JP2024059746A - Laminate for packaging material and packaging material - Google Patents

Abstract

To provide a laminate for a packaging material capable of realizing a packaging material excellent in recyclability while having strength and barrier properties as a packaging material.SOLUTION: A laminate for a packaging material includes a base material and a heat seal layer. The heat seal layer includes a gas barrier resin layer and a polyolefin resin layer. The base material and the polyolefin resin layer are composed of the same polyolefin. The base material is a stretched resin film composed of a polyolefin. The thickness of the gas barrier resin layer is smaller than the thickness of the polyolefin resin layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laminate for packaging materials and a packaging material made from the laminate.

Conventionally, resin films made of resin materials have been used as a constituent material of packaging materials. For example, resin films made of polyolefins have moderate flexibility and transparency, as well as excellent heat sealability, and are therefore widely used as packaging materials.

Normally, resin films made of polyolefins cannot be used as substrates due to their inferior strength and heat resistance, and are instead laminated with resin films made of polyester, polyamide, etc. For this reason, typical packaging is made of laminated films in which the substrate and heat seal layer are made of different materials (for example, Patent Document 1).

In recent years, with the growing demand for a recycling-oriented society, there is a demand for packaging materials with high recyclability. However, as mentioned above, conventional packaging materials are made up of different resin materials, and because it is difficult to separate the individual resin materials, they are not currently recycled.

JP 2009-202519 A

The inventors discovered that by forming a polyolefin resin, which has conventionally been used as a heat seal layer, into a stretched resin film and using the base material by laminating it with a heat seal layer, it is possible to obtain a recyclable packaging material while maintaining its strength and heat resistance as a packaging material. In addition, the inventors discovered that by forming a heat seal layer by laminating a polyolefin resin layer and a barrier resin layer such as an ethylene-vinyl alcohol copolymer, it is possible to obtain a recyclable packaging material while imparting barrier performance.

The present invention has been made in view of the above findings, and an object of the present invention is to provide a laminate for packaging materials that can realize a packaging material that has excellent recyclability while also having the strength and barrier properties required for a packaging material.
Another object of the present invention is to provide a packaging material comprising the laminate for packaging materials.

The laminate for packaging material of the present invention comprises a substrate and a heat seal layer,
the heat seal layer comprises a gas barrier resin layer and a polyolefin resin layer;
The substrate and the polyolefin resin layer are made of the same polyolefin,
The substrate is a stretched resin film made of polyolefin,
The thickness of the gas barrier resin layer is smaller than the thickness of the polyolefin resin layer.

In one embodiment, the polyolefin content in the laminate for packaging materials is 80% by mass or more.

In one embodiment, the laminate for packaging materials of the present invention has an adhesive layer between the substrate and the heat seal layer.

In one embodiment, the laminate for packaging materials of the present invention has a vapor deposition film between the adhesive layer and the heat seal layer.

In one embodiment, the vapor-deposited film is an aluminum vapor-deposited film.
The adhesive layer contains a cured product of a resin composition that contains a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound.

In one embodiment, the heat seal layer includes an adhesive resin layer between the gas barrier resin layer and the polyolefin resin layer.

The packaging material of the present invention is characterized by being composed of the above laminate.

The present invention provides a laminate for packaging materials that has high recyclability.

The present invention also provides a laminate for packaging materials that has high strength, heat resistance, printability, oxygen barrier properties, and water vapor barrier properties.

Furthermore, the present invention can provide a packaging material made from the laminate for packaging materials.

1 is a schematic cross-sectional view showing one embodiment of a laminate for packaging material of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a laminate for packaging material of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a laminate for packaging materials of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a laminate for packaging materials of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a laminate for packaging materials of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a laminate for packaging material of the present invention. FIG. 1 is a perspective view showing one embodiment of a packaging material produced using the laminate for packaging materials of the present invention. FIG. 1 is a perspective view showing one embodiment of a packaging material produced using the laminate for packaging materials of the present invention.

(Laminate for packaging material)
As shown in FIG. 1, the laminate for packaging material 10 of the present invention comprises a substrate 11 and a heat seal layer 12 , and the heat seal layer 12 comprises a gas barrier resin layer 13 and a polyolefin resin layer 14 .

In one embodiment of the present invention, the packaging material laminate 10 may also include an adhesive layer 15 between the substrate 11 and the heat seal layer 12, as shown in FIG. 2.

In one embodiment of the present invention, the packaging material laminate 10 may further include a vapor deposition film 16 between the substrate 11 and the heat seal layer 12 as shown in FIG. 3, or between the adhesive layer 15 and the heat seal layer 12 as shown in FIG. 4.

In one embodiment of the present invention, the packaging material laminate 10 may also include an adhesive resin layer 17 between the gas barrier resin layer 13 and the polyolefin resin layer 14, as shown in FIG. 5.

In one embodiment of the present invention, as shown in FIG. 6, the polyolefin resin layer 14 of the packaging material laminate 10 may include a first polyolefin resin layer 18 and a second polyolefin resin layer 19.

Furthermore, in one embodiment of the present invention, the packaging material laminate 10 may have a gas barrier coating film between any of the layers (not shown).

The polyolefin content in the entire laminate for packaging materials of the present invention is preferably 80% by mass or more, and more preferably 90% by mass or more.
By making the polyolefin content in the entire laminate for packaging material of the present invention 80% by mass or more, the recyclability of the laminate for packaging material of the present invention can be improved.
The polyolefin content in the laminate for packaging materials means the ratio of the polyolefin content to the sum of the contents of the resin materials in each layer constituting the laminate.

The layers constituting the packaging laminate of the present invention are described below.

(Base material)
The substrate of the laminate for packaging material of the present invention is made of polyolefin, and the polyolefin used is the same as the polyolefin constituting the polyolefin resin layer described below. By using the same type of polyolefin for the substrate and the heat seal layer, the recyclability of the laminate for packaging material can be improved.

The base material is a stretched resin film made of polyolefin to maintain the strength and heat resistance required for packaging materials. The stretched resin film may be either a uniaxially stretched resin film or a biaxially stretched resin film.

The stretching ratio in the machine direction (MD) of the stretched resin film is preferably 2 times or more and 10 times or less, and more preferably 3 times or more and 7 times or less.
By making the stretching ratio of the stretched resin film in the longitudinal direction (MD) 2 times or more, the strength and heat resistance of the laminate for packaging material of the present invention can be improved. In addition, since the transparency of the substrate can be improved, when an image is formed on the adhesive layer side surface of the substrate, the visibility of the image can be improved. On the other hand, the upper limit of the stretching ratio in the longitudinal direction (MD) of the stretched resin film is not particularly limited, but it is preferably 10 times or less from the viewpoint of the breaking limit of the stretched film.

The stretching ratio in the transverse direction (TD) of the stretched resin film is preferably 2 to 10 times, and more preferably 3 to 7 times.
By making the stretching ratio of the stretched resin film in the transverse direction (TD) 2 times or more, the strength and heat resistance of the laminate for packaging material of the present invention can be improved. In addition, since the transparency of the substrate can be improved, when an image is formed on the adhesive layer side surface of the substrate, the visibility of the image can be improved. On the other hand, the upper limit of the stretching ratio in the transverse direction (TD) of the stretched resin film is not particularly limited, but it is preferably 10 times or less from the viewpoint of the breaking limit of the stretched film.

The polyolefin that can be used as the base material must be the same as the polyolefin resin that constitutes the heat seal layer, as described above. Examples of such polyolefins include polyethylene, polypropylene, polymethylpentene, ethylene-propylene copolymers, and propylene-butene copolymers, and among these, polyethylene and polypropylene are preferred.

