WO2001048064A1

WO2001048064A1 - Method for drying and storage of oxygen-scavenging resin or oxygen-scavenging packaging material

Info

Publication number: WO2001048064A1
Application number: PCT/JP1999/007316
Authority: WO
Inventors: Yuki Miyazawa; Yoshihiro Kobayashi; Toru Ikeda; Shigenobu Harano; Masao Yamane
Original assignee: Ajinomoto Co., Inc.
Priority date: 1999-12-27
Filing date: 1999-12-27
Publication date: 2001-07-05

Abstract

A method for the drying and storage of an oxygen-scavenging resin or an oxygen-scavenging packaging material, characterized in that an oxygen-scavenging resin containing an oxygen-scavenging agent comprising iron powder and a metal halide salt, an oxygen-scavenging packaging material manufactured by laminating the oxygen-scavenging resin and another material or an oxygen-scavenging container fabricated by using the oxygen-scavenging packaging material is subjected to a heat treatment at a temperature which is 20°C or more higher than the crystal water release temperature of the metal halide salt, which is a temperature at which the crystal water of the metal halide salt is released to form a substantially anhydrous salt, and then the rein, the packaging material or the container is stored in a sealed state together with a drying agent having an absorptivity for moisture substantially equal to or more than that of the anhydrous salt of the metal halide salt in a packaging container having moisture barrier properties. This method allows preventing with ease the oxygen-scavenging ability of the above oxygen-scavenging resin, oxygen-scavenging packaging material or oxygen-scavenging container from lowering during the storage thereof and easily preventing them from foaming when subjected to heat forming or heat sealing.

Description

Description Dry storage method of deoxidizing resin or deoxidizing packaging material

(Technical field)

The present invention relates to a method for drying and preserving an oxygen-absorbing resin or an oxygen-absorbing packaging material. Oxygen-absorbing resin, oxygen-absorbing packaging material made by laminating this oxygen-absorbing resin with another material, or oxygen-absorbing container made by processing this oxygen-absorbing packaging material. Collectively, in this specification, it may be collectively referred to as "deoxidized packaging material").

(Background technology)

The composition of the oxygen absorbent is disclosed in Japanese Patent Publication No. 53-141185, which discloses a combination of reduced iron (main agent) and an oxidation promoter such as calcium chloride. On the other hand, some calcium chlorides have water of crystallization, and the existence of hexahydrate, tetrahydrate, dihydrate and monohydrate is known. It has been confirmed from the absorption curve of the differential thermal analysis that the water of crystallization is desorbed by heating and becomes an anhydrous salt (anhydrous) at 200 ° C. according to the present inventors. Calcium chloride is also used as a desiccant, and it is known that not only anhydrous salts but also dihydrates have hygroscopicity.

On the other hand, in the past, an oxygen-absorbing agent-containing resin layer in which an oxygen-absorbing agent (oxygen-absorbing agent) was dispersed in resin was used for a part of films, sheets, containers, etc. ) Is proposed in Japanese Patent Publication No. 6-32 348, Japanese Patent Publication No. 62-1842, and Japanese Patent Publication No. 6-57319. However, these prior arts have a slow oxygen absorption rate and a high oxygen absorption capacity. And there was a major problem that a practical deoxygenation function could not be obtained.

After that, the oxygen-absorbing performance of the resin containing oxygen scavenger was improved by mixing and dispersing calcium chloride as an oxidation promoter in addition to the reduced iron as the main agent as the oxygen scavenger. However, in order to take advantage of the hygroscopicity of calcium chloride, a resin containing an oxygen-absorbing agent in which it is blended and dispersed, a packaging material containing an oxygen-absorbing agent, and a packaging material containing the oxygen-absorbing agent prepared using the resin are processed. Although the containers containing oxygen absorbers prepared in this way have improved their own hygroscopicity and, consequently, improved their oxygen absorbing function, they have problems with hygroscopicity during storage of them and the secondary problems associated with them. This has led to the problem of preventing moisture absorption.

In other words, in the case of a resin containing a deoxidizing agent in which a deoxidizing agent containing, for example, calcium chloride as an oxidation promoter is dispersed in a polyolefin resin, it is difficult to completely remove water present in the resin. Simply taking measures to seal in a steam barrier container (storage bag), such as a metal foil laminate bag, will gradually absorb the oxygen in the headspace in the bag during the storage period, resulting in a decrease in deoxygenation capacity. Occurred. Further, when the amount of water in the oxygen-absorbing agent-containing resin increases, a problem arises that foaming occurs when the resin is thermoformed into a film-containing oxygen-absorbing agent-containing packaging material. Similarly, in the case of a packaging material containing an oxygen scavenger prepared using such a resin containing an oxygen scavenger and a container including the oxygen scavenger produced by processing the packaging material including the oxygen scavenger, the storage period is also the same. The deoxygenation ability was reduced during storage, and foaming occurred when the stored packaging material was thermoformed into a container or when the content of the stored container was filled and heat sealed. A so-called self-reactive reaction method in which the minimum amount of water necessary for the start of deoxygenation is retained in a storage bag so that it works even in low-moisture environments. A resin containing an oxygen scavenger, which is stored by removing oxygen in the head space, enclosed with the oxygen scavenger sachet, made using this resin It is conceivable to maintain the oxygen-absorbing ability (oxygen absorption performance) of the oxygen-absorbing agent-containing packaging material and the oxygen-absorbing agent-containing container made using this packaging material. Certainly, if the oxygen scavenger sachet is enclosed, the oxygen in the head space is completely removed and the oxygen scavenging ability can be maintained, but on the other hand, the water contained in the oxygen scavenger sachet deoxygenates It migrates to resin-containing resin, etc., which causes foaming during thermoforming after storage. As mentioned above, even though packaging materials with deoxygenation performance reaching the practical range have been developed, no storage method suitable for maintaining their performance and performing stable thermoforming has been found at present. It is.

