JP2004195971A - Food preserving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a food preserving method using a packaging material that excels in various gas barrier properties, heat resistance, acid resistance, moisture-proof property, heat sealing property, transparency, and the like, that has a suitability for filling and packing and preserving the contents and the like, that does not cause discoloration of the laminated film after boil processing and lowering of laminate strengths after a long-term storing, and that excels in environmental compatibility, economical aspects, and the like. <P>SOLUTION: The food preserving method comprises sealing a food using a gas barrier laminate film which comprises an outer layer consisting of a thermoplastic resin, an inner layer consisting of a heat-sealable thermoplastic resin, and an adhesive layer formed with an adhesive for lamination mainly composed of an epoxy resin composition. In the epoxy resin cured product formed from the epoxy resin composition a specific skeletal structure is contained in an amount of 40 wt.% or more. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention has various gas barrier properties, heat resistance, moisture resistance, acid resistance, heat sealability, pinhole resistance, piercing resistance, excellent transparency, etc. Further, the present invention relates to a method for preserving food using a packaging material which is extremely excellent in environmental suitability and economy.

  Conventionally, packaging materials for filling and packaging foods are required to have excellent moisture barrier properties and, in particular, excellent gas barrier properties for preventing permeation of oxygen gas, water vapor, aroma components, and the like. Laminated films, etc., in which a sealant layer or the like is laminated on a coated film coated with polyvinylidene chloride (PVDC) resin, which has excellent properties, are used. These are made into bags, and filling and packaging bags of various forms are manufactured. I was However, when a PVDC-based resin is used as a gas barrier material, a high effect is exhibited with respect to various gas barrier properties such as oxygen and water vapor. Due to its inclusion, it causes toxic gases such as dioxin when incinerated and disposed of, causing problems such as lack of suitability for disposal and environmental destruction, as well as lack of environmental suitability. .

  Polyvinyl alcohol-coated films and ethylene-vinyl alcohol copolymer (EVOH) films have been used as alternative gas barrier materials, but these gas barrier materials have extremely high gas barrier properties under dry conditions. However, under high-humidity conditions, there is a problem that the gas barrier properties are significantly reduced. Further, since these gas barrier materials are more expensive than PVDC-based resins, they are disadvantageous in terms of cost in the production of packaging bags (for example, see Patent Document 1).

  When a laminated film is produced by laminating the above gas barrier material and various thermoplastic resins, a two-component polyurethane adhesive comprising a main agent having an active hydrogen group such as a hydroxyl group and a curing agent having an isocyanate group is used. Although the method of performing lamination using an agent or the like has become mainstream, these two-component polyurethane adhesives generally ensure a sufficient adhesiveness since the curing reaction is not so fast. Therefore, after the lamination, it was necessary to perform curing by aging for a long time of 1 to 5 days. In addition, since a curing agent having an isocyanate group is used, if unreacted isocyanate groups remain after curing, the remaining isocyanate groups react with moisture in the air to generate carbon dioxide, and thus are contained in the laminated film. There were problems such as generation of bubbles. As a method for solving these problems, it has been proposed to add a catalyst or a coupling agent to the polyurethane-based adhesive (see Patent Document 2). However, the addition of the catalyst shortens the pot life and increases workability. There are problems such as worsening.

  Further, when the laminated film having the EVOH layer as the intermediate layer is subjected to the boil treatment, not only the gas barrier property after the boil treatment is deteriorated, but also the whitening of the EVOH layer has been a problem. In addition, in forming such a laminated film, an adhesive in which a polyester polyol and a polyisocyanate compound are combined is generally known. However, during such operations as stacking after boiling and retorting, such adhesives may cause partial adhesion failure due to unintended bending, resulting in poor appearance, acid resistance in content resistance, Depending on the boil resistance and the contents or the base material, deterioration of the performance over time may become a problem. As a method for solving these problems, a laminate using a polyester-based adhesive has been proposed (see Patent Document 3). However, under the condition of high humidity, the gas barrier property is significantly reduced. Remains unresolved.

JP-A-10-71664 JP-A-9-316422 Japanese Patent No. 30023229

  The object of the present invention is to provide various gas barrier properties, heat resistance, acid resistance, moisture resistance, heat sealability, excellent transparency, etc., filling and packaging of contents, storage suitability, etc. An object of the present invention is to provide a method for preserving food using a packaging material which does not cause discoloration or decrease in laminate strength after long-term storage, and which is extremely excellent in environmental suitability and economy.

  The present inventors have made intensive studies to solve the above problems, and produced a packaging bag using a laminated film laminated using a high gas barrier adhesive containing a specific epoxy resin composition as a main component, By filling with food, it is excellent in various gas barrier properties, heat resistance, acid resistance, moisture resistance, heat sealability, transparency, etc., has suitability for filling and packaging of contents, storage suitability, etc., laminated film after boil treatment The present inventors have found that a method for preserving food which does not cause discoloration or decrease in laminate strength after long-term storage and which is extremely excellent in environmental suitability and economic efficiency can be obtained, thereby completing the present invention.

  That is, the present invention provides a gas barrier laminate including an outer layer made of a thermoplastic resin, an inner layer made of a thermoplastic resin having a heat sealing property, and an adhesive layer formed using an adhesive for lamination containing an epoxy resin composition as a main component. A method for preserving food, wherein the food is sealed using a film, wherein the epoxy resin cured product formed from the epoxy resin composition contains 40% by weight or more of the skeleton structure of the formula (1). It relates to the storage method.

  The storage method of the present invention is to prepare a gas-barrier laminated film using a laminating adhesive containing a high-gas-barrier epoxy resin composition as a main component as a substantial gas barrier material, and use the laminated film to produce food. It is characterized by saving. The gas barrier laminate film has various gas barrier properties such as oxygen and water vapor and aroma components in a wide range from low humidity conditions to high humidity conditions, and its lamination strength, heat sealability, heat resistance, acid resistance, moisture resistance, It is excellent in oil resistance, transparency, environmental compatibility, economy, etc., and from dry food to liquid food by using the gas barrier laminate film and the packaging bag obtained by making the laminate film. And a storage method that is excellent in storage and storage stability, suitability for filling and packaging, environmental suitability, economy, and the like can be provided.

  In the storage method of the present invention, the gas barrier laminate film used when sealing food is characterized in that it includes an outer layer made of a thermoplastic resin, and a thermoplastic resin layer having heat sealability, and illustrates a layer configuration. Then, an outer layer made of a thermoplastic resin / an adhesive layer / an inner layer made of a thermoplastic resin having heat sealing properties, an outer layer made of a thermoplastic resin / an adhesive layer / an intermediate layer made of a thermoplastic resin / adhesive layer / having heat sealing properties. Examples include, but are not limited to, an inner layer made of a thermoplastic resin.