Polyethylene includes high density polyethylene (HDPE) having a density greater than 0.945 g/ ^cm3 , medium density polyethylene (MDPE) having a density between 0.925 and 0.945 g/ ^cm3 , low density polyethylene (LDPE) having a density less than 0.925 g/ ^cm3 , and linear low density polyethylene (LLDPE).

In one embodiment, the substrate may have a structure including a layer containing high density polyethylene and a layer containing medium density polyethylene.
By providing a high-density polyethylene layer on the outer side of the substrate, the strength and heat resistance of the laminate for packaging materials of the present invention can be improved, and by providing a medium-density polyethylene layer, the stretchability of the resin film constituting the substrate can be improved.

For example, it has a structure consisting of a high density polyethylene layer/a medium density polyethylene layer from the outside.
By adopting such a constitution, it is possible to improve the stretchability of the film, and also to improve the strength and heat resistance of the laminate for packaging material of the present invention.
In this case, the thickness of the high density polyethylene layer is preferably thinner than the thickness of the medium density polyethylene layer.
The ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer is preferably 1/10 or more and 1/1 or less, and more preferably 1/5 or more and 1/2 or less.
By setting the ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer to be 1/10 or more, the strength and heat resistance of the laminate for packaging materials of the present invention can be improved. Also, by setting the ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer to be 1/1 or less, the stretchability of the film can be improved.

Also, for example, it may be configured from the outside in a layer of high density polyethylene/a layer of medium density polyethylene/a layer of high density polyethylene.
By adopting such a constitution, it is possible to improve the stretchability of the film, to improve the strength and heat resistance of the laminate for packaging material of the present invention, and to prevent the occurrence of curling in the substrate.
In this case, the thickness of the high density polyethylene layer is preferably thinner than the thickness of the medium density polyethylene layer.
The ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer is preferably 1/10 or more and 1/1 or less, and more preferably 1/5 or more and 1/2 or less.
By setting the ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer to be 1/10 or more, the strength and heat resistance of the laminate for packaging materials of the present invention can be improved. Also, by setting the ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer to be 1/1 or less, the stretchability of the film can be improved.

Also, for example, the laminate may be configured from the outside in a high-density polyethylene layer/medium-density polyethylene layer/low-density polyethylene layer or a linear low-density polyethylene layer/medium-density polyethylene layer/high-density polyethylene layer.
By adopting such a constitution, the stretchability of the film can be improved. In addition, the strength and heat resistance of the laminate for packaging material of the present invention can be improved. In addition, the occurrence of curling in the substrate can be prevented. Furthermore, the processability of the film can be improved.
In this case, the thickness of the high density polyethylene layer is preferably thinner than the thickness of the medium density polyethylene layer.
The ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer is preferably 1/10 or more and 1/1 or less, and more preferably 1/5 or more and 1/2 or less.
By setting the ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer to be 1/10 or more, the strength and heat resistance of the laminate for packaging materials of the present invention can be improved. Also, by setting the ratio of the thickness of the high density polyethylene layer to the thickness of the medium density polyethylene layer to be 1/1 or less, the stretchability of the film can be improved.
In addition, the thickness of the high density polyethylene layer is preferably thinner than the thickness of the low density polyethylene layer or the linear low density polyethylene layer.
The ratio of the thickness of the high density polyethylene layer to the thickness of the low density polyethylene layer or the linear low density polyethylene layer is preferably 1/10 or more and 1/1 or less, and more preferably 1/5 or more and 1/2 or less.
By making the ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer or the linear low-density polyethylene layer 1/10 or more, the heat resistance can be improved.
Furthermore, by setting the ratio of the thickness of the high density polyethylene layer to the thickness of the low density polyethylene layer or the linear low density polyethylene layer to 1/1 or less, the workability in stretching can be improved.

The polypropylene may be a homopolymer, a random copolymer or a block copolymer.
A polypropylene homopolymer is a polymer of only propylene, a polypropylene random copolymer is a random copolymer of propylene and an α-olefin other than propylene (e.g., ethylene, butene-1, 4-methyl-1-pentene, etc.), and a polypropylene block copolymer is a copolymer having a polymer block of propylene and a polymer block of the above-mentioned α-olefin other than propylene.
Among these polypropylenes, it is preferable to use a homopolymer or a random copolymer from the viewpoint of improving the transparency of the substrate and improving the visibility of an image formed on the adhesive layer side surface of the substrate. When the rigidity and heat resistance of the packaging material are important, a homopolymer can be used, and when impact resistance and the like are important, a random copolymer can be used.

In addition, as a raw material for obtaining polyolefin, an olefin monomer derived from biomass may be used instead of an olefin monomer derived from a fossil fuel. Since such an olefin monomer derived from biomass is a carbon-neutral material, it can be used as a packaging material with even less environmental impact.
Such biomass-derived polyolefins, such as polyethylene, can be produced by the method described in JP 2013-177531 A. Commercially available biomass-derived polyolefins (e.g., Green PE available from Braskem) may also be used.

Polyolefins recycled by mechanical recycling can also be used. Mechanical recycling generally refers to a method in which recovered polyolefin films are crushed and washed with an alkali to remove dirt and foreign matter from the film surface, and then dried at high temperature and reduced pressure for a certain period of time to diffuse and decontaminate contaminants remaining inside the film, removing dirt from the polyolefin film and returning it to polyolefin.

The substrate may have an image formed on its surface. The image may be formed on either side of the substrate, but it is preferable to form the image on the adhesive layer side, since this can prevent contact with the outside air and deterioration over time.
The image to be formed is not particularly limited, and may be a character, a pattern, a symbol, or a combination thereof.
The image can be formed using a conventionally known ink, but is preferably formed using an ink derived from biomass, which allows the laminate of the present invention to be used to produce a packaging material with less environmental impact.
The method for forming the image is not particularly limited, and examples of the method include conventionally known printing methods such as gravure printing, offset printing, flexographic printing, etc. Among these, flexographic printing is preferred because it can reduce the environmental load.

The substrate may have a vapor-deposited film on its surface, as described below.

In addition, the substrate is preferably subjected to a surface treatment, which can improve adhesion to adjacent layers.
The method of the surface treatment is not particularly limited, and examples thereof include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and/or nitrogen gas, and glow discharge treatment, as well as chemical treatments such as oxidation treatment using chemicals.
Furthermore, an anchor coat layer may be formed on the surface of the substrate using a conventionally known anchor coat agent.

The thickness of the substrate is preferably 5 μm or more and 300 μm or less, and more preferably 7 μm or more and 100 μm or less.
By making the thickness of the substrate 5 μm or more, the strength of the laminate for packaging material of the present invention can be improved, and by making the thickness of the substrate 300 μm or less, the processability of the laminate for packaging material of the present invention can be improved.

The substrate can be prepared by forming a polyolefin into a film by a T-die method, an inflation method or the like, and then stretching the film.
According to the inflation method, film formation and stretching can be carried out simultaneously.

When the substrate is produced by the T-die method, the MFR of the polyolefin is preferably 5 g/10 min or more and 20 g/10 min or less.
By making the MFR of the polyolefin 5 g/10 min or more, the processability of the laminate for packaging materials of the present invention can be improved, and by making the MFR of the polyolefin 20 g/10 min or less, the resin film can be prevented from breaking.