(Disclosure of the Invention)

The present invention relates to a deoxidizing resin containing a deoxidizing agent, a deoxidizing packaging material formed by laminating the deoxidizing resin with another material, and a deoxidizing container prepared by processing the packaging material. The purpose of the present invention is to provide a dry preservation method which is effective in preventing defoaming capacity (oxygen absorption capacity) from lowering and preventing foaming during the preparation of packaging materials, heat processing molding of containers, or heat sealing. And

The present inventors have conducted intensive studies to achieve this object, and as a result, have removed by heating the water of crystallization and other water contained in the metal halide salt used as the oxidation promoter in the oxygen scavenger. The present inventors have found that storage in a dry state can prevent the oxygen-absorbing resin and the oxygen-absorbing wrapping material from deteriorating in oxygen-absorbing ability and prevent foaming during thermal processing and the like, and thus completed the present invention.

That is, the present invention provides a deoxidizing resin containing a deoxidizing agent composed of at least iron powder and a metal halide, and a deoxidizing packaging material formed by laminating the deoxidizing resin with another material. (This packaging material also includes a laminate of an intermediate product that should be completed by laminating with other (laminated) materials.) Or a deoxidizing container made by processing this deoxidizing packaging material The water of crystallization of the metal halide salt is removed and is substantially anhydrous. After heat treatment at a temperature of at least 20 ° C higher than the desorption temperature of water of crystallization that transfers to a salt, the resin, the packaging material or the container has substantially the same or greater hygroscopicity as the anhydrous salt of the metal halide salt. The present invention relates to a method for drying and preserving an oxygen-absorbing resin or an oxygen-absorbing packaging material, characterized in that the oxygen-absorbing resin or the oxygen-absorbing packaging material is sealed and stored in a water vapor barrier packaging container together with a desiccant.

Hereinafter, the present invention will be described in detail. The oxygen scavenger used in the present invention is composed of at least iron powder (main agent) and a metal halide salt.

As the iron powder, a fine particle having an average particle diameter of 7 to 20 / i and an apparent density of 2.3 g / cm ³ or more is preferably used, although the particle diameter is not particularly limited. Examples of such iron powder include iron powder such as reduced iron powder and sprayed iron powder, as well as iron powder obtained by crushing iron, steel chips, ground iron chips and the like.

Examples of the metal halide include alkaline earth metal halides and alkali metal halides. Among them, alkali metal halides such as calcium chloride and magnesium chloride are exemplified. These may be used alone, but may be used as a mixture with each other or with a halogenated alkali metal salt such as sodium chloride.

The oxygen scavenger is prepared by milling the fine metal powder (main agent) and the metal halide (oxidation accelerator) under an inert atmosphere such as nitrogen using a dry milling method. It is preferable to coat the iron powder while the powder is being coated, or in some cases, to coat the surface of the iron powder with a metal halide salt while grinding both. The mixing ratio of these two is appropriately adjusted depending on the intended use such as the required oxygen absorption rate, but the oxidation promoter can be, for example, 1 to 40 parts by weight per 1 part by weight of the main agent. The water content of the oxygen absorbent prepared in this manner is preferably not more than 8,000 ppm from the viewpoint of ensuring dehydration in the next dehydration step, and more preferably not more than 3,000 ppm. Particularly preferred is 0 ppm or less.

There is no particular limitation on the preparation of the oxygen-absorbing resin containing the oxygen-absorbing agent that can be prepared in this manner.For example, a polyolefin resin heated and melted using a vented twin-screw extruder or the like is used. After dispersing the oxygen scavenger, it is pelletized to obtain a resin having deoxidizing ability, that is, an oxygen scavenging resin. The mixing ratio of the oxygen scavenger and the polyolefin resin may be any of the compound composition, the masterbatch composition, etc., but the oxygen scavenger is, for example, 0.01 to 0.5 parts by weight per 1 part by weight of the resin. Can be.

Here, the present invention will be described by taking, as an example, the case where calcium chloride is used as the metal halide salt (oxidation accelerator) of the oxygen scavenger.

The calcium chloride in addition to 1, 2, 4 or also comprise water of crystallization of 6 molecules _{(C a C l 2 'n} H 2 0, n = l, 2, 4, 6) of the anhydride has, All are colorless, hygroscopic and deliquescent crystals. As is well known, calcium chloride concentrates as an aqueous solution, it becomes hexahydrate at about 30 ° C or lower, tetrahydrate at about 30-40 ° C, and dihydrate at about 30-40 ° C. Precipitates. Of these, dihydrate is further said to be monohydrate at 175 ° C and anhydrous at about 3 ° C, and is said to be Dictionary)), or it is said that it becomes anhydrous at 200 ° C (Iwanami Shoten Publishing Co., Ltd., published in 1998). In the same way as in the latter dictionary, heating at about 200 ° C or more turns it into an anhydride.

The smaller the water of crystallization, the stronger the hygroscopic power of calcium chloride, and the less water (crystal water) of dihydrate (dihydrate), not to mention anhydrous and monohydrate (water). In both cases, at around normal temperature, it cannot be removed by coexisting and enclosing with a substance generally called a desiccant or desiccant. In other words, even dihydrates are highly hygroscopic and are used as desiccants.

When heated, calcium chloride hydrate loses water of crystallization in stages, According to the confirmation of the inventor, heating at 200 ° C. or more turns into an anhydride, and all water of crystallization becomes free water. Therefore, when the oxygen scavenger and the polyolefin resin are heated and kneaded using the above-described vented twin-screw extruder, heating and kneading at a temperature of about 200 ° C or more, and calcium kneading in the oxygen scavenger when kneaded. The water of crystallization substantially becomes free water, and most of the water is removed from the vent of the twin-screw extruder, but the remainder is dispersed in the resin in the form of free water. On the other hand, when heated and kneaded at less than 200 ° C., water of crystallization remains in calcium chloride. Therefore, the dry storage method of the present invention can be advantageously applied to a deoxidized resin prepared by heating and kneading at 200 ° C. or more.

In the case of calcium chloride dihydrate, the temperature higher than the crystallization water desorption temperature at which the water of crystallization deviates and shifts to an anhydrous salt by more than 20 ° C is 220 ° C. In the case of heating at the crystallization water desorption temperature, this is an equilibrium temperature, so it takes time to desorb crystallization water and complete desorption is difficult. It is heating. The upper limit of the heating temperature is a temperature at which the quality of the matrix resin does not deteriorate due to heating.