  The gas barrier laminated film used in the storage method of the present invention, the outer layer and the intermediate layer made of a thermoplastic resin, for example, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polyolefin resin film such as polypropylene, polyethylene terephthalate , Polyester resin films such as polybutylene terephthalate, polyamide resin films such as nylon 6, nylon 6,6, and meta-xylene adipamide (N-MXD6), polyacrylonitrile films, poly (meth) acrylic films, and polystyrene -Based film, polycarbonate-based film, saponified ethylene-vinyl acetate copolymer (EVOH) -based film, polyvinyl alcohol-based film, paper such as carton, metal foil such as aluminum and copper, and these materials Films coated with various polymers such as polyvinylidene chloride (PVDC) resin, polyvinyl alcohol resin, ethylene-vinyl alcohol copolymer (EVOH), acrylic resin, and various inorganic compounds or metals such as silica, alumina, and aluminum are deposited. Film, a film in which an inorganic filler or the like is dispersed, a film having an oxygen scavenging function, or the like can be used. In addition, the inorganic filler can be dispersed in various polymers to be applied. Examples of the inorganic filler include silica, alumina, mica, talc, aluminum flake, glass flake, and the like.A layered silicate such as montmorillonite is preferable, and examples of the dispersion method include an extrusion kneading method and mixing with a resin solution. A conventionally known method such as a dispersion method can be used. Examples of the method of imparting the oxygen scavenging function include, for example, hindered phenols, vitamin C, vitamin E, organophosphorus compounds, gallic acid, low molecular weight organic compounds that react with oxygen such as pyrogallol, and cobalt, manganese, nickel, and iron. And a method in which a composition containing a transition metal compound such as copper is used at least in part.

  The thickness of these film materials is practically about 10 to 300 μm, preferably about 10 to 100 μm. In the case of a plastic film, it may be stretched in a uniaxial or biaxial direction.

  As the outer layer made of a thermoplastic resin, a biaxially-stretched polyolefin-based resin film, a biaxially-stretched polyester-based resin film, or a biaxially-stretched polyamide-based resin film having higher strength than an unstretched film is preferable.

  As the inner layer made of a thermoplastic resin having a heat sealing property, a thermoplastic resin film having a generally used heat sealing property can be used in the same manner, but in consideration of the development of a good heat sealing property, It is preferable to select a polyolefin-based resin film such as a polyethylene film, a polypropylene film, and an ethylene-vinyl acetate copolymer.

  In addition, various surface treatments such as a flame treatment and a corona discharge treatment are performed on the surfaces of the outer layer and the inner layer of the gas barrier laminated film as necessary so that an adhesive layer without defects such as film breakage and repelling is formed. Is desirable. Further, various primer layers may be formed as necessary. Such treatment promotes good adhesion of the adhesive layer to various film materials.

  Further, the surface of the outer layer and the inner layer of the gas barrier laminate film may be subjected to a printing treatment. When performing a printing process, general printing equipment used for printing on a conventional thermoplastic resin film, such as a gravure printing machine, a flexographic printing machine, and an offset printing machine, can be similarly applied. In addition, for the ink forming the printing layer, a conventional thermoplastic resin film formed from pigments such as azo-based and phthalocyanine-based, resins such as rosin, polyamide resin and polyurethane, and solvents such as methanol, ethyl acetate, and methyl ethyl ketone. Inks that have been used for the print layer on the ink may be applied as well.

  The gas barrier laminated film may include a layer made of a composition having an oxygen scavenging function. The composition having an oxygen-scavenging function includes, for example, kneading a low-molecular-weight organic compound that reacts with oxygen, such as hindered phenols, vitamin C, vitamin E, an organic phosphorus compound, gallic acid, and pyrogallol, and a metal powder such as iron into a resin. Olefin polymers and oligomers having a carbon-carbon double bond in the molecule such as polybutadiene, polyisoprene, and butadiene / isoprene copolymers, and polyamides having a meta-xylylene structure. And an oxygen-absorbing resin to which a transition metal compound such as copper is added.

  The gas barrier laminate film in the storage method of the present invention is obtained by laminating an outer layer made of a thermoplastic resin or a thermoplastic resin layer having a heat seal property. When laminating each layer constituting the laminated film, at least one layer is formed. Is bonded with a laminating adhesive mainly composed of an epoxy resin composition comprising an epoxy resin and an epoxy resin curing agent. As for an adhesive layer other than the adhesive layer using the laminating adhesive, another adhesive such as a polyurethane adhesive may be used, or the resins may be welded to each other.

  The laminating adhesive in the preservation method of the present invention has an epoxy resin composition composed of an epoxy resin and an epoxy resin curing agent as a main component. % By weight, preferably 45% by weight or more, more preferably 50% by weight or more. When the skeleton structure of the above formula (1) is contained at a high level in the epoxy resin cured product forming the adhesive layer, high gas barrier properties are exhibited. Hereinafter, the epoxy resin and the epoxy resin curing agent that form the cured epoxy resin will be described.

  In the adhesive for lamination according to the present invention, the epoxy resin may be any of an aliphatic compound, an alicyclic compound, an aromatic compound or a heterocyclic compound. An epoxy resin containing a group moiety in the molecule is preferable, and an epoxy resin containing the skeleton structure of the above formula (1) in the molecule is more preferable. Specifically, an epoxy resin having a glycidylamine moiety derived from meta-xylylenediamine, an epoxy resin having a glycidylamine moiety derived from 1,3-bis (aminomethyl) cyclohexane, and a glycidylamine derived from diaminodiphenylmethane Epoxy resin having a glycidylamine site and / or a glycidyl ether site derived from para-aminophenol, epoxy resin having a glycidyl ether site derived from bisphenol A, and a glycidyl ether site derived from bisphenol F. Resin having a glycidyl ether moiety derived from phenol novolak, epoxy resin having a glycidyl ether moiety derived from resorcinol And the like. Among them, epoxy resin having a glycidylamine moiety derived from meta-xylylenediamine, epoxy resin having a glycidylamine moiety derived from 1,3-bis (aminomethyl) cyclohexane, and bisphenol F An epoxy resin having a glycidyl ether moiety and a epoxy resin having a glycidyl ether moiety derived from resorcinol are preferred.

  Further, it is more preferable to use an epoxy resin having a glycidyl ether moiety derived from bisphenol F or an epoxy resin having a glycidylamine moiety derived from meta-xylylenediamine as a main component, and is preferably derived from meta-xylylenediamine. It is particularly preferable to use an epoxy resin having a glycidylamine moiety as a main component.

  Further, in order to improve various properties such as flexibility, impact resistance, and wet heat resistance, the above various epoxy resins can be mixed and used at an appropriate ratio.

  The epoxy resin in the present invention is obtained by the reaction of various alcohols, phenols and amines with epihalohydrin. For example, an epoxy resin having a glycidylamine moiety derived from metaxylylenediamine can be obtained by adding epichlorohydrin to metaxylylenediamine.

  Here, the glycidylamine moiety includes a mono-, di-, tri- and / or tetra-glycidylamine moiety that can replace the four hydrogen atoms of the diamine in xylylenediamine. Each ratio of mono-, di-, tri- and / or tetra-glycidylamine sites can be changed by changing the reaction ratio between metaxylylenediamine and epichlorohydrin. For example, an epoxy resin having mainly a tetraglycidylamine site can be obtained by subjecting metaxylylenediamine to an addition reaction with about 4-fold molar amount of epichlorohydrin.

  Epoxy resins are prepared by adding an excess of epihalohydrin to various alcohols, phenols and amines in the presence of an alkali such as sodium hydroxide at 20 to 140 ° C, preferably 50 to 120 ° C for alcohols and phenols and amines. In the case of the above, the reaction is carried out at a temperature of 20 to 70 ° C., and the resulting alkali halide is separated to synthesize.

