen phosphate, sodium diphosphate, potassium carbonate, sodium nitrate, etc. And inorganic salts.

[Deoxygenating resin composition]
The deoxidizing resin composition of the present invention can be obtained by blending the above-described iron-based oxygen absorbent into a resin. Mixing may be either melt blending or dry blending. When a small amount of oxygen absorbent is blended, it is preferable to prepare a masterbatch containing a high concentration of oxygen absorbent and mix this masterbatch with the resin. . Although it is not limited to this as resin which can mix | blend the oxygen absorbent of this invention, It can mix | blend with the thermoplastic resin conventionally used for the packaging material. Specifically, low-, medium- or high-density polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene- Propylene-butene-1 copolymer, polymethylpentene-1, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ion-crosslinked olefin copolymer (ionomer), ethylene-vinyl alcohol copolymer Olefin resins such as blends or blends thereof, styrene resins such as polystyrene, styrene-butadiene copolymer, styrene-isoprene copolymer, ABS resin, polyethylene terephthalate, polyethylene naphthalate, polytetramethylene terephthalate, glycol Modified polyethylene terephthalate DOO, polylactic acid, polyesters such as polybutylene succinate, nylon 6, can be incorporated into the polyamide and polycarbonate such as nylon 66.

  The water content of the deoxidizing resin composition of the present invention is 0.2% by weight or less, preferably 0.15% by weight or less, more preferably 0.1% by weight or less. By suppressing the water content of the deoxidizing resin composition, foaming can be suppressed, and poor appearance due to unevenness in the isolation layer and direct contact between the iron-based oxygen absorbent and the contents can be prevented.

  The blending amount of the oxygen absorbent of the present invention with respect to these resins is preferably in the range of 1 to 100 parts by weight, particularly 5 to 70 parts by weight per 100 parts by weight of the resin. When the amount of the oxygen absorbent is less than the above range, the expected oxygen absorption performance cannot be obtained. On the other hand, when it exceeds the above range, the formability and characteristics as a package may be deteriorated. There is.

  In the oxygen absorbing layer of the present invention, various additives such as a color pigment such as titanium oxide, an antioxidant, a slip agent, an antistatic agent and a stabilizer, clay, mica, silica, calcium carbonate, sulfuric acid are optionally added. Fillers such as calcium and barium sulfate, deodorizers, adsorbents such as activated carbon and zeolite, and the like may be added.

[Thermoplastic resin]
The resin constituting the inner and outer layers is not limited to this, but low-, medium- or high-density polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene -Butene-1 copolymer, ethylene-propylene-butene-1 copolymer, polymethylpentene-1, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ion-crosslinked olefin copolymer (Ionomers) Or olefin resins such as blends thereof, styrene resins such as polystyrene, styrene-butadiene copolymer, styrene-isoprene copolymer, ABS resin, polyethylene terephthalate, polyethylene naphthalate, polytetramethylene terephthalate , Glycol-modified polyethylene terf Mention may be made of polyesters such as tartrate, polylactic acid and polybutylene succinate, polyamides such as nylon 6 and nylon 66, polycarbonates and the like.

  In the lamination, an adhesive resin can be used, but is not limited thereto, but is not limited to ethylene-acrylic acid copolymer, ion-crosslinked olefin copolymer, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, acrylic acid grafted polyolefin. One or a combination of two or more of ethylene-vinyl acetate copolymer, copolymerized polyester, copolymerized polyamide and the like can be used.

  As the resin constituting the gas barrier layer, a gas barrier resin such as an ethylene-vinyl alcohol copolymer, nylon MXD6, or polyglycolic acid can be used.

  The deoxygenating resin composition of the present invention can be mixed and reused in the oxygen absorbing layer by appropriately mixing scraps and trim loss of the container.

  In the oxygen-absorbing laminate of the present invention, foods, pharmaceuticals 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 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 degradation of the article 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, retort treatment such as semi-retort, retort, and high retort at 100 ° C. to 135 ° C.

  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]
(Production of oxygen scavenger composition)
500 kg of reduced iron powder having an average particle size of 30 μm was put into a vacuum mixing dryer equipped with a heating jacket, sprayed with 5 kg of a 50 wt% calcium chloride aqueous solution while being heated at 110 ° C. under a reduced pressure of −720 mmHg, and dried for 2 hours. The coarser particle larger than 50 μm was removed by sieving to obtain an oxygen scavenger composition A having a maximum diameter of 50 μm.

