JP7255141B2 - Laminates, packages and packaged articles - Google Patents

Description

TECHNICAL FIELD The present invention relates to laminates, packages and packaged articles.

Oxygen present in the packaging of food may oxidize the food and the like, which may cause deterioration or discoloration. In order to prevent oxidative deterioration of the packaged contents, it is effective to remove oxygen from the package and to create an oxygen-free state by blocking external oxygen from entering the package.

However, since the packaging operation is generally performed in the atmosphere, oxygen remains in the package during packaging. In order to solve this problem, deaeration packaging, vacuum packaging, gas exchange packaging, and the like are sometimes used as means for packaging so that oxygen does not remain in the package.

However, the use of such a special packaging means requires the preparation of special filling and packaging equipment, which is disadvantageous in that the equipment costs are high, and the filling and packaging speed does not increase, resulting in a decrease in production efficiency. occurs. In addition, even if the packaging is carried out so that no oxygen remains during packaging, it is difficult to maintain the inside of the package in an oxygen-free state because oxygen from the outside enters through the packaging material over time after packaging. .

Therefore, as a means for removing oxygen remaining in the package and oxygen entering from the outside over time after packaging, an oxygen scavenger consisting of a small bag filled with an oxygen-absorbing substance is filled in the package containing the contents. method is used. In this method, oxygen can be removed by the oxygen-absorbing chemical absorbing oxygen for a certain period of time, ie, the period during which the oxygen-absorbing ability of the oxygen-absorbing chemical is maintained. Therefore, it is possible to remove oxygen remaining in the package during packaging and oxygen that has entered from the outside over time, which is very effective in maintaining the inside of the package in an oxygen-free state. However, oxygen scavengers are troublesome and costly when filling oxygen-absorbing chemicals. In addition, there are problems such as accidental ingestion by consumers and generation of waste.

As a means to eliminate such drawbacks and to remove and block oxygen in the package for a certain period of time, an oxygen-absorbing film in which a part of the film constituting the packaging material is provided with an oxygen-absorbing function, or an oxygen-absorbing film using such an oxygen-absorbing film. A packaging material has been devised and partially put into practical use.

At present, oxygen-absorbing packaging materials such as those described above are often used in the food packaging field, especially for long-term storage foods such as retort foods (high-temperature and high-pressure sterilized foods) and high-moisture foods that tend to grow mold. be done.

In particular, in recent years, the use of cans and bottles for packaging foods that can be stored for a long period of time has decreased from the viewpoint of transportation costs and disposal of containers. The shape of the material is the mainstream.

When the container is a can or bottle, there is no invasion of oxygen from the outside, and it is sufficient to remove only the remaining oxygen during packaging, so methods such as vacuum packaging and nitrogen gas replacement packaging have been used. When oxygen-absorbing packaging materials are used in place of cans and bottles, there is no problem of facility costs and production efficiency due to the use of special packaging means such as vacuum packaging and nitrogen gas replacement packaging as described above. However, since conventional oxygen-absorbing films are more permeable to oxygen than bottles and cans, it has been difficult to give retort pouch packaging materials the same shelf life as cans and bottles. Therefore, various oxygen-absorbing films and oxygen-absorbing packaging materials using such films have been developed that can also be suitably used as retort pouch packaging materials.

Oxygen-absorbing packaging materials currently in practical use include those in which iron or oxygen-deficient oxides are added to resins as oxygen-absorbing substances, and those in which unsaturated bonds are provided in part of the structure of a resin composition.

However, the use of iron-based oxygen-absorbing substances imposes restrictions on the use of metal detectors, and resin compositions having oxygen-deficient oxides or unsaturated bond structures are expensive as materials themselves.

On the other hand, organic substances such as ascorbic acids, reducing sugars such as glucose, polyhydric alcohols such as glycerin, phenols such as catechol, and phenolic carboxylic acids such as hydroxybenzoic acid are used as oxygen absorbing substances for oxygen scavengers. It is a substance that has been studied for a long time, and is inexpensive and safe.

For example, as an oxygen-absorbing packaging material using gallic acid (3,4,5-trihydroxybenzoic acid) among phenolcarboxylic acids as an oxygen-absorbing substance, Patent Document 1 discloses gallic acid and an alkaline substance in a thermoplastic resin. , discloses an oxygen-absorbing film formed from a resin composition to which an oxidation reaction catalyst is added. Further, Patent Document 2 discloses an oxygen-absorbing film in which a substrate, a gallic acid-containing layer, an alkaline substance-containing layer and a sealant layer are laminated in this order.

JP 2011-92921 A JP-A-10-138410

The inventors of the present invention have extensively studied an oxygen-absorbing film comprising an oxygen-absorbing layer containing an oxygen-absorbing substance such as gallic acid and containing an alkaline substance as an auxiliary agent. As a result, although the oxygen-absorbing film containing such an oxygen-absorbing layer and an alkaline substance is excellent in oxygen-absorbing performance, the laminate strength is not necessarily sufficient, and delamination occurs particularly between the substrate and the oxygen-absorbing layer. I found it easy.

Accordingly, an object of the present invention is to provide a laminate that maintains adhesion strength sufficient for practical use as a packaging material and is also excellent in oxygen absorption performance, and a package and a packaged article including the laminate.

A first aspect of the present invention provides a laminate comprising a first outermost layer, a water vapor barrier layer, an oxygen absorbing layer containing an oxygen absorbing substance, and a second outermost layer in this order.

In one embodiment, the first outermost layer comprises a base material having one main surface constituting one outermost surface of the laminate, and a water-soluble polymer interposed between the base material and the water vapor barrier layer. and a containment layer.

In another embodiment, the first outermost layer may further include an inorganic vapor deposited layer interposed between the base material and the water-soluble polymer-containing layer and formed of an inorganic vapor deposited layer.

