JP7419734B2 - Laminates, packages and packaged articles - Google Patents

Description

The present invention relates to a laminate, a package, and a packaged article.

In food packaging, the presence of oxygen inside the package may cause the contents, such as the food, to oxidize, resulting in deterioration or discoloration. In order to prevent oxidative deterioration of the packaged contents, it is effective to create an anoxic state by removing oxygen within the package and blocking external oxygen from entering the package.

However, since packaging is generally performed in the atmosphere, oxygen remains inside the package during packaging. To solve this problem, methods such as deaerating packaging, vacuum packaging, and gas displacement packaging are sometimes used as packaging methods to prevent oxygen from remaining inside the package.

However, using such special packaging means requires separate preparation of special filling and packaging equipment, resulting in disadvantages such as high equipment costs and lower production efficiency due to slower filling and packaging speeds. occurs. Furthermore, even if the packaging is done using the above-mentioned methods to prevent oxygen from remaining during packaging, it is difficult to maintain an oxygen-free condition inside the package because oxygen from the outside enters through the packaging material over time. .

Therefore, as a means to remove residual oxygen inside the package and oxygen that enters from the outside over time after packaging, an oxygen absorber consisting of a pouch filled with an oxygen-absorbing material is filled into the package containing the contents. method is used. In this method, oxygen can be removed by the oxygen absorbing material absorbing oxygen for a certain period of time, ie, a period during which the oxygen absorbing ability of the oxygen absorbing material 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, and is very effective in maintaining the inside of the package in an oxygen-free state. However, when an oxygen scavenger is used, it is time consuming and costly to fill the sachet with the oxygen absorbing material. Additionally, there are problems such as the possibility of consumers accidentally ingesting the product and the generation of waste.

As a means to eliminate these drawbacks and remove and block oxygen within the package for a certain period of time, we have developed an oxygen-absorbing film in which part of the film that makes up the packaging material has an oxygen-absorbing function, and oxygen-absorbing films that use it. Packaging materials have been devised and some have been put into practical use.

Oxygen-absorbing packaging materials such as those described above are currently often used in the food packaging field, and are particularly used for packaging long-term stored foods such as retort foods (high-temperature, high-pressure sterilized foods) and high-moisture foods that are prone to mold. It will be done.

In particular, in recent years, the use of cans and bottles for packaging long-term shelf-stable foods has decreased due to transportation costs and container disposal concerns, while retort pouch packaging, in which oxygen-absorbing film is provided as part of the packaging material, has decreased in recent years. The mainstream is in the form of wood.

When the container is a can or bottle, there is no intrusion of oxygen from the outside, and only the oxygen remaining during packaging needs to be removed, so methods such as vacuum packaging and nitrogen gas purge packaging have been used. When an oxygen-absorbing packaging material is used instead of a can or bottle, there are no problems with equipment costs or production efficiency caused by using special packaging means such as vacuum packaging or nitrogen gas displacement 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 expiration date as cans and bottles. Therefore, various oxygen-absorbing films and oxygen-absorbing packaging materials using the same have been developed, which can be suitably used as packaging materials for retort pouches.

Some of the 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 as part of the structure of the resin composition.

However, there are problems in that the use of iron-based oxygen absorbing materials limits the use of metal detectors, and that resin compositions with oxygen-deficient oxides and unsaturated bond structures are expensive.

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 in oxygen scavengers. It is a substance that has been studied for a long time and is inexpensive and safe.

It is known that gallic acid, a phenolic carboxylic acid, reacts with oxygen and oxidizes in a basic aqueous solution. Therefore, when using gallic acid as an oxygen-absorbing substance, water and a basic material are required, and the water can be contained in the packaging material by some means, or the water in the contents contained in the packaging can be used. It is also possible to do so.

It is conceivable that the basic material can be included in the packaging material to enable the oxidation reaction of gallic acid by dissolving it in the water and bringing it into contact with gallic acid.

For example, as an oxygen-absorbing packaging material using gallic acid (3,4,5-trihydroxybenzoic acid) as an oxygen-absorbing substance, Patent Document 1 describes gallic acid, an alkaline substance, and an oxidation reaction catalyst in a thermoplastic resin. An oxygen-absorbing film formed from a resin composition containing the following compounds is disclosed. Further, Patent Document 2 discloses an oxygen-absorbing film in which a base material, a gallic acid-containing layer, an alkali layer, and a sealant layer are laminated in this order.

