JP7531784B2 - Multilayer structure and container - Google Patents

Description

The present invention relates to a multilayer structure and a container.

Plastics are widely used for a variety of purposes because they are easy to mold and can be easily formed into various shapes. In particular, olefin resin bottles, whose inner walls are made of olefin resins such as low-density polyethylene, are ideal for use as containers for storing viscous slurry or paste-like contents such as ketchup, because the contents can be easily squeezed out.

In addition, bottles that contain viscous contents are often stored in an upside-down state in order to quickly drain the contents or to use up the contents completely without leaving any residue inside the bottle. For this reason, it is desirable for the bottle to have the property that when the bottle is upside-down, the viscous contents fall quickly without adhering to the inner wall of the bottle and remaining there.

For example, Patent Document 1 discloses a multilayer structure in the form of a container having, from the inside, a liquid layer, a plastic base layer, and a liquid diffusion prevention layer containing an ethylene-vinyl alcohol copolymer (EVOH), in that order. Since the liquid layer is provided on the inner surface of the multilayer structure, the liquid layer can improve the slipperiness of the contents. In addition, since the multilayer structure has a liquid diffusion prevention layer as an intermediate layer, it is possible to suppress the diffusion of the liquid constituting the liquid layer into the interior of the multilayer structure, and slipperiness can be maintained.

Patent No. 5673905

However, in the multilayer structure disclosed in Patent Document 1, at least a plastic base layer is present between the liquid layer and the liquid diffusion prevention layer, so the liquid in the liquid layer may diffuse into the plastic base layer, making it difficult to maintain sufficient slipperiness. In addition, there is a demand for further improvement in the liquid diffusion prevention performance of the liquid diffusion prevention layer.

The present invention aims to provide a multilayer structure in which high slipperiness due to the liquid layer is maintained for a long period of time, and a container made of the multilayer structure.

The multilayer structure according to the present invention comprises:
A liquid layer arranged as an outermost layer and composed of a liquid;
a liquid diffusion preventing layer provided adjacent to the liquid layer and including at least one of an ionomer and an acid copolymer;
Includes.

The multilayer structure according to the present invention comprises:
A liquid layer arranged as an outermost layer and composed of a liquid;
a liquid-containing layer that is provided adjacent to the liquid layer and contains the liquid and a resin;
a liquid diffusion preventing layer including at least one of an ionomer and an acid copolymer, the liquid diffusion preventing layer being provided adjacent to a surface of the liquid-containing layer opposite to a surface in contact with the liquid layer;
Includes.

The container according to the present invention is a container made of the multilayer structure according to the present invention, having the liquid layer as the innermost layer.

The present invention can provide a multilayer structure in which high slipperiness due to the liquid layer is maintained for a long period of time, and a container made of the multilayer structure.

1 is a cross-sectional view showing an example of a multilayer structure according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a multilayer structure according to a second embodiment of the present invention. 1 is a graph showing the amount of bleed-out liquid over time in Examples and Comparative Examples.

[Multilayer structure]
First Embodiment
The multilayer structure according to the first embodiment of the present invention includes a liquid layer and a liquid diffusion preventing layer. The liquid layer is disposed as the outermost layer (surface layer) of the multilayer structure and is composed of a liquid. The liquid diffusion preventing layer is disposed adjacent to the liquid layer and includes at least one of an ionomer and an acid copolymer.

In the multilayer structure according to this embodiment, a liquid diffusion prevention layer is provided adjacent to the liquid layer, so that the diffusion of the liquid constituting the liquid layer into the inside of the multilayer structure can be sufficiently suppressed. In addition, since the liquid diffusion prevention layer contains at least one of an ionomer and an acid copolymer, the electric charges (ions) possessed by the ionomer and the acid copolymer repel the liquid, and the migration of the liquid into the multilayer structure can be sufficiently suppressed. Therefore, in the multilayer structure according to this embodiment, the liquid layer can be retained on the surface of the multilayer structure for a long period of time, and high slipperiness can be maintained for a long period of time.

The multilayer structure according to this embodiment includes at least a liquid layer as the outermost layer (surface layer) and a liquid diffusion prevention layer provided adjacent to the liquid layer, and may further include other layers. Examples of the other layers include a polyolefin layer, an ethylene-vinyl alcohol copolymer layer, a polyethylene terephthalate layer, a metal layer, and the like. The multilayer structure may include one type of these layers, or may include two or more types. The thickness of the multilayer structure is not particularly limited, but may be, for example, 0.01 to 1.5 mm.