It goes without saying that the oxygen absorbing agent of the oxygen scavenger according to the present invention has a sufficient hygroscopic power as long as it has the hygroscopic power of calcium chloride anhydride.

Immediately after preparing the oxygen-absorbing resin prepared as described above, and after storing it for several days in a moisture-proof package with an aluminum foil laminate, the water content of each was measured by the following method. . The results of both are shown schematically in Figure 1 below. In the case immediately after the preparation, only one large peak (only P was observed (solid line in FIG. 1). In the case after storage, two small peaks (P _2a and P _2b ) were observed (FIG. 2). It was found that the beak (P _{2 b} ) that appeared later was due to hydrated crystals of calcium chloride.A resin containing an oxygen scavenger in which the hydrated crystals of calcium chloride were in various states was prepared. Processes and manufactures oxygen-containing packaging materials using Upon examination, it was found that foaming tends to occur during heating, processing, etc., as the beak appearing after the above in the measurement of the water content increases. Based on the above, the difference in the area (shaded area) between the only peak immediately after preparation and the first peak (Ρ ^) after storage shown in Fig. 1 is the deoxidation immediately after preparation (heating). This suggests that the water content of the free water that was present in the base resin was monohydrate or dihydrate when it was incorporated into the anhydrous salt as water of crystallization during storage for several days. . When magnesium chloride was used, a similar test was performed, and similar results were obtained as with calcium chloride.

In the dry storage method of the present invention, a desiccant having substantially the same or higher hygroscopicity as a metal halide anhydride to be sealed in a water vapor barrier-compatible packaging container together with an oxygen-absorbing resin to be dried and stored. (Hereinafter, it may be simply referred to as "the desiccant".) Can be used by selecting from those generally known as desiccants, and anhydrous calcium chloride and magnesium chloride used as the oxygen scavenger. Any desiccant having substantially the same or higher hygroscopicity may be used. These desiccants are not always used for the first time in an anhydrous state. If they have a sufficient amount of excess adsorption (hygroscopicity) that can withstand use even in a slightly moisture-absorbed state, this type of desiccant is used. There is no problem in using it as a desiccant. In addition, a substantially equivalent or higher hygroscopicity means that it is substantially equivalent to an anhydrous calcium chloride or magnesium chloride indicated within the range of storage conditions (temperature and humidity) of the deoxidizing resin by an isothermal adsorption (hygroscopic) line. Say the same or better hygroscopicity. Examples of such a desiccant include calcium chloride, magnesium chloride, silica gel, zeolite, synthetic zeolite, activated clay, and the like, which have the above-mentioned hygroscopicity.

The above-described free water and adsorbed water are removed by enclosing the oxygen-absorbing resin and the present desiccant in a steam-barrier package and hermetically sealing the package. By applying the dry preservation method of the present invention in this manner, the free water existing in the deoxidizing resin and the free water The adsorbed water on the surface of the resin pellets is removed, preventing a decrease in the deoxidizing capacity during storage.In addition, the deoxidizing resin is heated and melted, and this is laminated with other materials to deoxygenate packaging. This makes it possible to prevent foaming during processing into materials, which in turn facilitates the production of such deoxidized packaging materials. In the case of oxygen-absorbing resins which have a high initial moisture content and are difficult to process into packaging materials, the drying and preservation method of the present invention prevents the decrease in oxygen-absorbing ability during storage. In addition, processing into packaging materials is possible without foaming.

In addition, the oxygen-absorbing resin containing the above-described oxygen scavenger is heated and melted at a temperature not lower than the temperature at which the water of crystallization of the metal halide salt contained therein becomes free water, and laminated with another material. When the dry storage method of the present invention is applied to the oxygen-absorbing packaging material obtained as described above, the free water derived from the water of crystallization of the metal halide salt and the water adsorbed on the surface of the oxygen-absorbing packaging material are It is removed by the present desiccant. This makes it possible to prevent a decrease in the oxygen-absorbing capacity during storage of the oxygen-absorbing packaging material, and to prevent foaming of the thermoformed portion when the oxygen-absorbing packaging material is heat-sealed and molded into the oxygen-absorbing container. This facilitates the formation and production of deoxidizing containers.

Furthermore, the oxygen-absorbing container obtained by molding such an oxygen-absorbing packaging material, when the drying and preservation method of the present invention is applied thereto, adsorbed water adhering to the oxygen-absorbing container becomes the present desiccant. To be removed. As a result, the oxygen scavenging container can prevent the oxygen scavenging ability from decreasing during storage. Furthermore, since there is no moisture absorption of the metal halide in the oxygen-absorbing container material, foaming is prevented when the content is filled and then sealed by heat sealing, so that the oxygen-absorbing container package has an impact during distribution. Heat seal strength enough to withstand heat is obtained.

The oxygen-absorbing packaging material of the present invention is a film-like or sheet-like packaging material.A film-like thickness is approximately 250 in or less, while a sheet-like thickness is a greater thickness. Point to. In addition, a deoxidizing container means that there is a risk of quality deterioration due to oxidation. There is no particular limitation on the shape as long as the shape is suitable for filling the container, and the shape may be a cup shape, a tray shape, a bag shape, or the like as appropriate depending on the application.

In the dry preservation method of the present invention, a deoxidizing resin or a deoxidizing packaging material and a desiccant having a moisture absorption substantially equal to or greater than that of a metal halide anhydride of an oxidation promoter are enclosed, and steam barrier packaging is performed. Package in a container. As the water vapor barrier packaging container, a metal can, a container of a metal foil laminate such as aluminum foil, a container of an aluminum vapor deposition film laminate, a container of a ceramic vapor deposition film laminate such as sily or alumina are preferably used. Can be