JP2011-92921A Japanese Patent Application Publication No. 10-138410

The present inventors have conducted intensive research on an oxygen-absorbing film that is provided with an oxygen-absorbing layer containing an oxygen-absorbing substance such as gallic acid and contains an alkaline substance as an auxiliary agent. As a result, it was found that as the oxygen absorption layer progressed, the transparency of the film decreased due to whitening, making it difficult to visually recognize the contents.

It is thought that the decrease in transparency occurs due to the mechanism shown below. The water vapor that has entered the oxygen absorption layer hydrates with the alkaline substance that is the auxiliary agent, forming an aqueous solution of the alkaline substance or a water-containing substance in which a portion of the alkaline substance is swollen. If this aqueous solution or water-containing substance is compatible with the resin component used in the oxygen absorption layer, the film will not whiten because it will dissolve in the oxygen absorption layer. However, if this aqueous solution or water-containing substance is not compatible with the resin component used in the oxygen absorption layer, it will be in a state of being dispersed in the form of particles in the oxygen absorption layer. This dispersed state occurs throughout the oxygen absorbing layer as the amount of water absorbed into the film increases. As a result, visible light scattering occurs and the film becomes white.

Therefore, an object of the present invention is to provide a laminate having high oxygen absorption performance and excellent visibility of contents, as well as packages and packaging articles containing the same.

The present invention provides a laminate including at least an outermost layer, an oxygen absorbing layer , and an innermost layer, wherein the oxygen absorbing layer includes an oxygen absorbing substance-containing layer containing a phenol compound as an oxygen absorbing substance, and an alkali layer serving as an oxygen absorbing aid. It has a two-layer structure with an alkaline layer containing a substance, and the alkaline layer is a layer containing the alkaline substance in a matrix crosslinked with a resin and a hydrophilic compound different from the resin. It is.

Preferably, the above-mentioned hydrophilic compound is an organic compound. This organic compound is preferably a water-soluble compound containing at least one of an ether bond, a hydroxyl group, a carboxy group, or an amino group in the molecule.

The water-soluble compound containing an ether bond preferably contains two or more functional groups of the same type of polarity other than the ether bond in the molecule.

Preferably, the water-soluble compound containing an ether bond is polyethylene glycol or polypropylene glycol.

It is preferable that the resin contained in the resin composition of the oxygen absorbing layer contains at least one of a hydroxyl group, a carboxy group, and an amino group.

It is preferable that the oxygen absorbing substance contains at least a phenol compound having a pyrogallol group.

Further, it is preferable that the oxygen absorbing substance contains at least one of gallic acid and gallic acid ester.

The innermost layer may include a sealant layer, and the outermost layer may have oxygen and water vapor barrier properties.

Further, a package according to the present invention includes the above-mentioned laminate, and a package article according to the present invention includes a package including the above-mentioned laminate and contents accommodated therein. .

According to the present invention, there are provided a laminate having high oxygen absorption performance and excellent visibility of contents, as well as a package and a packaged article containing the same.

FIG. 1 is a cross-sectional view schematically showing a laminate according to an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing a laminate according to another embodiment of the present 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 in the form of a bag, for example, in foods, drugs, pharmaceuticals, cosmetics, electronic parts, etc. It is suitably used for etc.

<Laminated body>
The laminate according to this embodiment will be described below with reference to the drawings. Note that elements having the same or similar functions are given the same reference numerals, and redundant explanations will be omitted.

Typical configuration examples of the laminate according to this embodiment are shown in FIGS. 1 and 2.

FIG. 1 is a cross-sectional view schematically showing a laminate 1 according to an embodiment. This laminate 1 includes an outermost layer 10, an oxygen-absorbing substance-containing layer 11a, an alkali layer 11b, and an innermost layer 12 in this order. FIG. 2 is a cross-sectional view schematically showing a laminate according to another embodiment, and the laminate 1 shown in FIG. and an inner layer 12 in this order. In the laminate 1 shown in FIGS. 1 and 2, the oxygen-absorbing layer 11 is composed of the oxygen-absorbing substance-containing layer 11a and the alkaline layer 11b.