In another embodiment, the water vapor barrier layer may contain a moisture permeation resistant resin.
In another embodiment, the water vapor barrier layer contains a moisture permeation resistant resin and a thermoplastic resin, and the blending ratio of the moisture permeation resistant resin is 50% by mass or more with respect to the total of the moisture permeation resistant resin and the thermoplastic resin. can be

In another embodiment, the water vapor barrier layer may include a moisture permeation resistant resin-containing layer and a thermoplastic resin containing layer interposed between the moisture permeation resistant resin containing layer and the first outermost layer.

In another embodiment, the ratio T ₁ :T ₂ between the film thickness T ₁ of the moisture permeation resistant resin-containing layer and the film thickness T ₂ of the thermoplastic resin-containing layer included in the water vapor barrier layer is 90:10 to 10:90. may be in the range of

In another embodiment, the moisture permeation resistant resin may have a moisture permeability coefficient (g·mm/m ² /day) of 0.5 or less.

In another embodiment, the moisture permeation resistant resin may be a cyclic olefin resin having a glass transition temperature of 80° C. or higher.

In another form, the laminate may further include an alkaline substance-containing layer between the oxygen absorbing layer and the second outermost layer.
In another form, the oxygen absorbing layer may further contain an alkaline substance.

In another embodiment, the laminate may contain the alkaline substance in a ratio of 40 to 100 parts by mass with respect to 100 parts by mass of the oxygen-absorbing substance.

In another embodiment, the laminate may contain the oxygen-absorbing substance in a proportion of 20% by mass to 60% by mass with respect to the total mass of the oxygen-absorbing layer.

In another form, the laminate may contain at least a phenol compound as the oxygen absorbing substance.

In another embodiment, the laminate may contain at least a phenol compound having a pyrogallol group as the oxygen-absorbing substance.

In another embodiment, the laminate may contain at least one selected from gallic acid and gallic acid esters as the oxygen-absorbing substance.

In another form, the second outermost layer may comprise a sealant layer.

A second aspect of the present invention provides a package including the laminate.
According to a third aspect of the present invention, there is provided a packaged article including the package and contents housed therein.

ADVANTAGE OF THE INVENTION According to this invention, the laminated body excellent in oxygen absorption performance, a package body containing the same, and a packaged article are provided, maintaining sufficient adhesive strength for practical use as a packaging material.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows schematically the laminated body which concerns on one Embodiment of this invention. Sectional drawing which shows roughly the laminated body which concerns on other embodiment of this invention. Sectional drawing which shows roughly the laminated body which concerns on other embodiment of this invention.

The laminate according to the present embodiment may be used in the form of a sheet as an oxygen-absorbing film, or may be used as a packaging material, for example, in the form of a bag. etc. is suitably used.

<Laminate>
A laminate according to this embodiment will be described below with reference to the drawings. Elements having the same or similar functions are denoted by the same reference numerals, and overlapping descriptions are omitted.

Typical configuration examples of the laminate according to this embodiment are shown in FIGS. 1 to 3. FIG.
FIG. 1 is a cross-sectional view schematically showing a laminate 1 according to the first embodiment. This laminate 1 includes a first outermost layer 10, a water vapor barrier layer 11-1, an oxygen absorbing layer 12a, an alkaline substance-containing layer 12b, and a second outermost layer 13. As shown in FIG. The first outermost layer 10 includes a substrate 10a, an inorganic deposited layer 10b made of an inorganic deposited layer, and a water-soluble polymer-containing layer 10c. The water vapor barrier layer 11-1 contains a moisture permeation resistant resin.

FIG. 2 is a cross-sectional view schematically showing the laminate 1 according to the second embodiment. This laminate 1 comprises a first outermost layer 10, a water vapor barrier layer 11-2, an oxygen absorbing layer 12a, an alkaline substance-containing layer 12b, and a second outermost layer 13. As shown in FIG. The first outermost layer 10 includes a substrate 10a, an inorganic deposited layer 10b made of an inorganic deposited layer, and a water-soluble polymer-containing layer 10c. The water vapor barrier layer 11-2 contains a moisture permeation resistant resin and a thermoplastic resin.

FIG. 3 is a cross-sectional view schematically showing the laminate 1 according to the third embodiment. This laminate 1 includes a first outermost layer 10, a water vapor barrier layer 11-3, an oxygen absorbing layer 12a, an alkaline substance-containing layer 12b, and a second outermost layer 13. As shown in FIG. The first outermost layer 10 includes a substrate 10a, an inorganic deposited layer 10b made of an inorganic deposited layer, and a water-soluble polymer-containing layer 10c. The water vapor barrier layer 11-3 includes a thermoplastic resin-containing layer 11a and a moisture permeation resistant resin-containing layer 11b.

In addition, in the laminate 1 shown in FIGS. 1 to 3, an adhesive layer (not shown) may be provided between any layers.

Materials and functions of each layer will be described below.
(First outermost layer)
The first outermost layer is a substrate having oxygen barrier properties. The first outermost layer may be a single-layer base material or a multi-layer base material, as long as it has oxygen barrier properties. In the laminate 1 according to the first to third embodiments shown in FIGS. , an inorganic deposited layer 10b made of an inorganic deposited layer, and a water-soluble polymer-containing layer 10c.

As the base material 10a, polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamide (nylon (registered trademark)), polyethylene naphthalate, etc., or a copolymer of these polymers is used. Materials that are usually used as packaging materials, such as coalescence, can be used. In addition, it is also possible to use a plastic substrate coated with a coating liquid such as polyvinyl alcohol, ethylene vinyl alcohol, and polyvinylidene chloride, which has a relatively high barrier property among resin films. The base material 10a is appropriately selected from the above materials according to the application, the layer structure of the first outermost layer, and the like.

The substrate 10a may contain known additives such as plasticizers, antioxidants, colorants, fillers, UV absorbers, antistatic agents, and antiblocking agents, if necessary.