  Although the number average molecular weight of the produced epoxy resin varies depending on the molar ratio of epihalohydrin to various alcohols, phenols and amines, it is about 80 to 4000, preferably about 200 to 1000, and more preferably about 200 to 500. Is more preferable.

  In the laminating adhesive in the storage method of the present invention, the epoxy resin curing agent may be any of an aliphatic compound, an alicyclic compound, an aromatic compound or a heterocyclic compound, and may be a polyamine, a phenol, or an acid. Commonly used epoxy resin curing agents such as anhydrides or carboxylic acids can be used. These epoxy resin curing agents can be selected according to the intended use of the laminated film and the required performance in the intended use.

  Specifically, polyamines include aliphatic amines such as ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; aliphatic amines having an aromatic ring such as metaxylylenediamine and paraxylylenediamine; and 1,3- Examples include alicyclic amines such as bis (aminomethyl) cyclohexane, isophoronediamine, norbornanediamine, and aromatic amines such as diaminodiphenylmethane and metaphenylenediamine.

  Reaction products of these polyamines with epoxy resins or monoglycidyl compounds, reaction products with alkylene oxides having 2 to 4 carbon atoms, addition products with epichlorohydrin, and polyamines of these Reaction product with a polyfunctional compound having at least one acyl group capable of forming an amide group site to form an oligomer by reacting with the amide group site, and forming an amide group site by forming a reaction with these polyamines to form an oligomer For example, a reaction product of a polyfunctional compound having at least one acyl group with a monovalent carboxylic acid and / or a derivative thereof can be used.

Examples of the phenols include multi-substituted monomers such as catechol, resorcinol, and hydroquinone, and resol-type phenol resins.
Examples of the acid anhydrides or carboxylic acids include aliphatic acid anhydrides such as dodecenyl succinic anhydride and polyadipic anhydride, and alicyclic acid anhydrides such as (methyl) tetrahydrophthalic anhydride and (methyl) hexahydrophthalic anhydride. And aromatic acid anhydrides such as phthalic anhydride, trimellitic anhydride and pyromellitic anhydride, and carboxylic acids thereof.

In consideration of the expression of high gas barrier properties, an epoxy resin curing agent containing an aromatic moiety in the molecule is preferable, and an epoxy resin curing agent containing the skeleton structure of the above formula (1) in the molecule is more preferable.
Specifically, meta-xylylenediamine or para-xylylenediamine, and reaction products thereof with epoxy resins or monoglycidyl compounds, reaction products with alkylene oxides having 2 to 4 carbon atoms, epichlorohydrin Reaction product with a polyfunctional compound having at least one acyl group capable of forming an amide group site to form an oligomer by reaction with these polyamines, and reaction with these polyamines It is more preferable to use a reaction product of a polyfunctional compound having at least one acyl group and a monovalent carboxylic acid and / or a derivative thereof, which can form an amide group site to form an oligomer.

In consideration of high gas barrier properties and good adhesion with various film materials, the following reaction products (A) and (B), or (A), (B), and It is particularly preferable to use the reaction product of (C).
(A) meta-xylylenediamine or para-xylylenediamine
(B) a polyfunctional compound having at least one acyl group capable of forming an amide group site by reaction with a polyamine to form an oligomer
(C) a monovalent carboxylic acid having 1 to 8 carbon atoms and / or a derivative thereof

  (B) Acrylic acid, methacrylic acid, maleic acid, fumaric acid, succinic acid, apple, and the like are polyfunctional compounds having at least one acyl group capable of forming an amide group site by reaction with a polyamine to form an oligomer. Acids, tartaric acid, adipic acid, isophthalic acid, terephthalic acid, pyromellitic acid, carboxylic acids such as trimellitic acid and derivatives thereof, for example, esters, amides, acid anhydrides, acid chlorides and the like, especially acrylic acid, Methacrylic acid and derivatives thereof are preferred.

  Further, monovalent carboxylic acids having 1 to 8 carbon atoms such as formic acid, acetic acid, propionic acid, butyric acid, lactic acid, glycolic acid, and benzoic acid and derivatives thereof, for example, esters, amides, acid anhydrides, acid chlorides and the like. The starting polyamine may be reacted with the above polyfunctional compound. The amide group site introduced by the reaction has a high cohesive force, and a high ratio of the amide group site in the epoxy resin curing agent provides higher oxygen barrier properties and good adhesion to various film materials. Strength is obtained.

  The reaction molar ratio of (A) and (B) or (A), (B), and (C) is the reactivity of (B) with respect to the number of amino groups contained in (A), respectively. As a ratio of the number of functional groups, or a ratio of the total number of reactive functional groups contained in (B) and (C) to the number of amino groups contained in (A), 0.3 to 0.97 A range is preferred. When the ratio is less than 0.3, a sufficient amount of amide groups is not generated in the epoxy resin curing agent, and a high level of gas barrier properties and adhesion to various film materials is not exhibited. Further, the proportion of volatile molecules remaining in the epoxy resin curing agent increases, which causes odor generation from the obtained cured product. In addition, since the ratio of hydroxyl groups generated by the reaction between the epoxy groups and the amino groups in the cured product increases, the oxygen barrier property under a high humidity environment is significantly reduced. On the other hand, in the range higher than 0.97, the amount of the amino group which reacts with the epoxy resin is reduced, so that excellent impact resistance and heat resistance are not exhibited, and the solubility in various organic solvents or water is reduced. When particularly considering the high gas barrier property of the obtained cured product, high adhesion, suppression of odor generation and high oxygen barrier property under a high humidity environment, the molar ratio of the polyfunctional compound to the polyamine component is 0.6. The range of -0.97 is more preferable. Taking into account the development of higher levels of adhesion to various film materials, the epoxy resin curing agent of the present invention contains at least 6% by weight of amide groups based on the total weight of the curing agent. Is preferred. The reaction with (A) and (B), or (A), (B), and (C) varies depending on each compound, but proceeds at 140 to 230 ° C., and water or carboxylic acid or ester-derived water or It is desirable to distill off the alcohol. The properties of the obtained product vary depending on the molecular weight and the number of functional groups of (A), (B) and (C), and the viscosity is from 10 mPa · s / 25 ° C. to a solid. May be added.

  The laminated film produced using the laminating adhesive of the present invention has an initial adhesive force between the film materials of 30 g / 15 mm or more when T-peeled at a peeling speed of 300 mm / min immediately after lamination. It is more preferably 40 g / 15 mm or more, and particularly preferably 50 g / 15 mm or more. If the adhesiveness is not sufficient, problems such as tunneling of the laminated film and misalignment when winding the film occur.

In consideration of the development of high tackiness, at least one of amide group sites and oligomers can be formed by reacting an epoxy resin curing agent such as meta-xylylenediamine or para-xylylenediamine with the polyamine. The reaction ratio of the reaction product with the polyfunctional compound having two acyl groups is 0.6 to 0.97, preferably 0.8 to 0.97, particularly preferably 0.8 to 0.9 in molar ratio of the polyfunctional compound to the polyamine component. Is in the range of 0.85 to 0.97, and it is preferable to use an epoxy resin curing agent in which the average molecular weight of the oligomer as a reaction product is increased.
A more preferred epoxy resin curing agent is the reaction product of meta-xylylenediamine with acrylic acid, methacrylic acid and / or their derivatives. Here, the reaction molar ratio of acrylic acid, methacrylic acid and / or a derivative thereof to meta-xylylenediamine is preferably in the range of 0.8 to 0.97.