(Manufacture of deoxygenating resin composition)
Next, using a vented 45 mmφ co-rotating twin screw extruder and a metering feeder, high-density polyethylene (melt index = 0.3 g / 10 min; 190 ° C.) having a melting point of 133 ° C. and the oxygen scavenger composition described above Was kneaded at a weight ratio of 50:50, extruded from a strand die, then air-cooled and crushed to obtain a deoxygenating resin composition A. At that time, a screen mesh of 100 mesh was installed on the breaker plate part of the twin screw extruder for the purpose of removing the aggregate of iron powder. When the moisture content of the deoxidizing resin composition A was measured with a Karl Fischer moisture meter at 185 ° C., the moisture content was 0.06%.

(Manufacture of oxygen-absorbing hollow containers)
Next, an oxygen-absorbing hollow container was obtained as follows. Oxygen-absorbing resin composition pellet A is used for the oxygen absorption layer (a layer), HDPE1 is used for the thermoplastic resin layer (b layer), and ethylene vinyl alcohol copolymer resin (Nippon Synthetic Co., Ltd.) is used as the gas barrier layer (c layer) resin. Chemical Industry Co., Ltd., trade name: Soarnol “DC3203RB”), and the resin of the adhesive resin layer (d) is carboxylic acid-modified polyolefin resin (Mitsubishi Chemical Corporation, trade name: Zelas “MC721AP”) used. A container with a capacity of 100 mL was prepared with a direct blow molding machine of 4 types and 6 layers. The dimensions were a height of 83.5 mm, a container bottom outer diameter of 48 mm, and a mouth inner diameter of 25.2 mm. The surface area of the innermost layer was 0.013 m2. The production temperature was 200 ° C. The layer structure of the oxygen-absorbing hollow container is from the outer surface to the inner surface, thermoplastic resin layer (b layer) / adhesive resin layer (d layer) / barrier layer (c layer) / adhesive resin layer (d layer) / Oxygen absorbing layer (a layer) / thermoplastic resin layer (b layer). The thickness of each layer was 600 μm / 100 μm / 100 μm / 100 μm / 100 μm / 200 μm / 100 μm from the outer surface to the inner surface.

  When the molded hollow container was observed, appearance defects such as irregularities were not seen in the isolation layer, and the molded state was good.

[Example 2]
In the production process of the oxygen scavenger composition, an oxygen scavenger composition was produced in the same manner as in Example 1 except that the drying time was changed from 2 hours to 1 hour. Thereafter, a deoxygenating resin composition and a hollow container were produced in the same manner as in Example 1. The water content of the obtained deoxygenating resin composition was 0.12%. When the molded hollow container was observed, as in Example 1, the isolation layer did not show any appearance defects such as irregularities, and the molded state was good.

[Comparative Example 1]
In the production process of the oxygen scavenger composition, an oxygen scavenger composition was produced in the same manner as in Example 1 except that the drying time was changed from 2 hours to 30 minutes. Thereafter, a deoxygenating resin composition and a hollow container were produced in the same manner as in Example 1. The water content of the obtained deoxidizing resin composition was 0.34%. When the molded hollow container was observed, irregularities were generated in the isolation layer, and exposure of the iron-based oxygen absorbent in the oxygen absorption layer was observed.

  As is clear from the above results, foaming is suppressed by setting the moisture content of the deoxidizing resin composition to 0.2% or less, and poor appearance due to irregularities in the isolation layer, and an iron-based oxygen absorbent Direct contact with the contents can be prevented.

Claims (4)

  From the inside of the container toward the outside of the container, at least a separating layer (b layer) containing a thermoplastic resin β, (I) an iron-based oxygen absorbent, and (II) a deoxygenating resin containing a thermoplastic resin α An oxygen-absorbing hollow container formed by a direct blow method, having an oxygen absorption layer (a layer) and a gas barrier layer (c layer) made of the composition in this order, the water content of the oxygen-absorbing resin composition A deoxidizing hollow container having a rate of 0.2% by weight or less.   2. The deoxygenating hollow container according to claim 1, wherein the iron-based oxygen absorbent is obtained by coating 0.1 to 10 parts by weight of a metal halide with respect to 100 parts by weight of iron powder.   The deoxygenating hollow container according to claim 1 or 2, wherein the metal halide is at least one selected from calcium chloride and sodium chloride.   The deoxidizing hollow container according to any one of claims 1 to 3, wherein a difference between the melt flow rate of the thermoplastic resin α and the melt flow rate of the thermoplastic resin β is 0 to 2 g / 10 minutes.