The inorganic deposition layer 10b is made of, for example, oxides, nitrides, or fluorides of aluminum, titanium, zirconium, tin, magnesium, etc., or their composites, and is formed by a vacuum deposition method, a sputtering method, or a plasma chemical vapor deposition method. It is formed by a vacuum process such as a phase growth method (Chemical vapor deposition; CVD method). By including the inorganic deposition layer 10b in the first outermost layer 10, the oxygen barrier property can be further enhanced.

The water-soluble polymer-containing layer 10c may contain a water-soluble polymer and have swelling properties with water. The water-soluble polymer-containing layer 10c swollen with water can enter the gaps of the inorganic deposition layer 10b and prevent the layer from cracking. Therefore, by including the water-soluble polymer-containing layer 10c in the first outermost layer 10, the oxygen barrier property of the first outermost layer 10 can be further enhanced.

Examples of the water-soluble polymer contained in the water-soluble polymer-containing layer 10c include urethane resin, phenol resin, acrylic resin, polyester/alkyd resin, and amino resin.

The water-soluble polymer-containing layer 10c may contain at least one of metal alkoxide and its hydrolyzate, or tin chloride, in addition to the water-soluble polymer.

Examples of metal alkoxides include tetraethoxysilane [Si(OC ₂ H ₅ ) ₄ ], triisopropoxyaluminum [Al(Oi-C ₃ H ₇ ) ₃ ], and the like.
M (OR) _n
(M: metal such as Si, Ti, Ai, Zr, etc., R: alkyl group such as CH ₃ , C ₂ H ₅ ). Among them, tetraethoxysilane and triisopropoxyaluminum are preferable because they are relatively stable in an aqueous solvent after hydrolysis.

Tin chloride can be, for example, stannous chloride (SnCl ₂ ), stannic chloride (SnCl ₄ ), or mixtures thereof, and can be used either anhydrous or hydrated.

The water-soluble polymer-containing layer 10c is, for example, a solution in which a water-soluble polymer and tin chloride are dissolved in an aqueous solvent (water or water/alcohol mixture), or a metal alkoxide is directly or previously hydrolyzed in the solution. A solution in which the treated materials are mixed is coated on the inorganic deposition layer 10b on the base material 10a, and then dried by heating.

The film thickness of the first outermost layer 10 can be appropriately set. From the standpoint of good workability and handleability, the film thickness may be 10 μm or more and 50 μm or less.

Below, the 1st outermost layer 10 may be called a "base material layer" or a "base film." As the first outermost layer made of a substrate film comprising the substrate 10a, the inorganic deposition layer 10b, and the water-soluble polymer-containing layer 10c, for example, the product name "GL-AE" (manufactured by Toppan Printing Co., Ltd.), etc. A commercial item can be used.

(oxygen absorption layer)
The oxygen absorbing layer 12a contains at least an oxygen absorbing material and a binder.
The oxygen-absorbing substance contained in the oxygen-absorbing layer 12a may be, for example, a phenol compound, a reducing sugar such as glucose, or a polyhydric alcohol such as glycerin, and in one form, a phenol compound is preferable. Phenolic compounds include gallic acid, ascorbic acid, catechol, hydroxybenzoic acid and the like. Among them, a phenol compound having a pyrogallol group is particularly preferable in that it has a large number of hydroxyl groups used for oxygen absorption. Phenolic compounds having a pyrogallol group may be, for example, gallic acid (3,4,5-trihydroxybenzoic acid) and gallic acid esters (eg, propyl gallate, ethyl gallate, octyl gallate, etc.). In one form, the oxygen-absorbing layer 12a may contain, as an oxygen-absorbing substance, at least one selected from gallic acid and gallic acid esters (hereinafter also referred to as “gallic acids”). It may contain at least one of propyl. Since these are food additives and are relatively inexpensive, it is possible to provide packaging materials that are safe, inexpensive, and have excellent oxygen absorption performance.

The binder contained in the oxygen absorbing layer 12a is not particularly limited, and may be polyester resin, polyurethane resin, polyether resin, acrylic resin, epoxy resin, ethylene-vinyl acetate resin, vinyl chloride. resins, silicone resins, rubber resins, and the like. A binder having oxygen permeability and water vapor permeability is particularly preferable in that the oxygen-absorbing substance and oxygen readily react with each other. One of these binders may be used alone, or two or more of them may be used in combination. Moreover, a cross-linking agent and a dispersing agent may be contained as necessary.

The oxygen absorbing layer 12a may further contain an alkaline substance. In each of the laminates 1 according to the first to third embodiments shown in FIGS. 1 to 3, an alkaline substance-containing layer 12b, which will be described later, is placed between the oxygen absorbing layer 12a and the second outermost layer 13. However, as another embodiment, the layered body may contain an alkaline substance in the form of a mixture of the oxygen absorbing substance and the alkaline substance in the oxygen absorbing layer 12a without the alkaline substance containing layer 12b. .

In the laminate 1, the alkaline substance functions as an auxiliary agent that promotes oxygen absorption by the oxygen-absorbing substance. For example, gallic acids are known to exhibit an excellent oxygen absorption function by reacting with oxygen in an environment where an alkaline substance and water are present. The gallic acid reaction proceeds sufficiently at pH 8 or higher.

When the oxygen absorbing layer 12a contains an alkaline substance, the alkaline substance may be 40 parts by mass to 100 parts by mass with respect to 100 parts by mass of the oxygen absorbing material contained in the oxygen absorbing layer 12a. It may be 100 parts by mass.

Furthermore, the oxygen-absorbing layer 12a may contain optional additives such as plasticizers, antioxidants, colorants, fillers, and ultraviolet absorbers, if necessary.

The content of the oxygen-absorbing substance in the oxygen-absorbing layer 12a can be appropriately set from the viewpoint of oxygen-absorbing performance, and may be, for example, 20% by mass to 60% by mass with respect to the total mass of the oxygen-absorbing layer 12a. , 30% to 60% by weight.