When the substrate is produced by an inflation method, the MFR of the polyolefin is preferably 0.5 g/10 min or more and 5 g/10 min or less.
By making the MFR of the polyolefin 0.5 g/10 min or more, the processability of the laminate for packaging materials of the present invention can be improved, and by making the MFR of the polyolefin 5 g/10 min or less, the film formability can be improved.

The substrate is not limited to those prepared by the above method, and commercially available substrates may also be used.

(Heat seal layer)
The laminate for packaging materials of the present invention comprises a heat seal layer comprising a gas barrier resin layer and a polyolefin resin layer.

In one embodiment, the heat seal layer may further include an adhesive resin layer between the gas barrier resin layer and the polyolefin resin layer.
By further providing an adhesive resin layer between the gas barrier resin layer and the polyolefin resin layer, the adhesion between these layers can be further improved.

In the present invention, the thickness of the gas barrier resin layer is smaller than the thickness of the polyolefin resin layer. By adopting such a configuration, the recyclability of the packaging material laminate of the present invention can be improved.
The thickness of the gas barrier resin layer is preferably at least 5 μm smaller than the thickness of the polyolefin resin layer, and more preferably at least 10 μm smaller. By making the thickness of the gas barrier resin layer at least 5 μm smaller than the thickness of the polyolefin resin layer, the recyclability of the packaging material laminate of the present invention can be further improved.

(Polyolefin resin layer)
The polyolefin resin layer constituting the heat seal layer is characterized by being composed of the same polyolefin as the polyolefin constituting the above-mentioned substrate. That is, the resin usable for the polyolefin resin layer is the polyolefin used for the above-mentioned substrate. By adopting such a constitution, it is possible to obtain a recyclable packaging material while maintaining the strength and heat resistance as a packaging material. However, the polyolefin resin layer is formed from an unstretched polyolefin resin film, or the polyolefin resin layer is formed by melt extrusion.

When polypropylene is used as the polyolefin resin layer, a heat seal modifier may be included to improve heat sealability. The heat seal modifier is not particularly limited as long as it has excellent compatibility with the polyolefin constituting the polyolefin resin layer, but examples thereof include olefin copolymers.

The thickness of the polyolefin resin layer is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.
By making the thickness of the polyolefin resin layer 5 μm or more, the heat sealability and recyclability of the polyolefin resin layer can be improved, and by making the thickness of the polyolefin resin layer 100 μm or less, the processability of the laminate for packaging material of the present invention can be improved.

In one embodiment, the polyolefin resin layer may have a multi-layer structure. In particular, when a heat seal modifier is added to polypropylene as the polyolefin resin layer, the modifier may migrate (leach out) to the gas barrier resin layer side, so the polyolefin resin layer may be configured as two or more layers, with the side to be heat sealed (the innermost layer side of the laminate) being a layer containing polyolefin resin and heat seal modifier, and the outer layer being a layer made of polypropylene resin. That is, an example of the multi-layer structure is a multi-layer structure consisting of a first polyolefin resin layer made of polyolefin and a second polyolefin resin layer made of polyolefin and heat seal modifier.

The content of the heat seal modifier in the second polyolefin resin layer is preferably 10% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 40% by mass or less.
By making the content of the heat seal modifier in the second polyolefin resin layer 10% by mass or more, the heat sealability of the second polyolefin resin layer can be improved. Also, by making the content of the heat seal modifier in the second polyolefin resin layer 50% by mass or less, the recyclability of the packaging material laminate of the present invention can be improved.

When the polyolefin resin layer has the above-mentioned two-layer structure, the thickness of the first polyolefin resin layer is preferably 5 μm or more and 50 μm or less, and more preferably 7 μm or more and 45 μm or less.
By making the thickness of the first polyolefin resin layer 5 μm or more, the recyclability of the packaging laminate of the present invention and the heat sealability of the first polyolefin resin layer can be improved, and by making the thickness of the first polyolefin resin layer 50 μm or less, the processability of the packaging laminate of the present invention can be improved.
The thickness of the second polyolefin resin layer is preferably 5 μm or more and 20 μm or less, and more preferably 7 μm or more and 15 μm or less.
By making the thickness of the second polyolefin resin layer 5 μm or more, the heat sealability of the second polyolefin resin layer can be improved, and by making the thickness of the second polyolefin resin layer 20 μm or less, the recyclability and processability of the laminate for packaging material of the present invention can be compatible.

(Gas Barrier Resin Layer)
The gas barrier resin layer constituting the heat seal layer contains at least one type of gas barrier resin, and examples thereof include ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyacrylonitrile, polyamides such as nylon 6, nylon 6,6 and polymetaxylyleneadipamide (MXD6), polyesters, polyurethanes, and (meth)acrylic resins. Among these, EVOH is preferred from the viewpoints of oxygen barrier properties and water vapor barrier properties.

The ethylene content in the EVOH is preferably from 20% by mass to 60% by mass, and more preferably from 27% by mass to 48% by mass.
By adjusting the ethylene content in the EVOH to 20% by mass or more, the processability of the laminate for packaging materials of the present invention can be improved. By adjusting the ethylene content in the EVOH to 60% by mass or less, the oxygen barrier property and water vapor barrier property of the laminate for packaging materials of the present invention can be improved.

The content of the gas barrier resin in the gas barrier resin layer is preferably 50% by mass or more, and more preferably 75% by mass or more.
By adjusting the content of the gas barrier resin in the gas barrier resin layer to 50% by mass or more, the oxygen barrier property and water vapor barrier property of the packaging material laminate of the present invention can be further improved.

The content of the gas barrier resin in the laminate for packaging material of the present invention is preferably 20% by mass or less, and more preferably 10% by mass or less.
By setting the content of the gas barrier resin in the laminate for packaging material to 20% by mass or less, the recyclability of the laminate for packaging material of the present invention can be improved.

The gas barrier resin layer may contain additives to the extent that they do not impair the properties of the present invention. Examples of additives include crosslinking agents, antioxidants, antiblocking agents, slip agents, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, compatibilizers, and pigments.

The thickness of the gas barrier resin layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less.
By making the thickness of the gas barrier resin layer 0.5 μm or more, the oxygen barrier property and water vapor barrier property of the packaging material laminate of the present invention can be improved, and by making the thickness of the gas barrier resin layer 10 μm or less, the recyclability of the packaging material laminate of the present invention can be improved.

(Adhesive Resin Layer)
In one embodiment, the heat seal layer may include an adhesive resin layer between the gas barrier resin layer and the polyolefin resin layer, which can improve the adhesion between the gas barrier resin layer and the polyolefin resin layer.

The adhesive resin layer contains at least one resin material, such as polyolefin, modified polyolefin, polyester, vinyl resin, and polyamide. Among these, polyolefin and modified polyolefin are preferred from the viewpoints of recyclability and adhesion.

The adhesive resin layer may contain the above additives as long as they do not impair the properties of the present invention.

The thickness of the adhesive resin is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less.
By making the thickness of the adhesive resin layer 0.5 μm or more, the adhesion between the gas barrier resin layer and the polyolefin resin layer can be improved, and by making the thickness of the adhesive resin layer 10 μm or less, the recyclability of the packaging material laminate of the present invention can be improved.

In a particularly preferred embodiment of the present invention, the heat seal layer of the laminate for packaging materials may include a gas barrier resin layer containing EVOH, an adhesive resin layer containing at least one of polyolefin and modified polyolefin, a first heat seal layer composed of polyolefin, and a second heat seal layer composed of polyolefin and a heat seal modifier. By adopting the above-mentioned configuration, the oxygen barrier property, water vapor barrier property, and heat seal property of the laminate for packaging materials of the present invention can be made extremely good. In addition, the adhesion between the layers constituting the heat seal layer can be made good.