When the oxygen-absorbing resin or oxygen-absorbing packaging material of the present invention is dried and stored, for example, when a so-called self-reactive oxygen-desorbing sachet is used instead of the desiccant, the oxygen-absorbing resin or oxygen-absorbing packaging material is removed. Although oxygen capacity can be maintained, moisture is transferred from the oxygen scavenger sachet to them, and foaming occurs during thermal processing. Further, as another method, the oxygen in the packaging container for packaging the oxygen-absorbing resin or the oxygen-absorbing packaging material is replaced with an inert gas such as nitrogen to prevent a decrease in the oxygen-absorbing ability during storage. Although it is conceivable, this is not only costly, but also poses a danger of suffocation and other problems in work safety. From this point of view, the dry storage method of the oxygen-absorbing resin or the oxygen-absorbing packaging material of the present invention is low in cost and high in safety as compared with other storage methods, and is easily stored. It is possible to prevent a decrease in the deoxidizing ability and a trouble during the thermoforming or heat sealing. Furthermore, when the desiccant used in the dry preservation method of the present invention is stored in a moisture-permeable or moisture-permeable and heat-resistant bag-like container and used, the oxygen-absorbing resin, the oxygen-absorbing packaging material, and the oxygen-absorbing container Is preferred in terms of workability when dried and stored. Such a moisture-permeable bag-like container is preferably made of a polyethylene film, a polypropylene film, a polyester film, pulp, paper, or a nonwoven fabric of polyethylene or polypropylene. Can be used as a body. Furthermore, silica gel, zeolite, When synthetic zeolite, activated clay, etc. is used as a desiccant, the container for storing it is made of polypropylene film, polyester film, pulp, paper, or non-woven fabric of polypropylene that has both moisture permeability and heat resistance. Is preferred. The desiccant stored in these moisture-permeable and heat-resistant bag-like containers can be reused by heating, vacuum heating, drying under reduced pressure, etc., after subjecting the oxygen-absorbing resin or oxygen-absorbing packaging material to dry storage. Because it becomes. By the way, the present inventor has a feature that an oxygen-absorbing laminated package characterized in that it can have an outer layer from the outside, and is composed of an oxygen barrier layer / a nip layer / an oxygen absorbing layer / a sealant layer. And an oxygen-absorbing laminated packaging material, particularly such a packaging material, having an intermediate layer between the nylon layer and the oxygen-absorbing layer, and a multilayer including an oxygen barrier layer on the entire surface. Made an invention on an oxygen-absorbing packaging container characterized in that at least a part of the material is composed of these oxygen-absorbing laminated packaging materials, and filed a patent application for this invention (Japanese Patent Application No. Hei 10-10-18). 1 170). A part of this description is cited below.

As described above, the oxygen-absorbing laminated packaging material of this prior invention can have an outer layer from the outside, and is composed of an oxygen barrier layer / nylon layer / oxygen absorbing layer / sealant layer. Is an oxygen-absorbing laminated packaging material.

In such a laminated packaging material, the outer layer which can be provided on the outside is not particularly limited, and examples thereof include a material such as polyethylene terephthalate [PET].

As will be described later, the thickness of the nylon layer can be set to 3 to 40 m, assuming that the thickness of the entire packaging material of the prior invention is about 200 μm or less.

The oxygen barrier layer is not particularly limited, but is preferably a layer containing at least a metal foil such as aluminum or a metal deposition film. As the oxygen absorber, any of the conventionally known oxygen absorbers can be used.In particular, iron powder is the main agent, and alkali metal halides such as sodium chloride and calcium chloride or alkali metal halides are used. Those which are used as oxidation promoters are preferred from the viewpoint of hygiene and oxygen absorption capacity. The oxygen absorbing layer can be formed by kneading an oxygen absorbing agent with polyolefin or the like.

The material of the sealant layer (heat seal layer) can also be polyolefin, and the heat seal layer is preferably colored white.

When polyolefin is used as the material in each of the above-mentioned layers, such a polyolefin is preferably a polypropylene or a polybutylene copolymer having a propylene content of 70% or more.

Conventionally, a three-layered voucher has a four-layered structure when the drop impact strength is insufficient.In other words, it is common to provide another layer of film on the inside or outside of aluminum foil as a shock absorbing layer. In general, nylon and polyester are used (edited by the Japan Food Industry Association, “New Edition of the Food Industry General Encyclopedia” (1993, published by Korin Co., Ltd.)). In addition to that, the operation and effect are also different from those of the prior invention.

In more detail, nylon is usually applied to the outside of the barrier layer such as aluminum foil, etc., and there is no previous example of the structure applied to the inside in relation to the deoxidized packaging material. (A) The iron-based oxygen scavenger component increases its particle size due to the generation of mackerel as it absorbs oxygen. In other words, iron powder (鑌) protrudes from the deoxidizing agent layer. Nylon has a moderate flexibility (the expression “having a waist” is used), and particularly has excellent piercing strength. This prevents overhang. In addition, (b) the salt of the oxidation promoter of the iron-based oxygen scavenger gradually migrates through the material during heat treatment or changes over time, and corrodes the metal foil. Nylon has the effect of preventing the migration of salt. Large, thus preventing corrosion. For this reason, applying Nylon internally has the effect of preventing the laminating packaging material from peeling over time. This effect is large, and this effect is particularly remarkable in retort packaging materials, but it can also be applied to ordinary dry matter (such as seasoning granules). It is one of the greatest features of the present invention by the present inventor that the nylon has such an effect in the oxygen-absorbing laminated packaging material.

One example of the laminated packaging material of the prior invention is that a plywood layer is provided between a gas barrier layer and an oxygen-absorbing layer. The layer configuration is, for example, PET / AL (aluminum) foil / NY (nylon) It is a laminated material of / oxygen absorption layer / searant layer. This can prevent corrosion of aluminum foil (AL foil) due to migration of additives (calcium chloride, sodium chloride, etc.) in the oxygen absorbing layer (using the barrier property of nylon to salt). Also, when the iron powder oxidizes and expands, it can be prevented from contacting the aluminum foil and corroding the aluminum foil or breaking through the aluminum foil (using the high piercing strength of nylon).

Such laminates may have an intermediate layer such as polyolefin between the N Y (nylon) layer and the oxygen absorbing layer. The layer structure in this case is, for example, PET / AL foil / N Y / intermediate layer / oxygen absorbing layer / sealant layer. When the material of the intermediate layer is a polyolefin, it is preferable that the polyolefin is also a polypropylene or a polypropylene copolymer having a propylene content of 70% or more, which is the same as described above.