The types of coater and printing machine used for coating the oxygen absorbing layer 12a and the coating method thereof are not particularly limited. Typical examples include gravure coaters such as direct gravure, reverse gravure, kiss reverse gravure, and offset gravure, reverse roll coaters, micro gravure coaters, chamber doctor combined coaters, air knife coaters, dip coaters, bar coaters, A comma coater, a die coater, etc. can be mentioned.

(Water vapor barrier layer)
The laminate 1 according to the first embodiment shown in FIG. 1 includes a water vapor barrier layer 11-1 between the water-soluble polymer-containing layer 10c and the oxygen absorbing layer 12a that constitute the first outermost layer 10. As shown in FIG.

As described above, the inventors of the present invention found that, in an oxygen-absorbing film provided with an oxygen-absorbing layer containing an oxygen-absorbing substance such as gallic acid, the adhesion strength between the substrate layer and the oxygen-absorbing layer is particularly insufficient. Found. As a result of further intensive research by the present inventors on the cause, it was found that an alkaline substance added as an auxiliary agent for promoting oxygen absorption by an oxygen-absorbing substance penetrates from the sealant side, especially after oxygen absorption by the oxygen-absorbing substance. It has been found that the alkaline aqueous solution is dissolved in water and reaches the interface between the base material layer and the oxygen absorbing layer, thereby reducing the adhesion strength. It was also found that the decrease in adhesion strength between the base layer and the oxygen-absorbing layer due to the alkaline aqueous solution is particularly large when the base layer includes the water-soluble polymer-containing layer 10c.

The laminate 1 according to the first embodiment shown in FIG. 1 includes a water vapor barrier layer 11-1 between the water-soluble polymer-containing layer 10c and the oxygen absorbing layer 12a. With this configuration, the water vapor barrier layer 11-1 blocks the alkaline aqueous solution generated by the water permeating through the second outermost layer 13 side. As a result, the first outermost layer 10 and the oxygen absorbing layer 12a are prevented from permeating the first outermost layer 10, which is a substrate layer, and the deterioration of the water-soluble polymer-containing layer 10c is suppressed. It is possible to maintain the adhesion strength between In addition, there is almost no deterioration of the water vapor barrier layer 11-1 due to moisture or an alkaline aqueous solution, or dimensional change due to water absorption. It is possible to prevent the occurrence of strength reduction between

The water vapor barrier layer 11-1 may be a layer substantially impermeable to moisture, and contains a moisture permeation resistant resin. The moisture permeation resistant resin may have a moisture permeability coefficient (g·mm/m ² /day) of 0.5 or less, or 0.1 or less. Here, moisture permeability coefficient (g·mm/m ² /day) = moisture permeability (g/m ² /day) x thickness (mm).

Among moisture-permeable resins, resins having excellent chemical resistance and less dimensional change due to water absorption are preferable, and examples thereof include cyclic olefin resins. Here, the cyclic olefin-based resin includes cyclic olefin copolymer (COC), which is a copolymer made from olefin such as norbornene and ethylene, and a polymer obtained by ring-opening polymerization and hydrogenation of norbornene. Included are certain cyclic olefin polymers (COPs).

COC has a moisture permeability coefficient (g·mm/m ² /day) of 0.03 or less, and COP has a moisture permeability coefficient of 0.001 or less. The moisture permeability coefficient of these cyclic olefin resins is lower than the moisture permeability coefficient of 0.6 to 0.9 for polyethylene, which is suitably used as a sealant, and the moisture permeability coefficient of 0.7 for unstretched polypropylene (Cast Polypropylene; CPP). It exhibits excellent resistance to moisture permeation, and is suitable for forming a water vapor barrier layer. Examples of COC include APEL manufactured by Mitsui Chemicals, Inc. and ZEONEX manufactured by Zeon Corporation.

In addition to cyclic olefin resins, vinylidene chloride (moisture permeability coefficient of 0.03 or less), polyester (moisture permeability coefficient of about 0.2), and biaxially oriented polypropylene (OPP) (moisture permeability coefficient of about 0.03). Since 1) has a low moisture permeability coefficient and corresponds to a moisture permeation resistant resin, it can be used for forming a water vapor barrier layer.

In one aspect of the present embodiment, the moisture permeation resistant resin is preferably a cyclic olefin resin having a glass transition temperature (Tg) of 80° C. or higher. Among them, cyclic olefin copolymers (COC) are preferred, and those having a Tg of 100° C. or higher are more preferred, those having a Tg of 120° C. or higher are even more preferred, and those having a Tg of 140° C. or higher are particularly preferred. A higher Tg provides a function unique to the cyclic olefin copolymer such as moisture permeability resistance during the manufacturing process of the laminate or the package containing the laminate, or even when the package is subjected to high-temperature sterilization such as boiling or retort. By maintaining a constant state, it is possible to completely prevent the alkaline aqueous solution from permeating the water vapor barrier layer 11-1 and the first outermost layer 10, which is the base material layer. Therefore, it is possible to prevent a decrease in adhesion strength between the first outermost layer 10 and the oxygen absorbing layer 12a.

The cyclic olefin component of the cyclic olefin copolymer used in the present invention is not particularly limited, and includes, for example, cyclopentene or its derivatives, cyclohexene or its derivatives, cycloheptene or its derivatives, cyclooctene or its derivatives, cyclononene or its derivatives, and the like. be able to. Then, a copolymer of one or more of these cyclic olefins and an α-olefin, preferably ethylene, propylene, 1-butene, 1-hexene or 4-methyl-1-pentene, is a cyclic olefin copolymer. can be used as

The water vapor barrier layer 11-1 can be formed by extruding a moisture-permeable resistant resin such as a cyclic olefin copolymer by a conventional method such as a T-die. The thickness of the water vapor barrier layer 11-1 may be, for example, 5 μm to 30 μm. From the viewpoint of manufacturing stability, it is preferable that the thickness is 5 μm or more. Alternatively, an existing film on the market may be purchased and used.