An example of the multilayer structure according to this embodiment is shown in FIG. 1. In the multilayer structure shown in FIG. 1, a liquid layer 1, a liquid diffusion prevention layer 2, and a polyolefin layer 3 are laminated in this order. The liquid layer 1 is provided as a liquid film on the surface of the liquid diffusion prevention layer 2. An adhesive may be used to bond the liquid diffusion prevention layer 2 and the polyolefin layer 3. In this multilayer structure, the liquid diffusion prevention layer 2, which prevents the liquid from penetrating the liquid layer 1, is provided in direct contact with the liquid layer 1, so that the migration of the liquid to the liquid diffusion prevention layer 2 and the polyolefin layer 3 can be sufficiently suppressed.

(Liquid Layer)
The multilayer structure according to the present embodiment includes a liquid layer as the outermost layer. The liquid constituting the liquid layer is not particularly limited as long as it can improve the slipperiness of the object, but from the viewpoint of preventing the liquid from volatilizing over time, a non-volatile liquid with a low vapor pressure under atmospheric pressure is preferable. For example, the boiling point of the liquid is preferably 200° C. or higher. In addition, the liquid may be an edible liquid. Examples of the liquid include fluorosurfactants, silicone oils, fatty acid triglycerides, vegetable oils, etc., and fatty acid triglycerides or vegetable oils are preferable. Examples of vegetable oils include soybean oil, rapeseed oil, olive oil, rice oil, corn oil, safflower oil, sesame oil, palm oil, castor oil, avocado oil, coconut oil, almond oil, walnut oil, hazel oil, salad oil, etc. These liquids may be used alone or in combination of two or more.

The liquid amount of the liquid layer is preferably 0.1 to 50.0 g/m ² , more preferably 0.7 to 30.0 g/m ² , and even more preferably 5.0 to 13.0 g/m ^2. When the liquid amount is 0.1 g/m ² or more, sufficient slippage is imparted. When the liquid amount is 50.0 g/m ² or less, the liquid can be sufficiently prevented from falling off from the multilayer structure surface. In addition, the change in the liquid amount over time can be reduced, and stable slippage can be achieved. The liquid layer only needs to cover at least a part of the surface of the liquid diffusion preventing layer, but it is preferable that the liquid layer covers the entire surface. As described later, the liquid layer can be formed, for example, by applying a liquid to the surface of the liquid diffusion preventing layer by spraying or the like.

(Liquid diffusion prevention layer)
The multilayer structure according to this embodiment includes a liquid diffusion preventing layer provided adjacent to the surface of the liquid layer opposite to the surface in contact with the outside air. The liquid diffusion preventing layer is a layer that suppresses the penetration of the liquid constituting the liquid layer and prevents the liquid from diffusing into the inside of the multilayer structure. The liquid diffusion preventing layer includes at least one of an ionomer and an acid copolymer. That is, the liquid diffusion preventing layer may include either an ionomer or an acid copolymer, or may include both. The ionomer and the acid copolymer have an electric charge (ion), so that they repel the liquid and can sufficiently suppress the migration of the liquid into the multilayer structure. The action of the electric charge works more effectively when the liquid is, in particular, oil.

The ionomer is a polymer having an ionic group on a side chain, terminal group, or main chain of a hydrophobic polymer main chain, and may be a metal salt. From the viewpoint of molding, the ionomer is preferably a metal salt of a copolymer of ethylene and an unsaturated carboxylic acid. Here, the copolymer is preferably a two-component copolymer of ethylene and one type of unsaturated carboxylic acid. As the unsaturated carboxylic acid, from the viewpoint of molding, acrylic acid or methacrylic acid is preferable. The content (acid content) of the unit derived from the unsaturated carboxylic acid in the copolymer is preferably 3 to 20 mass%. At least a part of the acid group (carboxyl group) of the copolymer is neutralized (ionized) by a metal ion. Examples of the metal ion include Na ⁺ , Li ⁺ , Mg ²⁺ , and Zn ²⁺ . The degree of neutralization (degree of ionization) by the metal ion is preferably 5 to 90 mol% of the acid group (carboxyl group).