The mixing ratio of the epoxy resin and the epoxy resin curing agent, which are the main components of the laminating adhesive in the storage method of the present invention, is generally a standard for preparing an epoxy resin cured product by the reaction between the epoxy resin and the epoxy resin curing agent. May be in a typical compounding range. Specifically, the ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin (active hydrogen / epoxy group) is in the range of 0.5 to 5.0. In the range of less than 0.5, the remaining unreacted epoxy groups cause the gas barrier property of the obtained cured product to decrease, and in the range of more than 5.0, the remaining unreacted amino groups cause the obtained cured product. Causes a decrease in wet heat resistance. When the gas barrier property and wet heat resistance of the obtained cured product are particularly considered, the range is more preferably from 0.8 to 3.0, and particularly preferably from 0.8 to 1.4.
In addition, when considering the development of high oxygen barrier properties of the obtained cured product in a high humidity environment, the ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin is 0.8. The range of -1.4 is preferable.

  In the present invention, the laminating adhesive may be, if necessary, a thermosetting polyurethane resin composition, a polyacrylic resin composition, a polyurea resin composition, or the like, as long as the effects of the present invention are not impaired. You may mix a hydrophilic resin composition.

  If necessary, a wetting agent such as silicon or an acrylic compound may be added to the laminating adhesive in the preservation method of the present invention in order to assist the wetting of the surface during application to various film materials. Suitable wetting agents include BYK331, BYK333, BYK348, BYK381, BYK380N available from Big Chemie. When these are added, the content is preferably in the range of 0.01% by weight to 2.0% by weight based on the total weight of the laminating adhesive.

  The laminating adhesive in the storage method of the present invention is provided with a tackifier such as a xylene resin, a terpene resin, a phenol resin, or a rosin resin, as needed, in order to improve the tackiness to various film materials immediately after being applied to the various film materials. An agent may be added. When these are added, the range is preferably 0.01% by weight to 5.0% by weight based on the total weight of the laminating adhesive.

Further, in order to improve various properties such as gas barrier properties, impact resistance and heat resistance of the adhesive layer formed by the laminating adhesive in the storage method of the present invention, silica, alumina, and mica are included in the laminating adhesive. , Talc, aluminum flakes, glass flakes and other inorganic fillers may be added.
In consideration of the transparency of the film, it is preferable that such an inorganic filler has a flat plate shape. When these are added, the range is preferably 0.01% by weight to 10.0% by weight based on the total weight of the laminating adhesive.

  Further, a compound having an oxygen-scavenging function or the like may be added to the laminating adhesive in the storage method of the present invention, if necessary. Examples of the compound having an oxygen scavenging function include, for example, hindered phenols, vitamin C, vitamin E, organic phosphorus compounds, gallic acid, low molecular weight organic compounds that react with oxygen such as pyrogallol, and cobalt, manganese, nickel, iron, Transition metal compounds such as copper are exemplified.

  Further, in order to improve the adhesiveness of the adhesive layer formed by the adhesive for lamination in the storage method of the present invention to various film materials such as thermoplastic resin films, metal foils, and paper, silane is contained in the adhesive for lamination. A coupling agent such as a coupling agent or a titanium coupling agent may be added. When these are added, the range is preferably 0.01% by weight to 10.0% by weight based on the total weight of the laminating adhesive.

  When various film materials are laminated using the laminating adhesive in the storage method of the present invention, a known laminating method such as dry lamination, non-solvent lamination, and extrusion lamination can be used.

  When applying the laminating adhesive in the storage method of the present invention to a film material and laminating, the lamination is performed at a concentration and temperature of the epoxy resin composition sufficient to obtain an epoxy resin cured product to be an adhesive layer. This can vary with the choice of starting material and lamination method. That is, the concentration of the epoxy resin composition is about 5% by weight using a suitable organic solvent and / or water from a case where no solvent is used, depending on the kind and molar ratio of the selected material, a lamination method, and the like. Various states can be taken up to the case of dilution to the composition concentration. Suitable organic solvents include water-insoluble solvents such as toluene, xylene and ethyl acetate, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1 Glycol ethers such as -ethoxy-2-propanol and 1-propoxy-2-propanol, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-butanol, N, N-dimethylformamide And aprotic polar solvents such as N, N-dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone, and relatively low-boiling solvents such as methanol, ethyl acetate and 2-propanol are preferred. When a solvent is used, the drying temperature of the solvent after coating may vary from room temperature to about 140 ° C. As a coating method for applying the laminating adhesive to the polymer film, any of commonly used coating methods such as roll coating, spray coating, air knife coating, dipping, and brushing can be used. Roll coating or spray coating is preferred. For example, the same roll coating or spray technique and equipment as in the case of applying and laminating a polyurethane adhesive component on a polymer film can be applied.

  Subsequently, a specific operation in each lamination method will be described. In the case of the dry lamination method, a diluting solution of the laminating adhesive of the present invention with an organic solvent and / or water is applied to a film material serving as a substrate by a roll such as a gravure roll, and then the solvent is dried and immediately applied to the surface thereof. By laminating a new film material, a laminated film can be obtained. In this case, it is desirable that aging is performed at room temperature to 60 ° C. for a certain period of time as needed after lamination to complete the curing reaction. By performing aging for a certain period of time, an epoxy resin cured reactant is formed at a sufficient reaction rate, and high gas barrier properties are exhibited.

  In the case of the non-solvent laminating method, a gravure roll heated to 40 ° C. to 120 ° C. with the laminating adhesive of the present invention previously heated to about 40 ° C. to 100 ° C. on a film material serving as a base material is used. Immediately after coating with a roll, a new film material is stuck to the surface to obtain a laminated film. Also in this case, it is desirable to perform aging for a certain period of time as needed after lamination as in the case of the dry lamination method.

In the case of the extrusion lamination method, an organic solvent and / or an epoxy resin and an epoxy resin curing agent, which are main components of the laminating adhesive of the present invention, are used as an adhesion auxiliary agent (anchor coating agent) for a film material as a base material. Is applied by a roll such as a gravure roll, the solvent is dried and cured at room temperature to 140 ° C., and then a polymer material melted by an extruder is laminated to obtain a laminated film. As the polymer material to be melted, polyolefin resins such as low-density polyethylene resin, linear low-density polyethylene resin, and ethylene-vinyl acetate copolymer resin are preferable.
These laminating methods and other commonly used laminating methods can be combined as necessary, and the layer structure of the laminated film can be changed depending on the application and form.

  The thickness of the adhesive layer after applying the laminating adhesive in the storage method of the present invention to various film materials and the like, drying, bonding, and heat treatment is practically 0.1 to 100 μm, preferably 0.5 to 10 μm. is there. If it is less than 0.1 μm, it is difficult to exhibit sufficient gas barrier properties and adhesiveness, while if it exceeds 100 μm, it becomes difficult to form an adhesive layer having a uniform thickness.