Between the first outermost layer 10 and the water vapor barrier layer 11-1, an anchor coat (AC) layer for adhering the first outermost layer 10 and the water vapor barrier layer 11-1 may be provided. good. The anchor coat layer is not particularly limited, and general anchor coat materials such as urethane and polyester can be used. Also, the moisture permeation resistant resin such as a cyclic olefin copolymer may be purchased in the form of a film and laminated between the first outermost layer 10 and the oxygen absorbing layer 12a with an adhesive interposed therebetween.

The laminate 1 according to the second embodiment shown in FIG. 2 is a modification of the vapor barrier layer 11-1 included in the laminate according to the first embodiment shown in FIG. In the laminate according to the second embodiment, the water vapor barrier layer 11-2 contains a moisture permeation resistant resin and a thermoplastic resin. A decrease in adhesion strength due to the alkaline aqueous solution reaching the interface between the base material and the oxygen absorbing layer over time can be suppressed by interposing a water vapor barrier layer containing a moisture permeation resistant resin. By blending, it is possible to improve adhesion by improving compatibility with the substrate. Moreover, blending a thermoplastic resin is preferable from the viewpoint of cost.

Thermoplastic resins have a moisture permeability coefficient (g·mm/m ² /day) higher than 0.5 and do not correspond to moisture permeation resistant resins, and their alkali resistance is not high. Therefore, the thermoplastic resin can be mixed within a range that does not hinder the desired function of the water vapor barrier layer 11-2. In one embodiment, the water vapor barrier layer 11-2 may contain a thermoplastic resin within a range where the blending ratio of the moisture permeation resistant resin to the total of the moisture permeation resistant resin and the thermoplastic resin satisfies 50% by mass or more. It may be contained within a range where the blending ratio of the moisture permeation resistant resin to the total of the wet resin and the thermoplastic resin satisfies 50% by mass to 90% by mass. If the blending ratio of the permeation-resistant resin is less than 50% by mass, the alkaline aqueous solution may enter the first layer 10 (substrate side) through the thermoplastic resin, or the thermoplastic resin itself of the water vapor barrier layer 11-2 may deteriorate. As a result, the adhesion strength between the first layer 10 and the oxygen absorbing layer 12a may decrease.

As the thermoplastic resin contained in the water vapor barrier layer 11-2, a resin having low moisture permeability (high resistance to moisture permeation) and high alkali resistance is preferable. For example, polyethylene such as high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polypropylene, amorphous polyester, etc. The heat of

The water vapor barrier layer 11-2 can be formed by the same method as the water vapor barrier layer 11-1, and can be formed by extrusion using an existing method such as a T-die. The thickness of the water vapor barrier layer 11-2 may be, for example, 5 μm to 30 μm. From the viewpoint of manufacturing stability, it is preferable that the thickness is 5 μm or more. Alternatively, an existing film on the market may be purchased and used.

An AC layer may be provided between the first outermost layer 10 and the water vapor barrier layer 11-2. Also, a water vapor barrier layer 11-2 may be laminated between the first outermost layer 10 and the oxygen absorbing layer 12a via an adhesive.

The laminate 1 according to the third embodiment shown in FIG. 3 is a modification of the vapor barrier layer 11-2 in the laminate 1 according to the second embodiment shown in FIG. In the laminate 1 according to the third embodiment, the water vapor barrier layer 11-3 contains a moisture permeation resistant resin and a thermoplastic resin, but has a multi-layer structure unlike the water vapor barrier layer 11-2. That is, the water vapor barrier layer 11-3 includes a moisture permeation resistant resin-containing layer 11b containing a moisture permeation resistant resin and a thermoplastic resin containing layer 11a containing a thermoplastic resin. It has a structure in which the thermoplastic resin-containing layer 11a is interposed between it and the resin-containing layer 11b.

The thermoplastic resin-containing layer 11a and the moisture permeation-resistant resin-containing layer 11b, which constitute the water vapor barrier layer 11-3, can be formed by the same method as the water vapor barrier layer 11-1. can be extruded at

In the water vapor barrier layer 5-3, the thermoplastic resin-containing layer 11a may have a thickness of, for example, 5 μm to 20 μm, and the moisture permeation-resistant resin-containing layer 11b may have a thickness of, for example, 5 μm to 30 μm. From the viewpoint of manufacturing stability, the thickness is preferably 5 μm or more. Even if the thickness of the moisture-permeable resin-containing layer exceeds 30 μm, the desired function does not change, so the thickness is excessive. Moreover, it is preferable to appropriately select the thickness of the moisture permeation resistant resin-containing layer depending on the amount of the alkaline substance contained in the oxygen-absorbing layer or the alkali-containing layer.

In one embodiment, the ratio T ₁ :T ₂ between the film thickness T ₁ of the moisture-permeable resin-containing layer 11b and the film thickness T ₂ of the thermoplastic resin-containing layer 11a in the water vapor barrier layer 5-3 is 90:10 to 10. :90, or 80:20 to 20:80.

An AC layer may be provided between the first outermost layer 10 and the water vapor barrier layer 11-3. Alternatively, the thermoplastic resin-containing layer 11a and the moisture permeation-resistant resin-containing layer 11b may be laminated between the first outermost layer 10 and the oxygen absorbing layer 12a with an adhesive interposed therebetween.

(Alkaline substance-containing layer)
The laminate 1 according to the first to third embodiments shown in FIGS. 1 to 3 includes an alkaline substance-containing layer 12b between the oxygen absorbing layer 12a and the second outermost layer 13. FIG. As described above, when the oxygen absorbing layer 12a contains an alkaline substance, the layered product 1 does not have to include the alkaline substance-containing layer 12b.

However, when the oxygen absorbing layer 12a contains a mixture of an oxygen absorbing substance and an alkaline substance, the oxygen absorbing performance is exhibited, but oxygen absorption by the oxygen absorbing substance begins during the preparation of the coating liquid. For this reason, compared to the case where the oxygen absorbing layer 12a and the alkaline substance-containing layer 12b exist as separate layers like the layered bodies 1 according to the first to third embodiments, the oxygen absorption rate after the layered body is produced is reduced. There is a problem that the performance is degraded. For this reason, it is preferable that the laminate has an oxygen-absorbing layer 12a and an alkaline-substance-containing layer 12b as separate layers, as shown in FIGS.