The melt flow rate (MFR) of the ionomer at 190°C and a load of 2.16 kg is preferably 0.3 to 16.0 g/10 min, and more preferably 1.0 to 5.5 g/10 min. When the MFR is 0.3 g/10 min or more, blow molding and extrusion molding become possible. When the MFR is 16.0 g/10 min or less, the amount of ions contained in the ionomer increases, and migration of liquid into the multilayer structure can be further suppressed. The MFR is a value measured in accordance with JIS K7210:1999.

The acid copolymer may be a copolymer of an olefin and an unsaturated carboxylic acid, for example, a copolymer of ethylene and an unsaturated carboxylic acid. The copolymer is preferably a two-component copolymer of ethylene and one type of unsaturated carboxylic acid. From the viewpoint of molding processing, the unsaturated carboxylic acid is preferably acrylic acid or methacrylic acid. The content of units derived from the unsaturated carboxylic acid in the copolymer (acid content) is preferably 3 to 20% by mass.

The liquid diffusion prevention layer contains at least one of an ionomer and an acid copolymer, but may contain other components in addition to these. Examples of other components include polyolefins and ethylene-vinyl alcohol copolymers. However, from the viewpoint of fully exhibiting the liquid diffusion prevention performance of the ionomer and the acid copolymer, the ratio of the total mass of the ionomer and the acid copolymer to 100% by mass of the liquid diffusion prevention layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. In addition, the liquid diffusion prevention layer may be made of at least one of an ionomer and an acid copolymer.

The thickness of the liquid diffusion prevention layer is preferably 1.0 to 1500 μm, more preferably 1.0 to 800 μm, and even more preferably 2.0 to 50.0 μm. By having the thickness of 1.0 μm or more, migration of liquid into the multilayer structure can be sufficiently suppressed. Furthermore, in the case of a multilayer container, by having the thickness of 5.0 μm or less as part of the layer, costs can be particularly reduced.

(Polyolefin Layer)
The multilayer structure according to the present embodiment may further include a polyolefin layer from the viewpoint of usability such as cost, squeezability, and transportability. The multilayer structure may include one polyolefin layer, or may include two or more polyolefin layers. The polyolefin contained in the polyolefin layer is not particularly limited, and examples thereof include polyethylene such as low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), and linear very low density polyethylene (LVLDPE), polypropylene (PP), ethylene-propylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer, and ethylene-vinyl acetate copolymer. These may be used alone or in combination of two or more. The polyolefin layer may further include a lubricant, a modifier, a pigment, an ultraviolet absorber, and the like, as necessary. The thickness of the polyolefin layer is not particularly limited, and may be, for example, 300 to 1500 μm.

Second Embodiment
The multilayer structure according to the second embodiment of the present invention includes a liquid layer, a liquid-containing layer, and a liquid diffusion preventing layer. The liquid layer is disposed as the outermost layer (surface layer) of the multilayer structure and is composed of a liquid. The liquid-containing layer is provided adjacent to the liquid layer and includes the liquid and a resin. The liquid diffusion preventing layer is provided adjacent to the surface of the liquid-containing layer opposite to the surface in contact with the liquid layer and includes at least one of an ionomer and an acid copolymer.

In the multilayer structure according to this embodiment, a part of the liquid blended into the resin of the liquid-containing layer bleeds out (seeps out) onto the surface of the liquid-containing layer to form a liquid layer. Therefore, even if the amount of liquid in the liquid layer decreases over time, the liquid gradually bleeds out from the liquid-containing layer to supply the liquid to the liquid layer, and high slipperiness is maintained for a long period of time. In particular, in this embodiment, a liquid diffusion prevention layer is provided adjacent to the liquid-containing layer, so that the diffusion of the liquid contained in the liquid-containing layer into the multilayer structure is suppressed. This suppresses the reduction in the amount of liquid held in the liquid-containing layer over time, and promotes the bleeding out of the liquid onto the surface of the liquid-containing layer, so that high slipperiness is maintained for a long period of time. Furthermore, as in the first embodiment, since the liquid diffusion prevention layer contains at least one of an ionomer and an acid copolymer, the charges (ions) of the ionomer and the acid copolymer repel the liquid, and the migration of the liquid to the multilayer structure can be sufficiently suppressed, and high slipperiness can be maintained for a long period of time. In this embodiment, an adhesive (adhesive layer) may be interposed between the liquid-containing layer and the liquid-diffusion prevention layer to bond them together. In other words, "adjacent" may be adjacent via an adhesive (adhesive layer).