Note that in the laminate 1 shown in FIGS. 1 and 2, an adhesive layer (not shown) may be provided between any layers.

The materials, functions, etc. of each layer will be explained below.

(outermost layer)
The outermost layer is not particularly limited as long as it functions as a base material for forming the laminate of the present invention, but it is preferable that the outermost layer has excellent oxygen barrier properties in order to suppress oxygen from entering from the outermost layer.

The outermost layer 10 is made of 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. It is possible to use materials that are normally used as packaging materials, such as coalescence. The outermost layer 10 may have a multilayer structure including the above-mentioned materials, and if gas barrier properties such as oxygen and water vapor are required, a metal film containing aluminum as a main component or a vapor deposited film of metal oxide such as silica or aluminum may be used. A barrier film having a barrier layer formed on a base material may also be used.

The outermost layer 10 may contain known additives such as plasticizers, antioxidants, colorants, fillers, ultraviolet absorbers, antistatic agents, and antiblocking agents, if necessary.

The thickness of the outermost layer 10 can be set as appropriate, but a thickness of 10 μm or more and 100 μm or less can be suitably used. From the viewpoint of good processability and handleability, the film thickness is preferably 10 μm or more and 50 μm or less.

In the following, the outermost layer 10 may be referred to as a "base layer" or "base film."

(layer containing oxygen absorbing substance)
The oxygen-absorbing substance-containing layer 11a has at least an oxygen-absorbing substance and a resin composition as main components, and the resin composition contains at least a resin, a hydrophilic compound, and a curing agent.

The oxygen absorbing substance contained in the oxygen absorbing substance containing layer 11a 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. Examples of the phenolic compound include gallic acid, ascorbic acid, catechol, hydroxybenzoic acid, and the like. Among these, phenol compounds having a pyrogallol group are particularly preferred because they have a large number of hydroxyl groups used for oxygen absorption. The phenolic compound 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 substance-containing layer 11a 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 gallate. These are food additives and are relatively inexpensive, making it possible to provide packaging materials that are safe, inexpensive, and have excellent oxygen absorption performance.

The resin composition used for the oxygen-absorbing substance-containing layer 11a contains at least a resin, a hydrophilic compound, and a curing agent. The resin is not particularly limited as long as it functions as a matrix for fixing oxygen absorbing substances and alkaline substances, but resins are preferred from the viewpoint of versatility. Examples of resins include polyester resins, polyurethane resins, polyether resins, acrylic resins, polyvinyl acetal resins, epoxy resins, ethylene-vinyl acetate resins, vinyl chloride resins, silicone resins, rubber resins, etc. can be mentioned. In the present invention, the resin preferably contains a polar functional group such as a hydroxyl group, a carboxy group, or an amino group in order to enable crosslinking with a hydrophilic compound described below. These polar functional groups and a curing agent such as an isocyanate type or an epoxy type curing agent make it possible to form a matrix in which the resin and the hydrophilic compound described below are firmly bonded to each other. It is preferable that each resin has oxygen permeability and water vapor permeability, since the oxygen-absorbing substance and oxygen react more easily. One type of these resins may be used alone, or two or more types may be used in combination. It may also be used as a copolymer resin.

The hydrophilic compound contained in the oxygen-absorbing substance-containing layer 11a is not particularly limited as long as it can eliminate whitening of the film due to water-containing substances, such as water penetrating into the film or an aqueous solution of an alkaline substance that is an oxygen absorption aid. For example, fine particles having excellent water adsorption properties such as silica gel may be used. Particularly, fine particles made of a porous material having a nano-order pore size and a porosity of 85% or more, such as airgel, are suitable because they can obtain sufficient adsorption to water-containing substances by adding a small amount and have high transparency. Further, it is preferable to appropriately select and use a hydrophilic organic compound whose compatibility or dispersibility with the resin and various solvents contained in the oxygen-absorbing substance-containing layer 11a can be easily controlled. In particular, it is preferable to use a water-soluble compound containing a large amount of polar functional groups such as ether bonds, hydroxyl groups, carboxy groups, and amino groups that impart hydrophilicity. Although not limited in the present invention, specific examples of water-soluble hydrophilic compounds are shown below. As the compound containing an ether bond, ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, copolymers thereof, or partially modified compounds thereof may be used. Examples of compounds containing hydroxyl groups include polyhydric alcohols such as glycerin, pentaerythritol, sorbitol, and mannitol, polysaccharides such as carboxymethyl cellulose, guar gum, and xanthan gum, and polyvinyl alcohol. Examples of compounds containing a carboxy group include acrylic/methacrylic compounds or copolymers containing acrylic acid or methacrylic acid, and examples of compounds containing an amino group include ethylenediamine, polyethyleneamine, polyethyleneimine, and the like. Copolymers or modified products incorporating these hydrophilic compounds may be used, or resins with increased molecular weight may be used as the resin of the oxygen-absorbing substance-containing layer. On the other hand, resin particles or inorganic fine particles such as silica or alumina whose surfaces are chemically or physically coated with a hydrophilic compound may be used.