The alkaline substance-containing layer 12b contains at least an alkaline substance and a binder. The binder is not particularly limited, and any binder can be used as long as it exhibits adhesion to the oxygen absorbing layer 12a and the adhesive layer (not shown) or the second outermost layer 13. It may be the same or similar material as used for 12a or adhesive layer or second layer 13, or it may be a different material.

Alkaline substances contained in the alkaline substance-containing layer 12b include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, rubidium hydroxide, beryllium hydroxide, magnesium hydroxide, strontium hydroxide, barium hydroxide, Lithium carbonate, magnesium carbonate, potassium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, potassium sodium carbonate, sodium carbonate, potassium magnesium carbonate, potassium phosphate, potassium hydrogen phosphate, sodium citrate and the like. From the viewpoint of safety, it is preferably a food additive, and more preferably one having heat resistance to the extent that it can be kneaded into a thermoplastic resin.

In particular, sodium carbonate, potassium carbonate, calcium carbonate, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium hydroxide, tripotassium citrate, sodium citrate, calcium citrate, potassium hydrogen carbonate, which alone exhibits a pH of 8 or more, It is more preferable to use potassium pyrophosphate, calcined calcium, potassium phosphate, or sodium tartrate, since the amount of alkaline substances to be contained can be reduced and the cost can be lowered.

The addition amount of the alkaline substance contained in the alkaline substance-containing layer 12b may be 40 parts by mass to 100 parts by mass, preferably 50 parts by mass to 100 parts by mass, with respect to 100 parts by mass of the oxygen absorbing substance contained in the oxygen absorbing layer 12a. It may be parts by mass. If the amount of the alkaline substance added is less than 40 parts by mass, the pH is not necessarily sufficient to promote the oxygen absorption reaction in the oxygen-absorbing substance such as gallic acid, and the amount of oxygen absorption may decrease. On the other hand, even if the addition amount of the alkaline substance exceeds 100 parts by mass and the pH increases, the oxygen absorption amount cannot be expected to increase so much.

The alkaline substance-containing layer 12b may optionally contain additives known in the art such as adhesion promoters, plasticizers, antioxidants, colorants, fillers, UV absorbers, etc. good.

The thickness of the alkaline substance-containing layer 12b may be, for example, 0.1 μm or more and 20 μm or less. By having a film thickness within this range, good adhesion strength and strength of the coat layer itself can be obtained.

(Second outermost layer)
The laminate 1 according to the first to third embodiments shown in FIGS. 1 to 3 comprises a second outermost layer 13. FIG. The second outermost layer 13 is a layer that constitutes the surface of the laminate 1 opposite to the first outermost layer 10 as a substrate.

When the laminated body 1 is used as a packaging material and is used as a bag-like body or the like, the second outermost layer 13 preferably contains a sealant layer. The sealant layer imparts heat sealability to the laminate 1 . In this case, for example, the laminate 1 can be easily processed into a bag shape by stacking the second outermost layer 13, the sheet run, with the layer facing inward, and heat-sealing the peripheral edges and the like.

As the sealant layer, among thermoplastic resins, polyolefin resins are generally used. Specifically, low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE), linear low density polyethylene resin (LLDPE) ), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, ethylene-methacrylic acid resin copolymer, blended resin of polyethylene and polybutene, homopolypropylene resin (PP) , propylene-ethylene random copolymers, propylene-ethylene block copolymers, propylene-α-olefin copolymers, and other polypropylene resins.

(First embodiment)
In the first embodiment of the present invention, as shown in FIG. 1, a water vapor barrier is formed on a first outermost layer 10 comprising a substrate 10a, an inorganic deposited film 10b, and a water-soluble polymer-containing layer 10c in this order. It is a laminate formed by laminating a layer 11-1, an oxygen absorbing layer 12a, an alkaline substance-containing layer 12b, and a second outermost layer 13 in this order. By interposing a water vapor barrier layer 11-1 containing a moisture permeation resistant resin with a low water vapor permeability between the water-soluble polymer-containing layer 10c and the oxygen absorbing layer 12a, moisture permeating from the second outermost layer side The generated alkaline aqueous solution is blocked by the water vapor barrier layer 11-1. As a result, the aqueous alkaline solution permeates the water vapor barrier layer 11-1 and deteriorates the water vapor barrier layer 11-1 itself, or the aqueous alkaline solution reaches the interface with the water-soluble polymer-containing layer 10c on the substrate side, causing the water vapor barrier layer 11-1 to deteriorate. Since deterioration of the water-soluble polymer-containing layer is suppressed, it is possible to prevent a decrease in adhesion strength between the base material 10 and the oxygen absorbing layer 12a after absorbing oxygen while maintaining high oxygen adsorption performance. .

(Second embodiment)
The second embodiment of the present invention is as shown in FIG. 2. In contrast to the first embodiment, the water vapor barrier layer 11-2 has a structure in which a moisture permeation resistant resin and a thermoplastic resin are blended. there is In this configuration, by adding a thermoplastic resin to the water vapor barrier layer, it is possible to increase the adhesion strength between the base material consisting of the first outermost layer 10 and the water vapor barrier layer 11-2. It is possible to reduce costs by reducing the amount of cyclic olefin resin used.

(Third embodiment)
A third embodiment of the present invention is as shown in FIG. It has a two-layer structure. With this configuration, effects similar to those of the second embodiment can be obtained.

<Package>
A package according to the present embodiment includes the laminate described above. Specifically, at least a portion of the package is formed of the laminate described above. Note that the package according to the present embodiment may further have functional layers such as a print layer, a barrier layer, and a surface protective layer.