In such a laminated material, the ratio of the thickness of the sealant layer to the thickness of the polyolefin intermediate layer disposed between the nip layer and the oxygen absorbing layer is set to be 1: 0.3 to 1: 2.5. Are preferred. As a result, the internal pressure of the oxygen-absorbing layer increases when it is oxidized, and the oxygen-absorbing layer attempts to escape to the inside or outside. In this case, if the sealant layer is too thin, the oxidation reaction of the oxygen-absorbing layer causes the sealant layer to oxidize. A pinhole is generated at the beginning, and the components of the oxygen absorbing layer are transferred to the contents. Also, if the sealant layer is too thick, delamination will occur between the nylon layer and the polyolefin intermediate layer opposite to the sealant layer. Problems can be effectively solved.

As described above, the oxygen-absorbing packaging material of the prior invention by the present inventor is not only used for making retort bouches used for making high-quality retort foods, but also as a packaging material. Of course, it can be used for other non-retort bouch applications requiring similar performance.

Therefore, next, a packaging container made of the oxygen-absorbing laminated packaging material described above will be described.

This packaging container is an oxygen-absorbing packaging container characterized in that the entire surface is a multilayer material including an oxygen barrier layer, and at least a part thereof is made of the oxygen-absorbing laminated packaging material described above. The shape is that of a bag. This bag is preferable as a retort pouch (flat bouch, pillow-shaped voucher, standing bouch, etc.), but it is not necessarily limited to a retort pouch, and may be exposed to oxygen or light that does not undergo high-temperature, high-pressure retort treatment. Needless to say, it can be used as a packaging container for foods and other foods that deteriorate in quality. Examples of foods to be contained in the packaging container of the prior invention include foods such as semisolid porridge, solid cooked rice, powdery or granular seasonings, and the like.

The oxygen-absorbing laminated packaging material of the prior invention by the present inventor is rarely used for thick packaging materials such as sheets, and is useful for retort bouches for retort foods. , That is, about 200 μm or less.

The method for producing a packaging container such as a lettuce voucher using the oxygen-absorbing laminated packaging material of the prior invention is not particularly limited per se, and can be appropriately followed by a conventional method.

(The above is the detailed description of the invention, paragraphs 0-13 and 16-32 of the specification of Japanese Patent Application No. 10-181710). The oxygen-absorbing packaging material and oxygen-absorbing container to which the dry preservation method of the present invention is applied can be prepared according to the oxygen-absorbing laminated packaging material and the oxygen-absorbing packaging container of the prior invention. As such a deoxidizing packaging material, an oxygen-absorbing laminated packaging material having an oxygen-absorbing layer having a thickness of, for example, 10 to 25 m can be mentioned, and this is particularly preferably used for a retort container. it can.

(Brief description of drawings)

FIG. 1 shows the results of the water content of the oxygen-absorbing resin measured by the Karl Fischer water analysis method immediately after its preparation and after storage in moisture-proof packaging for several days. The solid line is the analysis of the sample immediately after preparation, and the dashed line is the analysis of the sample after several days of storage.

(Best mode for carrying out the invention)

Hereinafter, the content of the present invention will be described by way of examples, but the content of the present invention is not limited to the examples.

In the examples, the measurement of the water content, the measurement of the oxygen absorption performance, and the evaluation of the film-forming property were performed as follows.

(Measurement of water content)

The test sample (deoxygenating resin pellet) was heated to 280 ° C with a “moisture vaporizer ADP-351” manufactured by Kyoto Electronics Manufacturing Co., Ltd., and the released moisture was purged with a nitrogen stream. The moisture was measured using the company's “Karl Fisher Moisture Analyzer MKC-210”.

(Measurement of oxygen absorption performance)

The oxygen-absorbing resin pellet was heated at 180 ° C. under a pressure of 100 kg / cm ² for 5 minutes to form a sheet of 10 cm × 10 cm × 0.5 mm. This sheet Place it in a laminated bag (package container with water vapor barrier) composed of polyethylene terephthalate / A1 foil / polypropylene together with 1 ml of water, adjust the head space air volume to 50 ml, and seal with heat seal. After heating at 66 ° C for 90 minutes, the mixture was allowed to cool for 30 minutes. The oxygen concentration in the head space after heating and cooling was measured by gas chromatography, and the oxygen absorption (oxygen absorption performance) was calculated.

(Evaluation of film forming properties)

The state of the film formed by extruding the oxygen-absorbing resin pellet with a thickness of 30 m from a T-die heated to 300 ° C. was observed, and the film forming property was evaluated. Example 1

Add 100 kg of granular anhydrous calcium chloride to 200 kg of iron powder having an average particle diameter of 10 m, and pulverize anhydrous calcium chloride and coat the iron powder using a vibration mill in which the inside is replaced with an inert gas. Then, 210 kg of an oxygen scavenger was obtained. Next, 210 kg of the obtained oxygen absorber and 790 kg of polypropylene resin were kneaded at 220 ° C at a speed of 100 kg / h using a twin-screw extrusion kneader equipped with a vent. Thus, 1.0000 kg of a pellet-shaped oxygen-absorbing resin containing 21% by weight of an oxygen scavenger was obtained. The water content of the obtained deoxygenating resin was measured and found to be 680 ppm. Example 2

25 kg of the oxygen-absorbing resin pellet prepared in Example 1 and 50 kg of anhydrous calcium chloride in a desiccant packaged with a moisture-permeable packaging material (polypropylene nonwoven fabric) were mixed with 3 bags of polyethylene / aluminum foil / polyethylene. The bag was placed in a craft paper bag (package container with a water vapor barrier property) and sealed by heat sealing. After storage at room temperature for one month, the physical properties of the deoxygenated resin (water content, oxygen absorption and film forming properties) were evaluated. The results are shown in Table 1 below. Example 3

25 kg of the oxygen-absorbing resin pellet prepared in Example 1 and 50 g of synthetic zeolite (trade name “Zeoram”, manufactured by Tosoh Corporation) are wrapped in a heat- and moisture-permeable packaging material (polypropylene non-woven cloth). The three bags of the desiccant thus obtained were placed in a kraft paper bag containing polyethylene / aluminum foil / polyethylene as an inner bag, and sealed with a heat seal. After storage at room temperature for one month, the physical properties of the deoxidizing resin were evaluated in the same manner as in Example 2. The results are shown in Table 1. Example 4