By using a resin composition containing these hydrophilic compounds, water-containing substances such as water, an aqueous solution or swollen product of an alkaline substance, and an oxidation reaction product of an oxygen-absorbing substance are uniformly distributed in the matrix of the oxygen-absorbing substance-containing layer. Since they can be compatible or dispersed, aggregation of water-containing substances can be suppressed, and whitening of the film can be suppressed. The mass ratio of the aforementioned resin/hydrophilic compound is preferably from 99/1 to 10/90, more preferably from 95/5 to 40/60. When the mass ratio of resin/hydrophilic compound is less than 99/1, it becomes difficult to suppress the decrease in transparency, and when it is more than 10/90, the water solubility of the resin composition containing the resin becomes significant, and as oxygen absorption progresses, There is a possibility that the oxygen-absorbing material-containing layer will dissolve and components of the oxygen-absorbing material-containing layer will flow out from the laminate.

The resin used for the above-mentioned hydrophilic compound and oxygen-absorbing substance-containing layer preferably has a structure in which the resin and the hydrophilic compound are integrated with a curing agent such as an isocyanate compound. The curing agent is not particularly limited as long as it can undergo a crosslinking reaction with the resin and the polar functional group of the hydrophilic compound, but from the viewpoint of versatility such as process suitability, a curing agent having an isocyanate as a reaction site is preferable. The content of the curing agent may be such that the hydrophilic compound is compatible with a water-containing substance such as water or an aqueous solution of an alkaline substance and does not flow through the oxygen-absorbing substance-containing layer. However, if the polar functional group that imparts hydrophilicity is a hydroxyl group, carboxy group, or amino group, these polar functional groups act as reaction sites with the curing agent, so the amount added must be such that hydrophilicity is not impaired. It is desirable to adjust to From this point of view, hydrophilic compounds preferably contain at least two polar functional groups in the molecule, and hydrophilic compounds containing ether bonds should contain two or more polar functional groups capable of crosslinking reactions. is preferred. Specific examples include polyethylene glycol, polypropylene glycol, and copolymers thereof. The reasons include that it is less toxic than monomers such as ethylene glycol and that there is less variation in content due to volatilization.

Furthermore, the oxygen-absorbing substance-containing layer 11a may contain arbitrary additives such as a plasticizer, an antioxidant, a colorant, a filler, and an ultraviolet absorber, as necessary.

The content of the oxygen-absorbing substance in the oxygen-absorbing substance-containing layer 11a can be set as appropriate from the viewpoint of oxygen-absorbing performance, and is, for example, 20% by mass to 70% by mass with respect to the total mass of the oxygen-absorbing substance-containing layer 11a. The content may be 30% by mass to 60% by mass.

There are no particular limitations on the types of coaters and printers used in coating the oxygen-absorbing material-containing layer 11a, and on their coating methods. Typical examples include gravure coaters such as direct gravure method, reverse gravure method, kiss reverse gravure method, offset gravure method, etc., reverse roll coater, micro gravure coater, coater with chamber doctor, air knife coater, dip coater, bar coater, Examples include comma coaters and die coaters.

(alkaline layer)
The laminate 1 according to the first embodiment shown in FIGS. 1 and 2 has an alkaline layer 11b between the oxygen-absorbing material-containing layer 11a and the innermost layer 12 or between the outermost layer 10a and the oxygen-absorbing material-containing layer 11a. Equipped with. As described later, when the oxygen-absorbing substance-containing layer 11a contains an alkaline substance, the laminate 1 does not need to include the alkaline layer 12b.