Application examples of the package of the present embodiment include, for example, bags, MA packaging materials, lid materials (top materials), sheets, bags with zippers, and cover films. In addition, the package of the bag-like body is formed by heating and bonding the peripheral edge portions of the two laminates described above so that the sealant layer as the second outermost layer 13 is on the inside. may Furthermore, a bag with a so-called "gusset" may be formed by interposing a third film in the peripheral portion where the lamination is performed.

The pouch package may have any shape, including rectangular, circular, and triangular. Alternatively, the zipper-equipped bag may be one in which a freely openable and closable fitting portion is provided at the opening of the package of the bag-like body by machining.

<Packaging goods>
A packaged product according to the present embodiment includes the above package and contents housed therein. Examples of the contents housed in the package include, but are not limited to, foods, beverages, cosmetics, pharmaceuticals, industrial materials, medical instruments, electronic devices, and cultural assets. In the packaged goods according to the present embodiment, when the content housed in the package is food, the food may be food with high water activity. Foods with high water activity include, for example, wheat flour, rice, beans, and fruit cakes with a water activity of 0.8 to 0.87, dried whitebait with a water activity of 0.87 to 0.91, salted salmon, sponge cake, etc. Examples include cheese, fruit juice, etc. with a water activity of 0.91 to 0.95, meat, ham, bacon, sausage, fresh fish, eggs, fruit, etc. with a water activity of 0.95 to 1.0.

EXAMPLES Specific examples of the present invention will now be described in detail with reference to the following examples, but the present invention is not limited to these.

<Example 1>
A laminate comprising a substrate layer, a water vapor barrier layer, an oxygen absorbing layer, an alkaline substance-containing layer and a sealant layer was produced by the following method.

First, as a substrate layer, a urethane-based anchor coating material is applied on a 12 μm-thick transparent vapor-deposited polyester film (polyester film/alumina vapor-deposited film/water-soluble polymer film) (GL-AE manufactured by Toppan Printing Co., Ltd.) by direct gravure method. A substrate layer obtained by coating was prepared.

A cyclic olefin copolymer (COC) (polyplastic TOPAS) having a Tg of 100° C. was extruded from a T-die to form a water vapor barrier layer (thickness: 10 μm) on the base material layer.

Next, a composition obtained by adding gallic acid as an oxygen-absorbing substance to a urethane-based binder was applied on the water vapor barrier layer by a direct gravure method to form an oxygen-absorbing layer having a thickness of 6 μm. The content of gallic acid with respect to the total mass of the oxygen absorbing layer was 30% by mass.

Furthermore, a composition obtained by adding an amount of sodium carbonate as an alkaline substance to a urethane-based binder in the same amount as gallic acid was coated on the oxygen-absorbing layer by a direct gravure method to form an alkaline substance-containing layer having a thickness of 6 μm. .

Next, a urethane-based adhesive having a thickness of 3 μm was applied to the alkaline substance-containing layer by a direct gravure method, and a polypropylene film (thickness: 30 μm) was attached as a sealant layer to the adhesive to obtain an oxygen-absorbing laminate 1. was made.

<Example 2>
Under the same conditions and procedures as in Example 1, except that a cyclic olefin copolymer (COC) having a Tg of 100° C. and polypropylene (PP) blended at a mass ratio of 1:1 was used as the water vapor barrier layer. An oxygen-absorbing laminate 2 was produced.

<Example 3>
As a water vapor barrier layer, polypropylene (PP) and a cyclic olefin copolymer (COC) having a Tg of 100°C were co-extruded onto the substrate layer at a mass ratio of 1:1 to form a PP film (film thickness of 5 µm) and COC. An oxygen-absorbing laminate 3 was produced under the same conditions and procedures as in Example 1, except that a two-layer structure of films (thickness of 5 μm) was formed.

<Example 4>
The conditions and conditions were the same as in Example 2, except that a cyclic olefin copolymer (COC) with a Tg of 60°C was used as the water vapor barrier layer instead of the cyclic olefin copolymer (COC) with a Tg of 100°C used in Example 2. An oxygen-absorbing laminate 4 was produced according to the procedure.

<Example 5>
As a water vapor barrier layer, polypropylene (PP) and a cyclic olefin copolymer (COC) having a Tg of 100°C were co-extruded onto the substrate layer at a mass ratio of 3:1 to form a PP film (thickness: 7.5 µm). and a COC film (thickness: 2.5 μm).

<Comparative Example 1>
A laminate comprising a substrate layer, an oxygen absorbing layer, an alkaline substance-containing layer and a sealant layer was produced by the following method.

First, a 12 μm-thick transparent vapor-deposited polyester film (GL-AE manufactured by Toppan Printing Co., Ltd.) was used as a base layer.

A composition obtained by adding gallic acid as an oxygen-absorbing substance to a urethane-based binder was applied onto the base material layer by a direct gravure method to form an oxygen-absorbing layer having a thickness of 6 μm. The content of gallic acid with respect to the total mass of the oxygen absorbing layer was 30% by mass.

Furthermore, a composition obtained by adding an amount of sodium carbonate as an alkaline substance to a urethane-based binder in the same amount as gallic acid was coated on the oxygen-absorbing layer by a direct gravure method to form an alkaline substance-containing layer having a thickness of 6 μm. .

Next, a urethane-based adhesive having a thickness of 3 μm was applied onto the alkaline substance-containing layer by a direct gravure method, and a polypropylene film (thickness: 30 μm) was laminated as a sealant layer thereon to obtain an oxygen-absorbing laminate 6. was made.

<Comparative Example 2>
Instead of a water vapor barrier layer (thickness 10 μm) formed using a cyclic olefin copolymer (COC) with a Tg of 100° C., polypropylene (PP) was extruded using a T-die to form a polypropylene layer (thickness 10 μm). An oxygen-absorbing laminate 7 was produced under the same conditions and procedures as in Example 1, except that the was formed.