  The laminating adhesive in the storage method of the present invention is characterized by having a high gas barrier property in addition to a suitable adhesive property to various film materials, and exhibits a high gas barrier property in a wide range from low humidity conditions to high humidity conditions. . From this, the laminated film using the adhesive is a PVDC coat layer, a polyvinyl alcohol (PVA) coat layer, an ethylene-vinyl alcohol copolymer (EVOH) film layer, a meta-xylylene adipamide film layer, an alumina or A very high level of gas barrier property is exhibited without using a commonly used gas barrier material such as an inorganic vapor-deposited film layer on which silica or the like is vapor-deposited. Furthermore, by using these conventional gas barrier materials and other thermoplastic resin layers together as an adhesive for bonding, the resulting film can have significantly improved gas barrier properties.

  Gas barriers such as ethylene-vinyl alcohol copolymer (EVOH) -based films, polyvinyl alcohol-based films, polyvinyl alcohol-coated films, polyvinyl alcohol-coated films with inorganic fillers dispersed, and meta-xylene adipamide (N-MXD6) films However, when the adhesive film is used to form a laminated film containing these gas barrier films, this disadvantage can be solved. it can.

  Furthermore, the cured epoxy resin forming the adhesive layer in the gas barrier laminate film in the storage method of the present invention is excellent in toughness, wet heat resistance, impact resistance, boiling resistance, retort resistance, and the like. The resulting gas barrier laminated film is obtained.

  When a food is stored using the gas-barrier laminated film in the storage method of the present invention, the use state may vary depending on the type of the contents, the use environment, and the use form. That is, the laminated film can be used as it is as a multilayer packaging material, or an oxygen-absorbing layer or a thermoplastic resin film layer, a paper layer, a metal foil layer, and the like can be further laminated on the laminated film as needed. . At this time, the layers may be laminated using the laminating adhesive in the storage method of the present invention, or may be laminated using another adhesive or an anchor coat agent.

  A conventionally known method can be used as a method of storing food using a multilayer packaging material, but a method of using a multilayer packaging material to form a packaging bag and filling the food therein is common. It is. The packaging bag can be manufactured by using a multilayer packaging material, overlapping the surfaces of the heat-sealable resin layers facing each other, and then heat-sealing the peripheral edge to form a seal portion. . As the bag making method, for example, the above-mentioned multilayer packaging material is bent or overlapped, the surfaces of its inner layers are opposed to each other, and the peripheral end thereof is further sealed, for example, a side seal type, a two-side seal type, a three-side seal type. , Four-sided seal type, envelope-attached seal type, gasket-attached seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, gusset type, etc. Can be The packaging bag can take various forms depending on the contents, the use environment, and the use form. In addition, for example, a self-supporting packaging bag (standing pouch) can be used. As a heat sealing method, for example, a known method such as a bar seal, a rotary roll seal, a belt seal, an impulse seal, a high frequency seal, an ultrasonic seal, or the like can be used.

A packaged product can be manufactured by filling the contents into the packaging bag through the opening and then heat-sealing the opening. As the filling method, a known method such as an aerated filling method or a gas replacement filling method with nitrogen or the like can be applied. At that time, the oxygen concentration is 1% or less, preferably 0.5% or less, more preferably 0.2% or less. If necessary, a material having a deoxygenating function can also be put in the packaging bag.
Foods to which the storage method of the present invention can be applied include a wide range from dry foods having a water activity value of about 0.1 to semi-raw foods, raw foods, and liquid foods having a water activity value of about 0.95. Specifically, bread, snack noodles, instant noodles, dried noodles, pasta, aseptic packaged rice, porridge, rice porridge, packaging sticky, staples such as cereal foods, rice confectionery, beans, nuts, snacks, candy, chocolate, Biscuits, cookies, wafer confectionery, castella, marshmallow, pies, buns, yokan, half-baked cakes and other sweets, hams, bacon, sausages, chicken processed products, livestock processed products such as corn beef, fish meat ham and sausages , Fishery products, kamaboko, glue, boiled tsukudani, bonito, salted fish, smoked salmon, spicy mentaiko, tororo kelp, curry, liquid soup, boiled food, stew, vinegar, soy sauce, sauce, miso, etc. , But not limited thereto.

  The gas barrier laminate film in the storage method of the present invention uses a laminating adhesive containing an epoxy resin composition having a high gas barrier property as a main component as a substantial gas barrier material. Various gas barrier properties such as oxygen, water vapor, and aroma components in a wide range of conditions, and their lamination strength, heat sealability, heat resistance, moisture resistance, acid resistance, oil resistance, transparency, environmental compatibility, economy, etc. In addition, it does not cause discoloration of the laminated film after the boil treatment or decrease in the lamination strength after storage. By using the gas-barrier laminated film of the present invention and the packaging bag obtained by producing the laminated film, foods are sufficiently protected, and their storage and storage stability, filling and packaging suitability, and environmental suitability are ensured. In addition, it is possible to provide a storage method which is excellent in economy and the like.

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

The method for measuring the initial adhesive strength of the laminated film is as follows.
<Method of measuring initial adhesive strength>
The film immediately after lamination was cut into a strip having a length of 300 mm and a width of 15 mm, used as a test piece, and subjected to T-type peeling at a peeling rate of 300 mm / min by using a method specified in JIS K-6854.

<Epoxy resin curing agent a>
A reaction vessel was charged with 1 mole of metaxylylenediamine. The temperature was raised to 60 ° C. in a nitrogen stream, and 0.93 mol of methyl acrylate was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was stirred at 120 ° C. for 1 hour, and further heated to 160 ° C. in 3 hours while distilling off generated methanol. After cooling to 100 ° C., a predetermined amount of methanol was added so that the solid content concentration became 70% by weight, to obtain an epoxy resin curing agent a. The amide group content in the epoxy resin curing agent a was 21% by weight.

<Laminated film A>
Methanol / ethyl acetate = 7 / containing 50 parts by weight of an epoxy resin having a glycidylamine moiety derived from meta-xylylenediamine (manufactured by Mitsubishi Gas Chemical Co., Ltd .; TETRAD-X) and 146 parts by weight of an epoxy resin curing agent a Three solutions (solid content: 35% by weight) were prepared, and 0.4 parts by weight of an acrylic wetting agent (manufactured by BYK-Chemie; BYK381) was added thereto and stirred well to obtain a coating solution.
This coating solution was applied to a stretched polypropylene film having a thickness of 20 μm using a bar coater No. 6 (coating amount: 3.5 g / m ² (solid content)), dried at 85 ° C. for 10 seconds, and then dried. A 40 μm non-stretched polypropylene film was adhered by a nip roll, and aged at 40 ° C. for 4 days to obtain a laminated film A. The initial adhesive strength was 70 g / 15 mm, and the content of the skeleton structure of the formula (1) in the adhesive layer (cured epoxy resin) was 62.0% by weight.

<Laminated film B>
The same as the laminated film A except that a stretched nylon film having a thickness of 15 μm was used instead of the stretched polypropylene film having a thickness of 20 μm, and a linear low-density polyethylene film having a thickness of 40 μm was used instead of the unstretched polypropylene film having a thickness of 40 μm. To obtain a laminated film B. The initial tack was 70 g / 15 mm.