The heat seal layer is an unstretched resin film that can be produced by co-extrusion of the material constituting the gas barrier resin layer and the material constituting the polyolefin resin layer (and the material constituting the adhesive resin layer, if provided) by a conventionally known method such as a T-die method or an inflation method.
The unstretched resin film thus produced can be laminated on a substrate via an adhesive layer, which will be described later.

(Vapor-deposited film)
The laminate for packaging material of the present invention may further include a vapor-deposited film between the substrate and the heat seal layer. By including a vapor-deposited film, the gas barrier properties, particularly the oxygen barrier properties and water vapor barrier properties, can be further improved.

Examples of vapor-deposited films include those composed of metals such as aluminum, and inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide.

The thickness of the evaporated film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and even more preferably 10 nm or more and 40 nm or less.
By making the thickness of the vapor-deposited film 1 nm or more, the oxygen barrier property and water vapor barrier property of the laminate for packaging material of the present invention can be further improved, and by making the thickness of the vapor-deposited film 150 nm or less, the occurrence of cracks in the vapor-deposited film can be prevented and the recyclability of the laminate for packaging material of the present invention can be improved.

For the vapor-deposited film to be an aluminum vapor-deposited film, the OD value is preferably 2 or more and 3.5 or less. This makes it possible to improve the oxygen barrier property and water vapor barrier property while maintaining the productivity of the laminate for packaging material of the present invention. In the present invention, the OD value can be measured in accordance with JIS-K-7361.

The vapor deposition film can be formed using a conventional method, for example, physical vapor deposition methods (PVD method) such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition methods (CVD method) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

Also, for example, a composite film consisting of two or more layers of vapor-deposited films of different inorganic oxides can be formed and used by combining both physical vapor deposition and chemical vapor deposition. The degree of vacuum in the vapor deposition chamber is preferably about 10 ^-2 to 10 ^-8 mbar before oxygen is introduced, and about 10 ^-1 to 10 ^-6 mbar after oxygen is introduced. The amount of oxygen introduced varies depending on the size of the vapor deposition machine. For the oxygen to be introduced, an inert gas such as argon gas, helium gas, or nitrogen gas may be used as a carrier gas to the extent that no problems occur. The film transport speed can be about 10 to 800 m/min.

It is preferable that the surface of the deposited film is subjected to the above-mentioned surface treatment. This can improve adhesion to adjacent layers.

(Adhesive Layer)
The laminate for packaging materials of the present invention may be provided with an adhesive layer for the purpose of improving adhesion between the surface on which the vapor deposition layer is provided and the surface to which the vapor deposition layer is to be adhered (adhering surface). That is, when a vapor deposition layer is provided on the surface of a substrate, an adhesive layer can be provided between the vapor deposition layer and the heat seal layer, and when a vapor deposition layer is provided on the surface of the gas barrier resin layer of the heat seal layer, an adhesive layer can be provided between the vapor deposition layer and the substrate.

The adhesive layer includes at least one adhesive, and may be a one-component curing type, a two-component curing type, or a non-curing type adhesive. The adhesive may be a solvent-free adhesive or a solvent-based adhesive, but from the viewpoint of environmental load, a solvent-free adhesive is preferably used.
Examples of solvent-free adhesives include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, and urethane adhesives. Among these, two-component curing urethane adhesives can be preferably used.
Examples of the solvent-based adhesive include rubber-based adhesives, vinyl-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and olefin-based adhesives.

In addition, in the laminate for packaging materials of the present invention, when the vapor-deposited film is an aluminum vapor-deposited film, it is preferable to use a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound as a two-component curing adhesive.
By configuring the adhesive layer in this way, the oxygen barrier property and water vapor barrier property of the laminate for packaging material of the present invention can be further improved. When a laminate with a vapor deposition film is applied to a packaging material, a bending load is applied to the laminate by a molding machine or the like, which may cause cracks in the aluminum vapor deposition film. By using the specific adhesive as described above, it is possible to suppress a decrease in the oxygen barrier property and water vapor barrier property even if cracks occur in the aluminum vapor deposition film.

Polyester polyols have two or more hydroxyl groups as functional groups in one molecule. Also, isocyanate compounds have two or more isocyanate groups as functional groups in one molecule. Polyester polyols have, for example, a polyester structure or a polyester polyurethane structure as the main skeleton.

Specific examples of resin compositions containing polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound include the PASLIM series sold by DIC Corporation.

The resin composition may further contain a plate-like inorganic compound, a coupling agent, cyclodextrin and/or its derivatives, etc.

As the polyester polyol having two or more hydroxyl groups in one molecule as a functional group, for example, the following [First Example] to [Third Example] can be used.
[Example 1] Polyester polyol obtained by polycondensing an ortho-oriented polycarboxylic acid or its anhydride with a polyhydric alcohol. [Example 2] Polyester polyol having a glycerol skeleton. [Example 3] Polyester polyol having an isocyanuric ring. Each polyester polyol will be described below.

The polyester polyol according to the first example is a polycondensate obtained by polycondensing a polycarboxylic acid component containing at least one or more types of orthophthalic acid and its anhydride, and a polyhydric alcohol component containing at least one type selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol.
In particular, polyester polyols in which the content of orthophthalic acid or its anhydride relative to the total amount of polyvalent carboxylic acids is 70 to 100% by mass are preferred.

The polyester polyol according to the first example essentially contains orthophthalic acid and its anhydride as the polycarboxylic acid component, but may be copolymerized with other polycarboxylic acid components as long as the effect of the present embodiment is not impaired.
Specifically, aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecane dicarboxylic acid, unsaturated bond-containing polycarboxylic acids such as maleic anhydride, maleic acid, and fumaric acid, alicyclic polycarboxylic acids such as 1,3-cyclopentane dicarboxylic acid and 1,4-cyclohexane dicarboxylic acid, aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyl dicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, anhydrides of these dicarboxylic acids, and ester-forming derivatives of these dicarboxylic acids, polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids, etc. are exemplified. Among these, succinic acid, 1,3-cyclopentane dicarboxylic acid, and isophthalic acid are preferred.
Two or more of the above other polyvalent carboxylic acids may be used.

As a polyester polyol according to the second example, a polyester polyol having a glycerol skeleton represented by the general formula (1) can be mentioned.
In general formula (1), R ₁ , R ₂ and R ₃ each independently represent H (hydrogen atom) or a group represented by the following general formula (2).

In formula (2), n represents an integer of 1 to 5, X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have a substituent, and Y represents an alkylene group having 2 to 6 carbon atoms.
However, at least one of R ₁ , R ₂ and R ₃ represents a group represented by formula (2).

In general formula (1), at least one of R ₁ , R ₂ and R ₃ must be a group represented by general formula (2). In particular, it is preferable that all of R ₁ , R ₂ and R ₃ are groups represented by general formula (2).

In addition, the compound may be a mixture _of two _{or more of a compound in which any one of R 1 ,} R ₂ , and R ₃ is a group represented by general formula (2), a compound in which any two of R 1, R ₂ , and R _{3 are groups represented by general formula (2), and a compound in which all of R 1, R 2, and R 3 are groups} represented by general formula (2).

X represents an optionally substituted arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group.
When X is substituted with a substituent, it may be substituted with one or more substituents, and the substituent is bonded to any carbon atom on X that is different from the free radical. The substituents include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, a N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.