When the weight of the desiccant used for storing the oxygen-absorbing resin in Example 3 was measured, a weight increase of 11 g was recognized. The desiccant contained in the heat-resistant and moisture-permeable packaging material is regenerated by heating at 130 ° C for 2 days under vacuum, and stored in the same manner as in Example 2 using the new deoxidizing resin prepared in Example 1. Later, its physical properties were evaluated. The results are shown in Table 1. Example 5

25 kg of the oxygen-absorbing resin pellet prepared in Example 1 and 50 bags of anhydrous calcium chloride were packaged in a moisture-permeable packing material (polypropylene nonwoven fabric) and 3 bags of a desiccant were deposited on silica-deposited polyethylene terephthalate Z polyethylene. And sealed with a heat seal. After storage at room temperature for one month, the physical properties of the deoxidizing resin were evaluated in the same manner as in Example 2. The results are shown in Table 1. Example 6

A desiccant obtained by packaging 25 kg of the pellet of the oxygen-absorbing resin prepared in Example 1 and 50 g of synthetic zeolite having an initial moisture absorption of 10 wt% of its own weight in a heat-resistant and moisture-permeable packaging material (polypropylene nonwoven fabric). 3 bags and polyethylene / aluminum foil / polyethylene inner bag It was placed in a rough paper bag and sealed by heat sealing. After storage at room temperature for one month, the physical properties of the deoxidizing resin were evaluated in the same manner as in Example 2. The results are shown in Table 1. Example 7

Add 10 kg of anhydrous magnesium chloride to 200 kg of iron powder with an average particle size of 100 μm, and pulverize anhydrous magnesium chloride using a vibrating mill in which the inside is replaced with an inert gas, and pulverize the iron powder. Coating was performed to obtain 21 O kg of an oxygen scavenger. Next, 10 kg of the obtained oxygen absorber and 123 kg of the polypropylene resin were kneaded with a vented twin-screw extruder at 250 ° C with a speed of 150 kg / h. As a result, 33 kg of a pellet-shaped oxygen-absorbing resin containing 63% by weight of an oxygen-absorbing agent was obtained (the oxygen-absorbing agent content was 3 times that of Example 1). The water content of the obtained oxygen-absorbing resin pellet was measured and found to be 2,000 ppm. Example 8

Polyethylene / aluminum foil / polyethylene were mixed with 25 kg of the oxygen-absorbing resin pellet prepared in Example 7 and 3 bags of desiccant obtained by packing 50 g of anhydrous calcium chloride with a moisture-permeable packaging material (nonwoven polypropylene fabric). It was placed in an inner kraft paper bag and sealed by heat sealing. After storage at room temperature for one month, the dried oxygen-absorbing resin pellets were mixed well with 50 _kg of polypropylene resin pellets, and the physical properties were evaluated in the same manner as in Example 2. The results are shown in Table 1. Comparative Example 1

25 kg of the oxygen-absorbing resin pellet prepared in Example 1 was placed in a kraft paper bag having a polyethylene / aluminum foil / polyethylene inner bag without enclosing a desiccant and sealed with a heat seal. After storage at room temperature for one month, the deoxygenated tree was treated as in Example 2. The physical properties of the fat were evaluated. The results are shown in Table 1. Comparative Example 2

25 kg of the oxygen-absorbing resin pellet prepared in Example 1 and 3 bags of a self-reactive oxygen absorbent small bag (trade name “Ageless Z-500”, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and polyethylene / A 1 foil / polyethylene inside It was placed in a kraft paper bag and sealed by heat sealing. After storage at room temperature for one month, the physical properties of the deoxidizing resin were evaluated in the same manner as in Example 2. The results are shown in Table 1. Comparative Example 3

Addition of 10 kg of granular anhydrous calcium chloride to 200 kg of iron powder having an average particle size of 10 zm, and grinding and coating of anhydrous calcium chloride using a vibration mill in which the inside is replaced with an inert gas, 210 kg of oxygen scavenger were obtained. Next, 2 10 kg of the obtained oxygen scavenger and 790 kg of the polypropylene resin were kneaded at 160 ° C at a speed of 10 Okg / h using a biaxial extrusion kneader equipped with a vent to remove the oxygen scavenger. We obtained 1,000 kg of a pellet-shaped deoxygenating resin containing 21 wt%. The water content of the obtained deoxygenating resin pellet was measured and found to be 1,10 ppm. Comparative Example 4

Craft containing 25 kg of the oxygen-absorbing resin pellet prepared in Comparative Example 3 and 50 g of anhydrous calcium chloride in a desiccant packaged with a moisture-permeable packaging material (polypropylene nonwoven fabric) and polyethylene / aluminum foil / polyethylene inner bag. It was put in a paper bag and sealed by heat sealing. After storage at room temperature for one month, the physical properties of the deoxidizing resin were evaluated in the same manner as in Example 2. The results are shown in Table 1. Table 1

In the Karl Fischer moisture analysis of Examples 2 to 6 and 8, no clear second peak was observed as compared with Comparative Examples 1, 2 and 4. Example 9

Using an extruder, the oxygen-absorbing resin pellets dried and stored in Example 2 were placed between unstretched polypropylene [CPP] (30 jm) and titanium oxide-containing white unstretched polypropylene [CPPw] (30 rn). The deoxidized layer (2) was formed by extruding at 300 ° C from a T-die and sandwich laminating. Subsequently, the CPP surface of the laminate was laminated with a urethane-based adhesive by a usual dry lamination method. Detoxified polyethylene terephthalate [PET] / aluminum foil Deoxygenated laminate by laminating with a urethane-based adhesive using a normal dry laminating method with a stretched nylon (15 mm) nylon surface The obtained oxygen-absorbing packaging material was wound into a roll with a width of 900 mm and a length of 1,000 m 每 on a vinyl chloride pipe. The layer configuration of Become like

That is, PE TZ aluminum foil Z stretch nylon (15 zm) / CPP (30 jum) / Deoxygenation layer (ST ^ n / CP Pw iS O ^ nc Example 10