<Laminated film C>
Instead of the stretched polypropylene film having a thickness of 20 μm, a polyethylene terephthalate film having a thickness of 12 μm was used, and instead of the unstretched polypropylene film having a thickness of 40 μm, the same as the laminated film A except that a linear low-density polyethylene film having a thickness of 40 μm was used. To obtain a laminated film C. The initial tack was 90 g / 15 mm.

<Laminated film D>
Laminated film D was obtained in the same manner as for laminated film A, except that a linear low-density polyethylene film having a thickness of 40 μm was used instead of the unstretched polypropylene film having a thickness of 40 μm. The initial tack was 70 g / 15 mm.

<Laminated film E>
The same as the laminated film A except that a stretched nylon film having a thickness of 15 μm was used instead of the stretched polypropylene film having a thickness of 20 μm, and a linear low-density polyethylene film having a thickness of 40 μm was used instead of the unstretched polypropylene film having a thickness of 40 μm. To obtain a laminated film E. The initial tack was 90 g / 15 mm.

<Laminated film F>
A laminated film F was obtained in the same manner as for the laminated film A, except that a stretched nylon film having a thickness of 15 μm was used instead of the stretched polypropylene film having a thickness of 20 μm. The initial tack was 90 g / 15 mm.

<Example 1>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. From the opening of the three-side sealed type packaging bag, bread is filled with nitrogen gas so as to have an oxygen concentration of 1%, and the opening is heat-sealed to form an upper seal portion. Was manufactured.

<Example 2>
Two laminated films B are prepared, the linear low-density polyethylene films are superposed on each other with their surfaces facing each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. In the manufactured three-side sealed type packaging bag, the half-life ramen is filled with nitrogen gas from its opening so as to have an oxygen concentration of 1%, and the opening is heat-sealed to form an upper sealing portion. Manufactured product.

<Example 3>
Two laminated films C are prepared, the surfaces of the linear low-density polyethylene films are superimposed on each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. In the manufactured three-side sealed type packaging bag, the half-life ramen is filled with nitrogen gas from its opening so as to have an oxygen concentration of 1%, and the opening is heat-sealed to form an upper sealing portion. Manufactured product.

<Example 4>
Two laminated films B are prepared, the linear low-density polyethylene films are superposed on each other with their surfaces facing each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. In the manufactured three-side seal type packaging bag, the moist is filled and packed from the opening, and a deoxidizer (manufactured by Mitsubishi Gas Chemical Co., Ltd .; Ageless) is put in, and the opening is heat-sealed and sealed upward. A packaged product was manufactured by forming a part.

<Example 5>
Two laminated films C are prepared, the surfaces of the linear low-density polyethylene films are superimposed on each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. In the manufactured three-side seal type packaging bag, the rice cake is filled and sealed from its opening, and a deoxidizer (Mitsubishi Gas Chemical Co., Ltd .; Ageless) is put in, and the opening is heat-sealed and sealed upward. A packaged product was manufactured by forming a part.

<Example 6>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. Butter peanuts are filled with nitrogen gas from the opening of the three-side sealed type packaging bag so as to have an oxygen concentration of 1%, and the opening is heat-sealed to form an upper sealing portion. Manufactured product.

<Example 7>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. Butter peanuts are filled and packaged from the opening in the manufactured three-side seal type packaging bag, an oxygen scavenger (Mitsubishi Gas Chemical Co., Ltd .; Ageless) is put in, and the opening is heat-sealed and A packaged product was manufactured by forming a seal portion.

Example 8
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. In the manufactured three-side seal type packaging bag, the financier is filled with nitrogen gas from its opening so as to have an oxygen concentration of 1%, and the opening is heat-sealed to form an upper sealing portion, thereby forming a packaged product. Was manufactured.

<Example 9>
Two laminated films B are prepared, the linear low-density polyethylene films are superposed on each other with their surfaces facing each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. In the manufactured three-side seal type packaging bag, the castella is filled with nitrogen gas from its opening so as to have an oxygen concentration of 1%, and the opening is heat-sealed to form an upper sealing portion, thereby forming a packaged product. Was manufactured.

<Example 10>
Two laminated films C are prepared, the surfaces of the linear low-density polyethylene films are superimposed on each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. In the manufactured three-side seal type packaging bag, the castella is filled with nitrogen gas from its opening so as to have an oxygen concentration of 1%, and the opening is heat-sealed to form an upper sealing portion, thereby forming a packaged product. Was manufactured.

<Example 11>
Two laminated films D are prepared, the linear low-density polyethylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat-sealed three-way to form a seal portion. A sealed packaging bag was manufactured. From the opening, the sliced ham is filled with nitrogen gas so as to have an oxygen concentration of 1% in the manufactured three-side seal type packaging bag, and the opening is heat-sealed to form an upper seal portion. Manufactured product.

<Example 12>
Two laminated films D are prepared, the linear low-density polyethylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat-sealed three-way to form a seal portion. A sealed packaging bag was manufactured. From the opening, the sliced ham is filled with nitrogen gas so as to have an oxygen concentration of 0.1% or less in the manufactured three-side seal type packaging bag, and the opening is heat-sealed to form an upper seal portion. This produced a packaged product.

<Example 13>
Two laminated films D are prepared, the linear low-density polyethylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat-sealed three-way to form a seal portion. A sealed packaging bag was manufactured. The sliced ham is filled and packaged from the opening in the manufactured three-side seal type packaging bag, an oxygen scavenger (manufactured by Mitsubishi Gas Chemical Co., Ltd .; Ageless) is put in, and the opening is heat-sealed and upward. A packaged product was manufactured by forming a seal portion.

<Example 14>
Two laminated films E are prepared, the surfaces of the linear low-density polyethylene films are superimposed on each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. In the manufactured three-side seal type packaging bag, the melted kelp is filled with nitrogen gas through the opening so that the oxygen concentration is 0.1% or less, and the opening is heat-sealed to form an upper seal portion. This produced a packaged product.

<Example 15>
Two laminated films E are prepared, the surfaces of the linear low-density polyethylene films are superimposed on each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. In the manufactured three-side seal type packaging bag, fill and package the tororo kelp from the opening, put an oxygen scavenger (Mitsubishi Gas Chemical Co., Ltd .; Ageless), heat seal the opening, and A packaged product was manufactured by forming a seal portion.

  After packaging, the buttered peanut packaged product was left in a 30 ° C non-humidified thermostat, and the oxygen concentration in the bag was measured by gas chromatography to determine the peroxide value (POV) and acid value of the content food. (AV) and sensory evaluation were performed. The bread, the financier, the half-boiled ramen, and the castella packaged product were allowed to stand in a room at 25 ° C., and then the oxygen concentration in the bag was measured by gas chromatography, and the sensory evaluation of the content food was performed. After leaving the sliced ham package in a refrigerated open showcase (about 10 ° C, under 4000 lux fluorescent light), measure the oxygen concentration in the bag by gas chromatography and measure the number of general viable bacteria and yeast in the content food. And a sensory evaluation was performed. The tororo kelp was left under a 1000 lux fluorescent lamp in a room at 25 ° C., and then the oxygen concentration in the bag was measured by gas chromatography, and the sensory evaluation of the content food was performed. The results are shown in Table 1-8.