The multilayer structure according to this embodiment includes at least a liquid layer as the outermost layer (surface layer), a liquid-containing layer provided adjacent to the liquid layer, and a liquid diffusion prevention layer provided adjacent to the liquid-containing layer, and may further include other layers. Examples of the other layers include a polyolefin layer, an ethylene-vinyl alcohol copolymer layer, a polyethylene terephthalate layer, and a metal layer. The multilayer structure may include one of these layers, or may include two or more of them. The thickness of the multilayer structure is not particularly limited, but may be, for example, 250 to 1500 μm. The same layers as those in the first embodiment may be used as the liquid diffusion prevention layer and the polyolefin layer.

An example of the multilayer structure according to this embodiment is shown in FIG. 2. In the multilayer structure shown in FIG. 2, a liquid layer 1, a liquid-containing layer 4, a liquid diffusion prevention layer 2, and a polyolefin layer 3 are laminated in this order. The liquid layer 1 is formed as a liquid film on the surface of the liquid-containing layer 4 by bleeding out the liquid contained in the liquid-containing layer 4. An adhesive may be used to bond the liquid diffusion prevention layer 2 to the liquid-containing layer 4 and the polyolefin layer 3. In this multilayer structure, the liquid diffusion prevention layer 2 that prevents the penetration of the liquid is provided adjacent to the liquid-containing layer 4, so that the migration of the liquid contained in the liquid-containing layer 4 to the liquid diffusion prevention layer 2 and the polyolefin layer 3 is sufficiently suppressed, and the amount of the liquid that bleeds out can be increased.

(Liquid-containing layer)
The multilayer structure according to this embodiment includes a liquid-containing layer adjacent to the liquid diffusion prevention layer. The liquid-containing layer includes a liquid and a resin. The liquid contained in the liquid-containing layer bleeds out onto the surface, forming a liquid layer as a liquid film. The liquid may be the same as that in the first embodiment. The resin may be any resin that can be blended with the liquid and gradually bleed out the liquid over time, and may include, for example, polyolefin (polyethylene, polypropylene, cyclic olefin copolymer, etc.). These resins may be used alone or in combination of two or more. In addition to the liquid and resin, the liquid-containing layer may contain other components such as antioxidants, lubricants, and antistatic agents. The liquid-containing layer may be formed by blending the liquid, the resin, and any other components.

The content of the liquid contained in the liquid-containing layer is preferably 2.0 to 25.0% by mass, and more preferably 3.0 to 15.0% by mass, relative to 100% by mass of the liquid-containing layer. By having the content within the above range, a sufficient amount of liquid for forming a liquid layer can be bled out to the surface.

The liquid amount of the liquid layer (amount of liquid bleed-out) is preferably 0.1 to 5.0 g/ ^m2 , and more preferably 0.5 to 4.5 g/ ^m2 . When the liquid amount is 0.1 g/ ^m2 or more, sufficient slippage is imparted. When the liquid amount is 5.0 g/ ^m2 or less, the liquid can be sufficiently prevented from falling off from the surface of the multilayer structure. In addition, the change in the liquid amount over time can be reduced, and stable slippage can be achieved. The liquid layer only needs to cover at least a portion of the surface of the liquid-containing layer, but it is preferable that the liquid layer covers the entire surface.

The thickness of the liquid-containing layer is preferably 2.0 to 1500 μm, and more preferably 45.0 to 280 μm. A thickness of 2.0 μm or more allows a sufficient amount of liquid to be retained. Furthermore, a thickness of 280 μm or less allows a balance between ease of discharging the contents and cost.

[Method of manufacturing a multilayer structure]
The method for producing the multilayer structure according to the present invention is not particularly limited, and can be formed by forming a film that will be each layer other than the liquid layer by a method such as a casting method, a T-die method, a calendar method, or an inflation method, and then heat-pressing the film. It can also be formed by simultaneously extruding the materials that form each layer. In the first embodiment, the liquid layer can be formed by applying a liquid by spraying, immersion, coating, or the like. On the other hand, in the second embodiment, the liquid contained in the liquid-containing layer bleeds out to naturally form the liquid layer, so there is no need to apply a liquid separately.