Drying agent prepared by packing 50 g of anhydrous calcium chloride with a moisture-permeable packing material (polyethylene non-woven fabric) on both sides of the roll-shaped deoxidizing packing material prepared in Example 9 was placed in each of two bags, and PET / aluminum foil was used. It was packaged with a gum tape using a packaging material made of polypropylene (water vapor barrier property) and stored at room temperature for one month. Was opened one month later, create an inner area that is 3 3 0 cm ² three-way Shirupauchi, after containing water 1 m 1 in Pauchi, the air amount of dead space to further heat sealed opening 5 0 A four-sided heat seal patch adjusted to ml was prepared. 1 2 1 After 8 hours of retort treatment with (:), the oxygen concentration in the head space was measured by gas chromatography to be 4.0%, and the oxygen absorption amount was 8.8 ml. The four-sided heat seal porch with 200 m1 of water poured into the one-side seal pallet and heat-sealed the opening is subjected to a retort treatment at 121 ° C for 8 minutes, and a pressure test of 100 bags of pallets ( Conditions: 100 kgf / bag, 1 minute), but no problem was found.

After storing the roll of the oxygen-absorbing packaging material prepared in Example 9 at room temperature for one month in the same manner as in Example 10 except that no desiccant was used, It was prepared and subjected to oxygen concentration measurement and pressure resistance test in the head space. As a result, the oxygen concentration in the headspace was 6.3%, and the oxygen absorption was 7.8 ml, indicating a decrease in oxygen absorption capacity. In the pressure test, 25 out of 100 bags were broken. Observation of the state of bag breakage revealed that slight foaming was observed in the oxygen-absorbing resin layer in all the heat-sealed portions of the four-side heat sealed pouch. Example 1 1

A standing patch was prepared from the deoxidized packaging material prepared in Example 9 (internal area: 330 cm ² ). Put 2,400 bags of standing pouch and 1 bag of 50 g of anhydrous calcium chloride in a desiccant packed with moisture-permeable packing material (polyethylene non-woven fabric) in a bag made of PET / aluminum foil / polyethylene. And stored at room temperature for 1 month. One month later, the package was opened, 1 ml of water was put in the standing patch, and the opening was heat-sealed to prepare a patch in which the air volume in the head space was adjusted to 50 ml. After the patch was retorted at 121 ° C. for 8 minutes, the oxygen concentration in the head space was measured by gas chromatography to be 4.7%, and the oxygen absorption amount was 8.5 ml. In addition, after filling the opening with 200 m1 of water in the standing pouch and heat-sealing the opening, retort treatment was performed at 121 ° C for 8 minutes. : L O Okgf / bag, 1 minute), but all was well. Comparative Example 6

After storing the standing vouches prepared in the same manner as in Example 11 except that no desiccant was used, the oxygen concentration in the head space was measured in the same manner as in Example 11 after storage as in Example 11 And a pressure test. As a result, the oxygen concentration in the head space was 6.5%, and the oxygen absorption amount was 7.7 ml, indicating a decrease in the oxygen absorption capacity. In the pressure test, 20 bags of 100 bags were broken. When observing the state of bag breakage, slight foaming was observed only in the deoxidized resin layer in the portion that was filled with water in the standing patch and finally heat-sealed. Example 12

Add 40 kg of granular anhydrous calcium chloride to 200 kg of iron powder having an average particle size of 1 and pulverize the anhydrous calcium chloride using a vibrating mill in which the inside is replaced with an inert gas and iron powder. Was applied to obtain 240 kg of an oxygen scavenger. Next, the obtained oxygen scavenger and low-density polyethylene resin (960 kg) were kneaded using a vented twin-screw extruder at 24 CTC at a speed of 100 kg / h, and the resulting mixture was demixed. 1,200 kg of a pellet-shaped oxygen-absorbing resin containing 20 wt% of an oxygenating agent was obtained. The water content of the deoxygenating resin was measured and found to be 320 ppm. Example 13

25 kg of the oxygen-absorbing resin pellet prepared in Example 12 and 50 g of anhydrous calcium chloride in a desiccant packaged with a moisture-permeable packaging material (polypropylene nonwoven fabric) were mixed with 3 bags of polyethylene / aluminum foil / polyethylene. It was placed in a craft paper bag (steam barrier container) and sealed by heat sealing. After storage at room temperature for one month, the water content of the deoxygenating resin was measured and found to be 250 ppm. Example 14

The dried oxygen-absorbing resin pellets of Example 13 were extruded at 300 ° C. from a T-die using an extruder on titanium oxide-containing white low-density polyethylene [LD P Ew] (30 m). A deoxygenation layer (20 μm) was formed to obtain a laminate. The layer structure of this laminate is as follows.

That is, the deoxidizing layer (20 m) / LDP Ew (30 m).

After the surface of the oxygen-desorbing layer of the obtained laminate is corona-treated, the PET / aluminum foil stretched nylon (15 zm) laminated with a urethane-based adhesive by a normal dry lamination method and a urethane-based adhesive By dry laminating with the agent, an oxygen-absorbing packaging material as an oxygen-absorbing laminate was obtained. The resulting deoxidized packaging material was wound into a vinyl chloride pipe with a width of 900 mm and a length of 1000 m in a roll. The layer configuration of this laminate is as follows. PET / aluminum foil / stretched nylon (15 m) / deoxidation layer (20 m) / LDPE w (30 m). Example 15

A roll of oxygen-absorbing wrapping material prepared in Example 14 was placed on both sides with a desiccant packed with 50 g of anhydrous calcium chloride in a moisture-permeable packing material (polyethylene non-woven fabric). PET / aluminum foil / polypropylene It was packaged with a wrapping material (steam barrier property) using gum tape and stored at room temperature for one month. One month later, open it, create a 20 cm x 20 cm flat patch, and, together with 30 ml of air, enclose a highly air-permeable nonwoven pouch containing a saturated sodium bromide aqueous solution and sodium bromide powder for humidity control purposes. After storing for 1 month in a 24 ° C. environment with the internal humidity kept at 58% RH, the oxygen concentration of the gas in the patch was measured. In addition, under the same conditions, the patch after storage for 6 months was visually observed to confirm corrosion of the aluminum foil. The results are shown in Table 2 below. Table 2

As shown in the above table, the deoxidation performance (oxygen absorption performance) is good, and at the same time, the nylon layer is disposed between the aluminum foil, which is a gas barrier layer, and the deoxidizing layer, so that the corrosion of the aluminum foil is reduced. Was prevented. Comparative Example 7 The surface of the oxygen-absorbing layer (= oxygen absorbing layer) of the oxygen-absorbing layer (20 m) / LDP Ew (30 jm), which is the two-layer laminate obtained in Example 14, was subjected to corona treatment. A PET / aluminum foil laminated with a urethane-based adhesive by a usual dry lamination method and dry-laminated with a urethane-based adhesive were used to obtain a deoxidized packaging material as a deoxidized laminate. The obtained oxygen-absorbing packaging material was wound into a vinyl chloride pipe in a roll shape at a width of 900 mm and a length of 1,000 m. The layer structure of this laminate is as follows.