  The method of measuring the peroxide value (POV) and the acid value (AV), the number of general viable bacteria, the number of yeasts, and the sensory evaluation are as follows.

<Peroxide value (POV)>
After pulverizing the food in the packaged product, diatomaceous earth and an appropriate amount of methylene chloride / methanol (2/1; vol) are added, and the mixture is allowed to stand at room temperature in a dark room for about 15 hours. After filtration, after distilling off the solvent, dissolving in methylene chloride and acetic acid, adding a saturated potassium iodide aqueous solution, and then using an automatic titrator APB-10 manufactured by Kyoto Electronics Co., Ltd. using a sodium thiosulfate aqueous solution as a titrant. , The peroxide value (POV) was measured.

<Acid value (AV)>
After pulverizing the food in the packaged product, an appropriate amount of diatomaceous earth and a methylene chloride / methanol mixture are added, and the mixture is allowed to stand at room temperature in a dark room for about 15 hours. After filtration, the solvent was distilled off, the residue was dissolved in a methylene chloride / methanol mixture, and the acid value (AV) was determined by an automatic titrator APB-10 manufactured by Kyoto Electronics Co., Ltd. using a sodium thiosulfate aqueous solution as a titrant. Was measured.

<General bacteria count>
Sterile physiological saline is added to the appropriate amount of food in the bag, mixed and diluted, poured into a standard agar medium for bacteria, cultured at 35 ° C. for 48 hours, the number of colonies is counted, and the number of bacteria per gram of food is calculated.

<Yeast count>
Sterile physiological saline is added to the appropriate amount of food in the bag, mixed and diluted, poured into a potato dextrose agar medium containing 0.01% chloramphenicol for yeast and mold culture, cultured at 25 ° C for 96 hours, and the number of colonies is counted. Calculate the number of bacteria per gram of food.

<Appearance>
The appearance of the food is observed and evaluated in three steps.
○: No change in appearance △: There is fading ×: There is significant fading

<Smell / taste>
The odor and taste of food are evaluated on a five-point scale.
5: Both smell and taste are good 4: Both smell and taste are slightly reduced 3: Both smell and taste are reduced 2: Slight odor (rot odor, oxidation odor, altered odor, packaging odor, fermentation odor) 1: Notable odor (rot) Odor, oxidation odor, altered odor, packaging odor, fermentation odor)

Note 1: Initial POV 0.7 meq / kg
Note 2: Initial AV 0.5 mgKOH / g

Note 1: Initial general viable cell count 30 cfu / g
Note 2: Initial yeast count 300 cfu / g

  As is clear from the test results shown in the above Tables 1-8, the present invention is a method for preserving food without changing the flavor and odor.

The method for evaluating the lamination strength of the laminated film is as follows.
<Lamination strength (g / 15mm)>
Using the method specified in JIS K-6854, the lamination strength of the laminated film was measured at a peel speed of 100 mm / min by a T-type peel test.
<Discoloration after boiling>
The film was compared with the laminated film before the boiling treatment, and visually judged.

<Reference Example 1>
The laminate strength of the laminated film A was evaluated. Table 9 shows the results.

<Reference Example 2>
After the laminated film A was boiled at 90 ° C. for 30 minutes, discoloration and laminate strength were evaluated. Table 9 shows the results.

<Example 16>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of water is filled into the manufactured three-side seal type packaging bag through the opening, and the head space is sealed so that the air becomes zero. Then, the bag is stored under the condition of 23 ° C./60% RH for one month, and discolored. And the laminate strength was evaluated. Table 9 shows the results.

<Example 17>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of water is filled from the opening into the manufactured three-side seal type packaging bag, the headspace air is sealed so that the air becomes 0, boiled at 90 ° C./30 minutes, and then 23 ° C./60% It was stored for one month under the condition of RH, and the discoloration and the laminate strength were evaluated. Table 9 shows the results.

<Example 18>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of water was filled from the opening into the manufactured three-side seal type packaging bag, the head space was sealed so that the air became 0, and then stored for one month under the condition of immersion in hot water at 40 ° C., discoloration and lamination. The strength was evaluated. Table 9 shows the results.

<Example 19>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of water is filled into the manufactured three-side seal type packaging bag from the opening, the headspace air is sealed so that the air becomes zero, boiled at 90 ° C. for 30 minutes, and then immersed in hot water at 40 ° C. After storage under the conditions for one month, discoloration and laminate strength were evaluated. Table 9 shows the results.

<Example 20>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of a 3% by weight aqueous acetic acid solution is filled into the manufactured three-side seal type packaging bag from the opening, sealed so that the headspace air becomes zero, boiled at 90 ° C. for 30 minutes, and then discolored. And the laminate strength was evaluated. Table 9 shows the results.

<Example 21>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of a 3% by weight acetic acid aqueous solution is filled into the manufactured three-side seal type packaging bag from the opening thereof, and the headspace air is sealed so that the air becomes zero. It was stored and evaluated for discoloration and laminate strength. Table 9 shows the results.

<Example 22>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of a 3 wt% acetic acid aqueous solution was filled into the manufactured three-side seal type packaging bag from the opening thereof, the head space air was sealed so that the air became 0, and after boil treatment at 90 ° C./30 minutes, 23 It was stored for one month under the conditions of ° C / 60% RH, and the discoloration and the lamination strength were evaluated. Table 9 shows the results.

<Example 23>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of a 3% by weight acetic acid aqueous solution was filled into the manufactured three-side seal type packaging bag from the opening thereof, and the headspace was sealed so that the air in the space was reduced to zero. , Discoloration and laminate strength were evaluated. Table 9 shows the results.

<Example 24>
Two laminated films A were prepared, the unstretched polypropylene films were superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge was heat sealed three-way to form a seal portion, and a three-side seal type having an opening above was formed. A packaging bag was manufactured. 200 g of a 3 wt% acetic acid aqueous solution was filled into the manufactured three-side seal type packaging bag from the opening, sealed so that the headspace air became 0, and subjected to boil treatment at 90 ° C./30 minutes. It was stored for one month under the condition of immersion in hot water at ℃, and the discoloration and the laminate strength were evaluated. Table 9 shows the results.

<Reference Example 3>
The laminate strength of the laminated film F was evaluated. Table 10 shows the results.

<Reference example 4>
After the laminated film F was boiled at 90 ° C. for 30 minutes, discoloration and laminate strength were evaluated. Table 10 shows the results.

<Example 25>
Two laminated films F are prepared, the unstretched polypropylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat sealed three-way to form a seal portion. A packaging bag was manufactured. 200 g of water is filled into the manufactured three-side seal type packaging bag through the opening, and the head space is sealed so that the air becomes zero. Then, the bag is stored under the condition of 23 ° C./60% RH for one month, and discolored. And the laminate strength was evaluated. Table 10 shows the results.

<Example 26>
Two laminated films F are prepared, the unstretched polypropylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat sealed three-way to form a seal portion. A packaging bag was manufactured. 200 g of water is filled from the opening into the manufactured three-side seal type packaging bag, the headspace air is sealed so that the air becomes 0, boiled at 90 ° C./30 minutes, and then 23 ° C./60% It was stored for one month under the condition of RH, and the discoloration and the laminate strength were evaluated. Table 10 shows the results.