[container]
The container according to the present invention is made of the multilayer structure according to the present invention and has a liquid layer as the innermost layer (the inner surface of the container). Since the container is made of the multilayer structure according to the present invention, the high slipperiness due to the liquid layer is maintained on the inner surface of the container for a long period of time, and even viscous contents do not adhere to and remain on the inner surface of the container, and can be quickly dropped and discharged.

The shape of the container is not particularly limited, and may be, for example, a cup, glass, bottle, bag (pouch), syringe, pot, tray, or other shape depending on the material. The container may also be stretch-molded.

The container made of the multilayer structure according to the first embodiment can be manufactured, for example, by forming the films that will be the layers other than the liquid layer by the method described above, heating and pressing them to form a preform, subjecting this to post-processing such as vacuum forming such as plug-assisted forming and blow forming to form a container, and applying liquid to the inner surface of the container by means of spraying, immersion, etc. Also, in a blow container, a liquid layer can be formed evenly over the entire surface of the liquid diffusion prevention layer (the inner surface of the container) by supplying liquid at the same time as blowing. Note that the amount of liquid that flows down can be minimized by filling the contents immediately after applying the liquid. On the other hand, in the manufacture of a container made of the multilayer structure according to the second embodiment, the liquid contained in the liquid-containing layer bleeds out and the liquid layer is naturally formed, so there is no need to apply liquid separately.

The container according to the present invention maintains high slipperiness on the inner surface for a long period of time, and is therefore suitable as a container filled with viscous contents such as ketchup, water-based glue, honey, various sauces, mayonnaise, mustard, dressing, jam, chocolate syrup, lotion and other cosmetic liquids, liquid detergent, shampoo, conditioner, etc. In this container, the contents can be quickly discharged without adhering to the inner wall of the container by tilting or turning the container upside down. For example, when the contents of the container are hydrophilic substances containing water such as ketchup, various sauces, honey, mayonnaise, mustard, jam, chocolate syrup, lotion, etc., the liquid constituting the liquid layer is preferably an oily liquid approved as a food additive, such as silicone oil, glycerin fatty acid ester, edible oil, etc.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The measurement of the MFR of the ionomer and the evaluation of the amount of liquid bleed-out over time were carried out by the following method.

[Measurement of MFR of ionomer]
The MFR of the ionomer at 190° C. under a load of 2.16 kg was measured in accordance with JIS K7210:1999.

[Evaluation of the amount of bleed-out liquid over time]
The multilayer structures produced in each of the Examples and Comparative Examples were stored under the condition of room temperature of 23° C., and the amount of bleed-out liquid on the surface of the multilayer structure was measured after a predetermined period of time had elapsed. The amount of bleed-out liquid was the weight of the evaporation residue of the cleaning liquid after washing with heptane.

[Example 1]
A multilayer structure having the following layer structure was manufactured by the following method. This multilayer structure is composed of (outside) polyolefin layer/adhesive layer A/liquid diffusion prevention layer/adhesive layer B/liquid-containing layer (inside). S131DG (trade name, manufactured by Sumitomo Chemical Co., Ltd., Random) was used for the polyolefin layer, modified olefin was used for the adhesive layer, and a mixture of PP and LLDPE containing 8% by mass of fatty acid triglyceride was used for the liquid-containing layer. The ionomer used contained Na ⁺ as the metal ion of the metal salt, and the MFR at 190 ° C. and a load of 2.16 kg was 1.3 g / 10 min. The thickness of the entire multilayer structure obtained was 560 μm, the thickness of the liquid-containing layer was 98 μm, the thickness of the adhesive layer B was 24 μm, the thickness of the liquid diffusion prevention layer was 42 μm, the thickness of the adhesive layer A was 19 μm, and the thickness of the polyolefin layer was 361 μm. The amount of liquid bleed-out over time was evaluated for the multilayer structure by the above method. The results are shown in Figure 3.

[Example 2]
Except for changing the thickness of the liquid diffusion preventing layer to 10 μm, a multilayer structure was produced and evaluated in the same manner as in Example 1. The results are shown in FIG.

[Example 3]
A multilayer structure was prepared and evaluated in the same manner as in Example 1, except that 1555 (trade name, manufactured by Dow Mitsui Polychemicals Co., Ltd., metal ion of metal salt: Na ⁺ , MFR at 190° C. and 2.16 kg load: 10 g/10 min) was used as the ionomer and the thickness of the liquid diffusion preventing layer was changed to 48 μm. The results are shown in FIG.