That is, PET / aluminum foil / oxygen absorbing layer (20 zm) / LD P Ew (30 m). Comparative Example 8

The same evaluation as in Example 15 was performed for the laminate obtained in Comparative Example 7. The results are also shown in Table 2 above. As shown in this table, the oxygen scavenging ability was good, but the nylon layer was not disposed between the aluminum foil, which is a layer of gas, and the oxygen scavenging layer (oxygen absorbing layer). Temporary corrosion of the aluminum foil was observed. Example 16

An oxygen-absorbing packaging material was obtained in exactly the same manner as in Example 9 except that the thickness of the oxygen-absorbing layer in Example 9 was changed from 2 to 20 m. Example 17

When the oxygen-absorbing packaging material of Example 16 was used in the same manner as in Example 11, the oxygen concentration was 5.1%, the oxygen absorption amount was 8.3 ml, and the pressure resistance test was all satisfactory. . An opening test was performed from the notch of the standing bouch. But there was no problem. Comparative Example 9

An attempt was made to obtain a deoxidized laminate in which the thickness of the deoxidized layer in Example 9 was changed from 27 m to 8 zm, but stable extrusion from the T-die was difficult, and the desired laminate was obtained. I can't do it. Comparative Example 10

An oxygen-absorbing packaging material was obtained in exactly the same manner as in Example 9 except that the thickness of the oxygen-absorbing layer in Example 9 was changed from 27 zm to 40 μm. Comparative Example 1 1

When the deoxidizing packaging material of Comparative Example 10 was carried out in the same manner as in Example 11, the oxygen concentration was 4.3%, the oxygen absorption amount was 8.7 ml, and all the pressure resistance tests were not problematic. An opening test was conducted from the notch of the standing patch, but it took a considerable amount of force to open. The results of Example 17 and Comparative Example 11 show that even if the thickness of the oxygen-absorbing layer (oxygen-absorbing layer) was doubled, the oxygen-absorbing ability was hardly improved, and the thickness of the oxygen-absorbing layer was 25 / m2. Even with the above thickness, the oxygen scavenger is not effectively used, indicating that the oxygen scavenging ability is hardly improved. On the other hand, the standing patch in Comparative Example 11 had a larger film thickness than that of Example 17, so that the opening property was deteriorated. Reference example

A standing patch (12 Omm) made of the same packaging material in Example 9 x 180 mm), put a total of 250 g of milled rice (20 g) and water (230 g) in the inside, heat seal, seal, and heat sterilize under pressure (1 2 1 ° (, 8 minutes) After cooling for 1 day, when opened, porridge was formed, which had no off-flavor and tasted the same as "porridge" made at home in a clay pot for a long time. .

(Industrial applicability)

According to the oxygen-absorbing resin according to the present invention, the oxygen-absorbing packaging material obtained by laminating the same with other materials, and the method for drying and storing an oxygen-absorbing container prepared using this packaging material, Moisture absorption by the metal halide salt used as an accelerator is prevented, which in turn prevents a decrease in the oxygen-absorbing capacity during storage, and furthermore, the oxygen-absorbing resin or the oxygen-absorbing packaging material is used as it is. In such a case, even if there is moisture absorbed so much as to hinder the heat (molding) processing, moisture is removed to such an extent that the heat (molding) processing is not hindered. Deoxygenation during heat sealing Foaming of the container can be prevented.

Claims

The scope of the claims

1. An oxygen-absorbing resin containing an oxygen-absorbing agent composed of at least iron powder and a metal halide salt, an oxygen-absorbing packaging material formed by laminating this oxygen-absorbing resin with another material, or this oxygen-absorbing material. The deoxidizing container prepared by processing the packaging material is heat-treated at a temperature higher than the desorption temperature of crystal water, at which the crystal water of the metal salt is removed and substantially shifts to an anhydrous salt, by 20 ° C or more. After that, it is preferable that the resin, the packaging material or the container is sealed and stored in a steam-barrier packaged container together with a desiccant having a hygroscopicity substantially equal to or higher than that of the anhydrous salt of the metal halide. A method for drying and storing a deoxidizing resin or a deoxidizing packaging material.

2. The method for drying and preserving an oxygen-absorbing resin or an oxygen-absorbing packaging material according to claim 1, wherein the metal halide is calcium chloride and / or magnesium chloride.

3. One or more substances selected from the group consisting of calcium chloride, magnesium chloride, silica gel, zeolite, synthetic zeolite, and activated clay, in which the desiccant having substantially the same or greater hygroscopicity as the metal halide anhydride is used. The dry preservation method of an oxygen-absorbing resin or an oxygen-absorbing packaging material according to claim 1 or 2, wherein

4. A desiccant having a hygroscopicity substantially equal to or greater than that of a metal halide anhydride is sealed in a moisture-permeable heat-resistant bag-shaped container. Drying and preservation method of the deoxidizing resin or the deoxidizing packaging material.

5. A bag in which the packaging material is composed of an outer layer / oxygen barrier layer / Z-opening layer / oxygen absorbing layer / sealant layer from the outside and a thickness of the oxygen absorbing layer of 10 to 25 m. An oxygen-absorbing container to which the drying and preservation method according to any one of claims 1 to 4 is applied, wherein the container is a deoxygenating container.

6. Note that an intermediate layer is further provided between the nylon layer and the oxygen absorbing layer. The deoxidizing container according to claim 5, wherein