In general formula (2), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, a propylene group, a butylene group, a neopentylene group, a 1,5-pentylene group, a 3-methyl-1,5-pentylene group, a 1,6-hexylene group, a methylpentylene group, or a dimethylbutylene group. Of these, a propylene group or an ethylene group is preferable, and an ethylene group is most preferable.

The polyester resin compound having a glycerol skeleton represented by general formula (1) can be synthesized by reacting glycerol, an aromatic polycarboxylic acid or its anhydride in which a carboxylic acid is substituted at the ortho position, and a polyhydric alcohol component as essential components.

Examples of aromatic polycarboxylic acids or anhydrides in which a carboxylic acid is substituted at the ortho position include orthophthalic acid or anhydride, naphthalene 2,3-dicarboxylic acid or anhydride, naphthalene 1,2-dicarboxylic acid or anhydride, anthraquinone 2,3-dicarboxylic acid or anhydride, and 2,3-anthracene carboxylic acid or anhydride.
These compounds may have a substituent at any carbon atom of the aromatic ring, such as a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, or a naphthyl group.

The polyhydric alcohol component may be an alkylene diol having 2 to 6 carbon atoms. Examples of such diols include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol.

The polyester polyol according to the third example is a polyester polyol having an isocyanuric ring represented by the following general formula (3).
In formula (3), R ₁ , R ₂ and R ₃ each independently represent "-(CH ₂ )n1-OH (wherein n1 represents an integer of 2 to 4)" or a structure represented by formula (4).

In general formula (4), n2 represents an integer of 2 to 4, n3 represents an integer of 1 to 5, X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have a substituent, and Y represents an alkylene group having 2 to 6 carbon atoms), with the proviso that at least one of R ₁ , R ₂ , and R ₃ is a group represented by general formula (4).

In the general formula (3), the alkylene group represented by -(CH ₂ )n1- may be linear or branched. Among these, n1 is preferably 2 or 3, and most preferably 2.

In formula (4), n2 represents an integer of 2 to 4, and n3 represents an integer of 1 to 5.
X represents an optionally substituted arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group.

When X is substituted with a substituent, it may be substituted with one or more substituents, and the substituent is bonded to any carbon atom on X that is different from the free radical. The substituents include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, a N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.
The substituent for X is preferably a hydroxyl group, a cyano group, a nitro group, an amino group, a phthalimido group, a carbamoyl group, an N-ethylcarbamoyl group, or a phenyl group, and most preferably a hydroxyl group, a phenoxy group, a cyano group, a nitro group, a phthalimido group, or a phenyl group.

In general formula (4), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, a propylene group, a butylene group, a neopentylene group, a 1,5-pentylene group, a 3-methyl-1,5-pentylene group, a 1,6-hexylene group, a methylpentylene group, or a dimethylbutylene group. Of these, a propylene group or an ethylene group is preferable, and an ethylene group is most preferable.

In formula (3), at least one of R ₁ , R ₂ and R ₃ is a group represented by formula (4). In particular, it is preferred that all of R ₁ , R ₂ and R ₃ are groups represented by formula (4).

In addition, the compound may be a mixture _of two _{or more of a compound in which any one of R 1 ,} R ₂ , and R ₃ is a group represented by general formula (4), a compound in which any two of R 1, R ₂ , and R _{3 are groups represented by general formula (4), and a compound in which all of R 1, R 2, and R 3 are groups} represented by general formula (4).

The polyester polyol having an isocyanuric ring represented by the general formula (3) can be synthesized by reacting a triol having an isocyanuric ring, an aromatic polycarboxylic acid or its anhydride in which a carboxylic acid is substituted at the ortho position, and a polyhydric alcohol component as essential components.

Examples of triols having an isocyanuric ring include alkylene oxide adducts of isocyanuric acid, such as 1,3,5-tris(2-hydroxyethyl)isocyanuric acid and 1,3,5-tris(2-hydroxypropyl)isocyanuric acid.

Examples of aromatic polycarboxylic acids or anhydrides in which the carboxylic acid is substituted at the ortho position include orthophthalic acid or anhydride, naphthalene 2,3-dicarboxylic acid or anhydride, naphthalene 1,2-dicarboxylic acid or anhydride, anthraquinone 2,3-dicarboxylic acid or anhydride, and 2,3-anthracene carboxylic acid or anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring.

Such substituents include chloro, bromo, methyl, ethyl, i-propyl, hydroxyl, methoxy, ethoxy, phenoxy, methylthio, phenylthio, cyano, nitro, amino, phthalimido, carboxyl, carbamoyl, N-ethylcarbamoyl, phenyl, and naphthyl groups.

The polyhydric alcohol component may be an alkylene diol having 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol.
Among these, polyester polyol compounds having an isocyanuric ring, which use 1,3,5-tris(2-hydroxyethyl)isocyanuric acid or 1,3,5-tris(2-hydroxypropyl)isocyanuric acid as the triol compound having an isocyanuric ring, orthophthalic anhydride as the aromatic polycarboxylic acid or its anhydride in which the carboxylic acid is substituted at the ortho position, and ethylene glycol as the polyhydric alcohol, are particularly excellent in oxygen barrier properties and adhesive properties and are therefore preferred.

Isocyanuric rings are highly polar and trifunctional, and can increase the polarity of the entire system and increase the crosslinking density. From this perspective, it is preferable for the adhesive resin to contain 5% by mass or more of isocyanuric rings relative to the total solid content.

The isocyanate compound has two or more isocyanate groups in the molecule.
The isocyanate compound may be either aromatic or aliphatic, and may be either a low molecular weight compound or a high molecular weight compound.
Furthermore, the isocyanate compound may be a blocked isocyanate compound obtained by subjecting a known isocyanate blocking agent to an addition reaction by a known, conventional appropriate method.
Among these, from the viewpoints of adhesiveness and retort resistance, polyisocyanate compounds having three or more isocyanate groups are preferred, and from the viewpoints of oxygen barrier property and water vapor barrier property, aromatic compounds are preferred.

Specific examples of the isocyanate compound include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, metaxylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds, as well as adducts, biurets, and allophanates obtained by reacting these isocyanate compounds with low-molecular-weight active hydrogen compounds or their alkylene oxide adducts, or high-molecular-weight active hydrogen compounds.
Examples of low molecular weight active hydrogen compounds include ethylene glycol, propylene glycol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, and metaxylylenediamine. Examples of molecular weight active hydrogen compounds include polymeric active hydrogen compounds such as various polyester resins, polyether polyols, and polyamides.

The phosphoric acid-modified compound is, for example, a compound represented by the following general formula (5) or (6).
In general formula (5), R ₁ , R ₂ and R ₃ are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, a phenyl group which may have a substituent, and an alkyl group having 1 to 4 carbon atoms which has a (meth)acryloyloxy group, at least one of which is a hydrogen atom, and n is an integer of 1 to 4.
In the formula, R ₄ and R ₅ are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, a phenyl group which may have a substituent, and an alkyl group having 1 to 4 carbon atoms and having a (meth)acryloyloxy group, n is an integer from 1 to 4, x is an integer from 0 to 30, and y is an integer from 0 to 30, except for the case where both x and y are 0.

More specifically, examples of such acids include phosphoric acid, pyrophosphoric acid, triphosphoric acid, methyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, dibutyl phosphate, 2-ethylhexyl acid phosphate, bis(2-ethylhexyl) phosphate, isododecyl acid phosphate, butoxyethyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, and polyoxyethylene alkyl ether phosphate, and one or more of these can be used.