The alkaline layer 11b contains at least an alkaline substance and a resin composition, and the resin composition contains at least the above-described resin, hydrophilic compound, and curing agent. The resin composition of the alkaline layer 11b may be selected in consideration of the adhesion with the outermost layer 10, the oxygen-absorbing substance-containing layer 11a, the innermost layer 12, and an adhesive layer (not shown). The material may be the same or similar to that used for the containing layer 11a, the innermost layer 12, and the adhesive layer (not shown), or it may be a different material.

The alkaline substance contained in the alkaline layer 11b functions as an auxiliary agent that promotes oxygen absorption by the oxygen absorbing substance. For example, gallic acids are known to exhibit excellent oxygen absorption function by reacting with oxygen in an environment where an alkaline substance and water are present. The reaction of gallic acids proceeds satisfactorily at a pH of 8 or higher. Alkaline substances 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, Examples include lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium potassium carbonate, sodium carbonate, potassium magnesium carbonate, potassium phosphate, potassium hydrogen phosphate, and sodium citrate. From the viewpoint of safety, it is preferably a food additive, and further preferably has 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 have a pH of 8 or higher, It is more preferable to use potassium pyrophosphate, calcined calcium, potassium phosphate, or sodium tartrate because the amount of alkaline substances contained can be reduced and costs can be lowered.

The amount of the alkaline substance contained in the alkaline layer 11b may be 20 parts by mass to 100 parts by mass, and 50 parts by mass to 100 parts by mass, based on 100 parts by mass of the oxygen absorbing material contained in the oxygen absorbing material containing layer 11a. It may be parts by mass. If the amount of the alkaline substance added is less than 20 parts by mass, the pH is not necessarily sufficient to advance the oxygen absorption reaction in the oxygen absorbing substance such as gallic acid, and the amount of oxygen absorbed may decrease. On the other hand, even if the amount of the alkaline substance added exceeds 100 parts by mass and the pH increases, no increase in the amount of oxygen absorption can be expected.

The alkaline layer 11b may optionally contain any additives known in the art, such as adhesion promoters, plasticizers, antioxidants, colorants, fillers, ultraviolet absorbers, and the like.

In the example shown in FIGS. 1 and 2, the oxygen absorbing layer 11 has a two-layer structure of the oxygen absorbing substance containing layer 11a and the alkaline layer 11b, but the oxygen absorbing substance containing layer 11a may contain an alkaline substance. Accordingly, it is also possible to omit the alkaline layer 11b and configure the oxygen absorbing layer 11 with a single layer of the oxygen absorbing substance-containing layer 11a. In this case, the effect of the hydrophilic compound contained in the oxygen-absorbing substance-containing layer 11 becomes significant due to the presence of the alkaline substance.

When the oxygen-absorbing substance-containing layer 11a contains an alkaline substance, the alkaline substance may be 20 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 substance-containing layer 11a, It may be 50 parts by weight to 100 parts by weight.

However, when an oxygen absorbing substance and an alkaline substance are mixed in the oxygen absorbing substance-containing layer, oxygen absorbing performance is exhibited, but oxygen absorption by the oxygen absorbing substance starts at the stage of preparing the coating liquid. For this reason, compared to the case where the oxygen-absorbing material-containing layer 11a and the alkaline layer 11b exist as separate layers, as in the laminate 1 shown in FIGS. 1 and 2, the oxygen absorption performance after the laminate is manufactured is lower. There is a problem with the decline. For this reason, the laminate 1 preferably includes an oxygen-absorbing substance-containing layer 11a and an alkali layer 11b as separate layers, as shown in FIGS. 1 and 2.

(innermost layer)
The laminate 1 shown in FIGS. 1 and 2 includes an innermost layer 12. The innermost layer 12 is a layer that constitutes the surface of the laminate 1 opposite to the outermost layer 10 as a base material.

When the laminate 1 is used as a packaging material and is used in the form of a bag or the like, the innermost layer 12 preferably includes 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 laminate 1 with the innermost layer 12, which is the seatant layer, on the inside and heat-sealing the periphery.