[Example 4]
A multilayer structure was prepared and evaluated in the same manner as in Example 1, except that 1557 (trade name, manufactured by Dow Mitsui Polychemicals Co., Ltd., metal ion of metal salt: Zn ²⁺ , MFR at 190° C. and 2.16 kg load: 5.5 g/10 min) was used as the ionomer and the thickness of the liquid diffusion preventing layer was changed to 44 μm. The results are shown in FIG.

[Comparative Example 1]
A multilayer structure was produced and evaluated in the same manner as in Example 1, except that EVOH (product name: EVAL L171B, manufactured by Kuraray Co., Ltd.) was used instead of the ionomer and the thickness of the liquid diffusion preventing layer was changed to 61 μm. The results are shown in FIG.

3, it was confirmed that the multilayer structures of Examples 1 to 4 had a large amount of liquid bleed-out over time, and it can be seen that the high slipperiness due to the liquid layer is maintained for a long period of time. On the other hand, in Comparative Example 1, in which EVOH was used as the material for the liquid diffusion preventing layer, the amount of liquid bleed-out over time was smaller than in Examples 1 to 4, in which an ionomer was used, and it can be seen that the slipperiness over time was lower than that of Examples 1 to 4.
The present invention includes the following embodiments.
[1] A liquid layer arranged as an outermost layer and composed of a liquid;
a liquid diffusion preventing layer provided adjacent to the liquid layer and including at least one of an ionomer and an acid copolymer;
A multi-layer structure comprising:
[2] A liquid layer arranged as an outermost layer and composed of a liquid;
a liquid-containing layer that is provided adjacent to the liquid layer and contains the liquid and a resin;
a liquid diffusion preventing layer including at least one of an ionomer and an acid copolymer, the liquid diffusion preventing layer being provided adjacent to a surface of the liquid-containing layer opposite to a surface in contact with the liquid layer;
A multi-layer structure comprising:
[3] The multilayer structure according to claim 1, wherein the liquid amount of the liquid layer is 0.1 to 50.0 g/m2 ^.
[4] The multilayer structure according to claim 2, wherein the liquid amount of the liquid layer is 0.1 to 5.0 g/m2 ^.
[5] The multilayer structure according to any one of claims 1 to 4, wherein the ionomer is a metal salt, and the metal ion of the metal salt is Na ⁺ , Li ⁺ , Mg ²⁺ or Zn ^{2+ .}
[6] The multilayer structure according to any one of claims 1 to 5, wherein the ionomer has a melt flow rate of 0.3 to 16.0 g/10 min at 190°C under a load of 2.16 kg.
[7] The multilayer structure according to any one of claims 1 to 6, wherein the liquid diffusion preventing layer has a thickness of 1.0 to 1,500 µm.
[8] The multilayer structure according to any one of claims 1 to 7, wherein the liquid is a fatty acid triglyceride or a vegetable oil.
[9] A container comprising the multilayer structure according to any one of claims 1 to 8, having the liquid layer as the innermost layer.

1 Liquid layer 2 Liquid diffusion prevention layer 3 Polyolefin layer 4 Liquid-containing layer

Claims (6)

A liquid layer arranged as an outermost layer and composed of a liquid;
a liquid-containing layer that is provided adjacent to the liquid layer and contains the liquid and a resin;
a liquid diffusion preventing layer including at least one of an ionomer and an acid copolymer, the liquid diffusion preventing layer being provided adjacent to a surface of the liquid-containing layer opposite to a surface in contact with the liquid layer;
A multi-layer structure comprising:
A multilayer structure, wherein the liquid diffusion preventing layer contains an ionomer, the ionomer being a metal salt, and the metal ion of the metal salt is Na ⁺ , Li ⁺ , Mg ²⁺ or Zn ²⁺ . 2. The multilayer structure according to claim 1 , wherein the liquid amount of the liquid layer is 0.1 to 5.0 g/ ^m2 . 3. The multilayer structure according to claim 1, wherein the ionomer has a melt flow rate of 0.3 to 16.0 g/10 min at 190° C. under a load of 2.16 kg. 4. The multilayer structure according to claim 1, wherein the liquid diffusion preventing layer has a thickness of 1.0 to 1500 μm. A multilayer structure according to any one of claims 1 to 4 , wherein the liquid is a fatty acid triglyceride or a vegetable oil. A container made of the multilayer structure according to any one of claims 1 to 5 , having the liquid layer as an innermost layer.