<Evaluation method>
(Oxygen absorption performance)
For each of the laminates 1 to 7 produced above, a packaging bag having an overall size of 10 cm wide×10 cm long was produced, and 100 cc of air was injected into the bag. After being stored in a constant temperature bath at 50°C for a certain period of time, the oxygen concentration was measured, and from the difference from the initial oxygen concentration, each oxygen absorption amount was confirmed. When the residual oxygen content was 10% or less, it was evaluated as "A"; Table 1 shows the evaluation results of each laminate.

(adhesion strength)
Each of the laminates 1 to 7 prepared above was cut into a width of 15 mm and peeled at 90° C. at a speed of 300 mm/min using a tensile tester to evaluate the strength between the substrate and the oxygen absorbing layer. "A" when there is a practically sufficient adhesion strength of 3N or more, "B" when there is no practical problem in adhesion strength of 1N or more and less than 3N, and "B" when adhesion strength that causes practical problems of less than 1N is " C” was evaluated. Table 1 shows the evaluation results of each laminate.

As shown in Table 1, it can be seen that in Examples 1 to 3, a decrease in adhesion strength between the substrate and the oxygen absorbing layer after absorbing oxygen is suppressed while maintaining sufficient oxygen absorbing performance.

Further, from the comparison between Example 2 and Example 4, it can be seen that when the Tg of the water vapor barrier layer is low, the adhesion strength is slightly lowered, but even in Example 4, adhesion strength to the extent that there is no practical problem can be obtained. .

In addition, from the comparison between Example 3 and Example 5, when the ratio of the moisture permeation resistant resin is small, although the adhesion strength is slightly reduced, it is found that even in Example 5, adhesion strength to the extent that there is no practical problem can be obtained. Recognize.

On the other hand, in Comparative Examples 1 and 2, the adhesion strength between the base material and the oxygen-absorbing layer significantly decreased after oxygen absorption. This is probably because in Comparative Examples 1 and 2, the water permeating from the sealant side dissolves the alkali to form an alkaline aqueous solution, which migrates to the base material side and permeates, causing deterioration of the base material and the like.

From the above results, the laminate according to the embodiment of the present invention prevents a decrease in adhesion strength between the base material and the oxygen absorbing layer, and maintains sufficient adhesion strength for actual use as a packaging material or the like. It was found that the oxygen absorption performance was excellent.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the scope of the invention. Further, each embodiment may be implemented in combination as appropriate, in which case the combined effect can be obtained. Furthermore, various inventions are included in the above embodiments, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, if the problem can be solved and effects can be obtained, the configuration with the constituent elements deleted can be extracted as an invention.

1 Laminate 10 First outermost layer 10a Base material 10b Inorganic deposition layer 10c Water-soluble polymer-containing layer 11-1, 11-2, 11-3 Water vapor barrier layer 11a Thermoplastic resin-containing layer 11b Moisture-permeable resin-containing layer 12a oxygen absorbing layer 12b alkaline substance containing layer 13 second outermost layer

Claims (15)

A first outermost layer, a water vapor barrier layer, an oxygen absorbing layer containing an oxygen absorbing substance, an alkaline substance containing layer, and a second outermost layer are provided in this order, and the water vapor barrier layer is made of a moisture permeation resistant resin. and the moisture permeation resistant resin is a cyclic olefin resin having a glass transition temperature of 80° C. or higher. A first outermost layer, a water vapor barrier layer, an oxygen absorbing layer containing an oxygen absorbing substance, and a second outermost layer are provided in this order, the water vapor barrier layer containing a moisture permeation resistant resin, A laminate in which the moisture-permeable resin is a cyclic olefin resin having a glass transition temperature of 80° C. or higher, and the oxygen absorbing layer further contains an alkaline substance. The first outermost layer includes a base material having one main surface constituting one outermost surface of the laminate, and a water-soluble polymer-containing layer interposed between the base material and the water vapor barrier layer. 3. The laminate according to claim 1 or 2, comprising: 4. The laminate according to claim 3, wherein said first outermost layer is interposed between said base material and said water-soluble polymer-containing layer, and further comprises an inorganic deposited layer comprising a deposited layer of an inorganic substance. The water vapor barrier layer further contains a thermoplastic resin selected from polyethylene, polypropylene, and amorphous polyester. The laminate according to any one of claims 1 to 4, which is 50% by mass or more. The water vapor barrier layer includes a moisture permeation resistant resin-containing layer containing the moisture permeation resistant resin, and a thermoplastic resin containing layer interposed between the moisture permeation resistant resin containing layer and the first outermost layer. , The laminate according to any one of claims 1 to 4, wherein the thermoplastic resin is a resin selected from polyethylene, polypropylene and amorphous polyester . The ratio T _{1 :} T ₂ between the film thickness T 1 of the moisture-permeable resin-containing layer and the film thickness T ₂ of the thermoplastic resin-containing layer included in the water vapor barrier layer is in the range of 90:10 to 10:90. 7. The laminate of claim 6, wherein: When the oxygen absorbing layer further contains the alkaline substance, the oxygen absorbing layer contains the alkaline substance in a ratio of 40 parts by mass to 100 parts by mass with respect to 100 parts by mass of the oxygen absorbing substance. 8. The laminate according to any one of 7. 9. The laminate according to any one of claims 1 to 8, wherein the oxygen-absorbing substance is contained in a ratio of 20% by mass to 60% by mass with respect to the total mass of the oxygen-absorbing layer. 10. The laminate according to any one of claims 1 to 9, which contains at least a phenol compound as the oxygen-absorbing substance. The laminate according to any one of claims 1 to 10, which contains at least a phenol compound having a pyrogallol group as the oxygen-absorbing substance. 12. The laminate according to any one of claims 1 to 11, containing at least one selected from gallic acid and gallic acid ester as the oxygen absorbing substance. A laminate according to any preceding claim, wherein the second outermost layer comprises a sealant layer. A package comprising the laminate according to any one of claims 1 to 13. A packaged article comprising the package according to claim 14 and contents housed therein.

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