The content of the phosphoric acid-modified compound in the resin composition is preferably from 0.005% by mass to 10% by mass, and more preferably from 0.01% by mass to 1% by mass.
By adjusting the content of the phosphoric acid-modified compound to 0.005% by mass or more, the oxygen barrier property and water vapor barrier property of the laminate for packaging materials of the present invention can be improved, and by adjusting the content of the phosphoric acid-modified compound to 10% by mass or less, the adhesiveness of the adhesive layer can be improved.

The resin composition containing the polyester polyol, the isocyanate compound and the phosphoric acid-modified compound may contain a plate-like inorganic compound, which can improve the adhesiveness of the adhesive layer and the bending load resistance of the laminate for packaging material of the present invention.
Examples of the plate-like inorganic compounds include kaolinite-serpentine group clay minerals (such as halloysite, kaolinite, endelite, dickite, nacrite, antigorite, and chrysotile) and pyrophyllite-talc group (such as pyrophyllite, talc, and keroli).

Examples of the coupling agent include a silane-based coupling agent, a titanium-based coupling agent, and an aluminum-based coupling agent, which are represented by the following general formula (7). These coupling agents may be used alone or in combination of two or more kinds.

Examples of silane coupling agents include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxytrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β(a Examples of such silanes include N-(aminoethyl) gamma-aminopropyl methyldimethoxysilane, N-β(aminoethyl) gamma-aminopropyl trimethoxysilane, N-β(aminoethyl) gamma-aminopropyl triethoxysilane, gamma-aminopropyl trimethoxysilane, gamma-aminopropyl triethoxysilane, N-phenyl-gamma-aminopropyl trimethoxysilane, gamma-chloropropyl trimethoxysilane, gamma-mercaptopropyl trimethoxysilane, 3-isocyanatopropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethyl-butylidene).

Examples of titanium-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraoctyl bis(didodecyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, bis(dioctyl pyrophosphate)ethylene titanate, isopropyl trioctyl nor titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, diisostearoyl ethylene titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, and dicumyl phenyl oxyacetate titanate.

Specific examples of aluminum-based coupling agents include acetoalkoxyaluminum diisopropylate, diisopropoxyaluminum ethyl acetoacetate, diisopropoxyaluminum monomethacrylate, isopropoxyaluminum alkyl acetoacetate mono(dioctyl phosphate), aluminum 2-ethylhexanoate oxide trimer, aluminum stearate oxide trimer, and alkyl acetoacetate aluminum oxide trimer.

The resin composition may contain cyclodextrin and/or a derivative thereof, which can improve the adhesiveness of the adhesive layer and the bending load resistance of the laminate for packaging material of the present invention.
Specifically, for example, cyclodextrin, alkylated cyclodextrin, acetylated cyclodextrin, hydroxyalkylated cyclodextrin, and other cyclodextrins in which the hydrogen atoms of the hydroxyl groups of the glucose units of cyclodextrin are substituted with other functional groups can be used. Branched cyclic dextrins can also be used.
Furthermore, the cyclodextrin skeleton in cyclodextrin and cyclodextrin derivatives may be any of α-cyclodextrin consisting of six glucose units, β-cyclodextrin consisting of seven glucose units, and γ-cyclodextrin consisting of eight glucose units.
These compounds may be used alone or in combination of two or more. Hereinafter, these cyclodextrins and/or their derivatives may be collectively referred to as dextrin compounds.

From the viewpoint of compatibility and dispersibility in the resin composition, it is preferable to use a cyclodextrin derivative as the cyclodextrin compound.

Examples of alkylated cyclodextrins include methyl-α-cyclodextrin, methyl-β-cyclodextrin, and methyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

Examples of acetylated cyclodextrins include monoacetyl-α-cyclodextrin, monoacetyl-β-cyclodextrin, and monoacetyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

Examples of hydroxyalkylated cyclodextrins include hydroxypropyl-α-cyclodextrin, hydroxypropyl-β-cyclodextrin, and hydroxypropyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

The thickness of the adhesive layer is preferably 0.5 μm or more and 6 μm or less, more preferably 0.8 μm or more and 5 μm or less, and even more preferably 1 μm or more and 4.5 μm or less.
By making the thickness of the adhesive layer 0.5 μm or more, the adhesiveness of the adhesive layer can be improved. In addition, when a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound is used, the bending load resistance of the laminate for packaging material can be improved.
By setting the thickness of the adhesive layer to 6 μm or less, the processability of the laminate for packaging materials can be improved.

The adhesive layer can be formed by applying and drying onto a substrate or the like using a conventional method such as direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine method, or transfer roll coating.

(Gas barrier coating film)
Within the scope not impairing the characteristics of the present invention, the laminate for a packaging material of the present invention may have, between any of the layers, a gas barrier coating film containing at least one type of resin composition such as a hydrolysate of a metal alkoxide or a hydrolysis condensate of a metal alkoxide obtained by polycondensing a mixture of a metal alkoxide and a water-soluble polymer by a sol-gel method in the presence of a sol-gel catalyst, water, an organic solvent, and the like.
This makes it possible to further improve the oxygen barrier property and water vapor barrier property of the laminate for packaging materials of the present invention.
Furthermore, when the vapor-deposited film is made of an inorganic oxide, the occurrence of cracks in the vapor-deposited film can be effectively prevented by providing a gas barrier coating film adjacent to the vapor-deposited film.

In one embodiment, the metal alkoxide is represented by the following general formula:
R ¹ _n M(OR ² ) m
(In the formula, R ¹ and R ² each represent an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the atomic valence of M.)

As the metal atom M, for example, silicon, zirconium, titanium, aluminum, etc. can be used.
Examples of the organic group represented by R ¹ and R ² include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and an i-butyl group.

Examples of metal alkoxides satisfying the above general formula include tetramethoxysilane (Si( _OCH3 ) _{4 )} , tetraethoxysilane (mass %) Si( _{OC2H5 ) 4} ), tetrapropoxysilane (Si( _OC3H7 ) ₄ ), and _{tetrabutoxysilane} (Si( _OC4H9 ) ₄ ).

It is also preferable to use a silane coupling agent together with the metal alkoxide.
As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used, and in particular, an organoalkoxysilane having an epoxy group is preferred. Examples of organoalkoxysilane having an epoxy group include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

Two or more of the above silane coupling agents may be used, and it is preferable to use the silane coupling agent in an amount within the range of about 1 to 20 parts by mass per 100 parts by mass of the total amount of the alkoxide.

As water-soluble polymers, polyvinyl alcohol and ethylene-vinyl alcohol copolymers are preferred, and from the viewpoints of oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance, it is preferable to use these in combination.

The content of the water-soluble polymer in the gas barrier coating film is preferably 5 parts by mass or more and 500 parts by mass or less per 100 parts by mass of the metal alkoxide.
By setting the content of the water-soluble polymer in the gas barrier coating film to 5 parts by mass or more per 100 parts by mass of the metal alkoxide, the oxygen barrier property and water vapor barrier property of the laminate for packaging materials of the present invention can be further improved. Also, by setting the content of the water-soluble polymer in the gas barrier coating film to 500 parts by mass or less per 100 parts by mass of the metal alkoxide, the film formability of the gas barrier coating film can be improved.