Among thermoplastic resins, polyolefin resins are generally used as the sealant layer, and specifically, low density polyethylene resins (LDPE), medium density polyethylene resins (MDPE), linear low density polyethylene resins (LLDPE) are commonly used. ), ethylene-based resins such as ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, ethylene-methacrylic acid resin copolymer, blend resin of polyethylene and polybutene, and homopolypropylene resin (PP) , propylene-ethylene random copolymer, propylene-ethylene block copolymer, propylene-α-olefin copolymer, and other polypropylene resins can be used.

In the laminate 1 shown in FIGS. 1 and 2, oxygen and water vapor are supplied into the laminate from the innermost layer and diffuse into the oxygen-absorbing substance-containing layer 11a and the alkaline layer 11b. As a result, it becomes possible to absorb oxygen.

<Package>
The package according to this embodiment includes the above-mentioned laminate. Specifically, at least a portion of the package is formed of the above-mentioned laminate. Note that the package according to this embodiment may further be provided with functional layers such as a printing layer, a barrier layer, and a surface protection layer.

Application examples of the packaging body of this embodiment include, for example, bags, MA packaging materials, lid materials (top materials), sheets, bags with zippers, and cover films. Alternatively, the bag-like package may be formed by heating the peripheral edges of two of the above-mentioned laminates and bonding them together with the sealant layer as the innermost layer 12 on the inside. . Furthermore, a third film may be interposed at the peripheral portion where the materials are pasted together to form a so-called "gusseted" bag.

The bag-like package may have any shape including rectangular, circular, and triangular. Alternatively, the bag with a zipper may be one in which a fitting part that can be opened and closed is provided at the opening of the bag-like package by machining.

<Packaged goods>
The packaged article according to this embodiment includes the above-mentioned package and contents accommodated therein. Examples of the contents accommodated in the above package include, but are not particularly limited to, foods, beverages, cosmetics, pharmaceuticals, industrial materials, medical instruments, electronic devices, and cultural assets.

Hereinafter, specific examples of the present invention will be specifically described with reference to the following examples, but the present invention is not limited thereto.

<Example 1>
A laminate including a base material layer, an oxygen-absorbing substance-containing layer, an alkali layer, and a sealant layer was manufactured by the following method.

First, as the outermost layer, a film was used in which a barrier film having oxygen and water vapor barrier properties (product name: GL-AE, 12 μm thickness, manufactured by Toppan Printing Co., Ltd.) and a PET film (12 μm thickness) were laminated together with an adhesive.

Next, a coating was prepared by adding gallic acid, which is an oxygen absorbing substance, to a resin composition containing a polyvinyl acetal resin (20 wt% hydroxyl groups) and an isocyanate compound (trifunctional, NCO 12 wt%) in a mass ratio of 82/18. The liquid was applied onto the film using a wire bar to form a 10 μm thick layer containing an oxygen absorbing substance. The content of gallic acid with respect to the total mass of the oxygen-absorbing material-containing layer was 30% by mass.

Isocyanate-based A coating liquid prepared by adding sodium carbonate, which is an alkaline substance, to a resin composition containing 22 parts by weight of a compound (trifunctional, NCO 12 wt%) is applied onto the oxygen-absorbing substance-containing layer using a wire bar, An alkali layer with a thickness of 3 μm was formed. The content of sodium carbonate with respect to the total mass of the alkaline layer was 30% by mass.

Next, a urethane adhesive having a thickness of 3 μm was applied onto the alkali layer using a wire bar, and a polyethylene film (thickness: 30 μm) was bonded thereto as the innermost layer to prepare an oxygen-absorbing laminate.

<Example 2>
An oxygen-absorbing laminate was produced using a resin composition in which the water-soluble hydrophilic compound in Example 1 was changed to polypropylene glycol (molecular weight 700).
<Example 3>
An oxygen-absorbing laminate was produced in the same manner as in Example 2, except that the water-soluble hydrophilic compound in Example 2 was replaced with triol-type polypropylene glycol (molecular weight 1500).