<Example 27>
Two laminated films F are prepared, the unstretched polypropylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat sealed three-way to form a seal portion. A packaging bag was manufactured. 200 g of water was filled from the opening into the manufactured three-side seal type packaging bag, the head space was sealed so that the air became 0, and then stored for one month under the condition of immersion in hot water at 40 ° C., discoloration and lamination. The strength was evaluated. Table 10 shows the results.

<Example 28>
Two laminated films F are prepared, the unstretched polypropylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat sealed three-way to form a seal portion. A packaging bag was manufactured. 200 g of water is filled into the manufactured three-side seal type packaging bag from the opening, the headspace air is sealed so that the air becomes zero, boiled at 90 ° C. for 30 minutes, and then immersed in hot water at 40 ° C. After storage under the conditions for one month, discoloration and laminate strength were evaluated. Table 10 shows the results.

<Example 29>
Two laminated films F are prepared, the unstretched polypropylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat sealed three-way to form a seal portion. A packaging bag was manufactured. 200 g of a 3% by weight aqueous acetic acid solution is filled into the manufactured three-side seal type packaging bag from the opening, sealed so that the headspace air becomes zero, boiled at 90 ° C. for 30 minutes, and then discolored. And the laminate strength was evaluated. Table 10 shows the results.

<Example 30>
Two laminated films F are prepared, and the unstretched polypropylene film is superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat-sealed on three sides to form a seal portion. A sealed packaging bag was manufactured. 200 g of a 3% by weight acetic acid aqueous solution is filled into the manufactured three-side seal type packaging bag from the opening thereof, and the headspace air is sealed so that the air becomes zero. It was stored and evaluated for discoloration and laminate strength. Table 10 shows the results.

<Example 31>
Two laminated films F are prepared, the unstretched polypropylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat sealed three-way to form a seal portion. A packaging bag was manufactured. 200 g of a 3 wt% acetic acid aqueous solution was filled into the manufactured three-side seal type packaging bag from the opening thereof, the head space air was sealed so that the air became 0, and after boil treatment at 90 ° C./30 minutes, 23 It was stored for one month under the conditions of ° C / 60% RH, and the discoloration and the lamination strength were evaluated. Table 10 shows the results.

<Example 32>
Two laminated films F are prepared, the unstretched polypropylene films are superimposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat sealed three-way to form a seal portion, and a three-side seal type having an opening at the top is formed. A packaging bag was manufactured. 200 g of a 3% by weight acetic acid aqueous solution was filled into the manufactured three-side seal type packaging bag from the opening thereof, and the headspace was sealed so that the air in the space was reduced to zero. , Discoloration and laminate strength were evaluated. Table 10 shows the results.

<Example 33>
Two laminated films F are prepared, the unstretched polypropylene films are superposed on each other with the surfaces thereof facing each other, and the outer peripheral edge is heat sealed three-way to form a seal portion. A packaging bag was manufactured. 200 g of a 3 wt% acetic acid aqueous solution was filled into the manufactured three-side seal type packaging bag from the opening, sealed so that the headspace air became 0, and subjected to boil treatment at 90 ° C./30 minutes. It was stored for one month under the condition of immersion in hot water at ℃, and the discoloration and the laminate strength were evaluated. Table 10 shows the results.

  As is clear from the test results shown in Tables 9 and 10, the present invention does not cause discoloration of the laminated film after the boil treatment even if the content is any of water and 3% by weight acetic acid, and the packaging maintains good lamination strength. This is a method for preserving a liquid food for a long time by using a bag.

Claims (14)

Food using a gas-barrier laminated film including an outer layer made of a thermoplastic resin, an inner layer made of a thermoplastic resin having heat sealing properties, and an adhesive layer formed using an adhesive for lamination containing an epoxy resin composition as a main component A method for preserving food, wherein the cured epoxy resin formed from the epoxy resin composition contains 40% by weight or more of the skeleton structure of the formula (1).
The storage method according to claim 1, wherein the food is any one of staples, confectionery, processed livestock products, processed marine products, and liquid foods. The epoxy resin composition comprises an epoxy resin and an epoxy resin curing agent, and the ratio of active hydrogen in the epoxy resin curing agent to epoxy groups in the epoxy resin (active hydrogen / epoxy group) is 0.8 to 1.4. The storage method according to claim 1, wherein the storage method is a range. Epoxy resin having glycidylamine moiety derived from meta-xylylenediamine, epoxy resin having glycidylamine moiety derived from 1,3-bis (aminomethyl) cyclohexane, glycidylamine moiety derived from diaminodiphenylmethane An epoxy resin having a glycidylamine moiety and / or a glycidyl ether moiety derived from para-aminophenol, an epoxy resin having a glycidyl ether moiety derived from bisphenol A, and a glycidyl ether moiety derived from bisphenol F Epoxy resin, epoxy resin having glycidyl ether moiety derived from phenol novolak, and epoxy resin having glycidyl ether moiety derived from resorcinol The storage method according to claim 3, wherein the storage method is at least one member selected from the group consisting of oxy resins. The storage method according to claim 3, wherein the epoxy resin is mainly composed of an epoxy resin having a glycidylamine moiety derived from meta-xylylenediamine and / or an epoxy resin having a glycidyl ether moiety derived from bisphenol F. The storage method according to claim 3, wherein the epoxy resin is mainly composed of an epoxy resin having a glycidylamine moiety derived from meta-xylylenediamine. The storage method according to claim 3, wherein the epoxy resin curing agent is a reaction product of the following (A) and (B) or a reaction product of (A), (B) and (C).
(A) meta-xylylenediamine or para-xylylenediamine
(B) a polyfunctional compound having at least one acyl group capable of forming an amide group site by reaction with a polyamine to form an oligomer
(C) a monovalent carboxylic acid having 1 to 8 carbon atoms and / or a derivative thereof The reaction molar ratio of (A) and (B) or (A), (B), and (C) is such that the reactive functionality contained in (B) with respect to the number of amino groups contained in (A), respectively. The ratio of the number of groups or the ratio of the total number of reactive functional groups contained in (B) and (C) to the number of amino groups contained in (A) is in the range of 0.6 to 0.97. The storage method according to claim 7, wherein The storage method according to claim 3, wherein the epoxy resin curing agent is a reaction product of meta-xylylenediamine with acrylic acid, methacrylic acid and / or a derivative thereof. The storage method according to claim 7, wherein the reaction molar ratio of acrylic acid, methacrylic acid and / or a derivative thereof to m-xylylenediamine is in the range of 0.8 to 0.97. 4. The method according to claim 3, wherein the epoxy resin curing agent contains at least 6% by weight of amide groups based on the total weight of the curing agent. The storage method according to any one of claims 1 to 11, wherein the initial adhesive force between the laminated films is 30 g / 15 mm or more when T-peeling is performed at a peeling speed of 300 mm / min immediately after lamination. The storage method according to any one of claims 1 to 12, wherein the outer layer is a biaxially oriented polyolefin resin film, a biaxially oriented polyester resin film, or a biaxially oriented polyamide resin film. The storage method according to any one of claims 1 to 13, wherein the inner layer is a polyolefin-based resin layer.