The thickness of the gas barrier coating film is preferably from 0.01 μm to 100 μm, and more preferably from 0.1 μm to 50 μm.
By making the thickness of the gas barrier coating film 0.01 μm or more, the oxygen barrier property and water vapor barrier property of the laminate for packaging material of the present invention can be improved. Furthermore, when the gas barrier coating film is provided adjacent to a vapor deposition film composed of an inorganic oxide, the occurrence of cracks in the vapor deposition film can be prevented.
Furthermore, by making the thickness of the gas barrier coating film 100 μm or less, the recyclability and processability of the laminate for packaging material of the present invention can be improved.

The gas barrier coating film can be formed by applying a composition containing the above-mentioned materials onto a substrate by a conventionally known means such as roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brushing, bar coding, or an applicator, and then polycondensing the composition by a sol-gel method.
The sol-gel catalyst is preferably an acid or an amine compound. As the amine compound, a tertiary amine that is substantially insoluble in water and soluble in an organic solvent is preferable, and examples thereof include N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. Among these, N,N-dimethylbenzylamine is preferable.
The sol-gel catalyst is preferably used in the range of 0.01 to 1.0 part by mass, and more preferably 0.03 to 0.3 part by mass, per 100 parts by mass of the metal alkoxide.
By using the sol-gel catalyst in an amount of 0.01 part by mass or more per 100 parts by mass of the metal alkoxide, the catalytic effect can be improved.
Furthermore, by setting the amount of the sol-gel catalyst to 1.0 part by mass or less per 100 parts by mass of the metal alkoxide, the thickness of the formed gas barrier coating film can be made uniform.

The composition may further contain an acid, which is used as a catalyst in the sol-gel process, mainly for the hydrolysis of alkoxides, silane coupling agents, etc.
The acid used may be a mineral acid such as sulfuric acid, hydrochloric acid, or nitric acid, or an organic acid such as acetic acid or tartaric acid.
The amount of the acid used is preferably 0.001 mole or more and 0.05 mole or less based on the total molar amount of the alkoxide and the alkoxide portion (eg, silicate portion) of the silane coupling agent.
By using an amount of the acid that is 0.001 mole or more based on the total mole amount of the alkoxide and the alkoxide portion (eg, silicate portion) of the silane coupling agent, the catalytic effect can be improved.
Furthermore, by making the amount of the alkoxide not more than 0.05 moles relative to the total molar amount of the alkoxide and the alkoxide portion (eg, silicate portion) of the silane coupling agent, the thickness of the formed gas barrier coating film can be made uniform.

The composition preferably contains water in an amount of 0.1 to 100 moles, more preferably 0.8 to 2 moles, per mole of the total amount of alkoxides.
By adjusting the water content to 0.1 mole or more per mole of the total molar amount of the alkoxides, the oxygen barrier property and water vapor barrier property of the laminate for packaging materials of the present invention can be improved.
Furthermore, by adjusting the content of water to 100 moles or more per mole of the total molar amount of the alkoxides, the hydrolysis reaction can be carried out quickly.

The composition may also contain an organic solvent. Examples of the organic solvent that can be used include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butanol.

Hereinafter, one embodiment of the method for forming a gas barrier coating film will be described.
First, a composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and optionally a silane coupling agent, etc. In the composition, a polycondensation reaction gradually proceeds.
Next, the composition is applied onto a substrate by the above-mentioned conventionally known method, and then dried.
This drying causes the polycondensation reaction between the alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains one) to proceed further, forming a composite polymer layer.
Finally, the composition is heated at a temperature of 20 to 250° C., preferably 50 to 220° C., for 1 second to 10 minutes to form a gas barrier coating film.

(Packaging materials)
The packaging material of the present invention is characterized in that it is composed of the above-mentioned laminate for packaging materials.
The shape of the packaging material is not particularly limited, and may be a bag shape as shown in FIG.

In one embodiment, a bag-shaped packaging material can be produced by folding the laminate of the present invention in half, overlapping the laminate so that the heat-sealable laminate is on the inside, and heat-sealing the ends.
In another embodiment, the bag-shaped packaging material can also be produced by overlapping two laminates so that the heat-sealable laminates face each other, and heat-sealing the ends thereof.
In the figure, the shaded areas indicate the heat-sealed areas.

The heat sealing method is not particularly limited, and can be performed by known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, ultrasonic sealing, etc.

In one embodiment, the packaging material has a stand-up pouch shape with a body and a bottom, as shown in FIG. 8.

A packaging material in the form of a stand-up pouch can be produced by heat-sealing the above laminate into a cylindrical shape with the heat-sealable laminate on the inside, forming a body, and then folding another laminate into a V shape with the heat-sealable laminate on the inside, sandwiching it in from one end of the body, and heat-sealing it to form a bottom.

The contents filled in the packaging material are not particularly limited, and may be liquid, powder, or gel. In addition, the contents may be food or non-food.
After filling the container with the contents, the opening can be heat sealed to form a package.

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

Example 1
an ethylene-vinyl alcohol copolymer (EVOH, manufactured by Kuraray Co., Ltd., product name: EVAL E171B, density: 1.14 g/cm ³ , melting point: 165° C., MFR: 1.7 g/10 min, ethylene content: 44% by mass) constituting a gas barrier resin layer;
A polyolefin (manufactured by Mitsui Chemicals, Inc., product name: Admer QF551, density: 0.89 g/cm ³ , melting point: 135° C., MFR: 2.5 g/10 min) constituting an adhesive resin layer;
A polypropylene (manufactured by TPC Corporation, product name: FL7540L, density: 0.90 g/cm ³ , melting point: 138° C., MFR: 7.0 g/10 min) constituting the first polyolefin resin layer;
a mixture of polypropylene (manufactured by TPC Corporation, product name: FL7540L, density: 0.90 g/cm ³ , melting point: 138° C., MFR: 7.0 g/10 min) and a heat seal modifier (manufactured by Mitsui Chemicals, Inc., product name: Tafmer A-4085S, density: 0.885 g/cm ³ , melting point: 66° C., MFR: 3.6 g/10 min) (polypropylene:heat seal modifier=60:40 (by mass)), which constitutes the second polyolefin resin layer;
The above was co-extruded by a T-die method to produce a heat seal layer having a structure of a gas barrier resin layer (2 μm)/adhesive resin layer (3 μm)/first polyolefin resin layer (15 μm)/second polyolefin resin layer (10 μm).

A 30 nm thick aluminum vapor deposition film was formed by PVD on the gas barrier resin layer of the heat seal layer prepared as described above. The vapor deposition concentration (OD value) of the vapor deposition film was measured and found to be 3.0.

As a substrate, a biaxially oriented polypropylene film having a thickness of 25 μm (manufactured by Toyobo Co., Ltd., product name: P2108) was prepared.
An image was formed on one surface of the biaxially stretched polypropylene film by gravure printing using a solvent-based gravure ink (Finart, manufactured by DIC Graphics Corporation).
The aluminum vapor deposition film-formed surface of the heat seal layer and the image-formed surface of the biaxially stretched polypropylene film were laminated via a two-component curing polyurethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-3600/H-689) to obtain a laminate for packaging materials of the present invention. The proportion of the same polyolefin (PP) in the laminate thus obtained was 84% by mass.

Example 2
Except for changing the thickness of the aluminum vapor-deposited film to 20 nm and changing the OD value of the vapor-deposited film to 2.0, a laminate for packaging material of the present invention was produced in the same manner as in Example 1. The proportion of the same polyolefin (PP) in the laminate thus obtained was 84 mass%.

Example 3
A laminate for packaging material of the present invention was produced in the same manner as in Example 1, except that the two-component curing polyurethane adhesive was changed to a two-component curing adhesive containing polyester polyol, an isocyanate compound and a phosphoric acid-modified compound (manufactured by DIC Corporation, product name: PASLIM VM001/VM102CP). The proportion of the same polyolefin (PP) in the laminate thus obtained was 84% by mass.