<Comparative example 1>
In the alkaline layer in Example 1, an alkaline substance was added to a resin composition containing 11 parts by weight of an isocyanate compound (trifunctional, NCO 12 wt%) based on 100 parts by weight of polyvinyl acetal resin. A coating liquid prepared by adding a certain sodium carbonate was applied onto the oxygen-absorbing substance-containing layer using a wire bar to produce an oxygen-absorbing laminate in which an alkali layer with a thickness of 6 μm was formed. The content of sodium carbonate with respect to the total mass of the alkaline layer was 30% by mass.

<Evaluation method>
(Oxygen absorption performance)
Using the laminate produced above, a packaging bag having overall dimensions of 15 cm in width x 15 cm in length was produced in an environment of 25° C. and 20% Rh. The packaging bag contains a cloth moistened with 1.5 g of ion-exchanged water. Next, 400 cc of air was injected into the bag. After being stored for one week in a constant temperature bath at 40° C. and 20% Rh, the oxygen concentration was measured, and the amount of oxygen absorbed by each sample was confirmed from the difference from the initial oxygen concentration.
(Transparency of film)
In the above oxygen absorption performance evaluation, transparency was evaluated using a packaging bag that had been stored for one week in a constant temperature bath at 40° C. and 20% Rh. Transparency was determined by visually observing the appearance of the enclosed rag to determine the visibility of the contents, and then cutting the packaging bag into a 5 cm x 5 cm film piece and measuring the haze.

As shown in Table 1, Examples 1 to 3 exhibited sufficient oxygen absorption performance, low haze, and sufficient visibility.

From these results, the transparency of the laminate after oxygen absorption was improved by the oxygen absorption layer using a water-soluble hydrophilic compound in the resin composition.

Note that the present invention is not limited to the above-described embodiments, and can be variously modified at the implementation stage without departing from the gist thereof. Moreover, each embodiment may be implemented in combination as appropriate, and in that case, the combined effect can be obtained. Furthermore, the embodiments described above include various inventions, and various inventions can be extracted by combinations selected from the plurality of constituent features disclosed. For example, if a problem can be solved and an effect can be obtained even if some constituent features are deleted from all the constituent features shown in the embodiment, the configuration from which these constituent features are deleted can be extracted as an invention.

The present invention can be used as a packaging material for foods, drugs, pharmaceuticals, cosmetics, electronic parts, etc.

1 Laminated body 10 Outermost layer 11 Oxygen absorbing layer 11a Oxygen absorbing material containing layer 11b Alkaline layer 12 Innermost layer

Claims (12)

A laminate comprising at least an outermost layer, an oxygen absorbing layer , and an innermost layer in this order, wherein the oxygen absorbing layer includes an oxygen absorbing substance- containing layer containing a phenolic compound as an oxygen absorbing substance, and an alkali as an oxygen absorbing agent. It has a two-layer structure with an alkaline layer containing a substance, and the alkaline layer is a layer containing the alkaline substance in a matrix crosslinked with a resin and a hydrophilic compound different from the resin. laminate. The laminate according to claim 1, wherein the hydrophilic compound is an organic compound. 3. The laminate according to claim 2, wherein the organic compound is a water-soluble compound containing at least one of an ether bond, a hydroxyl group, a carboxy group, or an amino group in the molecule. 4. The laminate according to claim 3, wherein the water-soluble compound containing an ether bond contains two or more polar functional groups of the same type other than the ether bond in the molecule. 5. The laminate according to claim 4, wherein the water-soluble compound containing an ether bond is polyethylene glycol or polypropylene glycol. The laminate according to any one of claims 1 to 5, wherein the resin contained in the resin composition of the oxygen absorbing layer contains at least one of a hydroxyl group, a carboxylic acid, or an amino group. body. The laminate according to any one of claims 1 to 6, characterized in that the oxygen absorbing substance contains at least a phenol compound having a pyrogallol group. The laminate according to any one of claims 1 to 7, characterized in that the oxygen absorbing substance contains at least one of gallic acid and gallic acid ester. The laminate according to any one of claims 1 to 8 , wherein the innermost layer includes a sealant layer. The laminate according to any one of claims 1 to 9 , wherein the outermost layer has oxygen and water vapor barrier properties. A package comprising the laminate according to any one of claims 1 to 10 . A packaged article comprising a package including the laminate according to any one of claims 1 to 10, and contents accommodated in the package.

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