Comparative Example 1
A laminate for packaging materials was obtained in the same manner as in Example 1, except that a 25 μm-thick unstretched polypropylene film (manufactured by Toyobo Co., Ltd., product name: P1108) was used as the substrate. The proportion of the same polyolefin (PP) in the thus obtained laminate was 84 mass%.

Comparative Example 2
A polypropylene (manufactured by TPC Corporation, product name: FL7540L, density: 0.90 g/cm ³ , melting point: 138° C., MFR: 7.0 g/10 min) constituting the first polyolefin resin layer;
a mixture of polypropylene (manufactured by TPC Corporation, product name: FL7540L, density: 0.90 g/cm ³ , melting point: 138° C., MFR: 7.0 g/10 min) and a heat seal modifier (manufactured by Mitsui Chemicals, Inc., product name: Tafmer A-4085S, density: 0.885 g/cm ³ , melting point: 66° C., MFR: 3.6 g/10 min) (polypropylene:heat seal modifier=60:40 (by mass)), which constitutes the second polyolefin resin layer;
The resulting mixture was co-extruded by a T-die method to produce a heat seal layer having a structure of a first polyolefin resin layer (20 μm)/a second polyolefin resin layer (10 μm).

A 30 nm thick aluminum vapor deposition film was formed by PVD on the first polyolefin resin layer of the heat seal layer prepared as described above. The vapor deposition concentration (OD value) of the vapor deposition film thus formed was measured and found to be 3.0.

A biaxially stretched polypropylene film having a thickness of 25 μm (manufactured by Toyobo Co., Ltd., product name: P2108) was prepared as a substrate. An image was formed on one surface of the biaxially stretched polypropylene film by gravure printing using a solvent-based gravure ink (manufactured by DIC Graphics Co., Ltd., Finart).
The aluminum vapor deposition film-formed surface of the heat seal layer and the image-formed surface of the biaxially stretched polypropylene film were laminated via a two-component curing polyurethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-3600/H-689) to obtain a laminate for packaging materials. The proportion of the same polyolefin (PP) in the laminate thus obtained was 88% by mass.

Comparative Example 3
A laminate for packaging materials was obtained in the same manner as in Example 1, except that a biaxially oriented polyester film having a thickness of 12 μm (manufactured by Toyobo Co., Ltd., product name: E5100) was used as the substrate. The proportion of the same polyolefin (PP) in the laminate thus obtained was 53% by mass.

<<Recyclability evaluation>>
The recyclability of the laminates for packaging materials obtained in the above Examples and Comparative Examples was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
(Evaluation criteria)
Good: The content of the same polyolefin in the laminate for packaging material was 80% by mass or more.
×: The content of the same polyolefin in the laminate for packaging material was less than 80 mass %.

<<Strength evaluation>>
The laminates for packaging materials produced in the above Examples and Comparative Examples were measured for strength when pierced with a needle having a diameter of 0.5 mm using a tensile tester (manufactured by Orientec Co., Ltd., product name: RTC-1310A). The piercing speed was 50 mm/min. The measurement results are summarized in Table 1.

<<Heat resistance evaluation>>
Two test pieces each measuring 80 mm long x 80 mm wide were prepared from the laminates for packaging materials obtained in the above Examples and Comparative Examples.
The two test pieces were overlapped with the second polyolefin resin layers facing each other, and three sides were heat sealed at 140° C. to prepare a small pouch-shaped packaging material.
The prepared packaging material was visually observed, and the heat resistance of the laminate for packaging material was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
(Evaluation criteria)
◯: No wrinkles or the like were observed on the surface of the packaging material, and no adhesion to the heat seal bar was observed.
×: Wrinkles or the like were generated on the surface of the packaging material, and adhesion to the heat seal bar was observed, and bags could not be made.

<<Printability evaluation>>
In the above examples and comparative examples, the images formed on the substrate were visually observed, and the printability thereof was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
(Evaluation criteria)
A: The dimensional stability during printing was good, and a good image was formed without rubbing, bleeding, or the like.
x: The film expanded or contracted during printing, causing rubbing or bleeding in the formed image.

<Oxygen Barrier Property Evaluation>
The laminates for packaging materials obtained in the above Examples and Comparative Examples were cut to A4 size, and the oxygen transmission rate (cc/ ^m2 /day/atm) was measured at 23°C and a relative humidity of 90% using an OXTRAN2/20 manufactured by MOCON Corporation, USA. The measurement results are summarized in Table 1.

<<Water vapor barrier property evaluation>>
The laminates obtained in the above Examples and Comparative Examples were cut to A4 size, and the water vapor transmission rate (g/ ^m2 /day/atm) was measured at 40°C and a relative humidity of 90% using a PERMATRAN 3/31 manufactured by MOCON Corporation, USA. The measurement results are summarized in Table 1.

<Evaluation of bending load resistance>
The laminate for packaging material obtained above was subjected to a bending load (stroke: 155 mm, bending motion: 440°) five times in accordance with ASTM F 392 using a Gelbo Flex Tester (product name: BE1006BE, manufactured by Tester Sangyo Co., Ltd.).
After the bending load, the oxygen permeability and water vapor permeability of the laminate were measured. The measurement results are summarized in Table 1.

<<Heat sealability test>>
The laminates for packaging materials obtained in the above Examples and Comparative Examples were cut to a size of 10 cm x 10 cm to prepare sample pieces. The sample pieces were folded in half so that the second polyolefin resin layer was on the inside, and a 1 cm x 10 cm area was heat-sealed at a temperature of 140°C, a pressure of 1 kgf/ ^cm2 , and for 1 second.
The heat-sealed sample pieces were cut into strips with a width of 15 mm, and both ends that were not heat-sealed were held in a tensile tester to measure the peel strength (N/15 mm) at a speed of 300 mm/min and a load range of 50 N. The measurement results are summarized in Table 1.
The laminate for packaging material obtained in Comparative Example 1 was marked "-" since it was unable to measure the peel strength due to adhesion to the heat seal bar.

10: Laminate for packaging material, 11: Substrate, 12: Heat-sealable laminate, 13: Gas barrier resin layer, 14: Polyolefin resin layer, 15: Adhesive layer, 16: Vapor deposition film, 17: Adhesive resin layer, 18: First polyolefin resin layer, 19: Second polyolefin resin layer

Claims (5)

A laminate for packaging materials comprising a substrate, an adhesive layer, and a heat seal layer,
The heat seal layer is a resin film having a gas barrier resin layer and a polyolefin resin layer and formed by co-extrusion,
the substrate and the polyolefin resin layer are made of the same polyolefin,
the substrate is a stretched resin film made of the polyolefin,
The content of the polyolefin in the entire laminate for packaging materials is 80% by mass or more,
13. A laminate for packaging materials, comprising: a gas barrier resin layer having a thickness smaller than a thickness of the polyolefin resin layer. The laminate for packaging materials according to claim 1, comprising a vapor deposition film between the adhesive layer and the heat seal layer. the vapor-deposited film is an aluminum vapor-deposited film,
The laminate for packaging materials according to claim 2 , wherein the adhesive layer comprises a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound. The laminate for packaging materials according to any one of claims 1 to 3, wherein the heat seal layer has an adhesive resin layer between the gas barrier resin layer and the polyolefin resin layer. A packaging material comprising the laminate for packaging material according to any one of claims 1 to 4.